Injectable nanogel can monitor blood-sugar levels and secrete insulin when needed.
Trekkers who have trouble separating science fact from fiction got a dose of reality last week when physicist Lawrence Krauss laid down the laws -- Newton's laws -- and explained how writers of the Star Trek TV series had managed to subvert them.
No human being could survive the USS Enterprise's quick acceleration from standstill to the speed of light, explained the author of The Physics of Star Trek (HarperCollins, 1995). The forces would turn any starship passenger into "chunky salsa... Every time Jean-Luc Picard says 'Engage,' he's committing suicide," said Dr. Krauss, an MIT alumnus (PhD 1982).
Speaking to a near-capacity audience in Wong Auditorium, Professor Krauss, chair of the physics department at Case Western Reserve University, said he was pleased that no one showed up in uniform. "I have lectured when there were more Klingons than humans in the audience," he said.
The average person cannot comfortably bear more than three Gs, a pressure similar to that of three people sitting on your chest, he said. Keeping the force that low would mean accelerating so slowly (by Star Trek standards) that it would take about two and a half months just to reach half the speed of light, making even a short intragalactic trip prohibitively long for a one-hour episode.
To solve this dilemma, the Star Trek writers came up with -- but have yet to explain -- "inertial dampers," miraculous devices that somehow invalidate Newton's laws of motion aboard the Enterprise. When the inertial dampers get knocked out of commission, said Professor Krauss, you see the crew thrown around the bridge in that special starship stumble familiar to any fan of the popular TV show created by Gene Roddenberry.
While the Star Trek universe operates much like our own in theory, the writers take a few laws of relativity to impossible extremes, mathematically speaking. Professor Krauss ran through some of the most significant Star Trek phenomena to show what the show's writers get right -- holding to the possible, if not the actual -- and where they err completely. But, he reminded the audience, we're dealing with "what is possible, not what's practical."
Assuming humans could find a way to travel at the speed of light and explore the galaxy more fully, a trip across the Milky Way (spanning 100,000 light years) would still seem to be 100,000 years in duration to the people back home, but would take less time for the travelers because clocks slow down at or near light speed. "That's a science fact," said Dr. Krauss.
If the Enterprise went on a 10-year mission (in crew time) traveling at light speed, Federation officials would have to wait 25,000 years for its return. This could mean that one week into the trip, Captain Picard would find it impossible to file a report with his home-base commander. She may have retired during the years since he left.
To solve this problem, the Federation set a speed limit for normal travel at one-quarter light speed. That keeps everybody's clocks nearly synchronized. Paradoxically, this would hold Federation starships to a crawl. They'd never make it to distant points controlled by the Federation.
Enter starship warp drive, which warps spacetime so that it actually expands behind the spacecraft and contracts ahead, dramatically and quickly changing the ship's location by creating shortcuts between distant places.
It's not impossible, said Professor Krauss. But it would require exotic (negative) matter in quantities that we've never seen. To produce the gravitational field needed to warp spacetime would also require more energy than our Sun will produce in its lifetime.
The same would be true of wormholes -- tunnels between two points of curved spacetime. A stable wormhole would require huge amounts of lasting, negative energy. Dr. Krauss can't say whether this is impossible. Scientists' present-day knowledge of negative energy shows it to exist only briefly in very small quantities.
The light projections used to create fantasy worlds in the Enterprise's computerized holographic recreation room are possible according to the laws of physics, but would be limited today by computer memory size. A more fundamental problem with getting the holodeck to work "is matter," Dr. Krauss said. There's no way to make an image of light solid. "Eventually you'll hit the wall if you walk around" in your holodeck image.
Professor Krauss predicted that in less than 200 years, we'll have computers with enough memory to store information about every atom in a person, transfer that information, download it and use it to recreate the person somewhere else. (Unless you wanted to have two of the same person, the original being would need to be vaporized, which would take the energy equivalent of a megaton of nuclear weapons, he said.) Transporting the actual atoms themselves, as is done on Star Trek, just isn't possible. And if you could do it that way, "current ethical problems would pale in comparison," he said.
The laws of relativity don't rule out the possibility of time travel, but Professor Krauss said that the possibility would create serious paradoxes that no sensible universe would allow. Physicist Stephen Hawking once told him that if time travel were possible, we'd be inundated by visitors from the future. Dr. Krauss told the Wong Auditorium audience his response to Dr. Hawking had been, "They allwent back to the '60s and nobody noticed them."
A version of this article appeared in the March 31, 1999 issue of MIT Tech Talk (Volume 43, Number 24).