What about aliens that resemble us, like the Vulcans, Klingons and Romulans, along with virtually every other race on Star Trek?
While the likelihood that there isn't life elsewhere is extremely small, the likelihood that extraterrestrial life resembles life on Earth is probably not great either, in my opinion.

As for dealing with potentially hostile aliens, what exactly are phasers?
Phasers are like lasers, really—they are directed-energy weapons.

Could they exist someday?
I just got one on my iPhone. You can go online and download a phaser app because of the new movie. I thought I'd better have it.

But the problem with a real phaser is that it would be pretty hard to generate the energy to heat something or someone up to a billion degrees to vaporize them. You would get some recoil, too.

What about space ordinance—that is, photon torpedoes?
Well, I could never understand the name, because photon torpedoes are antimatter weapons. You get the biggest bang for your buck that way—you never get more energy than you do when you annihilate matter with antimatter. That's why the warp drive is matter–antimatter-powered, as well. Of course, it's hard to create antimatter, much less carry it around. It takes a tremendous amount of energy to produce antimatter. If we used the antimatter-making device at Fermilab just outside Chicago, the energy cost would be many thousands of times the gross national product of the U.S. to produce enough antimatter to light up a lightbulb. As for storing antimatter, you need huge magnetic fields to keep it away from touching container walls made of matter. Given the infrastructure required to keep antimatter around, it might be more effective ounce-for-ounce to just carry around hydrogen bombs.

What about when the space weaponry is aimed at you?
The shields in Star Trek work by bending space like gravity, so objects get carried away with space as it gets bent around the ship. Sounds great, of course, but as I say in my book, the sun, which is a million times the mass of Earth, bends light around it by less than a thousandth of a degree. So it's very hard to imagine the gravitational energy that would be needed to swerve something 90 degrees. I think the only kind of shields that are feasible are those that would destroy the incoming object before it hits you, rather than diverting it.

On to, "Beam me up." How plausible are transporters?
As I discovered pretty quickly, I would not make a transporter the way the Star Trek writers do. First you decompose somebody into a matter stream, although taking a person apart at the atomic level would require heating them up to a few billion degrees. Then you turn them into energy. However, the energy equivalent of an average human being is something like a 1,000-megaton nuclear weapon, so that's not environmentally friendly either.

So I would do what I do when I surf the Internet—I'd move the bits. I'd scan you and try to get all the information, the bits, which make you a human being. But that's a hell of a lot of information. From Earth, you'd have to stack 100-gigabyte hard drives a third of the way to the center of the Milky Way or so to hold it all. And at current information transfer rates, it would take longer than the age of the universe to transmit that much data. But the key obstacle is still the Heisenberg uncertainty principle, which says I can't scan you and measure you at the atomic level to make an exact replica of you, much less actually put you together in a remote place with atomic resolution. [As Krauss points out in his book, the Star Trek writers get around this physical showstopper by outfitting transporters with "Heisenberg compensators".—Editor's note]