Question about photons

@ogb
You know the theory of force carriers don't you? A photon is a force carrier but it is a wave. So it is not a force carrier because it is not a force carrier?

@ogb said
@sonhouse

gravity is a wave, so there are no Gravitons..

Any physical system with waves propagating has a corresponding particle. So a better sentence would be: "We have detected gravitational waves so we expect gravitons to exist."

@deepthought said
Any physical system with waves propagating has a corresponding particle. So a better sentence would be: "We have detected gravitational waves so we expect gravitons to exist."

Gravitons are the smallest particles of the ether, right? Not to be confused with a photon or electron, those are not the kind of particles you are referring to, right?

@metal-brain said
Gravitons are the smallest particles of the ether, right?

WOW you are confused!
Stop keep making up your own delusional ignorant crap up and just for once at least TRY and learn what the science says.

@metal-brain said
Gravitons are the smallest particles of the ether, right? Not to be confused with a photon or electron, those are not the kind of particles you are referring to, right?

In quantum field theories each field has an associated particle. A quantum of the electromagnetic field is known as a photon. For the weak force the quanta are the W and Z particles, for the colour force it is the gluon (see side note below), and similarly we expect the gravitational field to have an associated particle which is known as the graviton.

The matter fields have quanta we call electrons, muons, taons, and their associated neutrinos and there are the quarks. There is also the Higgs boson. In the quantum field theory picture the particles are pointlike, it's not entirely clear what you mean by size. However, there is a concept called cross-section, which in a classical picture is the area presented by a target. The quantum picture is a little more complicated but it is the effective area a particle presents for scattering.

Gravitons couple very weakly to matter, on the scales we can access in accelerators gravity is by far the weakest force, to the extent that we can't actually detect it. This means the cross-section is tiny. So, interpreting "size" as "cross-section", yes gravitons are the smallest particle.

Side note: I would call this the strong nuclear force, except that the term is ambiguous, it could refer to the force that binds nuclei together, or the force that holds nucleons together. The quantum field theory that describes the force that holds nucleons together is called quantum chromodynamics so I called it the colour force.

@deepthought said
In quantum field theories each field has an associated particle. A quantum of the electromagnetic field is known as a photon. For the weak force the quanta are the W and Z particles, for the colour force it is the gluon (see side note below), and similarly we expect the gravitational field to have an associated particle which is known as the graviton.

The matter fiel ...[text shortened]... force that holds nucleons together is called quantum chromodynamics so I called it the colour force.

"For the weak force the quanta are the W and Z particles"

The weak force is gravity. Nobody has discovered the quantum force of gravity that I am aware of. Are you claiming W and Z particles cause gravity?

What do you mean by an associated particle? Associated in what way?

"In the quantum field theory picture the particles are pointlike"

What is meant by "pointlike"? It is almost as if physicists are making up a bunch of jargon terms to avoid explaining anything because they don't want to admit they are confused.

What is a point? Does it have mass? If an electron has mass why is it called pointlike?

@metal-brain said

The weak force is gravity.

No, it's not.

https://en.wikipedia.org/wiki/Weak_interaction

@kazetnagorra said
No, it's not.

https://en.wikipedia.org/wiki/Weak_interaction

Arr, yes, despite what I heard to the contrary on several flawed science documentaries on TV, which is probably where ignorant MB got that from, that is correct. The flawed demonstration I have seen on TV is the TV presenter suspending a pin against gravity with a magnet. And the reason why that is flawed is explained here;


https://en.wikipedia.org/wiki/Fundamental_interaction
"...Gravitation is by far the weakest of the four interactions at the atomic scale, where electromagnetic interactions dominate. But the idea that the weakness of gravity can easily be demonstrated by suspending a pin using a simple magnet (such as a refrigerator magnet) is fundamentally flawed. The only reason the magnet is able to hold the pin against the gravitational pull of the entire Earth is due to its relative proximity. There is clearly a short distance of separation between magnet and pin where a breaking point is reached, and due to the large mass of Earth this distance is disappointingly small.

Thus gravitation is very important for macroscopic objects and over macroscopic distances ..."

This shows one of the problems with the many TV science docs aimed at laypeople ; the presenters, even if they are themselves scientists, that try to explain it to them tend to oversimplify it or, worse, sometimes get the facts simply wrong! I have sadly seen that happen a lot. It often leads to many layperson misconceptions (and I will on request give a list of a few if anyone here is interested? ). Don't know what can be done about that but I think something should be done about that.

@kazetnagorra said
No, it's not.

https://en.wikipedia.org/wiki/Weak_interaction

So there are 2 weak forces?
Gravity is often referred to as the weak force. If there are two weak forces there should be different names for them.

https://www.pbs.org/wgbh/nova/article/why-is-gravity-such-a-weakling/

@metal-brain said
So there are 2 weak forces?
Gravity is often referred to as the weak force. If there are two weak forces there should be different names for them.

https://www.pbs.org/wgbh/nova/article/why-is-gravity-such-a-weakling/

"The weak force" is short for "the weak nuclear force". Gravity is indeed weaker, but since it already has a name there ought not to be any confusion.

@deepthought said
"The weak force" is short for "the weak nuclear force". Gravity is indeed weaker, but since it already has a name there ought not to be any confusion.

What do you mean by an associated particle? Associated in what way?

"In the quantum field theory picture the particles are pointlike"

What is meant by "pointlike"? It is almost as if physicists are making up a bunch of jargon terms to avoid explaining anything because they don't want to admit they are confused.

What is a point? Does it have mass? If an electron has mass why is it called pointlike?

@metal-brain said

What is meant by "pointlike"? It is almost as if physicists are making up a bunch of jargon terms to avoid explaining anything

You don't know the meaning of the English word "pointlike" and that word is a "jargon term" that you claim physicists use "to avoid explaining anything"?

Let me help you there;

https://en.wiktionary.org/wiki/pointlike
1, Resembling a point
2, (physics) Having dimensions too small to be measured, or so small that it may be regarded as a point.

Just to further clarify; That "too small" above can sometimes, depending on context, also be "infinitely small" as in having no non-zero diameter.
Now do you understand what 'pointlike' means?
If not, which part of the above do you not understand?
Note no jargon terms are used in the above definition; just common English words.

If you really think the English words like "pointlike" are "jargon terms" then no matter what words or terms physicists use to explain something you will accuse them of using "jargon terms". We can think of a much better explanation of why you don't understand their explanations while we do.

@metal-brain said
So there are 2 weak forces?
Gravity is often referred to as the weak force. If there are two weak forces there should be different names for them.

https://www.pbs.org/wgbh/nova/article/why-is-gravity-such-a-weakling/

Gravity is a weak force. The weak force is the weak force.

@humy said
You don't know the meaning of the English word "pointlike" and that word is a "jargon term" that you claim physicists use "to avoid explaining anything"?

Let me help you there;

https://en.wiktionary.org/wiki/pointlike
1, Resembling a point
2, (physics) Having dimensions too small to be measured, or so small that it may be regarded as a point.

Just to further cla ...[text shortened]... e can think of a much better explanation of why you don't understand their explanations while we do.

"2, (physics) Having dimensions too small to be measured, or so small that it may be regarded as a point."

In other words, having no mass.

@Metal-Brain
According to BB theory, the entire mass of the universe was in a point sized volume, a LOT of mass in a very very tiny volume. So why do you think there would have to be no mass in a tiny sub atomic particle?
Could it be you just don't know what you are talking about and are flailing around like a failing student not interested in actually learning from your betters because you believe you are so superior you won't accept help from such inferior people.