ALL YOU WANT TO KNOW ABOUT SUBATOMIC PARTICLES BUT ARE AFRAID TO ASK

ALL YOU WANT TO KNOW ABOUT SUBATOMIC PARTICLES BUT ARE AFRAID TO ASK

and your kids!

A quick guide for the parents of curious kids

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Discovery of the Higgs boson and the buzz around the event has embarrassed lots of geek parents. Being a scientific guru for your children means keeping up-to-date with what is going on. It is not easy when science is moving at such a pace as it is right now. And it is made even more difficult if one needs to deal with quantum physics and the mysterious subatomic world.

No matter how strange this world is, it is also, without a doubt, extremely interesting. We have put this short guide together for those parents that don’t have a PhD in physics but would still like to tell a true, if simplified, story of the unseen world of elementary particles. No matter how strange it sounds, reading these questions with your kids might be a very entertaining way of spending time together. Enjoy!

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The strongest electron microscopes are capable of seeing things that are

hundreds of thousands times smaller than a body cell. But still, this is not enough.

With this equipment even a single atom can be seen. But there is no way to look

inside the atoms where there are particles that are hundreds of thousands of times

smaller again! It’s amazing that we actually know that, without actually seeing it!

Well, they are small. I mean, seriously small. They are so small that they

can’t be seen at all. Only the best optical microscopes, fluorescence microscopes,

can see the detailed structure of your body cells. As is well known, the cells are tiny.

They are tens of thousands of times smaller than a grain of sand. This microscopes

are so good that the inventors got a Nobel prize in 2014 for their work, but comparing

to atomic scale they were far, far away from the point.

How small are the smallest particles?How small are the smallest particles?

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Atoms were claimed to be the smallest elements in the world. For centuries people imagined them as small spheres of matter that are “glued” together to form more complex stuff. But the atom was not to be divided. All the way into the late nineteenth century, that is. At that point the first subatomic particle was discovered. It was called an electron and we now know that it is responsible for the phenomenon of electricity.

So what is inside the atom?So what is inside the atom?

For a few years people believed that inside the atom the electrons orbit

around the nuclei, similar to planets orbiting around the sun. Then scientists

discovered that nuclei are made from protons and neutrons and started to smash

them against each other. And the fun began! Why? Because after the collisions

they found out that there are even smaller particles and that they behave strangely,

and that the whole world needed a brand new way to describe it. This is how the

Standard Model was born.

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This is a theory about how the world on the smallest scale is built. It

names base forces that work a on subatomic level. It also names the elementary

particles from which all matter and antimatter is made. It is regarded as a theory of

almost everything. Scientists have not been able to find a way to claim it is wrong.

Funnily enough, any experiment that is run based on this theory proves this with

unexpected precision. Some of the particles predicted in this theory were actually

discovered much later. Like top quark, tau neutrino or the recently discovered Higgs

boson. But wait ... there some phenomena which require extension of the Standard

Model and then additional particles are predicted.

What is the Standard Model?What is the Standard Model?

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It depends on whether we count the ones that have been proven to exist

in experiments or we expect to exist based on some theory. Let’s stick to the

first definition. If we count all the types and variations of the elementary particles

we will end up with the 30! That is a lot comparing to the original elementary

particles (proton, neutron, electron and photon)! They could be divided into two

large families: fermions and bosons. In simple words the difference is that the very

same bosons can exist in the very same place whereas fermions cannot.

Still unclear... Well... The Standard Model is based on Quantum Physics.

It is, to put it bluntly, not based on common sense. The rules allow two bosons to

coexist in the very same state. In fact, they are indistinguishable from each other.

In opposite to fermions that behave much more like we would expect (not the

same particle in the same time in the same place, which is logical and very polite

of them). Bosons work as force carriers and we can match all the forces we know

on this scale to have corresponding boson particles.

How many elementary subatomic particles do we already know?

How many elementary subatomic particles do we already know?

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Nowadays we know four of them: such as electromagnetic, strong and weak force and gravity. However, gravity is still unclear. We can name and detect bosons that works with rest of them. Photon is the boson that carries electromagnetic force. This is exactly the same one that is responsible for carrying light. So, it might be no surprise that light is a form of electromagnetic interaction. Other bosons like Boson Z or Boson W are responsible for weak force and Gluons are responsible for strong force interaction inside the atom nucleus. Even the Higgs particle is a kind of boson, though somewhat different. All of them interact with at least some of the elementary fermions.

What are the forces in thesubatomic scale?What are the forces in the subatomic scale?

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Definitely. At least one of them. I am pretty sure you know what an electron

is. If you are lucky you might also have heard about quarks. There are 6 different

quarks and similar to electrons they have an electric charge. Three of the quarks

are positive: up, charm and top and three are negative: down, strange and bottom.

An electron is also negative. There are two additional particles alongside electrons

within the charged leptons family: tau and muon, and both of them are negative.

There are chargeless leptons as well and they are called neutrinos.

But what is fascinating is that all of these particles have their antiparticles.

Yes! They seems to have all the same properties except one that has a opposite

sign. In the case of electrons it is an electric charge. A particle that behaves as a

positively charged electron is called a positron and is actually an antiparticle of an

electron. When they meet they are annihilated. Literally. There were two particles-

blink- no particles... Just some energy being produced in the form of at least two

photons. No doubt physicists love these kinds of experiments! (Remember, blowing

things up is science if you note the effects down).

Elementary fermions? Do I know them?Elementary fermions? Do I know them?

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No! Even now we know that there are things that humans’ most sophisticated

theories can not yet grasp. It doesn’t really include gravity. Yeaah! We still don’t

know exactly why the apple drops from the tree! It can say nothing about the Dark

Energy and Dark Matter that we knew exists within the Universe. Theoretist are

working on an extension of the Standard Model (such as Supersymmetry) but, at

the moment, the Standard Model is the king. But who knows for how long!

Is the Standard Model complete?Is the Standard Model complete?

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Well, this is just the beginning of this wonderful journey through the subatomic particle world. Below you may find a quick puzzle game to check which of you: grown-up or child has so far remembered most from this hidden universe:

Are there neutral leptons?

They are called neutrinos!YESIs the Higgs particle a boson?

Not exactly the same as e.g. a photon but still in the same familyYES

Is antimatter real?

We can even see how it annihilates real matter.YES

Are atoms visible with light?

Not with light, you need electron

beams to look at matter on this scale.NO

Is a Proton an elementary particle?

For long time people claimed so,

but now we know that it consists of quarks.NO

Is gravity defined in the Standard Model?

Not really as we are still missing the

discovery of graviton (which would prove gravity definitively).NO

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Is the Neutron part of the atom nuclei?

Along with the proton it forms a nuclei,

however both are not really elementary

particles but are build up from quarks.YESIs a photon a particle that

carries light?

Along with any other electromagnetic force interactions.YES

Is there something like a top quark?

It is the latest quark discovered so far… and the heaviest, by the way.YES

Are quarks electrically charged?

All of them! Some are positive and some are negative.YES

Is the strong force stronger than the weak force?

As expected, I guess. A bit of a trivial one :)YES

Is neutrino part of the atom nuclei?

But it is easily confused with a neutron.

Scientists, being constantly busy, rarely

have time for inventive naming.NO

Is there something like Dark Side of the Force?

At least physicist don’t believe so. However,

they do agree that Dark Matter or Dark

Energy might have it’s place in the Universe.NO

Do Gluons carry a weak force within an atom nuclei?

Gluons carry strong force and are

actually a GLUE that keeps the quarks togetherNO

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This ebook is a part of the Publish or Perish project. We aim to develop the first hybrid boardgame for little scientists! To learn more, visit us at:

PublishOrPerishTheGame.comPublishOrPerishTheGame.com

©2015 Copyrights by Rombo Games LTD This work may be reproduced and redistributed, in whole or in part, without alteration and without prior

written permission, provided all copies contain the following statement: “© 2015 Rombo Games LTD. This work is reproduced and distributed with the permission of the Rombo Games LTD.”

Rombo Games LTDKendals Close 35Radlett, England WD7 8NQUnited Kingdom

Project supported by The Henryk Niewodniczański Institute of Nuclear Physics of the Polish Academy of

Sciences in Kraków.

Publish or Perish is a game that combines different techniques, traditional cards and new mobile devices. But the main advantage of it is, that it allows the players to become scientists discovering properties of the building blocks of our world. One can learn about elementary particles and then plan some experiments and analyse their results. Players are trying to determine the values of new properties of particles, which were not even imagined by scientists yet. Like in the scientific world the findings are published. Both cooperation and competition is possible which gives additional flavour to the game.

dr hab. Krzysztof Woźniak, prof IFJ PAN