Scientists Are Back Making Something Out of Nothing
We tend to think of scientists as forward-looking folk. But surprisingly often, they get ahead only by going backward.
Science progresses, in other words, by going back to the future.
Consider the current controversy over the mysterious “repulsive” force that appears to pervade empty space, pushing apart galaxies at the edges of the cosmos.
Earlier this century, Einstein inserted a mathematical term for just such a force in his original theory of gravity. Later, when the force no longer seemed necessary to describe the universe, he took it out, calling it the greatest blunder of his life.
But scientists have been endowing empty space with powerful attributes since at least the ancient Greeks--who called it “quintessence,” or the fifth essence.
Newton and his contemporaries were convinced that empty space was filled with a “luminiferous ether” that carried light waves like air carries waves of sound. Alas, this ether would have had to possess all sorts of impossible properties. It would have to be stiff, like Styrofoam, in order to vibrate fast, but planets and other objects would have to move through it without leaving behind holes.
Einstein figured out a way for light to move through empty space without the ether--and the ether got hidden away into the history books with other discredited ideas such as alchemy.
The idea of ether “was not really wrong,” said physicist Jan Rafelski of the University of Arizona. “It was that we didn’t need it anymore as a medium for light.”
Now, it seems, the ether--or something like it--is making an encore, pushing the galaxies apart and eventually making the Milky Way a much more lonely place to live.
It’s not only the ghostly energy of nothing that keeps coming back to haunt us. Even Einstein’s ideas about relativity were not really new. Hundreds of years earlier, Galileo wrote at length about the illusions produced by moving frames of reference.
Someone trapped in the closed cabin of a steadily moving ship, he argued, could not tell whether he was moving--no matter what sort of experiments he performed: Drop a ball, watch fish swimming in a bowl, beam light across the cabin.
A person standing on a nearby dock might say the ship was moving, but the person in the ship could just as accurately say the ship was still and the dock was moving.
Indeed, the term “everything is relative” describes Galileo’s notions much better than Einstein’s. Einstein’s theories deal more directly with what is not relative--for example, the speed of light.
And what about Copernicus? Wasn’t he a forward-looking fellow? After all, he’s credited with showing us that the sun, not the Earth, was the center of the solar system.
But his motivations, according to Dartmouth physicist Marcelo Gleiser, were anything but forward-looking. Instead, Copernicus was trying to make the universe adjust to Plato’s ancient requirements that all heavenly bodies orbited in perfect circles, and Pythagoreans’ idea that a fire burned at the center of the heavens.
“[Copernicus’] thought reflects a willingness to shake the very foundations of the cosmological ideas of his time, but only in order to reach further back into the past,” writes Gleiser in “The Dancing Universe.”
“He was, in short, a conservative revolutionary. He could never have guessed that, by looking so far back, he would be propelling civilization into the future.”
Today, there’s nothing more futuristic in physics than string theory--the idea that everything in the universe is composed of unimaginably tiny strings vibrating in 10- or 11-dimensional space.
But adding extra dimensions, it turns out, is also old hat in physics. Einstein introduced a fourth dimension to explain gravity as the curvature of four-dimensional space-time.
Soon afterward, in 1919, Theodor Kaluza proposed that there might be more than four dimensions of space-time. In fact, he argued that both gravity and electromagnetism are higher-dimensional ripples in the fabric of space-time.
And so it goes. “Progress does not always move in the forward direction,” writes University of Warwick mathematician Ian Stewart, in “From Here to Infinity.”
Luckily, there are a few old ideas that never come back. Alchemy, for example. Ancient chemists tried to transform lead into gold, but today’s chemists know there’s no way to turn one element into another. Or is there?
Truth be told, radioactive atoms do it all the time--naturally. And modern chemists working with supercomputers and the equations of quantum mechanics create entirely new kinds of materials from scratch.
In science, as in life, it’s deja vu all over again.
