What? How can you link a paper like that and completely not understand its contents? No, they did not create matter out of light. The important thing from that paper is that the light was frozen in place while it was traveling through the material. It's a nice experiment, but has absolutely nothing whatsoever to do with photon-photon interactions and creating of particle-antiparticle pairs. The word "mass" doesn't even appear in the paper, for example. The photon energies are eV level in that paper, and photon-photon interactions require billions times more. Like, gamma rays, not visible light.

You might argue, pedantically, that while the light was trapped in the sodium in that paper, the kinetic energy of the sodium atoms increased. And due to relativity, increase the kinetic energy of something also increases its mass. Well, you would be right, and that happens every time the sun shines on something and warms it up. But when you talk about creating matter from photons, they mean making brand new particles-- that is, making even the *rest mass* portion of their energy out of the photons-- not just speeding up existing particles. And that just cannot be done with light near the visible spectrum.

There is no laser in the world that gets anywhere near close to pulsing 1 quadrillion = 10^15 times per second. That's just silly. But, femtosecond pulse length lasers (i.e. 10^-15 seconds wide) are common lab devices. They tend to pulse between 10^1-10^7 times per second. So, the summary is only off by a factor of 10^8... but I can understand his confusion.

I've heard that the mass is right on the edge of what would make the vacuum state of the universe unstable. Are there hints to possible new physics here, or any interesting speculation as to a reason why? Do any GUT models predict this careful balancing?

Not entirely accurate. It would be better to say that the contacts always focus one polarization of light so you can see things close up and the other polarization normally. Normal light has both polarizations, so only one of the two will be correctly focused, the other will be incorrectly focused, causing a diffuse blur in your field of vision (in one eye.) So, 1/2 of the light in 1/2 of your eyes will be blurry. So, 1/4 of the data your brain gets will be blurry. Maybe this isn't such a problem?

Maybe you combine it with polarizing (aka polaroid) sunglasses, so that the outside world only had the correct polarization?

Yes, a picowatt is HUGE compared to visible blackbody emission at normal temperatures. Even at room temperature (which is warmer, and therefore has *more* visible emission) the human body only emits a few photons per second. This is actually measureable, and there have been papers about (very tiny) anomalous increases in the human body's blackbody radiation from electrochemical processes. Anyway, go type "h * c / (500 nm) / (1 second)" into google, and you'll find that one photon per second in the visible is 10^-19 watts. So, this is some 6-7 orders of magnitude larger than a much bigger object's emission at a higher temperature. So, yes, claiming this is blackbody radiation is idiotic.

No, the worst case is much, much lower. The problem is that there are two different definitions of efficiency going on here. The 90-100% conversion to electricity means that 90-100% of the absorbed photons are turned into single electrons. This does *not* say that 90-100% of the energy in the original photons is converted to energy in the electrons. In fact, just as in all other solar cell devices, the photons initially create fast moving electrons, converting all of their energy. But most of that kinetic energy is lost to heat before the electrons can be extracted from the device and used to do work.

So, the take-home message is that efficiency can refer to number of converted photons, regardless of how much energy was lost to heat.

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?