Hi, I'm John Green, and this
is Crash Course Big History
in which we'll be looking at the
history of, like, everything.
I'm talking about
13.8 billion years--
from the Big Bang to now.
I mean, in this series, we are
literally going to attempt
to tell you the story of what
Douglas Adams famously called:
>> Mr. Green, Mr. Green!
That's not history,
that's science.
And science is for nerds.
Oh, me from the past, things
would be so much easier
for you if you would
just accept that you are,
in fact, a nerd and that's okay.
I mean, look at
this picture, dude.
Anyway, academics often
describe history
as, like, all the stuff
that's happened
since we started
writing things down,
but they only start there
because that's where we have
the best information.
And, yeah, I think
that the advent
of writing was a huge deal,
obviously,
but as a start date for history,
it's totally arbitrary.
It's just a line we drew
in the sand and said,
"Okay, history begins now!"
In Big History, we're going
to start history
when it really starts--
at least, we think--
at the creation of the Universe.
And we're going to end
that story where it ends.
Please let that be after I die.
Well, I guess it will definitely
be after I die,
it's just, I want it
to be a while after I die.
So we're even going to terrify
traditional historians
by using physics to make some
predictions about the future
and we're going to end many
trillions and trillions
of years from now
when the Universe itself--
spoiler alert-- dies, at least
in a manner of speaking.
Hey!
I'm not John.
If you're thinking we look a
little bit the same,
that's because we're brothers.
I'm Hank.
Anyway, if you want to learn
the 13.8-billion-year history
of the Universe in the same
amount of time
that we usually cover the 238
years of American history,
you're not going to get
the same resolution.
Of course, knowing
the names and dates
of American history
is important,
but we just can't do that
in Big History.
As you zoom out, you see a lot
more of the picture.
The details get a little fuzzy,
but we quickly realize
that history is everything--
cosmology, geology,
biology, social sciences,
literature, physics.
Everything.
You might think that such
a scale would be filled
with way too much detail,
but the amount of detail
an answer requires depends
on the nature of the question.
Some questions can only be
explored by zooming out.
That is what Big History does.
Speaking of zoomed out,
this is"Earthrise,"
one of the most famous
photographs of all time.
William Anders,
an Apollo astronaut,
took it in 1968.
From the surface
of another world,
we see our planet
as a little ball in space.
No borders, no people,
no buildings,
just oceans and clouds
and continents
being shined upon by the sun.
That sheer expansion of scale
gives me perspective.
It lets me imagine all the
complexity of life on Earth,
from the gasoline engine
that powered my trip
to the studio,
to political instability
in Nepal as part of a thriving,
living, teeming mass of life
loading in the emptiness
of space.
So what that photograph
does for physical space,
Big History aims
to do for everything.
I mean, we want to contextualize
all of existence.
We want to outline
the most powerful
and important breakthroughs, the
tremendous scale of existence,
and how we know what we know,
and why we're sure we know it.
All right, let's go
to the Thought Bubble.
So, the Universe is big--
like, really big--
and it's also old--
like, 13.8 billion years old.
Which is enough years
that there is no way
to actually comprehend it,
so let's just compress
that age to 13 years--
small enough that our puny
brains can handle it.
On that time scale, the Universe
would have begun 13 years ago,
in 2001.
George W. Bush had just been
sworn in as president.
Most Americans on the Internet
were connecting
to it with dial-up modems.
Right, so the first stars
and galaxies
would have formed 12 years ago,
but seven and a half more years
would pass until the earth
formed, about 4.5 years ago.
Move a little bit up
to four years ago--
that's when the first
single-celled life formed
on Earth.
Then leap forward nearly three
and a half more years
before the first
multicellular organisms
and the Cambrian explosion...
What I'm trying to explain is
that all complex life
on Earth is a fairly
recent development.
Like, on this scale,
the dinosaurs went extinct
about three weeks ago--
roughly the last time
I changed my Facebook status.
Humans and chimpanzees split
from their last shared ancestor
about three days ago.
The first homo sapiens
emerged 50 minutes ago,
roughly the last time
I checked my email.
We left Africa 26 minutes ago.
The American Indians reached the
Americas six minutes ago--
roughly the last time
I check my Twitter.
We invented agriculture
five minutes ago,
Ancient Egypt three minutes ago,
the Black Death 24 seconds ago,
The Industrial Revolution,
six seconds,
World War I, two seconds.
The Cold War, the first man
on the moon, your birth,
the internet, the Big Mac,
all within the last second.
But in many other ways,
complex life
and humanityareexceptional.
>> Thanks, Thought Bubble.
Also exceptional, by the way,
the Mongols.
Okay, let's begin at the
beginning-- the Big Bang.
Hank, wait a second...
whoa, whoa, whoa.
I don't understand how
we know that the Big Bang
is really the beginning.
Like, what happened
before the Big Bang?
Well, okay, theoretical
physicists say
that space and time are not
two different things.
They are two expressions
of one thing: spacetime.
And spacetime was created
by the Big Bang,
thus, time didn't exist
before the Big Bang,
so it doesn't make much sense
to ask what happened before it.
There was no "then" then.
Of course, this, like many
ideas in cosmology,
doesn't really make any sense
to our puny human brains.
It's largely beyond our
comprehension
rather like explaining color
to a blind person.
We know that it's true
because the math works
and it explains our
observations so elegantly,
but it's so far outside of how
we directly perceive the world
that I don't think
it's something
even the most genius physicists
are able to imagine.
But, yeah, if you're going
to do a chronological study
of the Universe,
the creation of time
is probably a pretty good place
to start the story.
So the Big Bang wasn't
something that happened
inside the Universe, nor did it
expand into some kind of void.
It was literally the moment
when both time
and space were created.
The thing that was banging
was the Universe itself.
It was expanding from an
unimaginably tiny point
to an unimaginably large
Universe unimaginably quickly.
"Unimaginable" is basically
the subtitle to the story
of the Big Bang, but then again,
it's also kind of the subtitle
to everything else
in Big History.
I mean, I can only
do this occasionally,
but sometimes you look
outside and you're like,
"Oh, my goodness, this is nuts!
How did we get trees?"
Needless to say, we will be
talking about that.
Anyway, the Universe
is a hard worker
and it got most of the
heavy lifting done
in those first few seconds.
For comparison, it takes me
about 20 minutes
after I wake up for me
to even get myself
into a standing position.
But the Universe is
somewhat more efficient.
In the barest fraction
of the first second,
the Universe inflated
from something many, many, many
times smaller than an atom
to about the size
of a grapefruit.
Like, think of it this way.
In much less than
a blink of an eye,
if it had originally been
the size of a tennis ball,
it would have inflated to over
90 billion light-years across.
This inflation theory
has been well backed up
by mathematics
for a long time now,
but it has recently received
some staggering new support
from the BICEP Project
of the South Pole
which sadly has nothing
to do with my guns.
Ten seconds after the Big Bang,
the Universe had expanded enough
that the normal rules
of the Universe
with atomic forces and gravity
and electromagnetism
that we know and love today
were already in charge.
All of the antimatter created
in the Big Bang had combined
with matter and
annihilated itself leaving
behind only one-billionth of the
matter created in the Big Bang.
And that billionth is
everything.
And I mean everything--
every grain of sand,
every blueberry
you will ever eat,
every star that
you will ever see.
Everything.
We're already tried to
understand how big a billion is,
but just pause
to think about that.
Everything--everything--
is one-billionth of the matter
created in the Big Bang.
(imitates explosion)
The First Law of Thermodynamics
is that
matter and energy cannot be
created or destroyed.
Everything we have now,
we had then.
The matter that makes up your
body right now has been around
since those moments
13.8 billion years ago.
It's simply changed form.
After just three minutes,
the Universe was cool enough
that the nuclei of atoms
started forming--
just hydrogen and helium back
then, the two simplest elements.
Keep those two in mind, however,
because it turns out
if you take a bunch of hydrogen
and you wait, like,
several billion years, you might
just grow yourself some humans.
Let's remember, at this time,
the Universe was still
very, very hot.
I don't want to use the world
"unimaginable" too often.
But it was unimaginably hot.
The Universe remained, like,
an uber hot sea dominated
by radiation, but then
luckily it simmered down
to a balmy 5,000
degrees Fahrenheit
about 380,000 years
after the Big Bang,
allowing matter
and radiation to separate.
And remember:
I mean, you are a somewhat
firm bag of energy.
In my case, I'm not that firm.
So anyway, at 5,000
degrees Fahrenheit,
radiation was finally able
to move freely
through the Universe,
and we see that radiation today
as the end of the dark ages
that followed the Big Bang
and the beginning of a brilliant
flash that we call:
Which is a great
name for a band.
Physicists call it "The
fingerprint of the Universe"
and it's one of the most
important pieces
of historical evidence
we have for the Big Bang
because CBR is everywhere.
Tune your radio to a frequency
that doesn't have a station,
a portion of the static
you hear is actually
that cosmic background radiation
being picked up by your radio.
So you can literally hear the
Universe in its infancy.
Sometimes it can be tricky
to know what's true,
especially when we're
talking about stuff
that happened so far
in the distant past.
That is why we created science:
So just using your limited human
senses, you might come
to the same conclusion
as 19th century scientists--
that the Universe is static,
eternal, and infinite.
Then, using our minds,
if the Universe is infinite--
it contains infinite stars
and it has always existed--
then the night sky and the
daytime sky for that matter
would literally be
filled with stars,
so much that day and night
would be indistinguishable.
This is clearly not the case,
so something must be amiss.
The Universe must either
be not static,
not infinite, or not eternal.
So which is it?
You know how when an ambulance
drives towards you,
the sound waves are compressed
and the siren sounds
higher pitched,
and as it speeds away the waves
are stretched out
and the pitch is lower?
It's the Doppler effect.
Well, here's another
name you've heard:
Edwin Hubble.
He realized that light
does the same thing.
Galaxies in stars moving away
from us have their lights
stretch out,
making it more red,
and stars moving toward us
have their light compressed,
making it more blue.
Combined with the work
of Henrietta Leavitt,
which allowed us to accurately
estimate how far away stars are,
Hubble was able to
determine that stars
on the whole are flying
away from each other.
He discovered that the
most remote objects
in the sky were all red-shifted
and were actually
other galaxies beyond the
Milky Way moving away from us.
From here,
he built upon the work
of Belgian Catholic priest
Georges Lemaitre
who hypothesized
that the Universe began
at a single point.
Big Bang cosmologists
wanted proof, though.
They knew that the amount
of radiation released
by the Big Bang would be massive
and they wanted to see it.
It wasn't until the 1960s that
it was found-- accidentally--
by two guys working
on an antenna
at Bell Laboratories
in New Jersey.
They were trying to eliminate
all the background noise
from an extremely
sensitive radio antenna,
but they found this faint hum
coming from every direction.
They tried everything
they could to get rid of it,
including murdering the pigeons
that kept pooping
on the antenna.
Kind of sad, but those pigeons,
they gave their lives
for one of the most profound
discoveries in modern science.
A conversation with a local
radio astronomer led them
to show their findings
to an astronomer
at Princeton who
confirmed the existence
of what had been predicted
for years.
The final piece of that Big Bang
puzzle is that we can see it.
Light has a speed.
When we look at the sun,
we're seeing the light
that left it eight minutes ago.
But if we look at something
that's 13.8 billion
light-years away,
we're seeing the stuff that
happened 13.8 billion years ago.
That radiation
has been traveling
since the very beginning
of the Universe.
Not only can we
tell very clearly
that there was just nothing
there before that,
we can now study that radiation
to learn the sequence
of events of the Big Bang.
We can also see that the
chemical composition
of the early Universe is
what we'd expect to see.
A lot of hydrogen,
a lot of helium,
and a tiny pinch of lithium.
The rest of the period
table had to wait
for the fiery furnaces in the
bellies of stars to be created.
But more on that next episode.
As far as we've come
in the past century
in crafting a history
of the Universe,
there are still many things
cosmologists
have yet to discover.
For instance,
the Universe behaves
as if there's a bunch
of matter in it
that we can't see or detect.
Galaxies' gravitation is
affected by this matter,
but it's otherwise
completely invisible to us.
Physicists call
it "dark matter"
but we have no idea what it is.
But as in any historical
endeavor,
new discoveries will alter
the story in future years,
so expect the Big Histories
of ten or 20 years from now
to look very different
from today's.
But this isn't discouraging
because, like,
knowing everything
would be boring.
There's a lot left to discover
and at the current pace
of scientific inquiry, many
of those amazing discoveries
will await us in our lifetime--
or at least in your lifetime.
- Whether it be World War II
or the life of Abe Lincoln,
all histories ultimately start
with the Big Bang.
Yeah, it would be silly to start
your typical World War II
textbook with the Big Bang,
but it would be about 100
trillion trillion times
more ridiculous to say
the Big Bang,
the mother of all historical
events, was not history.
And that's why
Big History reaches
into the lives of every person
on this tiny speck of dust
we call home regardless of
nation, class, or creed,
and forms our common story.
See you next time.
