Troubling though it may be, the turmoil in our present universe can’t match the “end of time” scenario painted in a newly published paper by scientists at Caltech and Dartmouth. The universe will end not with a whimper or even a bang, they predict, but in a “big rip” that will make the most pyrotechnical “Star Wars” sequence seem tame.
Unless the dust of war takes 22 billion years to settle, the big rip is not the most pressing danger facing humankind. However, since its February publication, the theory has been challenging comfortable orthodoxies in cosmology and influencing science funding action in Washington.
Conventional wisdom about the ultimate fate of the universe changed little between 1929, when astronomer Edward Hubble calculated that the universe was expanding, and 1998, when an international team of scientists, led by Adam Riess, then a young astronomer at UC Berkeley, theorized that the expansion was being accelerated by a mysterious anti-gravitational force called dark energy.
On Jan. 25, Gia Dvali at New York University and Michael Turner of the University of Chicago challenged Riess with a study suggesting that dark energy was a figment of his imagination. The universe is falling apart, they argue, not because of some phantom force but because the power of gravity diminishes over long distances.
But one month later, in the Caltech- Dartmouth paper, published in the online journal Physical Review, Marc Kamionkowski, Nevin Weinberg and Robert Caldwell argued that dark energy was not only real but growing more powerful. In about 22 billion years, they estimate, it will be strong enough to rip all structures apart, starting with galaxies and moving to stars, planets and atoms.
Astronomers’ best bet for figuring out who’s right is the Supernova Acceleration Probe, or SNAP, a satellite with a camera 30 times larger than that of the Hubble Space Telescope. In recent weeks, Energy Secretary Spencer Abraham and his deputies have twice asked Congress to accelerate funding for the University of California- designed probe, which will determine whether dark energy exists by measuring the precise expansion rates of huge supernovae. Because each new image from Hubble and its space probe brethren seems to upset some theory of 20th century physics, there is an admirable perverseness in scientists persuading Congress to fund SNAP, ensuring more cosmic headaches.
The universe may eventually end in a doom of fire or ice. In the meantime, scientists’ willingness to risk migraines for ultimate knowledge suggests that cosmology has a bright future.