The Universe Might End Sooner Than We Thought – But Don’t Worry, We’ve Still Got 33 Billion Years

The universe began in an event we call the Big Bang around 13.8 billion years ago. Humanity has been able to understand a lot of what has happened since and where the universe is going, but we do not know exactly how it is going to end. A new study suggests that the cosmos might bow out a lot sooner than many others had anticipated: in just 33 billion years.

It all boils down to a mysterious component of the universe called dark energy. This hypothetical substance is responsible for the current accelerated expansion of the cosmos, but depending on its true nature, it might lead to a dramatically different future for everything in the universe.

The universe might expand forever and get colder and colder, eventually reaching heat death. If this scenario is correct, then the universe is going to be around for an enormous number of years (although maybe not as many as we originally thought). But what if the universe doesn’t expand forever? Well, it might then collapse back onto itself in the Big Crunch.

This idea has been around for a long while, but the discovery of the accelerated expansion of the universe has pushed many to consider it less likely to happen. Originally, the Big Crunch scenario saw the universe expanding like ours. After many billions of years, it slows down, until things start coming back together again. Now the universe looks like it is filled with dark energy, acting as a cosmological constant of space-time. This means that the more space-time there is, the more dark energy there is. In that scenario, you never slow down the universe.

We do not know what dark energy is. Most observations find it consistent with the cosmological constant within a certain margin of error, but it might not be. Recently, some observational evidence suggested that it is possible for dark energy to change. If it’s not a constant, things might be different in the future.

A scenario for the nature of this different dark energy was evaluated in a new paper that is currently awaiting peer review. Its authors find its nature to be mixed: part cosmological constant and part the energy of axions, a possible particle that makes up the equally mysterious and hypothetical dark matter. The interesting part is that their model of the cosmological constant is negative. So, despite the current accelerated expansion, the universe will eventually reverse its course.

According to their model, the universe will end in 33.3 billion years in the future, so we have a fair time to go even before experiencing the midpoint of this hypothetical scenario.

There are other ways for the universe to end. Dark energy might be greater than the cosmological constant and rip space-time apart (Big Rip), the Big Bang and Big Crunch would be components of a never-ending repeating cycle (Big Bounce), and my personal favorite, the false vacuum decay, where a random quantum effect could bring back the end of everything without warning.

The paper, which is yet to be peer-reviewed, is posted to arXiv.