Zero - Charles Seife [71]
Rockets bring their own supply of stuff to push against. Rocket fuel burns in the engine and is sent out the back of the rocket, driving the spaceship forward, just as the rush of air out of a balloon sends it flying around the room. But tossing away fuel is an expensive and cumbersome way to go places, and even modern improvements on the chemical engine, such as engines that use electricity to throw stuff out the back of a rocket, are unable to provide the fuel efficiency to send probes to distant stars in a reasonable amount of time. To get even to the nearest star, you would need an enormous amount of fuel to jettison out the back of the rocket—a tremendous waste.
Physicist Marc Millis heads NASA’s Breakthrough Propulsion Project and hopes to overcome this problem with the physics of zero. Unfortunately, the zeros of black holes—singularities—look like unlikely candidates in the short term. Not only is it extremely difficult to create a naked singularity that a wormhole needs, but it also appears that even a naked singularity will tear space travelers to shreds. In 1998 two physicists from the Hebrew University in Jerusalem showed that even a spinning or charged black hole—with a nice, ring-shaped singularity—will kill an astronaut, thanks to mass inflation. As you fall toward the singularity, the black hole’s mass appears to grow and grow to infinity. The gravitational tug is so strong that you’d be torn apart in a fraction of a second. Wormholes would be hazardous to your health.
Even if the zeros at the center of black holes don’t provide an easy way to travel through space, the zero of quantum mechanics provides an alternative: the zero-point energy might be the ultimate fuel. It is here that the mainstream of physics ends and the fringe begins.
According to Millis, astronauts might harness the energy in the vacuum to push a spaceship, just as mariners harnessed the wind to drive a frigate. “I’m making an analogy to the Casimir effect, where you can push plates together with a noticeable radiation pressure from the vacuum,” he says. “If there were any way to get asymmetric forces out of that, where you get force in one direction and not the other, you’d get a propulsive force.” Unfortunately, so far the Casimir effect seems to be symmetric; both plates collapse and pull each other together. The action of one has an equal and opposite reaction on the other. But if there were some sort of quantum sail, a one-way mirror that reflected virtual particles on one side but let them pass unhindered through the other, the vacuum energy would push the whole object toward the unreflective half of the sail. Millis admits that nobody has any clue how to do this. “There are no theories how to engineer the device,” he says sadly.
The problem is that the laws of physics say you can’t get something for nothing; just as the frigate lowers the speed of the wind, the quantum sail would have to lower the energy of the vacuum. How can you modify nothing?
Harold Puthoff, the director of the Institute for Advanced Studies in Austin, Texas, believes that a quantum sail would simply alter the properties of the vacuum. (Puthoff is best known for his 1974 paper in Nature that purported to prove that Uri Geller and other psychics could view objects remotely—without their eyes. This conclusion was not in the mainstream of science.) “The vacuum decays to a slightly lower state,” says Puthoff. If so, then quantum sails are just the beginning; it would be possible to make engines that run solely on zero-point energy. Their only drawback would be that the fabric of the universe would fall apart. Slowly. “We’d never make a dent. It’s like scooping up cupfuls of water from the ocean,” says Puthoff.
It might also destroy the universe.
There is no question that the vacuum has energy; the Casimir force is witness to that fact. But is it possible that the energy of the vacuum is truly the lowest possible energy? If not, danger might be lurking in the vacuum. In 1983 two scientists