Several years ago, Renata Kallosh and Andrei Linde took a vacation to Bora Bora. One night, the husband-and-wife physics professors went for a walk on the beach.
“Suddenly we were looking at the sky, and something was very wrong,” Kallosh recalls. It took her a minute to realize why: she was in the Southern Hemisphere. “It wasn’t the sky we see in Moscow or Geneva or at Stanford.”
For Linde, there was another difference. “The stars were shining, and looking at the sky was exciting, but somehow it was too small,” he says. “What is inside our mental vision is so much greater than what our eye can see.”
Spoken like a true cosmologist. That’s an appellation coming to encompass more and more theoretical physicists, including Kallosh. Instead of ruminating about black holes, the curvature of space and high-energy collisions, many physicists-turned-cosmologists are looking at data from telescopes and satellites and developing computer models of the biggest picture of all: the future of the universe. Which, Linde and Kallosh believe, is short. A mere 10 billion to 20 billion years, give or take.
At 5 p.m. every day, the two sit down at their computers and check out the latest publications in high-energy physics and astrophysics. Over dinner they often confer about their readings—something that would have been impossible when their sons, Dimitri, MS ’00, and Alex, ’00, were growing up and demonstrating their own versions of universal chaos.
The Stanford couple can barely contain their excitement as they talk about findings that are due to be released on January 3, when researchers at Princeton will announce their latest satellite measurements of cosmic microwave background radiation—CMB, as it’s called in the cosmology biz. It may sound like something out of Star Trek, but CMB’s distant glow is what Linde calls “remnants of the primordial cosmic fire” of the birth of the universe.
Linde and Kallosh are hoping the Princeton results will support a new model of the universe that they proposed in August. In the past, most physicists believed the universe would continue to expand exponentially and indefinitely. But in recent years, many scientists have concluded that the universe will die a slow—we’re talking 100 trillion years—cold death. Now, Linde and Kallosh have calculated that there is more “dark energy”—a mysterious, vacuumlike force—than physicists previously recognized. Based on that, they predict that the 14-billion-year-old universe will slow its acceleration, pause and then collapse—ending in a “big crunch” in 10 billion to 20 billion years. To confirm the theory, “we need to have much better instruments and much longer studies,” Linde says.
The Russian-born pair, who worked together at Moscow’s Lebedev Physics Institute before joining the Stanford faculty in 1990, have been searching for a model that takes into account the sometimes-embraced, sometimes-questioned “cosmological constant” that Einstein used in his equations to signify the invisible energy in the vacuum of space. He publicly retreated from it in the 1920s when astronomer Edwin Hubble showed that galaxies were moving away from one another and, consequently, that the universe was expanding. But the cosmological constant, or what scientists now call dark energy, kept appearing in Einstein’s work.
Linde already has revolutionized his field by helping to develop the concept of “inflationary cosmology.” He will receive the Dirac Medal for theoretical physics this summer, along with physicists Alan Guth of the Massachusetts Institute of Technology and Paul Steinhardt of Princeton, for conceiving of the universe beginning not with one Big Bang, but expanding in billionths of a second, in a never-ending chain reaction. In 1986 he refined that theory, suggesting that our universe is one among many that constantly self-reproduce. For now, anyway.
If Linde and Kallosh’s new theory is correct, “then we are somewhere in the middle age of the universe now,” Linde says. “We are living happily in a minuscule portion of time, and just as we are enjoying life more and thinking more, then we have to prepare ourselves for inescapable death.”
But how can we care about an event—granted, it’s universal—that won’t happen for at least 10 billion years?
“This is emotionally important for people to know,” Linde says. “Just like it’s important for us to know what is birth and what is death. This is almost a religious question.”
Kallosh nods in agreement, then adds a collegial proviso. “If our version is realized.”
