There are five possible ways the universe could end.

Is there a time limit on how long the universe can last? In the event that this is the case, how? When will this happen? Although it may be difficult to envisage a catastrophic event that would affect all of existence at once, scientists believe that the end of the universe is inevitable. Here are a few of the more popular theories for how and when the universe might come to an end.

The beginning of the universe is where scientists hunt for clues about the end of the universe. The Big Bang occurred about 13.8 billion years ago, when space and time emerged from an extremely dense singularity. With all the galaxies and the stars and planets they contain, matter cooled and condensed swiftly after that.

This Could be the End of Everything

A unexplained force known as “dark energy” is accelerating the expansion of the cosmos, while the universe continues to grow. Even though we have no idea how this force works or why it’s pushing everything away from each other, it has significant consequences for the course of the cosmos. It all relies on how you change the model’s numbers.

A Severe Cold Snap

The Big Freeze is the most plausible scenario in our best models of the evolution of the cosmos. Calculations estimate the universe will die slowly for a googol years if dark energy keeps expanding at its current rate, which is what we’re seeing now. The unfathomable number begins with a one and ends with 100 zeros.

The stars would become red and eventually disappear if you could fast-forward through billions of years in the sky. Due to the expanding cosmos, the wavelength of their light would gradually shift towards the red end of the spectrum, eventually making it impossible to see them with the naked eye.

For the next several trillion years, even if you couldn’t see the distant stars and galaxies, they would still be there for all eternity. When the expansion continues for a long period of time, it will dilute the dust and gas in space, making it impossible for new stars to form. This eventually leads to a species extinction, since there are no new stars being formed.

The universe’s “Degenerate Era,” which begins roughly 100 trillion years from now, has begun. Only white dwarfs, neutron stars, and black holes remain in the universe at this point, but even they will vanish over time. White dwarfs and some neutron stars will slowly cool into lifeless black dwarfs, while other neutron stars will collide into black holes.

There will be nothing left but black holes in the universe after the year 10 tredecillion (a one followed by 43 zeroes). Stephen Hawking predicted that black holes will eventually vanish, and he was right: they do.

As soon as all the black holes have been extinguished, the cosmos enters its ultimate phase – the Dark Era – which lasts approximately 1 googol years. All that is left are the loneliest of lives for the surviving free particles, who will never get within a light-year of each other, much less interact. And there will be nothing else for all of time.

The Riptide

Death occurs considerably more quickly and dramatically in the same scenario. According to the Big Rip model, dark energy accelerates the expansion of the universe rapidly, ultimately tearing apart the very fabric of reality.

Even if you had the most powerful telescope, there is a physical limit to the distance into space that mankind could ever view. The speed of light sets this boundary; at a certain distance, no more time is available for an object’s light to travel to Earth. The observable universe is the name given to this portion of the cosmos.

Expansion in the Big Rip model drives ever more objects beyond this boundary as it expands exponentially, resulting in an ever-shrinking visible cosmos. They can no longer influence each other through fundamental forces like gravity or electromagnetic if they are further apart than this threshold.

Eventually, gravity’s grip on the universe will be too weak to hold galaxy clusters together, and they will begin to dissolve as the distance between them decreases. A similar process will eventually take place in galaxies, with stars being sent out into the cosmos. Planets will no longer be locked to their orbits around stars when the cosmic event horizon shrinks beyond the scale of an individual star system.

The event horizon would shrink to the size of molecules in the final moments of existence, causing the forces that hold things together to be disrupted, resulting in the destruction of stars, planets, and everything on them. As a last step, the atoms themselves would be shattered into smaller and smaller pieces. The fabric of spacetime itself is the final victim.

If this concept is correct, the cosmos has around 22 billion years left to live, according to the scientists who propose it. In the end, this scenario is less likely to come to fruition than some of the others on this list because other experts believe it includes unrealistic conditions.

The Great Crash

Instead of expanding into nothingness, it may shift course and collapse into a so-called “Big Crunch,” in which everything comes to an end.

To win the cosmic tug of war between gravity and dark energy, scientists typically stack their chips in favour of dark energy, resulting in either a Big Freeze or Big Rip. But we can’t rule out the possibility that gravity could play a role.

The expansion of the universe could be halted if the density of matter in the universe is sufficiently great, resulting in a contraction phase. Once again, as space constricts, everything will begin to move toward everything else. Unlike our current expansion phase, no one would be immediately harmed until the very end.

The merging of galaxy clusters would be followed by the merging of galaxies, and finally by the merging of individual stars. It’s the cosmic microwave background, the radiation left behind from the Big Bang, that’s the main problem.

This radiation heats up to the point where it is hotter than stars when its photons are moved towards the blue end of the spectrum. Stars will continue to get hotter and hotter until they evaporate because they can no longer radiate heat out.

In the last few minutes of the universe’s existence, the temperature would be so high that atoms would disintegrate. They won’t have to worry about that for long, as the universe’s ever-shrinking population of black holes is snatching them up.

A singularity, like a reversal of the Big Bang, will eventually bring together all of the universe’s matter into a single point.

The onset of this contraction phase has been predicted by several scientists at various times. I don’t know how long it will take. There’s another possibility, according to a recent study, that the cosmos will begin to reverse course roughly 100 million years from now. A billion years later, we would be back at that singularity in that model.

It’s Time to Jump!

However, it’s possible that’s not the end. Quantum processes may be able to prevent a collapse of the cosmos into an indefinitely dense singularity, allowing for a fresh Big Bang to begin for the universe. There is a name for this design: the Big Bounce.

According to those who support the theory, there is precedent in quantum physics — after all, as the universe shrinks near the singularity, quantum rules take precedence over the large-scale classical principles we are used to.

It is at this stage that quantum tunnelling can take place, in which particles can break through barriers that they should be unable to do so. Radioactive decay is one example of this driving force. A new study also suggests that a contracting universe could “escape” the doom of ultimate collapse and begin growing again.

According to another hypothesis, loop quantum gravity, the Big Bounce can be explained using quantum mechanics. This is interesting, because the Big Bounce is based on this theory.

Big Bounce hypotheses have the amusing implication that our world is part of a never-ending cascade of universes being produced and destroyed.

In the Big Slurp

Possibly the scariest scenario on this list is the one in which we don’t know what’s going to happen until it’s too late. False vacuum decay, or the Big Slurp, is the more common moniker for this phenomenon.

Physics dictates that a system will always strive to achieve equilibrium. It does this by descending in energy from a high to a low state until it reaches its lowest possible state. This is known as the vacuum state for quantum fields.

Except for the Higgs field, all known quantum fields are believed to be in their stable vacuum states. Currently, it appears to be stable, however it is projected to not be at its lowest energy level.

However, anything might happen at any time. In a split second, the Higgs field might collapse, destroying a large portion of our universe and leaving us with nothing but empty space.

The vacuum decay bubble would spread outward at the speed of light if only one point in space collapsed into this lower energy state. We didn’t even notice it was coming until the wall of the bubble smacked onto the Earth’s surface.

Once we’ve entered this protective bubble, what will happen? The rules of nature may be rewritten as a result, but no one knows for sure. A new theory of physics may allow for life, but the cosmos may be so different that we cannot even begin to imagine it. Ultimately, the worst-case scenario results in the total destruction of all matter.

There is some good news in that there is a great deal of ambiguity surrounding the idea. False vacuum decay may not occur for many billions of years, or it may be impossible. The bubble’s weird new physics should have occurred by now, according to some, implying that our current universe may truly be a manifestation of it.

It’s also possible that the Higgs field is more stable than we think. After all, the existence of the Higgs boson was just recently established, indicating that there is still plenty to learn through additional research.

It’s also possible that the Sun has just been swallowed by a false vacuum bubble, in which case we’ll arrive in eight minutes.