Hyperspace (31 page)

This solution, however, left several questions unanswered. Some Flatlanders
still wanted experimental proof, not just theoretical calculations, that the pieces could really be assembled into this gemstone. This theory gave a concrete number for the energy it would take to build powerful machines that could hoist these fragments “up” off Flatland and assemble the pieces in three-dimensional space. But the energy required was about a quadrillion times the largest energy source available to the Flatlanders.

For some, the theoretical calculation was sufficient. Even lacking experimental verification, they felt that “beauty” was more than sufficient to settle the question of unification. History had always shown, they pointed out, that the solution to the most difficult problems in nature had been the ones with the most beauty. They also correctly pointed out that the three-dimensional theory had no rival.

Other Flatlanders, however, raised a howl. A theory that cannot be tested is not a theory, they fumed. Testing this theory would drain the best minds and waste valuable resources on a wild-goose chase, they claimed.

The debate in Flatland, as well as in the real world, will persist for some time, which is a good thing. As the eighteenth-century philosopher Joseph Joubert once said, “It is better to debate a question without settling it than to settle a question without debating it.”

The eighteenth-century English philosopher David Hume, who was famous for advancing the thesis that every theory must be grounded on the foundation of experiment, was at a loss to explain how one can experimentally verify a theory of Creation. The essence of experiment, he claimed, is reproducibility. Unless an experiment can be duplicated over and over, in different locations and at different times with the same results, the theory is unreliable. But how can one perform an experiment with Creation itself? Since Creation, by definition, is not a reproducible event, Hume had to conclude that it is impossible to verify any theory of Creation. Science, he claimed, can answer almost all questions concerning the universe except for one, Creation, the only experiment that cannot be reproduced.

In some sense, we are encountering a modern version of the problem identified by Hume in the eighteenth century. The problem remains the same: The energy necessary to re-create Creation exceeds anything available on the planet earth. However, although direct experimental
verification of the ten-dimensional theory in our laboratories is not possible, there are several ways to approach this question indirectly. The most logical approach was to hope that the superconducting supercollider (SSC) would find subatomic particles that show the distinctive signature of the superstring, such as supersymmetry. Although the SSC could not have probed the Planck energy, it might have given us strong, indirect evidence of the correctness of superstring theory.

The SSC (killed off by formidable political opposition) would have been a truly monstrous machine, the last of its type. When completed outside Dallas, Texas, around the year 2000, it would have consisted of a gigantic tube 50 miles in circumference surrounded by huge magnets. (If it were centered in Manhattan, it would have extended well into Connecticut and New Jersey.) Over 3,000 full-time and visiting scientists and staff would have conducted experiments and analyzed the data from the machine.

The purpose of the SSC was to whip two beams of protons around inside this tube until they reached a velocity very close to the speed of light. Because these beams would be traveling clockwise and counter-clockwise, it would have been a simple matter to make them collide within the tube when they reached their maximum energy. The protons would have smashed into one another at an energy of 40 trillion electron volts (TeV), thereby generating an intense burst of subatomic debris analyzed by detectors. This kind of collision has not occurred since the Big Bang itself (hence the nickname for the SSC: “window on creation”). Among the debris, physicists hoped to find exotic subatomic particles that would have shed light on the ultimate form of matter.

Not surprisingly, the SSC was an extraordinary engineering and physics project, stretching the limits of known technology. Because the magnetic fields necessary to bend the protons and antiprotons within the tube are so exceptionally large (on the order of 100,000 times the earth’s magnetic field), extraordinary procedures would have been necessary to generate and maintain them. For example, to reduce the heating and electrical resistance within the wires, the magnets would have been cooled down nearly to absolute zero. Then they would have been specially reinforced because the magnetic fields are so intense that otherwise they would have warped the metal of the magnet itself.

Projected to cost
11 billion, the SSC became a prized plum and a matter of intense political jockeying. In the past, the sites for atom smashers were decided by unabashed political horse trading. For example, the state of Illinois was able to land the Fermilab accelerator in Batavia, just outside Chicago, because (according to
Physics Today
) President
Lyndon Johnson needed Illinois senator Everett Dirkson’s crucial vote on the Vietnam War. The SSC was probably no different. Although many states vigorously competed for the project, it probably came as no surprise that in 1988 the great state of Texas landed the SSC, especially when both the president-elect of the United States and the Democratic vice-presidential candidate came from Texas.

Although billions of dollars have been spent on the SSC, it will never be completed. To the horror of the physics community, the House of Representatives voted in 1993 to cancel the project completely. Intense lobbying failed to restore funding for the project. To Congress, an expensive atom smasher can be seen in two ways. It can be a juicy plum, generating thousands of jobs and billions of dollars in federal subsidies for the state that has it. Or it can be viewed as an incredible boondoggle, a waste of money that generates no direct consumer benefits. In lean times, they argue, an expensive toy for high-energy physicists is a luxury the country cannot afford. (In all fairness, though, funding for the SSC project must be put into proper perspective. Star Wars funding for just 1 year costs
4 billion. It costs about
1 billion to refurbish an aircraft carrier. A single space-shuttle mission costs
1 billion. And a single B-2 stealth bomber costs almost
1 billion.)

Although the SSC is dead, what might we have discovered with it? At the very least, scientists hoped to find exotic particles, such as the mysterious Higgs particle predicted by the Standard Model. It is the Higgs particle that generates symmetry breaking and is therefore the origin of the mass of the quarks. Thus we hoped that the SSC would have found the “origin of mass.” All objects surrounding us that have weight owe their mass to the Higgs particle.

The betting among physicists, however, was that there was an even chance that the SSC would find exotic particles beyond the Standard Model. (Possibilities included “Technicolor” particles, which lie just beyond the Standard Model, or “axions,” which may help to explain the dark matter problem.) But perhaps the most exciting possibility was the sparticles, which are the supersymmetric partners of ordinary particles. The gravitino, for example, is the supersymmetric partner of the graviton. The supersymmetric partners of the quark and lepton, respectively, are the squark and the slepton.

If supersymmetric particles are eventually discovered, then there is a fighting chance that we will be seeing the remnants of the superstring itself. (Supersymmetry, as a symmetry of a field theory, was first discovered in superstring theory in 1971, even before the discovery of supergravity. In fact, the superstring is probably the only theory in which
supersymmetry and gravity can be combined in a totally self-consistent way.) And even though the potential discovery of sparticles will not prove the correctness of superstring theory, it will help to quiet the skeptics who have said that there is not one shred of physical evidence for superstring theory.

Since the SSC will never be built, and hence will never detect particles that are low-energy resonances of the superstring, then another possibility is to measure the energy of cosmic rays, which are highly energetic subatomic particles whose origin is still unknown, but must lie deep in outer space beyond our galaxy. For example, although no one knows where they come from, cosmic rays have energies much larger than anything found in our laboratories.

Cosmic rays, unlike the controlled rays produced in atom smashers, have unpredictable energies and cannot produce precise energies on demand. In some sense, it’s like trying to put out a fire by either using hose water or waiting for a rainstorm. The hose water is much more convenient: We can turn it on any time we please, we can adjust the intensity of the water at will, and all the water travels at the same uniform velocity. Water from a fire hydrant therefore corresponds to producing controlled beams in atom smashers. However, water from a rainstorm may be much more intense and effective than water from a fire hydrant. The problem, of course, is that rainstorms, like cosmic rays, are unpredictable. You cannot regulate the rainwater, nor can you predict its velocity, which may fluctuate wildly.