Physics & Math / Cosmology

The universe is out of control. Not only is it expanding but the expansion itself is accelerating. Most likely, such expansion can end only one way: in stillness and total darkness, with temperatures near absolute zero, conditions utterly inhospitable to life. That became evident in 1998, when astronomers at the Lawrence Berkeley National Laboratory and Australian National University were analyzing extremely distant, and thus ancient, Type Ia supernova explosions to measure their rate of motion away from us. (Type Ia supernovas are roughly the same throughout the universe, so they provide an ideal “standard candle” by which to measure the rate of expansion of the universe.)

Courtesy of the Canada-France-Hawaii Telescope/J.-C. Cuillandre/Coelum   advertisement | article continues below There’s no time like the present to start planning our cosmic egress. Scenes like this one, of the massive galaxy M87, will become fleeting memories as the universe advances in age. Thanks to dark energy, even the nearby galaxies will begin to recede from us faster than light, and no news of them will reach us. Eventually even the atoms will be too cold to move, and time itself will freeze—too late for any straggling civilization.

Physicists, scrambling to their blackboards, deduced that a “dark energy” of unknown origin must be acting as an antigravitational force, pushing galaxies apart. The more the universe expands, the more dark energy there is to make it expand even faster, ultimately leading to a runaway cosmos. Albert Einstein introduced the idea of dark energy mathematically in 1917 as he further developed his theory of general relativity. More evidence came last year, when data from the Wilkinson Microwave Anisotropy Probe, or WMAP, which analyzes the cosmic radiation left over from the Big Bang, found that dark energy makes up a full 73 percent of everything in the universe. Dark matter makes up 23 percent. The matter we are familiar with—the stuff of planets, stars, and gas clouds—makes up only about 4 percent of the universe.

As the increasing amount of dark energy pushes galaxies apart faster and faster, the universe will become increasingly dark, cold, and lonely. Temperatures will plunge as the remaining energy is spread across more space. The stars will exhaust their nuclear fuel, galaxies will cease to illuminate the heavens, and the universe will be littered with dead dwarf stars, decrepit neutron stars, and black holes. The most advanced civilizations will be reduced to huddling around the last flickering embers of energy—the faint Hawking radiation emitted by black holes. Insofar as intelligence involves the ability to process information, this, too, will fade. Machines, whether cells or hydroelectric dams, extract work from temperature and energy gradients. As cosmic temperatures approach the same ultralow point, those differentials will disappear, bringing all work, energy flow, and information—and the life that depends on them—to a frigid halt. So much for intelligence.

A cold, dark universe is billions, if not trillions, of years in the future. Between now and then, humans will face plenty of other calamities: wars and pestilences, ice ages, asteroid impacts, and the eventual consumption of Earth—in about 5 billion years—as our sun expands into a red giant star. To last until the very end of the universe, an advanced civilization will have to master interstellar travel, spreading far and wide throughout the galaxy and learning to cope with a slowing, cooling, darkening cosmos. Their greatest challenge will be figuring out how to not be here when the universe dies, essentially finding a way to undertake the ultimate journey of fleeing this universe for another.

THINK SMALL Stephen Hawking has suggested that it might be possible to travel through a wormhole to another universe or another time. This may allow an advanced civilization to evade the death of the universe. Even if the wormhole is subatomic it might still be possible to inject enough information through the wormhole via nanotechnology to re-create the entire civilization on the other side.

Such a plan may sound absurd. But there is nothing in physics that forbids such a venture. Einstein’s theory of general relativity allows for the existence of wormholes, sometimes called Einstein-Rosen bridges, that connect parallel universes. Among theoretical and experimental physicists, parallel universes are not science fiction. The notion of the multiverse—that our universe coexists with an infinite number of other universes—has gained ground among working scientists.

The inflationary theory proposed by Alan Guth of MIT, to explain how the universe behaved in the first few trillionths of a second after the Big Bang, has been shown to be consistent with recent data derived from WMAP. Inflation theory postulates that the universe expanded to its current size inconceivably fast at the very beginning of time, and it neatly explains several stubborn cosmological mysteries, including why the universe is both so geometrically flat and so uniform in its distribution of matter and energy. Andrei Linde of Stanford University has taken this idea a step further and proposed that the process of inflation may not have been a singular event—that “parent universes” may bud “baby universes” in a continuous, never-ending cycle. If Linde’s theory is correct, cosmic inflations occur all the time, and new universes are forming even as you read these words.

Naturally, the proposal to eventually flee this universe for another one raises practical questions. To begin with, where exactly would an advanced civilization go?

As it happens, physicists are spending billions of dollars on experiments to probe the nature of parallel universes. Since 1997, scientists at the University of Colorado at Boulder have conducted experiments to search for parallel universes perhaps no more than a millimeter away from ours. The experiments searched for tiny deviations in Newton’s inverse square law of gravity. The surface of a sphere in three dimensions is equal to 4π times the radius squared. Likewise, the surface of a sphere of higher dimensions is proportional to the radius cubed. According to Newton’s law, in such a sphere the measurable gravity should decrease as a factor of the distance cubed. So the Colorado physicists set about measuring the gravity within a small, defined space. If the gravitational force deviated significantly from Newton’s equation (the distance squared) and was more closely proportional to the distance cubed, the research team theorized, that would suggest the presence of a hidden dimension.

Newton’s inverse square law has been tested with exquisite precision by space probes, but it had never been tested at the millimeter level. So far, the results from these experiments have been negative, but other scientists are looking for even smaller deviations. A group at Purdue University has proposed testing Newton’s inverse square law down to the atomic level using nanotechnology.

Physicists elsewhere are exploring other possibilities. In 2007 the Large Hadron Collider, the world’s largest atom smasher, will be turned on outside Geneva, Switzerland. This huge machine, more than five miles in diameter, is capable of blasting protons together with a colossal energy of 14 trillion electron volts; it will be able to probe distances 1/10,000 the size of a proton, perhaps creating a zoo of exotic particles not seen since the Big Bang. One hope is that it will create exotic particles like miniature black holes and sparticles, or supersymmetric particles, which would indicate the presence of parallel universes in higher dimensions.

In addition, the space-based gravity-wave detector LISA (Laser Interferometer Space Antenna) will be launched sometime around 2012. It will consist of three satellites trailing Earth’s orbit around the sun and communicating with one another via laser beams, thereby creating a triangle with sides more than 3 million miles long. LISA is designed to detect faint gravity waves from extremely far away—gravitational shock waves that were emitted less than a trillionth of a second after the instant of creation. The instrument is so sensitive that scientists hope it will be able to test many of the theories that seek to explain what happened before the Big Bang and probe for the existence of universes beyond our own.

To journey safely from this universe to another—to investigate the various options and do some trial runs—an advanced civilization will need to be able to harness energy on a scale that dwarfs anything imaginable by today’s standards.

To grasp the challenge, consider a schema introduced in the 1960s by Russian astrophysicist Nikolai Kardashev that classified civilizations according to their energy consumption. According to his definition, a Type I civilization is planetary: It is able to exploit all the energy falling on its planet from the sun (10¹⁶ watts). This civilization could derive limitless hydrogen from the oceans, perhaps harness the power of volcanoes, and maybe even control the weather. A Type II civilization could control the energy output of the sun itself: 10²⁶ watts, or 10 billion times the power of a Type I civilization. Deriving energy from solar flares and antimatter, Type IIs would be effectively immune to ice ages, meteors, even supernovas. A Type III civilization would be 10 billion times more powerful still, capable of controlling and consuming the output of an entire galaxy (10³⁶ watts). Type IIIs would derive energy by extracting it from billions of stars and black holes. A Type III civilization would be able to manipulate the Planck energy (10¹⁹ billion electron volts), the energy at which space-time becomes foamy and unstable, frothing with tiny wormholes and bubble-size universes. The aliens in Independence Day would qualify as a Type III civilization.

By contrast, ours would qualify as a Type 0 civilization, deriving its energy from dead plants—oil and coal. But we could evolve rapidly. A civilization like ours growing at a modest 1 to 2 percent per year could make the leap to a Type I civilization in a century or so, to a Type II in a few thousand years, and to a Type III in a hundred thousand to a million years. In that time frame, a Type III civilization could colonize the entire galaxy, even if their rockets traveled at less than the speed of light. With the inevitable Big Freeze at least tens of billions of years away, a Type III civilization would have plenty of time to develop and test an escape plan.

Why not start now? On the following pages are experiments and plans to guide a civilization looking for a way out—a survival guide to the end of the cosmos.

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Adapted from the book Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos, published this month by Doubleday. Copyright © 2004 by Michio Kaku.