How Will The Universe End? - Researchers theorize on whether the cosmos will end in fire, ice or something else. Cosmology deals with the big questions of the universe, often the same questions that keep philosophers up at night. When did the universe begin? How did it start? Has the universe always been expanding? (For the record, the answers are: about 13.8 billion years ago, in a high-density state that rapidly expanded called the Big Bang and yes, but not always at the same speed.) But here’s a question they haven’t figured out yet: How’s it all going to end? It’s a big question all right, but we’ve made surprising headway toward an answer. In the last years of the 20th century, the astrophysical community was stunned to learn that the universe was driving itself apart. For decades, scientists had known that distant galaxies all move away from us, with the farther ones moving the fastest. The only way this makes sense is if the universe itself is expanding. Given all the matter in the cosmos, the force of gravity should be slowing down that expansion. But when cosmologists calculated just how much it’s slowed down, they got a negative result — the expansion of the universe is speeding up! Nobody knows what’s driving the acceleration, so cosmologists have dubbed that mystery dark energy. It is so dominant (about 69 percent the total content of the entire cosmos) that dark energy quickly became a part of any discussions about the final end of the universe. And while there are no definite answers yet, those discussions have come up with a few interesting possibilities. The Big Rip No one knows what dark energy is, so we can’t be sure how it will behave in the future. In 2003, Robert Caldwell of Dartmouth College proposed a new theory of the expansion of the universe where the rate of acceleration keeps increasing over time. Imagine a driver who keeps a foot on the gas pedal of a car with no top acceleration. As the car goes faster and faster — the speed of the velocity change itself increasing over time — the car would eventually fly apart in pieces as friction took its toll. A similar thing happens to a universe with relentless acceleration: Galaxies would be destroyed, the solar system would unbind and eventually all the planets would burst asunder as the rapid expansion of space rips apart its very atoms. Finally, our universe would end in an explosion, a singularity of literally infinite energy. Current theories predict that if this so-called Big Rip is in our future, it will take another 22 billion years to arrive. But there are still many details to fill in, and scientists like Vanderbilt University mathematician Marcelo Disconzi will provide those details. His work originally focused on bulk viscosity — the measurement of a fluid’s resistance to expansion or contraction — and how moving fluids behave when approaching the speed of light.
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