Anything Smaller Than Quarks and Leptons?

[Nicholas Kang]

Is there anything smaller than quarks and leptons?

[Strange]

They are all point particles so "smaller" doesn't really have any meaning.

[hoola]

aren't there supposed to be "strings" that makeup the quarks?

[Strange]

aren't there supposed to be "strings" that makeup the quarks?

 

According to string theory. But there is no evidence for such things yet.

 

There are also various theories about smaller particles making up the fundamental particles:

http://en.wikipedia.org/wiki/Preon

But, again, no evidence for any of these.

Edited June 6, 2014 by Strange

[ajb]

Is there anything smaller than quarks and leptons?

As others have said, smaller here is not the best choice of words.

 

We can think of energy as being inversely proportinal to length. Thus by smaller you could really mean is there anything at higher energy scales?

 

Well this seems to be an open problem. There is such a thing as the particle desert, which refers to the energy gap between the TeV scale, which we are probing now, and the GUT scale. The GUT scale is the energy at which all the forces of the standard model will unite (if we include supersymmetry). This scale is something like 10^16 GeV.

 

So maybe not much happens until we are near the GUT scale or maybe there is something in this desert. There could be new physics and so new particles before we get to the GUT scale. But we have not probed this yet and so it is speculative.

 

The natural energy scale of string theory is the Planck scale, which is higher again. This is the scale at which quantum effects of gravity become important.

Edited June 6, 2014 by ajb

[hoola]

and couldn't the strings be "strings" of numbers in specific algorithmic arrangements, if the universe is a mathematical object, as per Tegmark ?

Edited June 6, 2014 by hoola

[ajb]

and couldn't the strings be "strings" of numbers in specific algorithmic arrangements, if the universe is a mathematical object, as per Tegmark ?

I don't know what you mean here.

[hoola]

I mean that the "strings" of string theory are composed of a series of finite number sets, describing in their formulae, a specific force or material and how or if it reacts with the other particular "strings" that come into proximity...

[ajb]

I mean that the "strings" of string theory are composed of a series of finite number sets, describing in their formulae, a specific force or material and how or if it reacts with the other particular "strings" that come into proximity...

String theory is a particular 2d sigma model, that is we have maps from 2d source manifolds, usually R^2 or S^1 x R (open or closed strings) to 11d space time.

 

How does this relate to what you have said?

[Nicholas Kang]

I did rethink my question. It seems that there is no final answer to this question. You see, if string is the smallest thing in the world, then what is the composition of string?

[ajb]

You see, if string is the smallest thing in the world, then what is the composition of string?

If the string is fundamental, then the string is "made of string". It would represent the basic building block of all matter and forces.

[Nicholas Kang]

How can it be possible that string is made of string? It sounds ridiculous. How can you prove that string is fundamental? If string is fundamental, then what is the composition of fundamental string?

[Sensei]

I did rethink my question. It seems that there is no final answer to this question. You see, if string is the smallest thing in the world, then what is the composition of string?

 

What is composition of bit? (in computer sense)

 

We know that it can have value 0 or 1 (kinda like property of bit),

and we know its address (kinda like position of bit).

We can read bit, write bit, compare two bits, store it on disk, restore,

group them to byte (8 bits), short (16 bits), long (32 bits) etc.etc.

 

I am not saying that Universe is some kind of database or so. Universe is "alive". Particles interact constantly.

But as you can see in above example, not everything has to be made of infinitely smaller things.

Bit is unbreakable. It's fundamental.

[Nicholas Kang]

From my perspective, bit is abstract, or simply a measurement. 1 bit on computer is a measurement of how much information is stored in your computer. The same as length, say 1 meter. 1 meter is 1 meter? Not so, maybe 1 meter can be made up of 1cm, 1mm, 1micrometer and so on. If you have bit, maybe you can have millibit, centibit and so on. Secondly, a measurement is a point of view, not the object itself. Your table is 1 meter wide, you measure it as 1m wide. Are you sure that the table knows itself as 1 meter wide? 1meter is abstract. Table is concrete. Table is made up of atoms. Atoms are made up of protons, neutrons and electrons. Protons and neutrons are made up of quarks, while electrons are leptons. Quarks is made up of string. You can measure how long and wide and big and the size of string. You measure it. If let say string is 1 meter, than what will you see if I say I want to see the 1centimeter in the string? I can somehow separate a string into tiny pieces? In my opinion, to know the composition of string, you can only use a particle accelerator and smash two string then examine the remnants. How is it possible to separate string? It seems impossible to do so.

Sorry to tell you, Sensei. Please note that the quarks are changed into string in the above paragraph.

Edited June 9, 2014 by Nicholas Kang

[Sensei]

No, you cannot have mili bits. You can't even have half of bit.

However you can have integer multiply of bits.

You can have Mega bit for instance (typically used in network transmission speed Mbps = Mega bits per second).

If you have 1 GB of memory stick, it's 8 * 1024 * 1024 * 1024 = 8589934592 bits.

 

It's similar case, from other discipline, as in physics quantity of electrons, protons or neutrons that must be integer number. You can't have half of electron, half of proton, half of neutron.

 

Quarks is made up of string.

 

That's assertion. Quarks could be theoretically made of something smaller, but not necessarily strings.

String theory is just one of many theories.

Difference is that it has many (theoretician) scientists on its side.

That does necessarily make it more plausible/probable.

Simply it's well known by public (from just name mostly). Ask people for string theory math..

 

 

You can measure how long and wide and big and the size of quarks. You measure it. If let say quark is 1 meter, than what will you see if I say I want to see the 1centimeter in the quark? I can somehow separate a quark into tiny pieces? In my opinion, to know the composition of quark, you can only use a particle accelerator and smash two quarks then examine the remnants. How is it possible to separate quarks? They are held strongly by strong nuclear force. It seems impossible to do so.

 

It always looks impossible, until somebody invent a way to do it.

And then get Nobel prize..

 

BTW, look at neutral pion particle decay mode.

http://en.wikipedia.org/wiki/Pion

Edited June 9, 2014 by Sensei

[Nicholas Kang]

Why I can`t have millibites?

[Sensei]

Why I can`t have millibites?

 

http://en.wikipedia.org/wiki/Bit

[Nicholas Kang]

Anyway, I don`t mean half a proton. I mean a fraction of proton which is made up of 2 up quarks and 1 down quark. Which, actually, means quarks. How to determine the length of a quark. If a quark is 1 meter, than, we should be able to further divide it into 100cm, and for each 1cm, we can even get 1mm and for each 1mm, we can still get... Infinity. That`s why I suppose that there is no possible answer to this question.

if bit can be 0 and 1. It is still a value of measurement. 1 bit is just an example, unlike daily measurement such as length, meters. If a string is 1 meter, I can further divide it into 1 cm,1mm and so on. If you treat this case as in bit. Then it seems like string can only have two values. That doesn`t make sense in the context in which I want to measure how small string is but you tell me that it has 2 values. And the values can only get bigger, not smaller, thus no millibite but gigabite, megabite are present. So in the effort of measuring string, you can only measure 1m, 1km, 1Gm and so on but no such thing like 1cm of string or 1mm of string division. I mean divide and explore what is inside string.

Edited June 9, 2014 by Nicholas Kang

[Sensei]

If you will make f.e. 1 undividable length unit 1 femtometre (10^-15 m) everything what we know (especially macro scale & cosmic scale) will appear really big.

Atom of gold has diameter ~288 pm = 288*10^-12 m.

So 288*10^-12 / 10^-15 = 288000 base units.

 

Visible violet photon has wavelength 400 nm.

From perspective of 1 femtometre, it's 400,000,000..

Edited June 9, 2014 by Sensei

[Nicholas Kang]

We don`t care this. Of course, imagine you are an atom. You think that you are big, bigger than protons, neutrons and electrons but when I tell you atoms combine with atoms to form molecules. Then, you will be surprised. At that particular moment, you are small and many of "you" make up the world, that`s why you will see the universe appear really big.

[ajb]

If string is fundamental, then what is the composition of fundamental string?

If a string is really fundamental then it cannot be made out of anything else. That is what we mean by fundamental, it has no internal structure.

[Nicholas Kang]

Then, we should revolutionize this statement. So, the word fundamental is not suitable in this context. It sounds crazy to assume something cannot be made up of anything else and no internal structure. In macroscopic world, we can easily find out the internal structure of objects. In microscopic world, it must be possible to find out internal structure of objects too. No such thing fundamental then. Because curiosity is always there, what is inside fundamental? You get crazy with this endless question, so, endless fundamental.

[ajb]

Then, we should revolutionize this statement. So, the word fundamental is not suitable in this context. It sounds crazy to assume something cannot be made up of anything else and no internal structure.

If we take this to be true then there is no notion of anything being fundamental as any entity can always be broken into smaller and smaller pieces ad infinitum.

[Nicholas Kang]

How can it be possible to stop curiosity? It is hard to believe that at a point, anything is fundamental. You mean, people must believe in what scientist say and then no notion would emerge?

Do tell me other alternative theories apart from the string theory. Thanks.

[ajb]

How can it be possible to stop curiosity?

Why have you asked this?

 

It is hard to believe that at a point, anything is fundamental.

Sure, I can understand that. But if nothing is fundamental then we could just keep going on breaking stuff down into smaller and smaller pieces for ever. That to me sounds more unreasonable than having some fundamental building blocks. However, nature has to decide this and all we can do is look.

 

You mean, people must believe in what scientist say and then no notion would emerge?

You don't have to blindly believe what scientists say, but there should be some element of trust here. Not that I am sure it is relevant to the discussion here.

 

Do tell me other alternative theories apart from the string theory. Thanks.

I don't think there really are many alternatives to string theory as a unification scheme and fundamental theory of matter and forces.

 

Maybe Alan Connes work on noncommutative geometry and how the standard model can be included in this could count.

 

Garrett Lisi's E8 theory we could include, though that is now thought that it cannot work for some technical reasons.

 

Theories that just use point-like particles tend not to work very well here and are taken as effective theories.

 

Slightly less encompassing are works on quantum gravity like loop quantum gravity and causal set theory. However these are not usually seen as unification schemes.