Physics of the Impossible by Michio Kaku
Fusion will not completely solve the Earth’s energy crisis anytime in the near future; Pierre-Gilles de Gennes, French Nobel laureate in physics, has said, “We say that we will put the sun into a box. The idea is pretty. The problem is, we don’t know how to make the box.” But if all goes well, researchers are hopeful that within forty years the ITER may pave the way for commercialization of fusion energy, energy that can provide electricity for our homes. One day, fusion reactors may alleviate our energy problem, safely releasing the power of the sun on the Earth.
But even magnetic confinement fusion reactors would not provide enough energy to energize a Death Star weapon. For that we would need an entirely new design.
NUCLEAR-FIRED X-RAY LASERS
There is one other possibility for simulating a Death Star laser cannon with today’s known technology, and that is with a hydrogen bomb. A battery of X-ray lasers harnessing and focusing the power of nuclear weapons could in theory generate enough energy to operate a device that could incinerate an entire planet.
The nuclear force, pound for pound, releases about 100 million times more energy than a chemical reaction. A piece of enriched uranium no bigger than a baseball is enough to incinerate an entire city in a fiery ball—even though only 1 percent of its mass has been converted to energy. As we discussed, there are a number of ways of injecting energy into a laser beam. By far the most powerful of all is to use the force unleashed by a nuclear bomb.
X-ray lasers have enormous scientific as well as military value. Because of their very short wavelength they can be used to probe atomic distances and decipher the atomic structure of complicated molecules, a feat that is extraordinarily difficult using ordinary methods. A whole new window on chemical reactions opens up when you can “see” the atoms themselves in motion and in their proper arrangement inside a molecule.
Because a hydrogen bomb emits a huge amount of energy in the X-ray range, X-ray lasers can also be energized by nuclear weapons.
The person most closely associated with the X-ray laser is the physicist Edward Teller, father of the hydrogen bomb.
Teller, of course, was the physicist who testified before Congress in the 1950s that Robert Oppenheimer, who had headed the Manhattan Project, could not be trusted to continue work on the hydrogen bomb because of his politics. Teller’s testimony led to Oppenheimer’s being disgraced and having his security clearance revoked; many prominent physicists never forgave Teller for what he did.
(My own contact with Teller dates from when I was in high school. I conducted a series of experiments on the nature of antimatter and won the grand prize in the San Francisco science fair and a trip to the National Science Fair in Albuquerque, New Mexico. I appeared on local TV with Teller, who was interested in bright young physicists. Eventually I was awarded Teller’s Hertz Engineering Scholarship, which paid for my college education at Harvard. I got to know his family fairly well through visits to the Teller household in Berkeley several times a year.)
Basically, Teller’s X-ray laser is a small nuclear bomb surrounded by copper rods. The detonation of the nuclear weapon releases a spherical shock wave of intense X-rays. These energetic rays then pass through copper rods, which act as the lasing material, focusing the power of the X-rays into intense beams. These beams of X-rays could then be directed at enemy warheads. Of course, such a device could be used only once, since the nuclear detonation causes the X-ray laser to self-destruct.
The initial test of the nuclear-powered X-ray laser was called the Cabra test, and it took place in 1983 in an underground shaft. A hydrogen bomb was detonated whose flood of incoherent X-rays was then focused into a coherent X-ray laser beam. Initially, the test was deemed a success, and in fact in 1983 it helped to inspire President Ronald Reagan to announce, in a historic speech, his intent to build a “Star Wars” defensive shield. Thus was set in motion a multibillion-dollar effort that continues even to this day to build an array of devices like the nuclear-powered X-ray laser to shoot down enemy ICBMs. (Later investigation showed that the detector used to perform the measurements during the Cabra test was destroyed; hence its readings could not be trusted.)
Can such a controversial device in fact be used today to shoot down ICBM warheads? Perhaps. But an enemy could use a variety of simple, inexpensive methods to nullify such weapons (for example, the enemy could release millions of cheap decoys to fool radar, or spin its warheads to disperse the X-rays, or emit a chemical coating to protect against the X-ray beam). Or an enemy might simply mass-produce warheads to penetrate a Star Wars defensive shield.
So a nuclear-powered X-ray laser today is impractical as a missile defense system. But would it be possible to create a Death Star to use against an approaching asteroid, or to annihilate an entire planet?
THE PHYSICS OF A DEATH STAR
Can weapons be created that could destroy an entire planet, as in Star Wars? In theory, the answer is yes. There are several ways in which they might be created.
First, there is no physical limit to the energy that can be released by a hydrogen bomb. Here’s how this works. (The precise outlines of the hydrogen bomb are top secret and classified even today by the U.S. government, but the broad outlines are well known.) A hydrogen bomb is actually built in many stages. By properly stacking these stages in sequence, one could produce a nuclear bomb of almost arbitrary magnitude.
The first stage is a standard fission bomb, using the power of uranium-235 to release a burst of X-rays, as was done in the Hiroshima bomb. In the fraction of a second before the blast from the atomic bomb blows everything apart, the expanding sphere of X-rays outraces the blast (since it travels at the speed of light) and is then refocused onto a container of lithium deuteride, the active substance of a hydrogen bomb. (Precisely how this is done is still classified.) The X-rays striking the lithium deuteride causes it to collapse and heat up to millions of degrees, causing a second explosion, much larger than the first. The burst of X-rays from this hydrogen bomb can then be refocused onto a second piece of lithium deuteride, creating a third explosion. In this way, one could stack lithium deuteride side by side and create a hydrogen bomb of unimaginable magnitude. In fact, the largest hydrogen bomb ever built was a two-stage bomb detonated by the Soviet Union back in 1961, packing the energy of 50 million tons of TNT, although it was theoretically capable of a blast of over 100 million tons of TNT (or about five thousand times the power of the Hiroshima bomb).
To incinerate an entire planet, however, is something of an entirely different magnitude. For this, the Death Star would have to launch thousands of such X-ray lasers into space, and they would then be required to fire all at once. (By comparison, remember that at the height of the cold war the United States and the Soviet Union each accumulated about thirty thousand nuclear bombs.) The collective energy from such an enormous number of X-ray lasers would be enough to incinerate the surface of a planet. So it would certainly be possible for a Galactic Empire hundreds of thousands of years into the future to create such a weapon.
For a very advanced civilization, there is a second option: to create a Death Star using the energy of a gamma ray burster. Such a Death Star would unleash a burst of radiation second only to the big bang. Gamma ray bursters occur naturally in outer space, but it is conceivable that an advanced civilization could harness their vast power. By controlling the spin of a star well before it undergoes a collapse and unleashes a hypernova, one might be able to aim the gamma ray burster at any point in space.
GAMMA RAY BURSTERS
Gamma ray bursters were actually first seen in the 1970s, when the U.S. military launched the Vela satellite to detect “nukeflashes” (evidence of an unauthorized detonation of a nuclear bomb). But instead of spotting nukeflashes, the Vela satellite detected huge bursts of radiation from space. Initially this discovery set off a panic in the Pentagon: were the Soviets testing a new nuclear weapon in outer space? Later it was determined that these bursts of radiation were coming uniformly from all directions of the sk
When the Soviet Union broke apart in 1990, a huge body of astronomical data was suddenly declassified by the Pentagon, overwhelming astronomers. Suddenly astronomers realized that a new, mysterious phenomenon was staring them in the face, one that would require rewriting the science textbooks.
Since gamma ray bursters last from only a few seconds to a few minutes before they disappear, an elaborate system of sensors is required to spot and analyze them. First, satellites detect the initial burst of radiation and send the exact coordinates of the burster back to Earth. These coordinates are then relayed to optical or radio telescopes, which zero in on the exact location of the gamma ray burster.
Although many details must still be clarified, one theory about the origins of gamma ray bursters is that they are “hypernovae” of enormous strength, which leave massive black holes in their wake. It appears as if gamma ray bursters are monster black holes in formation.
But black holes emit two “jets” of radiation, one from the north pole and one from the south pole, like a spinning top. The radiation seen from a distant gamma ray burster is apparently one of the jets that is aligned toward the Earth. If the jet of a gamma ray burster were aimed at the Earth, and the gamma ray burster were in our galactic neighborhood (a few hundred light-years from Earth), its power would be enough to destroy all life on our planet.
Initially the gamma ray burster’s X-ray pulse would create an electromagnetic pulse that would wipe out all electronics equipment on the Earth. Its intense beam of X-rays and gamma rays would be enough to damage the atmosphere of the Earth, destroying our protective ozone layer. The jet of the gamma ray burster would then heat up temperatures on the surface of the Earth, eventually setting off monster firestorms that would engulf the entire planet. The gamma ray burster might not actually explode the entire planet, as in the movie Star Wars, but it would certainly destroy all life, leaving a scorched, barren planet.
Conceivably, a civilization hundreds of thousands to a million years more advanced than ours might be able to aim such a black hole in the direction of a target. This could be done by deflecting the path of planets and neutron stars into the dying star at a precise angle just before it collapses. This deflection would be enough to change the spin axis of the star so that it could be aimed in a certain direction. A dying star would make the largest ray gun imaginable.
In summary, the use of powerful lasers to create portable or handheld ray guns and light sabers can be classified as a Class I impossibility—something that is possible in the near future or perhaps within a century. But the extreme challenge of aiming a spinning star before it erupts into a black hole and transforming it into a Death Star would have to be considered a Class II impossibility—something that clearly does not violate the laws of physics (such gamma ray bursters exist) but something that might be possible only thousands to millions of years in the future.
4: TELEPORTATION
How wonderful that we have met with paradox. Now we have some hope of making progress.
—NIELS BOHR
I canna’ change the laws of physics, Captain!
—SCOTTY, CHIEF ENGINEER IN STAR TREK
Teleportation, or the ability to transport a person or object instantly from one place to another, is a technology that could change the course of civilization and alter the destiny of nations. It could irrevocably alter the rules of warfare: armies could teleport troops behind enemy lines or simply teleport the enemy’s leadership and capture them. Today’s transportation system—from cars and ships to airplanes and railroads, and all the many industries that service these systems—would become obsolete; we could simply teleport ourselves to work and our goods to market. Vacations would become effortless, as we teleport ourselves to our destination. Teleportation would change everything.
The earliest mention of teleportation can be found in religious texts such as the Bible, where spirits whisk individuals away. This passage from Acts in the New Testament seems to suggest the teleportation of Philip from Gaza to Azotus: “When they came up out of the water, the Spirit of the Lord suddenly took Philip away, and the eunuch did not see him again, but went on his way rejoicing. Philip, however, appeared at Azotus and traveled about, preaching the gospel in all the towns until he reached Caesarea” (Acts 8:36–40).
Teleportation is also part of every magician’s bag of tricks and illusions: pulling rabbits out of a hat, cards out of his or her sleeves, and coins from behind someone’s ear. One of the more ambitious magic tricks of recent times featured an elephant disappearing before the eyes of a startled audience. In this demonstration a huge elephant, weighing many tons, was placed inside a cage. Then, with a flick of a magician’s wand, the elephant vanished, much to the amazement of the audience. (Of course, the elephant really did not disappear. The trick was performed with mirrors. Long, thin, vertical mirror strips were placed behind each bar of the cage. Like a gate, each of these vertical mirror strips could be made to swivel. At the start of the magic trick, when all these vertical mirror strips were aligned behind the bars, the mirrors could not be seen and the elephant was visible. But when the mirrors were rotated by 45 degrees to face the audience, the elephant disappeared, and the audience was left staring at the reflected image from the side of the cage.)
TELEPORTATION AND SCIENCE FICTION
The earliest mention of teleportation in science fiction occurred in Edward Page Mitchell’s story “The Man Without a Body,” published in 1877. In that story a scientist was able to disassemble the atoms of a cat and transmit them over a telegraph wire. Unfortunately the battery died while the scientist was trying to teleport himself. Only his head was successfully teleported.
Sir Arthur Conan Doyle, best known for his Sherlock Holmes novels, was fascinated by the notion of teleportation. After years of writing detective novels and short stories he began to tire of the Sherlock Holmes series and eventually killed off his sleuth, having him plunge to his death with Professor Moriarty over a waterfall. But the public outcry was so great that Doyle was forced to resurrect the detective. Because he couldn’t kill off Sherlock Holmes, Doyle instead decided to create an entirely new series, featuring Professor Challenger, who was the counterpart of Sherlock Holmes. Both had a quick wit and a sharp eye for solving mysteries. But while Mr. Holmes used cold, deductive logic to break open complex cases, Professor Challenger explored the dark world of spirituality and paranormal phenomena, including teleportation. In the 1927 novel The Disintegration Machine, the professor encountered a gentleman who had invented a machine that could disintegrate a person and then reassemble him somewhere else. But Professor Challenger is horrified when the inventor boasts that his invention could, in the wrong hands, disintegrate entire cities with millions of people with a push of a button. Professor Challenger then uses the machine to disintegrate the inventor, and leaves the laboratory, without reassembling him.
More recently Hollywood has discovered teleportation. The 1958 film The Fly graphically examined what could happen when teleportation goes horribly awry. When a scientist successfully teleports himself across a room, his atoms mix with those of a fly that accidentally entered the teleportation chamber, so the scientist turns into a grotesquely mutated monster, half human and half fly. (A remake featuring Jeff Goldblum was released in 1986.)
Teleportation first became prominent in popular culture with the Star Trek series. Gene Roddenberry, Star Trek’s creator, introduced teleportation into the series because the Paramount Studio budget did not allow for the costly special effects needed to simulate rocket ships taking off and landing on distant planets. It was cheaper simply to beam the crew of the Enterprise to their destination.
Over the years any number of objections have been raised by scientists about the possibility of teleportation. To teleport someone, you would
TELEPORTATION AND THE QUANTUM THEORY
According to Newtonian theory, teleportation is clearly impossible. Newton’s laws are based on the idea that matter is made of tiny, hard billiard balls. Objects do not move until they are pushed; objects do not suddenly disappear and reappear somewhere else.
But in the quantum theory, that’s precisely what particles can do. Newton’s laws, which held sway for 250 years, were overthrown in 1925 when Werner Heisenberg, Erwin Schrödinger, and their colleagues developed the quantum theory. When analyzing the bizarre properties of atoms, physicists discovered that electrons acted like waves and could make quantum leaps in their seemingly chaotic motions within the atom.
The man most closely associated with these quantum waves is the Viennese physicist Erwin Schrödinger, who wrote down the celebrated wave equation that bears his name, one of the most important in all of physics and chemistry. Entire courses in graduate school are devoted to solving his famous equation, and entire walls of physics libraries are full of books that examine its profound consequences. In principle, the sum total of all of chemistry can be reduced to solutions to this equation.