Our universe has been in existence for nearly 14 billion years and science has led us to believe it will keep existing for many billions more. So, will the universe expand forever, or will it one day collapse under the influence of its own gravity?
According to a new study, our galaxy, other galaxies and the whole universe will collapse completely soon, that is, soon in astronomical terms, which means within the next tens of billions of years. The Universe will continue expanding, then stop and start collapsing in on itself, eventually destroying itself completely.
Nemanja Kaloper at the University of California, Davis, and Antonio Padilla at the University of Nottingham have proposed the mechanism by which universe will meet with its catastrophic collapse in a paper published in Physical Review Letters.
The theory, known as the Big Crunch, has it roots back to dark energy, which accounts for about 75 percent of the mass of the universe. Dark energy acts in opposition to gravity, and as a result is causing the universe’s expansion to accelerate at such a fast pace that it could altogether collapse on itself.
“The fact that we are seeing dark energy now could be taken as an indication of impending doom, and we are trying to look at the data to put some figures on the end date,” said Davis. “Early indications suggest the collapse will kick in a few tens of billions of years, but we have yet to properly verify this.”
The proposed mechanism of the collapse, the researchers believe, can also help answer some questions, which include the cosmological constant problem, which is a value of uniform energy density that fills space. The cosmological constant was introduced by Albert Einstein in 1917 to explain that the universe was not collapsing.
“I think we have opened up a brand new approach to what some have described as ‘the mother of all physics problems,’ namely the cosmological constant problem,” said Padilla.
However, in 1998, scientists revealed that the expansion rate of the universe had accelerated, which resulted in the cosmological constant to yield a non-zero value. Many researchers also believed that the accelerated expansion was also an indication of a collapse.
For the moment, the universe is expanding and has been doing so for the past 13.8 billion years. But according to the latest research, the scientists say their theory suggests before a collapse there will be a period of ‘slow roll’ that brings about the accelerated expansion seen today. Eventually the universe will stop expanding and reach a critical point at which it begins shrinks, causing a ‘big crunch’, the opposite of the Big Bang.
“There is much to do,” Padilla said. “Over the longer term, we would like to understand how our theory could emerge from a more fundamental theory, such as string theory. It is also important to ask what happens when we consider vacuum energy corrections from quantum gravity.”
“The present epoch of acceleration may be evidence of impending doom. . . A detailed analysis to better quantify these predictions is certainly warranted.”