[MUSIC PLAYING]
NARRATOR: An image
of a black hole
will provide a new way to
test Einstein's most extreme
theoretical predictions.
 Einstein's equations
show us that if you
spend an hour or two at
the edge of a black hole
and then come back to
Earth, for instance,
Earth might have aged 10,000 or
a million or a billion years.
So when we are observing the
event horizon of a black hole,
we are observing what
really can be characterized
as a time machine.
NARRATOR: Yet despite
Einstein's equations,
even he didn't think that
black holes could exist.
He didn't believe there was
a way they could ever form.
JANNA LEVIN: That's a sensible
objection that Einstein had.
I mean, after all, it'd be
very, very, very hard to do,
to crush all the mass
of something to a point.
Einstein naturally
and reasonably assumed
that matter just
wouldn't allow itself
to be compacted that much.
NARRATOR: But evidence of a
mechanism has been growing.
Scientists now
believe a black hole
is the corpse of a giant
star that's gone supernova.
Deep inside the debris,
the surviving core
collapses to an
infinitely small point.
This is called the singularity.
Its intense gravity
warps space and time
so severely that nothing
can escape, forming
the black hole's event horizon.
 It's possible that
black holes are ultimately
a figment of the
mathematical equations
that Einstein gave us.
But how better to begin
to push this understanding
than to look and see
what's actually out there?
And that's the promise of
the Event Horizon Telescope.
NARRATOR: A picture will
test one of the most
treasured theories in
science, Einstein's
theory of general relativity.
His theory says that mass curves
the fabric of space and time,
creating an effect
that we call gravity.
SCOTT HUGHES: Einstein's
theory of relativistic gravity,
that is what lays
the foundations that
set all of our understanding.
Step one is just, did
Einstein get it right?
Is there some detail
that's been overlooked?
NARRATOR: For 100
years, Einstein's theory
has passed every test,
but nobody has ever seen
its most extreme prediction.
BRIAN GREENE: How
wonderful would it
be if the event
horizon telescope
shows us that in
extreme realms, Einstein
is not completely right?
It will be one of the
most thrilling discoveries
of our age, as we will then
leapfrog forward in our grasp
of how the universe works.
NARRATOR: A challenge to
Einstein's theory and a new era
of astronomy rests on
the success of the Event
Horizon Telescope team.
