Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Does a thermal photon radiate spherically whereas a photon radiates in a circle/beam? How do you tell a thermal photon of, say 3 eV, from a photon of light?

share|improve this question
    
@John Rennie, Now, if I got it right, visible light is just thermal radiation.Since it has roughly 4000°K, it is correct to say that if we concentrate enough photons we can melt down any metal? –  bobie Aug 5 at 9:37
1  
Yes, bobie, that's correct. Google "solar furnace" for more information. Some can reach temperatures up to 3500°C. –  Nate Kerkhofs Aug 5 at 12:10

1 Answer 1

up vote 7 down vote accepted

All photons are excitations of the photon quantum field. The photon is actually not a great description of propagating light - it tends to be far more useful when you're considering light exchanging energy with something else.

If you insist on a photon description then you'd have to treat the radiation as a superposition of photons. A beam of light would be a superposition of photons moving in roughly the same direction, while spherical radiation would be a superposition of photons moving in all directions.

Whatever the case, all photons are excitations of the same quantum field irrespective of their source, so the simple answer to your question is no.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.