By Alistair Highet
Boyd Mallett, in the words of his son, "was the best." After a stint in the Army, Boyd became a television technician at a time when TV was the technology of the future.
He was "the repairman to the stars," his son Dr. Ronald Mallet laughs. Then he gets out of his broad desk chair to gather some photographs. One is of his handsome father in the Army, smiling under a helmet. Others are autographed photographs from movie and Broadway stars of the 1950s--including a young Walter Matthau with his hair slicked back--thanking their friend Boyd for coming to fix their TV at a moment's notice.
But Boyd Mallett lived and played hard. A heavy smoker, he died of a heart attack at the age of 33 when his son, now a distinguished professor of physics at the University of Connecticut, was only 10."I really loved my father, and he was fun," says Mallett. "That was a terrible period for me."
For solace, like a lot of smart kids, Ronald Mallett turned to books, particularly the H.G. Wells landmark 1895 novel The Time Machine, where a young scientist, overcome with grief at the death of his fiancé, builds a carriage out of brass and crystal that allows him to hurtle back and forth in time. Long before Albert Einstein worked out the math, Wells, in his novel, theorized that time was a fourth dimension that could be moved through. "That became a kind of fascination for me," Mallett continues. "I had this idea that if I could go back in time and see my father, I could talk to him and help keep him alive."
Nearly 50 years later, Mallett may be on the verge of building the world's first operative "time machine," though it will bear little relation to that of Wells, or to the DeLorean sports car of the movie Back to the Future, or the Tardis of Dr. Who or any of the other hundreds of time traveling mechanisms that have been imagined since Wells first took a crack at it.
Mallett's machine, as laid out in his May 2000 paper in Physics Letters entitled "Weak gravitational field of the electromagnetic radiation in a ring laser," is based on Einstein's formulation that light and matter are both forms of energy.
We know that matter can bend space-time and according to Einstein's theory, matter and light are both forms of energy. So why can't light bend space-time?
This fall, with UConn colleague Dr. Chandra Raychoudri, Mallett will begin work on building a "ring laser"--basically, a device that will create a circulating light beam, perhaps within a photonic crystal that will bend the light's trajectory and slow it down.
Then, a neutron particle will be sent into the space in the center of the beam. In short, the beam--perhaps two beams in one model, with the light traveling in opposite directions--is expected to twist the space-time inside the circle into a loop. Think of a spoon stirring thick gravy in a pot and creating a vortex, only the vortex in this case is the fabric of space-time twisting, with past, present and future, circling one another so that the future precedes the past.
Then--and while this might not seem very exciting--a neutron, a small particle of matter--will be sent into the center of the beam. If its spin is affected, then it is being affected by warped space-time.
In a further experiment that Mallett has considered, two identical samples of a radioactive substance could be put into the center of the ring, one going in the direction of the beam. The other in the opposite direction. Since radioactivity decays at a measurable rate, it would be possible to measure, in effect, the time that both particles had experienced within the beam. If the time proves to be different, then time will have been measurably altered.
Eventually, says Mallett, "what would be neat is if you saw another neutron in there that you hadn't introduced yet." In essence, the same neutron "visiting itself from the future." So you've moved a neutron. So what?
What Mallett will have shown--if it works--is that the fabric of time itself can be altered by light, and a thing can be moved into the past. If it works for a neutron, in theory, it would work for you and me.
Imagine then--and put aside the engineering problems for a moment--a machine big enough to walk into. As you would walk forward within the confines of the light beam, (see diagram below) you'd have the impression of moving forward, but because of the space-time vortex, you'd actually be moving backward. You could walk back through time--maybe even passing yourself as you entered the ring.
Mallett's proposition has generated considerable popularity; The Christian Science Monitor, Village Voice and Boston Globe have all taken note. There are also a lot of skeptics. Mallett invites them. This is academia after all, and in serious science, you want to have your ideas doubted and tested.
"My problem with Ron Mallet's ideas is that I don't know how it is going to be possible to warp the space-time with his laser," says Robert Ehrlich, author of Nine Crazy Ideas in Science and a professor at George Mason University.
It is true that space time is not empty, but is a kind of fabric, and that "matter tells space how to curve, and the curved space tells light how to move," says Ehrlich, citing a popular short explanation of how the universe works, but he adds: "I don't know that light can distort gravity in this way. I would be very skeptical about his plan."
Allegheny College physicist Shafiqur Rahman is also skeptical. He says that what is missing at this point is a "quantum theory" for how gravity works. In other words, we don't have a sufficient grasp of the specific relation between mass and the experience of gravity to predict how light would affect time. But he adds, "But we could have an experiment that shows it, that's true. We could have an experiment that shows travel into the past without a theory."
What is not really controversial in the world of contemporary physics is that time travel is theoretically possible. Indeed, travel into the future has already been proven. The respectability of such theorizing is relatively new.
In fact, Mallett kept his private fascination with time travel "a secret," through most of his career, he confides. "I wanted to be taken seriously as a physicist, and not a crackpot."
Mallett is a big, open kind of man. His home office--in a tasteful Victorian not far from the university--with its comfortable padded chair parked before an impressive computer, is the perfect meditative chamber for a man concerned with the nature of time. It has a remarkable stillness to it, with books, software and busts of classical composers on the bookshelves. Mallett plays the piano.
There is also a small photograph of Marilyn Monroe on the wall. Einstein, once asked to explain relativity, said: "When you sit with a nice girl for two hours, it seems like two minutes; when you sit on a hot stove for two minutes, it seems like two hours--that's relativity."
After his Ph.D. in physics from Penn State in 1973, Mallett then spent a few years making lasers for United Technologies before joining the UConn faculty. It wasn't until 1998 that he thought about writing a popular book about time travel, and discovered that "there was a ton of serious work being done on this stuff."
All of that serious work is based on the work of Einstein, and to understand it--if you don't grasp the math (and few of us do)--means throwing out most of the operating assumptions that we have about how the universe we move around in really works.
Travel to the Future Already Possible
Most of us live comfortably in the world of Isaac Newton. Apples falls from trees because they are attracted by "gravity," the pull of the Earth on things. This works pretty well for most of what we do.
So, too, do we believe that time is a kind of constant. It moves at the same rate for all things at the same time, or in Newton's words, time is "flowing equally without relation to anything external."
But all of this was problematized at the turn of the 19th century by the discovery that the speed of light was a constant, 186,000 miles per second.
Since light speed is a constant, time and distance become suddenly things that stretch and contract in relation to light and motion.
Think of it this way. Say there are two cars on a highway with floodlights on the roof. One car is stationary, and the other is moving toward you at 100 miles an hour. If the distance and the time are constants without relation to anything external then the light on the moving car should reach you at 186,000 miles per second, plus 100 miles an hour. It should reach you before the light from the stationary car. But it doesn't.
What that means is that the time and the space between you and the cars contract based on the speed of the car. In fact, mass, velocity and time are all relative to the speed of light, and they all change depending on the speed that an object is traveling. That's the essence of the theory of special relativity.
Not that this has much effect on us at the speeds we are dealing with in our daily life. Still, travel into the future has already been proven. In 1975, Professor Carrol Alley tested Einstein's theory by using two synchronized atomic clocks--one on an airplane and the other on the ground. At the end of the flight, the one on the plane was behind the one on the ground. Time had slowed for the clock on the plane--it had traveled forward in time.
Princeton professor J. Richard Gott notes in his book Time Travel in Einstein's Universe that the world's most accomplished time traveler is the cosmonaut Sergie Avdeyev, who was on board the MIR space station for 748 days. Gott calculated that Avdeyev, traveling at 17,000 miles per hour for more than two years, traveled into the future by about 1/50th of a second.
Big deal. True, a miniscule amount of time. But what if it were possible to travel at light speed--put aside the technical problems, the massive amounts of energy required, and the tremendous friction that such a vessel would encounter as the universe around it got increasingly flat and heavy.
British physicist Steven Preston notes on his website that in a Newtonian Universe--where time flows equally with regard to everything--a trip to Andromeda, some 2.2 million light years away, would take about 2,065 years.
But because of special relativity, it might take a spaceship an entire year to accelerate to the speed of light, so 365 days. But after that period, it would take no time at all to reach Andromeda. The distance would have shrunk to zero. So it would take a year for an astronaut to reach Andromeda and a year to get back. Two years. But his twin brother on the ground would have been dead for just under 2.2 million years. That's travel into the future and it is consistent with the laws of nature.
The Grandfather Paradox
Travel into the past presents a host of other problems. A man decides that he wishes he had never been born. In fact, he wishes that his parents had never been born. He goes into a time machine and travels back to a time before his grandfather got married. He walks up to his grandfather on the street and shoots him dead. Does he then pop out of existence himself? How could he have gone back to kill his grandfather in the past, if in effect, having killed his grandfather, he never existed?
This is the grandfather paradox and it is one of the philosophical sticking points when thinking about travel into the past. It's a paradox that has bedeviled all science fiction explorations of the issue, like in the film Back to the Future where the main character finds himself disappearing when his mother--just a high school student--starts to take a romantic interest in him instead of the boy that would turn out to be his father.
But theoretically, the idea that travel into the past is possible has been embraced by many respectable physicists.The science of this again originates with Einstein and the general theory of relativity. What we think of as gravity is really the effect of mass on space-time.
Think of a bowling ball on a trampoline, says Mallet (see diagram above). Space has elasticity, like the surface of the trampoline. If you put a smaller ball on the trampoline, it will roll toward the bowling ball.
Time slows down the closer one is to a large mass. A clock on earth moves slower than a clock running on an empty spaceship, floating between galaxies. So theoretically, a very great mass--if it could be made to spin in the right direction--could make time go backwards.
So where do you get this enormous mass?
Black holes, or "wormholes" are the answer that most physicists talk about, in large part due to the late Carl Sagan, a Cornell astronomer and the author of the 1985 novel Contact. Sagan wanted his characters to travel from a point near the Earth to a point near the star Vega, and theorized that the travel would take place through a black hole--a swirling, gravitational vortex of infinite density in space that is created by a star falling in on itself. Not even light escapes, and a black hole would certainly suck you in very, very fast.
Sagan wasn't sure about the science so he contacted CalTech physicist Kip Thorne to ask him how it might work. Thorne sat down to prove that it was nonsense, but was forced to concede that theoretically, it could happen--and that traveling through space this way could also mean traveling through time, particularly if you could go through a "wormhole," a sort of tube through space and time with black holes at either end.
Engineering such a thing is problematic to say the least, and the simple beauty of Mallett's idea is that since light and matter are both forms of energy, he can create a small vortex with light, without having to deal with enormous mass.
But if there is time travel, why aren't we inundated with visitors from the future? And how do we solve the grandfather paradox? If Mallett could go back and save his father, he wouldn't become a physicist, and so wouldn't build a time machine, and wouldn't go back to save his father?
Allegheny College physicist Rahman says there are several ideas that physicists kick around to deal with these paradoxes.
First, we may be inundated with time travelers and not be aware of it. Maybe that's what UFOs are.
Another is one proposed by Cambridge's Stephen Hawking who has proposed a "chronology protection conjecture." In essence, that there is a law of nature that simply prevents people from tinkering with the past. You go back to shoot your grandfather and the gun jams, then you miss, then he gets on a bus ... and so on.
Another idea--one favored by Mallett among others, and based on quantum physics--is that there are limitless universes, where all probabilities are actualized. In other words, in one universe you go back in time and kill your grandfather, and in another you don't. In one Universe Hitler decided not to invade Russia in 1941, and so he won the war. And in another universe, Lee Harvey Oswald really did shoot Kennedy, and so on.
While this is a favored view, it is hard to accept on the basis of common sense. Says Rahman: "That means that every second there has to be an infinite number of splits, you are talking about more universes than particles in the universe. More matter has to be created all the time. It sounds difficult."
Then there is another possibility, one that is more chilling perhaps, and more likely, and one attributed to Italian physicist Enrico Ferme. "It may be that technological civilizations don't have the life span that they can develop time travel," Rahman says. "Civilizations burn fossil fuels, which leads to a greenhouse problem, and the end of the civilization for instance. There are mechanisms in place that mean civilizations don't last long enough."
So a society is on the verge of time travel when pollution destroys it. A new civilization scratches its way out of the rubble, and reaches a point where it is on the verge of time travel, when it collapses, and so on. None of these paradoxes worry Mallett very much. He thinks the "many worlds theory" of splits in the universe is consistent with physics, and that just because we don't understand how the universe works, doesn't mean that time travel is out of the question.
In fact, Mallett is optimistic that a real time machine that could transport a person will one day be built. "It would just be a problem of engineering," he says. "When the Wright brothers invented the airplane it only flew a few yards at first, and now look," says Mallett. "We make the effort to overcome the engineering obstacles."
So could Mallett possibly go back and see his father again? No, he says, it isn't possible. You couldn't go back in time to a time before a time machine was built. "So I don't think we can go back any further than when we have a time machine that works."
But if Mallett's design is successful, it will be a major scientific advance, always associated with the story of Boyd Mallett. In a sense, the hard-living and fun-loving Boyd Mallett will live forever in the story of the beginning of time travel, and his son will have saved the memory of his father from time's ravages."It comes full circle," Mallett nods and smiles as he reflects on the ironies. "It's quite a story."