I have no idea whether we can create an AI, but let's suppose we can, and that we can create one that's more intelligent than a person. What do we do if it suddenly decided it wanted to go Ultron on us? Just pull the damn plug!

My guess is a nascent AI will live inside a giant supercomputer cluster somewhere, and will probably run on electricity. Which means that if its consciousness was interrupted by a power loss for even a microsecond, just like your regular computer will crash, an AI so deprived will die. It's possible an AI might be more robust than a biological mind, but I wouldn't count on it; deprive neurons of oxygen for but a few minutes and they're doomed. A superpowerful AI would presumably be a much more complicated thing than a computer OS, and my guess is it would react just as well to a power interruption as any desktop would if the power were disrupted.

Literally the only way an AI could destroy or seriously harm humanity is if it were hooked up to the world's power grid, or directly controlled nuclear reactors or nuclear missile launch codes. Yeah if we do something that stupid (looking at you Terminator 3) then it could destroy us. But heck, even a regular computer system that was so connected could wipe us out if it crashed or malfunctioned or was hacked.

So morale of the story? Let's deep-six the Internet of All Things while we still can. AI guys, knock yourself out and build the next Skynet - just make sure to surround it with an airgap. To the DoD, PG&E, et al, I say don't even think about hooking everything up to a single network!

IANAP, but from what I read in most models of inflation there should be primordial gravitational waves, which could be indirectly detected based on the polarization of the CMB (b-modes). These waves (if they exist) would go all the way back to the inflationary period itself.

The BICEP2 experiment was designed to look for these, and last year announced detecting b-modes in the CMB. Of course, as we now know thanks to Planck their discovery is probably due to dust polarization. Are there any current or planned experiments that could differentiate between dust polarization and potential gravitationally-caused polarization?

More like sandtrout. "My skin is not my own." - Leto II, Children of Dune

Right?!

Sadly this is the only Harry Harrison novel I've read, but I still remember it vividly. It's one of the better alien invasion stories with a thoughtful twist at the end. Also, I vividly remember some of the illustrations - creepy aliens!

I thought that the fine-structure constant was dimensionless, so it always has a value of approxmiately 1/137. Does that mean in natural units (h=c=G=1), e must be the square root of 1/137?

From what I've read, there's nothing wrong with the results of the Miller-Urey experiment, only whether its setup was actually similar to conditions on the early Earth. In other words, it is unlikely that Earth's original atmosphere had large amounts of methane, ammonia and hydrogen (e.g. a Jupiter-like atmosphere). More likely it consisted of elemental nitrogen (N2), carbon dioxide, and water vapor. Using a mixture like that, very few organic compounds can be created by electrical discharges.