In March, 1981, I watched a Doctor Who episode called “Logopolis.” I was eight years old and it terrified me. This is probably unsurprising to anyone who grew up with the classic show…or watched “Blink.” “Logopolis”( had three scary things going for it; it was Tom Baker’s last episode, so the Doctor “died,” the Master was going around turning people into little dolls (Something I was glad to see come back last series) and…
…and it was the thing which introduced me to the ultimate “mortality.” The universe was going to end.
Is going to end.
The regeneration was sad, but I suspect most people were scared of the little dolls. To my eight-year-old self, though, the idea that the world had not always existed and would not always exist?
I had an existential crisis and repressed the episode from my memory until I was ready to face it again as an adult. (It’s not, objectively, as scary as “Blink.”).
But part of me’s still not one hundred percent ready to face the death of the universe. Thankfully, it’s still a long, long time in the future. And we still aren’t entirely sure how it will happen. There are three main theories. Let’s go through them.
The Big Crunch
The Big Crunch is based on a simple theory: We live in a so-called “closed” universe. Because of the amount of matter, the universe is not capable of expanding forever and will at some point hit its limit.
At that point, the universe will start contracting again. Eventually, stars and galaxies will start crashing into each other and the entire universe will sink down into a single point.
Some scientists think that if that happens, it will explode again (the cyclical universe theory or the Big Bounce). For this reason I’ve always found it the most hopeful of the scenarios. Unfortunately, it’s also the most unlikely. Why?
We most likely live in an “open” universe, in which space-time can just keep right on expanding forever.
The Big Freeze
This is the current theory. The universe will keep right on expanding forever, and entropy will have its way. As stars get further and further apart, the kinds of collisions and events that birth new stars will become rarer and rarer. Light will no longer be able to cross the universe and it will become dark.
Eventually all the stars will die and the universe will become a dormant expanse that just kind of sits there. Forever.
The Big Rip
The expansion of the universe is not steady. Because of this, some scientists theorize that expansion will speed up until the acceleration exceeds all the forces keeping the universe together.
At that point, the universe will literally tear itself apart, everything will disintegrate into elementary particles and the end state will resemble a very large singularity.
Uh, even more bleak.
The good news is that none of these things will happen for a long, long time. Trillions of years.
Then there‘s the even worse one, which is a very minority view but not impossible.
The Big Slurp
Okay, not yum. The concept of this is that the universe is not actually in the lowest energy state. This means that what we think of as vacuum is in fact a false vacuum. While a true vacuum is stable essentially forever, a false vacuum is, well, not.
This could result in vacuum decay, where some part of the universe collapses to a different level of vacuum. This would expand outwards as a true vacuum bubble, likely destroying everything in its past. Or it would collapse inward and pull the entire universe with it.
Oh, and in the bubble, life and chemistry as we know it would cease to exist, although it’s possible some form of life might eventually develop.
Thankfully, even this is pretty unlikely to happen, although if it did it could happen tomorrow. Or already have happened in some reach of the universe we can’t see.
I try not to think about this one (especially as it maps to the end of the universe scenario the Doctor has to prevent in “Logopolis,” although it wasn’t science then).
Will Anything Exist After the Universe?
So, if all of this is making you feel a little cold, how about the question of existence after (and for that matter before) the universe?
If the Big Bounce happens, then the answer to what exists after the universe is another universe. That would also likely be the answer to what existed before the universe.
In any other scenario, then the obvious answer is “nothing.”
But there’s another scenario, in which the answer is “All the other universes.” Multiple universes has not been proven, but many experts think that there are indeed more universes out there. Perhaps they were all born out of the same Big Bang. Perhaps not.
If that’s the case then we can assume that somewhere out there in some other universe there will still be conscious beings.
Or, of course, we can just stop worrying about it and live our lives on this little planet in this little corner of this very big universe.