The universe, it is possible, may end neither with a bang nor a whimper, but with a rip.
According to a new study now available online on the preprint server arXiv.org, dark energy — the mysterious force that scientists believe makes up nearly 70 percent of the universe and is responsible for its accelerated expansion — may eventually cause the cosmos to gradually tear itself apart, down to the atomic level.
As things stand now, scientists believe the most likely scenario of the universe’s death is the “Big Freeze.” This hypothesis invokes the second law of thermodynamics to argue that in the distant future, after the last stars have died out, the universe will suffer a “heat death,” and would become a high-entropy wasteland strewn with useless energy.
The new study, however, paints a different picture of the universe’s demise. According to it, it is entirely possible that hitherto undetected changes in the nature of dark energy may cause the universe to tear itself apart.
“We don’t know of anything that behaves this way,” David Spergel from Princeton University in New Jersey, who wasn’t involved in the study, told New Scientist. “But that doesn’t mean it can’t happen.”
In the study, the researchers examined three possible ways in which this cataclysmic event may take place — the big rip, wherein the fabric of space-time abruptly rips itself to shreds at a fixed point in the future, the little sibling of the big rip, and the little rip. The latter two are scenarios in which the tear takes place gradually, rather than at a fixed point in the distant future.
“What they have in common is that our galaxy, and all galaxies, would be ripped apart,” co-author Mariam Bouhmadi-López from the Technical University of Lisbon in Portugal, told New Scientist. “Everything goes wrong.”
In order to understand which of these events has the greatest chance of occurring, the researchers studied the latest map of the cosmos created using observations from the Wilkinson Microwave Anisotropy Probe and the Planck satellite. By analyzing the differences in the distribution of dark energy, they came to the conclusion that the little rip is the most likely scenario — one that would slowly “unzip” the universe roughly 100 billion years from now.