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Mission not-so-impossible

NBC News
Click for video: How impossible
is teleportation? Physicist Michio
Kaku gives his perspective.

Just how impossible are such science-fiction concepts as teleportation and invisibility? They're not that impossible, physicist Michio Kaku says in a new book titled "Physics of the Impossible." In fact, they're considered mere Class I impossibilities - and someday soon they may be off the impossible list altogether.

Now, if you're looking for a Class III impossibility, there are only a few things in Kaku's book that rise to that level. See if you agree with his assessment.

"Many times, physicists say that certain things are impossible – like physicists said that airplanes were impossible at one point," Kaku told me. "That's because we didn't understand the laws of physics very well. Well, today we have a pretty good handle on Einstein's relativity theory and quantum theory. And now we have to expand our horizons as to what is really impossible."

To some extent, it depends on what your definition of the word "impossible" is. For decades, scientists (and science-fiction authors) have talked about Type I, Type II and Type III civilizations - that is, civilizations that can harness the power of an entire planet (Type I), a star (Type II) or a whole galaxy (Type III). On this scale, we rate as a Type 0 civilization.

Kaku picks up on this idea in his classification system for impossibilities:

  • A Class I impossibility is something that doesn't violate the known laws of physics, and could conceivably become possible decades or a century from now. Back in 1800, airplanes might have been on that list, just as "Star Trek"-style cloaking devices are today.
  • Class II is reserved for technologies that sit on the very edge of our understanding of physics, and might be realized thousands or millions of years in the future. Faster-than-light spaceships, wormholes and backward time travel are on Kaku's Class II list.
  • Class III impossibilities are feats that clearly violate the known laws of physics. "If they do turn out to be possible, they would represent a fundamental shift in our understanding of physics," Kaku said. Buillding perpetual motion machines and predicting the future are the two broad topics that get a Class III rating in Kaku's book. (But if you can go back into the past, couldn't you in effect predict or change the future? Well, maybe not.)

Kaku has always been one to give wide latitude to scientific possibilities, in a series of books including "Hyperspace" and "Visions." He told me he wrote this latest book because some of the things that were once thought to be purely science fiction are starting to look as if they're possible, at least in the realm of lab experiments if not practical applications.

"Things that a physicist would snicker at today could become possible in the coming decades," he said. "As we get a better grasp on quantum theory, we think that it may be possible to make objects invisible. It may be possible to teleport them like you see on 'Star Trek.'  So some of the things that we see in science fiction could very well become science fact in the coming years."

Turning the impossible into the possible usually comes with caveats:

The reality behind achieving the impossible may not always be worth the trouble. For example, take psychokinesis, the ability to move things with your mind. Kaku classifies this as a Class I impossibility - because soon scientists could conceivably set up a system that reads your thoughts using a brain-imaging device, processes your mental command using a computer, and then levitates objects magnetically using room-temperature superconductors.

All that sounds a lot clunkier than using Uri Geller's spoon-bending trick - or just walking over and picking up the darn spoon yourself.

Speaking of Uri Geller, Kaku notes in the book that scientists aren't always good at picking up on hoaxes that seem to achieve the impossible. "Scientists are trained to believe what they see in the lab. Magicians claiming psychic powers, however, are trained to deceive others by fooling their visual senses," Kaku writes.

On the other hand, scientists (and, by the way, journalists who write about scientists) aren't always good at picking up on what is truly possible. Kaku's reference to magicians brings science-fiction guru Arthur C. Clarke's three laws of impossibility to mind: 

  • "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
  • "The only way of discovering the limits of the possible is to venture a little way past them into the impossible."
  • "Any sufficiently advanced technology is indistinguishable from magic."  

At age 61, Kaku is hardly elderly. But is he right or wrong about scientific impossibilities? Take this quiz to find out whether you agree or disagree with Kaku's classifications, and feel free to weigh in with your own opinion below.