We all had been told that we live in a Universe that’s engaged in an everlasting expansion. What’s causing the Cosmos to expand is, first of all, the Big Bang itself. Since that very moment that occurred 13.7 billion years ago, our Universe began to expand from an incredibly small point where there was all the matter we see today.
Once scientists found out that the Universe is expanding, roughly a century ago after the observations of the great American astronomer Edwin Hubble, they realized that it’s just a matter of time until it will slow down and eventually collapse in its own gravity. That process could start billions of years from now, but the astronomers were stunned to discover that there’s also a mysterious structure out there, much more prevalent than usual matter, that accelerates the expansion of the Universe itself. They called it ‘dark energy’, and nobody knows exactly what it is even today.
New theory proposes something different
Some textbooks might have to be rewritten. A new theory proposes that the role of dark energy in the Universe’s expansion will lessen over time. This obviously contradicts the everlasting expansion scenario, and instead, it proposes a model where the Universe will start contracting at some point.
But when will the latter scenario might start occurring? Cosmin Andrei from Princeton University together with other scientists, try to bring a compelling answer. After analyzing the possibility using theoretical models that are aligned with current observations, they believe that the Universe could stop expanding sooner than expected: perhaps ‘only’ millions of years rather than billions.
Scientists believe that the properties of dark energy could change enough to still remain consistent with our Universe as it’s currently being observed. They further calculated the minimum amount of time needed before the transitions could start.
In one scenario, the researchers’ calculations indicate that “the time interval remaining before the end of acceleration is less than the time since the Chicxulub asteroid brought an end to the dinosaurs.” That means roughly 65 million years.
Why exactly did the expansion of the Universe start in the first place? Why were all the matter, time, and space once cramped into that incredibly small singularity? Finding answers to these questions represents major challenges in science even today.