What is the ultimate fate of the universe?

Cosmologists constantly argue about this question; although, there is consensus developing that could be the answer we’ve all been waiting on. Not really, but it makes for suspense, albeit future suspense.

Actually, there are only three possibilities, and all of them assume that the Big Bang happened and that the universe is expanding. By this, I mean that space is expanding. The three main assumptions are that the universe is: Closed, Open or Flat. Which one you choose determines the fate of the universe. The truth is that the fate of the universe also depends upon the total amount of dark matter, the Density Parameter, and the value of the cosmological constant.

We’ll start with the cosmological constant. Einstein came up with this when he formulated his theory of general relativity. It’s the value of the energy density of the universe. He came up with this because he thought that the universe was in a static state. In other words, it wasn’t expanding or contracting, but that idea was blown apart when Hubble proved that the galaxies were moving away from one another and that the universe was expanding.

The Density Parameter was a better way to look at this question. This parameter is a ratio that is the average matter density dived by the critical value of that density, sort of like a measure of the shape of the universe expressed by a number. This ratio could be equal to, less than or greater than 1, and the answer tells us if the universe is flat, open or a closed system. This is actually a geometrical concept and it has been assigned the symbol Omega.

If Omega is equal to 1 then the universe is flat and it means that the universe will expand forever at a decelerating rate, but it will continue to expand nonetheless into what is known as the Big Freeze.

If Omega is less than 1 then the universe is open and negatively curved like the surface of a saddle and it means that the universe will expand forever and this expansion accelerates into what is known as the Big Rip where even atoms are ripped apart..

If Omega is greater than 1 then the universe is closed and shaped like a sphere and this means that it will slow down and contract again into what is known as the Big Crunch.

The Big Crunch would have the universe contract into a singularity or what the Big Bang was before it happened.

The Big Freeze would have all of the stars burn out and move away from one another to the point where there would be only minimal energy near absolute zero.

All of these end-of-universe concepts are based on theory. Nothing can be proved with any certainty because we can’t weigh the universe. There isn’t a scale large enough. The only thing we know for sure right now is that the universe is expanding and this expansion is accelerating. This is a recent discovery and it took cosmologists by surprise.

The other thing to keep in mind about this is that any end-of-universe scenario will not happen for trillions of years, which is long after the Earth is gone; so don’t lose any sleep over it. We have plenty of time, unless a large asteroid wipes us out. That worries me more than what will ultimately happen to the universe, and the only reason I’m concerned is the fate of my children and grandchildren, not me.

Thanks for reading.