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Three Ways to Destroy the Universe

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    One day the universe will die.
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    But why? And how? And will the universe
    be dead forever?
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    And how do we know that?
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    First of all, the universe is expanding.
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    And not only that, the rate of
    its expansion is accelerating.
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    The reason: dark energy.
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    Dark energy is a strange phenomenon that
    scientists believe permeates the universe.
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    Until 1998 we thought that the universe
    must work a bit like
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    a ball that you throw into the sky.
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    The ball moves up, but at some point
    it has to come down again.
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    But the expansion of the universe
    is actually speeding up.
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    That’s like throwing a ball up
    and watching it fly away
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    faster and faster and faster.
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    Where is this acceleration coming from?
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    Well, we don’t know, but
    we call it “dark energy”.
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    Einstein thought of it first and
    then decided it was stupid.
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    Now, astrophysicists have
    decided it is plausible.
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    Trouble is, this is all very theoretical,
    and we don’t actually know
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    what the properties of dark energy are.
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    But there are various theories and they
    lead us to three scenarios
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    for the end of the universe.
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    One: the Big Rip.
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    Since its birth, the universe
    has been expanding.
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    For unknown reasons new spaces
    created everywhere equally.
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    The space between galaxies expands,
    so they move apart.
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    The space inside galaxies also expands,
    but here, gravity is strong enough
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    to keep them together.
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    In the Big Rip scenario, the expansion
    accelerates up to a point where
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    space expands so fast that gravity
    can’t compensate for this effect anymore.
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    The result is a Big Rip.
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    At first, only large structures like
    galaxies are torn apart,
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    since space between the single objects
    expands very fast.
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    Next, big bodies like black holes,
    stars, and planets die.
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    Their gravity isn’t strong enough to keep
    them together,
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    so they dissolve into their components.
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    In the end, space would expand
    faster than the speed of light.
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    Atoms would now be affected,
    and they would just disband.
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    Once space is expanding faster than light,
    no particle in the universe can interact
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    with any other particle anymore.
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    The universe would dissolve into countless
    lonely particles that won’t be able to
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    touch anything else in a strange,
    timeless universe.
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    Hmm, and you thought you felt lonely!
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    Two: Heat death or a Big Freeze.
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    In a nutshell, the difference between
    the Big Rip and heat death is that
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    in a heat death scenario matter stays
    intact and is converted
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    over an incredibly long but finite period
    of time into radiation,
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    while the universe expands forever.
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    But how does this work?
    Let’s talk about entropy.
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    Every system tends towards the
    state of highest entropy,
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    like when we have a latte macchiato.
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    Initially, it has different regions, but
    over time, they will
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    cool down and disintegrate,
    until it’s uniform.
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    And this also applies to the universe.
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    So, while the universe gets
    bigger and bigger,
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    matters slowly decays and spreads out.
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    At some point, after lots of generations
    of stars, all the gas clouds necessary
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    to form stars will be exhausted,
    so the universe will turn dark.
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    The remaining suns will die;
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    black holes will slowly degenerate
    and evaporate over trillions of years
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    due to what’s known as Hawking radiation.
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    When this process is complete, only a
    dilute gas of photons and light particles
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    remains, until even this decays.
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    All activity in the universe ceases
    at this point;
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    entropy is at its maximum and
    the universe is dead forever.
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    Unless… theoretically, it might
    be possible
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    that after an incredibly
    long amount of time,
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    there might be a spontaneous entropy
    decrease as a result of something called
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    “quantum tunneling”, leading to
    a new Big Bang.
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    Three: Big Crunch and Big Bounce.
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    This is the most uplifting scenario.
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    If there is less dark energy than we think
    or it decreases over time, gravity will be
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    the dominating force in the
    universe one day.
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    In a few trillion years, the rate of
    expansion of the universe
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    will slow down and stop.
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    After that, it reverses.
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    Galaxies will race at each other,
    merging as the universe becomes
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    smaller and smaller.
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    Since a smaller universe also means
    a hotter universe, temperatures rise
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    everywhere all at once.
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    One hundred thousand years before the Big
    Crunch, background radiation would be
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    hotter than the surfaces of the
    most stars, which means that
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    they would be cooked from the outside.
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    Minutes before the Big Crunch happens,
    atom cores are ripped apart,
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    before supermassive black holes
    devour everything.
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    Finally, all black holes would emerge into
    a supermassive mega-black hole
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    that contains the entire
    mass of the universe,
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    and in the last moment before
    the Big Crunch
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    it would devour the universe,
    including itself.
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    The Big Bounce theory states that this
    has happened a lot of times
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    and that the universe goes through
    an infinite cycle of
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    expansion and contraction.
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    Well, wouldn’t that be nice?
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    So what will actually happen to
    the universe in the end?
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    At the moment, heat death seems the most
    likely, but we at Kurzgesagt hope that
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    this “dead forever” stuff is wrong and the
    universe will start over and over again.
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    We don't know for sure either way, so
    let’s just assume
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    the most uplifting theory is true.
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    By the way, we have a Twitter account.
Title:
Three Ways to Destroy the Universe
Description:

How will the Universe die?

Everybody dies. The universe too? Well, probably. What are the current theories about the end of everything? And how creepy exactly are these theories? (Spoiler: very creepy). But there might be hope...

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Next Video: March 3rd. Topic: The Big Bang (which concludes our mini series about the universe)

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Will the Universe Die?

Three Ways to Destroy the Universe

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Video Language:
English
Duration:
06:17

English subtitles

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