Question

Do photons have mass? I know they are affected by gravity so i imagine they do, but so many people like to describe them as waves so I'm a little confused. I'm not in any physics classes but i find it all very fascinating.

Answer 1

Photons do not have mass, I think that is only system where matter exist with out mass.
many times used to describe difference between matter and mass.

Answer 2

so photons don't have mass yet they are considered matter? seems a little contradictory :P if they don't have mass then why are they affected by gravity? btw I'm not trying to be difficult i simply enjoy conversation.

Answer 3

Photons are massless - that is, they have zero rest mass.

In physics, a photon is an elementary particle and the quantum of electromagnetic radiation. It is the basic unit of light (which in fact, is an electromagnetic wave).

Although, a photon have zero rest mass, it does have momentum.

In addition, photons exhibit both wave-like and particle-like properties. This is known as wave-particle duality, which is a concept of quantum mechanics.

Answer 4

I really enjoy quantum mechanics, though i don't understand ANY of the math the theory is a rush to dive into! wave-particle duality has to do with my other questions about sub-atomic particles having consciousness or not.

Answer 5

that is a very deep question...cant answer here...but take a look at this http://www.youtube.com/watch?v=Q6Gw08pwhws might answer your question.

Answer 6

I'm watching it right now, i can already see that this guy is a great instructor. he knows how to explain complex systems in a very basic manner. great stuff, thank you!

Answer 7

Under the Newtonian laws, light would not be effected by gravity because as you know it doesn't have mass. However in general relativity postulated by Einstein, gravity is what we see as the bending of space time, so it doesn't matter if something has mass. It is actually travelling straight in curved space. Let me know if you have any more questions.

Answer 8

It's a wide spread misconception that photons are mass less. Photons do have mass, And it has been measured experimentally, indirectly by calculating the pressure they exert on a solid surface. Think "Solar Sails". But it's more "convenient" in various calculations/formulas to think of them as mass less.

Answer 9

In fact, there are many discussions on this topic. For example:

http://www.physicsforums.com/showthread.php?t=138395