A Working Photon

[foodchain]

Not to say the universe is some giant ice cube always trying to melt away, but what all is matter. Basic definition has it as anything that occupies space and has mass, so does that exclude photons then? See I am trying to make some hypothetical assumptions about things, like if you can view physical processes as transformations involving stuff in the categories of matter and energy. Basic definitions of energy has that it’s the ability of a system to do work, or work done by a system in short, but the photon is just work then?

 

 

I know it’s the confusion of dealing with words, but it’s the physics definition of matter that excludes photons from being in that category I think. So is a photon matter, and by what definition is or isn’t it?

Edited June 1, 2009 by foodchain
Made post shorter, added some clarity.

[timo]

1) The particle physicists definition: Standard Model elementary fermions and bound states containing Standard Model elementary fermions. Since the photon is a Standard Model elementary boson, it is not matter.

 

2) Cosmo-guys definition (afaik): Stuff that is well-treatened as massless is radiation, stuff with significant mass (compared to thermal energies I'd think) is matter. Since for massless photons, being massless is a good approximation, photons are not matter in the cosmo sense.

 

3) Definition of people who don't understand that "mass" and "matter" are two different words (even if they start with the same letter): A photon has energy, therefore by the only thing that I know of this Einstein guy (E=mc²) it is matter. In that definition it counts as matter.

 

1) Is probably closest to what you'd call a definition that everyone (in physics) agrees on - although mainly because there's not so much variety of elementary particles on a larger scale; it's all just quark-gluon combinations, electrons or photons there. 2) Is just a practical definition for calculations but I do not know how widespread it really is (I just happen to have read it in a cosmo book), 3) is probably the most widespread definition on the internet ...

 

The idea that a photon was only energy is widespread and silly. A neutron has mass and energy. A photon has energy but no mass. A car has a color and tires. A ship has color but no tires. No one would call a ship being a form of color. But for a photon people suddenly think it was a sensible idea calling it "pure energy" or similarly.

[mooeypoo]

Off topic discussion was moved to the Pseudoscience/Speculation forum.

 

Please keep this on topic.