As I understand it, although a photon has no rest mass, it does have a gravitational field that is a function of the energy (frequency) of that photon.

Is there a frequency above which a single photon's gravitational field results in a black hole? Or could there exist a high enough concentration of energetic photons that together create a black hole? Would this black hole still travel at the speed of light?

The reference to an anti matter BH presumably refers to one that has formed by the collapse of an massive anti matter star, after the BH has formed is it possible to determine whether the original star was matter or anti matter ?

...two black holes that are identical except that one was formed from matter, and the other from antimatter...

If such a frequency did exist then it'd be possible to change to a frame of reference where the energy/frequency is too small and therefore no black hole exists in that frame. The existence of a black hole is invariant so it follows that the answer to your question is no.

The following is my understanding of the related physics: Although a single photon has zero mass and thus no zero momentum frame, the same can't be said for two photons moving in opposite directions. The invariant mass of the two photons is non-zero and there is a frame of reference in which the total momentum is zero. If, in this frame, two photons of sufficient energy "collide" they will form a black hole.

So, in this case, with two (or n pairs of) photons traveling in opposite directions, no frame of reference will result in a lower observed aggregate energy?

If, in this frame, two photons of sufficient energy "collide" they will form a black hole.

Quote from: PmbPhy on 11/06/2015 17:57:21 If, in this frame, two photons of sufficient energy "collide" they will form a black hole.It also depends on how large are the photons and I have no idea of that.--lightarrow

Quote from: lightarrow on 13/06/2015 18:35:35Quote from: PmbPhy on 11/06/2015 17:57:21 If, in this frame, two photons of sufficient energy "collide" they will form a black hole.It also depends on how large are the photons and I have no idea of that.--lightarrowPhotons are point particles. However the probability of where they are is not a point function.

If photons really were Point particles, the Energy density would be very high and two opposite (common) beams of light should easily have the possibility to form Black holes.

But, another reason that the electron is not considered a black hole, even assuming that its radius is infinitely small, is that it obeys the laws of quantum field theory. Normally, when one speaks about black holes, one is talking about them in terms of Einstein's theory of general relativity. No one is sure how nature merges Einstein's theory with quantum field theory. So we aren't really sure if the idea of a black hole makes sense on distance scales as small as the (possible) radius of the electron.. Our best idea to unify general relativity with quantum field theory is an idea called string theory, but string theory still appears to be a long way from being put to any experimental tests.

Quote from: lightarrowIf photons really were Point particles, the Energy density would be very high and two opposite (common) beams of light should easily have the possibility to form Black holes. That's a classical argument which you're trying to use in quantum mechanics so it's invalid argument.

Electrons, photons etc. behave the laws of quantum field theory. Seehttp://www.physlink.com/Education/AskExperts/ae191.cfmQuoteBut, another reason that the electron is not considered a black hole, even assuming that its radius is infinitely small, is that it obeys the laws of quantum field theory. Normally, when one speaks about black holes, one is talking about them in terms of Einstein's theory of general relativity. No one is sure how nature merges Einstein's theory with quantum field theory. So we aren't really sure if the idea of a black hole makes sense on distance scales as small as the (possible) radius of the electron.. Our best idea to unify general relativity with quantum field theory is an idea called string theory, but string theory still appears to be a long way from being put to any experimental tests.If I were you I'd ignore the second response. I consider it to be quite flawed.

The probability of finding a photon in a particular place is related to its wavelength.

The wavelength of light gets smaller as the energy gets higher.When the energy gets high enough to form a black hole,