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(gentle chiming music)

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- [Narrator] A lot has
changed in the last 50 years,

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especially in our
understanding of the cosmos.

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- The last 50 years, I think,

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have been the most
exciting ever.

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Our entire understanding
of the universe

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just turned upside down.

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- [Narrator] Welcome
to the dark universe,

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where powerful, yet invisible
dark matter holds cosmic sway,

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shaping even the very
galaxy we call home.

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- Dark matter is four times
or five times more abundant

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than the stuff we can see.

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It is fundamentally disturbing.

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(dramatic music)

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- [Narrator] But
we're on the hunt.

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- We're entering
discovery territory.

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- [Narrator] And the
darkness doesn't end there.

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A ghostly form of dark energy
dominates the universe,

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driving its expansion, maybe
even choosing its fate.

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- I don't think we
possibly could have grasped

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just how profound it was.

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- This is a huge discovery.

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- [Narrator] It
remains a total enigma.

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- We have absolutely no
idea what dark energy is.

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- [Narrator] The more we've
learned about our universe,

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the stranger it becomes.

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- This is something that
can't just be wished away.

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- That's where to look
for the next breakthrough.

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- It's potentially
Nobel Prize winning.

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- [Narrator] "Decoding the
Universe," right now on NOVA.

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(dramatic music)

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(dramatic music continues)

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♪ ♪

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NARRATOR:
September 5, 1977.

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ARCHIVAL:
Three, two, one...

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...and we have lift-off!

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NARRATOR:
A Titan-Centaur rocket

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carrying the space probe,
Voyager 1,

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launches from Cape Canaveral.

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REPORTER:
The Voyager spacecraft
to extend man's senses

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farther into the
solar system than ever before.

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NARRATOR:
The Voyager program would become

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NASA's longest mission to date.

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KAISER:
I absolutely remember
the coverage.

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I remember watching the launch--
it was really exciting.

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I had no sense of the scale of

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where that thing was headed,

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to where no human-built things
had ever gone before.

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NARRATOR:
In 1979,
Voyager 1 flies past Jupiter.

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(applause)

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♪ ♪

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About a year-and-a-half later,
Saturn.

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♪ ♪

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Though it will
continue on its journey,

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in 1990,
it sends its last images.

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Looking back
at the solar system...

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...Earth is just a tiny speck.

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In Carl Sagan's words,
"a pale, blue dot."

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KÖNIG:
The Pale Blue dot--
it's telling us,

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we're incredibly small.

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At the same time,
it also tells us

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that we've gone incredibly far.

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I mean in cosmology,
we're looking,

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we're looking at supernovae.

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We're looking at other galaxies.

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We're looking at
the beginning of the universe.

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But there's so much more
that needs to be done.

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NARRATOR:
During Voyager 1's
nearly 50-year-long mission,

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our scientific understanding
of the universe

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has grown immensely...

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...and even radically changed.

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The last 50 years, I think,

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have been
the most exciting ever.

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Our entire understanding
of the universe

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has changed,
it's just turned upside down.

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Over the past 50 years,

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there's really been

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several revolutions

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in our understanding of
the universe.

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We can both be proud
of how far we've come,

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but also be excited
about how much we don't know.

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♪ ♪

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NARRATOR:
Looking back,

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the discoveries of the last
50 years are remarkable.

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In the 1970s,
Luke Skywalker's home, Tatooine,

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was as close as we got
to seeing an alien planet.

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In the 1970s,
we knew of precisely

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zero planets outside of

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our solar system.

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And in the decades since then,

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we've moved that
number up into the thousands.

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SUSAN MULLALLY:
We've discovered planets are
incredibly common

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in our galaxy.

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There are more planets out there

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than there are stars.

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So go out
and look at the night sky.

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For every one of those stars,

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there are probably several
planets.

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NARRATOR:
And in recent decades,
we've also learned...

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...our Milky Way galaxy
isn't even one in a million.

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A fact made evident by this
astonishing series of images

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taken by the Hubble Space
telescope in 1995.

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Just about every single
bright point is a galaxy.

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Scientists now think
galaxies in the universe

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may number in the trillions.

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KÖNIG:
The Hubble pictures tell us

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that the universe
is the same everywhere.

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It's also a reminder
that we are definitely not

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the center of the universe.

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NARRATOR:
One of the most shocking
discoveries

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of the last 50 years, was made
in our own cosmic backyard.

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In 1998, astrophysicist
Andrea Ghez

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and her team
surprised the world

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when they revealed evidence
of a super massive black hole

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at the center of our own
Milky Way.

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GHEZ:
From watching stars orbit
the center of the galaxy,

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the mass that we infer is

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four million times
the mass of the sun.

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That is the proof
of a black hole.

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NARRATOR:
Astronomers now believe

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that just about every galaxy
has one.

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CLIFFORD JOHNSON:
Black holes are crucial to how
we understand galaxies.

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That is a huge
new role for black holes

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and our understanding of them.

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NARRATOR:
But perhaps the biggest
discovery of the last 50 years

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is just how much we don't know.

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Somehow we've missed much,
much more than we've discovered.

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There is some new form
of matter out in the universe,

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and it is four times

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or five times more abundant

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than the stuff we can see.

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And so that is the
shocking truth of dark matter.

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NARRATOR:
Dark matter--

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only accepted as "real" during
the last 50 years,

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and now,
one of the biggest mysteries

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in the history of science.

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So far, its effects
have only been detected

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on the cosmic stage.

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But understanding it,

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may hold the key to the
very structure of the universe.

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My mum is always like, you know,

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"Why do we have
to care about dark matter?"

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And, and the truth is

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that without dark matter,
we simply wouldn't exist.

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KAISER:
Dark matter is, in part,
the story

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of why and how we're here.

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NARRATOR:
And yet, in recent decades,
scientists have uncovered

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evidence of something that,
today,

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is even more
powerful than dark matter.

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I just, I don't think
we possibly could have grasped

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just how profound

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and how much it would change

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our view of the universe.

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It would be like as though

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you had only ever experienced
land,

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and then one day,
you discover the oceans.

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NARRATOR:
It's called "dark energy."

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Scientists now believe

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it's the most powerful force
in the universe,

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expanding its very fabric,

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pushing galaxies apart,

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and it may even be driving
the universe's ultimate fate.

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But it remains an enigma.

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We have absolutely no idea
what dark energy is to this day.

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NARRATOR:
How did our vision of
the universe

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get completely overturned
in just a few decades?

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And what new surprises

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might lie just over the horizon?

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JOHN JOHNSON:
The past 50 years
of astrophysics has shown

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that the universe is
extraordinarily creative

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in what is out there.

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And it's very
determined to consistently

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subvert our expectations.

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BAHCALL:
We are so struggling
to figure out

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the nature of our cosmos.

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And that's very humbling,
very humbling,

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yet very empowering.

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It's a,
it's a strange combination

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of the two things together.

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♪ ♪

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NARRATOR:
Since Voyager 1 left Earth,

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astrophysicists and astronomers

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have overtaken
the intrepid probe...

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...reaching farther
and farther out into space

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to gather data written
across vast expanses of time,

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and on colossal scales.

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In stars,

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nebulas,

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supernovas,

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distant galaxies

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and galaxy clusters.

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VERA RUBIN:
There's the galaxy.
We're at the object.

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NARRATOR:
And in the 1970s,
it was just such data,

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meticulous observations gathered
by an astronomer,

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that forced scientists

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to confront the idea
of dark matter.

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The astronomer's
name was Vera Rubin.

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You'll get a guide star,

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I'll set up for the observation.

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♪ ♪

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NARRATOR:
Rubin was born
in 1928 in Philadelphia.

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From a young age,
she was hooked on the stars.

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RUBIN:
By about age 12,
I would prefer to stay up

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and watch the stars
than going to sleep.

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There was just nothing
as interesting in my life

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as watching stars every night.

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I knew I wanted to be
an astronomer.

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NARRATOR:
In 1963,

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Vera Rubin traveled here,

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to the Kitt Peak National
Observatory

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in the Schuk Toak District
on the Tohono O'odham Nation,

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56 miles southwest
of Tucson, Arizona.

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00:11:12,366 --> 00:11:15,266
Despite having advanced
degrees for over a decade,

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Rubin had never been
able to collect her own data.

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Astronomy had few women,

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and many observatories
weren't welcoming.

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Some officially
did not allow women.

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But the National Observatory
at Kitt Peak

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had just recently opened

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and accepted her application.

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She would return
to Kitt Peak several times

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over her career as she began
to focus more on galaxies.

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So Vera Rubin really was what

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I would call a true
observational astronomer.

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She loved
to go to the telescope,

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do the observation,

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take it to her office
and analyze them,

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and try to see what it told her
about the galaxies.

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NARRATOR:
Today, in more ways than one,

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Stanford Cosmologist
Risa Wechsler

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follows in Rubin's footsteps.

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So this instrument behind me

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is the 84-inch
telescope at Kitt Peak.

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Vera Rubin started using
it in 1968

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when she started making
measurements

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00:12:26,333 --> 00:12:28,066
of the Andromeda Galaxy,

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and looking at how different
regions

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in Andromeda were moving.

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NARRATOR:
Rubin wanted to check
a common assumption

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among astronomers about
galaxies.

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The presumption was that stars

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near the center of a galaxy
would be orbiting very rapidly,

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and stars at the outside
would be going very slowly.

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NARRATOR:
That idea came from the way

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the planets in our solar
system orbit our massive sun.

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Because the attractive
force of the sun's gravity

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falls off with distance,

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00:13:01,133 --> 00:13:03,633
the farther away from the sun
a planet orbits,

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the slower its orbital speed.

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Astronomers assumed
the stars in a galaxy

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would behave the same way.

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Like the sun in our
solar system,

253
00:13:15,333 --> 00:13:18,200
the bright, star-packed center
of a galaxy

254
00:13:18,200 --> 00:13:20,200
appeared to hold most
of the galaxy's mass.

255
00:13:20,200 --> 00:13:24,833
So a galaxy's orbiting stars
should act like the planets,

256
00:13:24,833 --> 00:13:28,666
with orbits slowing
toward the galaxy's outer edges.

257
00:13:28,666 --> 00:13:32,266
But no one had done
the work to know for sure.

258
00:13:32,266 --> 00:13:36,700
Partly, it was a technical
issue, which Rubin solved

259
00:13:36,700 --> 00:13:39,366
by teaming up with
instrument maker Kent Ford.

260
00:13:39,366 --> 00:13:41,500
He had developed a device

261
00:13:41,500 --> 00:13:44,166
that enhanced a telescope's
light sensitivity,

262
00:13:44,166 --> 00:13:46,833
making it possible
to finally see

263
00:13:46,833 --> 00:13:51,200
the faint stars on
the far edges of galaxies.

264
00:13:51,200 --> 00:13:54,566
And what they saw was
surprising.

265
00:13:54,566 --> 00:13:56,500
WECHSLER:
They found that

266
00:13:56,500 --> 00:13:59,633
the regions of Andromeda that
were quite far out

267
00:13:59,633 --> 00:14:01,300
were still rotating quite fast,

268
00:14:01,300 --> 00:14:03,133
faster than you would have
expected

269
00:14:03,133 --> 00:14:04,766
by the amount
of light that was there.

270
00:14:05,600 --> 00:14:08,700
NARRATOR:
It was a strange observation.

271
00:14:08,700 --> 00:14:11,566
What was keeping
those fast-moving

272
00:14:11,566 --> 00:14:14,166
outer stars from flying off?

273
00:14:15,200 --> 00:14:17,133
During the 1970s,

274
00:14:17,133 --> 00:14:19,733
Rubin and Ford,
along with other astronomers,

275
00:14:19,733 --> 00:14:24,166
gathered more and more data
from more and more galaxies.

276
00:14:24,166 --> 00:14:27,633
Almost none showed
the speed of orbiting stars

277
00:14:27,633 --> 00:14:30,100
dropping as had been expected.

278
00:14:30,100 --> 00:14:34,666
Still, it would take years
for the astronomy community

279
00:14:34,666 --> 00:14:37,200
to accept the astonishing
explanation

280
00:14:37,200 --> 00:14:40,200
that Rubin and others proposed;

281
00:14:40,200 --> 00:14:44,166
that there was a vast amount
of hidden matter

282
00:14:44,166 --> 00:14:46,700
surrounding each galaxy,

283
00:14:46,700 --> 00:14:50,300
gravitationally
holding it together.

284
00:14:50,300 --> 00:14:53,833
Aside from that effect,
it was undetectable.

285
00:14:53,833 --> 00:14:56,066
AMON:
If you didn't have some

286
00:14:56,066 --> 00:14:57,833
invisible mass in the galaxy,

287
00:14:57,833 --> 00:15:00,133
the stars would not be bound
in this, in this orbit.

288
00:15:00,133 --> 00:15:01,633
They would fly out.

289
00:15:01,633 --> 00:15:05,700
RUBIN:
We now know that
in every galaxy we study,

290
00:15:05,700 --> 00:15:08,400
the stars at
very large distances

291
00:15:08,400 --> 00:15:11,566
are orbiting with
very high velocities.

292
00:15:11,566 --> 00:15:15,100
And that tells us that
there is a lot of matter

293
00:15:15,100 --> 00:15:17,666
at very large
distances from the center.

294
00:15:17,666 --> 00:15:21,233
So we see a lot of matter where
we don't see very much light.

295
00:15:21,233 --> 00:15:24,533
And that has led
to the concept of dark matter.

296
00:15:27,833 --> 00:15:30,066
NARRATOR:
Dark matter.

297
00:15:30,833 --> 00:15:34,400
Astronomer Fritz Zwicky
had proposed the name

298
00:15:34,400 --> 00:15:36,166
in the 1930s

299
00:15:36,166 --> 00:15:39,233
to describe an "unseen mass"

300
00:15:39,233 --> 00:15:41,600
to explain some puzzling
observations

301
00:15:41,600 --> 00:15:43,400
of a nearby galaxy cluster.

302
00:15:43,400 --> 00:15:47,133
But the idea had been
largely ignored

303
00:15:47,133 --> 00:15:50,066
until Rubin and Ford came along.

304
00:15:51,066 --> 00:15:53,200
Today, scientists estimate

305
00:15:53,200 --> 00:15:56,100
there is five times more
dark matter

306
00:15:56,100 --> 00:15:58,333
than ordinary matter
in the universe.

307
00:16:00,666 --> 00:16:03,833
It's arranged in
a vast web-like structure

308
00:16:03,833 --> 00:16:07,100
of filaments and nodes.

309
00:16:07,100 --> 00:16:11,400
In the early universe,
those nodes, through gravity,

310
00:16:11,400 --> 00:16:13,833
attracted regular matter

311
00:16:13,833 --> 00:16:17,833
which eventually
evolved into galaxies.

312
00:16:17,833 --> 00:16:21,133
But what is dark matter?

313
00:16:21,133 --> 00:16:24,500
PEREZ:
Over the last 50 years,

314
00:16:24,500 --> 00:16:27,166
this question has become
a guiding question

315
00:16:27,166 --> 00:16:30,100
for huge swaths
of the physics community.

316
00:16:30,100 --> 00:16:33,700
We've had some of
the smartest people in the world

317
00:16:33,700 --> 00:16:37,133
banging heads
against the wall for decades.

318
00:16:37,133 --> 00:16:39,600
This is a really hard problem.

319
00:16:41,166 --> 00:16:43,166
NARRATOR:
There aren't many clues.

320
00:16:44,700 --> 00:16:47,266
Aside from
its gravitational effect,

321
00:16:47,266 --> 00:16:51,800
dark matter appears to interact
very little with normal matter,

322
00:16:51,800 --> 00:16:54,600
and can pass right through it.

323
00:16:54,600 --> 00:17:01,166
It also emits no electromagnetic
radiation, no light.

324
00:17:01,166 --> 00:17:05,533
There are forms of matter that
simply don't glow like stars do,

325
00:17:05,533 --> 00:17:09,200
but actually they're also not
responding to light.

326
00:17:09,200 --> 00:17:11,633
So they are invisible,

327
00:17:11,633 --> 00:17:14,166
except through
their gravitational force.

328
00:17:14,166 --> 00:17:17,066
It probably
is something quite exotic.

329
00:17:17,066 --> 00:17:19,166
It isn't any
of the ordinary stuff.

330
00:17:19,166 --> 00:17:23,133
NARRATOR:
So who are the suspects
for dark matter?

331
00:17:24,700 --> 00:17:29,833
There are the MACHOs; the
Massive Compact Halo Objects,

332
00:17:29,833 --> 00:17:33,333
like primordial black holes.

333
00:17:33,333 --> 00:17:35,166
CLIFFORD JOHNSON:
Black holes that go back

334
00:17:35,166 --> 00:17:37,133
to the very earliest eras
of the universe

335
00:17:37,133 --> 00:17:39,600
could be a major
component of dark matter.

336
00:17:40,600 --> 00:17:44,266
NARRATOR:
For a primordial black hole
to fit the bill as dark matter,

337
00:17:44,266 --> 00:17:47,133
it would have about
the mass of an asteroid,

338
00:17:47,133 --> 00:17:49,733
and be about the size
of an atom.

339
00:17:51,100 --> 00:17:53,266
And there are axions--

340
00:17:53,266 --> 00:17:57,266
minuscule particles
theorized by physicists.

341
00:17:57,266 --> 00:18:00,100
An axion, if it exists,

342
00:18:00,100 --> 00:18:03,100
interacts only very
infrequently with light,

343
00:18:03,100 --> 00:18:06,733
and it does have some mass,
so it could be dark matter.

344
00:18:09,133 --> 00:18:13,800
NARRATOR:
But the suspects who garnered
early fans were the WIMPs;

345
00:18:13,800 --> 00:18:17,733
Weakly Interacting
Massive Particles.

346
00:18:20,066 --> 00:18:22,600
The search for WIMPs leads here,

347
00:18:22,600 --> 00:18:25,733
to the Black Hills
of South Dakota.

348
00:18:25,733 --> 00:18:30,300
Native Americans have long
considered the area sacred,

349
00:18:30,300 --> 00:18:34,333
and the Fort Laramie Treaty
of 1868

350
00:18:34,333 --> 00:18:38,566
included the Black Hills
in the Great Sioux Reservation.

351
00:18:40,066 --> 00:18:41,700
But just a few years later,

352
00:18:41,700 --> 00:18:45,700
the discovery of gold
and an influx of miners,

353
00:18:45,700 --> 00:18:50,133
led to the Great Sioux War
of 1876.

354
00:18:51,800 --> 00:18:54,333
The U.S. government
seized the area,

355
00:18:54,333 --> 00:18:57,700
and forcibly relocated
its Sioux inhabitants.

356
00:18:58,833 --> 00:19:04,100
The dispute over the broken
treaty remains unresolved.

357
00:19:05,766 --> 00:19:08,833
♪ ♪

358
00:19:08,833 --> 00:19:11,366
Today, in the town of Lead,

359
00:19:11,366 --> 00:19:14,133
a retired gold mine houses

360
00:19:14,133 --> 00:19:18,533
the Sanford Underground
Research Facility.

361
00:19:18,533 --> 00:19:21,166
(elevator rumbling)

362
00:19:24,633 --> 00:19:28,166
(rattling)

363
00:19:28,166 --> 00:19:30,100
Chamkaur Ghag,

364
00:19:30,100 --> 00:19:32,833
a professor at University
College London,

365
00:19:32,833 --> 00:19:34,400
is a founding member

366
00:19:34,400 --> 00:19:36,633
of a team of researchers drawn
from universities

367
00:19:36,633 --> 00:19:38,133
around the world

368
00:19:38,133 --> 00:19:40,833
that's on
the hunt for dark matter,

369
00:19:40,833 --> 00:19:45,600
in the form of WIMPs.

370
00:19:45,600 --> 00:19:48,600
To get down a mile,
um, takes a bit of time.

371
00:19:49,966 --> 00:19:56,000
NARRATOR:
Why build a dark matter WIMP
detector so far underground?

372
00:19:57,433 --> 00:19:59,633
GHAG:
So a mile of rock
above us here

373
00:19:59,633 --> 00:20:01,800
in the Black Hills of
South Dakota

374
00:20:01,800 --> 00:20:03,733
that shield us from
cosmic radiation,

375
00:20:03,733 --> 00:20:06,333
that is bombarding us
all the time.

376
00:20:06,333 --> 00:20:07,833
And being underground,

377
00:20:07,833 --> 00:20:10,300
we're able to reduce that by
factors of millions.

378
00:20:10,300 --> 00:20:12,433
So this experiment
up on the on the surface just

379
00:20:12,433 --> 00:20:14,100
wouldn't be able to run at all.

380
00:20:14,100 --> 00:20:15,633
It's just far too sensitive.

381
00:20:18,533 --> 00:20:20,333
WORKER:
And then go ahead,
hop on the train.

382
00:20:20,333 --> 00:20:21,566
Ready?
Yep.

383
00:20:22,366 --> 00:20:24,433
NARRATOR:
After the ten minute ride down,

384
00:20:24,433 --> 00:20:28,366
it's on to
a battery-powered locomotive,

385
00:20:28,366 --> 00:20:30,433
followed by a brief hike

386
00:20:30,433 --> 00:20:32,733
to get to the cavern

387
00:20:32,733 --> 00:20:35,800
that holds the lab

388
00:20:35,800 --> 00:20:40,133
of the LUX-ZEPLIN
or LZ detector experiment.

389
00:20:45,466 --> 00:20:47,166
GHAG:
The core of the experiment

390
00:20:47,166 --> 00:20:49,233
is xenon, it's liquid xenon.

391
00:20:49,233 --> 00:20:50,466
It's xenon gas
that's been condensed.

392
00:20:50,466 --> 00:20:52,066
And we've got to keep
that clean,

393
00:20:52,066 --> 00:20:53,266
and we've got to keep it cold,

394
00:20:53,266 --> 00:20:55,466
and so much of what
we'll see around here

395
00:20:55,466 --> 00:20:56,533
is all for that, really.

396
00:20:58,833 --> 00:21:01,433
NARRATOR:
Here is the main experiment.

397
00:21:01,433 --> 00:21:05,166
At its center is a
container of seven metric tons

398
00:21:05,166 --> 00:21:09,433
of very pure,
cooled liquid xenon.

399
00:21:09,433 --> 00:21:11,800
The concept is straightforward;

400
00:21:11,800 --> 00:21:15,800
the cooled xenon
is extremely sensitive.

401
00:21:15,800 --> 00:21:18,700
Even just a single collision

402
00:21:18,700 --> 00:21:21,100
between one of
the theoretical WIMPs

403
00:21:21,100 --> 00:21:23,333
and the nucleus of a xenon atom

404
00:21:23,333 --> 00:21:26,400
would cause the atom
to collide with others,

405
00:21:26,400 --> 00:21:28,666
emitting a flash

406
00:21:28,666 --> 00:21:31,133
of ultraviolet light,
which would be picked up

407
00:21:31,133 --> 00:21:34,833
by the detectors at
the top and bottom of the tank.

408
00:21:34,833 --> 00:21:38,233
The interaction would also
liberate electrons.

409
00:21:38,233 --> 00:21:42,633
They'd drift up to the top,
and emit an even bigger flash.

410
00:21:45,333 --> 00:21:47,066
GHAG:
So we get two flashes
of light here,

411
00:21:47,066 --> 00:21:48,733
and based on how these two
signals look

412
00:21:48,733 --> 00:21:50,266
relative to one another,

413
00:21:50,266 --> 00:21:53,833
we can tell whether
this was background radiation,

414
00:21:53,833 --> 00:21:56,833
or if this was a dark matter
particle that came in

415
00:21:56,833 --> 00:21:58,733
and hit
the nucleus of a xenon atom.

416
00:22:00,766 --> 00:22:05,833
NARRATOR:
LZ isn't the only experiment
using cooled xenon,

417
00:22:05,833 --> 00:22:09,700
but it now leads the pack in
sensitivity.

418
00:22:09,700 --> 00:22:11,766
It's the frontrunner now.

419
00:22:11,766 --> 00:22:13,733
And so, we're
entering discovery territory.

420
00:22:13,733 --> 00:22:16,566
NARRATOR:
Direct dark matter detection
experiments

421
00:22:16,566 --> 00:22:20,100
go back to the 1980s.

422
00:22:20,100 --> 00:22:22,433
Xenon-based experiments,

423
00:22:22,433 --> 00:22:24,633
similar in design to LZ,

424
00:22:24,633 --> 00:22:26,533
to the 2000s.

425
00:22:28,466 --> 00:22:30,500
So far,
all the experiments combined

426
00:22:30,500 --> 00:22:34,566
have detected nothing.

427
00:22:35,833 --> 00:22:38,200
But the process constantly

428
00:22:38,200 --> 00:22:42,000
narrows down what
dark matter could possibly be.

429
00:22:43,166 --> 00:22:47,500
And currently,
LZ has time on its side.

430
00:22:47,500 --> 00:22:53,066
The plan is to accrue a total
of three years' worth of data.

431
00:22:54,466 --> 00:22:56,100
GHAG:
Hopefully, there'll be a
direct detection

432
00:22:56,100 --> 00:22:58,666
and we'll start
to understand the nature of it.

433
00:22:58,666 --> 00:23:00,633
It could be that dark matter
isn't a simple

434
00:23:00,633 --> 00:23:03,066
one-size-fits-all WIMP.

435
00:23:03,066 --> 00:23:05,266
It could be that there's
multiple different types

436
00:23:05,266 --> 00:23:07,166
of dark matter,
different species of the stuff,

437
00:23:07,166 --> 00:23:09,266
and we start to understand
the dark sector

438
00:23:09,266 --> 00:23:10,833
as more of a zoo.

439
00:23:10,833 --> 00:23:14,266
♪ ♪

440
00:23:14,266 --> 00:23:16,200
I'm deeply interested

441
00:23:16,200 --> 00:23:18,200
in trying to make some headway
into the unknown.

442
00:23:18,200 --> 00:23:21,166
So the bigger the unknown,
the better for me.

443
00:23:21,166 --> 00:23:24,133
So yeah, dark matter being
85% of the mass of the universe,

444
00:23:24,133 --> 00:23:28,766
that we have no real
clue about what this stuff is.

445
00:23:28,766 --> 00:23:31,400
But it is profoundly important.

446
00:23:31,400 --> 00:23:34,100
♪ ♪

447
00:23:35,100 --> 00:23:38,400
NARRATOR:
It's been a striking
transformation.

448
00:23:38,400 --> 00:23:42,366
In the past 50 years,
thanks to Vera Rubin and others,

449
00:23:42,366 --> 00:23:45,100
dark matter
has become an essential

450
00:23:45,100 --> 00:23:47,066
scientific building block

451
00:23:47,066 --> 00:23:52,200
at the foundation of our
understanding of the universe.

452
00:23:52,200 --> 00:23:55,100
There is no way out
of dark matter.

453
00:23:55,100 --> 00:23:58,733
If you believe in general
relativity and Newton's law,

454
00:23:58,733 --> 00:24:00,700
if you believe in that,

455
00:24:00,700 --> 00:24:03,733
no way out of dark matter;
you have to have dark matter.

456
00:24:09,766 --> 00:24:13,200
NARRATOR:
In 1998, as Voyager 1 traveled

457
00:24:13,200 --> 00:24:16,166
to the far reaches of our
solar system,

458
00:24:16,166 --> 00:24:19,200
it surpassed the record
of a previous space probe,

459
00:24:19,200 --> 00:24:23,333
Pioneer 10, as the most distant
human-made object.

460
00:24:23,333 --> 00:24:27,533
It was 6.5 billion miles
from Earth.

461
00:24:29,600 --> 00:24:31,833
1998 was also the year

462
00:24:31,833 --> 00:24:34,166
of one of
the greatest discoveries

463
00:24:34,166 --> 00:24:36,400
in the history of science.

464
00:24:36,400 --> 00:24:38,133
What seemed to be a force

465
00:24:38,133 --> 00:24:42,300
that literally creates
new space out of nothing.

466
00:24:43,533 --> 00:24:46,133
Today's issue of the journal
"Science" reports

467
00:24:46,133 --> 00:24:48,600
new information about
the evolution of the universe.

468
00:24:48,600 --> 00:24:50,466
A lead author
of one of the studies

469
00:24:50,466 --> 00:24:52,233
was cosmologist Adam Riess.

470
00:24:52,233 --> 00:24:54,133
Thanks for being with us.
Thank you.

471
00:24:54,133 --> 00:24:56,333
Why did some scientists
react with what one called

472
00:24:56,333 --> 00:24:58,600
"amazement and horror"
to these conclusions?

473
00:24:58,600 --> 00:25:00,200
Why was it such a shock to them?

474
00:25:00,200 --> 00:25:03,133
So we were hoping we'd find
a more simple explanation,

475
00:25:03,133 --> 00:25:06,066
something mundane, but...
But instead,

476
00:25:06,066 --> 00:25:08,633
you found a new force
in the universe?

477
00:25:08,633 --> 00:25:10,566
Well, it would appear that way.

478
00:25:10,566 --> 00:25:14,300
♪ ♪

479
00:25:14,300 --> 00:25:19,100
NARRATOR:
One of Baltimore's hidden gems
is the George Peabody Library

480
00:25:19,100 --> 00:25:22,166
at Johns Hopkins University.

481
00:25:22,166 --> 00:25:24,366
It has been called
"one of the most beautiful

482
00:25:24,366 --> 00:25:27,233
library spaces in the world."

483
00:25:28,400 --> 00:25:33,166
These five tiers
hold 300,000 volumes,

484
00:25:33,166 --> 00:25:38,100
including astronomical works
written over the centuries,

485
00:25:38,100 --> 00:25:41,633
that try to answer a question
that has troubled humankind

486
00:25:41,633 --> 00:25:43,100
perhaps always...

487
00:25:46,133 --> 00:25:48,733
...when we look up at
the night sky,

488
00:25:48,733 --> 00:25:52,233
what is it we are seeing?

489
00:25:52,233 --> 00:25:55,700
And has it been there forever?

490
00:25:55,700 --> 00:25:58,366
♪ ♪

491
00:25:58,366 --> 00:26:02,433
Adam Riess, an astrophysicist
from Johns Hopkins,

492
00:26:02,433 --> 00:26:04,533
played a key role in
formulating

493
00:26:04,533 --> 00:26:08,433
the current scientific answer
to that question.

494
00:26:10,133 --> 00:26:11,200
RIESS:
Wow.

495
00:26:11,200 --> 00:26:14,600
This is really the original
earth-centric model.

496
00:26:14,600 --> 00:26:16,433
NARRATOR:
Like many in astronomy,

497
00:26:16,433 --> 00:26:20,200
he has a deep appreciation
that he stands upon

498
00:26:20,200 --> 00:26:21,533
the shoulders of giants.

499
00:26:21,533 --> 00:26:23,233
This is really
my favorite here.

500
00:26:23,233 --> 00:26:27,700
Copernicus puts the sun
in the right place.

501
00:26:27,700 --> 00:26:29,633
This is progress in science.

502
00:26:31,833 --> 00:26:34,100
NARRATOR:
But Riess has also added to

503
00:26:34,100 --> 00:26:35,533
our understanding of
cosmology...

504
00:26:35,533 --> 00:26:37,100
(applause)

505
00:26:37,100 --> 00:26:39,100
...sharing a Nobel Prize in 2011

506
00:26:39,100 --> 00:26:42,833
with Saul Perlmutter
and Brian P. Schmidt,

507
00:26:42,833 --> 00:26:46,100
for a discovery
that profoundly changed

508
00:26:46,100 --> 00:26:48,166
our view of the universe.

509
00:26:48,166 --> 00:26:50,300
RIESS:
Here's somebody
after my own heart

510
00:26:50,300 --> 00:26:51,733
taking the observations,

511
00:26:51,733 --> 00:26:52,700
Tycho Brahe.

512
00:26:52,700 --> 00:26:55,433
NARRATOR:
Each of these influential
thinkers

513
00:26:55,433 --> 00:26:57,633
from prior to the
20th century

514
00:26:57,633 --> 00:27:00,600
have contributed to our
understanding of "the heavens."

515
00:27:00,600 --> 00:27:02,500
♪ ♪

516
00:27:02,500 --> 00:27:04,266
And here comes Isaac Newton,

517
00:27:04,266 --> 00:27:05,766
who really develops
the mathematics.

518
00:27:05,766 --> 00:27:09,800
And he really lays out
how gravity works.

519
00:27:09,800 --> 00:27:13,733
NARRATOR:
But they all shared
something in common--

520
00:27:13,733 --> 00:27:18,500
whatever the heavens were,
they seemed eternal.

521
00:27:18,500 --> 00:27:23,133
Earth may be at the center
surrounded by celestial spheres,

522
00:27:23,133 --> 00:27:25,300
or the sun
may be at the center

523
00:27:25,300 --> 00:27:27,833
with the planets orbiting it.

524
00:27:27,833 --> 00:27:32,066
Comets may come into view
and disappear,

525
00:27:32,066 --> 00:27:37,366
but all of these took place
on a gigantic but static stage.

526
00:27:37,366 --> 00:27:40,500
♪ ♪

527
00:27:40,500 --> 00:27:44,066
Even Albert Einstein
initially agreed.

528
00:27:45,266 --> 00:27:47,266
By the early 20th century,

529
00:27:47,266 --> 00:27:49,200
he had already revolutionized

530
00:27:49,200 --> 00:27:51,300
the Newtonian view of the world,

531
00:27:51,300 --> 00:27:56,066
by connecting space and time

532
00:27:56,066 --> 00:28:00,200
into one concept
he called space-time,

533
00:28:00,200 --> 00:28:03,066
and then theorizing
that gravity was

534
00:28:03,066 --> 00:28:07,300
the warping of that space-time
fabric by mass and energy.

535
00:28:08,800 --> 00:28:10,500
In 1917,

536
00:28:10,500 --> 00:28:14,766
he applied his new
ideas to the entire universe.

537
00:28:16,766 --> 00:28:19,800
But he already had
a final result in mind,

538
00:28:19,800 --> 00:28:23,000
the one generally accepted
by astronomers.

539
00:28:24,566 --> 00:28:26,066
Einstein's universe

540
00:28:26,066 --> 00:28:29,600
would be a largely static
and unchanging one,

541
00:28:29,600 --> 00:28:32,833
though gravity posed a problem.

542
00:28:32,833 --> 00:28:35,466
Einstein had kind of a
puzzle in his mind,

543
00:28:35,466 --> 00:28:37,833
because if the universe
was static,

544
00:28:37,833 --> 00:28:41,133
 
and yet all the matter in it
was attractive,

545
00:28:41,133 --> 00:28:43,200
gravity would
pull things together.

546
00:28:43,200 --> 00:28:45,100
How did it stay static?

547
00:28:45,100 --> 00:28:46,500
What kept it static?

548
00:28:46,500 --> 00:28:48,766
And he made
a remarkable discovery.

549
00:28:48,766 --> 00:28:51,833
In his theory
of general relativity,

550
00:28:51,833 --> 00:28:54,266
the gravity of matter
can be attractive,

551
00:28:54,266 --> 00:28:56,700
but that the gravity
of empty space

552
00:28:56,700 --> 00:28:57,633
could be repulsive.

553
00:28:57,633 --> 00:29:00,500
He called this
the cosmological constant,

554
00:29:00,500 --> 00:29:03,066
and he thought
it was a possibility

555
00:29:03,066 --> 00:29:04,766
that these
two kinds of gravities--

556
00:29:04,766 --> 00:29:06,366
the attractive
and the repulsive kind

557
00:29:06,366 --> 00:29:09,533
from two different
kinds of aspects of space--

558
00:29:09,533 --> 00:29:11,833
were causing
this kind of stalemate.

559
00:29:11,833 --> 00:29:15,233
♪ ♪

560
00:29:15,233 --> 00:29:18,466
NARRATOR:
Einstein's solution
didn't stand for long.

561
00:29:18,466 --> 00:29:21,733
And here,
at the Mount Wilson Observatory

562
00:29:21,733 --> 00:29:23,333
outside of Los Angeles,

563
00:29:23,333 --> 00:29:25,733
is where astronomers
gathered some of the data

564
00:29:25,733 --> 00:29:28,166
that led to its fall.

565
00:29:28,166 --> 00:29:29,833
♪ ♪

566
00:29:29,833 --> 00:29:32,133
These days,
you may be lucky enough

567
00:29:32,133 --> 00:29:34,100
to hear a
woodwind quintet playing

568
00:29:34,100 --> 00:29:35,166
in one of its storied domes--

569
00:29:35,166 --> 00:29:39,433
the acoustics are exceptional.

570
00:29:39,433 --> 00:29:44,833
(quintet performing)

571
00:29:44,833 --> 00:29:48,300
And it is an inspiring place

572
00:29:48,300 --> 00:29:50,200
for theoretical physicist

573
00:29:50,200 --> 00:29:53,133
and graphic nonfiction author
Clifford Johnson

574
00:29:53,133 --> 00:29:56,666
to let his mind explore.

575
00:29:56,666 --> 00:30:00,200
In the 1920s,
this observatory

576
00:30:00,200 --> 00:30:02,433
produced two of the
most important

577
00:30:02,433 --> 00:30:05,166
discoveries about
the nature of the universe...

578
00:30:05,166 --> 00:30:07,766
(quintet performing)

579
00:30:07,766 --> 00:30:11,533
...both by astronomer
Edwin Hubble--

580
00:30:11,533 --> 00:30:17,133
the same Hubble the famous
space telescope is named for.

581
00:30:17,133 --> 00:30:19,466
Hubble changes
our entire view of

582
00:30:19,466 --> 00:30:22,633
what the universe is
and how vast it is.

583
00:30:24,200 --> 00:30:27,733
NARRATOR:
At the time,
a debate raged in astronomy:

584
00:30:27,733 --> 00:30:31,566
was the Milky Way
the entire universe?

585
00:30:32,766 --> 00:30:35,033
Or was there more to
the story?

586
00:30:36,166 --> 00:30:38,300
In 1925,

587
00:30:38,300 --> 00:30:40,466
Hubble settled the issue

588
00:30:40,466 --> 00:30:43,266
by proving that
the Andromeda Nebula

589
00:30:43,266 --> 00:30:46,800
existed outside of
the Milky Way.

590
00:30:46,800 --> 00:30:50,166
It, along with
other distant nebulas,

591
00:30:50,166 --> 00:30:52,133
were renamed "galaxies."

592
00:30:52,133 --> 00:30:56,600
♪ ♪

593
00:30:56,600 --> 00:30:58,633
DE SWART:
The whole notion of a "galaxy"

594
00:30:58,633 --> 00:31:02,433
started to become a thing
only in the mid-1920s.

595
00:31:02,433 --> 00:31:04,733
People started immediately
get interested

596
00:31:04,733 --> 00:31:06,000
in what these things are.

597
00:31:08,333 --> 00:31:10,700
NARRATOR:
Especially Edwin Hubble.

598
00:31:10,700 --> 00:31:13,133
He began measuring
the distance from Earth

599
00:31:13,133 --> 00:31:15,833
to various galaxies,

600
00:31:15,833 --> 00:31:18,200
and when he combined
his work with

601
00:31:18,200 --> 00:31:19,533
that of
other astronomers,

602
00:31:19,533 --> 00:31:23,133
he discovered something
deeply mysterious.

603
00:31:23,133 --> 00:31:26,366
It had to do with
the Doppler effect.

604
00:31:26,366 --> 00:31:28,100
(distorted pitch shifting)

605
00:31:29,333 --> 00:31:31,266
We typically think of
the Doppler effect

606
00:31:31,266 --> 00:31:33,700
in terms of sound.

607
00:31:33,700 --> 00:31:37,366
A siren coming toward you
has a higher pitch,

608
00:31:37,366 --> 00:31:39,266
because the sound waves
catch up to each other

609
00:31:39,266 --> 00:31:42,066
and become compressed.

610
00:31:42,066 --> 00:31:45,633
A siren heading away from you
sounds lower,

611
00:31:45,633 --> 00:31:48,100
because the sound waves
stretch out.

612
00:31:48,100 --> 00:31:50,300
♪ ♪

613
00:31:50,300 --> 00:31:53,433
A similar thing happens
with light waves--

614
00:31:53,433 --> 00:31:56,833
if the source of light
is headed toward the observer,

615
00:31:56,833 --> 00:32:00,300
the light it emits will be
shifted toward blue.

616
00:32:00,300 --> 00:32:02,566
If the source is
moving away,

617
00:32:02,566 --> 00:32:05,200
the light is
shifted toward red.

618
00:32:05,200 --> 00:32:06,666
(film reel ticking)

619
00:32:06,666 --> 00:32:08,566
In fact,

620
00:32:08,566 --> 00:32:10,233
astronomers
working parallel to Hubble

621
00:32:10,233 --> 00:32:12,733
encountered exactly that.

622
00:32:14,633 --> 00:32:16,066
The light coming from

623
00:32:16,066 --> 00:32:18,533
almost every galaxy
they observed

624
00:32:18,533 --> 00:32:21,133
was shifted toward red,

625
00:32:21,133 --> 00:32:22,833
indicating the galaxies were

626
00:32:22,833 --> 00:32:25,000
moving away from Earth.

627
00:32:26,166 --> 00:32:28,266
And when Hubble checked
the redshifts

628
00:32:28,266 --> 00:32:31,200
against his own
distance measurements,

629
00:32:31,200 --> 00:32:33,266
he discovered not only
were the galaxies

630
00:32:33,266 --> 00:32:35,200
racing away from us,

631
00:32:35,200 --> 00:32:40,366
but the ones farther away
were racing away faster!

632
00:32:40,366 --> 00:32:43,766
What did that mean?

633
00:32:43,766 --> 00:32:45,333
CLIFFORD JOHNSON:
Given that we're not in a

634
00:32:45,333 --> 00:32:47,266
special place in the universe,

635
00:32:47,266 --> 00:32:49,133
we're not at the center of
the universe,

636
00:32:49,133 --> 00:32:50,600
the conclusion is, is that

637
00:32:50,600 --> 00:32:52,633
the whole universe
is expanding.

638
00:32:52,633 --> 00:32:55,066
Everything is moving away
from everything else.

639
00:32:55,066 --> 00:32:58,666
This is
another huge discovery

640
00:32:58,666 --> 00:33:00,333
about the nature of our
universe.

641
00:33:00,333 --> 00:33:05,333
♪ ♪

642
00:33:05,333 --> 00:33:06,766
NARRATOR:
Some astronomers,

643
00:33:06,766 --> 00:33:07,633
like Belgian cosmologist

644
00:33:07,633 --> 00:33:11,066
and Catholic priest
Georges Lemaître,

645
00:33:11,066 --> 00:33:13,733
were already
exploring the implications

646
00:33:13,733 --> 00:33:15,433
of an expanding universe.

647
00:33:15,433 --> 00:33:20,700
If you rewind the expansion,
like a film,

648
00:33:20,700 --> 00:33:23,766
where does the universe
"start"?

649
00:33:23,766 --> 00:33:25,666
Does it have a beginning?

650
00:33:25,666 --> 00:33:29,733
♪ ♪

651
00:33:29,733 --> 00:33:31,466
The idea
is that there was

652
00:33:31,466 --> 00:33:33,800
some earlier phase
in the universe

653
00:33:33,800 --> 00:33:36,600
where everything
was much closer together.

654
00:33:36,600 --> 00:33:41,533
Some very dense early phase
of the universe.

655
00:33:41,533 --> 00:33:45,533
And something happened
to begin to push things apart.

656
00:33:47,133 --> 00:33:49,766
(explosion booming)

657
00:33:49,766 --> 00:33:52,366
That line of thinking
led to the theory

658
00:33:52,366 --> 00:33:56,800
labeled by its detractors
as "The Big Bang."

659
00:33:56,800 --> 00:34:01,133
♪ ♪

660
00:34:01,133 --> 00:34:05,200
(explosion echoing)

661
00:34:11,133 --> 00:34:13,233
It wasn't until the mid-1960s

662
00:34:13,233 --> 00:34:17,700
that observational evidence
quieted the Big Bang critics,

663
00:34:17,700 --> 00:34:20,566
when two astronomers,

664
00:34:20,566 --> 00:34:23,066
Robert Wilson
and Arno Penzias,

665
00:34:23,066 --> 00:34:26,233
using this antenna
in Holmdel, New Jersey,

666
00:34:26,233 --> 00:34:30,566
stumbled across one of its
predicted artifacts.

667
00:34:30,566 --> 00:34:32,766
After the Big Bang,

668
00:34:32,766 --> 00:34:35,066
it took hundreds
of thousands of years

669
00:34:35,066 --> 00:34:37,233
for the universe to cool enough

670
00:34:37,233 --> 00:34:39,400
to transmit light.

671
00:34:39,400 --> 00:34:44,166
That initial burst has left
a faint residual glow.

672
00:34:44,166 --> 00:34:48,700
Today, we call it the
Cosmic Microwave Background,

673
00:34:48,700 --> 00:34:51,366
or CMB.

674
00:34:51,366 --> 00:34:53,200
The Cosmic Microwave
Background

675
00:34:53,200 --> 00:34:56,300
is actually a remnant
of the Big Bang.

676
00:34:56,300 --> 00:34:58,066
It's the radiation

677
00:34:58,066 --> 00:35:02,400
from that Big Bang
that we can observe

678
00:35:02,400 --> 00:35:06,700
from when the universe
was about 380,000 years old.

679
00:35:08,533 --> 00:35:11,133
NARRATOR:
Later, ground- and space-based
experiments

680
00:35:11,133 --> 00:35:13,266
would study this
"fossil radiation"

681
00:35:13,266 --> 00:35:16,733
in ever-finer detail,

682
00:35:16,733 --> 00:35:19,766
because its extremely
slight variations,

683
00:35:19,766 --> 00:35:22,066
shown here
in different colors,

684
00:35:22,066 --> 00:35:25,133
can reveal insights
into the structure

685
00:35:25,133 --> 00:35:26,333
of the early universe.

686
00:35:29,466 --> 00:35:33,200
By the 1970s,
thanks to the CMB,

687
00:35:33,200 --> 00:35:36,100
most astronomers had accepted
the Big Bang theory

688
00:35:36,100 --> 00:35:40,233
and that the universe
was expanding,

689
00:35:40,233 --> 00:35:43,333
but they also thought the
expansion was likely slowing

690
00:35:43,333 --> 00:35:49,066
because of the attractive force
of gravity on matter.

691
00:35:49,066 --> 00:35:51,266
RIESS:
Matter decelerates the
expansion.

692
00:35:51,266 --> 00:35:53,333
It decelerates it either
a little bit

693
00:35:53,333 --> 00:35:54,666
if there's only
a little matter

694
00:35:54,666 --> 00:35:56,633
and the universe
expands forever,

695
00:35:56,633 --> 00:35:58,666
or it decelerates it
a great deal,

696
00:35:58,666 --> 00:36:00,200
halting the expansion

697
00:36:00,200 --> 00:36:01,400
at some point in the future

698
00:36:01,400 --> 00:36:03,566
and causing
the universe to collapse.

699
00:36:03,566 --> 00:36:06,133
(echoing boom)

700
00:36:06,133 --> 00:36:09,533
NARRATOR:
Measuring how fast the expansion
was decelerating

701
00:36:09,533 --> 00:36:12,766
would reveal the fate
of the universe.

702
00:36:12,766 --> 00:36:14,366
(echoing boom)

703
00:36:14,366 --> 00:36:18,333
And the key to doing that
was this.

704
00:36:18,333 --> 00:36:24,066
♪ ♪

705
00:36:24,066 --> 00:36:28,766
One of the brightest
explosions observed in space;

706
00:36:28,766 --> 00:36:33,433
when a star
becomes a supernova.

707
00:36:34,500 --> 00:36:37,100
There are
two types of supernovas

708
00:36:37,100 --> 00:36:39,600
and distinctions within those,

709
00:36:39,600 --> 00:36:44,466
but a Type Ia supernova
is fairly common.

710
00:36:44,466 --> 00:36:47,666
About a quarter of all
supernovas,

711
00:36:47,666 --> 00:36:50,300
incredibly bright--

712
00:36:50,300 --> 00:36:54,200
sometimes brighter than
an entire galaxy...

713
00:36:54,200 --> 00:36:55,500
(echoing boom)

714
00:36:55,500 --> 00:36:59,466
...and remarkably consistent.

715
00:36:59,466 --> 00:37:01,733
That makes it
an excellent candidate

716
00:37:01,733 --> 00:37:06,366
to be what astronomers call
"a standard candle."

717
00:37:06,366 --> 00:37:09,100
A kind of
cosmic measuring stick...

718
00:37:10,533 --> 00:37:13,466
...if enough of them
could be found.

719
00:37:14,800 --> 00:37:15,900
So, that was the goal

720
00:37:15,900 --> 00:37:20,300
of the newly formed
High-Z Supernova Search Team.

721
00:37:20,300 --> 00:37:22,233
Adam Riess was a member.

722
00:37:22,233 --> 00:37:23,233
All the way from HP...

723
00:37:23,233 --> 00:37:25,466
NARRATOR:
They planned to discover

724
00:37:25,466 --> 00:37:28,200
distant Type Ia supernovas,

725
00:37:28,200 --> 00:37:31,500
compare them to nearby ones,

726
00:37:31,500 --> 00:37:33,300
and definitively answer

727
00:37:33,300 --> 00:37:37,333
how much the expansion of the
universe was slowing down.

728
00:37:37,333 --> 00:37:39,133
But they weren't alone.

729
00:37:39,133 --> 00:37:41,766
There was another team,
the Supernova Cosmology Project,

730
00:37:41,766 --> 00:37:44,200
which had started
a number of years before us.

731
00:37:44,200 --> 00:37:46,133
They were more particle
physicists,

732
00:37:46,133 --> 00:37:47,300
and we were more,

733
00:37:47,300 --> 00:37:49,366
I would say,
supernova astronomers.

734
00:37:49,366 --> 00:37:51,100
♪ ♪

735
00:37:51,100 --> 00:37:52,766
But both competing,
realistically,

736
00:37:52,766 --> 00:37:55,100
for the same
telescope facilities,

737
00:37:55,100 --> 00:37:56,733
which were very precious
commodities

738
00:37:56,733 --> 00:37:57,833
to get to do
this research.

739
00:37:57,833 --> 00:38:00,166
NARRATOR:
By 1997,

740
00:38:00,166 --> 00:38:02,733
the High-Z team
had collected

741
00:38:02,733 --> 00:38:04,733
a large enough sample of
supernovas

742
00:38:04,733 --> 00:38:09,133
to get a "first read"
on the universe.

743
00:38:09,133 --> 00:38:10,266
Hey, look at that!

744
00:38:10,266 --> 00:38:13,166
NARRATOR:
But initially,
the results made no sense.

745
00:38:14,533 --> 00:38:16,200
So we went from saying,
you know,

746
00:38:16,200 --> 00:38:17,833
"this has gotta be wrong,"
to like,

747
00:38:17,833 --> 00:38:19,766
"this looks like
what the data says,

748
00:38:19,766 --> 00:38:21,100
We have to report that."

749
00:38:23,633 --> 00:38:26,266
NARRATOR:
In early 1998,

750
00:38:26,266 --> 00:38:31,066
both teams announced
the same shocking conclusion:

751
00:38:31,066 --> 00:38:35,733
the universe was not
slowing in its expansion,

752
00:38:35,733 --> 00:38:39,400
it was speeding up.

753
00:38:39,400 --> 00:38:41,366
Like an invisible hand,

754
00:38:41,366 --> 00:38:46,066
some undiscovered force was
at war with gravity

755
00:38:46,066 --> 00:38:48,833
and pushing the universe apart

756
00:38:48,833 --> 00:38:51,733
faster and faster.

757
00:38:51,733 --> 00:38:54,133
♪ ♪

758
00:38:54,133 --> 00:38:55,433
RIESS:
From what we can see,

759
00:38:55,433 --> 00:38:56,733
there's really not too much left

760
00:38:56,733 --> 00:38:58,566
beside the possibility of
this repulsive force.

761
00:38:58,566 --> 00:39:00,133
Does that mean that
the universe

762
00:39:00,133 --> 00:39:01,633
could just keep on
expanding forever?

763
00:39:01,633 --> 00:39:04,100
If you take this result
at face value,

764
00:39:04,100 --> 00:39:06,066
if this is really true,
the implication is

765
00:39:06,066 --> 00:39:07,666
yes, that the universe
would expand forever.

766
00:39:07,666 --> 00:39:10,666
♪ ♪

767
00:39:10,666 --> 00:39:13,133
NARRATOR:
The mysterious repulsive force

768
00:39:13,133 --> 00:39:15,166
came to be known

769
00:39:15,166 --> 00:39:18,533
as "dark energy."

770
00:39:18,533 --> 00:39:20,800
"Dark energy" is really the name
we give to our ignorance

771
00:39:20,800 --> 00:39:21,733
of what's causing

772
00:39:21,733 --> 00:39:24,666
the accelerating expansion
of the universe.

773
00:39:24,666 --> 00:39:28,200
It's a pushing out
that it does.

774
00:39:28,200 --> 00:39:30,800
It's a pressure,
an outward pressure,

775
00:39:30,800 --> 00:39:32,666
that the gravitational force
is pushing against.

776
00:39:32,666 --> 00:39:34,366
♪ ♪

777
00:39:34,366 --> 00:39:36,833
Overall, the universe is

778
00:39:36,833 --> 00:39:39,666
accelerating in its expansion

779
00:39:39,666 --> 00:39:41,766
because of this
dark energy effect.

780
00:39:41,766 --> 00:39:44,433
♪ ♪

781
00:39:44,433 --> 00:39:48,133
NARRATOR:
Today, scientists estimate
it is overwhelmingly

782
00:39:48,133 --> 00:39:52,100
the most prevalent form of
energy in the universe.

783
00:39:52,100 --> 00:39:53,100
RHODES:
We thought we knew

784
00:39:53,100 --> 00:39:54,833
the constituents of the universe

785
00:39:54,833 --> 00:39:56,266
and how it was evolving
over time.

786
00:39:56,266 --> 00:39:58,133
Al of a sudden,
we found out

787
00:39:58,133 --> 00:39:59,133
that, no,
we didn't know,

788
00:39:59,133 --> 00:40:01,533
because the biggest
component of the universe

789
00:40:01,533 --> 00:40:04,100
wasn't dark matter,
it was dark energy.

790
00:40:06,666 --> 00:40:10,800
NARRATOR:
So, what exactly is
dark energy?

791
00:40:10,800 --> 00:40:14,200
One of the simplest ideas
is that it's actually

792
00:40:14,200 --> 00:40:16,766
a property of
space and time itself.

793
00:40:16,766 --> 00:40:19,800
NARRATOR:
Scientists had always assumed

794
00:40:19,800 --> 00:40:24,133
the energy level of
a perfect vacuum was zero.

795
00:40:24,133 --> 00:40:25,766
But what if it wasn't?

796
00:40:25,766 --> 00:40:31,066
What if, as the universe
expanded and created more space,

797
00:40:31,066 --> 00:40:34,600
a repulsive energy
inherent to that space

798
00:40:34,600 --> 00:40:37,200
grew as well?

799
00:40:37,200 --> 00:40:39,700
On massive scales,
it would oppose

800
00:40:39,700 --> 00:40:41,600
and maybe even overcome

801
00:40:41,600 --> 00:40:44,100
the gravitational
attraction of matter.

802
00:40:46,100 --> 00:40:47,300
CLIFFORD JOHNSON:
And ironically,

803
00:40:47,300 --> 00:40:48,666
that's exactly
the kind of thing

804
00:40:48,666 --> 00:40:51,333
that Einstein had
come up with long ago,

805
00:40:51,333 --> 00:40:53,033
when he was trying to make
the universe static.

806
00:40:54,066 --> 00:40:57,200
NARRATOR:
In his formula to describe
the universe,

807
00:40:57,200 --> 00:41:00,433
Einstein had added
a "cosmological constant"

808
00:41:00,433 --> 00:41:04,466
to perfectly balance
the attractive effect of gravity

809
00:41:04,466 --> 00:41:08,200
and create his
"static" universe.

810
00:41:08,200 --> 00:41:09,066
(booming)

811
00:41:09,066 --> 00:41:11,800
When astronomers
in the 1920s and '30s

812
00:41:11,800 --> 00:41:15,233
concluded that the universe
wasn't static at all,

813
00:41:15,233 --> 00:41:16,800
but expanding,

814
00:41:16,800 --> 00:41:19,566
he dropped
his cosmological constant,

815
00:41:19,566 --> 00:41:23,233
and is said to have called it
his "biggest blunder."

816
00:41:23,233 --> 00:41:27,166
But with the discovery
of an accelerating expansion,

817
00:41:27,166 --> 00:41:30,666
cosmologists
revived the term.

818
00:41:30,666 --> 00:41:33,133
In fact, it was an idea

819
00:41:33,133 --> 00:41:36,100
Adam Riess turned to
early in his analysis.

820
00:41:37,400 --> 00:41:39,833
After convincing myself
I hadn't made a mistake,

821
00:41:39,833 --> 00:41:42,833
I introduced that possibility
into the analysis

822
00:41:42,833 --> 00:41:46,066
that Einstein's
cosmological constant existed,

823
00:41:46,066 --> 00:41:48,166
and the fit grabbed onto it
and said, "Yes, this--"

824
00:41:48,166 --> 00:41:50,066
you know, with
pretty high confidence--

825
00:41:50,066 --> 00:41:53,233
"this is indeed part of
the recipe of the universe."

826
00:41:54,666 --> 00:41:56,833
NARRATOR:
So how did astronomers miss

827
00:41:56,833 --> 00:42:00,200
this most consequential
of phenomena?

828
00:42:00,200 --> 00:42:03,700
CLIFFORD JOHNSON:
Perhaps the reason we hadn't
noticed it before

829
00:42:03,700 --> 00:42:06,266
is because the way you measure
it is in terms of

830
00:42:06,266 --> 00:42:10,466
how much is it per unit
of space time.

831
00:42:10,466 --> 00:42:14,200
Perhaps a little chunk
of space right here.

832
00:42:14,200 --> 00:42:17,233
So you have to divide
the entire effect

833
00:42:17,233 --> 00:42:19,166
by the volume of
the observable universe.

834
00:42:19,166 --> 00:42:21,266
So that makes it
a very small number.

835
00:42:21,266 --> 00:42:24,133
NARRATOR:
Imagine the energy released

836
00:42:24,133 --> 00:42:25,266
by a match head burning.

837
00:42:25,266 --> 00:42:28,700
(hissing, flame roaring)

838
00:42:28,700 --> 00:42:31,566
The estimated equivalent
in dark energy

839
00:42:31,566 --> 00:42:35,100
is spread across
a cube of empty space

840
00:42:35,100 --> 00:42:39,100
with an edge about
seven and a half miles long--

841
00:42:39,100 --> 00:42:42,133
or the amount of space
contained by

842
00:42:42,133 --> 00:42:45,166
about one and half million
Astrodomes.

843
00:42:45,166 --> 00:42:46,766
♪ ♪

844
00:42:46,766 --> 00:42:49,066
So it's small--

845
00:42:49,066 --> 00:42:51,133
and maybe in the early history
of the universe,

846
00:42:51,133 --> 00:42:54,333
when it contained
a lot less empty space,

847
00:42:54,333 --> 00:42:56,300
not even that important.

848
00:42:56,300 --> 00:42:57,733
KIESSLING:
If we were in

849
00:42:57,733 --> 00:42:59,733
a period of time much,
much earlier

850
00:42:59,733 --> 00:43:02,166
in the history of the universe,
dark energy was

851
00:43:02,166 --> 00:43:04,566
 
a very, very small
component of the universe,

852
00:43:04,566 --> 00:43:06,833
and it wouldn't have
necessarily been noticeable.

853
00:43:06,833 --> 00:43:09,133
(booming)

854
00:43:09,133 --> 00:43:12,833
NARRATOR:
But that changed about
six billion years ago.

855
00:43:12,833 --> 00:43:15,633
By then, the universe
had grown big enough

856
00:43:15,633 --> 00:43:19,833
for dark energy to overcome
the attractive force of gravity

857
00:43:19,833 --> 00:43:23,833
and start speeding up
the expansion.

858
00:43:23,833 --> 00:43:28,433
Today, dark energy
dominates the universe,

859
00:43:28,433 --> 00:43:33,266
and it may even determine
its ultimate fate.

860
00:43:33,266 --> 00:43:35,833
KÖNIG:
Now we are in the
dark energy era

861
00:43:35,833 --> 00:43:39,566
of the universe, which means
that the universe is

862
00:43:39,566 --> 00:43:42,700
expanding at
an accelerated rate.

863
00:43:42,700 --> 00:43:45,066
If the universe would
keep on expanding

864
00:43:45,066 --> 00:43:46,400
and expanding and expanding...

865
00:43:46,400 --> 00:43:48,066
Then we seem to be looking at

866
00:43:48,066 --> 00:43:49,800
a far distant future

867
00:43:49,800 --> 00:43:52,233
in which the universe
is basically empty.

868
00:43:52,233 --> 00:43:54,433
It's been diluted

869
00:43:54,433 --> 00:43:56,433
of all the other stuff
that we otherwise can see

870
00:43:56,433 --> 00:43:58,366
lighting up
and dancing around us.

871
00:43:58,366 --> 00:44:00,133
Galaxies will just continue

872
00:44:00,133 --> 00:44:01,633
moving further and further
apart from each other.

873
00:44:01,633 --> 00:44:03,533
♪ ♪

874
00:44:03,533 --> 00:44:08,466
DE SWART:
Our nearest galaxies will
go beyond our visible horizon,

875
00:44:08,466 --> 00:44:11,100
beyond what we can see
in the universe.

876
00:44:11,100 --> 00:44:13,566
KAISER:
Space would stretch
even faster than light could

877
00:44:13,566 --> 00:44:16,466
catch up to tell us
there's a galaxy over there.

878
00:44:16,466 --> 00:44:18,600
KÖNIG
Eventually, we will not be
able to see the light

879
00:44:18,600 --> 00:44:21,133
coming from
another galaxy.

880
00:44:21,133 --> 00:44:24,100
DE SWART:
We can't see any other
galaxy anymore

881
00:44:24,100 --> 00:44:26,766
because dark energy and
the expansion of the universe

882
00:44:26,766 --> 00:44:28,833
has driven this all away.

883
00:44:28,833 --> 00:44:30,366
That would be kind of sad.

884
00:44:30,366 --> 00:44:33,800
We might not be
sort of torn apart,

885
00:44:33,800 --> 00:44:37,066
we just become extremely,
extremely lonely.

886
00:44:37,066 --> 00:44:39,433
The end of the universe
will be very cold

887
00:44:39,433 --> 00:44:42,200
and very dark, and...

888
00:44:42,200 --> 00:44:43,466
and we won't see

889
00:44:43,466 --> 00:44:45,233
the nearby galaxies and so on.

890
00:44:45,233 --> 00:44:47,133
That's the future expansion
of the universe.

891
00:44:47,133 --> 00:44:50,100
♪ ♪

892
00:44:50,100 --> 00:44:52,566
NARRATOR:
If it makes anyone feel better,

893
00:44:52,566 --> 00:44:55,733
there is still a lot of
uncertainty about dark energy,

894
00:44:55,733 --> 00:45:00,200
especially whether it has been
consistent over time.

895
00:45:00,200 --> 00:45:01,566
KIESSLING:
At the moment,

896
00:45:01,566 --> 00:45:02,800
we think it's been consistent,

897
00:45:02,800 --> 00:45:04,366
but it's potentially
Nobel Prize-winning

898
00:45:04,366 --> 00:45:06,233
if it's been
changing over time,

899
00:45:06,233 --> 00:45:08,500
and so secretly--
not-so secretly--

900
00:45:08,500 --> 00:45:10,133
(laughing):
cosmologists are really hoping

901
00:45:10,133 --> 00:45:12,066
to find something different,

902
00:45:12,066 --> 00:45:13,833
because that'll be
really exciting.

903
00:45:13,833 --> 00:45:16,400
♪ ♪

904
00:45:16,400 --> 00:45:19,666
NARRATOR:
A "cosmological constant"
that isn't really constant

905
00:45:19,666 --> 00:45:23,333
could be the solution to
another vexing mystery,

906
00:45:23,333 --> 00:45:27,300
which some have called
a "cosmological crisis."

907
00:45:27,300 --> 00:45:29,366
This is a real problem.

908
00:45:29,366 --> 00:45:31,200
There's some tensions
in what we are seeing.

909
00:45:31,200 --> 00:45:34,733
This has been a great challenge
for us in the last ten years.

910
00:45:34,733 --> 00:45:37,100
This is something that
can't just be wished away.

911
00:45:37,100 --> 00:45:38,600
(booming)

912
00:45:38,600 --> 00:45:40,266
NARRATOR:
It has to do with how fast
the universe

913
00:45:40,266 --> 00:45:42,466
is currently expanding;

914
00:45:42,466 --> 00:45:45,833
that's known as
the "Hubble constant."

915
00:45:45,833 --> 00:45:46,966
To calculate it,

916
00:45:46,966 --> 00:45:50,700
scientists have mainly used
two different approaches.

917
00:45:50,700 --> 00:45:54,500
One is based on the
"baby picture" of the universe--

918
00:45:54,500 --> 00:45:56,300
the CMB--

919
00:45:56,300 --> 00:45:58,433
which itself
has been measured

920
00:45:58,433 --> 00:46:00,466
in ever-increasing detail.

921
00:46:00,466 --> 00:46:01,700
KAISER:
Three different generations

922
00:46:01,700 --> 00:46:03,666
of specially built
satellites in the sky

923
00:46:03,666 --> 00:46:05,366
to just do this
one thing:

924
00:46:05,366 --> 00:46:08,333
measure the CMB, to my mind,
mind-boggling precision.

925
00:46:08,333 --> 00:46:09,766
AMON:
The measurements that we have

926
00:46:09,766 --> 00:46:11,766
from the cosmic microwave
background right now,

927
00:46:11,766 --> 00:46:13,766
they are the gold standard
in our field,

928
00:46:13,766 --> 00:46:17,366
so high-quality that when
you make measurements from it,

929
00:46:17,366 --> 00:46:19,533
they are extremely
high precision.

930
00:46:21,066 --> 00:46:22,533
NARRATOR:
Meanwhile, other groups,

931
00:46:22,533 --> 00:46:24,166
including one led by
Adam Riess,

932
00:46:24,166 --> 00:46:27,066
have calculated
the Hubble Constant

933
00:46:27,066 --> 00:46:30,200
using measurements
of distant supernovas.

934
00:46:30,200 --> 00:46:33,366
(booming)

935
00:46:33,366 --> 00:46:36,133
KAISER:
Distant things from us,
but not nearly so distant

936
00:46:36,133 --> 00:46:37,400
as the cosmic microwave
background,

937
00:46:37,400 --> 00:46:39,833
phenomena that are old
in cosmic history,

938
00:46:39,833 --> 00:46:40,833
but not quite so old.

939
00:46:40,833 --> 00:46:42,200
We call them "late universe."

940
00:46:43,433 --> 00:46:45,700
NARRATOR:
Two different techniques--

941
00:46:45,700 --> 00:46:48,833
one based on the early universe,
the CMB--

942
00:46:48,833 --> 00:46:51,600
and the other
on the "late universe,"

943
00:46:51,600 --> 00:46:53,100
using supernovas.

944
00:46:53,966 --> 00:46:57,266
We have the ability to
bookend the universe.

945
00:46:57,266 --> 00:46:59,100
 
To essentially see
how fast the universe

946
00:46:59,100 --> 00:47:00,800
was expanding
at the beginning,

947
00:47:00,800 --> 00:47:02,800
and how fast
it's expanding now.

948
00:47:02,800 --> 00:47:04,466
We're measuring the same
universe,

949
00:47:04,466 --> 00:47:07,133
whether we're measuring
the cosmic microwave background

950
00:47:07,133 --> 00:47:08,066
or a population of supernovae.

951
00:47:08,066 --> 00:47:10,400
To see if you can go from
one to the other.

952
00:47:10,400 --> 00:47:12,066
If you can predict
how fast the universe

953
00:47:12,066 --> 00:47:13,333
ought to be expanding.

954
00:47:13,333 --> 00:47:15,500
And there's all kinds of reasons
to think that

955
00:47:15,500 --> 00:47:17,766
either one of these kinds
of physical systems

956
00:47:17,766 --> 00:47:18,800
should give the same answer.

957
00:47:18,800 --> 00:47:21,400
It essentially lets us test
our standard model

958
00:47:21,400 --> 00:47:22,833
over cosmic time.

959
00:47:22,833 --> 00:47:27,566
And that sets up a very
beautiful robustness test

960
00:47:27,566 --> 00:47:29,166
for "does this model work?"

961
00:47:30,666 --> 00:47:33,833
NARRATOR:
But as the accuracy of
each approach has grown,

962
00:47:33,833 --> 00:47:36,100
the estimates for
the Hubble constant--

963
00:47:36,100 --> 00:47:39,066
the speed the universe is
expanding--

964
00:47:39,066 --> 00:47:41,300
have diverged,

965
00:47:41,300 --> 00:47:44,466
a problem known as
the "Hubble Tension."

966
00:47:44,466 --> 00:47:48,166
RIESS:
Many of us are quite fascinated
by the implication

967
00:47:48,166 --> 00:47:50,100
that we could be
missing something still

968
00:47:50,100 --> 00:47:51,666
in our understanding
of the universe.

969
00:47:51,666 --> 00:47:54,066
Or this might be
another clue

970
00:47:54,066 --> 00:47:55,833
about the nature of some
of these unknown

971
00:47:55,833 --> 00:47:58,100
parts of the universe,
the dark matter,

972
00:47:58,100 --> 00:47:59,533
the dark energy,
things like that.

973
00:47:59,533 --> 00:48:01,100
When we get mismatches,

974
00:48:01,100 --> 00:48:03,066
we get pretty excited
about it in our field,

975
00:48:03,066 --> 00:48:05,833
because these
"tensions" tell us that

976
00:48:05,833 --> 00:48:08,166
maybe something is
not quite right in the model.

977
00:48:08,166 --> 00:48:10,333
Maybe that's the hint
of where to look

978
00:48:10,333 --> 00:48:12,200
for the next breakthrough.

979
00:48:12,200 --> 00:48:14,600
This is where we find
new physics.

980
00:48:14,600 --> 00:48:16,166
This is where we find discovery.

981
00:48:16,166 --> 00:48:19,066
Is it just measurements
being made wrong?

982
00:48:19,066 --> 00:48:22,100
Is it modeling
being made wrong?

983
00:48:22,100 --> 00:48:24,133
Or are we fundamentally
not understanding

984
00:48:24,133 --> 00:48:26,066
something about our universe?

985
00:48:26,066 --> 00:48:27,233
We don't know yet.

986
00:48:27,233 --> 00:48:28,700
But it's telling us
that cosmology

987
00:48:28,700 --> 00:48:30,466
is still very exciting.

988
00:48:30,466 --> 00:48:32,166
MAN (on radio):
Four, three,

989
00:48:32,166 --> 00:48:34,466
two, one, lift off.

990
00:48:34,466 --> 00:48:36,566
(rocket engine roaring)

991
00:48:36,566 --> 00:48:38,833
NARRATOR:
So, the jury is still out,

992
00:48:38,833 --> 00:48:41,300
but more data is on the way.

993
00:48:42,266 --> 00:48:46,066
The European Space Agency's
Euclid space telescope

994
00:48:46,066 --> 00:48:50,133
launched on July 1, 2023.

995
00:48:50,133 --> 00:48:54,233
It's designed to look
ten billion years into the past

996
00:48:54,233 --> 00:48:56,800
with unprecedented accuracy.

997
00:48:56,800 --> 00:48:58,833
♪ ♪

998
00:48:58,833 --> 00:49:02,133
And Euclid is not alone
in its pursuit of answers.

999
00:49:04,133 --> 00:49:06,433
It will soon be joined by

1000
00:49:06,433 --> 00:49:09,366
NASA's Nancy Grace
Roman Space Telescope,

1001
00:49:09,366 --> 00:49:12,733
which will measure
distances and positions

1002
00:49:12,733 --> 00:49:15,400
for millions of galaxies.

1003
00:49:18,233 --> 00:49:21,800
But perhaps most fitting
will be the work done here,

1004
00:49:21,800 --> 00:49:23,766
in the soon-to-be completed

1005
00:49:23,766 --> 00:49:27,266
Vera C. Rubin Observatory,
in Chile.

1006
00:49:29,233 --> 00:49:33,100
It will house the
Simonyi Survey Telescope

1007
00:49:33,100 --> 00:49:36,266
that will photograph
the entire night sky

1008
00:49:36,266 --> 00:49:37,700
every few nights

1009
00:49:37,700 --> 00:49:42,166
using the largest digital camera
ever constructed.

1010
00:49:43,233 --> 00:49:45,200
WECHSLER:
I think it's wonderful

1011
00:49:45,200 --> 00:49:47,233
that the Vera C. Rubin
Observatory

1012
00:49:47,233 --> 00:49:49,100
has been named after
Vera Rubin.

1013
00:49:49,100 --> 00:49:52,533
She was fearless
and undaunted.

1014
00:49:52,533 --> 00:49:54,366
She just kept going.

1015
00:49:54,366 --> 00:49:58,166
My number one belief is that
the universe is for everyone.

1016
00:49:58,166 --> 00:50:01,100
We all have this right
to understand

1017
00:50:01,100 --> 00:50:02,700
our place
in the universe

1018
00:50:02,700 --> 00:50:04,400
and how the universe works.

1019
00:50:04,400 --> 00:50:08,033
And I think that's really
a fitting part of her legacy.

1020
00:50:10,066 --> 00:50:13,066
♪ ♪

1021
00:50:13,066 --> 00:50:17,200
NARRATOR:
In 2012,
Voyager 1 left our solar system

1022
00:50:17,200 --> 00:50:19,433
and the sun's
protective heliosphere,

1023
00:50:19,433 --> 00:50:23,066
sending home the
first direct observations

1024
00:50:23,066 --> 00:50:25,300
of interstellar space.

1025
00:50:27,400 --> 00:50:30,300
Today, the space probe
continues

1026
00:50:30,300 --> 00:50:33,500
on its lonely journey,

1027
00:50:33,500 --> 00:50:35,733
as it likely will

1028
00:50:35,733 --> 00:50:38,766
long after we're gone.

1029
00:50:38,766 --> 00:50:39,633
(clicking)

1030
00:50:39,633 --> 00:50:42,366
Since the days of
the Voyager launch,

1031
00:50:42,366 --> 00:50:44,566
about 50 years ago,

1032
00:50:44,566 --> 00:50:47,133
much has changed
about our fundamental

1033
00:50:47,133 --> 00:50:48,733
understanding
of the universe.

1034
00:50:48,733 --> 00:50:52,533
But what will happen in
the next 50 years?

1035
00:50:52,533 --> 00:50:54,133
♪ ♪

1036
00:50:54,133 --> 00:50:56,100
RIESS:
The last 50 years

1037
00:50:56,100 --> 00:50:57,700
was about posing some of these
very big questions.

1038
00:50:57,700 --> 00:50:58,833
I think the next 50 years

1039
00:50:58,833 --> 00:51:00,400
is going to be
about answering them.

1040
00:51:00,400 --> 00:51:02,133
Now we're left with

1041
00:51:02,133 --> 00:51:04,266
a very, very hard problem
to solve,

1042
00:51:04,266 --> 00:51:06,500
trying to understand what
dark matter is,

1043
00:51:06,500 --> 00:51:08,633
trying to understand
what dark energy is.

1044
00:51:08,633 --> 00:51:10,500
Those are not going to be
easy to solve.

1045
00:51:11,700 --> 00:51:13,533
It's a hugely exciting time

1046
00:51:13,533 --> 00:51:15,666
to be involved in physics,

1047
00:51:15,666 --> 00:51:18,233
astronomy, cosmology--

1048
00:51:18,233 --> 00:51:19,833
all the things that are
now coming together

1049
00:51:19,833 --> 00:51:22,466
to help us understand
our universe at large.

1050
00:51:22,466 --> 00:51:24,533
RHODES:
We're doing the experiments now

1051
00:51:24,533 --> 00:51:27,066
that might allow us
in 50 years to say,

1052
00:51:27,066 --> 00:51:29,633
"Wow, there was
another revolution

1053
00:51:29,633 --> 00:51:33,500
"in the mid-2020s or
around the time 2030...

1054
00:51:33,500 --> 00:51:37,000
that gave us a whole new way
to look at the universe."

1055
00:51:38,000 --> 00:51:40,300
DE SWART:
Dark matter is going to be
the most exciting thing

1056
00:51:40,300 --> 00:51:42,833
that's going to happen
in the next 50 years.

1057
00:51:42,833 --> 00:51:44,400
Because either
they're going to find it,

1058
00:51:44,400 --> 00:51:46,533
or it's going to
be incredibly exciting

1059
00:51:46,533 --> 00:51:48,166
because they're
going to not find it,

1060
00:51:48,166 --> 00:51:49,833
and then people are going to
tear their hairs out,

1061
00:51:49,833 --> 00:51:51,366
because what
are we going to do now?

1062
00:51:51,366 --> 00:51:54,766
♪ ♪

1063
00:51:54,766 --> 00:51:56,733
It really
is truly hard to imagine

1064
00:51:56,733 --> 00:51:59,066
what our model,
and what our thinking will be.

1065
00:51:59,066 --> 00:52:02,066
We will find new things,
it's undeniable.

1066
00:52:03,700 --> 00:52:04,800
What I would love to learn
more about,

1067
00:52:04,800 --> 00:52:07,366
if I had a time capsule
to zoom forward right now,

1068
00:52:07,366 --> 00:52:08,833
is to ask,

1069
00:52:08,833 --> 00:52:11,100
what are the questions we
didn't even think to ask today?

1070
00:52:11,100 --> 00:52:13,066
What's really
going to surprise us

1071
00:52:13,066 --> 00:52:14,500
that we didn't even wonder,
to wonder about?

1072
00:52:14,500 --> 00:52:17,000
♪ ♪

1073
00:52:39,133 --> 00:52:42,200
♪ ♪

1074
00:52:43,133 --> 00:52:50,466
♪ ♪

1075
00:52:54,300 --> 00:53:02,100
♪ ♪

1076
00:53:05,733 --> 00:53:13,266
♪ ♪

1077
00:53:15,100 --> 00:53:22,433
♪ ♪

1078
00:53:24,066 --> 00:53:31,600
♪ ♪