Anti-Gravitation

The abolition of the principle of parity (TIME, Jan. 28) threw physics into an enjoyable turmoil from which it has not yet emerged. If long-sacred parity was laid low, the physicists argued eagerly, why shouldn't other lordly laws bite the dust too? Even gravitation, supposed to be pretty well explained by Einstein's general relativity, might be vulnerable. Last week the top award ($1,000) of the Gravity Research Foundation, New Boston, N.H. went to a paper by Physicist Philip Morrison of Cornell and Astronomer Thomas Gold of Harvard which argues that somewhere in the universe there may be anti-gravitation as a property of antimatter.

Push v. Weight. Professors Morrison and Gold start off by challenging one of the most basic laws of all, the principle of equivalence. According to this rule, on which general relativity is built, a body's inertial mass (resistance to a push) is the same in a given gravitational field as its gravitational mass (weight). Morrison and Gold admit that every experiment tried so far has shown the two kinds of mass to be precisely equivalent, but they think the apparatus used may have been biased in favor of equivalence. Anti-matter,* they point out, is just as respectable as ordinary matter, but none of it exists in physical laboratories, or in the solar system, or even in the Milky Way galaxy. Since it turns into a flash of energy when it encounters ordinary matter, the nearest place where antimatter could exist permanently is in a foreign galaxy made entirely of it. In this case it would be too far away to have a detectable influence on man's experiments.

Therefore, argue Morrison and Gold, conditions in earthly laboratories may be too special to trust. Gravitation might act differently if more antimatter were around. A sample of antimatter, for instance, might retain its inertial mass but be repelled instead of attracted by the earth's gravitational field. Its weight would be less than nothing; it would actually tend to lift itself. In an "anti-galaxy," a bit of ordinary matter would be repelled in the same way.

After elaborate mathematical reasoning, Morrison and Gold speculate that the universe may consist of both kinds of matter. Both antimatter and ordinary matter may have been created at the same time, and are perhaps still being created. Even if the atoms of opposite type are born in the same parts of space, they will seldom meet and suffer annihilation. Gravitational attraction will pull similar atoms together, while antigravitational repulsion will push dissimilar ones apart. The final result will be the segregation of matter and antimatter in separate galaxies.

Duel in the Sky. For all astronomers know, say Morrison and Gold, half of the galaxies may be made of antimatter. They will be pushing their neighbors away by antigravity, but the light that comes from them will reveal nothing unusual about them. Only when galaxies of hostile type happen to collide in spite of anti-gravity will their matter interact violently. This may be happening. Several odd objects deep in space, e.g., the M 87 galaxy, seem to get large amounts of energy from an unknown source. These may be pairs of hostile galaxies, fighting vast duels of annihilation.

*Ordinary matter has positively charged protons at the center of its atoms and negative electrons circling around them. Antimatter has negative antiprotons surrounded by positrons (positive electrons). No antimatter has been created yet, but all necessary antiparticles have been found, and physicists believe that these can unite to form anti-matter.

This file is automatically generated by a robot program, so reader's discretion is required.