What is the actual size of a photon?

[dmtr]

E = mc^2 is not valid for a photon...

E^2 = (mc^2)^2 + (pc)^2

or did you mean that m = m_0 x Gamma ?

then Gamma = infinity for photons...

sorry dmtr, there is something strange going on here :(

and what is a CS grad?

Computer science graduate. Read "complete failure in physics".

Yes. E^2 = (mc^2)^2 + (pc)^2. But m = 0. So E = pc.
Now I'm trying to calculate the equivalent increase of the mass of the black hole (assuming I throw that photon into it), AFAIK I can use the mass-energy equivalence principle - E = mc^2 for that.

 

[ZapperZ]

The OP appeared to have not participated in this thread beyond the first post. As has been pointed out, this has been discussed already many times before, and a link to one of them has been provided.

How this thread has somehow meandered into a black hole is beyond me.

Zz.