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M-Theory: “The Theory of Everything”

By: Mariam Pitti

Since ancient times human has been searching for answers, for ways to explain all

the natural phenomena and existence per se. From Newton to Einstein, all these great

minds helped us to understand the universe and how it works. However, there was a huge

problem that no scientist could solve, ironically, this is the problem that would give us all

the answers and explain the mechanics of the whole universe. Nowadays, scientists

formulated a theory that could finally explain everything, the M-theory, the mother of all

theories.

Many physicist in the 1900s believed that they had everything figured out, after all

they understood gravity thanks to the Newton’s laws, and they unified electricity and

magnetism thanks to Maxwell’s laws. They thought that they just needed to study few

more things to have a complete knowledge of the universe and basically everything. They

would realize soon how wrong they were (Greene 7). There was a little phenomenon that

scientists could not understand, how light, which they described as a wave, could act or

appeared to be a particle. How could that be possible? They were concerned about that;

however, they believed it was matter of time before someone came out with a logic

theory. They were right! The scientific community was offering a Nobel Prize of Physics to

the brilliant mind that could solve that problem. Einstein was a young and unknown

scientist and he explained with his photoelectric theory, how light could act as a wave and

a particle, according to the special wave-particle duality that it has. The scientific

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community was amazed by this theory, and Einstein would soon gain a privilege position

among them. Unlike what most of the scientists believed, Einstein knew that something

was missing, and in 1915 he presented his Special Relativity Theory, this theory

encompassed their scientific knowledge in a very elegant and simple theory, with this

theory Einstein deduced one of the most relevant formulas of our time, energy is equal to

mass times the speed of light square. However, Einstein noticed that he omitted

something, gravity. Newton described gravity and created his famous formulas about

movement and gravity that we still use nowadays. However, how could Einstein add

gravity to his Relativity Theory? In 1915, he came out with a model that is near to

perfection, the General Relativity Theory, the model of a very neat universe that curves as

a consequence of the masses of the objects (Greene 18-19). How amazing! Einstein

managed to explain gravity for us, or that is what we believed.

There are four fundamental interactions or forces in the universe: the

electromagnetism, the strong and weak nuclear force, and gravity. The electromagnetism

and the weak nuclear force are encompassed together in a single theory called the

Electroweak theory, which also includes the strong nuclear force. However, gravity is way

more complicated than any other fundamental force. Dr. Carlos Herdeiro states that

“Whenever one tries to apply the rules of Quantum Field Theory to General Relativity one

gets results which make no sense. The force between two gravitons becomes infinite and

we do not know how to get rid of these infinites to get physically sensible results.”

(Herdeiro, “M-Theory, The Theory Formerly Known as Strings”).

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Gravity is completely different from the other three forces because is the weakest

force. We know that gravity is responsible for attracting objects with large masses, no

matter what kind of electric charge it may have. Then, how come the other three forces

are stronger than gravity? This example may help one to understand why; if a person

decides to jump from a 15th floor building, when he hits the ground he would not trespass

the ground, this is due to the electromagnetic force, it does not allow the person to pass

although gravity might be pushing him to the ground. This example proves that the

electromagnetic force is billion times stronger than gravity. In fact, if gravity could have

similar strength as the other three forces, the whole universe would be full of black holes,

and no life would be possible (Greene 23). Therefore, it is convenient that gravity acts the

way it does.

Many scientists, including Albert Einstein, tried to explain why gravity is so

different from the other fundamental forces. They needed a way to explain and unify

gravity with the electroweak theory; the problem was that they did not have only one

solution but five solutions, five different theories trying to explain this phenomenon. The

scientific community was questioning the validity of all these theories, after all, how could

they know which one was right and which one was wrong. However, Dr. Edward Witten

showed them that the five theories were just different aspects of the same thing. This

discovery changed everything; he almost predicted the ultimate unified theory, the M-

theory (Greene 67). The M-theory is the combination of five superstrings theories: super-

symmetry, the string theory, supergravity, and p-branes theories. This might be the

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unified theory that Einstein dreamed of (Kaku, “M-Theory: The Mother of all

Superstrings”).

According to the M-theory, the universe is composed of tiny strings. In fact, if we

suppose that the atom has the size of the solar system, a string would only have the size

of a tree on earth (Greene 77). Dr. Pierre states that for the M-theory to be theoretically

valid, eleven dimensions are needed. We know three spatial dimensions, and a fourth one

for time. However, the M-theory requires nine spatial dimensions in which the strings

could vibrate, and the eleventh dimension, the one in which a string could be able to

expand even to the side of our universe or bigger, when they expand this much they are

called branes or membranes (Pierre, “Superstrings! M-theory”). This led us to the

conclusion that our universe is not unique as we thought, but there are infinite

multiverses out there. In fact, our universe could be just one more brane in a hyperspace

full of billions of branes.

What does this has to do with gravity? At the beginning scientist believed that

everything was made of open strings, which means that the strings are attached to one

single brane or universe. Suddenly, they realized that not everything was composed of

open strings; gravity was the only thing that was made of closed strings. This means that

since all matter is attached to one brane it is not able to perceive other multiverses.

Gravity, being the only thing composed of closed strings, is able to travel through all the

branes or multiverses because it has no bonds attached to one brane or another. This is

the reason why it seems to be very weak in our universe; however, it is only a

consequence of its force being divided by all the possible multiverses (Greene 62-64).

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The M-theory sounds great; however, it is almost science fiction. How do we test

it? Until now, the M-theory is just pure math; to test a theory like this is almost

impossible. Since scientist would need to recreate the Big Bang, and well, that is not easy.

However, this magic theory does not end only as a theoretical theory. As crazy as it

sounds, it could be tested (Kaku, “M-Theory: The Mother of all Superstrings”). CERN

(European Organization for Nuclear Research) located in the Franco-Swiss border, has one

of the most ambitious physics labs in the world. Their eighty million dollars particle

accelerator, the Large Hadron Collider, might prove whether the theory is right or wrong.

The LHC consist of colliding particles, the collision creates other particles, maybe new

predicted particles, as it has been doing so far; not only that, but also, it could show if

there are other dimensions by following the pattern of the particles. If they could find the

graviton, the gauge boson of gravity, that would be the Saint Grail not only for science,

but also for the entire knowledge and understanding of the universe of mankind (CERN,

“Why the LHC”).

The M-theory might be the unified theory every scientist dreams of, an ultimate

theory that explains how the universe works. As Dr. Michio Kaku says “This new M-theory

has solved a series of long-standing puzzling mysteries about string theory which have

dogged it from the beginning, leaving many theoretical physicists gasping for breath.”

(Kaku, “M-Theory: The Mother of all Superstrings”).

What would happen if the experiments show a totally different unexpected result?

There is nothing to be worried about, because after all that would be the beginning of a

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new science, a new kind of physics. In fact, that would show us just how complex our

universe is, or maybe multiverse?

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Works Cited

CERN. “Why the LHC.” European Organization for Nuclear Research. 14 Sep. 2008. CERN.

12 Mar. 2012 <http://public.web.cern.ch/public/en/lhc/lhc-en.html>.

Greene, Brian. The Elegant Universe. New York: Vintage Books, 2000.

Herdeiro, Carlos. "M-theory, the theory formerly known as Strings." Cambridge Relativity

and Cosmology. 9 Jun. 2009. University of Cambridge. 27 Feb. 2012

<http://www.damtp.cam.ac.uk/research/gr/public/qg_ss.html>.

Kaku, Michio. "M-Theory: The Mother of all SuperStrings." . 8 Aug. 2008. Explorations in

Science with Dr. Michio Kaku. 27 Feb. 2012 <http://mkaku.org/home/?

page_id=262>.

Pierre, John. "SUPERSTRINGS! M-theory ." Stanford University. 23 Oct. 2010. Sukidog. 27

Feb. 2012 <http://www.sukidog.com/jpierre/strings/mtheory.htm>.