naturalness and the standard model | of particular significance

Of Particular SignificanceConversations About Science with Theoretical Physicist Matt Strassler

Naturalness and the Standard Model

sler [August 27 – September 9, 2013]

ct is closely related to the hierarchy problem.]

article physicists and string theorists mean when they refer to a particular array of particles

as “natural”? They don’t mean “part of nature”. Everything in the universe is part of nature,

natural” has multiple meanings. The one that scientists are using in this context isn’t “having

nature” but rather “typical” or “or “generic” — “just what you’d have expected”, or “the usual”

aturally the baby started screaming when she bumped her head”, or “naturally it costs more

r the city center”, or “I hadn’t worn those glasses in months, so naturally they were dusty.”

tural is when the baby doesn’t scream, when the city center is cheap, and when the glasses are

sually, when something unnatural happens, there’s a good reason.

ntexts in particle physics and related subjects, surprises — big surprises, anyway — are pretty

means that if you look at a physical system, it usually behaves more or less along lines that,

experience as a scientist, you’d naturally expect. If it doesn’t, then (experience shows) there’s

really good reason… and if that reason isn’t obvious, the unnatural behavior of the system

inting you to something profound that you don’t yet know.

rposes here, the reason the notion of naturalness is so important is that there are two big

n nature that we particle physicists and our friends have to confront. The first is that the

[often referred to as “dark `energy’ ” in public settings] is amazingly small,

to what you’d naturally expect. The second is that the hierarchy between the strength of

the strengths of the other forces is amazingly big, compared to what you’d expect.

one can be restated as follows: the Standard Model (combined with Einstein’s theory of

the set of equations we use to predict the behavior of all the known elementary particles and

— is a profoundly, enormously, spectacularly unnatural theory. There’s only one

hysics — perhaps only one aspect in all of science — that is more unnatural than the Standard

that’s the cosmological constant.

n of “Natural” and “Unnatural”

concept of naturalness is best illuminated by a bit of story-telling.

Naturalness and the Standard Model | Of Particular Significance http://profmattstrassler.com/articles-and-posts/particle-physics-ba...

1 of 62 10/21/15 10:23 AM

f friends of mine from college (I’ll call them Ann and Steve) got married, and now have two

ildren. Back when their kids were younger — say, 4 and 7 years old — they were pretty wild.

played rough, got mad at each other, threw things, and generally needed at lot of supervision.

nn bought some beautiful flowers and put them in her favorite glass vase. But before she put

the kitchen table, the doorbell rang. She ran to the front, carrying the vase, and as she made

the door, she absent-mindedly put the vase down on the small, rickety table that sits by the

ur later, Steve returned home with the kids, and sent them into the play room to occupy

s while he and Ann settled in from the day and prepared dinner. They heard the usual sounds:

crashes, the sounds of bouncing balls and falling blocks, yells of “no fair” and “ow! stop

oment of screaming that blissfully stopped almost as soon as it started…

y-five minutes later when Ann noticed the vase with the flowers wasn’t on the kitchen table.

ment searching the kitchen and dining room, she suddenly realized that she’d put it down and

t in the most dangerous place in the house.

t running into the play room, hoping she wasn’t too late. And what do you think she found

get three options (Figure 1). Choose the most plausible.

ase was exactly where she’d left it, comfortably placed at the center of the table.

ase was smashed, and the flowers crushed, down on the floor.

ase was hanging off the table, right at the edge, within a millimeter of disaster.

: After nearly an hour with the kids playing nearby, where is the vase? On the table?

ashed on the floor? Or right at the edge? We’d all believe the first two before we’d

believe the third — unless the third was carefully arranged.

nswer is #3. There it was, just hanging there.


2 of 62 10/21/15 10:23 AM

Fig. 2: Imagine a lot of different possible

universes, each one described by equations

similar to our own universe, but with small

adjustments.

I suspect you don’t believe me. Or at least, if you do believe me, you probably are assuming

be some complicated explanation that I’m about to give you as to how this happened. It can’t

that two young kids were playing wildly in the room and somehow managed to get the vase

tremely precarious position just by accident, can it? For the vase to end up just so — not

he table, not falling off the table, but just in between — that’s … that’s not natural!

t (mustn’t there?) be an explanation.

re was glue on the side of the table and the vase stuck to it before falling off? Maybe one of the

iding behind the table and holding the vase there as a practical joke on his mom? Maybe her

ad somehow tied a string around the vase and attached it to the table, or to the ceiling, so that

uldn’t fall off? Maybe the table and vase are both magnetized somehow…?

so unnatural as that can’t just end up that way on its own… especially not in a room with two

dren playing rough and throwing things around.

tural Nature of the Standard Model

let’s turn to the Standard Model, combined with Einstein’s theory of gravity.

to imagine a universe much like our

ibed by a complete set of equations —

in theoretical-physics speak — much

ndard Model (plus gravity). To keep

ple, let’s say this universe even has all

lementary particles and forces as our

nly difference is that the strengths of

and the strengths with which the

interacts with other known particles

determines how

s the known particles have) are a little

t, say by 1%, or 5%, or maybe even up

fact, let’s imagine ALL such

all universes described by Standard

equations in which the strengths with

he fields and particles interact with

are changed by up to 50%. What will

described by these slightly different

(shown in a nice big pile in Figure 2)

se imaginary worlds, we will find three general classes, with the following properties.

e class, the Higgs field’s average value will be zero; in other words, the Higgs field is OFF. In

worlds, the Higgs particle will have a mass as much as ten thousand trillion

00,000,000,000,000) times larger than it does in our world. All the other known elementary

cles will be massless (up to small caveats I’ll explain elsewhere). In particular, the electron will

assless, and there will be no atoms in these worlds.


3 of 62 10/21/15 10:23 AM

ig. 3: The universes in Figure 2, whose equations differ just slightly from those that

second class, the Higgs field is FULL ON. The Higgs field’s average value, and the Higgs

cle’s mass, and the mass of all known particles, will be as much as ten thousand trillion

00,000,000,000,000) times larger than they are in our universe. In such a world, there will

be nothing like the atoms or the large objects we’re used to. For instance, nothing large like a

or planet can form without collapsing and forming a black hole.

third class, the Higgs field is JUST BARELY ON. It’s average value is roughly as small as in

orld — maybe a few times larger or smaller, but comparable. The masses of the known

cles, while somewhat different from what they are in our world, at least won’t be wildly

rent. And none of the types of particles that have mass in our own world will be massless. In

of those worlds there can even be atoms and planets and other types of structure. In others,

may be exotic things we’re not used to. But at least a few basic features of such worlds will be

fraction of these worlds are in class 3? Among all the Standard Model-like theories that we’re

g, what fraction will resemble ours at least a little bit?

r? A ridiculously, absurdly tiny fraction of them (Figure 3). If you chose a universe at random

g our set of Standard Model-like worlds, the chance that it would look vaguely like our

ould be spectacularly smaller than the chance that you would put a vase down carelessly on a

nd up putting it right on the edge of disaster, just by accident.


4 of 62 10/21/15 10:23 AM

govern our own, may be divided into three classes. Of these, the first two are very

mmon — natural — but the third class is, relative to the other two, extremely sparsely

ulated. Surprisingly, our own universe — if the Standard Model actually describes all

of its particle physics — is found among this tiny set of unnatural universes.

(and it’s a big “if”) the Standard Model (plus gravity) describes everything that exists

ld, then among all possible worlds, we live in an extraordinarily unusual one — one that is as

as a vase nudged to within an atom’s breadth of falling off the table. Classes 1 and 2 of

are natural — generic — typical; most Standard Model-like theories would give universes in

e classes. Class 3, of which our universe is an example, includes the possible worlds that are

non-generic, non-typical, unnatural. That we should live in such an unusual universe —

since we live, quite naturally, on a rather ordinary planet orbiting a rather ordinary star in a

inary galaxy — is unexpected, shocking, bizarre. And it is deserving, just like the weirdly

e, of an explanation. One certainly has to suspect there might be a subtle mechanism,

about the universe that we don’t yet know, that permits our universe to naturally be one that

is the analogy to the playing children who endanger the vase, and make its balanced condition

implausible? It is quantum mechanics itself — the very basic operating principles of our world.

effects do not coexist well with accidental, unstable balance.

o discuss those quantum effects, and how they make the Standard Model unnatural, in a

But first, although I hope you liked my story, I should point out there’s one important

between the vase on the table and the universe. If somebody bumps the table or the vase, it

ly fall off, or perhaps, if we’re lucky, slide toward the center of the table. In other words, it can

e away from its precarious position if it is disturbed. Our universe, by contrast, is not in

of smoothly shifting its properties, and becoming a universe in Class 1 or Class 2.

s possible that someday it could shift suddenly to become a very different universe, through

nown as tunneling or vacuum decay, this event is likely to be unimaginably far off; this is a

another day, but it’s not something to worry about.] The real issue for the universe is in the

among the vast number of possible universes, did we end up in such an apparently unnatural

re something about our universe that we don’t yet know which makes it not as unnatural as it

perhaps the fact that many (most?) natural universes don’t seem hospitable for life has

to do with it? Or maybe we humans haven’t been clever enough yet, and there some other

ntific explanation? Whatever the reason, either it is due to a timeless fact or due to something

ned very long ago; the universe (or at least the large region we can see with our eyes and

) has been unchangingly unnatural [if the Standard Model fully describes it] for billions of

won’t be changing anytime in the near future.

e, let’s move on now, to understand the quantum physics that makes a universe described by

rd Model (and gravity) so incredibly unusual.

Physics and (un)Naturalness

please read about quantum fluctuations of quantum fields, and the energy carried in those

if you haven’t already done so. Along the way you’ll find out a little about another

s problem: the cosmological constant. After you’ve read that article, you can continue with


5 of 62 10/21/15 10:23 AM

he Higgs (and Other Similar Particles)

fluctuations of fields, and their contribution to the energy density of empty space (the

vacuum energy”) play a big part in our story. But our goal here requires we set the

cal constant problem aside, and focus on the Higgs particle and on why the Standard Model is

This is not because the cosmological constant problem isn’t important, and not because we’re

ain the two problems are completely unrelated. But since the cosmological constant has

to do with gravity, while the problem of the Higgs particle and the naturalness of the

odel doesn’t have anything to do with gravity directly, it’s quite possible they’re solved in

ays. And each of the two problems is enormous on its own; if in fact we need to solve them

usly, then the situation just gets worse. So let’s just send the cosmological constant to a far

ake a little nap. We do need to remember that it’s the elephant in the room that we can’t

t the Higgs field. There are three really important questions about the Higgs field and particle

nt to answer. [I’ll phrase all these questions assuming the Standard Model is right, or close to

f it isn’t, don’t worry: the ideas I’ll explore remain essentially the same, even though slightly

iggs field is “ON” — its average value, everywhere and at all times, at least since the very

Why is it on?

GeV. What sets its value?

iggs particle has a mass of about 125 GeV/c!. What sets this mass?

o explain to you how and why these questions are related to the issue of how the energy of

ce (part of which comes from quantum fluctuations of fields) depends on the Higgs field’s

s Field’s Value and the Energy of Empty Space

ld — not just the Higgs field — how is it determined what the average value of the field is in

se? Answer: a field’s average value must have the following property: if you change the value

it, larger or smaller, then the energy in empty space must increase. In short, the field must

e for which the energy of empty space is at a minimum — not necessarily the minimum, but

(If there is more than one minimum, than which one is selected may depend on the

the universe, or on other more subtle considerations I won’t go into now.)

f illustrative examples of how the energy of empty space in our universe, or in some imaginary

ight depend on the Higgs field, or on some other similar field, are shown in Figure 4. In each

cases I’ve drawn, there happen to be two minima where the Higgs field could sit — but that’s

e. In other cases there could be several minima, or just one. The fact that the Higgs field is

world implies there’s a minimum in the universe’s vacuum energy when the Higgs field has a

6 GeV. While it’s not obvious from what’s I’ve said so far, we are confident, from what we

t nature and about our equations, that there is no minimum when the Higgs field is zero, and

our universe’s Higgs field isn’t OFF. So in our universe, the dependence of the vacuum energy

gs field probably looks more like the left-hand figure than the right-hand one, but, as we’ll see,

look much like either of them. If the Standard Model describes physics at energies much

at distances much shorter than the ones we’re studying now at the Large Hadron Collider


6 of 62 10/21/15 10:23 AM

ig. 4: How the energy density of empty space might depend on a Higgs-like field’s

rage value, in two different possible universes. The Higgs field’s average value must

t a minimum — not necessarily the lowest minimum — of the energy of empty space.

ere is more than one minimum, the one the Higgs field `chooses’ may depend on the

tory of the universe. The Higgs field may be ON (left) or OFF (right); but it can only be

F if the energy has a minimum when the field’s value is zero (as in the right-hand plot).

he mass of the Higgs particle is determined by how sharply curved the minimum is

ere the field’s value lies — if the energy rises slowly away from the minimum (left) the

s particle will have a small mass, while if it rises more rapidly away from the minimum

(right) the Higgs particle will have a larger mass.

n the form of the corresponding curve is much more peculiar — as we’ll see later.

s Particle’s Mass and the Energy of Empty Space

t the Higgs particle’s mass? It is determined (Figure 4) by how quickly the energy of empty

ges as you vary the Higgs field’s value away from where it prefers to be. Why?

rticle is a little ripple in the Higgs field — i.e., as a Higgs particle passes by, the Higgs field has

a little bit, becoming in turn a bit larger and smaller. Well, since we know the Higgs field’s

lue sits at a minimum of the energy of empty space, any small change in that value slightly

hat overall energy a little bit. This extra bit of energy is [actually half of] what gives the Higgs

mass-energy (i.e., it’s E=mc! energy.) If the shape of the curve is very flat near the minimum

4), the energy required to make a Higgs particle is rather small, because the extra energy in

g Higgs field (i.e., in the Higgs particle) is small. But if the shape of the curve is very sharp

inimum, then the Higgs particle has a big mass.

he flatness or sharpness in the curve in the plot, at the point where the Higgs field’s value is

he “curvature at the minimum” — that determines the Higgs particle’s mass.

n’t Easy to Have The Higgs Particle’s Mass Be Small


7 of 62 10/21/15 10:23 AM

is measured to be about 125-126 GeV/c!, about 134 times the proton‘s mass.

an’t we just put that mass into our equations, and be done with this question about where it

m is that the Higgs field’s value, and the Higgs particle’s mass, aren’t things you put directly

quations that we use; instead, you extract them, by a complex calculation, from the equations

d here we run into some difficulty…

se two quantities — the average value and the mass of the field and particle — by looking at

ergy of empty space depends on the Higgs field. And that energy, as in any quantum field

the Standard Model, is a sum of many different things:

gy from the fluctuations of the Higgs field itself

gy from the fluctuations of the top quark field

gy from the fluctuations of the W field

gy from the fluctuations of the Z field

gy from the fluctuations of the bottom quark field

gy from the fluctuations of the tau lepton field

for all the fields of nature that interact directly with the Higgs field… I’ve indicated these —

ally! these are not the actual energies — as blue curves in Figure 5. Each plot indicates one

n to the energy of empty space, and how it varies as the Higgs field’s average value changes

to the maximum value that I dare consider, which I’ve called v .

e of you may have read that these calculations of the energy of empty space give infinite

is is true and yet irrelevant; it is a technicality, true only if you assume v is infinitely

hich it patently is not. I have found that many people, non-scientists and scientists alike,

anks to books by non-experts and by the previous generations of experts — even Feynman

hat these infinities are important and relevant to the discussion of naturalness. This is false.

n to this widespread misunderstanding, which involves mistaking mathematical

ies for physically important effects, at the end of this section.]

? It’s as far as one could can push up the Higgs field’s value and still believe our calculations

Standard Model. What I mean by v is that if the Higgs field’s value were larger than this

uld make the top quark’s mass larger than about v /c ) then the Standard Model would no

urately describe everything that happens in particle physics. In other words, v is the

between where the Standard Model is applicable and where it isn’t.

is… and that ignorance is going to play a role in the discussion. From

appears to be something like 500 GeV or larger. However, for all we

could be as much as 10,000,000,000,000,000 times larger than that. We can’t go beyond

because that’s the (maximum possible) scale at which gravity becomes important; if v

arge, top quarks would be so heavy they’d be tiny black holes! and we know that the Standard

’t describe that kind of phenomenon. A quantum mechanics version of gravity has to be

that point… if not before!

is somewhere between 500 GeV and 1,000,000,000,000,000,000

max

max

max

max2

max

max

max

max

max


8 of 62 10/21/15 10:23 AM

Fig. 5: Summing up the energy from the quantum fluctuations of known fields

schematically shown, upper row) up to the maximum energy scale v (down to the

inimum distance scale) where the Standard Model still applies, and adding to this

contributions from unknown effects from still higher energies and shorter distances

chematically shown, middle row), we must somehow find what experiment tells us is

: that the Higgs field’s average value is 246 GeV and the Higgs particle’s mass is 125

is much larger than 500 GeV, this requires a very precise cancellation

between the known and unknown sources of energy, one that is highly atypical of

quantum theories.

In Figure 5, I’ve assumed it’s quite a bit bigger than 500 GeV; we’ll look in Figure 6 at the case

f the contributions in the upper row of Figure 5 is something we can (in principle, and to a

t in practice) calculate, for any Higgs field value between zero and v , and for all quantum

s with energy less than about v . [I’m oversimplifying somewhat here; really this energy

not be quite the same as v , but let’s not get more complicated than necessary.] If v is

ach one of these contributions is really big — and more importantly, the variation as we

Higgs field’s value from zero to v is big too — something like v /(hc) … where h is

uantum constant and c is the universal speed limit, often called “the speed of light”.

not all. To this we have to add other contributions, shown in the second row of Figure 5, which

physical phenomena that we don’t yet know anything or much about, physics that does not

pear in the Standard Model at all. [Technically, we absorb these effects from unknown

to parameters that define the Standard Model’s equations, as inputs to those equations; but

max

max

max

max max

max max4 3


9 of 62 10/21/15 10:23 AM

puts, rather than something we calculate, precisely because they’re from unknown

In addition to effects from quantum fluctuations of known fields with even higher energies,

uantum mechanics of gravity,

y particles we’ve not yet discovered,

s that are only important at distances far shorter than we can currently measure,

r more exotic contributions from, say, strings or D-branes in string theory or some other

ich may depend, directly or indirectly, on the Higgs field’s value. I’ve drawn these unknown

ed; note that these curves are pure guesswork. We don’t know anything about these effects

exist (and the gravity effects definitely exist), and that some or all of them could

… as big as or bigger than the ones we know about in the upper row. In principle, all these

be zero — but that wouldn’t resolve the naturalness problem, as we’ll see, so

there’s no obvious reason to expect these unknown effects in red

y way connected with the known contributions in blue. After all, why should

ravity effects, or some new force that has nothing to do with the weak nuclear force, have

o do with the energy density of quantum fluctuations of the top quark field or of the W field?

like conceptually separate sources of the energy density of empty space.

the puzzle. When we add up all of these contributions to the energy of empty space [Unsure

d curves like these together? Click here for an explanation…] — each of which is big and many

ary a lot as the Higgs field’s value changes from zero to the maximum that we can consider —

incredibly flat curve, the one shown in green. It’s almost perfectly flat near the vertical

not quite at zero Higgs field; it’s slightly away from zero, at a Higgs field

All of those different contributions in blue and red, which curve up and down in

grees, have almost (but not quite) perfectly canceled each other when added together. It’s as

piled a few mountains from Montana into a deep valley in California and ended up with a

How did that happen?

bad is this problem? How surprising is this cancellation? The answer is that it depends on

is only 500 GeV, then there’s no real cancellation needed at all — see Figure 6. But if v is

ancellation is incredibly precise, as in Figure 5. The larger is v , the more remarkable it is

contributions cancelled.

rkable? The cancellation has to be perfect to something like one part in (v /500 GeV) , give

is close to 500 GeV, that’s no big deal; but if v = 5000 GeV, we need a

n to one part in 100. If it’s 500,000 GeV, we need cancellation to one part in a million.

as high as possible — if the Standard Model describes all non-gravitational particle

we need cancellation of all these different effects to one part in about

0,000,000,000,000,000,000,000,000.

case, the incredible delicacy of the cancellation is particularly disturbing. It means that if you

max

max

max2

max


10 of 62 10/21/15 10:23 AM

is not much much larger than 246 GeV, then no special cancellation is really

uired; the sum of the blue and red curves could easily look something like the green

is much larger do we get the surprising effect seen in Figure 5, where,

mpared to the scale at which the blue and red curves wiggle, the green curve is very

flat.

the W particle’s mass, or the strength of the electromagnetic force, by a tiny amount — say,

a million million — the cancellation would completely fail, and you’d find the theory would

1 or Class 2, with a ultra-heavy Higgs particle and either a large or absent Higgs field value

3). This incredible sensitivity means that the properties of our world have to be, very

— like a radio that is set exactly to the frequency of a desired radio station, finely

ch extreme “fine-tuning” of the properties of a physical system has no precedent in science.

another way: what’s unnatural about the Standard Model — specifically, about the Standard

g valid up to the scale v , if v is much larger than 500 GeV or so — is the cancellation

igure 5. It’s not generic or typical… and the larger is v , the more unnatural it is. If you take

generic curves like those in Figure 5, each of which has minima and maxima at Higgs field

t are either at zero or somewhere around v , and you add those curves together, you will find

m of those curves is a curve that also has its minima and maxima at

[Class 2 theories — see Figure 3],

theories],

ot somewhere non-zero that is much much smaller than v [Class 3 theories].

if the curves are substantially curved near their minima and maxima, their sum will also

ave substantial curvature near their minima and maxima [i.e. the Higgs particle’s mass will be

, as in Class 1 and Class 2 theories], and won’t be extremely flat near any of its minimum

r the Higgs particle to be much lighter than v /c , as occurs in Class 3 theories.] This is

for the addition of just two curves, in Figure 7, where we see the two curves have to have a

l relationship if their sum is to end up very flat.

naturalness problem. It’s not just that the green curve in Figure 5 is remarkably flat, with a

at a small Higgs field value. It’s that this curve is an output, a sum of many large and

max max

max

max

max

max

max2


11 of 62 10/21/15 10:23 AM

Fig. 7: (Top) If you add together two generic curves, the result will be a

curve that is also generic. (Bottom) Only if the two curves have equal

and opposite curvature in the region near the blue arrows will the

result of adding them together be nearly flat. While this could happen

by pure accident, it is perhaps more likely that there was a hidden

relation between the two curves which assured they were nearly equal

and opposite.

ities seem to be somehow swept under the rug, leading to finite predictions. These infinities,

emoval via renormalization, sometimes lead people — even scientists — to claim that particle

don’t know what they are doing, and that this causes them to see a naturalness problem where

s are badly misguided. These technical issues (which are well understood nowadays, in any

ompletely irrelevant in the present context.

ies that arise in certain calculations of the Higgs particle’s mass, and of the Higgs field’s value,

of the naturalness problem, a mathematical symptom that shows up if you insist on

to infinity, which, though often convenient, is an unphysical thing to do. The infinities are

aturalness problem, nor are they at its heart, nor are they its cause.

any ways to see this, one very easy way is to study the wide variety of finite quantum field

discovered in the 1980s (a list of references can be found in an old paper of mine with Rob

w a professor at the University of Illinois].) These theories have minimal amounts of

, as well as being finite. If you take such a theory (see Figure 8), and you ruin the

, while assuring the theory that remains at lower energies still has

fields like the Higgs field, you do not introduce any infinities. Moreover, there is no need

ially cut the theory off at energies below v (as I have done in Figure 5, separating known

nown) since in this example we know the equations to use at energies above as well as

. The energy of empty space, and its dependence on the various fields, can be calculated

max


12 of 62 10/21/15 10:23 AM

8: Infinities have nothing to do with naturalness.

amples of finite theories abound; if they have

symmetry, there is no naturalness problem, but if

ymmetry is only applicable above an energy scale

, then the naturalness problem immediately

pears, and no spin-zero Higgs-like particles are

ically found with mass-energy (i.e. E=mc energy)

far below E .

without any ambiguity, infinities, or

infinite renormalization. So — is

there a naturalness problem here

too? Do the spin-zero particles

generically get masses as big as

v /c ? Do the spin-zero fields have

values that are either zero or roughly

as big as v ? You Bet! No

infinities, no sweeping anything

under a rug, no artificial-looking

cutoffs — and a naturalness problem

that’s just as bad as ever.

By the way, there’s an interesting

loophole to this argument, using a

lesson learned from string theory

about quantum field theory. But

though it gives examples of theories

that evade the naturalness problem,

neither I nor anyone else was able (so

far) to use it to really solve the

naturalness problem of the

Standard Model in a concrete way.

Perhaps the best attempt was this

lso repeat this type of calculation within string theory (a technical exercise, which does not

assume string theory really describes nature). String theory calculations have no infinities.

, the energy scale where the Standard Model fails to work, is much larger than 500 GeV, the

s problem is just as bad as before.

etting rid of the infinities that arise in certain Higgs-related calculations does NOT by itself

fect the naturalness problem.

to the Naturalness Problem

logical grounds, a couple of qualitatively different types of solutions to this problem come to

123 Google

2

max

max2

max


13 of 62 10/21/15 10:23 AM

NATURALNESS AND THE STANDARD MODEL”

First Stab at Explaining “Naturalness” | Of Particular Significance

August 27, 2013 at 9:23 AM | Reply

le Matt. More please…

ugust 27, 2013 at 9:34 AM | Reply

xplanation. Is there a calculation as to exactly how unnatural our universe is or do

know that it is a small probability and the exact number is dependent on the

f various theoretical frameworks one may use? I want to know whether the

is something on the order of one in one to the googol or something even much


do a precise (or rough) calculation if you make definite (or rough) assumptions.

l problem is that you don’t know the probability “measure”. One way to say this is

roll two dice and I *assume* they are fair dice, then I can calculate the probability

ice showing 9 dots. But if I don’t *know* they are fair dice, I can’t calculate it. If I

ey are roughly fair, I can roughly calculate.

n the situation of having at best an extremely rough guess at the probabilities, so

, at best, an extremely rough estimate. But when you’re dealing with numbers that

small, getting them wrong by a huge amount doesn’t change the qualitative

ion: our universe, no matter how you calculate it, is very unusual, on the face of it.

August 28, 2013 at 10:22 PM | Reply

ught the idea of random physical constants was still speculative. The basic theory,

nderstand it, is that we began as a fluctuation within a multiverse from which

y other universes may also have been born; is that right? But what if our universe

s out to be — as most physicists seemed to believe when I was at Berkeley — the

one? In that case, maybe you will have to wait for more experimental data, or

e mathematical revolution, before you can say anything definite about the values of


: sorry meant to write is the probability one in a googol, not one in one to the


ve values for the fractions?


14 of 62 10/21/15 10:23 AM

a hard time estimating the number of balls in the other two figures


remark by the mathematician below, and my (upcoming) reply. We cannot

te the fraction without defining a probability measure. Nevertheless, when you are

with numbers this gigantic, you can see you have a serious problem even if you

ow if the problem is one in a million trillion or one in a trillion trillion or one in a

trillion trillion. The point is that it’s certainly not one in a thousand.

st 27, 2013 at 10:47 AM | Reply

e that this is heading in the same direction as the anthropic principle. Do you

wo ideas, ie anthropic P and Naturalness, are the same, linked, or totally different.


important, before you start talking about solutions to a problem, to make sure

erstand the problem. I cannot answer your question without having gone further

rticle; please be patient.


matician (not a physicist) I find this argument rather unconvincing. It depends

tally on the existence of some meaningful measure on the parameter space which is

removed from the scale in which we choose to express the model. After all, if you

nough times, any numbers become the same order of magnitude. Are we certain

ole problem isn’t just caused by a misrepresentation of the parameters? It’s not as

xamine the parameter space experimentally.

there is something important to explain, but the same is true for all the other

s of the model: why do they take precisely the values we measure in experiments?

e is a deeper theory which explains them all (presumably including the very large

e are part of a multiverse, and anthropics explains away anything.

ole problem be reduced to “big numbers are more important than small ones”?


ument is NOT entirely convincing. But it is a strong argument nevertheless,

the numbers involved are so huge — typically something like 10^{-32} or so —

’d have to have a hugely convoluted measure on the parameter space to make it

short: if it is a problem of “a misrepresentation of the parameters”, then it’s a huge

whose solution will likely earn someone a professorship at a major university,

bably a Nobel Prize if it can be shown to be true experimentally. Certainly no one

r proposed a re-representation of the parameters which, without adding new

s accessible at scales fairly close to the Higgs particle’s mass, would bring us even

solving the problem. It’s easy to say it’s just a problem of the measure — but give

example where this would solve a naturalness problem in quantum field

and I’ll be extremely impressed.


15 of 62 10/21/15 10:23 AM

akes the argument much more convincing is that there are solids and fluids to

imilar arguments apply. The equations are of the same type (Quantum Field

) and there are higgs-like scalars (which are massless at phase transitions.) If you

andom solid or fluid system away from a phase transition, and ask if it has scalar

s that are vastly lighter than other massive degrees of freedom in the system, the

is “no”, unless they are Nambu-Goldstone bosons (which the Higgs in the

rd Model is not). The same is true for the few examples in particle physics. The

rd Model (if indeed it is the complete theory of nature) is unique in this regard. I’ll

this more later in the article, I think.

se a selection bias (i.e. anthropic principle or something similar) is one possible

tion… but an incomplete one within the Standard Model, because appealing to a

n bias ***also*** requires you to know a probability measure within the

rse… perhaps the dynamics which causes one set of parameters to be realized more

an another… so it doesn’t resolve the problem you mentioned for the naturalness

our last question (if I understand it correctly) — this kind of thing is under active

ion, of course. The answer may be yes. How will we verify this, however? That is

stion that has to be addressed… otherwise, it will remain speculation.


nks! To expand on my last question, my training is in logic, and to me, any number

ept perhaps 0, 1, e & pi) begs for an explanation. I’m uncomfortable with the idea

small numbers might just be facts of life, but large numbers can’t be. Information

ent is not dependent on magnitude.


ut logic and math is different from physics. For example, you may be 1.24534

imes taller than your wife. Does that require explanation? No. Why not? Because

his ratio is determined by a combination of a dynamical equation, on the one

initial conditions which are not given by pure numbers, on the other.

n general, in physics, dynamical equations (i.e. equations that describe how things

hange) assure that most pure numbers that we measure are of the order that we

ould (with experience) guess, up to factors between, say, 0.1 and 10. Sometimes

ou’ll see something as small as 0.01 and 100, just by accident, or even a bit greater.

o I would claim you’re profoundly misled by thinking about physics as similar to

gic or number theory. It’s not… it’s dynamical evolution, and most results of

hysics problems are not nice numbers like 1 or pi or even e^pi.

he notion that extremely large (and extremely small) numbers require explanation

as a history going back nearly a century and has been extremely profitable for

cientists. No explanation is needed for numbers like 3.2435 or 0.543662 — it’s not

matter of “information content”, it’s a matter of whether the dynamical equations

e know are likely or not to spit out such a number.


16 of 62 10/21/15 10:23 AM

August 28, 2013 at 6:41 AM |

OK, but doesn’t that mean you’re assuming that there is some kind of dynamics

in the parameter space? That it is governed by laws of the same character as the

laws of physics, even though we can never test those laws in any way?

August 28, 2013 at 9:07 AM |

Going back to your vase/table analogy, aren’t you also assuming that we are at a

stable point in the dynamics of parameter space? I.e. that the vase isn’t still

falling (with respect to parameter space dynamics)?

This would make sense if you assume that the dynamic parameter is our own

familiar time, and all this happened before we could measure any of the

parameters of the model, but given the local nature of time in GR, this seems

quite a strong assumption.

August 28, 2013 at 10:39 PM |

That point — about dynamical equations — helps me understand better what you


hen the number represents the odds against an event that has demonstrably

ccurred, then of course bigger numbers demand more of an explanation than small

nes. If you disagree, I’d be interested in hearing your reasoning why over a game of

100 minimum-bet craps. I’ll bring the dice. ;)

August 30, 2013 at 8:42 AM |

This is precisely my point: when you play dice, you know that, however biased

the dice may be, there is still some probability measure governing their fall. Even

if you don’t know what the odds are, you still know that the dice behave

randomly, so you can use both your experience of games and statistical theory to

reason about what’s happening, and to judge when the game is fixed.

When you consider the basic parameters of your model of physics, you don’t

have that. If Einstein was right, and time is part of the universe, then the

question “When were the parameters determined?” doesn’t make sense, because

there wasn’t any such “when”. Even the question “How were the parameters

determined?” assumes that there is some mechanism that operates beyond our

physics to determine them. Saying that large numbers require more explanation

than small ones is making assumptions about this mechanism.

I simply want to know what the assumptions behind the naturality argument are.

I don’t think it follows from just assuming that GR + SM is all there is.

Torbjörn Larsson, OM | September 1, 2013 at 5:11 PM |


17 of 62 10/21/15 10:23 AM

If physics is dynamic, the parameters can be determined anytime. As I

understand it, in some models the particles “freeze out” as the temperature of

the universe dropped. And that could happen differently in different places. (So

called landscapes of, say, string theory with many possibilities for physics.)

September 3, 2013 at 7:03 PM |

It’s actually about whether or not you need any such parameter-forcing

mechanism exists at all. GR+SM allow the parameters to be anything, with no

preferences. The values are arbitrary.

If the numbers were small, as in the ratio of the size of the total parameter space

to the subset that created a recognizable (i.e. has atoms in it) universe was

reasonable, then you could continue to say that the values are arbitrary, i.e. no

mechanism behind them needed, the Null Hypothesis, Occam’s Razor, and

getting a universe like ours is still no surprise.

When the numbers are this ridiculously huge, then you do need some

mechanism to explain how the parameters ended up this way. You either have to

figure out some “mechanism that operates beyond our physics” to force these

parameters to end up in this particular state, or you have to rely on the

Anthropic Principle to beat the long odds.

So the assumption is to *not* assume a bias in the parameter space, *not* to

assume some meta-physics mechanism for forcing parameters or merely biasing

them. That’s why it follows from assuming GR+SM is all there is. But then we

run into the problem which suggests that can’t be true.


I realized might be saying “Well you’re assuming a uniform distribution, and

why’s that assumption any better than any else”, so I wanted to make the point

more clear: The less fine-tuned the parameters need to be, the less need there is

to make any assumption at all. As in: Pick whatever distribution or rule for the

parameters you want. Does it result in a universe vaguely like ours? With the big

numbers we have, you need a very finely specified rule to get the parameters we

have and figuring out which one would be a big problem. With small numbers,

just about any rule would work, so you ultimately don’t need to assume any rule

Torbjörn Larsson, OM | September 1, 2013 at 5:06 PM | Reply

appealing to a selection bias ***also*** requires you to know a probability

measure within the multiverse…

n’t understand this point. Is the claim that despite Weinberg was able to predict

alue of today’s vacuum energy (cosmological constant) it isn’t relevant to selection

? And why would a full measure (as I assume the text is describing) be necessary?


18 of 62 10/21/15 10:23 AM

rect comparison would be biology and its selection bias. The full fitness space is

r known, nor its underlying mapping to physics. To look for ecological niches in

oastal zone you don’t need to know the exact waves, the exact dynamics of waves,

e exact probability distribution function of waves. You need to know the extremes

the optimum of the “niche construction”, what the population deems fit and

uld have assumed a gaussian centered on the average between the habitable limits

nnatural parameters (cc, Higgs mass-squared parameter), a gaussian because of

ribution of many other factors in the SM, would be the expected and needed

ability measure for selection bias. Why wouldn’t that work?

claimer: astrobiological interest, hence cosmological interest.]

rbjörn Larsson, OM | September 1, 2013 at 4:46 PM | Reply

think we can claim that we can’t examine the parameter space of universes

entally. People have suggested that in some cases of multiverses we could observe

collision “trace fossils”. So there are experimental constraints on this parameter

hether the answer would be positive or negative.

| Reply

derstanding that one of the assumptions that goes into predicting classes 1 &2

h more probable than class 3, is that there is no new physics between the Higgs

lanck scale. If this is correct it seems like a non-conservatively radical assumption.


se it is. I made very clear what my assumption was: that there is the Standard

lus gravity, and nothing else. The whole point is that the unnaturalness of the

gives us reasons to think the assumption is wrong. But we have a long way to go

e understand the crucial subtleties.


, unless someone finds reason for unnaturalness (extremely small probability

are stuck with anthropic argument. I am not an atheist. So I do not mind!!! But

le are shocked by this and try to get out of this by multiverse argument. Question:

r opinion on idea of multiverse which has practically zero chance of verification?


-anthropic-principle arguments (which are statistical and do not

any discussion about where the universe [or if you prefer, “multiverse”] came

ith arguments abut the existence of a non-scientific (for example, divine) origin of

verse. There’s no conflict between atheism and the weak anthropic principle. Only

form of the anthropic principle — “the universe was designed

ally for humans” — requires any discussion of who did the designing. This is not

of the anthropic principle discussed today by scientists.


19 of 62 10/21/15 10:23 AM

ur being “stuck with an anthropic argument”, you’re jumping the gun a bit.

ber the LHC hasn’t run at its highest energies yet and has collected only 10% of its

ta set (in fact it’s now 1% of the total through the planned upgrade into the year

so.) We do not know that the Standard Model is correct; I’m merely pointing out

rprising it will be (from the naturalness point of view) if it is.

| August 27, 2013 at 12:33 PM | Reply

y. I did not want to bring in religion in this discussion. But my understanding is

multiverse idea was brought in to get out of fine tuning (perhaps without any

ive to fight anthropic, weak or strong argument). String theory also points to that.

until it is verified experimentally, it remains one of the hypotheses, which is ok

me. I would still like to hear your opinion about multiverse.



to see the conclusions in your final text version. I think that there is no

s after all (based on my hypothesis). I’ll get back to you on this issue later.


is no naturalness, there is no time dilation, there is no constancy of speed of light,

ence to it, we will be never aging.

is no unnaturalness, there is no “rest (invariant) mass” and there will be no matter


is that? Could you open up your reasoning a bit?


ime slowdown means, nearing the speed of light and ultimately the clock stop

icking – thus becoming massless.

asslessness of standard model is naturalness.

he unnatural disturbance in simple harmonic motion of quantum fields (natural)

reates the “rest mass”, due to quantum mechanics.

he mass of know particles in standard model is unnaturalness ?


ysical reality, it is naturalness or unnaturalness ?


20 of 62 10/21/15 10:23 AM

ugust 27, 2013 at 1:41 PM | Reply

ly 100% sure, that the universe will not be changing any time soon? Elsewhere I’ve

t vacuum transitions etc …?


ertainly not change smoothly, which was really the only point I was making here.

s unlikely to change soon.

t this with the vase. A breath of fresh air or a little vibration could destablize it at

Reply

ntry, but “…we live, quite naturally, on a rather ordinary planet…” is jumping the

n’t know the probability measure any more than we do for the multiverse. And I

e Moon makes the Earth distinctly unnatural, even if Earth-mass planets are

found in stellar habitable zones.


lanet mass and its habitability is frequent (at ~ 6 % of stars). But systems are

uals, and our sun is unusually large (at ~ 5 % of stars).

ese types of large binaries are expected because they are, well, natural outcomes

ional accretion. We have many examples already in our system, Earth-Moon,

haron and smaller binary asteroids. And they are a natural outcome of low

, equal mass accretion models, which predicts Pluto-Charon and is now a strong

er for Earth-Moon. (Meaning the ancestral Tellus and Theia planetoids were likely

massed objects, an apriori most likely situation.)

moons have little to say on short-term habitability of planets. The -90’s results

med to say they are, are now known to be faulty. Both abiogenesis and later

n of complex life are possible outcomes.


don’t know the probability measure”, see the Habitable Exoplanet Catalog: we do,

ell, from 3 independent sources (transits, radial veolocity and microlensing).

ptember 5, 2013 at 11:12 AM | Reply

rding to your source: zero confirmed “habitable” Earth-mass planets out of ~1000

irmed planets in the The Extrasolar Planets Encyclopaedia. Too soon to say “rather

nary planet” in my book. And, based on the evidence to date, our solar system

etty atypical, too. (Eight planets!)

:)


21 of 62 10/21/15 10:23 AM

ging habitability into it was a mistake, because I was only making a pedantic point

t the “naturalness” of the Earth. I’m not sure Jo[e] Public would consider a planet

an orbital period of 28 days or twice the radius of the Earth as “Earth-like”, even if

apable of supporting life! (As aside, the Habitable Exoplanet Catalog doesn’t seen

count for tidal locking, and I would bet against life on those that are tidally

nk it would be even more incredible than predicting the Higgs for our model of

etary formation to survive the exoplanet revolution.

alue references on the third point about moons and habitability. Of course, now we

w” life had to evolve on Mars and then jump ship to Earth before Mars became

habitable… so now you need two planets! (No, I don’t believe that, but it would

ainly answer the Fermi paradox!)

Torbjörn Larsson, OM | September 9, 2013 at 5:42 AM | Reply

ow you have gone beyond habitability into inhabitation.

Add Earth to HEC and you have that 10 % of habitables are inhabited. This

stimate will slowly decrease until we find another inhabited planet, but it won’t

It is really finetuning if you expect just one planet out of a galaxy worth to be

habited. About 10^-13 (since we have many planets and ice moons per star),

hich is nearly as serious as what we discuss here.

The short period of time before life evolved on Earth shows that it is an easy

rocess, so a frequent outcome.

o get back to habitability:

As I said, the systems are individuals, planets not so much re traits like being

laced in the habitable zone.

“Tidal lock” is a tedious claim of “show stopper”, while we already know it isn’t.

limate models, as well as the example of nearly locked Venus, shows that dense

tmospheres will nicely distribute heat without too much surface wind. So the

requency of habitables isn’t as large as it could be, but still large. (Especially since

ost habitables will be locked around M stars.)

Large moons not necessary ref: http://phys.org/news/2011-11-life-alien-planets-

It seems that the 1993 study did not take into account how fast the changes in tilt

ould occur; … According to Darren Williams of Pennsylvania State University,

Large moons are not required for a stable tilt and climate. In some circumstances,

rge moons can even be detrimental, depending on the arrangement of planets in a


22 of 62 10/21/15 10:23 AM

iven system. Every system is going to be different.””

o, the argument isn’t that you need transpermia. (But we know it could happen

rom estimates of hypervelocity impact escape masses and bacterial survival rate.

e also know that many systems will have 2-3 planets within the habitable zone as

he argument is that you can evolve life robustly as it takes much less than 0.5

illion years, then evolve land life and intelligence in a similar calm period. Again,

wered outcome, no show stopper.

lso, I think the discovery of Earth global oxygenation and global “slush ball” glacial

how that orbital stability is overrated. Life survives much worse changes.

Torbjörn Larsson, OM | September 9, 2013 at 5:53 AM |

I’ll add on your last point that the Fermi question is insufficiently constrained to

be tested by negative outcomes. (A positive outcome would do.)

There will always be the problem of silent pathways, false negatives. E.g. if there

is no generic interest to communicate. It is anthropocentric to assume there is.

So it isn’t a fully testable question, a well defined hypothesis, with a definite

answer. We can only constrain (or hopefully verify) frequency of positives.


it. Why limit ourselves to variations of the Standard Model? Why not imagine all

odels? Our imagination is limitless, after all. Of course, then all the variations of

odel will feel utterly unnatural compared compared to the enormous pile of

en if we assume the Standard Model is the correct description of the universe, than

odel, even those that are quite similar, are still as fictional as the Genesis.


ber, the article isn’t finished yet.

try to imagine all possible worlds that are described by quantum field theory. [I

idea how other worlds would work, so there’s no point in discussing them; the

rd Model is a set of equations for which quantum field theory works.] Then my

nt would have to be generalized to the following: divide the set of quantum field

) those that have spin-zero particles like the Higgs particle, but no supersymmetry

e other technical caveat that I’ll explain later in the article), that are “lonely” (i.e.

t other particles around that specifically have to do with why they are light)


23 of 62 10/21/15 10:23 AM

nd the vastly overwhelming majority of the theories are in Class B. But the

rd Model is in Class A. So the mystery, now stated more thoroughly but more

ngly (which is why I chose, for pedagogical reason, not to jump that far in one

emains just as serious as before.


nd trivial, but what if the universe is actually passing through cycyles 3-2-1 etc due

ge of higgs field value over time? If so, it would be perfectly “natural” to pass

seemingly “unnatural” transitory phase such as the one we are in, sometime during


know much physics yet, but I feel like there’s something in this proposal that

at the fundamental truth of the Universe hidden till now to the scientists.


impossible, logically speaking. Our scientific problem is this: how would we verify,

entally, that this is the case?


’t we at least put forward some imposibility of implausibility arguments against my

estion? If, as I suggest, the universe has been cycling between these three

ses”, could one say that, than, we should by now have observed some tell-tale signs

ast of the “debris” of the previous phase, which, presumably we have not? Or

aps one could “prove” by logical reasoning based on proven observations and

ysis, that, once a universal phase change occurs due to change over time of the

s field, the new “state-space” of universe would now provide such a strong

actor” for the new status quo that, no further phase changes (new criticality events

rds other attractors) would be possible theoretically, thus “extinguishing” the

y above reasoning, this suggestion is proved to be false that that is the end of the

y. However, if this is indeed possible, than why would one bother with naturalness

nnaturalness arguments, perhaps inevitably(?) leading to multi-universe theories,

h philosophically put the burden of “explanation” to the 3 Space(distance)

ensions, whereas, this apparent “unnaturalness” may be explianed by just

rence to 1 D time dimesion? I do realize that I may be edging unduly towards self

nized criticality theories (which I don’t belive is a holy grail of explanatory power

verthing anyway), but still, I believe this line of reasoning deserves some further



24 of 62 10/21/15 10:23 AM

m repeating Donald’s question.But I did not understand your answer to his

n SM range of values of constants is probably known (am I right?) So what is it

es it unfair dice rolling? I suppose, once you get into small numbers exact value

atter!! But if you have large no of systems (multiuniverses or whatever) the net

may become reasonable. I have seen Penrose’s estimate of big bang starting with

y as 1 in 10^10^123. Other people who consider probability of origin of life as 1 in

in 10^150. Leaving aside question of life, is there any believable range of

for SM parameters (even rough!) ? Thanks.


lk a little bit about how we can put some precise numbers into the discussion; but

nd, there is no unique way to do this. And that could, perhaps, be the Achilles’ heel

rgument. [However, I remind you that the argument has always worked before in


lihood for chemical evolution proceeding to biological evolution is of order 1*,

ow fast life was established here and consonant with the known homologies

n ocean water and cells (frequency of commonest elements, i.e. CHNOPS) and

n pH modulated alkaline hydrothermal vents and early chemoautotroph

lism (Lane & Martin 2012). If abiogenesis was hard either of those would not be

stead it was fast and used the common elements and redox sources at hand on

an make that formal and testable with stochastic processes. Or at least as testable

astic processes are verifiable in industry from single samples…

ust 27, 2013 at 9:52 PM | Reply

ne hand the standard model ist a profoundly unnatural theory, on the other hand

t our scientists got? That reminds me a bit of the ptolemaic world view, where the

d the sun had to carry out weird movements in order for the earth to be in the

the phlogiston theory, where “phlogiston” with negative mass was postulated, in

plain the weight loss when burning substances. Both “correct” and useful within

s, transitional theories, but something profound was missing and it was back then

not be surprised if someday in a far future the standard model will be replaced by

quite, but not completely different. Like a reformulation from an different

But I dont believe I will witness that, it seems too far out.

ent note, to state the limitations of the current scientific world view so clearly

dibility to me. Best defense against all kind of conspiracy theories wich typically are

gnorance of “mainstream” science.


25 of 62 10/21/15 10:23 AM


zing how, on the interweb, you find people who’ve had exactly the same thought!

ked at the SM for years and thought “epicycles” and “phlogiston,” that there has to

e key piece of understanding that’s just not right. The fundamental conflict

n GR and SM feed into that feeling; one of them has to be, at the least, incomplete,

Emotionally, I want Einstein to have been exactly right and SM in need of an

derstand the naturalness conundrum, either there must be a lot of universes

ng we’re not special; just another member of the pack) or we need a reasonable

tion for why the dice came up with a very rare number that allows us to be here to

zed that we’re here. If we’re not special, no problem, but if we are special… then…

n reading about the Rare Earth Hypothesis and the idea that multicellular life may

en incredibly unlikely, let alone intelligent life. Some feel the famous Drake

n factors should be such that the probability of intelligent life per galaxy is

may be hugely special, and that does seem to beg for an

others me is that The Blind Watchmaker logic seems sound. The eye was a poor

e, as there is a clear evolutionary explanation. But more and more it seems that life

erhaps even physics itself, is a kind of weirdly complex, inexplicable watch. It’s

t to think it was made or directed in some fashion (as preposterous as that

olin’s idea about the evolution of universes is interesting, but if universes evolve to

e physics laws they do, what is the physics context in which this evolution takes

s there a meta-physics universe where universes evolve? (Isn’t that the Turtles

?) I wonder the same thing about the BB. Under what laws of physics was the BB

ime reader, first time commenter, retired software designer with a lifelong interest


d the REH daft, since it is an open-ended bayesian model. Just find the posterior

want between 0 and 1 by adding factors.

the REH original factors have all already been shown to be erroneous. (For

ple, the need for a large moon, se my previous comments on that.)


e dilation doesn’t mean that particles come massless. There is two factors in time


26 of 62 10/21/15 10:23 AM

e strength of gravitational interaction and the velocity in it. If we take a

3 atom near a huge gravitational source where it “ticks” much slower than here

s the mechanism that makes its mass smaller?

near c velocities, again what mechanism would make it have smaller mass? Ticks

for sure, but it has nothing to do with subatomic masses (nuclei, nucleus,

gust 28, 2013 at 1:38 AM | Reply

is the cosmological constant “unnatural”? After all, its value is quite exactly the

are of the horizon distance (“radius of the universe”). This is a quite natural value


ut you missed one state of vase in your analysis: the vase is in its fall down. Maybe

se “is falling down” between two “natural” states and maybe the notion of time

any meaning only for this “period” (and this is why we believe that the falling state

lling vase is rare when you compare it with the other two cases of natural states

le or on the floor) but it is a natural state too.

naturalness problem of our Universe is a false problem only because we just don’t

d yet what it is really happening.

ust 28, 2013 at 7:24 AM | Reply

t the most fundamental criteria for any universe is ,, meaning ,,……so no universe

ithout a sapien creature to grasp it and give meaning to it , no mathematical or

of can prove that statement as false.

as true is direct logical result from existence of homo sapien himself.

ust 28, 2013 at 7:29 AM | Reply

er view why it is not the case that our universe is the natural , normal ,expected

ll other ones are the weird non existent cases?

ust 28, 2013 at 11:37 AM | Reply

nore the obvious , the universe is un-natural since it was generated by conscious


at would you say in the case where universe (forces, particles) emerge, without any

ust 28, 2013 at 11:48 AM | Reply

ow me one single case or equation where physical output is generated without Any


27 of 62 10/21/15 10:23 AM

ny input of fields , particles or forces …….


ant an example then do some googling or follow the link. Of course there is

ing behind the big bang but after that everything emerge without any outside

ust 28, 2013 at 12:10 PM | Reply

eist response…….I SAY : NO input whatsoever ….no physical before the physical ,

ONLY way to prove ex-nihilio physical generation.

ost or paper ever started from real fundamental absolute NOTHING to generate

enomena , it is logical absurdity to state it , ….

rong , give me just one equation without any physical factors generating physical

O IT if you are so sure .


read my previous response? Apparently not. Or at least missed my point.

ust 28, 2013 at 12:25 PM | Reply

logical ,simple , scientific explanation is to admit Divinity of creation then study it

you can , I think we must admit that any pure scientific justification for actual ,

nothingness to generate any thing is just squaring the circle…….. Grave , false

ust 28, 2013 at 12:32 PM | Reply

.. All scientific papers started from something…….no single paper would start from

it will end after The first line.

ust 28, 2013 at 12:42 PM | Reply

ou , it have been a long time since our last conversation…..

example proves Divinity case as only omnipotent effector can adjust line of center

ith line of support and KEEP it that way…………thanks Matt. You proved that our

eds extra-cosmic effector by just comparing it to the vase case……….Great

ust 28, 2013 at 12:45 PM | Reply

u agree Kimmo, that generating our cosmos needs something behind it ?


agree. But it doesn’t have to be any “higher power” type of thing.


28 of 62 10/21/15 10:23 AM

ust 29, 2013 at 6:27 AM | Reply

? There are none that you can find …….it is an infinite regression with no real

st 30, 2013 at 4:11 AM | Reply

nd that many theorists are upset (not merely puzzled, but upset) at the elusiveness

/principles like “naturalness” in evidence from experiments. What puzzles me is

upsetting, when we _know_ that the SM and GR are both incompatible and

e, with something like 95% of the contents of the universe not even hinted at by

ry. (In fact, we have no idea how a Lambda-CDM universe could EVER have come

y it did — e.g., how an “inflaton” field’s potential got set, or why it evolved and

d converted its energy into particles the way it did. We don’t know ANY of that.)

n’t understand that reaction of being “upset” after reading your post so far.

t’s something else I don’t understand: You seem to imply that we can make

s with both QFT and GR/gravity somehow combined that give us an idea of what

expect as happening “naturally”, when the basic fundamentals of space and time

in the two theories are contradictory, both in their concepts and in the way they

plied mathematically. I thought that the only way to even start to make the

ion” of GR work is to restrict it to 2 dimensions; otherwise, the math falls apart —

hy all the effort has been expended over decades trying to figure out how to

correlate or map a 2D universe to a 3D + 1 universe in some homeomorphic way, as

in other posts. I wasn’t aware that such a combination of theories was required to

sons for expecting “naturalness” in a QFT.)

rstand the hierarchy enigma. I can understand “Oh damn! Guess I was just wrong”

s Nature follows some other pattern, not this one” and “So, Where do we go from

other than the standard (and insulting) ploy of blaming people (like Arkani-

d perhaps even you) for just being miffed, after years of careful work, that their

aven’t turned out to be applicable to the real world, I’m still not sure why there are

rms of actual contradictions or conundrums within the theory, are there if some

ersymmetry isn’t still an option? That is, other than “that’s just the way things

hat’s strange…”, what is it that is being impllied by the lack of (detectable)

etric particles that is so “shocking”?

is the absence of such fields any more shocking than their presence if we were to

fully agree with (and hope everyone supports) the idea of pursuing an idea

, working out its ramifications, seeing where that leads and coming up with

ys to corroborate or invalidate that idea (or parts of it) — even (perhaps

if that process is hard and/or subtle. Whether you think supersymmetry is a

tal principle or not, of course we should explore every avenue to investigate it as a

. But as mentioned elsewhere, I am reminded of 19th century thermodynamics and

of caloric: prominent scientists (and many not-so-prominent ones) spent their


29 of 62 10/21/15 10:23 AM

g up with the mathematics of heat as a fluid. Scientific papers on caloric were still

ten and printed in the first decade of the 20th century, 50 years after the

l theory of heat as kinetic energy of molecules and atoms had been shown to be

rate. Some of that work carried over; some of it didn’t. I also understand the

n “threading the needle” (as you have put it) with new theories that might replace

d GR, while meeting all the constraints that we now know about. I just hope that as

hasis is being applied (and funding allocated) to finding the next “particulate

atter and heat” as in exploring the older ideas that don’t seem to be working out,

ill need to be replaced/modified anyway.


you’re wrong to use the word “upset”. “Troubled” is a much better word. It disturbs

p — it seems that we’re missing something. But “upset” is the wrong word. Yes,

e some people who engage in polemics and call each other names. I bear no

ibility for such idiocy.

the upset that you are perhaps referring to seems to have to do with whether or

ersymmetry is right — and indeed you seem to assume this too in the way you

his comment. But supersymmetry is only one possible solution to the naturalness

perhaps it was once the most plausible, but after the LHC’s 2011-2012 results I’d

now no longer the obvious front-runner. I also bear no responsibility for the people

e and who hate supersymmetry. Those people, perhaps, are “upset”. [Though not

t as the people who love technicolor, which predicts no observable Higgs particle.]

such emotional debates are silly and demeaning to the scientific process. I’m

ed in nature, not my pet theory or someone else’s pet theory. I neither love nor

ividual theories; I just want to know if any of the ones we know actually matches

ack to the issue at hand. I haven’t finished the article, so you’re running way ahead

ame. It takes time and careful thought to appreciate this problem; the typical

te student (for example, me, back in the day) has to think about it and about the

possible solutions to it for a few months before really appreciating just how hard it

lve within a quantum theory. There are only a handful of solutions (all of which I’ll

) and all of them — except a “selection bias” (also sometimes called a “weak

ic principle”, though the use of “anthro-” is misleading) — predict new particles

le at the LHC sometime in its current or future runs.

t me for a moment when I tell you that it’s really hard to solve, and that any

within theories of the class we know would predict new particles at the LHC. If we

’s a selection bias (which is a statement about the whole universe, and therefore

e naturalness criterion derived from decades of study of quantum field theory —

as not failed before, mind you — does not apply, at least not in its strongest form,

ere is a solution to the naturalness problem which violates the known principles of

m field theory (i.e., we must go beyond quantum field theory not just for quantum


30 of 62 10/21/15 10:23 AM

but even for the physics of the Higgs)

ding that at least one of these is the case — which will take a long time — would be

ig deal, conceptually. It would change the questions that scientists ask, and could

major shift in the history of the field — much like the Michelson-Morley

ent was a watershed event (not so widely recognized, though, at the time) whose

on our understanding of nature was immeasurable.

there’s a great deal at stake. I don’t see the point in getting upset about it, but

d? Sure. Maybe the solution is right under our noses and we’re looking right past it

ome young Einstein-II will deliver the solution one day. Or maybe we’re doing the

ets of experiments, and the solution will be revealed accidentally in an experiment

sn’t intended to address the question at all.

September 1, 2013 at 3:55 AM | Reply

average Higgs field value implies small Higgs boson mass, and a huge average

value implies huge Higgs boson mass, which is why of course the LHC thought it

the Higgs. I’m sure you must have explained theoretical reason behind this in one

dding to the Naturalness Article | Of Particular Significance

tember 4, 2013 at 12:49 PM | Reply

ar that deciding what is expected and what is un-natural is 100percent subjective ,

le , for me the most (natural) universe is like ours since in my criteria a universe

pien being is not selected , as you see ….even selection force is subjective.

: there are no solutions to naturalness assumed problem as in fact there is no


subjective your decision that such and such properties are not expected biased by

decision that ANY kind of universe is possible which no theory can prove.


this: what about the QF fluctuations that are extremely tuned to result in the UP ?

say it is extremely un-natural . But what if there exist a selection force that

at relation very very natural ? Our physics cannot tell……


s to solve this problem it must prove the impossibility of a meta-selector

that selects for life/mind friendly cosmos only , rendering all other ones


31 of 62 10/21/15 10:23 AM

( extremely un-natural with zero sigma).

ber 4, 2013 at 11:00 PM | Reply

t Fig. 4: How do you measure the Higgs field’s average value? For electric field,

easure the force on a charge placed in the electric field and calculate the value of

field at the point. Is Higgs field’s value also calculated by measuring the force on a

eptember 5, 2013 at 3:59 PM | Reply

part of this article is very interesting and helped me understand some important

really looking forward to the next part.

eptember 6, 2013 at 12:16 AM | Reply

PE I am not a proverbial pain in the neck for you. That would be the last thing I

rying to comprehend what the vacuum is, why it is black, and why it appears to be

ss when obviously it is something very unique in our physical world. For example;

ds such a physical abuse from supernovae explosions, constant radiation of the

, torquing by the gravity and the mad speeds and spin of celestial objects. Could

write something about the vacuum. It is the BIGGEST body known to us, at least

r universe. I know that quantum fluctuations are happening on a quantum scale,

veryday cup of space that we can see and observe. The virtual particles are said to

in and out of existence so much that this phenomenon is viewed as a constant of a

osmological constant). I deduct from what little I know, that vacuum is a medium,

r or water are here on earth, that can absorb things, store the radiation and make it

self. When physicists observe the virtual particles, they must do that test in some

sed cylinder. Could that be the reason for the appearance of the virtual particles,

ized vacuum is actually experiencing the pressure created by the walls of the

he energies build-up, could be resulting in a creation of fake particles because

space has to move/ flow/ breathe. Is there any evidence that vacuum in space also

hese virtual particles? Has this been proven? Hope you can answer this one,

rbjörn Larsson, OM | September 9, 2013 at 6:23 AM | Reply

uestions, and it has been some days. So short answers:

acuum here, for particle physicists, is the sum of all particle fields. Other fields

her definitions (e.g. low pressure vacuums, astronomical vacuums, cosmological

ot black but can be seen locally as a relativistic black body emitter in some cases.

ruh radiation for accelerated objects; Hawking radiation around black holes; static

acuum is not a body, it is a system of fields. Magnetic _field lines_ snap and

if stressed enough, see Wikipedia – such field lines track existing particle behavior.

particle fields are pervasive, they don’t disappear.


32 of 62 10/21/15 10:23 AM

al particles (a misnomer) is observed through the behavior of the electric field close

ges. See Matt’s articles. You don’t need vacuum for that – I suspect you are

g of particle accelerators which innards are pumped to low pressures for technical

ysics speculations in the rest of the comment are not contacting any of what we

and know about the actual physics. I recommend Wikipedia’s articles on low

e systems and hope they help for the basics.


l, that doesn’t answer my question; Is there any evidence that vacuum in space also

uces these virtual particles? Otherwise we humans/ you physicists are trying to

the nature into your theory. Most of it fits, I hear with exception to cosmological

tant. If it doesn’t fit, discard it. Problem solved To say that quantum fluctuations

eate all space from far, far away galaxies to spaces between the atom and it’s

tron and even further down into the spaces or rather fields of quarks and gluons,

nd any space you can imagine is fine with me. I won’t lose any sleep over it, but

t I see wrong is you people trying to calculate the spaces of the universe you have

eans of verifying. What is the principle here, that energies of the universe have to

nce out? All the positive energy of the fermions (which are just another state of

gy) has to cancel out all the negative energy of the universe, which is the energy of

orces (their fields and bosons). WHY? If these two cancel each other out, don’t you

static universe? This universe is on the go. What’s driving it, forces or fermions?

rmions are energies in another state then everything there is is energy. There is no

to balance anything out. The problem is not in unnaturalness of nature but in

aturalness of an approach. You are trying to solve a problem that doesn’t exist in

re but is created by your way of looking at things that make up the nature of this

erse. First solve the problem of gravity. Is gravity truly the fourth force or is it an

t caused by other factors. In that case universe will have only three forces

ating upon it. Yes, that would make your problem even worse because without the

itons you’d have less negative energy. The ratio could be as low as one to two.

? Due to all the cancellations that different forces have on each other. I think that

re of the nature is not to be precise, but it’s precise enough to hold it’s shape and

hat it’s suppose to do. In your theory though, nature is precise. It’s rigid. That’s

t’s unnatural. If I weigh two ounces or pounds less in a highrise building then when

ch the ground floor, I’m none-the-wiser. Nature has imposed some strange effect

e without me even know it. I’m still me, holding my general shape. Same principle

ies to the universe, I should think. So, the problem of naturalness is man-made.

| September 11, 2013 at 11:57 PM | Reply

n its simplest form there is only one phenomenon which causes all the forces, it’s

he spinning of objects. If you think about it, what other phenomenon it could be?

unniest part comes when you derive a model based on spinning, everything comes

rystal clear. Try it for a fun :)

September 11, 2013 at 11:43 PM | Reply

vacuum here, for particle physicists, is the sum of all particle fields.” Yes, I realize


33 of 62 10/21/15 10:23 AM

, but by a wikipedia’ definition, vacuum is a space free of any matter. It mentions

ect vacuum and partial vacuum. Regardless of that, vacuum suppose to have

uation of energy that can be measured and observed. I don’t question that. If you

physicist, tell me where I’m wrong. If we say that universe can’t have more

tive energy than negative energy, that is assuming that we had a Big Bang. We have

art to visualize another picture of how universe started, the possibility that mater

ped out out of the vacuum itself and that vacuum existed before the matter. The

ent quantum fluctuations could be the end state of the vacuum that could have

a lot denser before. SM is ‘as if’ designed to eliminate the concept of our universe

g created out of the empty space vacuum that might have existed forever. You say;

reated space vacuum. give me some proofs of that. CMBR means nothing of the

. You are looking at magnetosphere of either this galaxy, cluster of galaxies or

erse itself but how can you know for sure which one. The weak radio energies

e nothing unusual, least that BB occurred. Tell me first where all the photons go

don’t get absorbed by matter? Tell me if universe has a magnetosphere or that

e is no difference between the space of our universe and hyperspace or whatever

wish to call it, if multiverse is reality. If BB never happened, then it changes the

re of what reality is. Unless anyone of you physicist is willing to forget for the

ent all you have learned and accepted to be the truth of reality and take a fresh

approach to this universe and nature of it, you may never solve this problem of

ing, (emphasis on seaming) unnaturalness of our universe. Yes, and please don’t

imize the importance of anthropic principle. That’s where your answers are. If you

ost in the detail of the picture, you may miss the whole meaning of it. (Too close to

rees to see the forest?)


it. We don’t know the probabilities for any of this, so where is the problem? It’s

g a melted 20-sided die with the number 20 showing, and exclaiming “huh, there’s

percent chance that this would exist!”.


Matt’s comments above shows that you _can_ estimate the problem:

in the situation of having at best an extremely rough guess at the probabilities, so

, at best, an extremely rough estimate. But when you’re dealing with numbers that

small, getting them wrong by a huge amount doesn’t change the qualitative

ion: our universe, no matter how you calculate it, is very unusual, on the face of it.”


when you make an appeal to frequencies of events (die throws), you would here

n appeal to multiverses.


t’s just the thing, though. You assume that the die was thrown before it melted, or

that it’s a fair die and not one with “20” written on all sides.

what Matt is saying, if I understand him correctly, is that that we don’t know


34 of 62 10/21/15 10:23 AM

ther there were ten thousand sides or ten nonillion sides on the die, but either way

hance of rolling a 20 is pretty low. Again, this is based on the potentially false

mption that it’s a fair die.


h, so you put some significance in the “melted” part. You are speaking of “fair”.

ell, Matt was considering a fair dice, he could calculate rough probabilities within

ur universe. It seems to me it is you that has to demonstrate first if a multiverse

xist (die throws), and then if unfairness exists, and then if it applies to Matt’s

roblem, and then if it is better than Matt’s estimate. Lots of.”if’s” you take upon

n)Naturalness, Explained | Of Particular Significance

ember 9, 2013 at 1:06 PM | Reply

xplanation as usual, Professor Strassler. You really do have a gift for coming up

it of helping you polish this article, I have noted some typos in the most recent

he text adjacent to Figure 5, “It’s as far as one could can push the Higgs field’s

he text adjacent to Figure 8, where you describe someone as being “now a

t the University of Illinois Professor”

an observation – throughout the most recent section, you claim that if vmax is

eV, there is no problem, and that we do not know what vmax is. So isn’t the

lution that vmax is near 500 GeV?

recent section of your article does a good job of convincing me that the naturalness

creases as vmax increases above 500 GeV, but you have provided no evidence that

deed greater than 500 GeV. Is there some reason we have to think that vmax is so

ere really is a problem?


indeed that vmax is near 500 GeV. And if that is true, the LHC will

r as-yet unknown particles, and other predictions of the Standard Model will fail as

e strongest evidence against it — inconclusive at this time — is that the LHC has

discovered any such non-Standard-Model particles, and there are no known

ns from the Standard Model at the current time. Arguably we should have seen

eviations already by now. But I will get to this issue soon.

for catching the typos!



35 of 62 10/21/15 10:23 AM

ctly similar to my comment on the (explained)post , I guess there are some


such thing as a vacuum, so the the real question is do we know what all the fields

w they interact? Therefore each yet to be known particle is an indication of a field

ow interacts with other known and unknown fields? Would a black hole

be in essence, matter broken down to its constituent fields and tied up, or not, or

d into a knot? As to a Creator or not, I have had my own personal experience,

is best not to argue over something that cannot be accepted by many for their own

easons. This should not be a blog about Religion.


s such a thing as vacuum — the universe is much emptier than you think.

ber that only 1/10^15 of the volume of an atom is occupied by the nucleus. And we

ulating the effects of fluctuations whose distance scale is at least a 10^9 times

, in volume, than the nucleus. So the universe has lots of vacuum, on these distance

zen (Jeh-Tween) Gong | September 9, 2013 at 5:08 PM | Reply

andmother of 15th century comes back to see her grand … grandson, the Apple boy.

ing is the conversation about this unnaturalness issue.

G-grandmother, I just read a great article about the unnaturalness of Nature.

ment in it makes sense. But put all together, it just doesn’t make sense to me. How

be unnatural? You have sat right beside Nature for the past 500 years. Can you

other: Oh, the only thing unnatural to me during my last visit in the 17th century

a man who walked on a rope 100 feet above the ground.

It is unnatural to an average person in their ability to perform such a stunt. But, it

llowed by the laws of Nature.

other: Well, I really see some unnatural things in this visit. When I came down

irs, I saw many people in a bird-like metal box flying in the sky. Then, I saw many

ing from a hand-held plate.

Indeed, they are some kinds of unnatural as they were invented by humans. We

rtificial inventions. Yet, they are still parts of Nature as only laws of nature allow

other: Last night, I saw a video about Ptolemy model of the universe, and all stars

g in different patterns. How can a star dance like a dancer? It is truly unnatural.


36 of 62 10/21/15 10:23 AM

That model put the *center* of the universe at Earth, and it is an unnatural way of

deed, that model is unnatural which means *wrong* today.

other: Hi, boy, you seemingly know all answers. Then, what is your question?

Matt showed a vase/table analogy and said that our universe sits at the unnatural

the rightmost picture).

other: Why is it unnatural? For a few hundred years, I have travelled with my

di all over this universe. And, most of the time (99.9999…%), the vase are not

he natural cases as described in his analogy. His saying is true only when my

landed on Earth. There must be some unnatural force around Earth.

Okay, okay. No analogy. But, please read the entire article. The argument is very

ividually, especially about the Standard Model.

other: Hi, boy, it took me awhile to read it. No big problem, but a major confusion.

d Model is unnatural (meaning, it is wrong).

s unnatural (meaning, … nuts).

The issue is more subtle than that. The Standard Model has three parts.

zoo of particles (especially the 48 matter particles) which are verified by tests.

set equations which *fits* the test data by hand-put many parameters into the

reverse-engineering which produced Higgs mechanism.

d Model is wrong (unnatural), which part is wrong?

other: Part A is message directly from Nature. Part B is artificial but works for

ly part C is the suspect of the problem.

But, Higgs boson was *discovered* on July 4th 2012.

other: Indeed, LHC found *something* on July 4th 2012. But, 14 months later, we

en officially established evidence for the Higgs to bottom quark pair decay (which

e *golden channel*) at all.

ument is all about the *mass* of that something (he calls it Higgs boson) vs the

nergy* (he calls it Higgs field) of the empty space.

er model, the mass of that-thing should be [(1/2) of the vacuum energy + some

ation barrier], as that-thing is a blob of [a vacuum state to a new vacuum state]

unsettled issue and thus no need to go into any further.

Okay, let’s put the Higgs issue aside. The unnaturalness can still arise in the case

other: *Possible universes* was a very old philosophical topic. The evolution

* for the universe is zillions (infinite to be exact), but the *history* of the universe


37 of 62 10/21/15 10:23 AM

only one history. That is, there is only *one set* of laws of universe.

iverse* in the article is about having many different sets of laws of nature. They got

om the concept of *fine-tuning*. If a set of laws can be tuned, it becomes many

*Fine-tuning* is definitely a part of nature. If we change the nature constants very

is universe will be dramatically different.

other: Well, this is another major confusion. Nature is very, very precise, locked by

imensionless pure *number*). That is, no *dimension* of any kind can change it.

s looks very much like fine-tuning but cannot be tuned.

Thanks G-grandmother. Now I understand the issue which has only two

ne is unnatural —- Nature or the Standard Model

enzen (Jeh-Tween) Gong | September 10, 2013 at 1:44 AM | Reply

oy: I think that you have swept three very important points off the table by

ning about the Higgs mechanism, didn’t you? G-grandmother.

Higgs (or other) field classes (on, off, on/small)

tum fluctuations of quantum fields, and the energy carried in those fluctuations

It Isn’t Easy to Have the Higgs (or Higgs-like) Particle’s Mass Be Small (the

tion of all different fields and the magic cancellation)

dmother: I was a farm lady, you know. I know everything about *fields*, the corn

e potato field, the sheep field, the dog field, the fish field, … the ocean field, etc..

oy: Come on, G-grandmother. A herd of sheep, a pack of dogs and a school of fish,

dmother: Okay, my bad. Just exclude those then. But, for all other fields (corn or

tnot), I could turn them on or off as I please, by plowing them out or seeding them

u can move this Earth into Mercury’s orbit, I can even turn the ocean field off.

oy: What is your point?

dmother: Just a bit Buddhism here. All those fields are transient phenomena. Their

ff have no importance for the eternal reality. For me, there was only *one* field, the

of the Earth, and it cannot be turned on or off (so to speak). And, this true field is a

er than all those *fields* add together. So, those summation operations of all those

t fields (top quark field, etc.) do not make any difference for the true Daddy field

annot be turned on or off. By the way, if a field can be turned on or off, it cannot be

oy: What is the true Daddy field for this universe?


38 of 62 10/21/15 10:23 AM

dmother: Now, you ask a right question. It is the space-time sheet (field). All

particles are protrusions from the space-time field. When an electron protrudes, it

oy: So, Higgs field is not space-time field. Is there anything wrong with the Higgs

gument in this unnaturalness issue?

dmother: This is the whole problem. The argument implies that the Higgs field is

Daddy field which affects the entire universe. You know, only the true Daddy field

ce-time-sheet) carries the *vacuum energy*. Any other fields also carry energy,

oy: Come on, everyone knows that the vacuum energy is the result of quantum

tions of quantum fields.

dmother: No, the quantum fluctuations of electric field are not vacuum energy.

a linguistic issue, you know. Vacuum is referring to lacking of matter in *space*.

uum energy is about the energy carried by space-field (space-time-sheet to be

If Higgs field carries some energy, it should not be called the *vacuum energy*,

he Higgs field is the space-time filed.

oy: Well, besides of not being turned on or off, what is the other reason that the

ield cannot be the space-time-sheet?

dmother: The space-time –sheet houses *all* fields (including the gravity field),

e as the Earth field houses all plant fields. If Higgs field does not house all fields,

g on or off does not truly make any difference to the space-time-sheet. If it does

ll fields, then it cannot be turned on or off. All those calculations are just games on

oy: Okay, let’s put this Higgs field vs vacuum energy issue aside. The point that the

energy is the result of quantum fluctuations is still important, isn’t it?

dmother: Wow, you got a key question again. We know three facts.

tum principle (fluctuations) is a fact.

um energy is not zero.

bove two facts (a and b) are related.

at kind of relation are they, the cause/effect or the fundamental/emergent? There

tum principle (fundamental) causes the nonzero vacuum energy (emergent).

ero vacuum energy (fundamental) causes the quantum principle (emergent).

oy: Come on, everyone knows that #1 is the answer. But, what is the big deal here?

dmother: This is *the* issue. By selecting #1 as the answer, we are facing the

ralness issue. By selecting #2 as the answer, the Nature cannot be unnatural. But,

e is very deep and cannot be discussed any further here.


39 of 62 10/21/15 10:23 AM


tastic – the way you explain things makes the investment of a little work on the

reader very rewarding, as I am now feeling quite close to really grokking the whole

r years of reading explanations for non-specialists that skirted around the tricky

e logical argument, leaving the reader unsatisfied even after effort. But–and I think

ut–I am finding one key thing elusive and I would enormously appreciate an

ion of this one issue. Why would the non-existence of particle physics beyond the

odel (apart from gravitation) imply that v_max is as high as possible? Tell me

’ll feel able to explain the whole thing to anyone who cares to listen.


sure I’ve understood your confusion yet. If I do understand it: The answer is that it

ost by definition of v_max. v_max is the scale at which the Standard Model is no

a good description of all particle physics. If gravity plus the Standard Model

ed all of nature, then we know what v_max is… it is that huge number that I wrote

ext. Physically, this is the scale of energy above which precise calculations of

ng experiments require inclusion of gravity effects… where gravitational forces are

strong as the other forces. Have I answered you?


nks for your answer. I think in composing my question I misidentified my

pprehension, because me_[today] can’t understand me_[yesterday], and now my

usion about Figure 5 is different (UPDATE: though 24 hours after beginning this

onse I think I’ve got it; perhaps you can verify). Here’s my understanding of it: the

s field has an average value throughout the universe, which, before we measured

ad a range of possible values. The Standard Model lets us work out, for different

ntial values that the average value might take (up to a maximum, v_max, beyond

h the SM ceases to be consistent with observed reality), the contribution to the

gy density of empty space for each of a number of known effects of the Standard

el. These are the blue curves in Figure 5. There might or might not be any

tional, as yet unknown, contributions–these are the red curves, and you’ve drawn

e fictional ones in the second row. Whether or not there are any red contributions,

um of blue and red contributions must correspond to what we observe. And what

bserve is that the Higgs field has an average value of 246 GeV, and the energy

ity of empty space is such-and-such.

, the blue effects are in principle–and, to a large extent in practice–calculable, you

Given that we know now from experiment what the average value of the Higgs

is–246 GeV–we should expect to be able to predict (if the SM is all there is) the

gy density of empty space by performing the calculations for the blue contributions

NE PARTICULAR SLICE OF THEIR CURVE, namely the slice corresponding to

GeV on the horizontal axis. And either that calculation gives us the observed value

he energy density of empty space, or it doesn’t–if it doesn’t, then there must be red

ts that provide additional contributions. The amazing thing is, whether or not we

to invoke as-yet unknown red effects to yield the observed value, that the

rved energy density of empty space is extremely tiny, and there’s no reason that all

e unrelated effects–whether or not there end up being any red effects–should end


40 of 62 10/21/15 10:23 AM

oming so close to cancelling out, given the comparably large individual

ributions both positive and negative. If they hadn’t cancelled out so closely, no

erse similar to that we observe could have existed.

here’s what I did’t get, and now perhaps I do get: once we have observed the

age value of 246 GeV, why do we need to consider what happens all the way up to

ax on your charts? Whatever is to the right of 246 GeV (and to the left of it) doesn’t

espond to our universe. So if there are no red effects, then the consequence is just

the blue effects have to combine to give the observed value, and the value of

ax doesn’t come into it at all. The reason we might care about v_max comes into it

want to answer the question of unlikely it was, with no other assumptions, that

ancellation should have occured: a very high v_max means a very wide range of

ntial Higgs energies, and at the largest of those energies it would be even more

edingly improbable that cancellation should occur. So the higher v_max is, the

ter the coincidence–if you model our universe as having had a randomly assigned

s energy (i.e. considering a multiverse model which leads to anthropic selection

absence of any new particle physics would mean that the limiting value for the

s energy occurs when the top quark gets too heavy for the rest of the Standard

el to work. This is really really really big, and so the absence of any new particle

ics at higher energies means the coincidence of cancellation, with such a wide

e of potential universes to choose from, is that much more startling. And that’s

you’d expect there to be new particle physics revealed at higher energies than we

currently probe: to mitigate the extraordinariness of this coincidence by giving us

e new reason to not have to consider those potential universes with really really

ly energetic Higgs fields.

right in all of that–it was writing the final sentence above that felt like a

kthrough in understanding–then there’s still something slippery to the argument

y mind: it seems that the probability of cancellation has been based on a

ibution of possible universes that all have the Standard Model or the “Standard

el Plus”, but that are allowed to vary by their different values for the energy of the

s field. Why isn’t the choice of this range, and only this range, seen as a little

trary? Thanks for taking your readers’ questions so seriously.


once we have observed the average value of 246 GeV, why do we need to consider

hat happens all the way up to v_max on your charts?”

ou have the logic up-side down. If the theory is correct up to v_max, then we’re

LLOWED to consider what happens all the way up to v_max. And when we do, we

iscover there has to be very delicate cancellation between what we know and what

e don’t know if there’s to be a Higgs field sitting at 246 GeV. Don’t confuse what

e know from experiment (the field’s value is 246 GeV) from our efforts to get the

ight theory of nature (whose equations should predict 246 GeV, or AT LEAST

hould predict that 246 GeV is not extremely atypical.)


41 of 62 10/21/15 10:23 AM

to mitigate the extraordinariness of this coincidence by giving us some new reason

o not have to consider those potential universes with really really really energetic

ot quite. Mitigating the extraordinariness of the coincidence might not change our

bility or reason to consider how the universe would behave with a huge Higgs field

alue [NOT “energetic” Higgs fields — a very different thing]. What it would

ertainly do is make it more obvious why 246 GeV would emerge from our

quations, instead of zero or something much larger. Let me explain some of the

olutions; then it will become clearer what I mean.

it seems that the probability of cancellation has been based on a distribution of

ossible universes that all have the Standard Model or the “Standard Model Plus”,

ut that are allowed to vary by their different values for the energy of the Higgs

gain: “vary by their different values of the Higgs field”, NOT “different values for

he energy of the Higgs field”. Fields have both value (how big is the field at this

oint) and energy (how much energy is associated with the field being this big.)

e’re talking about varying the value up to v_max.

Why isn’t the choice of this range, and only this range, seen as a little arbitrary? ”

f the theory is valid up to v_max, then that more or less sets the range within which

e can do the calculation. (I can see that the fact that I’ve been a little vague about

ow we actually do these calculations is causing some confusion; the article needs

provement.) It’s not arbitrary; it’s pragmatic. Nevertheless, there *is* some

rbitrariness here. But the naturalness problem is so gigantic that other choices

on’t generally make it go away. Only if you make an enormously different choice

an you make the problem evaporate. But successfully justifying that choice would

epresent, in fact, an example of creating a new solution to the naturalness

There are only a few such solutions that have been proposed over the past


Okay. Thanks. One last thing–I wrote: “Why isn’t the choice of this range, and

only this range, seen as a little arbitrary? ” And you replied “If the theory is valid

up to v_max, then that more or less sets the range within which we can do the

But by range, I meant the range of hypothetical universes that we are imagining

ours being chosen from, not only the range of values of the Higgs field. If I’ve

understood correctly, to quantify the degree of improbability of our universe

being just so, you look at how wide a portion of the horizontal axis on Figure 5

results in a universe compatible with existence, and you see that only one in a

gazillion potential universes will work. The range of potential universes you

consider is precisely those that have the Standard Model or the Standard Model

Plus, and that have a Higgs field value ranging from v_min to v_max. But this


42 of 62 10/21/15 10:23 AM

seems (on the face of it, to one particular layperson at least i.e. me) a little

arbitrary, in that your realm of possibilities is unconstrained as to how the Higgs

field value varies within its range, but very constrained in other respect, namely

that the possible universes are all SM universes.

I can’t even begin to imagine how you could enlarge the calculations so as to

encompass every other kind of (non-SM) universes! But wouldn’t extending your

realm of possibilities of potential universes necessarily change the a priori

likelihood that a randomly chosen one is compatible with existence?

| September 11, 2013 at 7:25 PM |

Clearly the precise numerical likelihood that you compute depends on what

possibilities you consider, and we have no idea what options nature had

available, if any. But you notice that by focusing on the Standard Model itself —

not Standard-Model-Plus — I aim to identify an conceptual issue *internal to the

Standard Model* which appears to require resolution by something *outside the

Standard Model*. This is a way of arguing that the Standard Model and its Higgs

field are not likely to be the whole story for particle collisions with energy well

September 30, 2013 at 2:16 AM |

Excuse me for butting in, but SM accounts for only 4% of this universe. Wouldn’t

this unnaturalness problem disappear when new particles are discovered (2015,

CERN) that might describe the dark matter and the dark energy? Universe

appears to be unnatural or, opposite to what was expected and suggested by A.

Einstein. It’s not beautiful, calm, predictable, but wild, unpredictable, turbulent

and much, much bigger. Could this be because universe is open system and not

closed, as almost everyone thinks of it. If vacuum wasn’t created by a BB but

existed just about forever or, at least before this universe, and was much denser

than today, was not switched on but in inert state, why couldn’t particles come

out of this field? We’d need something to switch it on. Say it was a deliberate act,

planned, etc. If we could build a theory on this hypothesis, and it checked out,

wouldn’t we solve this cosmological problem?


,red and green curves, I suppose you are assuming that there is only one Higgs

ne Higgs particle at the currently known values. Does having more Higgses at

higher energies help with the fine tuning problem or make it worse? In other

more Higges buried in high value of v (max)?


y, if there were, say, two Higgs fields, the only thing that would change is that

of my curves (functions of one variable), I’d have to draw functions of two

s. The argument would be entirely unchanged; adding more Higgs fields does not

y natural cancellations, and the problem would now be just as bad.


43 of 62 10/21/15 10:23 AM

tember 10, 2013 at 10:39 AM | Reply

aturalness problem totally dependent on our assumption that the primary cosmic

tals are Fields so that if in the year 2100 it was proved wrong assumption then the

em vanish , or it is itself some kind of fundamental rank problem , in other words ,

ndamental building blocks tied to un-naturalness ?


d to imagine that simply replacement of fields by something else would eliminate

blem, because we know field theory (and its quantum fluctuations) do a

ably good job of explaining particle physics on distance scales from macroscopic

10^(-18) meters, and the naturalness problem arises already at 10^(-18) meters.

Einstein’s new theory of gravity didn’t make it necessary to fix all predictions of

’s theory (i.e., bridges didn’t fall down just because gravity is more complicated

wton thought), a new theory of nature isn’t likely to eliminate the naturalness

— unless, of course, the new theory changes the Standard Model at the energy of

00 GeV (distance of 10^(-18) meters) or so. (Remember that there’s no naturalness

with the Standard Model if vmax is in ths range.) However, if fields were replaced

mething else in the 500-2000 GeV range, we would have expected predictions

antum field theory for physics at the Large Hadron Collider to begin to fail at the

energies. Instead, those predictions work very well.


aybe the un-natural is the field concept despite the correlations between the data


ber “unnatural” means “non-generic”. What’s a “generic” concept?


un-natural concept of field that reality is built on other kind of primaries .


you are mixing two definitions of natural.

ctacular cancellation between known and unknown large quantities is what is

ral. It is not concepts that are unnatural here.

nt is: even if we replace fields with something else, that can only change the

WN large quantities. The known large quantities will still be there… because we

uantum fluctuations of known fields exist and have large energy. That part isn’t

ent on the field concept.


ally a true scientist , honest , sincere and wonderful person Matt.


44 of 62 10/21/15 10:23 AM

s and regards are due to you for your most respectful science.


I’m not sure I understand is how the Higgs particle gets mass. It seems logical that

he Higgs field value increases the energy of empty space and that makes it more

vibrate the field. However wouldn’t the same thing work for any other particle

up quark, etc)? For the other particles the mechanism of getting mass is through

with the Higgs field. Not because changing the electron field value would increase

of empty space. Is that correct? Because my understanding is that if the Higgs

zero, the other particles would be massless – so the zero point energy would not

point energy would give them some very small mass even without the Higgs field?

iggs boson does not need any other non-zero field to interact with, because for the

nough to use the zero point energy to get its mass?


od question. There is a pedagogical flaw here, and you’ve identified it. I have to

bout whether I can improve this. Both your old impression *and* what I’ve said are

, but I agree the relationship between them isn’t well-explained.

fields that we know so far (and this may not be true of other fields currently

n), the mass of the particle is associated with the Higgs field in some way.

er, the story for the Higgs particle is slightly different from the others.

he Fields: The electron field’s average value is zero; this is true of any fermion. The

’s average value is zero; calculation shows that the minimum energy of empty space

hen the W field is zero on average. Indeed, the Higgs field is the only (known) field

ch there’s something complicated to calculate in order to determine whether the

of empty space prefers it to be zero or not.

he Particles: This is the same, in a sense, for the Higgs and for everything else. It is

t particles like the electron get their mass by interacting with the Higgs field. But

es that work in detail? An electron is a ripple in the electron field. That means that

tron field, which is normally zero in empty space, is non-zero as the electron goes

where the electron field is non-zero, it interacts with the Higgs field, which also

o even on average; and the interaction of the two increases the energy in that

Consequently the electron field’s ripple has more energy than it would have in the

of this interaction, and the excess energy is mass-energy, crudely speaking. This is

. The issue is: by how much does turning on a field like the electron field increase

rgy of empty space? The amount by which it increases tells you something about

s-energy of a ripple in that field.

cial thing that’s different about the Higgs field and particle is that the fact that the

ield affects so many other fields and their particles means there’s a complex

y between the Higgs field’s value, the Higgs particle’s mass, and the energy of the


45 of 62 10/21/15 10:23 AM

m fluctuations of the other fields and how they depend on the Higgs field’s value.

cription I gave above of how the Higgs particle’s mass comes about is not unique

iggs, but its relation to this complex curve, which comes from the quantum

tions of other fields, is special.


nk you very much for the explanation.


arding “the Higgs field is the only (known) field for which there’s something

plicated to calculate in order to determine whether the energy of empty space

ers it to be zero or not”:

read that in the theory of the strong interaction (QCD) the vacuum has interesting

cture, too. In particular that there are quark and gluon condensates characterizing

acuum. Wouldn’t these also be due to fields that prefer to be non-zero in empty


ood point. I should have said: “elementary field”. Quark and gluon fields do not

ave any such issue, but composite fields made from a combination of quark and

nti-quark fields, and from pairs of gluon fields, have this issue. I will get into this

ubject when discussing “solutions”.


ewhat confused. You state Vmax is how far you could push the value of higgs field

tolerance of the standard model, but that does not seem to imply the real field has

in fact unless I misunderstand it is deemed to be 246 which is low and does not

nnatural factors – so why do you need to push the foundations of the model that


nt here is not to put the cart before the horse. We have *measured* the Higgs field

6 GeV. But to show that the theory *predicts* this, we need to show that 246 GeV

lly a minimum of the energy. To prove this we must do a general calculation that

first assume that the Higgs field is low. Otherwise we’d be in danger of assuming

e were trying to prove.

’t worry; if we *had* assumed that the Higgs field’s value was small, but that the

rd Model was valid up to vmax >> 500 GeV, then we would simply have

red, by calculation, that our assumption was wrong… and that there is indeed no

m in the low-Higgs-field region at all.



46 of 62 10/21/15 10:23 AM

– but even according to your text 246 does not have to be the absolute but just the

onal minimum so why strain a good model to breaking point?


mm. Not sure I understand you yet. We want to understand whether the good

complete model or not. If it is the complete model, then the

hought experiment of pushing up the Higgs field to large values should be

gitimate. And then we discover that if it *is* the complete model, it actually isn’t

hat good, because there won’t be a minimum in the energy anywhere near 246

eV. Which leads us to think it can only a good model up to around 500-1000 GeV,

nd then we should expect other phenomena to start showing up, or maybe

omething else weird is going on.


Sorry seems Im the one who does not understand but not sure where I go wrong:

There is one higgsfield at 246GeV – correct?

Because its there, there has to be minimum in the energy density at this level – ?

We dont know why but we dont need any unnatural factors to make it so?

If the field were >>500GeV we would need unnatural factors – but it is’nt – why

does the standard model have to hold for for hypothetical fields that do not/ or

may not exist – as an analogy its like designing a car that can go 500mph but

knowing you can never exceed 60mph on the highway

| September 11, 2013 at 12:50 PM |

Ah — do not confuse the Higgs field’s actual value with v_max. v_max is as large

as we *COULD* take the field and still trust our equations. The issue isn’t

whether the Higgs field’s value is >> 500 GeV ; it’s whether the equations

would correctly describe the world if the Higgs field’s value were that big.

Say it this way: Suppose you know a car can go at 500 mph, but you discover the

car is going at 60 mph. Now you want to explain: why is at 60 mph, given that it

can go 500 mph? One way to find out is: try running the car (maybe just in your

mind) at 200 mph, at 300 mph, at 400 mph, at 20 mph, at 30 mph. Maybe you

discover that the engine’s force and friction on the wheels exactly balance at 60

mph: if you try to run the car at 20 mph, it will speed up; but if you try to run it

at 300 mph, it will slow down; and right at 60, it will coast.

But now imagine, for example, that you had a car that could go 500 mph, and

had an engine that was powerful enough to go that fast in the absence of friction.

Wouldn’t you be surprised if it turned out that the engine and friction balanced

when the car was going 0.0001 mph? Our problem is vaguely akin to this.

Thanks for your questions. You and several other commenters are finding a

number of pedagogical flaws. I’m going to have to do a serious rethink of to

reword some of this article.


47 of 62 10/21/15 10:23 AM


Thanks for your patience,

Okay in the case of the car model I have to assume there is a hidden direct

correlation between the car’s speed and the friction, and I suppose this is what

you show in diagram 7, but if that correlation becomes known, would it not

From diagram 5 it would however appear you dont need absolute cancelation as

long as the curve beyond 500 does not dip lower than the point at 246, so if you

have a field that increases exponentially as the first of the blue graphs (would be

interesting to know what field that represents) and it were considerably stronger

than any other field one could postulate that no more potential lowpoints lie

beyond 500+, wouldnt that be a more “natural” assumption?

| September 11, 2013 at 7:15 PM |

It isn’t just an issue of whether the correlation is known; the issue is whether it is

a pure accident, or whether there’s a reason.

As for the second paragraph’s suggestion: if that were the case, then, if there

were no accidental cancellations, then the minimum of the curve would be at

zero, and thus the Higgs field’s average value would be zero and the particle’s

mass would be large — in short, you’d have a world in class 2. Not class 3.

September 12, 2013 at 7:14 AM |

Going through the comments I think I was asking the same as JonW in a

somewhat naiver way and thanks to your explanations to me and also to him I

think I now finally get the picture (more or less). When I say correlation I mean

with an underlying but unknown reason because random would be unnatural

and I guess thats what youre saying too – I suppose somewhat a long shot but if

particles are produced in pairs, maybe universes are also and then could we not

possibly imagine a corresponding “anti-universe” with all fields reversed – if

such two opposing universes were in the process of still separating or possibly

colliding then could this lead to an overall field cancellation and appear locally

similar to the situation that we experience now?

| September 12, 2013 at 10:24 AM |

You could imagine that, but now make equations that actually do it. That’s the

hard part. Then, having succeeded, make a prediction based on those equations.

That, too, may be difficult.


The maths to do that is beyond me, but I would predict that a mixture of

opposing universes would not be very stable, at least not for a sufficiently long

time to get to the present stage



48 of 62 10/21/15 10:23 AM

id that there is no such thing as a vacuum, it was as a question, but in a sense

ield permeate all of space? At some time matter must have sprung from fields at

t in the creation of the universe? Right? Of course that would be the particles that

e Hydrogen and Helium, etc.. You can speak of virtual particles which spring in

existence evidently due to the peaks in waves that fields have, I would think.

looking at from the perspective of how I would visualize an ocean wave peak out

isappear, yet the ocean still fills all space, though we only see the surface. Please

less than knowledgeable questions.


ave said no such thing as empty space, not vacuum, sorry.


The fact that things are cancelling out and the total energy is nearly flat is another

ing that there is some unknown symmetry in nature! And what is that symmetry if

e draw you attention to a recent blog by Sean Carrol where he discusses the early

m dark matter searches which are giving hints of dark matter at 5-10 GeV energy

pointed out that if that turns out correct, then there might be roughly equal

baryons and dark matter particles which might have something to do with baryon

nservation. What kind of symmetry can give rise to equal number of heavier (but

avy) dark matter candidates. And other results point to interacting (Exciting) dark

nting to presence of dark electromagnetism like forces that do not interact with


etry is only one possible explanation. Dynamical effects can cause this also. I will

ing dark matter: again, a symmetry is only one possible explanation. It could also

ark forces and dark particles, see: http://arxiv.org/abs/hep-ph/0604261


have an error in your text. There is at least one theory which haven’t that


ven’t read carefully. There are MANY theories that don’t have a naturalness

, and I am going to explain the most famous ones soon. I will not explain those

only believed in by one person, however.



49 of 62 10/21/15 10:23 AM

I made the decision to take another route (in order to change the paradigm

article physics), experiments it is. My last option so to speak. But blasting small

gh amount of antimatter without high tech lab equipment is going to be

remely* difficult. So wish me luck! :)

eptember 12, 2013 at 1:44 AM | Reply

ne, for example, that you had a car that could go 500 mph, and had an engine that

ful enough to go that fast in the absence of friction. Wouldn’t you be surprised if it

that the engine and friction balanced when the car was going 0.0001 mph? Our

ust an issue of whether the correlation is known; the issue is whether it is a pure

r whether there’s a reason.”

use my bombastic replies to Larson wherein I included all physicists and launched

attack on Standard Model. I think I know what you are saying, but your article is

nical for my understanding of physics. I merely wish to understand the principles

se concepts and can not completely subscribe to SM theory because of the

problem and the BB theory. SM works by and large and is proven with tests but it

universe appear unnatural because, as you explained to “zbynek” the universe is

to include higher energies in Higgs field when it works perfectly well at the much

gies. No, there must be a reason for that. Universe must have more fields operating

aps another force or body of energy that operates on the space. I know you don’t

for other people’s ideas on what could be out there but just suppose that universe

bble floating in hyperspace, that it isn’t a brane either but just an empty space

sing a real source of unimaginable energy. Suppose that energy is seated in the

ur universe and our universe is orbiting this source. Say that we are at a safe

om the radiation of this source, a goldilocks zone but closer and further distances

could be that margin of possibilities that some physicists see as multiverse

Ok, that’s my two pennies worth of contribution to this topic and discussion. I

sics will have to readapt to new concepts, because the old one is ready to be

Tabues in physics are preventing fine scientist like you from exploring other

s. May be with the next generation of scientists, things will begin to move on. No,

e wrong, standard model could be the closest thing to reality of this universe, a

tep forward, but it must not stagnate. I’m truly mesmerized with you taking so

general audience that has no knowledge or very little knowledge of physics. Thank


ot completely subscribe to SM theory because of the singularity problem and the

ndard Model describes all particles and forces *except* gravity. The singularity

hich we don’t even know is an issue) has nothing to do with the Standard Model.

Bang theory (which is in excellent agreement with measurements — I don’t know

u dislike it, given how fantastically well it works) involves both gravity and the

rd Model. If you don’t like the Big Bang theory, you probably dislike the gravity

it, and not the Standard Model anyway. As for the Standard Model alone, if you

ke it, you have some explaining to do: it works for hundreds of measurements. It

t be the whole story — indeed it is unlikely to be the whole story — even for


50 of 62 10/21/15 10:23 AM

vitational physics. But it works extremely well.

pression that physicists are wedded to the conventional wisdom and close-minded

ly wrong. When I go to conferences, there are always many talks that go beyond the

tional wisdom. The particular suggestion that you made (or something similar) has

ly been considered. But the problem is that there are dozens and dozens of such

ions, many far more radical than what you suggest. Almost all of them will turn out

rong; I could fill this blog with all the crazy false ideas that I and my colleagues

d, and it would make this blog impossibly confusing. (Other bloggers approach

e differently.) I tend to report the mainstream, and especially the best-established

the mainstream; I think that is the best way to explain what we think we know.

course, some of what is mainstream now will be discarded someday; that’s certain.

don’t know which parts will be discarded, or why… so we have no choice but to be

, work hard, and wait for experimental or theoretical insights to push us in the


nks Matt, for giving it to me straight. I’m at great odds coming against you, for if I

why can’t SM explain gravity, you’d just say because we haven’t discovered

itons yet. (I could be wrong in my assumptions). Something is truly a puzzlement

, with the theory of particles. We have various fields. Every particle comes as a

le of that field. You say, fermions have zero energy fields. To me this means that

icle mops up the pre-existing field, if particles are ripples in a field. So, if not out of

s field then from a composite field of EM and nuclear (strong and weak) fields.

s field gives mass to some particles but not to Higgs boson which is scalar in

re and has no spin (?) How can a particle exist without a spin? Higgs boson has a

mass but Higgs field is not giving it that mass. Could we say then that Higgs

n doesn’t exist without a collision of hadrons and is a by-product of that collision

that a kinetic energy of that collision produces it.

ularity being mathematical deduction of gravitational force’ capabilities, yes

n’t belong in SM because SM cannot explain gravity with the known particles. I get

, I knew that. I just mentioned it anyways. Why can’t I accept SM? Because its

d on the philosophy that everything in nature must balance out. So we have

icles and antiparticles. This leads to an alternate realities theory, which to me is as

atural as can be. Why do the things have to balance out? That leads to a conclusion

universe came out of zero energy? If that’s not unnatural, I don’t know what is.

t: Multiverse problem: where did the first universe come from? Big Bang theory:

y start, gloomy ending; universe is on a ‘self-destruct’ course. Mankind has no

re since we cannot leave this universe. Scouting the galaxy by manipulating the

ical laws, creating wormholes is a short term solution if achievable. And then

ping out of the incinerating hug of our dying star or, getting wiped out by an

roid or a comet or, by our own means. I think that universe is a much better place

what theory suggests. Yes, Its full of deadly radiation, but something placed us in

fe place. Now, that would be unnatural if nothing else exists but a physical process

olution, (creation and destruction of matter), and we just happen to be an accident

is mindlessness. That to me would be highly unnatural. Otherwise, Standard

el doesn’t bother me at all. OH, I might have a wrong view of physicists as a whole,

you are not in that group, so I’m glad I stumbled on your blog.


51 of 62 10/21/15 10:23 AM

hing you all a positively peaceful, relaxing, rejuvenating weekend!


n with data does mean identity with ontology , plus if we take the agreed upon fact

termination of theories by data can’t we recognize that maybe ontology in its most

tal primary aspect is something totally different than field activities with virtual

o matter how many experiments match our purpose tailored data-match designed


deep grand secret of nature is that it is so constructed that the mind can describe

ny mathematical structures , every one of which matches data and able to predict

tions , that is fantastic interaction between Mind and Nature , it is the interaction

t be ignored anymore .

hat we see in ontological aspects of scientific theories.


e Matt. , I am confused ; is nature un-natural as it is or as we see it or as some of us

n-naturalness relative or absolute or in the category ( maybe , perhaps , it could

ear cut answer , isn’t that science ?


ndard Model is unnatural as quantum field theory experts see it. That is: the

rd Model is a quantum field theory (and quantum field theory applies also to many

stems in nature, mainly those in solid-state physics.) Examination of the physical

s to which quantum field theory applies suggests that our understanding of how

m field theory works is excellent. Among all those systems, particle-like ripples are

n, and there are some that are Higgs-like. If you look at all the other systems, you

nd a light Higgs-like ripple with a mass-energy mc^2 far less than the energy scale

h you find other particles and forces associated with that ripple… or more

ly, the few cases where you do find it are very well-understood, and the principles

ply in those cases don’t apply to the Standard Model. All of this suggests strongly

r understanding of quantum field theory in general, and the naturalness issue in

, on the other hand, is not yet known to be unnatural, because we don’t know

yet. Only if we can show, using the LHC and other experiments, that v_max is

rger than 500 GeV will be able to conclude that nature itself is, in this sense,


y noticed , I am always looking into the global not the partial , so , is it safe -for

he mind – to say as a global absolute fact that the mighty forces of OUR cosmos


52 of 62 10/21/15 10:23 AM

ed in a truly unexpected razor edge equilibrium ?

s , no , we don’t know . Thanks.


not make statements yet about our universe — only about the theory known as the

rd Model (plus gravity) which may or may not describe our universe. Remember:

’t know v_max, and we don’t know yet that it isn’t 500 GeV, with discoveries at the

ber 12, 2013 at 9:14 AM | Reply

re are your articles on the Standard Model (or =partial grand unified theory?) that

s prediction (by calculation) and experimental data? I heard you saying repeatedly

is spectacularly accurate and that sounds pretty good. but I want to see, check,

ate its accuracy one(by calculation) to one (by data/experiment/observation) for

le) concrete specific physical phenomenon. I also want to know where/how/why

aks down and where(under what conditions(range/scale/applications etc.)) it is

h specific (simple) examples. For what applications is the SM useful? Is the SM

odeling/calculating a behavior of a living cell or a molecular machinery inside a

proper simulations does the SM accurately picture/draw photon – molecule

? For example, how a single (or multiple?) photon(s) interact and alter structures

molecules inside a cell?, or how the molecule emits a photon(s)? Does the SM

pletely accurately describe every single moment of how a photon is absorbed to a

uring photosynthesis (with where the energy is localized in which fields at every

Could you point me to such simulation models (CG/video simulation etc.)? Or the

simulations(with real data) by SM which describes/depicts/draws the propagation


find a few hundred things to check if you read

/twiki.cern.ch/twiki/bin/view/AtlasPublic

/twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults

lhcbproject.web.cern.ch/lhcbproject/CDS/cgi-bin/index.php

cds.cern.ch/collection/ALEPH%20Papers?ln=en

l3.web.cern.ch/l3/paper/publications.html

www-zeus.desy.de/zeus_papers/zeus_papers.html

of the results from the last 20 years; there are hundreds more from

inspirehep.net/search?ln=en&ln=en&p=collaboration+jade&of=hb&

search=Search&sf=year&so=a&rm=&rg=100&sc=0

re no known and confirmed large deviations from the Standard Model, and

ly no glaring ones, within any particle physics experiment. That means: agreement

any tens of thousands, of independent measurements (and if you count each data


53 of 62 10/21/15 10:23 AM

s a separate measurement, you’d probably be in the millions). By contrast, if you

heory which is like the Standard Model but is missing one of the three

vitational forces or one of the types of particles that we know about, it would be

ut by hundreds, even thousands, of experiments.

y things in nature that are known not to fit within the Standard Model plus

energy (which you can put into Einstein’s gravity by hand, but presumably that’s

matter (we have ideas on what it might be, but nothing in the Standard Model can

rino masses (which require a small amount of adjustment to the theory — this may


ere’s a separate part of your question: for what phenomena is it *useful* to use

rd Model equations, rather than some simplified version. For photons interacting

olecules, trying to use the Standard Model in its full glory would be impossibly

hoose what you want to study (molecules)

take the Standard Model and derive simpler versions of the equations that apply

study of molecules — giving up details in return for simplicity

then use those simpler equations to study complex molecules and their interaction

rick, and the subtlety, is step 2. You might fail to come up with sufficiently simple

ns, so you can’t carry out step 3; or you might oversimplify and then step 3 won’t

f course, that’s not a failure of the Standard Model; it’s a failure on scientists’ part

of a way to apply it to a complex problem.

ss to say, if you want to check the Standard Model carefully, you check it on simpler

s first! And there it has an incredible track record. And yes, you can derive atomic

, and the interaction of atoms and light, from the Standard Model, although if the

complex you have to rely on computers; and you can go on from there to derive

er techniques for studying complicated molecules, etc.


t, yes, what you say sounds consistent (but just listing papers would not be so

ful). So, I want to see this part “Needless to say, if you want to check the Standard

el carefully, you check it on simpler problems first!” Could you demonstrate a few

le(er, st) cases (readable/understandable for freshman level physics) for 1)SM


54 of 62 10/21/15 10:23 AM

ks well and 2)SM fails? If you do not have time just one good demonstration

paring “calculation” and “experimental data”) for each (1 and 2) are fine. How

t, how the SM draws/simulates a propagation of a photon in vacuum? I hope it is

le enough so that it is easy to generate such animated CG movies in 3D coordinate

time change. I want to see how a photon radiates/moves/propagates (how photon

behave) in 3D CG as time ticks with all the known field values visibly fluctuating

haps with vector and color density representations etc.) in real time. Or, 3D video

esentations(=accurate simulation by SM) of quantum fluctuation in vacuum itself

ld be nice (if possible). Or, how electron field and photon field (with all the known

ulable/observable parameters like field direction, energy/wave localization/shape,

direction of the photon and the electron etc.) behave when a photon is emitted (or

rbed to) from an electron in 3D CG movie with time.


at , the SM does not specify any constant , does not specify any coupling strength ,

ason for three generations of particles , nor any hint for any system of force values

said before , it is only an effective theory meaning a tool for us to calculate


the collapse of hope to produce the above mentioned unknowns via the M-theory

o the power 500 of ensembles are possible and where all hope to find a theory

all cosmic parameters instead of inputting them by hand vanished , even

g new forces and particles via any rout cannot solve that fundamental problem of

parameters generating mechanism , and as such any hope of solving the hierarchy

ay be rendered as a mirage.


There is no reason for this conclusion. What happened to the M theory dream —

ay have nothing to do with the real world — has no bearing on whether the

hy problem has a solution.


it is so , without a theory to specify the parameters of nature we can never explain

n between plank,s mass and W , Z masses , or the ratio of gravity force to other

hat is the hierarchy problem as stated by you , the death of M-theory dream killed

o solve the problem…….so it is so Matt. ……….it is so my friend.


it is logically impossible to construct a mathematical system in which the

of the SM are the variables which solving the system we get their values since then

f meta- constants are required to solve the equations which in turn need hyper-

ding to infinite regression.



55 of 62 10/21/15 10:23 AM

there is a puzzle if you hold the following assumption to be true: “there’s no

ason to expect these unknown effects in red are in any way connected with the

he cancellation of the different terms, the blue and red ones, some kind of strong

ere is such a connection? The reason might not be obvious, but doesn´t it look

ome might say, even “obvious”) that such a reason must (or could) exist?

rought up an analogy, like: Imagine some thousand pieces of metal, all of different

t when you put them all together, you get a car instead of just a pile of metal. Isn´t

e? Well, only if you assume the pieces were created independently of each other.

my question, many thanks for your efforts to explain us this matter.


, I had the same reaction early on in learning about these matters (in which I am

ovice, and a layman). I believe one response often given is that it is not obvious

eason (for cancellation between opposing terms) must exist, because there is an

tive: a multiverse, where each nucleating bubble has its own physics, and anthropic

n effects lead to the values in our unverse being constrained to come so close to

ng, with no further explanation necessary or even possible for things taking on the

hey do in our observed reality.

only half-serious, but I think the analogous reasoning in your example of a car

e: let’s say you are a member of a species that can only exist inside a car. And you

universe where thousands of pieces of metal, of random different shapes and

re created from nothing, thrown together randomly and spewed out into space,

d over and over again without end. You find yourself in a car, wondering just how

got put together and what caused its pieces to fit together just so. It turns out

no good reason that would satisfy you, save that you couldn’t have been there in

t place to ask the question in the Vast majority of assemblages–the fact of your

ce selects from among these assemblages only those, a Vanishing minority, that

ope it turns out there’s more of a reason that this though!


verse is impossible to exist without un-naturalness or hierarchy

tence is not the cause of our universe

erse is not the cause of our existence

re no laws , principles , rules….etc that dictate a similar scale to the energies and

e is the un-naturalness problem? Is it in the mind of the beholder ?


io9.com/did-the-higgs-boson-discovery-reveal-that-the-universe-512856167


56 of 62 10/21/15 10:23 AM


f energies and forces in the universe does not follow our expectations of their

but are chosen to satisfy the attributes of a viable universe ……….. So where is


att. To say that the origin of naturalness problem is naturalism and the physicists

ns that the universe should follow their criteria , but for the cosmos itself it feels no

hatsoever having weak scale 16 orders of magnitude less that plank!s scale

follow the universe not the expectation .

n-Naturalness or A Miracle? | The Way


trassler : In my stand based on many studies and comparisons , the

lness aspect and the hierarchy problems are in reality features of the supreme

f our universe where the problemness is in our concepts not in reality.

aying this that you welcome those who agree with you and those who are not

, not with the scientific part but with the philosophical part of what you say.


e explanation of the most (un-natural) aspect of space , that is , existing of all

ields in a state of complete interconnection occupying same space without

n a global universal shortcircuit of all possible interactions simultaneously

the universe in a state of ultimate chaos ?

Quantum Gravity and Cosmology Conference | Of Particular Significance


vice : please read what any unbiased mind would reach in the pingback link @

lness or miracle , I do respect the writer very much for saying what many refuse to

id the LHC Just Rule Out String Theory?! | Of Particular Significance

an Nature be unnatural? | The Great Vindications

vitonsandagradstudent | September 23, 2013 at 12:30 PM | Reply

me of you may have read that these calculations of the energy of empty space give

ults. This is true and yet irrelevant; it is a technicality, true only if you assume

finitely large — which it patently is not. I have found that many people,


57 of 62 10/21/15 10:23 AM

ists and scientists alike, believe (thanks to books by non-experts and by the

enerations of experts — even Feynman himself), that these infinities are important

nt to the discussion of naturalness. This is false. We’ll return to this widespread

tanding, which involves mistaking mathematical technicalities for physically

effects, at the end of this section.]”

pression that here (and in the section it refers to) that you’re going for a slightly

udience than the rest of the piece, namely the grad-student-just-out-of-QFT

e. If that is what you’re going for, I think the section doesn’t really address the

ource of confusion. You point out that finite theories still have hierarchies, but I

reater source of confusion is why infinite theories are pathological at all. When

re first introduced to renormalization (especially via stuff from the previous

of experts) it’s often stated that the infinities are actual infinities, which are then

luded in the bare values of the relevant constants. Essentially, this is the “why not

mensional regularization?” confusion, which often makes people new to the subject

erstand why divergences are a problem in the first place. I don’t know if this would

rom your primary audience, but you might want to briefly address this particular


still feel that way regarding the second attempt to address this issue at the end of

4gravitonsandagradstudent | September 23, 2013 at 3:32 PM | Reply

t’s the section I was referring to, actually. You mostly emphasize that the issue of

ities is a technical one, and that finite theories also have naturalness problems.

t shows the issue of infinities and the issue of naturalness are distinct, but if

eone started out the section wondering why we can’t just set vmax to infinity/use

reg, that wouldn’t dissuade them.

pose in a way, the counter to that is earlier in the article, in that even if you took

ite vmax seriously you’d just need infinite fine-tuning and thus would be infinitely

atural. While the structure buries this a little since you dismiss infinite vmax early

our current structure works better for the majority of readers. So on reflection I

’t think there’s anything you need to add, besides maybe a quick note for those who

ht take vmax=infinity seriously.


es, in the end, if a young expert-in-training doesn’t understand this point even

fter what I’ve written, he or she is going to have to go through the exercise: take a

heory that has even the littlest bit of physics beyond the Standard Model, even just

ne heavy fermion with a large mass M and a small Higgs boson coupling y; use

im-reg or anything else to get rid of the infinities; and look at how the Higgs

ass-squared depends on M. That fermion comes in and blows everything to


58 of 62 10/21/15 10:23 AM


on one minor point. In mentioning this fine-tuning of the Higgs field or Higgs

,000,000,000,000,000,000,000,000 (to use your number), you say, “Such

ine-tuning” of the properties of a physical system has no precedent in science.”

re seem to be at least two other similar cases of equally amazing “fine-tuning” :

ning of the cosmological constant (vacuum energy density) to one part in 10 to the

er (quantum field theory gives us an expected value 10 to the 120th power higher

ighest value compatible with supernova observations).

ning of the proton charge and electron charge, which match to 1 part in 10 to the

r, something unexplained by the standard model.

gs field fine tuning seems to be not at all a unique case in nature.


ing (1) — I do discuss this, extensively, elsewhere. But the problem with the

ogical constant is that it too is unexplained. We do not have a proof, as yet, that its

alue is due to fine-tuning, so we can’t give it as an example of fine-tuning, only one

fine-tuning. Still, I perhaps should have clarified the wording.

ing (2) — interesting point, but I don’t think this is fine-tuning either. In many

ons of the Standard Model, anomaly cancellations fix this ratio to be exactly 1. If

ere only one generation of fermions, the anomalies would fix the ratio precisely.

s can’t vary; they don’t get quantum corrections. So if a symmetry or geometrical

ship (like anomaly cancellation) fixes the ratio to be 1, it will be forever 1, no

what happens. This is not true for the Higgs particle’s mass, which depends, for

e, on the values of all scalar fields in the universe and on every parameter in the

uantum Field Theory, String Theory, and Predictions (Part 7) | Of Particular Significance

legance, Not So Mysterious | 4 gravitons and a grad student

hat’s the Status of the LHC Search for Supersymmetry? | Of Particular Significance

isiting the University of Maryland | Of Particular Significance

100 TeV Proton-Proton Collider? | Of Particular Significance

hat if the Large Hadron Collider Finds Nothing Else? | Of Particular Significance

May 15, 2014 at 6:32 PM | Reply

w whether it’s just me or if perhaps everyone else encountering problems with


59 of 62 10/21/15 10:23 AM

ite. It seems like some of the text on your content

g off the screen. Can someone else please comment and let me know if this is

ell? This might be a problem with my web browser because

is happen previously. Many thanks

June 21, 2014 at 2:11 AM | Reply

acture and export physics lab equipment / instruments for school, college and

boratory since 1954. We are based in Ambala.clic more

July 7, 2014 at 11:13 PM | Reply

every other wonderful post. Where else could anybody get that kind of

n in such an ideal approach of

have a presentation next week, and

search for such information.

July 26, 2014 at 2:40 AM | Reply

ice. I have a basic question.

fields were present in some empty space. Then quantum fluctuations occurred and

ergy. Then E=mc^2 starts to function. Inflation occurs. And the rest is history.

pty space came into existence at first place?

uantum fields came into existence at first place?

hysics 101: Just Act Natural | The Creation Club | A Place for Biblical Creationists to Share and


e that i noticed yoou visite my web site thus i got here

he favor?.I am trying to in finding issues to enhance my web site!I assume its

ove It or Hate It, Don’t Fear the Multiverse | 4 gravitons

November 17, 2014 at 9:46 PM | Reply

this very informative article. I am eagerly awaiting your take on possible solutions

ural” problem. There is an interesting paper by Moffat that might be worth a look,

Natural SUSY may not be found.

iv.org/abs/hep-th/0610162


60 of 62 10/21/15 10:23 AM

he Anthropic Problem, Entropy, and AI | Random Musings

January 18, 2015 at 6:25 PM | Reply

ikipedia that “As of November 2006, the Standard Model doesn’t work”. This

ain why we have these problems. Personally, I don’t believe in quarks: protons and

re made up of electron, positrons, and neutrinos. Other particles such as the pions,

positrons, electrons, and photons which subsequently split into electron-positron

implies that protons ARE made of positrons and electrons and possibly neutrinos.

explain how radioactive nuclides can capture atomic electrons, emit beta minus

lus – these particles are already in the nuclides (except the captured electron which

e in the nucleus). Shouldn’t the unstable particles and the quarks be removed from

rd Model table and the whole shebang rewritten? This may solve hierarchy and

ess problems and maybe the cosmological constant problem.

March 30, 2015 at 2:56 PM | Reply

mething that still eludes me. Hope you may help.

uite get how do we know that all the contributions, as in Figure 5 add to the green

ay “What We Observe About the Higgs Field and Particle.”

his is not the result of a calculation within the SM, otherwise, why do we need to

ct we know from measurements? Have we observed the energy density, or the

egardless of the momentum cut-off?

April 6, 2015 at 9:40 AM | Reply

at stuff, thanks. I’m a high school teacher and convinced that I have to work this

hat’s the Matter with Dark Matter, Matt? | 4 gravitons

May 26, 2015 at 3:27 PM | Reply

to find your blog: As an Asperger (visual thinker) I find myself trying to explain to

ple” that the brain has the capability of processing information in various

and that individuals can favor using one or more. I became a geologist because I’m

irely a visual processor, despite having verbal skills. Math? Yikes! It’s a language I

erstood, but abstract thinking is difficult. Your posts do an excellent job of

distinctions between terms and concepts which I can grasp as structure and

posted a link to your blog for Aspergers like me. Thanks!

ergerhuman.wordpress.com


61 of 62 10/21/15 10:23 AM

Blog at WordPress.com. The Coraline Theme.


62 of 62 10/21/15 10:23 AM

naturalness and the standard model | of particular significance

Documents