You can derive the Schwartzchild radius using newtonian physics like clone53421 is claiming, and if that was what people were basing the existence of black holes on, then clone would be right. But it is just an accident that this derivation works.

If you do the derivation properly, using general relativity, you get the same result for the Schwartzchild radius. Though there are some interesting differences in how "radius" is defined in general relativity.

So, I'm sorry that the only derivation you saw was the incorrect classical physics one (which is used to motivate the result using simple math), but the answer is still true. But honestly, if you really thought that you were the first person to realize this problem with the derivation-- that none of the thousands of physicists to learn it since it was derived had noticed this glaringly obvious problem, then you are a monumental fool.

Metamaterials don't need to be periodic. They are made up of small (compared to the wavelength of light they work with) nano-fabricated structures, but even if they are randomly distributed it will have the desired effect. Just like both periodic structures (crystals) and amorphous ones (glass) have "normal" dielectric constants, so can metamaterials.

Some people say "periodic" when they just mean "made up of small stuff". If that was your complaint, then I challenge you to find something with any index of refraction that isn't "made up of small stuff."

Assuming you weren't being snarky, he's just speaking in the language of physics. Don't take "observe" literally-- he just meant when the light reaches us. If you were being snarky, then when you close your eyes, you'd be likely to be eaten by a grue.

Yes, but that's meaningless, and moreover you don't have to speculate. If the light has not reached us yet, then the two events (here&now and the ka-boom) are not causally connected. That is, they are "space-like" separated. You can show that there exists a reference frame with any time duration between two space-like separated events. So, in some reference frame, I'm typing this post *after* the light from the supernova has occurred. In another frame, I'd have to wait a billion years for it to happen. And all choices are equally arbitrary, including yours.

Perhaps it would help if I logged in... we can all be glad that ACs cannot mod things up.

No, he would never say the last line. Time travels at the speed of light. When we see it, it is the same instant of time when it exploded. Or more formally, the two events become causally connected the instant we see the light.

Experimental data speculation + crackpot plasma theory = Slashdot science?

Don't read too much into that sentence. They're just saying that if they found a clump without stars inside it, then one can immediately rule out a star-based source of gamma radiation.

If they don't rule that out, then it will be hard to argue that the gamma rays are from dark matter, and not some other more mundane source.