Nova (1974–…): Season 42, Episode 21 - Inside Einstein's Mind - full transcript
On November 15th, 1915, Einstein published his greatest work: general relativity. The theory transformed our understanding of nature's laws and the entire history of the cosmos, reaching back to the origin of time itself. Now, in celebration of the 100th anniversary of Einstein's achievement, NOVA tells the inside story of Einstein's masterpiece. The story begins with the intuitive thought experiments that set Einstein off on his quest and traces the revolution in cosmology that is still playing out in today's labs and observatories. Discover the simple but powerful ideas at the heart of relativity, illuminating the theory-and Einstein's brilliance-as never before. From the first spark of an idea to the discovery of the expanding universe, the Big Bang, black holes, and dark energy, NOVA uncovers the inspired insights and brilliant breakthroughs of "the perfect theory."
that shapes our universe
It feels familiar,
but it's far stranger
than anyone ever imagined
And yet, one man's
brilliant mind tamed it
Gravity
Using simple
thought experiments,
Albert Einstein made
an astonishing discovery:
time and space
are shaped by matter
You get rid of this force
of gravity,
and instead, we have
curvature of spacetime
Right now, the space around me
is being squeezed and stretched
He called it the "General Theory
of Relativity"
How did one person,
working almost entirely alone,
change everything we thought
we knew about the universe?
Einstein is toiling
as the world seems to fall apart
He was able with pure thought
to solve the riddle
of the universe
"Inside Einstein's Mind,"
right now on NOVA.
Gravity
The most familiar yet most
mysterious of nature's forces
100 years ago, Albert Einstein
made a mind-blowing discovery:
what we feel as gravity
is in fact the push and pull
of space and time itself
He called his idea
"general relativity"
It is perhaps
the most remarkable feat
of thinking about nature
to come from a single mind
General relativity
is undoubtedly one of the
greatest scientific theories
ever conceived
It's a theory of space, time,
and gravity
One mathematical sentence,
and from it, you can derive
the understanding
of the entire universe
on the largest scales,
and that is beautiful
Only now, a century
after it was first proposed,
do we have the technology
to explore the extremes
of Einstein's great theory
Supermassive black holes
at the center of galaxies
Waves of gravity that
distort space and time
The evolution
of our entire universe
How did a concept
that explains so much
come from the mind of one man?
Einstein had a magical talent
He could take a hard,
physical problem
and boil it down
to a powerful visual image,
a thought experiment
Suddenly he realizes,
"This is how the world works
All this abstract nonsense is
the correct theory of reality"
To gain an insight
into Einstein's mind
and the true wonder
of general relativity,
we need to trace
the crucial thought experiments
that led to his great
breakthrough
The seeds for his ideas
were planted
when he was just a child
Einstein grew up
in a small house in Munich,
in southern Germany
His unique personality
was evident early on
Like many great innovators,
Einstein was a rebel, a loner,
but deeply curious
He was slow in learning to speak
as a child,
so slow that his parents
consulted a doctor,
but he later said that
that's maybe why he thought
in visual thought experiments
His sister remembers him
building little card towers
using playing cards
He was a daydreamer,
but he was deeply persistent
Einstein's father, Hermann,
manufactured electrical
equipment
He nurtured his son's interest
in science
On one occasion,
he brought him a compass
Now, you and I maybe remember
getting a compass
when we were kids,
and we were like,
"Oh look, the needle twitches
and points north,"
but then we're on
to something else,
like, "Oh look,
there's a dead squirrel"
But for Einstein,
after getting that compass,
he developed a lifelong devotion
to understanding how things
can be forced to move
even though nothing's
touching them
The young Einstein
became gripped by a desire
to understand the underlying
laws of nature
He developed a unique way
of thinking
about the physical world
inspired by his favorite book
The book Einstein loved
told little stories,
like what it'd be like
to travel through space
or go through an electrical wire
And it made Einstein think
visually
These imagined situations
that we often call
"thought experiments"
became a defining feature
of Einstein's thinking
One of the critical
thought experiments
that Einstein began to play with
very young,
around the age of 16,
was trying to imagine
what would happen
if he could catch up
with a light wave
It's one thing to imagine
a light wave zooming past him
at some seemingly
impossible speed,
but what if he could somehow
just propel himself
really quickly?
What would it look like
if he could catch up
with that light wave?
What would he see?
He said it caused him
to walk around in such anxiety,
his palms would sweat
Now, you and I may remember
what was causing our palms
to sweat at age 16,
and it was not a light beam
But that's why he's Einstein
This dream-like thought
about the nature of light
was Einstein's first step
on the path to his great theory
It stayed with him throughout
his time at school and college
He was extremely gifted
in science and math
as a young person
and very bad at other classes,
mostly because
he kept cutting class
and being very rude
to his teachers
Many teachers
from his high school days on
were convinced he'd never amount
to anything
He was a discipline problem,
and he was bad news
He applies to the second best
university in Zurich,
the Zurich Polytech,
and gets rejected
I'd love to meet
the admissions director
who rejected Albert Einstein
But eventually he gets in,
and he does moderately well,
but not good enough
to get a teaching fellowship
And so he ends up
at the Bern Swiss patent office
as a third class examiner
Undaunted by his
university results,
Einstein started work
at the patent office in 1902,
age 23
Here, his job was to assess
the originality of new devices
He was immersed
in the kinds
of technical details
that he'd been fascinated by
as a very young kid
And here he was,
sitting in the kind of wave
of the modern age
This was the era
of electrification
So all the latest clever ideas
for switching technology,
for coordinating clocks
in particular,
those were all
passing through his office
Time zones had recently been
introduced in central Europe,
and accurately
synchronizing clocks
was a major challenge of the day
Switzerland was a world leader
in time technology
Dozens of patents to link clocks
passed through Einstein's office
He could whip through
these patent applications,
and then out of his drawer,
he'd pull his physics notes,
and his boss was very indulgent
and would sort of turn
a blind eye
as Einstein was doing
his theories in his spare time
It's really important
to remember that
theoretical physics was new
when Einstein was a young man
You could do quite a lot
of this work by reading
a relatively small number
of science journals
and making the calculations
yourself
Einstein's world in 1905
was dominated
by two kinds of physics
One was about 200 years old,
founded by Isaac Newton,
a British natural philosopher
For Newton, all there is
in the world is matter moving
Newton showed that the motion
of falling apples
and orbiting planets
are governed by the same force:
gravity
His equations are so effective,
we still use them today
to send probes to the farthest
reaches of the solar system
The other important theory
of Einstein's day
covered electricity
and magnetism
That branch of physics
had been revolutionized in 1865
by the Scottish physicist
James Clerk Maxwell
Maxwell's theory describes light
as an electromagnetic wave
that travels at a fixed speed
In Newton's world,
the speed of light is not fixed
Einstein could see that
there's a contradiction
between Newton and Maxwell
They just don't fit together
And one of the things
Einstein hated... hated...
Was contradiction
If there's one kind of physics
that says this
and another kind of physics
that says that
and they're different,
that's a sign that something's
gone wrong and it needs fixing
For months, Einstein wrestles
with the problem
Eventually,
to resolve this contradiction,
he focuses on a key element
of speed: time
He realized that
any statement about time
is simply a question
about what is simultaneous
For example, if you say
the train arrives at 7:00,
that simply means that
it gets to the platform
simultaneous with the clock
going to 7:00
In a brilliant
thought experiment,
he questions what "simultaneous"
actually means
and sees that the flow of time
is different for an observer
that is moving
versus one that is
standing still
He imagines a man
standing on a railway platform
Two bolts of lightning strike
on either side of him
The man is standing
exactly halfway between them
and the light from each strike
reaches his eyes
at exactly same moment
For him, the two strikes
are simultaneous
Then Einstein imagines a woman
on a fast-moving train,
Traveling at close to the speed
of light,
what would she see?
As the light travels out
from the strikes,
the train is moving towards one
and away from the other
Light from the front strike
reaches her eyes first
For the woman on the train,
time elapses
between the two strikes
For the man on the platform,
there is no time
between the strikes
This simple thought
has mind-blowing significance
Simultaneity,
and the flow of time itself,
depends on how you're moving
If there's no such thing
as simultaneity,
then there's no such thing
as absolute time everywhere
throughout the universe,
and Isaac Newton was wrong
This concept that time,
and space as well, are relative
became known as
special relativity
It led to remarkable results,
such as the famous equation
relating energy to mass
Einstein published
this article in 1905
to exactly no acclaim
Most people ignored it
This was not setting the world
on fire
Two years go by
before a very eminent physicist,
Johannes Stark, invites Einstein
to write a review article
on Einstein's own work,
precisely because no one
was paying attention
And he begins thinking
about ways to generalize
and to push his own results
from 1905
What if he considers
not only a train
moving at a fixed speed
past the platform?
What if that train begins
to speed up or slow down?
What if there's acceleration?
Adding acceleration to the
equations was his first task
Then there was that mysterious
Newtonian force of gravity
to contend with
In Newton's theory,
gravity is a force
that acts instantaneously
But special relativity says
that's impossible...
Nothing can travel
faster than light
What Newton's theory
tells you is that
suppose the sun
were to disappear,
the orbit of the earth should
change at that very moment
But the notion of
"at that very moment"
in two different places
is exactly one of these notions
that special relativity
has told you
isn't a good physics notion
So you've now got this challenge
of trying to work out
how to take the success
of Newton's theory of gravity
but fit it into this new
special relativistic picture
It was only when Einstein
began to understand the link
between gravity and acceleration
that things began
to fall into place
We all know that
when we are accelerated,
and of course now we have cars
and airplanes
to give us the physical feeling,
if you're in an airplane
and it's taking off,
you are pushed back
in your chair,
you feel actually kind of
a force pushing you back,
which feels very similar
to the force of gravity
But you need the brilliance
of Einstein
to explain why they are related
Suddenly, he hits
upon what he describes as
the happiest thought of his life
If gravity and acceleration
feel the same,
perhaps they are the same
Again, he examines the idea
in a beautiful
thought experiment
He imagines a man in a box
floating weightlessly
in a distant region of space
in zero gravity
Suddenly, the man stops floating
and accelerates downward
until he's standing in the box
What has happened?
Either the box
is now close to a planet
and the force of gravity
has pulled the man to the floor,
or someone has attached a rope
and the box is now
being pulled continuously
and accelerated upwards
So which is it?
Gravity?
Or acceleration?
Without being able
to see outside,
the man can't tell what's
causing his fall to the floor
Einstein realized
there is no way
to tell the difference
between sitting
in a gravitational field
and being accelerated
These are equivalent situations
The fact that these two effects
are the same,
give the same result,
means that gravity
is acceleration
It's not just like acceleration;
it's the same thing
It's a big breakthrough
Einstein's theory
of special relativity worked
for motion at a constant speed
By extending his ideas
to acceleration,
he could begin to formulate
a new theory of gravity
In 1912, Einstein is living
in Zurich with his wife Mileva
and two young sons,
Hans and Eduard
The academic world had realized
the importance
of special relativity,
and his career had taken off
He's now a professor
at the esteemed Swiss Federal
Institute of Technology,
but spends as much time as
possible working on his theory
He needs mathematics
that describes how objects move
in space and time
and soon realizes that
the best tool for the job
is a strange but powerful
concept called "spacetime"
If I think of space,
I know that I can find anything
if I know where it is
north-south, east-west,
and up-down, three points
But that doesn't mean
I can find it,
because I also have to know
where it is in time
And so if we start to think,
to know everything
about an event in the universe,
I have to know not just
its spatial coordinates,
but also its time coordinate
I can begin to think
about where it is in spacetime
Imagine a camera
filming an action,
capturing each moment in time
as a single frame
Einstein basically tells us,
"Think of the movie reel"
So you have
all these little pictures
Now, cut them apart one by one
and stack them on top
of each other,
you get this pile
And if you go up in the pile,
you go up in time
And now kind of glue them
all together into one big block,
and that block
has both space and time,
and that's the spacetime
continuum
It's almost looking at a movie
not frame by frame,
but seeing the whole movie
at once
They would now be
kind of two strands
going up in space and time,
and they would be
kind of spaghetti strands
In fact, we all are
spaghetti strands
moving in this spacetime
Einstein feels that spacetime
is the natural arena
in which his theory
of relativity should play out
But now he needs
sophisticated mathematics
By your standard or mine,
Einstein was good at math
He was Einstein
But he was not really
a mathematician per se
He didn't prove theorems,
he didn't pore over math books
He was a physicist
He did thought experiments
He thought of very tangible,
concrete situations
and what would happen
So when it came time for him
to really bear down
to the absolute cutting edge
mathematics of his day,
he required help
At university, Einstein had
skipped the geometry classes,
letting his friend Marcel
Grossman take notes for him
Grossman had excelled
in geometry
and was now chairman
of the math department
He suggests Einstein
uses advanced mathematics
in which the shape of space
and time could be curved
Because spacetime
has a geometry,
he thinks to himself,
"Well, maybe it's the actual
shape of spacetime itself
that is giving rise to gravity"
After months of work, Einstein
has an extraordinary idea
"What if spacetime
is shaped by matter,
and that's what we feel
as gravity?"
In struggling to figure out
what causes gravity then,
Einstein has this great insight
It is simply that a mass
distorts the shape of spacetime
around it
So you get rid of this force
of gravity,
and instead we have
curvature of spacetime
In Einstein's universe then,
if space were empty,
it would be flat
There'd be nothing going on
But as soon as you
put objects down,
they warp the space and time
around them,
and that causes a deviation
of the geometry
so that now things start moving
Everything wants to move
as simple as possible
through space and time
But Einstein tells us that mass
sculpts space and time,
and it's the curved motion
through this sculpture
that's the force of gravity
We have this feeling that
the reason I can feel pressure
on the soles of my feet,
that the reason things are going
to drop when I throw them,
are because there's a force
attracting us down
to the center of the earth
What general relativity tells
you is that's not the right way
to think about
what's going on there
What's really going on is that
your natural path in spacetime
would take you to the center
of the earth,
and what's actually happening is
the floor is getting in the way,
it's pushing you upwards
When we look at it, we go,
"Ah, the force of gravity"
But Einstein says, "No, no, no,
the curvature of spacetime"
It's a stunning insight
Just as an ant might feel forces
pulling it left and right
as it walks over crumpled paper
when it's simply the shape
of a surface dictating its path,
Einstein saw that what we feel
as the force of gravity
is in fact the shape of the
spacetime we're moving through
Einstein now has
everything he needs
to formulate his final theory
of gravity
But he makes a critical mistake
He misinterprets
one of his equations,
and unaware of his error,
continues working
on incorrect ideas
The point at which Einstein
is going to give
the most essential equations
of the theory,
Einstein considers
something like them
and then says,
"Ah, but these don't work,"
and then writes down
the wrong equations
What follows are alternations
of confidence and despair
as he convinces himself
that everything was fine
with this theory,
and then he realizes
that things aren't so good
with the theory
It is a long, dark period
for Einstein
as he struggles
to reconcile himself
with a theory
that is just not working
Two years later,
Einstein is in Berlin
At just 36 years old,
he has one of the most
prestigious positions in physics
But he is still struggling
with his theory
By 1915, he'd reached
the pinnacle of the profession
He's in the Prussian Academy
and a professor
at the University of Berlin
But his marriage
is falling apart,
his wife and his two kids
have moved back to Switzerland,
so he's pacing around
almost all alone
in this apartment in Berlin
And now he has a competitor
Einstein had enthusiastically
shared his ideas
with the brilliant mathematician
David Hilbert
Hilbert was so impressed,
he decided to work
on the theory himself
Einstein is now
in a race to the finish
with one of the world's
best mathematicians
This is unfolding
in a remarkably dramatic period
in history
World War I has begun
to ravage central Europe
Einstein is not just toiling
in the abstract;
he's toiling as the world
seems to fall apart
By November 1915, Einstein
is scheduled to present his work
in a series
of four weekly lectures
at the esteemed Prussian Academy
But he's struggling
to formulate his ideas
In the midst
of these challenges,
letters arrive
from his wife in Zurich
pressing the issue
of his financial obligations
to his family
and discussing contact
with his sons
As his lectures begin,
his theory is still
far from complete
The pressure on Einstein is huge
He would give a lecture,
revise it, give it again
Spot mistakes, correct them,
get up on the podium,
explain what was wrong
in the previous week's lecture,
correct it and then move on,
and then do that again and again
for four weeks running
His work to convince them
of the truth
of this absolutely radical
new theory of relativity
that he was proposing
is one of the most intense
periods of work
in the history of science
Somehow, he's able
to focus on his theory
with an incredible intensity,
and he makes his breakthrough
He tests his equations
on a problem
that Newton's theory of gravity
couldn't solve:
the orbit of Mercury
Mercury's path around the sun
has an anomaly
that Newton's theory
can't explain:
it deviates slightly
each time it goes round
Einstein calculates the orbit
with his new equations
The answer is correct,
exactly what astronomers
had observed
He'd found the final equations
for his general theory
of relativity
You have to think about the
hubris of being Albert Einstein
He had already thrown out
Newtonian mechanics
with special relativity,
and then he had gone off
on his little personal quest
to incorporate gravity
And at the end of the day,
he boils it down to a prediction
for a number
that had been observed:
the procession
of the orbit of Mercury
And, miraculously,
when the pages of algebra
work out to their end,
you get the right answer
And suddenly, it's not just
playing with equations anymore;
he realizes
this is how the world works
All this abstract nonsense is
the correct theory of reality
Einstein is at last able
to present a successful theory
That's a triumphant moment,
one of the great moments
in the history of physics,
and, for Einstein, a victory
very much against the odds,
and he'd won
On the 25th of November 1915,
Einstein lays out his findings
in his climactic fourth lecture
at the Prussian Academy
He presents general relativity
The theory can be written
as a single equation
It condenses
sprawling complexities
into a beautifully compact set
of symbols
So the formula is really simple:
G-mu-nu equals
G for the shape of spacetime
and T for the distribution
of mass and energy
So this very simple formula
captures all of Einstein
general relativity
It's a beautiful,
simple equation
but it's a lot of work
to unpack the symbols,
the mathematical symbols,
and see how
in this very simple formula,
the whole geometry
of the universe is hidden
It's kind of an acquired taste
to see the beauty
It's also a signature formula
for Einstein
The true mark of his genius
is that he combines two elements
that actually live
in different universes
The left hand side lives
in the world of geometry,
of mathematics
The right hand side lives
in the world of physics,
of matter and movement
And so perhaps the most powerful
ingredient of the equation
is this very simple
equal sign here,
these two lines that actually
are connecting the two worlds,
and it's quite appropriate
they're two lines
because it's two-way traffic
Matter tells space and time
to curve,
space and time tells matter
to move
When Einstein presented
his great theory,
few people understood it
He needed a way
to prove to the world
that the counterintuitive
features of his theory
were real
The general theory of relativity
made predictions of things
which looked really strange
For example,
the idea that light bends
when it passes near
a very heavy body
No one had ever looked for that
No one had ever observed it
Einstein was desperate,
desperate to get astronomers
to make that test
Einstein's theory predicts that
when light from a distant star
travels close to the sun,
the warped space around the sun
bends the light's path
In May 1919, the English
astronomer Arthur Eddington
traveled to the African island
of Principe to record images
that would show this phenomenon
What Eddington
had been able to do
was take photographs of stars
during a total eclipse
of the sun
so the moon blocked most
of the brightness of the sun
and little pinpricks of light
could be seen around the sun...
Otherwise, it would be lost
in the glare...
And Eddington and his colleagues
were able to measure
that the appearance
of those stars had been shifted
compared to where
they would have been
had that big mass of the sun
not been deflecting that light
from far away
So Eddington's able to show
that Einstein's general
relativity theory is right
and a revolution in science
has been accomplished
When the eclipse experiments
prove Einstein's theory right,
he rockets to fame
not just because he's explained
a new way of looking
at the universe,
but at the end of World War I,
you had the predictions
of a German scientist
be proven right
by some British astronomers,
and it becomes headlines
across the world
The New York Times says,
"Lights all askew
at the heavens,
men of science
more or less agog"
This is back when newspapers
knew how to write
great headlines
But Einstein kind of loves
this fact
that he is now an icon
of science
Einstein becomes
a worldwide celebrity,
the icon of genius
we still recognize today
The only person
who was more widely known
was Charlie Chaplin,
and they got on
like a house on fire
Chaplin said, "The reason
they all love me
"is because they understand
everything I do,
"and the reason they love you
"is that they don't understand
anything you do
Can you explain that?"
And Einstein said
But in 1930s Berlin,
the Nazi party is gaining power
As a Jewish scientist, Einstein
becomes increasingly caught up
in the political turmoil
Einstein's theories
became a target
They were deemed
aesthetically repugnant
to a kind of Aryan sensibility
So people attacked not just
Einstein the Jewish scientist,
but they would actually
have people
denouncing general relativity
In January, Nobel Prize
mathematician Albert Einstein
visited California
He begins to make trips
to America,
where he is welcomed
with open arms
Germany's loss, America's gain
And in 1933,
he settles in Princeton
with his second wife Elsa,
taking up a position at the
Institute for Advanced Study
Today, the Institute is headed
by Professor Robbert Dijkgraaf
He basically was still
very much by himself,
just actually
as he was in Berlin,
just concentrating
on his deep ideas
and struggling
with understanding the universe
Of course, his office was here
At the Institute,
Einstein worked to unify
his theory of gravity
with the other laws of physics
With Einstein,
you see this phenomena
you see with many great
scientists...
That they climb
this very high mountain
and instead of celebrating
their success,
they're privileged to see
a much wider landscape,
and they see all these mountains
behind it
And I think he was
very much aware
how much still there was
to be done
Till the very last days
of his life,
he was trying to push
these equations
and find a description
of nature, all of nature,
in terms of the geometry
of space and time
But general relativity was
fading from mainstream science
Physics was now focused
on the quantum theory
of atoms and tiny particles,
a theory incompatible
with Einstein's ideas,
but one that could be tested
in the lab
Most of general relativity
was then beyond the reach
of experiment
When Einstein died in 1955,
age 76,
his theory was seen as one
with little hope
of future discovery
The best theories in physics
always take us to places
where the people who invented
them didn't imagine
And a truly wonderful theory
like general relativity
predicts all sorts of things
that Einstein didn't conceive of
The theory has a life of its own
We understand general relativity
much better right now
than Albert Einstein ever did
Liftoff of space shuttle
Discovery
with the Hubble space telescope,
our window on the universe
Today, 100 years
after general relativity
was first presented
Telescopes released,
okay, thank you
new technology
is allowing us to explore
the most remarkable predictions
of the theory:
an expanding universe,
black holes,
ripples in spacetime,
and perhaps the most bizarre,
the idea that not just space,
but time itself
is distorted by heavy objects
To prove it,
a team of physicists
is carrying out
a remarkable experiment
They're using two atomic clocks
that are in near perfect sync,
accurate to a billionth
of a second
The master clock
remains at sea level
while they take the second clock
to the top of New Hampshire's
Mount Sunapee
General relativity tells us that
as you move away
from the mass of the planet,
time should speed up
After four days
at the top of the mountain,
the test clock is taken back
to the lab for comparison
There, they compare it
to the sea level master clock
We'll put that one
into Channel A
Four days ago,
they were ticking in unison
Master clock in Channel B
But what about now?
You guys ready?
This is it right here
The time interval counter
is gonna show us
the time difference
between these two clock ticks
20 nanoseconds
You can see the time
difference between them
represented here graphically
of the clock that was up
at the mountain for four days
and our master clock
Gravity, the distortion
of space and time,
becomes weaker as you move away
from the surface of the planet
So while the test clock
was up the mountain,
time sped up
It's now 20 nanoseconds,
20 billionths of a second,
ahead of the sea level clock,
This is really awesome
This distortion of time
has surprising consequences
The Global Positioning System,
something we all take
for granted,
wouldn't work without
taking this into account
The engineers who built
the GPS system
we use every day
to pinpoint locations
had to ensure it adjusted
for the time difference
between clocks on satellites
and receivers on the ground
If they didn't, GPS would be off
by six miles every day
Your GPS units
use the results
of general relativity
When you navigate in your car,
you perhaps should give a word
of thanks to Uncle Albert
Of all general relativity's
predictions
that new technology
has allowed us to explore,
there's one that's
straight out of science fiction:
a black hole
Everything that we're
familiar with in ordinary life
is made from matter
But not black holes
Black holes are made
from warped space and time
and nothing else
A black hole is an object
that is spherical,
like a star or like the Earth,
with a sharp boundary
called the horizon
through which nothing
can come out
So it casts a shadow
on whatever is behind it
It's just a black, black shadow,
unbelievably black
This simulation shows
the distortion of starlight
around a black hole
Even though Einstein knew his
theory predicted black holes,
he found it hard to believe they
would really exist in nature
In the 1960s,
Professor Kip Thorne
worked on the mathematical
concept of black holes
The idea made sense on paper,
and he began to feel that these
science fiction-like objects
might actually be real
Must be here somewhere,
it's in one of these piles
Kip Thorne made a bet with
fellow physicist Stephen Hawking
about whether or not
a strong source of x-rays
known as Cygnus X-1
was in fact a black hole
I think it's in here
Yeah, here we go, relativity,
stars and black holes
Yeah, there it is
So that is a copy
of the famous bet
"Stephen Hawking
bets a one-year subscription
"to Penthouse magazine
"against Kip Thorne's wager
of a four-year subscription
"to a political magazine called
Private Eye
"that Cygnus X-1 does not
contain a black hole of mass
"above the Chandrasekhar Limit
It's witnessed this 10th day
of December 1974"
Stephen Hawking had
a terribly deep investment
in it actually being
a black hole,
and so he made the bet against
himself as an insurance policy
that at least he would get
something out of it
if Cygnus X-1 turned out
not to be a black hole
The evidence mounted thereafter
over the period
of the '70s and '80s,
and in June 1990,
Stephen snuck into my office
and signed off on the bet,
that finally, the evidence
was absolutely overwhelming
that Cygnus X-1
really is a black hole
And Penthouse magazine arrived
He sent me the British version
of Penthouse,
which was ever
so much more raunchy
than the American Penthouse,
actually
Enough to make my face turn red
when I received it at first
Today, we have evidence
suggesting that
there are millions of black
holes in our galaxy alone
But perhaps the most profound
prediction of general relativity
is that our universe
had a hot, dense beginning
that we call the big bang
The discovery that distant
galaxies are moving away from us
and that there's a background
radiation permeating space
provided evidence
for the big bang
and a universe that's growing
With this picture
of an expanding universe,
there were natural questions
Is the universe slowing down
as it expands?
Is it so dense that someday,
it will come to a halt
and collapse?
Will the universe come
to an end?
These seemed like good questions
To find answers, in the 1990s,
Saul Perlmutter and his team
observed exploding stars,
called supernovae,
to track the growth
of the universe
When we made the measurement,
we discovered that the universe
isn't slowing down enough
to come to a halt
In fact,
it's not slowing at all;
it's speeding up!
The universe is expanding
faster and faster
But what's pushing it?
In order to explain
the acceleration of the universe
within Einstein's theory
of general relativity,
we're considering an energy
spread throughout all of space
that we've never seen before
We don't know what it is
We call it dark energy
And, if so, it would require
something like 70%
of all the stuff of the universe
to be in this form of previously
unknown dark energy
So this is a lot to swallow,
and you might imagine that
at that point,
you should go back
and revisit your theory
The problem is that Einstein's
theory is so elegant,
and it predicts many, many,
many digits of precision,
that it's very, very difficult
to come up
with any other theory
There is one final prediction
of general relativity
that remains untested:
gravitational waves
There are huge things
in the universe happening,
like black holes colliding
or stars exploding,
and they create these
gravitational waves...
Waves in the shape
of space and time
that travel through the universe
at the speed of light
And so right now,
the space around me
is being squeezed and stretched
by gravitational waves
just getting here
from, let's say, two black holes
colliding a billion
light years away
But the squeezing and stretching
is so minute,
I absolutely could not
personally detect it
And so what we're trying to do
is build an instrument that can
In Louisiana
and Washington state,
a vast experiment called LIGO
is in the final phases
of calibration
It's hoped that laser beams
traveling two-and-a-half miles
between precisely aligned
mirrors
will measure
the squeezing of space
caused by gravitational waves
This could open up an entirely
new window on the universe
For 100 years,
general relativity
has been proven to be correct
time and time again
But Einstein himself knew that
his great theory had limits
It remains incompatible
with the quantum world
of tiny atomic particles
Here at the Institute
for Advanced study,
where Einstein worked,
the world's leading
theoretical physicists
are trying to solve the problem
Einstein never could:
finding a single set of rules
that applies to both the cosmic
and atomic scales
A unified theory
The Holy Grail of physics
We are now in what at this time
is the school of physics
So here,
people are still struggling
with many of the same issues
that Einstein would struggle
and are still trying to capture
the laws of the universe
from the very small to the very
large in a single equation
And it's still blackboards
that are the weapon of choice
The brightest minds of the world
are coming here
to work 24 hours,
seven days a week,
struggling to grasp the great
mysteries of the universe
And I think we are still driven
by the same dream:
that at some point,
we can capture everything
in elegant mathematics
100 years after Einstein
transformed our understanding
of nature,
the stage is set
for the next revolution
When we finally move
beyond Einstein,
it might be another singular
genius that comes along...
Someone struggling in a poor
school in Kenya right now
that we don't know about
Or it might be
20 different people
with 20 different points of view
gradually building
brick-by-brick
to finally figure out
a more comprehensive view
that includes general
relativity in it
I think the most important thing
that you learn from Einstein
is just the power of an idea
If it's correct, you know,
it's just unstoppable
It's extremely encouraging that
he was able with pure thought
to solve the riddle
of the universe
Once we had general relativity,
the world changed completely
Our point of view on the world
changed completely
I mean, the origin
of the universe
is a prediction straight out
of general relativity
We didn't have that before
I often wonder
what Einstein would make
of today's theoretical physics
I think he would really be
saying, you know,
"Get on with it, get the right
story, get the details right"
You know, you have
the huge universe,
and it obeys
certain laws of nature,
but where in the universe are
these laws actually discovered?
Where are they studied?
And then you go
to this tiny planet
and there's this one individual,
Einstein, who captures this
And now there's
a small group of people
walking in his footsteps
and trying to push it further
And I often feel,
well, it's this small part
of the universe
that actually is reflecting
upon itself,
that tries to understand itself