"Consider a world so cold," says Union Carbide Engineer Roger Thompson, "that the very air you breathe turns to liquid or freezes as solid as a block of ice, where steel is as brittle as glass, a rubber ball shatters when it hits the floor, and lead is an almost perfect conductor of electricity." The odd goings-on described by Engineer Thompson all occur in the far-out world of cryogenics—the science of ultra-low temperatures.
Although it has risen from the status of a laboratory novelty only within the past decade, cryogenics now occupies the attention of hundreds of scientists, has growing applications in industry and science and shows fascinating promise for the near future. Scientists are already talking about cryogenic technology that will make possible transmission lines that conduct electricity without power losses, switching elements that make computers incredibly faster and smaller, and high-speed trains that float on magnetic cushions.
More than Records. The cryogenic temperature range begins at a chilly— 150° F. and plummets to —459.7° F., or absolute zero, the point at which all thermal motion of the atom ceases. To attain these temperatures, scientists use expansion engines that compress gases, cool them and allow them to expand again, then repeat the cycle until they liquefy and eventually solidify. As the gases approach absolute zero, a sophisticated magnetization process extracts their remaining reservoir of heat. Because there will always be slight thermal motion of the atomic particles, scientists will never actually achieve absolute zero. But last July, Naval Research Laboratory Physicist Arthur Spohr reported achieving a record low temperature by chilling helium to within a millionth of a degree of absolute zero—3/10 of a millionth of a degree colder than the lowest temperature previously achieved.
More than records are at stake in making the closest possible approach to absolute zero. As the motion of atomic particles decreases with increasing cold, scientists can study the particles more closely and learn more about the forces that bind them together.
Extreme cold also produces the phenomenon of superconductivity, which scientists are putting to work in scores of applications. As temperatures approach absolute zero, the electrical resistance of many elements and compounds suddenly disappears. These substances become highly efficient conductors, and small voltages produce large currents that continue to flow indefinitely even after the power source has been withdrawn. Scientists can now envision a superconductive power-transmission line cooled by liquid helium that could carry 100 billion watts of direct current for hundreds of miles with no appreciable losses.