You know all this is going to end, right?
Like, you and your guinea pig and the bacteria
living in your bathtub and the Real Housewives franchise?
All those things are going to end.
And of course you know that.
But also big, permanent-seeming things are going to end:
like the earth, the Sun, this galaxy,
that galaxy over there, and the universe!
The end's not going to happen soon, but give it some time,
and even the universe will change into something different
something we wouldn't even recognize.
And then POOF, gone.
How exactly that's going to happen is, of course,
up for some serious debate, because what we don't know
about the universe could fill...like, a universe.
But astrophysicists, cosmologists, and particle physicists
are pretty smart people, and they think about this all the time.
So, at this point, what do they think is going to happen to Earth,
the Solar System and the Universe in the far distant future?
It's good stuff to know, you know.
Just in case you happen to run out of other stuff to worry about.
[INTRO]
The Universe is about 13.7 billion years old,
give or take about 130 million years,
but it hasn't always been the way it is now.
It's believed that it was born with the Big Bang
as an unfathomably hot, dense point called a singularity.
The Big Bang didn't occur as an explosion like you would think,
even though it's called the Big Bang.
And the universe didn't expand into space,
because space didn't exist before the Universe was formed.
Instead, think of the Big Bang as the simultaneous appearance
of space everywhere in the universe.
You know, if you can picture that.
I, for one, cannot.
But the people who study this stuff say that the universe
hasn't expanded from any one spot since the Big Bang,
but that space itself has been stretching,
and carrying matter with it.
So, the Universe started at a single, hot, dense point
smaller than an electron or something, and at the ripe old age
of a hundredth of a billionth of a
trillionth of a trillionth of a second,
this point began to expand faster than the speed of light
in a process called inflation.
It's thought that in the same instant,
the universe doubled in size at least 90 times,
growing from the size of a subatomic particle
to the size of a golf ball, TA-DA!
Whole universe!
From there, it continued to grow a little more slowly,
and as it expanded, it cooled, and matter began to form.
For instance, just one second after the Big Bang,
the fundamental building blocks of matter, called quarks,
start to assemble into subatomic particles, like protons and neutrons.
And for the next 380,000 years or so, as the universe
continued to cool and become less dense, these particles began
to structure themselves in a way that we would recognize.
They started colliding to form atoms: protons and neutrons inside
a nucleus, tied up together with a tidy little orbit of electrons
Here, some of the first, lightest elements like helium,
lithium and of course, hydrogen began to appear.
At this point, the Universe transformed from a dense fog
of particles into something transparent,
but it also went completely black, since no stars had yet formed.
So, the period between 380,000 years to about 400 million years
after the Big Bang is what we call the cosmic dark ages,
since there weren't any big objects emitting visible light yet.
But for the next half-billion years after that, clumps of gas
began to collapse enough to form the first stars and galaxies.
The expansion of the universe gradually slowed
as gravity tried to pull matter back in on itself.
But then about 3.5 billion years after the Big Bang,
something weird started to happen:
A force stronger than gravity began to overpower this pull
and accelerate the expansion of the Universe.
This force, called dark energy, is a leading candidate
for the title of least understood thing in physics
all we really know is that it's a repulsive force
that causes the universe to expand at an ever increasing rate.
So, at this point, you probably get why the fate of Universe
is so tough to predict.
Our information is profoundly incomplete.
We keep finding out about stuff like dark energy,
and we're like, "Oh...okay.
That's gonna take a minute to process."
Anyway, a little south of 9 billion years after the Big Bang,
our solar system was born,
and then our little adorable planet showed up.
And here we are, but what's going to happen to us?
Because everything ends.
I mean the second law of thermodynamics tells us
that as time passes, entropy, that is, disorder in general
increases on all levels: stars, including our sun,
exhaust their supplies of fuel,
planets come untethered from their stars, and galaxies break apart.
We're not 100% sure about anything regarding the true nature
of the Universe, so the end could happen in a different way
in fact a lot of really smart people think it will happen differently.
But one thing pretty much everybody agrees on:
There's almost certainly going to be an end.
But here on Earth, we've got some things besides cold,
black nothing to worry about.
Even if the End of Everything does happen,
you won't be around for it neither will I, and neither will our
great-great-great-great grandkids.
They'll be past caring one way or another.
Because on Earth things are always changing:
It's what makes life possible, but it can also be
kind of un-conducive to immortality, if you know what I mean.
In the next 100,000 years, Niagara Falls will erode away
into Lake Erie, the moon will slow down the rotation
of the Earth enough that we'll have to add a "leap second"
to our clocks every day, and if global warming doesn't
tamper with it, we're due for another ice age.
Oh, and the movement of the stars will render
most of the constellations we see from Earth unrecognizable,
which will make astrologers, presumably, really confused.
In the next 1 million years, our planet is due for a good,
old-fashioned catastrophic extinction event.
These have happened periodically over the past
4 billion years of Earth's history.
It could be the eruption of a super-volcano,
which have been frequent enough to change the game
in terms of the history of life on Earth:
Think of an explosion so major that sulfuric acid
mixed with volcanic ash blocks the sun all over the world
for like 10 years and sends the planet into a volcanic winter.
It's happened before, lots of times.
We've even survived one before, although barely.
Some scientists think that the eruption of the Toba super-volcano
in Indonesia 70,000 years ago left only about 1,000 breeding pairs
of Homo sapiens to repopulate the Earth.
And did they ever!
Now, sometime in the next 100 million years,
we're likely to be hit by a meteorite similar to the one
that possibly killed off the dinosaurs,
because things in space are not so far apart
that they don't run into each other occasionally.
And big space rocks have collided with the earth
for as long as there has been an Earth.
In fact, that's probably what's caused
most of the major extinction events on earth so far.
Of course, some people think we could destroy one of these
space rocks before it punches us in the face, but who knows
where humans will be, if anywhere, 100 million years from now.
250 million years from when you watch this,
we will make a full circuit around the Milky Way,
in which time all the continents on Earth
may have fused into a single supercontinent.
And now we have to start thinking about the sun getting bigger,
because that's what's going to happen next.
In 600 million years, the sun will begin to enter
the red giant phase, basically a star's midlife crisis.
A red giant has fused all its hydrogen into helium, causing it
to heat up and expand to more than 100 times its original size.
It'll take a few billion years for the sun to actually swallow
the Earth, but its growing luminosity will probably cause
enough climatic changes on earth
like all the oceans evaporating, for instance
that in 1.3 billion years, all plants and animals
will have gone extinct, and the only living things
will be bacteria and archaea, hanging out in
little pockets of liquid water at the earth's poles.
In 1.6 billion years, even those extremophiles
will be having a tough time of it.
In about 3.5 billion years,
the surface of earth will resemble that of Venus,
and earth's orbit will widen with the growing,
yet less massive, sun, until about 7.9 billion years from now,
when the sun will swallow up Mercury, Venus and Earth.
Some researchers have suggested that if humankind has figured out
how to survive that long, maybe we could lasso a passing asteroid
and get a tow into wider orbit.
OR!
OR we could move onto one of Saturn's moons, like Titan,
because at that point it might be a perfect place for us.
7.9 billion years though, we are so not gonna be around...
but I love the optimism.
Anyway, 8 billion years from now, the sun will become a white dwarf,
which, by that point will be about half its present mass,
and by 14.4 billion years from now, it will be cool enough
to be invisible to human eyes.
It's been a good sun though,
you better appreciate while it's still keeping you warm.
After that, our solar system is pretty much dead.
Now, it's kind of hard to say what will happen to the Universe.
Every astrophysicist's got ideas, of course,
and each idea has a kind of painful nickname:
The Big Rip, The Big Crunch, The Big Freeze.
Which scenario will win out mostly depends on dark energy,
which we don't know diddly about, if you remember.
Let's start with the Big Rip.
Here, the rate of expansion driven by dark energy
keeps growing and growing without limit, becoming so extreme
that it actually overwhelms all of the fundamental forces of physics
from the gravitation between objects to the strong and weak forces
that hold subatomic particles together.
In which case, not only will galaxy clusters break apart
and star systems dissipate, but every form of matter,
right down to molecules and atoms, will be shredded into oblivion.
Some physicists say that this could
happen as soon as 17 billion years from now.
Or, another possibility is that
oh, like 100 billion years from now, the strength of dark energy
will diminish as time goes on
and the expansion of the universe will stop accelerating.
In this case, if dark energy weakens, gravity might ultimately
win the tug of war and pull all the matter
in the universe back on itself.
That result is referred to as The Big Crunch.
But these days, a lot of bets are being placed on The Big Freeze.
In this scenario, dark energy keeps the universe flying apart
until everything gets so far flung that
there's simply no thermodynamic energy left.
There'll be no motion, no heat, no life.
Stars will burn out, new stars will stop forming,
and the cosmos will dissipate into cold, dark nothingness.
This party isn't expected to start for about
100 trillion years though, so that's good news.
But these aren't the only ideas, they're just the most popular ones.
Some cosmologists think that as entropy in the Universe increases,
it will configure itself into something so complicated,
it will become a self-aware entity.
Sooooooo, yeah.
I'm with the guy who thinks
the universe could become a giant brain.
That sounds cool.
But that's what's great about this stuff:
cosmologists are constantly bickering over questions like,
Is the Universe even real?
Are we real?
How many Universes are there?
Is the universe going to recur
over and over again in an endless cycle of Big Bangs?
Why can't you unscramble an egg?
Because when you're trying to figure out the Nature of the Universe
from a tiny rock in deep space, there are no stupid questions.
If you have any comments, questions or ideas
you can get in touch with us on Facebook, Twitter or of course,
down in the comments below.
And we will endeavor to be a part of this discussion,
which is bound to be a somewhat complicated one.
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