The theory of cosmic inflation, which...
On march 17, 2014,
a team of astronomers made an announcement
that triggered sensational headlines around the world.
They've detected gravitational waves, or ripples,
in what they believe is the oldest light in the sky.
It's being called one of the greatest discoveries in science.
By using a telescope at the south pole,
the researchers had detected a signal
indicating gravitational waves,
folds in the fabric of space and time
that were made just fractions of a second after the big bang.
This is the farthest back we will ever have seen
in the history of the universe.
This is the inside story of scientists who announced
one of the greatest discoveries of the century...
This would be one of the final confirmations
not only of inflationary theory
but also the general theory of relativity.
Only to have it called into doubt.
As happens in every scientific claim,
people begin to look more closely
and examine whether or not that claim is really justified.
It's been an emotional roller coaster for the team.
Captions by vitac... www.vitac.com
captions paid for by discovery communications
♪♪
The south pole, nearly 10,000 feet above sea level,
one of the coldest and remotest places on earth.
Here can be found earth's clearest view of space
for the telescopes operated by astronomer John Kovac.
Well, welcome to the south pole.
Behind me, in these crates are parts of our latest telescope.
We're gonna spend the next few weeks
putting it together here at the south pole.
And then it's gonna begin scanning the skies,
looking at the oldest light in the universe.
The signals that we hope that we'll be searching for, though,
are from gravitational waves
that come from a period even earlier,
in the first tiny fraction of a second
of the universe's history.
Gravitational waves were first predicted by Albert Einstein
almost exactly a century ago.
Distortions of space and time
should propagate through the universe
like waves in the ocean.
The gravitational wave is really just what it sounds like.
It's a wave of gravity.
It's a ripple in space-time.
Gravitational waves can arise whenever you have
a rapid acceleration of mass in the universe.
So a classic example is colliding black holes
spiraling around each other.
If a gravitational wave much, much larger
than any one we could ever possibly imagine
were to pass right through this room,
it would look like the room would get squashed
and then expanded.
It would pull everything apart, squeeze it all together,
pull it apart again with a certain pattern.
So it would distort the space-time in the room.
Theoretically, gravitational waves
should be produced on a regular basis by any massive disturbance
such as colliding black holes or exploding stars.
LIGO is an experiment that uses lasers in an attempt to detect
these recently produced gravity waves.
But the gravitational waves
that John Kovac and his team hope to find
have a much more ancient origin.
The gravitational waves that we're searching for
come from the very first moments after the big bang.
The first tiny, tiny fraction of a second after the beginning.
Zero-point-zero-zero-zero-zero
with 34 zeros and a one seconds.
The very first instance of time.
Every year, John Kovac and the team travel here
to the Amundsen-Scott south pole station,
where their telescopes are based.
It is one of the three
permanent U.S. research stations in Antarctica.
And to get here requires a ski-equipped LC-130 aircraft.
The air temperature
is about minus-30 centigrade in the summertime.
You step out of the aircraft,
and the cold hits you like a slap in the face.
You actually have to breathe very carefully
to avoid burning your lungs.
The south pole station can accommodate up to 150 people.
This is where the bicep team stays
when carrying out work on their telescopes.
So there's a big-sized station
with a cafeteria with all the rooms,
and a basketball court and a greenhouse.
And then about a mile from there is where our experiments are.
The team uses two telescopes to search for gravitational waves,
the Keck array and bicep.
The south pole is a great place
for us to put our microwave telescopes
because here at south pole, the air is the coldest on earth.
It's incredibly dry.
There's very little that gets in the way
of our microwave telescopes' observations.
It's almost like the telescopes being in space.
That's really important because the telescopes are searching
for exceedingly faint signals, signals that might arise from
gravitational waves in the early universe.
Doing astronomy at the bottom of the earth
brings its own unique challenges.
The team works on their telescopes
during the few months of the antarctic summer.
But it is in the antarctic winter
when most of the observations are done.
South pole station is only accessible
for about three months out of each year.
The temperatures are only warm enough to fly planes in and out
for that period of time.
So when we take one of these telescopes,
like Bicep1 or Bicep2, to the south pole,
we come in with a team,
and we work furiously for three months
to try to get everything to work,
to put it all together, to calibrate it, to tune it up,
to get it in pristine condition.
And then, all of us get on an airplane and leave,
except for one guy.
He watches the plane go
and knows there isn't going to be another one
for about nine months.
Engineer Steffen Richter was the one guy left
to operate the Bicep2 telescope over three antarctic winters,
when the sun doesn't rise for six months.
Back in those days, we had to top off the telescope
with liquid helium every three days.
And that had to happen no matter what the weather was.
The temperature can range anywhere
from minus-40 to minus-73 centigrade,
which is close to minus 100 in Fahrenheit.
There's a daily walk out to the telescope,
just to go to work...
There's no traffic.
There's beautiful stars out there,
and there's Aurora almost every day in the winter.
I personally think
it's one of the most beautiful commutes in the world.
It's akin to being in space.
You get an amazingly unique experience
when you spend a winter at south pole.
When the team first started hunting for gravitational waves,
the prospect for success seemed remote.
It's kind of a brave thing to devote years of your life
to going after the signal that may or may not be there.
A colleague of mine called this a wild goose chase.
A wild goose chase.
It was described in those terms
by Andrew Lange, my mentor at Caltech.
He like to say, you know,
it's better to fail at something important
than to succeed at something unimportant.
So I think it's with this mind set
that we collectively started doing that back in 2003.
When John Kovac and his team
embarked on their epic challenge,
there was not a single observation
from any telescope in the world
indicating that gravitational waves actually exist.
What there was was one man and his theory,
the theory that started this entire wild goose chase.
Okay. We can get started now.
Good morning, everybody.
This is the man who inspires his colleagues
to spend their lives on a scientific goose chase.
Professor Alan Guth.
He's one of the world's most eminent cosmologists.
Back in the 1970s when Alan was at the beginning of his career,
he grew frustrated with what was known as the big bang model.
This is the idea that the entire observable universe
emerged from a tiny, hot, dense region of space
and has been expanding and cooling ever since.
The conventional big bang theory
described how the universe expanded, how it cooled,
how the matter coagulated to form galaxies and structures.
Oddly, though, in spite of its name,
it really said nothing about the bang itself.
I like to say that it didn't tell us what banged,
why it banged, or what happened before it banged.
In December 1979,
Alan came up with a revolutionary new idea
for what happened in the first fractions of a second
after the big bang.
He named his theory the theory of inflation,
and it was to have a profound effect on cosmology.
These, actually, are copies of the notebook pages
that I wrote in the night
that I came up with the idea that has become inflation.
I went home one night
to my rented house in Menlo park, California,
and wrote down the basic equations.
And I became very excited about it,
and I even made a comment here with a double box around it,
which is not the sort of thing I do very often.
"Spectacular realization" doubly boxed.
I had only been working on cosmology
for about a year or so at this time.
So I was very worried
that when I started showing it to other people,
somebody would point out
something that was obviously wrong about it.
But I was excited nonetheless, and the next day,
I started telling my friends about it.
The equations that Alan had written down that night in 1979
were just the beginning.
Within a few months,
Alan went on a tour of universities around America,
giving a series of talks
to promote his bold, new idea of inflation.
I first heard about inflationary theory in spring of 1980
when Alan Guth came by to give a talk at Harvard university
introducing this new idea of the inflationary universe.
Alan embarked on a tour of American universities,
ripping up conventional ideas about how the universe began
and pushing further back in time
than anyone had dared to do before.
The title of the talk that I was using at that time
was "10 to the minus 35 seconds after the big bang".
This was one of the most exciting talks
I have ever heard.
Alan was trying to correct a number of flaws
in the original hot big bang model.
Alan's theory neatly explained
the first few moments of the universe
by adding a new twist called inflation.
Inflation caused the universe the expand astonishingly fast
before suddenly slowing down.
Inflation is basically a theory of the bang of the big bang.
It's a theory that describes what propelled the universe
into this period of gigantic expansion
that we call the big bang.
A plausible number, for example,
for the starting time of inflation
might be something like 10 to the minus 37 seconds
after the instant of creation.
So something like
a trillionth-trillionth- - trillionth of a second
after the big bang.
An incredibly short length of time.
It took me a long time to convince myself
that made any sense to talk about these things.
Once it starts,
the universe would double in size over and over again
every trillionth-trillionth- trillionth of a second.
A typical size for the universe at the beginning...
Something like 10 to the minus 24 centimeters across.
Decimal point, 23 zeroes, 1 centimeters.
Unbelievably small.
This is more than a billion times smaller
than the size of a single proton.
By the end of the inflationary period,
the final size of the universe
will be something on the order of maybe 1 centimeter.
It's still small at that point,
but this is still the early universe.
From then on, it goes from the 1-centimeter stage
to the universe we observe today.
With his new inflation theory,
Alan had fundamentally rewritten how the universe was born.
The theory of inflation is a little bit crazy,
but it really does a very natural, nice job at explaining
some of the most puzzling features of our universe.
Alan showed in his lecture how inflation,
this incredible burst of expansion after the big bang,
could very neatly explain
some of the great unsolved mysteries of the universe.
Why is the universe so large
with a geometry that appears to be almost perfectly flat?
And why, at the largest scale,
is the universe so incredibly uniform in all directions?
It was a triumph of science.
But the idea of inflation has not been universally accepted.
One thing above all would put the theory beyond question...
The discovery of its greatest prediction,
gravitational waves from the beginning of time.
Alan Guth believes the discovery of the universe started with a bang... on,
a massive, instantaneous explosion
big enough to leave waves of space and time
that still ripple today.
He predicted the existence of gravitational waves,
but no one has actually observed them.
Before we just accept this is what happened,
it's really, really, really critical
that we see the experimental evidence.
That's why we have to go out with our experiments
and actually measure something that tells us
whether inflation is correct or is just the wrong theory.
A detection of gravitational waves is often described
as the smoking gun signature of inflation.
It proves that inflation really is responsible
for kicking off the start of our universe.
If gravitational waves are detected,
that provides very strong evidence
to this whole story of inflation.
The theory of inflation actually predicts
that there will be gravitational waves.
But it doesn't tell you how much, how big they'll be.
It just says that, you know, they'll exist.
The gravitational waves
which we can potentially observe right now,
they were produced
approximately one trillionth of a trillionth
of a trillionth of a second after the big bang.
So when people talk about
gravitational waves from the big bang,
you might be tempted to think that it...
This is some huge shock wave
propagating through the universe.
This isn't true at all.
The secret to gravitational waves from inflation
is really quantum mechanics.
It's simply the fact that on very small wavelengths,
quantum theory tells us that everything fluctuates,
including the gravitational field.
Quantum mechanics says
you can't pin down a physical system to something
that is an absolutely, precisely defined state.
There will always be some uncertainty.
There will always be some quantum mechanical jiggle
in the universe.
So what that means is
the gravitational field during inflation
is not precisely smooth.
It has these little jiggles.
What inflation does
is it stretches out these very small fluctuations
to make the wavelengths large enough
that they can be observed in the early universe.
And if inflation
really did produce these gravitational waves,
they might still be detectable with telescopes.
So the way we are searching for this gravitational wave signal
is to study the microwave background.
It's the oldest light in the universe,
and it's a treasure trove of information.
But it really gives us a snapshot of the universe
as it looked 300,000 years or so after the big bang.
The cosmic microwave background is essentially
the afterglow of the big bang,
released as the universe cooled down.
This light, now incredibly faint,
still fills the entire universe.
Gravitational waves would have affected
the orientation of these lightwaves,
what's called polarization.
So the cosmic microwave background has a polarization.
And polarization is kind of like a directional thing.
So think of a passing
of little headless arrows over the sky.
Gravitational waves stretching and compressing
would leave an effect
on the polarization of the cosmic microwave background.
It would produce a particular swirling pattern
in that polarization that we call a b-mode polarization.
It's kind of a pinwheel pattern of polarization
or a twisty pattern.
A curly pattern on the sky.
It's the unique signature of gravitational waves.
Gravitational waves stretching and compressing space,
would've left this pattern imprinted
in the cosmic microwave background,
the afterglow of the big bang.
If that b-mode signature is there,
it is an incredibly powerful messenger
coming to us from the first tiny fractions of a second
of the universe's history.
The hunt for gravitational waves from inflation
had become a hunt for this b-mode.
If inflation theory was correct,
then this b-mode was out there, waiting to be found.
So behind me, you see one of our telescopes.
It's actually a very simple design.
It consists of a number of small two-lens refracting telescopes,
each of which has an entrance aperture
of only about this big, 30 centimeters.
It's scanning back and forth on a relatively small patch of sky,
relentlessly collecting microwave photons.
And it needs to do that because
the b-mode polarization signals that it's looking for
are exceedingly faint.
The team's first telescope, Bicep1,
saw first light in the antarctic summer, January of 2006.
But after three years of steady observation,
there was little to show for it.
No glimpse yet of any b-modes.
The wild goose chase may have been just that.
P scientists' first no glimpse at tempt b-modes.
At finding gravitational waves was a failure,
but not a dead end.
The next step... Build a bigger telescope.
In November 2009,
John and the team were back at the south pole
to install a new telescope, Bicep2.
Even before the 3-year observation of Bicep1 ends,
we already knew we want something more sensitive.
In Bicep1, we had nearly 50 detector pairs.
In Bicep2, we had about 250,
and each one is slightly more sensitive than Bicep1.
So in the end,
we get almost a factor of 10 improvement in sensitivity.
So this is the detector technology in Bicep2.
And what you see here is effectively a printed camera.
Each of these pixels is basically a camera
in the sense that it's not just the detector.
It's actually the lens and the filter, as well.
Like its predecessor, the Bicep2 telescope
was in operation across three antarctic winters,
continuing the hunt for gravitational waves.
It was a quantum leap in sensitivity.
We were able to map the sky 10 times faster with Bicep2
than we could with Bicep1 and achieve much more sensitive maps
of the polarization in the same patch of sky
that we had observed before, but much deeper now.
We analyzed the data as it came in
through 2010 and through 2011,
the first two seasons of operation.
But we quickly ran into a problem.
We did all these tests with Bicep2,
and you couldn't get rid of this signal.
The Bicep2 telescope had picked up a signal, and it displayed
all the characteristics of gravitational waves.
It had the distinctive swirling pattern,
the b-mode that John and the team had been looking for.
Yet it was less faint than they'd been expecting.
Something did not seem quite right.
It was at a much higher level than we were expecting,
either from emission from our own galaxy
or really from what we thought were favored models
of inflationary gravitational waves.
It was higher than either of those,
and so we thought, "uh, well, the signal can't be real.
It must be a problem with our instrument.
There must be some kind of subtle effect
that we haven't yet controlled in the experiment
that's producing a false b-mode signal."
Yet tests confirmed
that there was nothing wrong with the telescope.
The signal that had been detected was real.
It was coming from the sky.
Once you've established that there's a signal,
then the next question is, "what is the signal?"
You can't just assume right off the bat that you're looking at
the signature of primordial gravitational waves.
It would be nice if you could, but unfortunately,
although most of space is remarkably empty,
and therefore we can make a lot of measurements
of the microwave background,
we live in a galaxy.
And within our own galaxy,
there are a number of sources that can create a polarization
that have b-mode patterns.
So the two ones that we worry about the most
are something called synchrotron radiation
and something called dust emission.
Synchrotron radiation is a type of light
that is produced in the galaxy
when its magnetic field
sends tiny electrically charged particles
whizzing around very fast in spirals.
This can mimic the b-mode pattern of gravitational waves.
But using data from a satellite,
the bicep team was able to show that this effect was too small
to produce the signal that they had detected.
Synchrotron radiation was ruled out.
The other big potential contaminant is dust,
and this dust isn't so different
from the dust in your living room that you see
when the sun pours through the windows.
It's made up of carbon and silicates,
just, like, little rock...
Bits of rock coated in... In water ice.
And these little dust grains
can line up in the magnetic fields.
And then when light shines through them,
they can create a little bit of polarization.
Dust was harder for the team to discount.
There was less data available.
But the models that did exist suggested
that dust wouldn't produce such a large signal.
Dust was also ruled out.
Once you're really convinced
that you're seeing a signal that comes from the early universe,
then you can say you've detected primordial gravitational waves.
And the team now felt that this was the most likely conclusion.
After 4 years of analysis,
everything pointed to the signal coming from gravitational waves.
So as the final tests of the Bicep2 data set
were completed by our analysis team,
we called a collaboration-wide meeting,
and about half of us were calling in from the south pole,
and half of us from locations around north America.
We had looked at the data set
in every way that we knew how to,
scrutinized it from every different angle
and convinced ourselves
that there were no other tests that we could perform.
We were feeling at that stage that it was our obligation
to share our results with the community,
in fact, that it was overdue that we do so
because we had had that data for so long at that point.
The team members had kept their discovery under wraps.
But now, finally, they felt compelled
to go public with their news.
We knew that it was time
to show the b-mode map that Bicep2 had made to the world
and not keep it a secret any longer.
But first,
there was a very special person they needed to tell.
In December 2013,
John Kovac returned from the south pole.
As the team prepared to announce
their discovery of gravitational waves,
there was one man above all
with whom John wanted to share the news...
The man whose theory
had predicted the existence of these space-time ripples
from the early universe.
John initially sent me an e-mail
saying that he would like to talk to me urgently
about "an issue that's very important
to your research and mine."
A meeting was hastily arranged at MIT in Boston.
I got in a taxicab and drove over here
on the evening of Monday, march 10th of this year, 2014.
I walked down the corridor behind me and carried the draft
of the paper that we had been preparing.
We arranged for him to come
through the back door of the center for theoretical physics
so he would be unlikely to be noticed
by the other people in the center.
I was greeted by Alan very cordially, very calmly.
In fact, we both sat down,
and he knew immediately what this would be about.
This was the news
that Alan had been waiting for more than 30 years to hear,
definitive proof that his inflation theory was right.
Well, he told me that his group had been looking for years
to examine the possibility of gravitational radiation
from the early universe.
He told me that he was initially skeptical
that it could be found.
He told me that once they had a signal,
he was very anxious to make sure
that the signal passed all possible tests
to be sure that it was real and that, gradually,
he and the rest of the group became convinced
that the signal was real and that, now,
they were ready to make a public announcement about that.
John's team had potentially made a Nobel prize-winning discovery.
I think we were both very excited.
My reaction at the time was amazement.
I was astounded to suddenly have a group come forward
and say that they had a measurement
with unbelievably high statistical significance.
It really was a shock to me and, of course,
a very pleasant shock because it would be very strong evidence
for inflation if it was real.
It happened in less than a trillionth of a second
after the big bang.
They detected gravitational waves or ripples
in what they believe is the oldest light in the sky.
On march 17, 2014, the team announced their discovery
at a Harvard press conference.
So when we announced Bicep2's b-mode findings,
we knew that that would generate some news.
But we were not expecting anything like the attention
that the release got or the excitement that it produced.
Honestly, I expected the reaction to be fairly quiet.
The four years specifically working with this data...
The title of "detection of b-mode polarization
in the cosmic microwave background",
with that title,
you wouldn't think it will generate much interest.
But it did.
So times change very rapidly.
And then we surround the telescope...
It was emitted 380,000...
I first got wind of the Bicep2 signal about a week beforehand.
The Bicep2 announcement was incredibly exciting.
This would be one of the final confirmations
not only of inflationary theory
but also the general theory of relativity.
Appearances aren't always what they seem.
So after the initial announcement and the news,
I think most people in the community
in the broader cosmology and physics community
accepted it as face value.
But as happens in every kind of claim discovery
or scientific claim,
then people begin to look more closely
and examine whether or not that claim is really justified.
So since the march announcement
of the Bicep2 detection of gravitational waves,
there's been a flurry of activity
trying to determine whether or not
the source of the detected b-modes
is actually the gravitational waves
from the early universe
or if it could be something more mundane,
like, in particular,
people are wondering if it could be dust in our own galaxy.
The possibility that dust in the milky way
might produce a b-mode signal
had been considered by John and the bicep team.
They had chosen a patch of sky known as the Southern hole
precisely because it was relatively clear
of galactic dust.
Yet the team's work came under increasing scrutiny.
When we announced this result,
the most important fact for us was that it was real.
It wasn't produced by the instrument.
And that was the hard part as far as we were concerned.
That was what we had spent the last 14 years doing.
At that time, based on the information that was available,
whose uncertainties were rather hard to quantify,
it looked very much like a large fraction, you know,
90% of the signal was gravitational waves.
The uncertainty over the real identity of the Bicep2 signal
was to grow as, in Europe, a separate team of scientists
began to release new data about galactic dust.
The world's best data on polarized dust is available
from the Planck satellite.
So what they knew about dust emission
in our particular field in march,
you would have to ask them.
Yes.
But we had already sufficient information to be quite sure
that the optimistic modeling of bicep was not proper.
The Planck satellite was a state-of-the-art telescope
that, for several years, had been surveying the skies
from its vantage point in space.
Its principal mission had been
to make the most detailed map ever
of the cosmic microwave background,
the afterglow of the big bang.
To accomplish that task,
Planck had also carried out the best measurements ever made
of galactic dust.
The new data from Planck revised the older models of dust,
the models the bicep team had relied on.
Galactic dust is brighter than anyone had expected.
Planck's new measurements bring the entire discovery
of gravitational waves into question.
The discovery of gravitational Planck's new measurements waves arrived with much fanfare.
But within months, this great scientific breakthrough
was being second-guessed.
The Planck space telescope had gathered new data
that the bicep astronomers desperately needed.
There was a great confluence of interest from the Planck team
and from our own team,
a realization that there was a critical,
exciting scientific question at stake here.
And the best way to answer it
was to use all of the best data in the world
all together in one analysis.
So, in a sense, we set up a memorandum of understanding
between the two teams, and went on with it.
In July 2014, the two teams began sharing their data,
using the measurements of galactic dust emission
from the Planck satellite to find out
where in the universe the Bicep2 signal might have come from.
Let's make an analogy.
I'm listening to some headphones.
Imagine that there are two tunes that are playing,
and I'm trying to hear one tune,
which is the gravitational wave signal that we're after.
But there's also another tune that's playing
that's potentially a bit louder, right?
And that's the galactic dust emission.
And by using the data from Planck,
the higher-frequency data from Planck,
we can actually essentially make that distracting tune quieter
and improve our ability
to listen for that gravitational wave signal.
You... you... we're... We're at a fork in the road.
If this is positive, this is just amazing.
I mean, you know, it means that, well,
we have discovered primordial gravitational waves,
and we have actually discovered them jointly.
On the other hand, if it, say, if it was a false hope,
well, let's know it.
On January 30, 2015,
the two teams released the results of the joint analysis.
What bicep has done is a tour de force.
It's a magnificent measurement.
It will be tantalizing, exciting...
But we confirmed that this is not a discovery.
So the results of the joint analysis of Bicep2 with Planck
is that the... The most likely answer
is that 75% of the signal that we're seeing
is due to galactic dust.
But, and this is a very important but,
there's a big uncertainty on that 75%, right?
That uncertainty spans the range of half to 100%, right?
I have a piece of coal,
and I'm not able to tell you how much gold is in there.
Did I detect something?
Do you think you are rich?
You just don't know.
The bicep team had no choice but to withdraw their claim
to have discovered gravitational waves.
So at this point in time, the proper scientific statement
is that there's no evidence of gravitational wave, b-modes,
and that if they exist, they are...
They're less than about half of the signal that we're seeing.
It's a disappointing result for the bicep team.
That's the cruel reality of being experimentalists.
And that's the point of it.
The last 9 months has been absolutely
an emotional roller coaster for the team
and, you know, really quite difficult, in many ways.
We're not used to being in the spotlight in this way.
And so it's difficult for a scientist
to know exactly how to react.
We did underestimate
the level of dust correlation in our original announcement.
There is no denying in that.
But that's because of the lack of data,
not because we did anything wrong.
One of the greatest discoveries of the century
had eluded the bicep team.
For now, gravitational waves have escaped detection.
The path ahead is very clear.
We have telescopes that are operating right now
that are producing more and more powerful data.
Next in the series of telescopes is going to be Bicep3,
and that's going to be another jump again in sensitivity
and push further and further the knowledge that we have
about what the sky tells us
about the first fractions of a second
in the history of our universe.
And the bicep team are not alone.
Around the world, many scientists have also embarked
on the hunt for gravitational waves.
From the Atacama desert of northern Chile
to the wilderness of Antarctica,
the quest to confirm how the universe was born,
to find the wild goose of inflation, continues.
It's a process that we all, as scientists,
are absolutely committed to getting to the truth
wherever it leads us.
As far as I'm concerned,
inflation is still in very strong shape.
But whether or not gravitational waves
will be added to our list of pieces of evidence
for inflation...
I don't really know at this point.
For inflation...