Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, July 15, 1993 TAG: 9309030392
SECTION: EXTRA PAGE: 3 EDITION: METRO
SOURCE: Joel Achenbach
DATELINE: LENGTH: Medium
Our own theory is that gravity doesn't even exist - some day there will be a press conference at which grim scientists will announce that all supposedly ``gravitational'' phenomena are actually the result of static electricity. They'll say the reason things fall to the ground is that the Earth has ``somehow been rubbed.''
Scientists like to say that gravity is a distortion and squeezing and stretching of the geometry of spacetime. Ignore them. That's just cocktail party talk. It's just as fair to say that gravity is a force of attraction that affects all matter.
Modern physics predicts that there should be gravity waves and gravity particles (gravitons), but so far we haven't actually found these things. We aren't even sure how fast gravity propagates across space. We desperately want to capture gravity, measure it, read it, but at this point we can't do a whole lot more than pull out the bathroom scale. Gravity remains invisible.
Here's the problem: Gravity penetrates everything. It goes right through you. It plows through brick, steel, lead. It blows through the Earth. The gravitational waves of the Big Bang are still scurrying around the cosmos with almost no disruption. Since nothing stops a gravity wave, there's no way to make a machine that detects one.
``Since they don't interact with anything, since nothing stops them, it's also hard to trap them and measure them,'' says Robbie Vogt, professor of physics at Caltech.
The reason vision exists is because light doesn't entirely penetrate objects. Some light waves are reflected, back into your eyes, and so we see things. If light didn't reflect, we wouldn't even have eyes. (We'd look really weird.) Gravity doesn't reflect at all.
Why gravity is like this is something we can't answer, other than to say that that's the kind of universe we live in. If it were otherwise - if the universe was not permeable to gravity - then it would be such a differently configured place that perhaps no intelligent life would arise to ask questions like this.
The big news is, we may soon capture some gravity and use it to look at the world in an entirely different way. Vogt is director of LIGO, for Laser Interferometer Gravitational Wave Observatory. The project is designed to measure the very slight contraction of space that represents a gravitational wave passing through the Earth.
Here's the idea: Suspend two quartz cylinders with mirrored surfaces 2.5 miles apart. Then watch 'em. Closely. What the scientists want to see is some indication that they are being affected by the powerful gravitational waves created by collapsing supernovas and colliding neutron stars and other exotic events far away. These waves will pass through only for a moment. Vogt estimates that the 2.5 mile separation between the cylinders will be changed by about a hundred millionth of the diameter of a single atom.
How could anyone measure such a tiny distance? It's hard. It hasn't been done yet. But they use lasers, and mirrors, and the mirrors bounce the laser beams back and forth thousands of times to magnify the measurement, and so forth. We imagine they also use smoke, somehow.
In any case, if we learn to ``see'' the universe through the ``gravitational wave band,'' there's no telling what we'll discover. When radio astronomy was invented after World War II, we discovered that the serene universe seen through telescopes was an illusion. Radio astronomy showed us a violent universe of quasars and pulsars and cataclysmic change.
Vogt says, ``We're trying to read the symphony that is on the gravitational waves.''
Which is what you should tell yourself the next time you get an unfortunate reading on the bathroom scale.
\ Joel Achenbach writes for the Style section of the Washington Post.
Washington Post Writers Group
by CNB