Is Light Matter?

[Wowbagger]

Is there a both option? Particle/wave duality and all.

Just because something can be quantized into particles does not necessarily mean those particles are "matter".

Second of all, I've heard that the so-called "particle/wave duality" is really misconception. Photons behave like photons. But, due to limitations in how we humans can emperically measure photons, sometimes they seem to behave in manner we can best describe as "particles", and other times "waves". In reality, the photon is just always behaving like a photon, and we simply don't have a better way of describing that, yet. (at least not a way that is readily understood by non-scientists.)

 

[ponderingturtle]

It depends on your definition, but in general, yes, light is matter. All particles are matter. Yes, the photon happens to massless, but it is almost certainly not the only massless particle. There is certainly no such thing as "pure energy", energy is a property of matter. A particle can have energy, it cannot be energy. The energy contained in fields is in fact contained by force mediation particles. When it comes down to it, all matter is basically the same stuff. You can consider it as a particle, a wave, or both. What you can't do is argue that one particular thing is definitely one or the other while everything else isn't. Either photons are matter along with everything else, or photons aren't matter and neither is anything else.

This seems a very different definition of matter than what people normally think. This is everything that exists is matter.

No. A fermion is simply a particle with half-integer spin. A boson is a particle with integer spin. Arguing that only fermions are matter is arguing that, for example, hydrogen is not matter.

But it is comprised of fermions and obeys the Pauli exclusion principle to my knowledge.

 

[ponderingturtle]

What is an electron?

A fermion that obeys the pauli exclusion principle and thus matter, even if it seems to be a point particle.

 

[Slimething]

So you think that being unable to occupy the same space at the same time is not a general property of "Matter"

I had no idea photons could occupy the same space at the same time. Do you have evidence for this claim?

The real problem here is that matter is no really a definition that a physicist would use, they would specify the type of particle and such. And the generally is based on that especially theoretical physicists can come up with really weird definitions and I am not comfortable enough with high energy particle physics to make it an absolute statement.

This is fundamentaly a semantic issue though. You need to define what matter is before you can say if light is or is not matter.

So, it's a circular argument. I can buy that. Is there a general consensus among the physicists of the world or is this one of those things settled by beer on a case by base basis?

It does not obey the Pauli exclusion principle so you can put as many photons as you want in the same quantum state. If matter could do this think about all the storage options that that would make for you house? You could pile an infinite ammount of things in the corner!

Your definition of matter seems to be anything comprised of particles that obey Pauli. That seems pretty good. Is that the standard definition or is it something you came up with? If so, what are the contravening definitions? You're the one who wrote "generally", not me. A "generally" definition isn't all that useful when sifting either/or situations.

 

[ponderingturtle]

I had no idea photons could occupy the same space at the same time. Do you have evidence for this claim?

Link That shows what the Pauli exclusion principle is, and note that they don't mention photons as something that obeys it.

There is however a more satisfactory and fundamental distinction between light and matter, which should be understandable to you if you have had a chemistry course. In chemistry, one learns that electrons obey the Pauli exclusion principle, which forbids more than one electron from occupying the same orbital if they have the same spin. The Pauli exclusion principle is obeyed by the subatomic particles of which matter is composed, but disobeyed by the particles, called photons, of which a beam of light is made

link

So, it's a circular argument. I can buy that. Is there a general consensus among the physicists of the world or is this one of those things settled by beer on a case by base basis?

Not really it is more that is something matter or not is not really an issue, what kind of particles it is and how they interact is much more the issue. So matter is much more a lay term, and as such is not very precisely defined.

As a different case in point there is no such thing as a antiphoton, while there are antiprotons and anti electrons(and a great many other particles as well)

Your definition of matter seems to be anything comprised of particles that obey Pauli. That seems pretty good. Is that the standard definition or is it something you came up with? If so, what are the contravening definitions? You're the one who wrote "generally", not me. A "generally" definition isn't all that useful when sifting either/or situations.

I am not sure that there is a standard definition, as I said when studying physics it was not a term that I remember seeing a real definition of.

 

[Southwind17]

It does not obey the Pauli exclusion principle so you can put as many photons as you want in the same quantum state. If matter could do this think about all the storage options that that would make for you house? You could pile an infinite ammount of things in the corner!

My three kids seem to be quite adept at this. Does that answer the question?!

 

[Cuddles]

But it is comprised of fermions and obeys the Pauli exclusion principle to my knowledge.

OK then, helium.

I had no idea photons could occupy the same space at the same time. Do you have evidence for this claim?

They can.

So, it's a circular argument. I can buy that. Is there a general consensus among the physicists of the world or is this one of those things settled by beer on a case by base basis?

Your definition of matter seems to be anything comprised of particles that obey Pauli. That seems pretty good. Is that the standard definition or is it something you came up with? If so, what are the contravening definitions? You're the one who wrote "generally", not me. A "generally" definition isn't all that useful when sifting either/or situations.

I'm with the beer argument. Defining matter is a bit like defining life. No-one quite agrees exactly what it is and no-one can manage to come up with a coherent definition that fits their own ideas without having various glaring exceptions.

I've never really thought about it before, but it does seem that my view is that everything is matter. To be honest, I don't see anything wrong with this as a defintion. Everything is either matter or is a property of matter. It doesn't really seem to add anything to understanding if you define some things as not being matter, so there doesn't seem any good reason to do so. However, since matter is never used as a technical term, it doesn't really matter how you define it. Again, much like life.

As a different case in point there is no such thing as a antiphoton, while there are antiprotons and anti electrons(and a great many other particles as well)

Technically, photons are their own anti-particles.

I am not sure that there is a standard definition, as I said when studying physics it was not a term that I remember seeing a real definition of.

As I say above, now I think about it I don't really think there is a standard definition, nor any real need for one.

 

[Jimbo07]

But it is comprised of fermions and obeys the Pauli exclusion principle to my knowledge.

Not all bosons are necessarily divisible (think Higgs). PEP doesn't apply. Bose-Einstein condensates are experimentally possible.

...

Actually, I'm intrigued by the idea that there doesn't seem to be a formal, technical definition of matter. Come to think of it, I don't remember many professors using the word!

 

[ponderingturtle]

Not all bosons are necessarily divisible (think Higgs). PEP doesn't apply. Bose-Einstein condensates are experimentally possible.

I might be a bit fuzzy on the exact effects of bose-einstein condensates, but I do not remember them being able to take up less space in a fundamental fashion, just that the boundries between the particles become less distinct.

Actually, I'm intrigued by the idea that there doesn't seem to be a formal, technical definition of matter. Come to think of it, I don't remember many professors using the word!

Well matter is easy to define on a macroscopic scale, it is when you get into microscopic scale with odd particles that things get confusing.

Then again a macroscopic definition of matter is not that useful, and not at issue in this thread.

 

[ponderingturtle]

OK then, helium.

Well maybe, I take it you are referring to super fluid effects?

Technically, photons are their own anti-particles.

That I don't like because they do not annihilate releasing their energy as proper anti particles do. They totally cancel each other out. In some ways similar but in other very different.

As I say above, now I think about it I don't really think there is a standard definition, nor any real need for one.

Not on a real formal level.

I am comfortable with matter is that which is comprised of fermions, as even helium and such might be a boson in aggregate but its constituent particles are fermions.

 

[Jimbo07]

I am comfortable with matter is that which is comprised of fermions, as even helium and such might be a boson in aggregate but its constituent particles are fermions.

I also like the idea that "matter" is only relevant above atomic scales. That is, matter is comprised of elementary particles, NOT that elementary particles are matter.



ETA: isn't the fermionic matter idea pretty much invalidated by indivisible bosons?

 

[ponderingturtle]

I also like the idea that "matter" is only relevant above atomic scales. That is, matter is comprised of elementary particles, NOT that elementary particles are matter.



ETA: isn't the fermionic matter idea pretty much invalidated by indivisible bosons?

The one cited was I beleive the Higgs, and then is that matter, and does it exist(as I do not think it has been observed)

 

[Jimbo07]

The one cited was I beleive the Higgs, and then is that matter, and does it exist(as I do not think it has been observed)

I don't know the answers to these things. I think saying Higgs is (or isn't) matter is subject to the same problems brought up in this thread. It has yet to be observed, but may...

...meh...

BTW, I've been somewhat imprecise in my language. Individual quarks don't tend to exist separate from protons, so is a proton indivisible? This isn't what I meant. Someone would have to provide an example of a boson that does not have constituent fermions.

I probably don't know enough to have waded into this, so I guess I'm back to my original post:

what impact does my opinion on the relationship of light to a definition of matter have to do with anything? How can it be a poll?

Thanks for voting. I’ve been debating this question in another thread and wanted to find out what other forum members think.

What does it matter what other forum members think? Linky?

 

[ponderingturtle]

I don't know the answers to these things. I think saying Higgs is (or isn't) matter is subject to the same problems brought up in this thread. It has yet to be observed, but may...

...meh...

BTW, I've been somewhat imprecise in my language. Individual quarks don't tend to exist separate from protons, so is a proton indivisible? This isn't what I meant. Someone would have to provide an example of a boson that does not have constituent fermions.

Individual quarks can't exist by themselves. The strong force is too strong it will not allow color charge to exist unbound to anything.

what impact does my opinion on the relationship of light to a definition of matter have to do with anything? How can it be a poll?

A poll might be a bad way of determining the properties of light, but it might be a good way of settleing the definition of a word like matter.

 

[Cuddles]

I might be a bit fuzzy on the exact effects of bose-einstein condensates, but I do not remember them being able to take up less space in a fundamental fashion, just that the boundries between the particles become less distinct.

They really do take up less space, the particles exist in exactly the same state as each other, including position.

Well maybe, I take it you are referring to super fluid effects?

No, helium can form a Bose-Einstein condensate. I'm fairly sure hydrogen could as well, but as far as I know that has never been done experimentally, mainly because helium is so much easier to work with.

That I don't like because they do not annihilate releasing their energy as proper anti particles do. They totally cancel each other out. In some ways similar but in other very different.

Not always, they can result in pair production just like any other particle-anitparticle interaction. In fact, deconstructive interference isn't really cancelling out at all. They seem to cancel locally, but if you have two photons traveling in opposite directions, they can interfere where they overlap but then carry on traveling as if it had never happened. Photons are also not the only particles which act as their own anti-particles.

The one cited was I beleive the Higgs, and then is that matter, and does it exist(as I do not think it has been observed)

All force carriers so far known are bosons. They are all indivisible. In fact, calling it the Higgs boson is a bit premature. Since it hasn't been observed we can't say for sure that it would be a boson, although that is what theory predicts. The more accurate term is simply the Higgs particle.

 

[ponderingturtle]

They really do take up less space, the particles exist in exactly the same state as each other, including position.

Fully in the same quantum state? Hmm must read up more on BEC's

Not always, they can result in pair production just like any other particle-anitparticle interaction. In fact, deconstructive interference isn't really cancelling out at all. They seem to cancel locally, but if you have two photons traveling in opposite directions, they can interfere where they overlap but then carry on traveling as if it had never happened. Photons are also not the only particles which act as their own anti-particles.

But pair production is not from two photons interacting, but one photon interacting with say an electron and turning into an electron and an antielectron(yes I know positron is the word, but antielectron shows that it is an antiparticle better)

Pair production is not caused by two photons annihilating each other, at least to my knowledge.

All force carriers so far known are bosons. They are all indivisible. In fact, calling it the Higgs boson is a bit premature. Since it hasn't been observed we can't say for sure that it would be a boson, although that is what theory predicts. The more accurate term is simply the Higgs particle.

but why should it be considered matter? Is it supposed to have mass?

I might not have the best physics background here not having any graduate effects and no real particle physics background.

 

[Dancing David]

So you think that being unable to occupy the same space at the same time is not a general property of "Matter"

Especialy when you consider Bose-Einstien Condensate. Where matter does occupy the same space.

 

[Dancing David]

A fermion that obeys the pauli exclusion principle and thus matter, even if it seems to be a point particle.

Except in the Bose-Einstien Condensate. I do get your meaning and it is one of the characteristics associated with 'matter', however electrons also take quantum jumps and do the tunneling thing.

 

[Dancing David]

I don't know the answers to these things. I think saying Higgs is (or isn't) matter is subject to the same problems brought up in this thread. It has yet to be observed, but may...

...meh...

BTW, I've been somewhat imprecise in my language. Individual quarks don't tend to exist separate from protons, so is a proton indivisible? This isn't what I meant. Someone would have to provide an example of a boson that does not have constituent fermions.

Not sure on the spin of quaks, I would have to look, neutrons are also made up of three quaks (theoreticaly) and mesons are quaks pairs.

I think I could be very wrong.

 

[Yllanes]

Not sure on the spin of quaks, I would have to look, neutrons are also made up of three quaks (theoreticaly)

Quarks are fermions with spin 1/2.

and mesons are quaks pairs.

I think I could be very wrong.

You are right, mesons are a quark-antiquark pair.