# SciContest! Why can't matter be made of photons?

Discussion in 'Physics & Math' started by BenTheMan, Aug 11, 2008.

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1. ### VkothiiBannedBanned

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But as I've noted, none of these people (scientists, researchers) said they were trying to construct a "photon-only" theory. Electromagnetism and gravity have to account for masses with charge, but photons are massless. Wikipedia has a reasonable entry on "unified field theories", which does not mention a theory constructed entirely from the interactions of massless photons.

A "photon-only" theory is a misconception, therefore, of what their theories actually were.

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3. ### camilusthe villain with x-ray glassesRegistered Senior Member

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Why can't matter be made of photons?

Because photons are massless?

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5. ### VernRegistered Senior Member

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It seems to me if I recall that an equation for mass is M = hv / cc . The only thing in the equation that is not a constant is v, which is the rate of change of electric and magnetic forces. So we could say that mass is the rate of change of electromagnetic forces. Which comes down to a definition of mass. Mass is electromagnetic change.

Photons are electromagnetic change. Photons are mass

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That is the way a photon-only advocate might descirbe mass.

Last edited: Sep 14, 2008

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7. ### prometheusviva voce!Moderator

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This is a fallacy perpetuated by overzealous popularisers of SR. Photons cannot have a mass for the following reason - their invariant mass (or if you really insist, rest mass) is zero, so they must travel at the speed of light. In SR one cannot have a frame where light is at rest, and to get your equation for the mass of the photon you have (incorrectly) combined Planck's quantum hypothesis $E = h \nu$, and the Einstein equation $E = mc^2$

What you haven't grasped is that $E = mc^2$ is only valid for massive particles at rest, and as a photon can't be at rest, it cannot be applied to to photon.

Relativistic mass is not a good concept in SR because it makes the theory mathematically inconsistent.

8. ### Magneto_1Super PrincipiaRegistered Senior Member

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photons have inertia

A photon does not have rest mass and energy. A photon has inertia and the inertia is equivalent to mass which is equivalent to energy.

Photons that are bound to a circumference, plane, or sphere are what is known as matter (atoms, and sub atomic units electrons, protons, neutrons, etc...)
e = mc^2

Photons that are not bound and are free have mass and energy in the form of inertia.
e = mc^2

Arthur Compton's experiment proved that photons and electrons interact via collisions.

9. ### gluonBannedBanned

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So who won? I would vote Vern, considering Ben was finally corrected that photons can make matter.

10. ### gluonBannedBanned

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No one disputes this. In fact, a photon can flux to matter, under a special consideration of perhaps Higgs Bosons. Then again, there may be a totally different mechanism. The fact here is that, whether photons are massless or not, should not be a good enough reason we can create two particles of gamma energy from the collision of a positron and an electron.

11. ### gluonBannedBanned

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512
Photons do not have mass, as they wouold require the estranged amount of $10^{51}$ kg, which would suggest theyn are totally energetic before their transformation into mass. So, for photon to make mass, it not only requires another photon, but requires some kind of medium.

I speculate this can be possible if you add enough energy into the vacuum, where once this has been done, you can use a real electron to mediate it into matter.... just the way we do in experiements all the time.

12. ### prometheusviva voce!Moderator

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A better way to say this is "photons have no mass but they do have momentum." You can see that by looking at the formula for relativistic momentum; $p = \gamma m v$. For the photon m = 0 and $\gamma = \infty$ so the RHS is undefined.

I have no idea what you are talking about here. Photons have nothing to do with matter - they are the particles that make up radiation, not matter. You only have to look at the spin statistics theorem to see that.

This formula does not ever apply to photons because it only applies to particles at rest, and you cannot define a rest frame for a photon so it is never at rest.

No one would disagree with the fact that photons can interact with matter particles. No one with a brain anyway.

13. ### VernRegistered Senior Member

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An advocate of a photon-only universe would say that photons do not HAVE mass. Photons ARE mass as in the equation mass = hv/cc. The only thing in the equation that is not a constant is the photons quantified as v.

14. ### VernRegistered Senior Member

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This looks like BS to me.

15. ### VernRegistered Senior Member

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If you can offer insight into this I would like to hear more about it. Ben The Man recently mentioned the Fine Structure Constant. The link shows how a photon-only universe advocate might see that.

AN mentioned the dynamics of the strong nuclear interaction. Strong Dynamics might be described like that by a photon-only universe advocate.

16. ### fedr8081100101Valued Senior Member

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Photons follow space time geodesics so when passing massive objects, those that significantly warp space, the space time geodesics are curved, therefore photons follow a curved path. This path is exactly the one a photon would take if it had mass of hf/c2. This is the mechanism by which photons can behave as if they had some mass, while not haveing any. Photons do not have rest mass. Rest mass it that which we are acustomed to dealing with.

17. ### VernRegistered Senior Member

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In a photon-only universe massive objects do not warp space. You can't use one theory to dispose of another. It's like saying my theory doesn't agree with your theory so your theory is wrong. If a theory is developed enough it will contain its own means of falsification. For example a photon-only universe where mass is built by bending photons into charged patterns can not explain the existence of the neutrino. So in as much as we know neutrinos exist we can dispose of that concept.

18. ### prometheusviva voce!Moderator

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That doesn't make it wrong. It's a very well established fact of SR (and SR has been verified in experiments many times) that it is not possible to define the rest frame of a particle moving at the speed of light, like a photon for example. $E = mc^2$ is a formula that only applies to particles in their rest frame and hence, it can never be applied to photons. Simple logic.

If my post looks like BS then it is because there is something wrong with you, not the post.

19. ### VernRegistered Senior Member

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That equation was first used by Henri Poincare to describe the momentum a photon gave to a massive object. Was Poincare wrong, or what?

Last edited: Jan 9, 2009

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please allow me a moment to post a 'stupid' .......... idea for folks to think and/or work on if they like.

Use this idea to rattle in your head a bit;

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If I take 1000 atoms of oxygen isolated (vacuum) in an absolute zero (BEC) state and weigh them.

Then take 1000 atoms of hydrogen isolated (vacuum) in an absolute zero (BEC) state and weigh them.

Then, still at BEC combine them (vacuum), then add nothing but light (whole range of em spectrum)….. (no electrons, neutrons or protons are added)

Questions: will any water be in the combined specimen?

Will the combined have a greater weight than the addition of the 2 isolated specimens (at BEC)?

Remember, both sides begin at ‘no temperature’…… so the idea that a reduction is occurring from the diatomic combination, is changed in that the elevating ‘temperature’ is caused by the em, above the BEC state. So any gain and then to the reduction must be accounted for.

Which ‘physicist’ is willing to run the progression to see the answers?

the post is not to 'side' or make any claims, it is to allow each to see for themselves if they choose to do the homework, what is correct!

enjoy

21. ### prometheusviva voce!Moderator

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I seriously doubt that, and I'd like to see a reference before I believe it. Also, $mc^2$ is an energy, not a momentum so it's not possible that it describes a momentum transfer.

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23. ### prometheusviva voce!Moderator

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Your link does not say anything about Poincare discussing momentum transfer. Having done your google I haven't found a reference to that effect either.

Why bother making up nonsense?

Also your statement "when you add energy to any massive object you increase its momentum" is BS because when you add energy to something then it is possible that its internal energy increases. When you put an iron on a fire you're adding energy to it but it's not getting an extra momentum is it?

This is the first law of thermodynamics, and is a very basic notion in physics.