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Is the Universe Shrinking?

VO: Eric Cohen WRITTEN BY: Nathan Sharp
The Universe is big. Like, really big. But will it ever stop growing and start to get smaller? Some theories say it will, leading to an eventual collapse, bounce back or general descent into nothingness. It all sounds pretty ominous, but it's purely theoretical. For now, at least!

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Will the Universe Ever Shrink?

The universe is a big place, and it’s only getting bigger. Even as you watch this video, space is expanding, and galaxies are reaching further and further away from us. This isn’t because the actual star systems are floating through space, but because the very fabric of space itself is growing. And amazingly, scientists have little-to-no idea why this is.

At the moment, the most popular theory seems to centre on that ever-mysterious intellectual unknown, dark energy. Experts estimate that as much as 68% of the total energy in the entire universe is made up of this mysterious dark energy, although no-one really has any idea what it actually is or what it’s composed of. That it’s responsible for the acceleration of the expansion of space is one of the few things we can be even slightly confident on.

But, while we know that the universe is expanding and has been for the last 14 billion years or so, will it ever shrink? Surely it can’t just keep getting bigger until the end of time– can it? So, will there ever be a moment when everything there ever was withdraws back into itself?

Again, scientists are unsure. The general consensus seems to be – “maybe, but probably not”. Experts agree that there are at least three possible outcomes for the universe. The first and most likely theory is called The Big Freeze, also ominously known as Heat Death. This theory posits that the universe will eventually spread itself so thin that gas and matter won’t be able to gather and unite under gravity, which means no new stars will form. Any type of heat or energy transfer will also be made obsolete, in what’s otherwise known as maximum entropy. This means that space will eventually become an endless and energy-devoid vacuum with nothing in it. What happens to this vacuum of absolute emptiness is anyone’s guess, but what is clear is that planets, stars, galaxies and life will cease to exist.

The second theory is The Big Rip. And this one is completely terrifying. The theory goes that dark energy will eventually become so powerful that it overcomes the force of gravity, and in doing so literally rips the fabric of space apart. The force of dark energy will become so strong, and the force of gravity so inconsequential and minute, that the dark energy will ruthlessly destroy all suns, moons, black holes, and even individual atoms. Nothing will exist because everything will’ve been annihilated. The universe itself would exist, but only as a massive area of pure dark energy, without any other matter whatsoever. Again, it’s impossible to speculate on what a 100% dark energy universe would look like (particularly because we don’t know what dark energy is), but it sounds pretty terrifying, doesn’t it?

The final theory on what will happen to the universe, and the one that most interests us today, is called The Big Crunch. This idea is essentially the exact opposite of The Big Rip. Experts hypothesise that it might be possible for gravity to one day become so strong (or at least that the power of the universe’s expansion will become so weak, by comparison) that it will halt further expansion and begin the process of drawing everything back to a single gravitational point called the singularity. In short, the universe and everything in it would shrink (or retract) from whence it came, through sheer, fundamental force.

The action would centre on all established galaxy systems. As the gravity becomes stronger, galaxy clusters, like the nearby Virgo Cluster, would begin to coalesce and collapse into each other, resulting in complete pandemonium as stars and planets collide causing brilliant explosions. But a collision isn’t even the worst that could happen. The temperature of space itself would eventually increase, meaning the stars wouldn’t be able to release their internal heat. This would result in them eventually cooking themselves to death and exploding in spectacular and chaotic supernovas. Either way, there’d be a lot going on, and the universe would be very brightly lit indeed.

Over time – and these developments could take centuries, millennia or even millions of years of shrinkage to unfold – all matter in the galaxy, including the remains of stars and planets like our own, will eventually merge into massive black holes. These black holes would in turn attract towards each other, to ultimately create one all-encompassing black hole called the singularity. Every iota of matter that ever existed would eventually condense into this spot, and the universe as we know it would cease to exist.

Some experts even believe that this would cause a reverse big bang. According to the theory, the singularity will eventually expel all the matter it had collected during the Big Crunch, sending it back out to create a new life cycle of the universe. So, if this idea is correct, we’re more than likely already living through one of the infinite phases of the universe’s contraction and growth. Perhaps the big bang that bore everything we’ve ever known was simply the result of a previous singularity’s reversal and expulsion. This could be the millionth, or even billionth time that humans have inhabited the universe – as though life is but an unbeatable level on the most complex computer game imaginable. It blows your mind a little, doesn’t it?

But would (and could) the shrink theory actually ever come to pass? While astrological and scientific approaches are always changing (heck, the term “dark energy” wasn’t even invented until 1998), the majority of those in the know tend to agree that a Big Crunch will not happen. There’s growing evidence that the universe is actually accelerating at an even faster pace than previously imagined, showing no signs of ever slowing down, up until this point. Although no-one can know for sure, more clues indicate either a Big Rip or a Big Freeze, with the latter being largely accepted as by far the most likely.

That said, the nature of dark energy is still the big unknown, as we’re almost entirely ignorant of its properties and behavior. It’s possible that dark energy might one day simply disappear or change its properties without warning, resulting in a stronger gravitational pull – amongst all sorts of other apocalyptic immensities – and the eventual end of the universe, shrunken down into a tiny singularity. However, the force of dark energy is seemingly constant, which means it is likely to continue to perform as it has done for an infinite amount of time – which is why the Big Freeze remains the favoured outcome for most experts.

If dark energy increases in strength, we could be headed for the Big Rip. If it weakens, then the Big Crunch – and the universe will shrink. But otherwise, our galaxy and all others are going to get very, very cold. There’s no need to bust out the blankets just yet though; if any of this ever does happen, it won’t be until very, very far into the future.

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