The smallest particle

[herme3]

I was wondering if anyone has found the smallest particle yet. I know about protons, neutrons, and electrons. I've also heard of quarks, but I don't really know what they are. How far does matter break down? Have they found the smallest particle?

[ydoaPs]

quarks, electrons and their respective families are the elementary particles. according to the standard model, they are point particles. for those that don't know, that means they have no dimensions; no length, width, or hight.

[noz92]

I think the smallest particle would be the superstring.

 

quarks, electrons and their respective families are the elementary particles. according to the standard model, they are point particles. for those that don't know, that means they have no dimensions; no length, width, or hight.

 

I think you're wrong, I believe that elementery particles have a highth, and possibly a width (if I understan A Brief History of Time correctly).

[ydoaPs]

nope, zero dimensions. strings on the otherhand, have 1. if you can't tell, i like string theory(one of the few here).

[noz92]

You would think that they would have less dimensions the smaller they get.

[JaKiri]

for those that don't know, that means they have no dimensions; no length, width, or hight.

 

Not necessarily. They do not necessarily not have dimension, we just haven't measured any, and it makes sense for them to be point mass/charges.

 

I think you're wrong, I believe that elementery particles have a highth, and possibly a width (if I understan A Brief History of Time[/i'] correctly).

 

Forget everything from ABHOT. Read The Elegant Universe by Brain Greene instead.

 

The particles size is effectively measured by their mass, as that dictates how 'spread out' they are by quantum uncertainty. Whether they have actual dimension is neither here nor there; that they don't is a personal conjecture, not actual theory, but it makes sense.

[fuhrerkeebs]

quarks, electrons and their respective families are the elementary particles. according to the standard model, they are point particles.

 

No: http://arxiv.org/PS_cache/hep-ph/pdf/0111/0111302.pdf

[swansont]

No: [url']http://arxiv.org/PS_cache/hep-ph/pdf/0111/0111302.pdf[/url]

 

Yes. String theory is not part of the standard model.

[Crash]

Not yet, that is....it seems to me the way to go though...the mathamatics are perfectly sound and,

wait is fermilab up and running yet? can they pr0vide any evidence for or against M-theory? (string theory)

[Severian]

Yes, quarks and leptons are point particles as far as all experimental evidence so far shows, in the sense that their size is less than about [math]\hbar c /100GeV \approx 0.2 fm[/math].

 

Of course, if string theory is true, then they are not point particles but are composed of strings, but there is no evidence for that yet.

[ecoli]

How could something not contain any dimensions in a 3 dimensional world. I could be wrong, but I'm inclined to think that we simply do not have a device to measure l,w and h, so we assume it doesn't have any.

[JaKiri]

How could something not contain any dimensions in a 3 dimensional world.

 

Very easily.

 

I could be wrong, but I'm inclined to think that we simply do not have a device to measure l,w and h[/i'], so we assume it doesn't have any.

 

Unless we can prove that they're point masses (this isn't as truistic as it appears), the only thing we can do is put limitations on their size. This is what has been done.

[YT2095]

just out of curiosity, would the Photon qualify at all?

 

It`s often refered to as a particle and it has no mass.

[swansont]

just out of curiosity' date=' would the Photon qualify at all?

 

It`s often refered to as a particle and it has no mass.[/quote']

 

A photon has an associated wavelength - it can be viewed as a wave packet. It's a particle in the sense that it has a quantized amount of energy, but it's not a point particle, as the associated electric and magnetic fields extend into space.

[YT2095]

and by Point Particle, does that mean it`s "solid" or "tangible" for wants of a Much better word(s)?

 

sorry if these seem very Basic questions, I AM interested though

[ecoli]

Very easily.

 

Can you eplain this, or provide evidence??

[JaKiri]

Why does something have to have volume to have an impact on the universe?

 

More to the point, how can it be impossible to split something which has volume?

 

The latter isn't that great of a problem, but that's not the point; there are areas of uncertainty for both assumptions.

[1veedo]

nope, zero dimensions. strings on the otherhand, have 1. if you can't tell, i like string theory(one of the few here).

The electromagnetic spectrum goes smaller then a hydrogen nucleolus. This is why we can “see” atoms. I know it used to be taught that we would never be able to see them, and indeed we cant in our normal color range, but this is one of the cases where scientific ‘fact’ is later discovered false.

 

Although I’m not positive (not big on quantum field theory), depending on the model, point particles can get much ‘smaller’ then the quark. I may be wrong so I’ll probably google a bit to find the answer.

Not yet' date=' that is....it seems to me the way to go though...the mathamatics are perfectly sound and,

wait is fermilab up and running yet? can they pr0vide any evidence for or against M-theory? (string theory)[/quote']M-Theory is not the string theory. It’s the most popular yes, but there are others.

[1veedo]

Yes' date=' quarks and leptons are point particles as far as all experimental evidence so far shows, in the sense that their size is less than about \hbar c /100GeV \approx 0.2 fm.

 

Of course, if string theory is true, then they are not point particles but are composed of strings, but there is no evidence for that yet.[/quote']Yeah, Severian was right.

 

There are other “smallest particles” beside them though. Apparently requiring more point particles or strings.