Ethereal Cat

The old scientific concept of the ether --an all-pervading medium which transmits light and gravitational force--is a nine-lived cat. Supposedly killed off several times, it still keeps pattering around science's pantry. Last week Dr. Herbert Eugene Ives, an astute and merry physicist who works for Bell Telephone Laboratories in Manhattan, gave the old tabby a good strong shot of mathematical adrenalin.

In 1881 Michelson and Morley raced two beams of light against each other with an interferometer (a light splitter). The beams were at right angles. Idea was that if the earth, in its revolution around the sun, was actually traveling through a sea of ether, the effect of ether-drag should perceptibly slow up one of the beams. But the two beams finished th--e race practically neck & neck. This looked like a mortal wallop for the ether theory. Einstein's Relativity theories (1905-15) seemed another deadly stroke, for they dispensed with the ether as unnecessary. In the relativistic view there is no such thing as absolute motion, therefore no need of a fixed frame of reference, such as the ether. It became fashionable for scientific popularizers to make fun of the ether as a ridiculous, shivering jelly. When Albert Einstein and Leopold Infeld wrote their book for laymen on the evolution of physics (TIME, April 4, 1938), they whimsically treated the ether as an unprintable vulgarism, the "e--r."

Professor Dayton Clarence Miller of Cleveland was one of those who refused to give up his ether. He repeated the Michelson-Morley experiment with delicate interferometers floating on pools of mercury, got positive results which convinced him that the earth is in absolute motion, through an ether sea, at a speed of several hundred miles a second. But his findings were not generally accepted.

When Einstein was putting together the framework of Relativity, he was fascinated by the Larmor-Lorentz-Fitzgerald theory that when a clock is in motion it slows down slightly--too slightly to be detected by ordinary means. This theory was based on the idea of a fixed frame of reference, such as the ether. Einstein incorporated the theory in the Relativity structure, as a consequence not of absolute motion but of relative motion--that is, of the clock's motion relative to a hypothetical observer. For a long time there was no experimental confirmation of the Larmor-Lorentz-Fitzgerald slowdown. Then, about two years ago, Dr. Ives used glowing particles of hydrogen gas as "atomic clocks," showed that their rate of oscillation slows down when the particles themselves are speeded up to velocities around 1,000 miles a second (TIME, May 9, 1938). The experiment was spectacular but the conclusion ambiguous. Was the slowdown a result of absolute motion, or of relativistic motion?

In Science last week Dr. Ives declared flatly that his experiment "does detect the ether." He admires Einstein's genius, but he is not constrained to think the Master infallible. In a complicated argument, he undertook to show that the relativistic abolition of the ether is based on a mere convention of measurement. Other conventions of measurement could have served just as well, and they could have been based on an ether as a fixed frame of reference.

Dr. Ives may find it hard to get a quorum of physicists to agree with him, but his view will command respectful attention. Thanks to him, the battered old ethereal cat was looking better than it had for years.

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