Why is light massless?

[Mart]

I'd argue that the main problem of QM is its incompatability with GR.

 

Would you? What IYHO is the chief feature of this incompatibility?

[JaKiri]

Would you? What IYHO is the chief[/i'] feature of this incompatibility?

 

The quantum foam. Or fuzz. Or whatever term you wish to use.

[Zeo]

I understand that the things going on here are way out of my league, but I would like to point out that Photons actually do have mass, although it's so small it's comparable to an electron, which is proportionally 1/2000 to a proton or neutron.

[JaKiri]

I understand that the things going on here are way out of my league, but I would like to point out that Photons actually do have mass

 

We're talking about rest (or invariant) mass here using shorthand.

[Mart]

The quantum foam. Or fuzz. Or whatever term you wish to use.

 

Would that mean the assumed inherent randomness in the quantum description?

[JaKiri]

Would that mean the assumed[/i'] inherent randomness in the quantum description?

 

No, that would be the empirically evidenced inherent randomness.

[Eskay]

So, when a Photon is in motion does it emit more intense light?

[JaKiri]

So, when a Photon is in motion does it emit more intense light?

 

I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question.

[Severian]

Light is massless because it is the gauge boson of a local U(1) symmetry.

 

In other words, the universe has a symmetry, called the electro-magnetic gauge symmetry, which ensures that the photon is massless.

[Newtonian]

I'd argue that the main problem of QM is its incompatability with GR.

Rather the problems with QM are incompatible with Einsteins predictable universe.

[Mart]

Rather the problems with QM are incompatible with Einsteins predictable universe.

 

It makes me wonder what assumptions Einstein used in developing his relativity theory that made for this incompatibility. Historians of Science say Newton developed his theories using all manner of weird ideas. Einstein didn't believe that god was a gambler but what did that allow him to leave out of or put into his theory. Where is that weak link (if there is one) hiding?

[[Tycho?]]

So, when a Photon is in motion does it emit more intense light?

 

Good god.

 

Ok. A photon is light. Light is made up of photons. Light (or x-rays, radio waves, microwaves, heat, etc) is comprised of discreete packets of energy. We call these packets photons. So a photon does not emit light. It IS light. This also means that any photon always moves at the same speed in vacum- the speed of light coincidently, which is 300 000 kilometers per second.

 

Review:

Light is made up of photons.

Photons ARE light, so it can't emit light

Photons are always in motion, always moving at the speed of light ( which is the constant "c" in physics)

 

 

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

 

And dont read this post and ask another question without reading this link I give you. If you do I will flip.

[Eskay]

']

And dont read this post and ask another question without reading this link I give you. If you do I will flip.

 

Okay, thanks. I understand it now, I must have mis-heard my teacher or something- I got the idea that photons emitted light and found it confusing as you could tell. ;p

[bh_doc]

can anyone explain how a photon can have momentum when it doesnt have any mass. or is in this case momentum completely difference from the momentum we define in classical mechanics.

 

AFAIK, that's pretty much the case. (The more knowledgable here can correct me.) Classical momentum and relativistic momentum are two different, but related, beasts.