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Phenomena, Comment & Notes

Today's physics appears to allow outrageous possibilities: faster-than-light travel across the galaxy, for example, or even our learning to make new universes to specification

On bad days I used to joke about the Universe being the work of a graduate student who, frankly, is not doing all that well. A model of farfetchedness, I thought. Now, however, unexpected support has come from Edward R. Harrison, a cosmologist at the University of Massachusetts, Amherst. He writes in the Quarterly Journal of the Royal Astronomical Society that yes, our universe may well have been created by intelligent beings in another universe. That assertion does nothing to explain how the whole thing began. It just moves the question back a step: Where did the universe inhabited by those intelligent beings come from? But Harrison's idea would explain some very strange things about our universe, such as how exactly right for life it is.

The history of the Universe has been summed up thusly: "Hydrogen is a light, odorless gas, which, given enough time, turns into people." When our universe began, it consisted mostly of hydrogen. That gas condensed into galaxies of stars, in whose cores heat and pressure fused atoms into heavier elements, including those necessary for life. Some of those stars exploded, spewing the heavier elements out into space. New stars and planets formed, including our own. On one of those planets, life appeared. Harrison contends that none of it could have happened unless all the physical constants (the speed of light, the charge and mass of the electron, and similar numbers) were just right. Reviewing the work of a long line of cosmologists, Harrison sums up what has come to be known as the Anthropic Principle: the Universe is the way it is because we exist. He explains: "In a universe containing luminous stars and chemical elements essential for the existence of organic life, the physical constants are necessarily precisely adjusted (or finely tuned). Slight deviations from the observed values could result in a starless and lifeless universe."

Consider, for example, Newton's discovery that the gravitational force between any two particles is determined by their masses, the distance between them — and the gravitational constant, a number that always stays the same. If the gravitational constant were smaller, that original hydrogen gas would never have been compressed enough to create the temperatures and pressures needed for ignition, and stars would have been dark balls of gas. If it were larger, stars would burn hotter and burn out long before life had had a chance to get started on any planets that might be orbiting them.

Harrison offers nothing less than natural selection of universes. In his words: "Intelligent life in parent universes creates offspring universes, and in the offspring universes fit for inhabitation, new life evolves to a high level of intelligence and creates further universes. Universes unfit for inhabitation lack intelligent life and cannot reproduce."

Just as in biological evolution, small changes in the fundamental constants can occur in the course of reproduction. They may be random, as in Darwinian evolution, or programmed, as in genetic engineering. The next generation, therefore, will be more or less fit to become the home of intelligent life.

Harrison notes that human intelligence has come a long way in the past million years and wonders how much further we will get in the next million. By then, perhaps, we will be smart enough to create universes for ourselves. It may not take that long. Early in the history of our own universe, some postulate, there was a period of extraordinary expansion called inflation. MIT's Edward Farhi and Alan Guth and the University of Mexico's Jemal Guven may have worked out a way to use inflation to make a universe right in the laboratory. Here is their recipe:

Form a small black hole from matter with a mass of, say, 10 kilograms (22 pounds) in such a way that the interior "immediately inflates," Harrison summarizes, "not in our universe, but in a reentrant bubble-like spacetime that is connected to our universe via the umbilical cord of the black hole." (Don't ask.) The black hole will then evaporate, severing the connection between our universe and the new one. Don't worry if you make a mess of it, Harrison advises: poorly made ones will probably never have life in them.

Even if you could make a universe, why would you? Harrison offers three reasons, in ascending order of importance to ourselves. First, only doing it will prove that you really do know how. Second, you may be able to build one that is even more hospitable to intelligence than this one. Third, you may be able to move into the new universes you create. This last could be important for our survival, as we shall see.

Other universes may already be out there. The brave souls who study quantum mechanics talk blithely of alternate universes. They suggest that every time any person or thing does something, a new universe springs into being. There is the familiar one in which the event happened, and a new one in which it did not. Theoretical physicists speak of an infinite number of parallel universes stacked like sheets of paper in a ream, separate worlds in which the very laws of physics themselves could be different. (Another analogy is a huge conglomeration of soap bubbles floating in the air, with each bubble a separate universe. By some strange coincidence, this is the way galaxies appear to be spaced in our universe.) For a long time, the theorists have wondered if it might be possible to use "wormholes" to travel quickly from one part of our universe to another part, or from our universe to another universe (Smithsonian, November 1977). The idea has become familiar from science fiction, especially in the television series Star Trek: Deep Space Nine, in which the plot centers around a space station positioned at one entrance to a wormhole.

Kip S. Thorne, the Feynman Professor of Theoretical Physics at CalTech, has been thinking about wormholes for a long time. The subtitle of his latest book, Black Holes & Time Warps: Einstein's Outrageous Legacy, captures the reaction of most physicists — and ordinary readers--to such ideas. In one chapter, he asks whether a sufficiently advanced civilization will be able to construct wormholes from one part of our universe to another to facilitate rapid interstellar travel. He answers that it possibly could be done by taking advantage of gravitational vacuum fluctuations. These are defined as "random, probabilistic fluctuations in the curvature of space caused by a tug-of-war in which adjacent regions of space are continually stealing energy from each other and then giving it back."


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