CATEGORY 5 INTO THE UNKNOWN

TRAVELINGFASTER

THAN LIGHTCLASSIFICATION BREAKINGTHE ULTIMATEBARRIER

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The idea of faster-than-light travel has long been ascience-fiction dream, ruled impossible by AlbertEinstein's Special Theory of Relativity. But the dream

could turn into reality according to some scientists, whothink that there are ways to break the light-speed barrierwithout necessarily breaking the laws of physics.Proposals for faster-than-light travel all depend ontwisting the fabric of space and time to find loopholes inEinstein's theory. It's a long shot that might just work.

SEE ALSO TIME TRAVEL, PARALLEL UNIVERSES, RELATIVITY

QUANTUM LEAPIn 1994, in a weirdexperiment involvingquantum effects onsubatomic particles,Gunther Nimtz ofCologne Universityin Germany claimedthat he transmitteda recording of aMozart symphonyby microwave adistance of 4.6 inches4.7 times faster thanthe speed of light.

TIME SIGNALTachyons aretheoretical subatomicparticles that alwaystravel faster thanlight. They have theinteresting property ofeffectively movingbackward in time, andsome scientists havesuggested that theycould be used to sendsignals into the past.

HOW TO CROSS THE GALAXY IN AN INSTANT

FOLDINGSPACE

one part of the universe and instantly emerge somewhereelse-perhaps even in another galaxy. Relative to normalspace, the ship has traveled much faster than light.

The second method, proposed in 1994 by physicistMiguel Alcubierre, uses powerful force fields to twist thespace around it. Alcubierre's so-called warp drive shrinksthe fabric of space-time in front of a ship and expands itbehind at the same rate. The ship does not "go" anywherein the usual sense of the word. Instead, it just sits quietlywhile the space-time around it "warps" in such a way asto bring the destination to the ship-very quickly.F aster-than-light (FTL) travel appears to be against the

fundamental rules of the universe. As any objectapproaches light-speed, its mass increases toward

infinity-and it requires infinite energy to accelerate itany farther. Even so, scientists can envision at least twoways around the speed limit, neither of which technicallybreaks the rules. Instead, both methods cheat by alteringthe geometry of the universe. According to scientists, suchrestructuring may well be possible.

The first method relies on the distortions in space-timethat result from a black hole's massive gravity to create awormhole-a shortcut between two points that wouldotherwise be separated by a vast gulf. These are nottunnels though ordinary space: They burrow through"hyperspace," a hidden dimension that we cannotsee. In theory, a ship could enter a wormhole in

SPACE WARP The warp drive of 511by squeezing the SPI

the ship (right) and stime behind it. The

stationary in the bubJtime that surround

moves through the u,~

Find a massive object-a blerk hole isperfect-with sufficient gravity tomake a deep well in space-time.

Fold your sheet of space-time until thebottom of your gravity well coincideswith another hole elsewhere.

link the two wells into a hyperspacetunnel. Pass through it. You havecrossed normal space faster than light.

HOWTOCRYou CAN ILLUSTRATE THE WORMH(LEFT). THE PAPER'S TWO DIMENIBRING AN EXTRA DIMENSION INTOMODERN WORMHOLE THEORY BEt(ONTAa, HE NEEDED A PLAUSIBL

VEGA. SAGAN TURNED TO PHYSICWORMHOLES THROUGH SPACE-TIMBLACK HOLE THAT DISTORTED THEOBJEa COULD CREATE PATHWAYS·CONVENIENTLY SITED NEAR THE EA

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Li.,., it'CIIt'ic:.n5Wormholes and warps may be scientifically plausibletheories, but they are a long way from becomingpractical engineering projects. Wormhole entrancescan exist only at the hearts of rotating black holes. Topass through one, a ship would have to be able tonullify the powerful gravitational forces there. If not,it would be stretched into an ultra-thin strand manymiles long-an unpleasant fate that theorists havedescribed as spaghettification.

The solution may ultimately lie in a bizarre

r Trek fame worksce-time in Iront ofetching the space-

ship itsell remainse 01 DllatD space-it. But the bubble

'verse at virtuallylimited velocities.

ATE A WORMHOLELE PRINCIPLE FOR YOURSElF WITH NOTHING MORE EXOTIC THAN A SHEET OF PAPER

ONS REPRESENT THE THREE DIMENSIONS OF SPACE. By FOLDING THE PAPER, YOUPLAY-AND TWO POINTS THAT WERE FAR APART ARE SUDDENLY ClOSE TOGETHER.N WITH SCIENTIST AND WRITER CARl SAGAN. FOR HIS SCIENCE-FIGION NOVELSPACE DRIVE TO MOVE HIS CHARAaERS 26 LIGHT-YEARS FROM EARTH TO THE STAR

KIP THORNE FOR ADVICE-AND THORNE, FASCINATED, WENT ON TO PROVE THATWERE BOTH POSSIBLE AND (ALMOST) PRAGICAL THORNE BEGAN WITH A ROTATING

PACE AROUND IT WITH ITS ENORMOUS GRAVITY. THEN HE SHOWED THAT SUCH ANROUGH ANOTHER DIMENSION TO A SECOND BLACK HOLE. WITH ONE HOLE

TH AND THE OTHER ORBITING VEGA, SAGAN'S PROBLEM WAS SOLVED.

theoretical material known as exotic matter, which hasnegative energy and negative mass-concepts as strangeas wormholes themselves. According to the laws ofphysics, exotic matter is not impossible, but no one knowswhere to find it, or even if it exists at all. The hardest partof any faster-than-light project may be finding out.

Warp drive engineers will be searching for exotic matter,too, since it is the only substance that will allow their

strange ship to survive the stresses of space-timedistortion. And the ship will have another problem

as it warps its way through the galaxy. If itencounters any ordinary matter-a little

interstellar dust, say-then that matterwill be squeezed to densities

approaching those of the Big Bangthat began the universe. An

instant later, the atoms willexplode in a devastating

blast of radiation,much to the

discomfort of thewarp-ship's

crew.

•••WE COULD TRAVEL FASTER THAN LIGHT?

Should faster-than-light (FTL) travel ever turn out tobe possible, we may have to get used to living in a

world of strange and head-spinning paradoxes. Fromsome points of view, travelers will arrive before theydepart. And similarly, certain effects will appear beforetheir causes.

Imagine three planets, called A, Band C. Planet A isthree light-years away from C, with B somewhere inthe middle, at a point one light-year from A and twolight-years from C. The people of B are keeping a closeeye (thanks to their powerful telescopes) on what theinhabitants of A and C are doing. They observe that C'sengineers are busily constructing an FTL spaceship inorbit around their planet. It's not an easy task, and theB scientists reckon that it will be at least a year beforethe project is completed. But a few days later, they turntheir telescopes on A-and observe the arrival of the C

spaceship, which was not due to be launched foranother 12 months.

In fact, the light that reaches the B telescopes from Cis already two years old. During that time, thespaceship has not only been built and launched, buthas made a faster-than-light journey to A, with plentyof time left over for light to carry the news of its arrivalback to B. So far as B is concerned, the C spaceship hasarrived before it departed.

The paradoxes get worse. The government of A,alarmed by C's new technology, sends in the marinesand captures the faster-than-light ship. Under newmanagement, the ship then speeds off back to Planet C,with orders to destroy C's orbiting shipyard. Withruthless precision, it quickly achieves its mission.Observers on B see the destruction through theirtelescopes-and sta\t banging their heads against the

wall. First, they saw an FTL ship arrive atA, when they knew it was stillunfinished at C. Next, they saw the sameship turn up again at C-and destroy theshipyard that built it, before the shipitself was even built.

B's scientists have had enough. Theydecide it would be better to live in auniverse where FTL travel was banned.

A stolen faster·than·light starship destroys theorbiting shipyard that constructed it with alaser'cannon-before the ship has even been built!This is only one of many paradoxes created byfaster·than·light travel.

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