[Rhea]

From the little that I understand about relativity, a photon should have mass zero. Well if it hasmass zero how doesgravityfrom ablack hole (for example)affect it. If you plug in zero for the mass of a photon into the gravity equation F=G(Mm)/R^2 you will get zero.
I am confused! someone please help.

[Tormod]

Hi Rhea!

This question is answered at Cornell University's Ask a Scientist website:

Do photons have mass? If not, then how does gravity affect light (i.e. Black holes)?
http://www.ccmr.cornell.edu/education/ask/?quid=240


Hope this is what you're looking for.

[Freethinker]

Now Tormod, You know the FAQ! No posting links without expounding!

[Rhea]

Thanks Tormod! That is what I wanted to know.