All good things must come to an end – and the universe in which we reside is no exception. In a few billion years from now, the Sun will swallow our Earth; and anywhere from millions to trillions of years later, the entire universe will face a catastrophic fate as well, according to the article “The end of everything: 5 ways the universe could be destroyed” from New Atlas writer Michael Irving.

There is a lot of mystery surrounding the universe – no one knows for certain if the universe is finite, or if it is shaped in a sphere, or if it even has a shape at all because it goes on infinitely. And no one has definitively predicted the death of the universe. However, human knowledge has not prevented human imagination from theorizing the possible ways our universe could end. With that in mind, here are some of the most interesting – ahem, horrible – ways in which our good thing could come to an end.

The Big Freeze:

The universe is expanding – this is something scientists are certain of. Dark energy, a hypothetical form of energy acting as an anti-gravitational force, has been blamed for the universe’s continuous expansion; it is said to “make up some 69 percent of the universe’s mass,” according to Eric Betz in his article “The Big Freeze: How the universe will die.” In this first scenario, the universe continues to expand forever. Entropy, the law that says everything naturally decays, will overrule the universe in that planets will collide, stars will die and form black holes, and black holes (in almost a hundred trillion years) will begin to evaporate in the form of Hawking radiation. At the “end,” so to speak, the universe will reach its final temperature of just above absolute zero, as Irving claims. The universe’s death, in this case, is drawn out over a googol of years, a one followed by 100 zeroes.

The Big Rip:

I could make a hundred jokes about the name of this one, but I fear I would blow you away with my humor. No takers? Okay then, let me continue.

In this scenario, dark energy fuels the expansion of the universe at an exponential rate. Gravity, the force that holds everything in our universe together, begins to lose its influence over all matter. Planets break off their orbits; stars drift; galaxies start to dissolve. In about 22 billion years, the end stage will be reached – the forces that hold the smallest molecules together will lose their hold, and finally all molecules themselves will be torn apart, believes Irving. According to Paul Sutter’s article “What is the big rip, and can we stop it?” many physicists deem this scenario implausible; one of the smallest theorized subatomic particles, quarks, “…cannot be torn apart… [since] you need so much energy that new quarks materialize out of the vacuum.”

Whether or not this could happen, at least this version of the death of the universe probably won’t smell as bad as it sounds.

The Big Crunch:

Dark energy, according to NASA, is everywhere and all around us; we don’t notice it, however, because gravity is much stronger and able to counteract dark energy’s effects. However, on an intergalactic scale, “… dark energy becomes noticeable…” as per NASA’s explanation of dark energy. In this scenario, gravity continues to be much stronger than dark energy, even at an intergalactic measure. Irving claims that in about 100 million to billions of years in the future, the universe’s expansion will cease and gravity will take the reins. And then, the boundaries of the universe will contract, and the expansion will “reverse.” Galaxies will begin to merge, and other heavenly bodies will begin to collide more often. The cosmic microwave background will also begin to heat up the universe to temperatures that exceed those of the stars, leading them to evaporate. Black holes will continue to dominate the shrinking universe, and eventually the universe will be condensed into one “ impossibly tiny space – a singularity, like a reverse Big Bang.”

The Big Bounce:

This scenario is a deviation from the Big Crunch – according to Irving, at the last moment of the universe’s life, when its size is an infinitesimally small point, “quantum processes” cause the universe to change course again and expand, as it happened in the Big Bang. In a singularity, gravitational forces are so intensely focused on such an infinitely small point that classical physics no longer applies and we must rely on quantum physics. Irving writes, “The fun implication of the Big Bounce hypothesis is that we might be in the middle of a never-ending chain of universes being created and destroyed.”