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  • We have a pretty good idea of how and when the universe began

  • as for how it's going to end... ummmm

  • Hi everyone, in Universe A, Julian here for DNews.

  • The Big Bang Theory is more than just a TV show my parents keep telling me I should be on.

  • It's our best explanation for how the universe, as we know it, started.

  • When Edwin Hubble looked at the night sky in 1923, he discovered that the universe was much bigger than just our Milky Way.

  • There were actually metric oodles of galaxies, all over the place.

  • Then in 1929, because he wasn't done being a science boss,

  • Hubble also noticed that the majority of galaxies are speeding away from us.

  • Logically, then, if you go backwards in time,

  • everything must have been smushed together in a singularity, at some point,

  • and I mean that both physically and temporally.

  • With all that phenomenal cosmic power in an itty-bitty living space,

  • it blew right up in the greatest fireworks display of the last 13.8 billion years.

  • As you can imagine, this discovery was a game-changer.

  • Einstein's equations on general relativity from 1917

  • should've mathematically predicted an expanding or contracting universe,

  • but the math had been intentionally fudged by a scientist who didn't want to believe the universe wasn't static

  • and what was that name of that idiot who ruined Einstein's math?

  • A man by the name of Albert Einstein.

  • Einstein called his creation of his cosmological constant

  • "The greatest blunder of his career"

  • and as a result, has been doomed to obscurity.

  • So, if the universe has a beginning, then what does that mean for how it will end?

  • Where is this all going?

  • Well that nut's a little tougher to crack.

  • At first, it was thought there was two possibilities.

  • If the universe has enough stuff in it, gravity slows the expansion, and eventually it will collapse into a singularity and maybe even another big bang.

  • This is elegant, and beautiful, and makes wonderful, satisfying sense.

  • Unfortunately, the universe is under no obligation to make sense to you.

  • And the other possibility is happening.

  • The universe isn't just expanding, it's accelerating.

  • What's driving the acceleration? What is making space itself expand like the surface of an inflating balloon?

  • We have no idea.

  • Our best guess is some, as yet, unexplained source of energy snappily known as "dark energy."

  • So, if everything keeps going the way it is, it looks like the universe could expand and exist forever.

  • Whether life can exist forever is a different story.

  • Our sun will exhaust it's fuel in about 5 billion years, while much smaller red dwarfs will use their fuel in trillions of years.

  • That is an incomprehensibly long time, but that time will come nonetheless.

  • Black holes will still be doing stuff; radiating particles back into the void,

  • but even supermassive black holes will dissipate after googols of years.

  • Eventually entropy will spread energy uniformly across the universe and it just won't be possible to do literally anything.

  • So life as we know it, is 'kaput'.

  • This is called the "Heat Death of the universe"

  • or "The Big Freeze"

  • and it looks like we're headed that way.

  • An international team of astronomers just studied the energy output from two hundred thousand galaxies

  • and discovered its half of what it was just two billion years ago.

  • We're apparently in the midst of a steep decline but eventually it will slow down

  • as only the biggest black holes are left petering out.

  • That is one way the universe could end ...

  • not with a bang but a whimper ...

  • but we don't know enough about dark energy to assume it's going to keep acting the way it does.

  • Maybe it'll slow or even reverse and we'll get a big crunch or a cyclical universe

  • or maybe everything, even atoms themselves, will get ripped to shreds.

  • Remember I said dark energy is making space itself expand?

  • Things aren't just moving away from us. Space itself is growing.

  • It stretches at about 70.4 kilometers per second per megaparsec

  • which means that if you had two objects a megaparsec apart with no velocities relative to each other

  • every second they would get 70.4 kilometers farther away.

  • A megaparsec is 3.3 million light years though so it's a very tiny inflation.

  • Over smaller distances other forces like gravity or the strong nuclear force

  • means the expansion of space doesn't affect atoms or solid objects.

  • Dark energy could become more dense, though,

  • and given long enough the stars, planets, even atoms, could be ripped apart.

  • This is called "The Big Rip."

  • As you can tell, dark matter is the linchpin of these two theories and there's still more possibilities.

  • One of them, cosmic uncertainty, essentially throws its hands in the air and says we don't know what will happen until we understand dark energy.

  • So, clearly, figuring out this stuff will tell us a lot about our future.

  • Well maybe not our future. You and I will be long gone by the time any of these

  • scenarios would play out and the human race itself may have vanished or evolved into something unrecognizable.

  • Sadly, nobody lives to see the future but it's going to be a really interesting place.

  • So, that covers many of the prevailing ideas on how the universe will end but what happens when YOU end?

  • Trace talks about that here:

  • Firstly, at death all your muscles relax.

  • It takes burning oxygen for energy to keep you tense: no O2, no tension.

  • This includes the body's sphincters which is why death often causes defecation and incontinence.

  • Where do you think the universe is going? Let us know in the comments or Facebook or Twitter @dnews.

  • Subscribe for more answers to life's questions big and small and we'll see you next time on DNews.

We have a pretty good idea of how and when the universe began


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B2 中上級

宇宙はいつ終わるのか? (When Will The Universe End?)

  • 90 7
    Jerry Liu に公開 2021 年 01 月 14 日