Why not try to answer the question? Do the parallel traveling very closely spaced photons attract each other or not.
Here is how that was asked with some comments and observations:
Then you seem to be clearly implying (or very clearly stating?) that two, side-by-side photons traveling initially along parallel lines spaced one nanometer apart for very long time, say from a distant star 100,000 light years way to enter my eyeball, will each make a tiny warping of local space (or in simple terms, mutually attract gravitationally) as they travel and eventually either (1) merge or (2) since they can pass thur each other * without noticeable interaction to "overshoot" and then attract each other again in an oscillation that repeatedly passes thru each other.
Is that what you intended to say?
If this is true, then a photon falling in towards a tiny black Hole, BH, I think has a gravitational blue shift, but be that as it may if an enough do that the BH could be gaining mass as rapidly as it is losing it via Hawking radiation. In fact, if that is true and the photon flux is larger and long lasting, most of the BH's mass could be photons, which if the blue shift is also true begin to have sufficient energy (or EM field temperature) to destroy any matter - I.e. conditions like nano seconds after the Big Bang before it cooled enough for mater to "condense" out of the intense energy field. That was suggested in earlier post by some one else.
* like two laser beams crossing thru each other in near perfect vacuum of deep space without scattering one each other.