Physicists Nemanja Kaloper at the University of California Davis and Antonio Padilla at the University of Nottingham proposed the “imminent” collapse – which on the cosmological scale is a few tens of billions of years from today, Phys.org reports. Their paper published in Physical Review Letters focuses on the “dark energy” causing the constant expansion of the universe that is predicted to ultimately continue on a path toward collapse.
The researchers sought to answer the massive physics quandary of why the universe is expanding at an accelerated rate and to identify what the dark energy is causing the acceleration.
“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,” Padilla told Phys.org. “It’s way too early to say if it will stand the test of time, but so far it has stood up to scrutiny, and it does seem to address the issue of vacuum energy contributions from the standard model, and how they gravitate.”
The “cosmological constant problem” is that the predicted vacuum energy density expanding the universe is far greater than what is observed. Previous research on vacuum energy predicts the universe will collapse – but physicists are looking to pinpoint what specific mechanism will trigger the “slow roll” collapse.
According to Phys.org, the new mechanism proposes that “the universe originated under a set of specific initial conditions so that it naturally evolved to its present state of acceleration and will continue on a path toward collapse. In this scenario, once the collapse trigger begins to dominate, it does so in a period of “slow roll” that brings about the accelerated expansion we see today.”
The approximately 13.8 billion-year-old universe will ultimately cease its expansion and hit a turnaround point in which it will begin a sloped shrinking that ends in a “big crunch.”
“The ‘technically natural’ size of the slope controls when the collapse trigger begins to dominate, but was it guaranteed to give us slow roll and therefore the accelerated expansion?” Padilla said. “Naively one might have expected to have to fine-tune some initial conditions to guarantee this, but remarkably that is not the case. The dynamics of vacuum energy sequestering guarantee the slow roll.”
The researchers say “there is much to do” still in identifying the specific mechanism which will cause the universe to stop expanding and begin shrinking. The researcher paper concludes that “the present epoch of acceleration may be evidence of impending doom. . . A detailed analysis to better quantify these predictions is certainly warranted.”