One law down, two to go? iRobot, manufacturer of the Roomba vacuum, has teamed up with Taser to arm its Packbot robots with stun guns. But its hard to say whether this is actually a violation of the first of science fiction author Isaac Asimovs Three Laws of Robotics: A robot may not injure a human being or, through inaction, allow a human being to come to harm. Clearly, arming a robot with a stun gun is the first step towards breaking that rule. But the Packbots, currently used as bomb inspectors in Iraq, are remote-controlled. If theres a human operator standing at a distance with his finger on the Taser trigger, is it really the robot thats doing the harm? Yeah, probably. But please discuss.—Gregory Mone

Only tachyons can save us now!

Note to the Reader: For those of you who haven't seen Fantastic Four:
Rise of the Silver Surfer, yet are serious enough about it that you
want even the most trivial plot details kept secret until you actually
watch the movie, what follows will be a bit of a spoiler. (A rough
calculation makes us think there are about three of you out there.)
For the rest of you, don't worry, this little detail won't ruin
anything.

So, Reed Richards, aka Mr. Fantastic, is sitting in his lab trying to
think of a way to separate an alien from his cosmic surfboard when he
gets an idea. "A tachyon burst!" he exclaims.

Fast-forward a few scenes. A series of devices capable of delivering
said burst are built, one is activated, and the aforementioned alien,
known as the Silver Surfer, is cleanly knocked from his board.

Now, would this really work? Tachyons are theoretical particles
believed to travel faster than the speed of light. Trying to think
about what effect they would have on a liquid-silver alien can be
thoroughly mind-bending—would they send him back in time or even
arrive at their target in the past, thus having no effect whatsoever?
So, we appealed to University of Washington physicist and science
fiction author John G. Cramer, who has the scientific and imaginative
chops to handle such questions.

First, Cramer notes that knocking the surfer off his board would
require a transfer of momentum. And while the momentum of the
hypothetical tachyon beam would be relatively small, there might be
another, more dramatic effect. "The delivery of energy would be much
more efficient than the delivery of momentum," Cramer says, "so it
seems more likely they would blow the Silver Surfer apart rather than
knock him around."

Instead, Cramer proposed another, decidedly less-sexy idea. "I think a
cannonball or an artillery shell would work a lot better."

So, Mr. Fantastic, next time you try to save the world, do it the
old-fashioned way.—Gregory Mone

The Cosmos 1 solar sail experiment was lost on Tuesday when the Russian Volna rocket carrying it to orbit failed, according to the Russian Space Agency. Had the launch been successful, the experiment would have tested whether sunlight could have pushed the spacecraft into a higher orbit. Explore the mission that was to be with our exclusive slideshow, pulled from the pages of Popular Science.

On June 21, the California-based nonprofit Planetary Society will attempt for the fourth time to launch its privately funded Cosmos 1 solar sail.