Nova (1974–…): Season 35, Episode 9 - Absolute Zero: The Race for Absolute Zero - full transcript
Nova examines scientific efforts to produce colder and colder temperatures.
Text : WTC-SWE
(male narrator)
The greatest triumph
of civilization
is often seen as
our mastery of heat.
Yet our conquest of cold
is an equally epic journey
from dark beginnings
to an ultra cool frontier.
In the last 100 years,
cold has transformed
the way we live and work.
Imagine supermarkets without
refrigeration or frozen food,
skyscrapers
without air-conditioning,
hospitals without MRI machines
or liquid oxygen.
We take for granted
the technology of cold,
yet it has enabled us
to explore outer space
and the inner depths
of our brain.
And as we develop new
ultra cold technology
to create quantum computers
and high-speed networks,
it will change
the way we work and interact.
By the late 19th century,
the ultimate extreme of cold
had a number,
-273 degrees Celsius,
and a name..."Absolute Zero."
A frontier so enticing
that rival physicists
from all over Europe
began a race
towards this absolute
limit of cold.
It was a high-stakes pursuit,
one that continues
even now as we explore
a strange quantum world
where fluids
appear to defy gravity
and electricity flows freely
without resistance.
"The race for Absolute Zero,"
up next on "NOVA."
(narrator)
A century ago, Antarctic
explorers were pushing
further and further towards
the coldest place on Earth,
the South Pole,
where temperatures
can plummet to -80 degrees.
The competition to reach
this goal was matched by
a less publicized, but equally
daunting scientific endeavor,
the attempt to reach
the coldest point
in the universe--absolute zero.
Was it possible to attain this
ultimate limit of temperature,
-273 degrees Celsius?
Only in a laboratory
by liquefying gases
could scientific adventurers
take the first steps
towards this Holy Grail,
a place where atoms come
to a virtual standstill,
utterly drained
of all thermal energy.
Among the front-runners in
the race towards absolute zero
was James Dewar, a professor at
the Royal Institution in London.
(man, as James Dewar)
It will be the greatest
achievement of our age.
(narrator)
In 1891, he gave
one of his celebrated
Friday night public lectures
on the wonders of the super cold
to celebrate the centenary
of his great predecessor,
Michael Faraday.
The descent to a temperature
within 5 degrees of zero
would open up new vistas
of scientific inquiry,
which would add immensely
to our knowledge
of the properties
of matter.
James Dewar is a canny
and I think very ambitious,
practically-minded
Scottish scientist.
He could really show
both his colleagues
and the fee-paying audiences
some of the secrets of nature.
Take this rubber ball...
it bounces well,
I think you'll agree.
But let's see what happens
after a few seconds' immersion
in liquid oxygen.
(narrator)
Dewar invented a thermal
insulated container
to carry out his research,
and scientists to this day
still call it a Dewar Flask.
Now, let's
see what happens.
[crack! ploof!]
(Kostas Gavroglu) This
phantasmagoric aspect of science
always helped science to be
accepted by the public.
Though it is a little
mystifying, it did play a role
of having society,
having the public accept
that these weird people
in the laboratories
are doing truly interesting,
if not magical things.
(narrator)
Dewar's dream was
to take on the mantle
of the Royal Institution's
greatest scientist,
Michael Faraday.
Seventy years earlier,
Faraday had done experiments
showing that under pressure,
gases like chlorine
and ammonia liquefy.
He was curious to see if
this method of pressurizing
gases into liquids could be used
for all gases.
But some, what he called
the "permanent" gases;
oxygen, nitrogen, hydrogen,
would not liquefy
no matter how much pressure
he applied.
So he abandoned
this line of research.
(as Dewar)
Faraday's was a mind
full of subtle powers,
of divination
into nature's secrets...
and although unable to liquefy
the permanent gases,
he expressed faith
in the potentialities
of experimental inquiry.
The lowest point of temperature
attained by Faraday...
was -130 degrees Centigrade.
(narrator)
It was not until 1873 that
a Dutch theoretical physicist,
Van Der Waals, finally explained
why these gases were
not liquefying.
By estimating
the size of molecules
and the forces between them,
he showed that to liquefy
these gases using pressure,
they each had to be cooled below
a critical temperature.
At last, he had shown
the way to liquefy
the so-called permanent gases
was to cool them.
Oxygen was first,
and then nitrogen,
reaching a new low temperature
of almost -200 degrees
Centigrade.
(as Dewar)
Only the last of the permanent
gases remains to be liquefied,
hydrogen, in the vicinity
of -250 degrees centigrade.
It will be the greatest
achievement of our age,
a triumph of science.
(narrator)
Dewar was determined
to be the first to ascend
what he called "Mount Hydrogen,"
but he was not alone.
The competitor Dewar feared most
was a brilliant Dutchman,
Heike Kamerlingh Onnes.
(Simon Schaffer)
Kamerlingh Onnes
was younger than Dewar
and to a certain extent
looked up to the Scotsman
as his senior.
Dewar didn't have the same,
if you'll pardon
the expression, "warm feelings,"
towards his rival
in the race for cold.
(narrator)
Dewar recognized
that Kamerlingh Onnes
had a new radical approach
to science
and was planning
an industrial scale lab.
(Dirk van Delft)
When Onnes took over
the physics laboratory
in Leiden,
he was only 29 years old.
And, well, he gave
his inaugural address
here in this lecture room,
the big lecture room
of the Academy Building
of Leiden University,
and it was all there.
He was explaining what to
do in the next years,
and he was talking
about liquefying gases,
making Dutch physics
famous abroad, and well,
it was amazing how farsighted
all those visions were.
(narrator)
Kamerlingh Onnes' lab
was more like a factory.
He recruited instrument makers,
glassblowers,
and a cadre of young assistants
who became known
as "blue boys"
because of their blue lab coats.
Later, he set up
a technical training school,
which still exists to this day.
Dewar and Onnes could not have
been more different.
Dewar was
very secretive about his work,
hiding crucial parts
of apparatus from public view
before his lectures.
Onnes on the other hand,
openly shared his lab's
steady progress
in a monthly journal.
Onnes was the tortoise
to Dewar's hare.
In the case of Dewar, you had
a brilliant experimenter,
a person who could actually
build the instruments himself,
and a person who really believed
in the brute force approach,
and that is,
have your instruments,
set up your experiment,
and try as hard as you can,
and then, you'll get
the results you want to get.
In the case of Kamerlingh Onnes,
you have a totally
different approach.
He's the beginning
of what later on
was known as
"big science".
(narrator)
Unlike Dewar, Onnes thought
detailed calculations
based on theory were vital
before embarking on experiments.
He was a disciple and close
friend of Van Der Waals,
whose theory had
helped solve the problem
of liquefying permanent gases.
Though their approaches
were different,
Kamerlingh Onnes and Dewar
used a similar process in their
attempts to liquefy hydrogen.
Their idea was to go
step-by-step down a cascade
using a series
of different gases
that liquefy
at lower and lower temperatures.
By applying pressure
on the first gas
and releasing it into a cooling
coil submerged in a coolant,
it liquefies.
When this liquefied gas
enters the next vessel,
it becomes the coolant
for the 2nd gas in the chain.
When the next gas is pressurized
and passes
through the inner coil,
it liquefies and is
at an even lower temperature.
The 2nd liquid goes on
to cool the next gas and so on.
Step by step, the liquefied
gases become colder and colder.
Each one is used to lower
the temperature of the next gas
sufficiently for it to liquefy.
In the final stage,
where hydrogen gas is cooled,
the idea was to put it
under enormous pressure,
180 times atmospheric pressure,
and then suddenly release it
through a valve.
This would trigger
a massive drop in temperature,
sufficient to turn hydrogen gas
into liquid hydrogen
at -252 degrees, just 21 degrees
above absolute zero.
Here was the risky bit
because his apparatus was
going down in temperature
getting very, very cold.
So very fragile, quite easy
to fracture.
While at the same time,
the pressures he was working at
were very, very high,
so the possibility of explosion.
He took the most amazing risks,
both with himself--
he was a lion of a man
in terms of courage--
and with those around him.
All the equipment
he was working with
could have crumbled or blown up
and more than
occasionally, it did.
[loud explosion]
(narrator)
Dewar had many explosions
in his lab.
Several times,
assistants lost an eye
as shards of glass
catapulted through the air.
He had a notebook.
He actually writes,
jots down many details of what
happened to the apparatus,
but not what happened
to his assistants.
So somehow you get the
impression that apparatus
is more important
than the assistants.
(narrator)
Over in Leiden, Onnes was
facing anxious city officials
who were so worried
about the risk of explosions
that they ordered the lab
to be shut down.
Dewar wrote a letter of protest
on behalf of Onnes...
but the Leiden lab remained
closed for 2 years.
(Dirk van Delft)
Onnes had to wait
and to wait and to wait.
Dewar was already starting
his liquefying hydrogen,
and Onnes had the apparatus
to do so too,
but he just couldn't start,
so we had lost the battle
before it was even begun.
The year is 1898.
Dewar has been working on
trying to liquefy hydrogen
for more than 20 years,
and he's finally ready
to make the final assault
on Mount Hydrogen.
(narrator)
By using liquid oxygen, they
brought down the temperature
of the hydrogen gas
to -200 degrees Celsius.
They increased the pressure till
the vessels were almost bursting
and then opened the last valve
in the cascade.
(as James Dewar) Shortly after
starting, the nozzle plugged,
but it got free by good luck
and almost immediately drops
of liquid began to fall
and soon accumulated
20 cubic centimeters.
(narrator) Dewar had
liquefied hydrogen,
the last of the so-called
permanent gases.
To prove it, he took
a small tube of liquid oxygen
and plunged it into
the new liquid.
Instantly, the liquid oxygen
froze solid.
Now he was convinced.
He had produced the coldest
liquid on earth
and had come closer to
absolute zero than anyone else.
(Tom Shachtman)
Dewar thought that he had done
the most amazing feat
of science in the world,
that he would be immediately
celebrated for it
and get whatever prizes
there were available.
And that didn't happen.
I think for Dewar, it was
the ambition of a mountaineer.
You've climbed
the highest mountain peak
that you can see
in the range around you,
and just as you get
to the top of the peak,
there's an even higher mountain
just beyond.
(narrator)
That new mountain was helium,
a recently discovered inert gas
that was originally thought
only to exist on the sun.
Van Der Waal's theory predicted
helium would liquefy
at an even lower temperature
than hydrogen,
at around 5 degrees
above absolute zero.
Now all Dewar had to do
was obtain some.
It should not have been
difficult.
The two chemists who had
discovered the inert gases,
Lord Rayleigh
and William Ramsay,
often worked together
in the lab next door.
Unfortunately, Dewar had made
enemies of both of them
by refusing to collaborate and
belittling their achievements,
so they had no desire
to share their helium.
Kamerlingh Onnes was faced
with the same problem as Dewar,
which was where can I get
a supply of helium gas?
And he actually asked Dewar
to try and collaborate
with him too, and Dewar said,
I'm having such a problem
getting the gas by myself,
I can't possibly give you any.
I'd like to, but I can't.
(narrator)
Eventually,
each found a supply,
but Onnes' industrial approach
paid dividends.
After 3 years, he had amassed
enough helium gas
to begin experiments.
The tortoise was beginning
to pull away from the hare.
At the same time, Dewar was
running out of resources.
To make matters worse,
a lab assistant
turned a knob the wrong way
releasing a whole canister
of helium into the air.
For 6 months,
the lab couldn't do any work.
(Kostas Gavroglu)
At one point, Dewar
writes to Kamerlingh Onnes
telling him that he is not
in the race anymore.
He thinks that the problems
for liquefying helium
are such that he's not able
to complete the job.
The battlefields of science
are the centers
of a perpetual warfare
in which there is no hope
of a final victory.
To serve
in the scientific army,
to have shown the initiative
is enough to satisfy
the legitimate ambition
of every earnest student
of nature.
Thank you.
[steady ringing]
(narrator)
In the summer of 1908,
Onnes summoned
his chief assistant Flim
from across the river.
They were finally ready
to try to liquefy helium.
At 5:45 on the morning
of July the 10th,
he assembled his team
at the lab.
They had rehearsed the drill
many times before.
Leiden was
a small university town
and the word quickly spread
that this was the big day.
It took until lunchtime
to make sure
the apparatus was purged
of the last traces of air.
By 3 in the afternoon,
work was so intense
that when his wife arrived
with lunch,
he asked her to feed him
so he didn't have to stop.
At 6.30 in the evening,
the temperature began to drop
below that of liquid hydrogen.
But then it seemed to stick.
(Tom Shachtman)
Onnes doesn't know why this is,
and a colleague comes in
and he suggests that
that means maybe
they've actually succeeded
and they don't even know it yet.
So Onnes takes an electric lamp
type thing and he goes
underneath the apparatus
and looks, and sure enough,
there in the vial is this liquid
sitting there quietly.
It's liquefied helium.
(narrator)
They had reached
-268 degrees Celsius,
just 5 degrees
above absolute zero
and finally produced
liquid helium.
This monumental achievement
eventually won Onnes
the Nobel Prize.
When James Dewar heard
that he had lost the race
to Kamerlingh Onnes,
it reignited
a festering resentment.
Dewar berated his
long-suffering assistant Lennox
for failing
to provide enough helium,
only this time,
Lennox had had enough.
He walked out of
the Royal Institution vowing
never to return until Dewar was
dead... and he kept his word.
For Dewar, it was the end
of his low temperature research.
James Dewar's dream of reaching
absolute zero was over.
Although he had won the first
race to liquefy hydrogen,
it never attracted the same
accolades as liquefying helium.
He abandoned
low temperature physics
and moved on
to investigate other phenomena
such as the science
of soap bubbles.
(Simon Schaffer)
I think it's really impressive
how often
scientists do seem to be driven
by the spirit of competition,
by the spirit
of getting there first.
But what's really fascinating
about these races,
the race for absolute zero,
is that the goalposts move
as you're playing the game.
The race in science is not
for a predetermined end,
and once you're there,
the story's over,
the curtain comes down.
That's not at all
what it's like.
Rather, it turns out you find
things you didn't expect.
Nature is cunning,
as Einstein would have said,
and she is constantly
posing a new challenge,
unanticipated by those people
who start out on the race.
(narrator)
This is just what happened
in Leiden
as Onnes' team began
to investigate how materials
conduct electricity
at very low temperatures.
They observed in a sample
of mercury
that at around 4 degrees
above absolute zero,
all resistance to the flow of
electricity abruptly vanished.
Onnes later invented a word
to describe this new phenomenon.
He called it
"superconductivity."
(Allan Griffin)
We have a circular ring
of permanent magnets,
which are producing
a magnetic field.
And now when we put a
superconducting puck over it
and give it a little push,
the magnetic field
repels the superconductor.
(narrator) The magnetic field
from the track
induces a current
in the superconducting puck,
which in turn creates an
opposite magnetic field
that makes the puck levitate.
It produces
a magnetic field
like a north pole
against North Pole,
and that's why you have
the repulsion.
(narrator)
As the puck warms up,
its superconducting
properties vanish
along with its
magnetically induced field.
For decades after
its discovery in 1911,
the underlying cause of
superconductivity
remained a mystery.
Every major physicist, every
major theoretical physicist
had his own theory
of superconductivity.
Everybody tried to solve it,
but it was unsuccessful.
(narrator)
There were more surprises ahead.
In the 1930s,
another strange phenomenon
was observed
at even lower temperatures.
This rapidly evaporating
liquid helium cools
until at 2 degrees
above absolute zero,
a dramatic transformation
takes place.
(Allan Griffin)
Suddenly you see that
the bubbling stops
and that the surface
of the liquid helium
is completely still.
The temperature is
actually being lowered
even further now, but nothing
particularly is happening.
Well, this is really one
of the great phenomenon
in 20th-century physics.
(narrator)
The liquid helium
had turned into a superfluid,
which displays
some really odd properties.
Here I have a beaker
with an unglazed ceramic bottom
of ultrafine porosity.
(narrator)
Ordinarily, this container
with tiny pores
can hold liquid helium,
but the moment the helium turns
superfluid, it leaks through.
(man)
We call this kind
of flow a "superflow."
(narrator)
Superfluid helium can do things
we might have
believed impossible.
It appears to defy gravity.
A thin film can climb walls
and escape its container.
This is because a superfluid
has zero viscosity.
It can even produce a
frictionless fountain,
one that never stops flowing.
Superfluidity and
superconductivity
were baffling concepts
for scientists.
New radical theories were needed
to explain them.
In the 1920s, quantum theory
was emerging as the best hope
of understanding
these strange phenomenon.
Its central idea was that atoms
do not always behave
like individual particles.
Sometimes they merge together
and behave like waves.
They can also be particles
and waves at the same time.
Even for great minds
like Albert Einstein,
this strange paradox
was hard to accept.
In 1925, a young Indian
physicist, Satyendra Bose,
sent Einstein a paper
he'd been unable to publish.
Bose had attempted to apply
the mathematics of how light
particles behave to whole atoms.
Einstein realized
the importance of this concept
and did some
further calculations.
He predicted that on reaching
extremely low temperatures,
just a hair above absolute zero,
it might be possible
to produce a new state of matter
that followed quantum rules.
It would not be a solid
or liquid or gas.
It was given a name almost
as strange as its properties--
a Bose-Einstein condensate.
For the next 70 years,
people could only dream
about making such a condensate,
which has never been seen
in nature.
Matter can exist
in various states.
Atoms at high temperature
always form gases.
If you cool the gas,
it becomes a liquid.
If you cool the liquid,
it becomes a solid.
But under certain circumstances,
if you cool atoms far enough
to extremely low temperatures,
they undergo
a very strange transformation.
They undergo an identity crisis.
So let me show you what I mean
by "an identity crisis."
When you go to low
temperatures, the
quantum mechanical properties
of the atoms become important.
These are very strange,
very unfamiliar to us,
but in fact, each one
of these atoms
starts to display
wavelike properties.
So instead of points like that,
you have little wave packets,
like that, moving around.
It's really difficult for me
to explain just why that is,
but that's the way it is.
Now, as you go
to very low temperatures,
the size of these packets gets
longer and longer and longer.
And then suddenly,
if you get them cold enough,
they start overlapping,
and when they overlap,
the system behaves
not like individual particles,
but particles which have
lost their identity.
They all think
they're everywhere.
This little wave packet
over here can't tell
whether it's this one
or that one or that one.
Or that one
or that one or that one.
It's there, and it's
there, and it's there.
They're all in one great big
quantum state.
They're all overlapping.
They're all doing
the same thing,
and what they're doing,
to a good approximation is,
they're simply
sitting at rest.
This Bose-Einstein
condensate is
very difficult to imagine
or to visualize.
I could imagine what
it's like to be an atom
running around gaily, freely,
bouncing into things,
sometimes going fast,
sometimes going slow,
but in the Bose condensate,
I'm everywhere at once.
I've lost my identity.
I don't know who I am anymore.
I'm at rest, and all the other
atoms around are at rest.
But there are not
other atoms around.
We're all just one
great big quantum system.
There's nothing else
like that in physics
and certainly not
in human experience.
So just to think about this
causes me wonder and confusion.
Dan Kleppner and his MIT
colleague Tom Greytak began
to try to make a Bose-Einstein
condensate in hydrogen.
(Dan Kleppner)
As we started out the search
for Bose-Einstein condensation,
our enthusiasm grew
because hydrogen seemed
like such
a wonderful atom to use.
It had everything going for it.
It had its light mass.
That means that
the atoms will condense
at a higher temperature
than other atoms would.
The atoms interact with
each other very, very weakly.
All the signals seem to be
pointing to the fact
that hydrogen was the atom
for getting
to Bose-Einstein condensation.
(narrator)
Kleppner's idea was
to cool the hydrogen atoms
by making use
of their magnetic poles.
He used a strong magnetic field
to create a cluster
of atoms in a cold trap.
Unfortunately, sometimes
one atom flipped another,
which triggered
a release of energy
that raised the temperature.
[sighs] It was
a frustrating time for us
because our methods
were so complicated
we were having a hard time
moving forwards.
(narrator)
Now others decided
to take up the challenge.
Two physicists from MIT
met in Boulder, Colorado
and came up with a different
approach to the problem.
Rather than focusing on
the lighter atoms
of the periodic table,
they hit upon
the idea of using
much heavier metallic atoms,
like rubidium and caesium.
But would using
these giants enable them
to reach closer
to absolute zero?
The idea in the field
in those days was that
the light things like hydrogen
and lithium would be easier,
and there are some good
reasons for thinking that.
But we had other ideas.
Yeah, sort of gut intuition
in some sense.
(narrator)
Their plan was to use
a laser beam to cool the atoms,
a technique that had already
been tried by physicists at MIT.
Lasers are usually associated
with making things hot,
but if they are tuned
to the same frequency as atoms
traveling at a particular speed,
lasers can cool them down.
When the stream of
light particles from the laser
hits the selected atoms
in the gas cloud,
they slow down
and become cold.
Laser cooling was a new tool
that had the potential
to reduce
the temperature of a gas
to within a few millionths
of a degree of absolute zero.
But Cornell and Weiman were not
the only ones excited
by this prospect.
A new scientist
had arrived at MIT.
(Wolfgang Ketterle)
It was in late '91 or early '92
that we had an idea,
an idea how a different
arrangement of laser beams
would be able to cool atoms
to higher density.
And it worked!
And this was
really a trigger point.
I will never forget the
excitement in those groups,
group meetings, when we
discussed what will be next,
because with higher density,
there are
many things you can do.
Could we now push
to Bose-Einstein condensation?
I see, well, lots
of cables and electronics...
(narrator)
All the resources of Ketterle's
lab were redirected
to make a condensate
in sodium atoms.
And right here, this
is an atomic beam oven.
What is wrapped in tinfoil
is a little vacuum chamber
where we heat up
metallic sodium,
so the metallic sodium
melts and evaporates,
and it's ultimately
the sodium vapor,
the sodium atoms, which we tried
to Bose-Einstein condense.
(narrator)
MIT, Boulder, and several other
labs were chasing the same goal.
It had echoes of the race
to produce liquid helium
almost a century earlier.
(Eric Cornell)
As I tell my students today,
anything worth doing
is worth doing quickly,
because science
moves on and...
we're all mortal
and you want to do things.
(narrator)
While MIT was installing
its sophisticated lasers,
Carl Weiman's approach was
"small is beautiful".
(Eric Cornell)
In some cases, he was
ripping open old fax machines
and taking out
the little chip inside
that made the laser and showed
that you could take these lasers
and put them into a home-built
piece of apparatus,
stabilize the laser,
and use them
to do spectroscopy
and laser cooling.
(Carl Weiman)
This is actually our first,
what's called
a "vapor cell optical trap."
You can see it's kind of
this old cruddy thing
pulled together glass where we
could send laser beams in
from all the different
directions
and have just a little bit of
the atoms we wanted to cool.
(narrator)
As well as bombarding
the atoms with lasers,
they also trapped them
in a strong magnetic field.
We would try this
sort of magnetic trap,
that sort of magnetic trap,
this sort of imaging,
that sort of imaging,
that sort of cooling.
All those things we could do
without building a whole
new chamber each time.
We tried literally
4 different magnetic traps
in 4 years
instead of having
a 3 or 4-year construction
project for each one.
(narrator)
By being fast and flexible,
the Boulder group hoped to beat
their old lab at MIT,
but MIT had its own plans.
(Wolfgang Ketterle)
There was a sense
of competition,
but it was what I would call
friendly competition.
I mean, can you imagine
2 athletes;
they are in
the same training camps,
they help each other, they even
give tips to each other,
but then when it comes
to the race,
everybody wants to be the first.
The rival groups
were both using
magnetic trapping and lasers
to cool their atoms,
but for the final push
towards absolute zero
to turn these atoms of gas
into the quantum state
Einstein had predicted,
they needed one more cooling
technique-- evaporative cooling.
It's just like with this coffee;
the steam coming off the coffee
is the hottest
of the coffee molecules
escaping and carrying away more
than their fair share of energy.
In the case of the atoms,
we keep the atoms in
a sort of magnetic bowl,
and we confine the atoms there.
They zoom around inside the
bowl, and then the hottest ones
have enough energy to roll up
the side of the bowl
and fall over the edge,
slop over the edge,
taking away with them much more
than their fair share of energy.
And the atoms that remain have
less and less energy,
which means they move
slower and slower
and start to cluster
near the bottom.
And as that happens,
we gradually lower the edges
of the magnetic trap
and always so there's just
a few atoms that can escape,
until finally
the remaining atoms cluster
near the bottle of the bowl,
huddle together,
they get colder and colder
and denser and denser
and eventually in this way,
evaporation forces
the Bose-Einstein
condensation to occur.
(narrator)
The race to produce
a Bose-Einstein condensate
was intensifying.
At every major meeting,
Eric Cornell and I gave talks
or talked to each other.
We were keenly aware
that we were
both working
towards the same goal.
(narrator)
In June 1995, the Boulder group
was working 'round the clock
knowing that MIT
and several other labs
were also poised to produce
the first condensate.
An official visit from a
government-funding agency
was the last thing they needed.
We didn't want to
close down the lab
or clean up our lab
or put up posters.
We wanted to
work very hard.
So the senior dignitaries
in the 3-piece suits and so on
came into the lab,
and we left the lights off,
and everyone
continued to work,
and I made them keep
their voices down.
And talked to them
rather in a hurried way
and then sort of
shuffled them out the door,
and they all had a slightly
puzzled look on their face
'cause it probably had never
happened to them before
in their history of being
a visiting committee,
that they were treated with
as little...little pomp.
And later, I actually met
one of the guys who said,
I suspected something
was up that day
because otherwise you never
would've dared to do that.
(narrator) June the 5th, 1995
turned out to be a big day
in the history of physics.
The Boulder group seemed to
have made what Einstein had
theorized 70 years before--
a Bose-Einstein condensate.
Our first reaction was wait, we
gotta be careful here, you know.
Let's think of all the different
knobs we can turn,
checks we can make and so on
to see if this really is
Bose-Einstein condensation.
(Eric Cornell)
A condensate is
sort of like a vampire.
If the sunlight even once
falls on it, it's dead,
and so it its realm
is the realm of the dark.
But we can take
pictures of them
because we strobe
the laser light really fast,
and even as the condensate's
dying, it casts a shadow,
and the shadow is
frozen in the film.
(narrator)
At a temperature of
170 billionth of a degree
above absolute zero,
Weiman and Cornell created
a pure Bose-Einstein condensate
in a gas cloud
of just 3000 atoms
of rubidium,
the first in the universe,
as far as we know.
One of the first things
you need to understand
about Bose-Einstein condensation
is how very, very cold it is.
Where we live,
at room temperature,
is far above absolute zero
in the scale.
Imagine that room temperature
is represented by London,
thousands of kilometers
from here.
Then on that scale, if we
imagine right here
where I'm standing in Boulder
is absolute zero,
the coldest possible
temperature,
then how close are we
to absolute zero?
If we think of London
as being room temperature
and right where I am
is absolute zero,
then Bose-Einstein
condensation occurs just
the thickness of this pencil
lead away from absolute zero.
(narrator) Within months of
the Boulder group's success,
Wolfgang Ketterle produced
an even larger condensate
from half a million sodium atoms
slowed down to a virtual
standstill,
causing their wave functions
to overlap
to produce an entirely new
state of matter.
At last quantum mechanics
was more than just
a theoretical construct.
It was something that could be
seen with the naked eye.
Cornell, Ketterle & Weiman
shared the Nobel Prize
for physics in 2001.
(Carl Weiman)
One of the things
Nobel Prize means
and the ceremony means is
that everybody remembers
Eric's the person
who forgot
to bow to the king!
There was a breakdown
of protocol on my part.
There was no excuse because
they actually drill us.
It's more like a--we have
a series of rehearsals
practicing how to bow to the
king, and I somehow managed
to bollocks it up at
the last possible moment.
And I thought maybe,
you know,
Carl who came after me would do
this, make the same mistake,
and then no one would figure it
out, but no, he was perfect.
(Wolfgang Ketterle)
I heard about the Nobel Prize
when I was
woken up by a telephone call,
which was at, I think,
5:30 in the morning.
So you wake up, you go
to the telephone,
and somebody tells you,
"Congratulations,
you have won the Nobel Prize."
You're still tired, your brain
is not fully functional,
but you realize this is big
and what you feel is,
you know, pride,
pride for MIT, your
collaborators, for yourself.
It's wonderful to see that
your work gets recognized
and acknowledged in this way.
(narrator)
Like any great adventure,
the pursuit of science offers
no guarantee of success.
But for the godfather
of ultra cold atoms,
persistence eventually paid off.
In 1998, after 20 years
of struggling
to obtain a condensate
in hydrogen,
Dan Kleppner finally succeeded.
For a few fleeting moments,
his dream came true.
(Daniel Kleppner)
Of course, we were delighted,
and I think everyone
was delighted
because we'd been working
on it for so long.
It's kind of embarrassing to
have this group,
which helped start the work
and was working away there,
fruitlessly, while everyone
was enjoying success.
When we got it,
everyone was happy.
(Wolfgang Ketterle)
To see that an effort,
which lasted for 20 years,
which took so much patience,
frustration and tenacity,
to see that succeed is just
emotional. It's liberating.
I will never forget
the standing ovation,
which Dan Kleppner received at
the Verena Summer School
when he announced Bose-Einstein
condensation in hydrogen.
Everybody just got up and gave--
it was
sort of like an opera where
everybody just cheered,
[with emotion] and people were
crying, because everybody
realized that they had finished
the race, but too late,
and it wasn't gonna work out,
but in some sense,
they had really stimulated
the whole field.
So it was a very, very moving,
very moving moment.
(narrator)
For the pioneers who had
realized Einstein's dream
and created condensates, it was
the end of an extraordinary
decade of physics.
Now, there was
a new challenge--
to work out
what to do with them.
At Harvard, a Danish scientist,
Lene Hau,
had the idea of using a
condensate to slow down light.
We all have this sense, you
know, light is something that--
nothing goes faster than light,
in vacuum,
and if somehow we could use
this system
to get light down to,
you know, to a human level,
I thought that was just
absolutely fascinating.
(narrator)
Lene Hau created a cigar-shaped
Bose-Einstein condensate
to carry out her experiment.
She fired a light pulse
into the cloud.
The speed of light is around
186,000 miles per second,
but when the pulse
hits the condensate,
it slows down
to the speed of a bicycle.
(Lene Hau)
So light pulse might start out
being 1 to 2 miles long
in free space,
it goes into our medium,
and since the front edge enters
first that will slow down.
The back end is still in free
space, that'll catch up,
and that'll create that
compression.
And it'll end up being
compressed
from 1 to 2 miles down
to 0.001 micron
or even smaller than that.
You could say well, gee,
it's easy to stop light
because I could just send
a laser beam into a wall
and I would stop it.
Well, the problem is,
you lose the information
because it turns into heat.
You can never get that
information back.
In our case, when we stop it,
the information is not lost
because that's stored
in the medium,
then we have time
to revive it,
the system has
all the information
to revive the light pulse,
and it can move on.
(narrator)
One day, ultra cold atoms
will probably be used
to store
and even process information.
Even now,
cold atoms are being
turned into prototype
quantum computers.
(Seth Lloyd)
As a quantum mechanic,
I engineer atoms.
To make a computer out of atoms,
you have to somehow get atoms
to register information
and then to process it.
Why build quantum computers?
Because they're cool, it's fun,
and we can do it. Right?
I mean, we actually can
take atoms
and if we ask them nicely,
they'll compute.
That's a lot of fun.
I mean, have you ever
talked to an atom recently and
had it talk back? It's great!
(narrator)
Unlike ordinary computers
where each decision is based
around a bit of information
and is either a zero or a one,
in the quantum world,
the rules change.
At first glance,
a quantum computer
looks almost exactly the same.
But quantum mechanics
is weird.
It's funky, okay?
It's weird.
(Peter Shor)
When you do quantum computing,
you want to make
this weirdness work for you.
So now let's look at our
quantum bit or Q bit.
The Q bit can not only be a zero
or a one, it can also both be...
A zero and one
(both) at the same time.
It's almost like a form
of parallel computation,
If you look at
the mini worlds
but in the parallel computer,
interpretation
of a quantum computer,
one processor does this,
one processor does that,
your quantum computer
so you have 2 processors
doing this and that.
is doing many,
In a quantum computer,
you have
many computations
only one processor doing
all at the same time.
this and that
at the same time.
[both laugh]
(narrator)
Today, computers are limited
in the amount of information
they can handle
by the heat
and number of the circuits.
Here, within a giant Dewar Flask
lies a prototype
quantum computer
surrounded by its supercooled,
superconducting magnet.
In the future, quantum computing
could be used to predict
incredibly complex
quantum interactions,
such as how a new drug acts
on faulty biochemistry.
Or to solve
complex encryption problems,
like decoding prime numbers
that are the key
to Internet security.
Already, supercooled quantum
devices are mapping
the magnetic activity
of the brain.
Often, the promised benefits
from a scientific breakthrough
take a long time to emerge.
Many predicted that
by this century,
energy saving superconducting
power lines
and maglev bullet trains
would be crisscrossing
the continents.
Perhaps as world energy supplies
decline, these technologies,
once seen as too costly,
will start to take off.
This weird quantum world is
part of a new frontier
opened up by the descent
towards absolute zero.
It's been a remarkable journey
for scientists
into unknown territories
far beyond
the narrow confines of earth.
On the Kelvin temperature scale,
which begins at absolute zero,
the temperature of the sun
is around 5000 Kelvin.
At 1000 Kelvin, metals melt.
At 300, we reach what we think
of as room temperature.
Air liquefies at 100 Kelvin,
hydrogen at 20,
helium at 4 Kelvin.
The deepest outer space is
3 degrees above absolute zero.
But the descent
doesn't stop there.
With ultra cold refrigerators,
the decimal point
shifts 3 places
to a few 1000ths of a degree,
and laser cooling takes it down
3 more places
to a millionth of a degree,
the temperature of
a Bose-Einstein condensate.
With magnetic cooling,
we shift 4 more decimal places
until we reach the coldest
recorded temperature
in the universe,
created at a lab in Helsinki,
100 pico Kelvin,
or a 10th of a billionth
of a degree above absolute zero.
So will it ever be
possible to go all the way,
to reach the Holy Grail of cold,
zero Kelvin?
(Seth Lloyd)
Getting to absolute zero
is tough. [laughs]
Nobody's actually been there
at absolute 0.000000...
with an infinite number 0s.
That last little
tiny bit of heat
becomes harder and harder
to get out, and in particular,
the time scales
for getting it out
get longer and longer
and longer
the smaller and smaller
the amounts of energy involved.
So eventually, if you're
talking about extracting
an amount of energy
that's sufficiently small,
it would indeed take the age
of the universe to do it.
Also, actually, you'd
need an apparatus
the size of the universe to do
it, but that's another story!
(narrator)
Absolute zero may be
unreachable,
but by exploring
further and further
towards this ultimate
destination of cold,
the most fundamental secrets
of matter have been revealed.
If our past was defined
by our mastery of heat,
perhaps our future lies in
the continuing conquest of cold.
Text : WTC-SWE
(male narrator)
The greatest triumph
of civilization
is often seen as
our mastery of heat.
Yet our conquest of cold
is an equally epic journey
from dark beginnings
to an ultra cool frontier.
In the last 100 years,
cold has transformed
the way we live and work.
Imagine supermarkets without
refrigeration or frozen food,
skyscrapers
without air-conditioning,
hospitals without MRI machines
or liquid oxygen.
We take for granted
the technology of cold,
yet it has enabled us
to explore outer space
and the inner depths
of our brain.
And as we develop new
ultra cold technology
to create quantum computers
and high-speed networks,
it will change
the way we work and interact.
By the late 19th century,
the ultimate extreme of cold
had a number,
-273 degrees Celsius,
and a name..."Absolute Zero."
A frontier so enticing
that rival physicists
from all over Europe
began a race
towards this absolute
limit of cold.
It was a high-stakes pursuit,
one that continues
even now as we explore
a strange quantum world
where fluids
appear to defy gravity
and electricity flows freely
without resistance.
"The race for Absolute Zero,"
up next on "NOVA."
(narrator)
A century ago, Antarctic
explorers were pushing
further and further towards
the coldest place on Earth,
the South Pole,
where temperatures
can plummet to -80 degrees.
The competition to reach
this goal was matched by
a less publicized, but equally
daunting scientific endeavor,
the attempt to reach
the coldest point
in the universe--absolute zero.
Was it possible to attain this
ultimate limit of temperature,
-273 degrees Celsius?
Only in a laboratory
by liquefying gases
could scientific adventurers
take the first steps
towards this Holy Grail,
a place where atoms come
to a virtual standstill,
utterly drained
of all thermal energy.
Among the front-runners in
the race towards absolute zero
was James Dewar, a professor at
the Royal Institution in London.
(man, as James Dewar)
It will be the greatest
achievement of our age.
(narrator)
In 1891, he gave
one of his celebrated
Friday night public lectures
on the wonders of the super cold
to celebrate the centenary
of his great predecessor,
Michael Faraday.
The descent to a temperature
within 5 degrees of zero
would open up new vistas
of scientific inquiry,
which would add immensely
to our knowledge
of the properties
of matter.
James Dewar is a canny
and I think very ambitious,
practically-minded
Scottish scientist.
He could really show
both his colleagues
and the fee-paying audiences
some of the secrets of nature.
Take this rubber ball...
it bounces well,
I think you'll agree.
But let's see what happens
after a few seconds' immersion
in liquid oxygen.
(narrator)
Dewar invented a thermal
insulated container
to carry out his research,
and scientists to this day
still call it a Dewar Flask.
Now, let's
see what happens.
[crack! ploof!]
(Kostas Gavroglu) This
phantasmagoric aspect of science
always helped science to be
accepted by the public.
Though it is a little
mystifying, it did play a role
of having society,
having the public accept
that these weird people
in the laboratories
are doing truly interesting,
if not magical things.
(narrator)
Dewar's dream was
to take on the mantle
of the Royal Institution's
greatest scientist,
Michael Faraday.
Seventy years earlier,
Faraday had done experiments
showing that under pressure,
gases like chlorine
and ammonia liquefy.
He was curious to see if
this method of pressurizing
gases into liquids could be used
for all gases.
But some, what he called
the "permanent" gases;
oxygen, nitrogen, hydrogen,
would not liquefy
no matter how much pressure
he applied.
So he abandoned
this line of research.
(as Dewar)
Faraday's was a mind
full of subtle powers,
of divination
into nature's secrets...
and although unable to liquefy
the permanent gases,
he expressed faith
in the potentialities
of experimental inquiry.
The lowest point of temperature
attained by Faraday...
was -130 degrees Centigrade.
(narrator)
It was not until 1873 that
a Dutch theoretical physicist,
Van Der Waals, finally explained
why these gases were
not liquefying.
By estimating
the size of molecules
and the forces between them,
he showed that to liquefy
these gases using pressure,
they each had to be cooled below
a critical temperature.
At last, he had shown
the way to liquefy
the so-called permanent gases
was to cool them.
Oxygen was first,
and then nitrogen,
reaching a new low temperature
of almost -200 degrees
Centigrade.
(as Dewar)
Only the last of the permanent
gases remains to be liquefied,
hydrogen, in the vicinity
of -250 degrees centigrade.
It will be the greatest
achievement of our age,
a triumph of science.
(narrator)
Dewar was determined
to be the first to ascend
what he called "Mount Hydrogen,"
but he was not alone.
The competitor Dewar feared most
was a brilliant Dutchman,
Heike Kamerlingh Onnes.
(Simon Schaffer)
Kamerlingh Onnes
was younger than Dewar
and to a certain extent
looked up to the Scotsman
as his senior.
Dewar didn't have the same,
if you'll pardon
the expression, "warm feelings,"
towards his rival
in the race for cold.
(narrator)
Dewar recognized
that Kamerlingh Onnes
had a new radical approach
to science
and was planning
an industrial scale lab.
(Dirk van Delft)
When Onnes took over
the physics laboratory
in Leiden,
he was only 29 years old.
And, well, he gave
his inaugural address
here in this lecture room,
the big lecture room
of the Academy Building
of Leiden University,
and it was all there.
He was explaining what to
do in the next years,
and he was talking
about liquefying gases,
making Dutch physics
famous abroad, and well,
it was amazing how farsighted
all those visions were.
(narrator)
Kamerlingh Onnes' lab
was more like a factory.
He recruited instrument makers,
glassblowers,
and a cadre of young assistants
who became known
as "blue boys"
because of their blue lab coats.
Later, he set up
a technical training school,
which still exists to this day.
Dewar and Onnes could not have
been more different.
Dewar was
very secretive about his work,
hiding crucial parts
of apparatus from public view
before his lectures.
Onnes on the other hand,
openly shared his lab's
steady progress
in a monthly journal.
Onnes was the tortoise
to Dewar's hare.
In the case of Dewar, you had
a brilliant experimenter,
a person who could actually
build the instruments himself,
and a person who really believed
in the brute force approach,
and that is,
have your instruments,
set up your experiment,
and try as hard as you can,
and then, you'll get
the results you want to get.
In the case of Kamerlingh Onnes,
you have a totally
different approach.
He's the beginning
of what later on
was known as
"big science".
(narrator)
Unlike Dewar, Onnes thought
detailed calculations
based on theory were vital
before embarking on experiments.
He was a disciple and close
friend of Van Der Waals,
whose theory had
helped solve the problem
of liquefying permanent gases.
Though their approaches
were different,
Kamerlingh Onnes and Dewar
used a similar process in their
attempts to liquefy hydrogen.
Their idea was to go
step-by-step down a cascade
using a series
of different gases
that liquefy
at lower and lower temperatures.
By applying pressure
on the first gas
and releasing it into a cooling
coil submerged in a coolant,
it liquefies.
When this liquefied gas
enters the next vessel,
it becomes the coolant
for the 2nd gas in the chain.
When the next gas is pressurized
and passes
through the inner coil,
it liquefies and is
at an even lower temperature.
The 2nd liquid goes on
to cool the next gas and so on.
Step by step, the liquefied
gases become colder and colder.
Each one is used to lower
the temperature of the next gas
sufficiently for it to liquefy.
In the final stage,
where hydrogen gas is cooled,
the idea was to put it
under enormous pressure,
180 times atmospheric pressure,
and then suddenly release it
through a valve.
This would trigger
a massive drop in temperature,
sufficient to turn hydrogen gas
into liquid hydrogen
at -252 degrees, just 21 degrees
above absolute zero.
Here was the risky bit
because his apparatus was
going down in temperature
getting very, very cold.
So very fragile, quite easy
to fracture.
While at the same time,
the pressures he was working at
were very, very high,
so the possibility of explosion.
He took the most amazing risks,
both with himself--
he was a lion of a man
in terms of courage--
and with those around him.
All the equipment
he was working with
could have crumbled or blown up
and more than
occasionally, it did.
[loud explosion]
(narrator)
Dewar had many explosions
in his lab.
Several times,
assistants lost an eye
as shards of glass
catapulted through the air.
He had a notebook.
He actually writes,
jots down many details of what
happened to the apparatus,
but not what happened
to his assistants.
So somehow you get the
impression that apparatus
is more important
than the assistants.
(narrator)
Over in Leiden, Onnes was
facing anxious city officials
who were so worried
about the risk of explosions
that they ordered the lab
to be shut down.
Dewar wrote a letter of protest
on behalf of Onnes...
but the Leiden lab remained
closed for 2 years.
(Dirk van Delft)
Onnes had to wait
and to wait and to wait.
Dewar was already starting
his liquefying hydrogen,
and Onnes had the apparatus
to do so too,
but he just couldn't start,
so we had lost the battle
before it was even begun.
The year is 1898.
Dewar has been working on
trying to liquefy hydrogen
for more than 20 years,
and he's finally ready
to make the final assault
on Mount Hydrogen.
(narrator)
By using liquid oxygen, they
brought down the temperature
of the hydrogen gas
to -200 degrees Celsius.
They increased the pressure till
the vessels were almost bursting
and then opened the last valve
in the cascade.
(as James Dewar) Shortly after
starting, the nozzle plugged,
but it got free by good luck
and almost immediately drops
of liquid began to fall
and soon accumulated
20 cubic centimeters.
(narrator) Dewar had
liquefied hydrogen,
the last of the so-called
permanent gases.
To prove it, he took
a small tube of liquid oxygen
and plunged it into
the new liquid.
Instantly, the liquid oxygen
froze solid.
Now he was convinced.
He had produced the coldest
liquid on earth
and had come closer to
absolute zero than anyone else.
(Tom Shachtman)
Dewar thought that he had done
the most amazing feat
of science in the world,
that he would be immediately
celebrated for it
and get whatever prizes
there were available.
And that didn't happen.
I think for Dewar, it was
the ambition of a mountaineer.
You've climbed
the highest mountain peak
that you can see
in the range around you,
and just as you get
to the top of the peak,
there's an even higher mountain
just beyond.
(narrator)
That new mountain was helium,
a recently discovered inert gas
that was originally thought
only to exist on the sun.
Van Der Waal's theory predicted
helium would liquefy
at an even lower temperature
than hydrogen,
at around 5 degrees
above absolute zero.
Now all Dewar had to do
was obtain some.
It should not have been
difficult.
The two chemists who had
discovered the inert gases,
Lord Rayleigh
and William Ramsay,
often worked together
in the lab next door.
Unfortunately, Dewar had made
enemies of both of them
by refusing to collaborate and
belittling their achievements,
so they had no desire
to share their helium.
Kamerlingh Onnes was faced
with the same problem as Dewar,
which was where can I get
a supply of helium gas?
And he actually asked Dewar
to try and collaborate
with him too, and Dewar said,
I'm having such a problem
getting the gas by myself,
I can't possibly give you any.
I'd like to, but I can't.
(narrator)
Eventually,
each found a supply,
but Onnes' industrial approach
paid dividends.
After 3 years, he had amassed
enough helium gas
to begin experiments.
The tortoise was beginning
to pull away from the hare.
At the same time, Dewar was
running out of resources.
To make matters worse,
a lab assistant
turned a knob the wrong way
releasing a whole canister
of helium into the air.
For 6 months,
the lab couldn't do any work.
(Kostas Gavroglu)
At one point, Dewar
writes to Kamerlingh Onnes
telling him that he is not
in the race anymore.
He thinks that the problems
for liquefying helium
are such that he's not able
to complete the job.
The battlefields of science
are the centers
of a perpetual warfare
in which there is no hope
of a final victory.
To serve
in the scientific army,
to have shown the initiative
is enough to satisfy
the legitimate ambition
of every earnest student
of nature.
Thank you.
[steady ringing]
(narrator)
In the summer of 1908,
Onnes summoned
his chief assistant Flim
from across the river.
They were finally ready
to try to liquefy helium.
At 5:45 on the morning
of July the 10th,
he assembled his team
at the lab.
They had rehearsed the drill
many times before.
Leiden was
a small university town
and the word quickly spread
that this was the big day.
It took until lunchtime
to make sure
the apparatus was purged
of the last traces of air.
By 3 in the afternoon,
work was so intense
that when his wife arrived
with lunch,
he asked her to feed him
so he didn't have to stop.
At 6.30 in the evening,
the temperature began to drop
below that of liquid hydrogen.
But then it seemed to stick.
(Tom Shachtman)
Onnes doesn't know why this is,
and a colleague comes in
and he suggests that
that means maybe
they've actually succeeded
and they don't even know it yet.
So Onnes takes an electric lamp
type thing and he goes
underneath the apparatus
and looks, and sure enough,
there in the vial is this liquid
sitting there quietly.
It's liquefied helium.
(narrator)
They had reached
-268 degrees Celsius,
just 5 degrees
above absolute zero
and finally produced
liquid helium.
This monumental achievement
eventually won Onnes
the Nobel Prize.
When James Dewar heard
that he had lost the race
to Kamerlingh Onnes,
it reignited
a festering resentment.
Dewar berated his
long-suffering assistant Lennox
for failing
to provide enough helium,
only this time,
Lennox had had enough.
He walked out of
the Royal Institution vowing
never to return until Dewar was
dead... and he kept his word.
For Dewar, it was the end
of his low temperature research.
James Dewar's dream of reaching
absolute zero was over.
Although he had won the first
race to liquefy hydrogen,
it never attracted the same
accolades as liquefying helium.
He abandoned
low temperature physics
and moved on
to investigate other phenomena
such as the science
of soap bubbles.
(Simon Schaffer)
I think it's really impressive
how often
scientists do seem to be driven
by the spirit of competition,
by the spirit
of getting there first.
But what's really fascinating
about these races,
the race for absolute zero,
is that the goalposts move
as you're playing the game.
The race in science is not
for a predetermined end,
and once you're there,
the story's over,
the curtain comes down.
That's not at all
what it's like.
Rather, it turns out you find
things you didn't expect.
Nature is cunning,
as Einstein would have said,
and she is constantly
posing a new challenge,
unanticipated by those people
who start out on the race.
(narrator)
This is just what happened
in Leiden
as Onnes' team began
to investigate how materials
conduct electricity
at very low temperatures.
They observed in a sample
of mercury
that at around 4 degrees
above absolute zero,
all resistance to the flow of
electricity abruptly vanished.
Onnes later invented a word
to describe this new phenomenon.
He called it
"superconductivity."
(Allan Griffin)
We have a circular ring
of permanent magnets,
which are producing
a magnetic field.
And now when we put a
superconducting puck over it
and give it a little push,
the magnetic field
repels the superconductor.
(narrator) The magnetic field
from the track
induces a current
in the superconducting puck,
which in turn creates an
opposite magnetic field
that makes the puck levitate.
It produces
a magnetic field
like a north pole
against North Pole,
and that's why you have
the repulsion.
(narrator)
As the puck warms up,
its superconducting
properties vanish
along with its
magnetically induced field.
For decades after
its discovery in 1911,
the underlying cause of
superconductivity
remained a mystery.
Every major physicist, every
major theoretical physicist
had his own theory
of superconductivity.
Everybody tried to solve it,
but it was unsuccessful.
(narrator)
There were more surprises ahead.
In the 1930s,
another strange phenomenon
was observed
at even lower temperatures.
This rapidly evaporating
liquid helium cools
until at 2 degrees
above absolute zero,
a dramatic transformation
takes place.
(Allan Griffin)
Suddenly you see that
the bubbling stops
and that the surface
of the liquid helium
is completely still.
The temperature is
actually being lowered
even further now, but nothing
particularly is happening.
Well, this is really one
of the great phenomenon
in 20th-century physics.
(narrator)
The liquid helium
had turned into a superfluid,
which displays
some really odd properties.
Here I have a beaker
with an unglazed ceramic bottom
of ultrafine porosity.
(narrator)
Ordinarily, this container
with tiny pores
can hold liquid helium,
but the moment the helium turns
superfluid, it leaks through.
(man)
We call this kind
of flow a "superflow."
(narrator)
Superfluid helium can do things
we might have
believed impossible.
It appears to defy gravity.
A thin film can climb walls
and escape its container.
This is because a superfluid
has zero viscosity.
It can even produce a
frictionless fountain,
one that never stops flowing.
Superfluidity and
superconductivity
were baffling concepts
for scientists.
New radical theories were needed
to explain them.
In the 1920s, quantum theory
was emerging as the best hope
of understanding
these strange phenomenon.
Its central idea was that atoms
do not always behave
like individual particles.
Sometimes they merge together
and behave like waves.
They can also be particles
and waves at the same time.
Even for great minds
like Albert Einstein,
this strange paradox
was hard to accept.
In 1925, a young Indian
physicist, Satyendra Bose,
sent Einstein a paper
he'd been unable to publish.
Bose had attempted to apply
the mathematics of how light
particles behave to whole atoms.
Einstein realized
the importance of this concept
and did some
further calculations.
He predicted that on reaching
extremely low temperatures,
just a hair above absolute zero,
it might be possible
to produce a new state of matter
that followed quantum rules.
It would not be a solid
or liquid or gas.
It was given a name almost
as strange as its properties--
a Bose-Einstein condensate.
For the next 70 years,
people could only dream
about making such a condensate,
which has never been seen
in nature.
Matter can exist
in various states.
Atoms at high temperature
always form gases.
If you cool the gas,
it becomes a liquid.
If you cool the liquid,
it becomes a solid.
But under certain circumstances,
if you cool atoms far enough
to extremely low temperatures,
they undergo
a very strange transformation.
They undergo an identity crisis.
So let me show you what I mean
by "an identity crisis."
When you go to low
temperatures, the
quantum mechanical properties
of the atoms become important.
These are very strange,
very unfamiliar to us,
but in fact, each one
of these atoms
starts to display
wavelike properties.
So instead of points like that,
you have little wave packets,
like that, moving around.
It's really difficult for me
to explain just why that is,
but that's the way it is.
Now, as you go
to very low temperatures,
the size of these packets gets
longer and longer and longer.
And then suddenly,
if you get them cold enough,
they start overlapping,
and when they overlap,
the system behaves
not like individual particles,
but particles which have
lost their identity.
They all think
they're everywhere.
This little wave packet
over here can't tell
whether it's this one
or that one or that one.
Or that one
or that one or that one.
It's there, and it's
there, and it's there.
They're all in one great big
quantum state.
They're all overlapping.
They're all doing
the same thing,
and what they're doing,
to a good approximation is,
they're simply
sitting at rest.
This Bose-Einstein
condensate is
very difficult to imagine
or to visualize.
I could imagine what
it's like to be an atom
running around gaily, freely,
bouncing into things,
sometimes going fast,
sometimes going slow,
but in the Bose condensate,
I'm everywhere at once.
I've lost my identity.
I don't know who I am anymore.
I'm at rest, and all the other
atoms around are at rest.
But there are not
other atoms around.
We're all just one
great big quantum system.
There's nothing else
like that in physics
and certainly not
in human experience.
So just to think about this
causes me wonder and confusion.
Dan Kleppner and his MIT
colleague Tom Greytak began
to try to make a Bose-Einstein
condensate in hydrogen.
(Dan Kleppner)
As we started out the search
for Bose-Einstein condensation,
our enthusiasm grew
because hydrogen seemed
like such
a wonderful atom to use.
It had everything going for it.
It had its light mass.
That means that
the atoms will condense
at a higher temperature
than other atoms would.
The atoms interact with
each other very, very weakly.
All the signals seem to be
pointing to the fact
that hydrogen was the atom
for getting
to Bose-Einstein condensation.
(narrator)
Kleppner's idea was
to cool the hydrogen atoms
by making use
of their magnetic poles.
He used a strong magnetic field
to create a cluster
of atoms in a cold trap.
Unfortunately, sometimes
one atom flipped another,
which triggered
a release of energy
that raised the temperature.
[sighs] It was
a frustrating time for us
because our methods
were so complicated
we were having a hard time
moving forwards.
(narrator)
Now others decided
to take up the challenge.
Two physicists from MIT
met in Boulder, Colorado
and came up with a different
approach to the problem.
Rather than focusing on
the lighter atoms
of the periodic table,
they hit upon
the idea of using
much heavier metallic atoms,
like rubidium and caesium.
But would using
these giants enable them
to reach closer
to absolute zero?
The idea in the field
in those days was that
the light things like hydrogen
and lithium would be easier,
and there are some good
reasons for thinking that.
But we had other ideas.
Yeah, sort of gut intuition
in some sense.
(narrator)
Their plan was to use
a laser beam to cool the atoms,
a technique that had already
been tried by physicists at MIT.
Lasers are usually associated
with making things hot,
but if they are tuned
to the same frequency as atoms
traveling at a particular speed,
lasers can cool them down.
When the stream of
light particles from the laser
hits the selected atoms
in the gas cloud,
they slow down
and become cold.
Laser cooling was a new tool
that had the potential
to reduce
the temperature of a gas
to within a few millionths
of a degree of absolute zero.
But Cornell and Weiman were not
the only ones excited
by this prospect.
A new scientist
had arrived at MIT.
(Wolfgang Ketterle)
It was in late '91 or early '92
that we had an idea,
an idea how a different
arrangement of laser beams
would be able to cool atoms
to higher density.
And it worked!
And this was
really a trigger point.
I will never forget the
excitement in those groups,
group meetings, when we
discussed what will be next,
because with higher density,
there are
many things you can do.
Could we now push
to Bose-Einstein condensation?
I see, well, lots
of cables and electronics...
(narrator)
All the resources of Ketterle's
lab were redirected
to make a condensate
in sodium atoms.
And right here, this
is an atomic beam oven.
What is wrapped in tinfoil
is a little vacuum chamber
where we heat up
metallic sodium,
so the metallic sodium
melts and evaporates,
and it's ultimately
the sodium vapor,
the sodium atoms, which we tried
to Bose-Einstein condense.
(narrator)
MIT, Boulder, and several other
labs were chasing the same goal.
It had echoes of the race
to produce liquid helium
almost a century earlier.
(Eric Cornell)
As I tell my students today,
anything worth doing
is worth doing quickly,
because science
moves on and...
we're all mortal
and you want to do things.
(narrator)
While MIT was installing
its sophisticated lasers,
Carl Weiman's approach was
"small is beautiful".
(Eric Cornell)
In some cases, he was
ripping open old fax machines
and taking out
the little chip inside
that made the laser and showed
that you could take these lasers
and put them into a home-built
piece of apparatus,
stabilize the laser,
and use them
to do spectroscopy
and laser cooling.
(Carl Weiman)
This is actually our first,
what's called
a "vapor cell optical trap."
You can see it's kind of
this old cruddy thing
pulled together glass where we
could send laser beams in
from all the different
directions
and have just a little bit of
the atoms we wanted to cool.
(narrator)
As well as bombarding
the atoms with lasers,
they also trapped them
in a strong magnetic field.
We would try this
sort of magnetic trap,
that sort of magnetic trap,
this sort of imaging,
that sort of imaging,
that sort of cooling.
All those things we could do
without building a whole
new chamber each time.
We tried literally
4 different magnetic traps
in 4 years
instead of having
a 3 or 4-year construction
project for each one.
(narrator)
By being fast and flexible,
the Boulder group hoped to beat
their old lab at MIT,
but MIT had its own plans.
(Wolfgang Ketterle)
There was a sense
of competition,
but it was what I would call
friendly competition.
I mean, can you imagine
2 athletes;
they are in
the same training camps,
they help each other, they even
give tips to each other,
but then when it comes
to the race,
everybody wants to be the first.
The rival groups
were both using
magnetic trapping and lasers
to cool their atoms,
but for the final push
towards absolute zero
to turn these atoms of gas
into the quantum state
Einstein had predicted,
they needed one more cooling
technique-- evaporative cooling.
It's just like with this coffee;
the steam coming off the coffee
is the hottest
of the coffee molecules
escaping and carrying away more
than their fair share of energy.
In the case of the atoms,
we keep the atoms in
a sort of magnetic bowl,
and we confine the atoms there.
They zoom around inside the
bowl, and then the hottest ones
have enough energy to roll up
the side of the bowl
and fall over the edge,
slop over the edge,
taking away with them much more
than their fair share of energy.
And the atoms that remain have
less and less energy,
which means they move
slower and slower
and start to cluster
near the bottom.
And as that happens,
we gradually lower the edges
of the magnetic trap
and always so there's just
a few atoms that can escape,
until finally
the remaining atoms cluster
near the bottle of the bowl,
huddle together,
they get colder and colder
and denser and denser
and eventually in this way,
evaporation forces
the Bose-Einstein
condensation to occur.
(narrator)
The race to produce
a Bose-Einstein condensate
was intensifying.
At every major meeting,
Eric Cornell and I gave talks
or talked to each other.
We were keenly aware
that we were
both working
towards the same goal.
(narrator)
In June 1995, the Boulder group
was working 'round the clock
knowing that MIT
and several other labs
were also poised to produce
the first condensate.
An official visit from a
government-funding agency
was the last thing they needed.
We didn't want to
close down the lab
or clean up our lab
or put up posters.
We wanted to
work very hard.
So the senior dignitaries
in the 3-piece suits and so on
came into the lab,
and we left the lights off,
and everyone
continued to work,
and I made them keep
their voices down.
And talked to them
rather in a hurried way
and then sort of
shuffled them out the door,
and they all had a slightly
puzzled look on their face
'cause it probably had never
happened to them before
in their history of being
a visiting committee,
that they were treated with
as little...little pomp.
And later, I actually met
one of the guys who said,
I suspected something
was up that day
because otherwise you never
would've dared to do that.
(narrator) June the 5th, 1995
turned out to be a big day
in the history of physics.
The Boulder group seemed to
have made what Einstein had
theorized 70 years before--
a Bose-Einstein condensate.
Our first reaction was wait, we
gotta be careful here, you know.
Let's think of all the different
knobs we can turn,
checks we can make and so on
to see if this really is
Bose-Einstein condensation.
(Eric Cornell)
A condensate is
sort of like a vampire.
If the sunlight even once
falls on it, it's dead,
and so it its realm
is the realm of the dark.
But we can take
pictures of them
because we strobe
the laser light really fast,
and even as the condensate's
dying, it casts a shadow,
and the shadow is
frozen in the film.
(narrator)
At a temperature of
170 billionth of a degree
above absolute zero,
Weiman and Cornell created
a pure Bose-Einstein condensate
in a gas cloud
of just 3000 atoms
of rubidium,
the first in the universe,
as far as we know.
One of the first things
you need to understand
about Bose-Einstein condensation
is how very, very cold it is.
Where we live,
at room temperature,
is far above absolute zero
in the scale.
Imagine that room temperature
is represented by London,
thousands of kilometers
from here.
Then on that scale, if we
imagine right here
where I'm standing in Boulder
is absolute zero,
the coldest possible
temperature,
then how close are we
to absolute zero?
If we think of London
as being room temperature
and right where I am
is absolute zero,
then Bose-Einstein
condensation occurs just
the thickness of this pencil
lead away from absolute zero.
(narrator) Within months of
the Boulder group's success,
Wolfgang Ketterle produced
an even larger condensate
from half a million sodium atoms
slowed down to a virtual
standstill,
causing their wave functions
to overlap
to produce an entirely new
state of matter.
At last quantum mechanics
was more than just
a theoretical construct.
It was something that could be
seen with the naked eye.
Cornell, Ketterle & Weiman
shared the Nobel Prize
for physics in 2001.
(Carl Weiman)
One of the things
Nobel Prize means
and the ceremony means is
that everybody remembers
Eric's the person
who forgot
to bow to the king!
There was a breakdown
of protocol on my part.
There was no excuse because
they actually drill us.
It's more like a--we have
a series of rehearsals
practicing how to bow to the
king, and I somehow managed
to bollocks it up at
the last possible moment.
And I thought maybe,
you know,
Carl who came after me would do
this, make the same mistake,
and then no one would figure it
out, but no, he was perfect.
(Wolfgang Ketterle)
I heard about the Nobel Prize
when I was
woken up by a telephone call,
which was at, I think,
5:30 in the morning.
So you wake up, you go
to the telephone,
and somebody tells you,
"Congratulations,
you have won the Nobel Prize."
You're still tired, your brain
is not fully functional,
but you realize this is big
and what you feel is,
you know, pride,
pride for MIT, your
collaborators, for yourself.
It's wonderful to see that
your work gets recognized
and acknowledged in this way.
(narrator)
Like any great adventure,
the pursuit of science offers
no guarantee of success.
But for the godfather
of ultra cold atoms,
persistence eventually paid off.
In 1998, after 20 years
of struggling
to obtain a condensate
in hydrogen,
Dan Kleppner finally succeeded.
For a few fleeting moments,
his dream came true.
(Daniel Kleppner)
Of course, we were delighted,
and I think everyone
was delighted
because we'd been working
on it for so long.
It's kind of embarrassing to
have this group,
which helped start the work
and was working away there,
fruitlessly, while everyone
was enjoying success.
When we got it,
everyone was happy.
(Wolfgang Ketterle)
To see that an effort,
which lasted for 20 years,
which took so much patience,
frustration and tenacity,
to see that succeed is just
emotional. It's liberating.
I will never forget
the standing ovation,
which Dan Kleppner received at
the Verena Summer School
when he announced Bose-Einstein
condensation in hydrogen.
Everybody just got up and gave--
it was
sort of like an opera where
everybody just cheered,
[with emotion] and people were
crying, because everybody
realized that they had finished
the race, but too late,
and it wasn't gonna work out,
but in some sense,
they had really stimulated
the whole field.
So it was a very, very moving,
very moving moment.
(narrator)
For the pioneers who had
realized Einstein's dream
and created condensates, it was
the end of an extraordinary
decade of physics.
Now, there was
a new challenge--
to work out
what to do with them.
At Harvard, a Danish scientist,
Lene Hau,
had the idea of using a
condensate to slow down light.
We all have this sense, you
know, light is something that--
nothing goes faster than light,
in vacuum,
and if somehow we could use
this system
to get light down to,
you know, to a human level,
I thought that was just
absolutely fascinating.
(narrator)
Lene Hau created a cigar-shaped
Bose-Einstein condensate
to carry out her experiment.
She fired a light pulse
into the cloud.
The speed of light is around
186,000 miles per second,
but when the pulse
hits the condensate,
it slows down
to the speed of a bicycle.
(Lene Hau)
So light pulse might start out
being 1 to 2 miles long
in free space,
it goes into our medium,
and since the front edge enters
first that will slow down.
The back end is still in free
space, that'll catch up,
and that'll create that
compression.
And it'll end up being
compressed
from 1 to 2 miles down
to 0.001 micron
or even smaller than that.
You could say well, gee,
it's easy to stop light
because I could just send
a laser beam into a wall
and I would stop it.
Well, the problem is,
you lose the information
because it turns into heat.
You can never get that
information back.
In our case, when we stop it,
the information is not lost
because that's stored
in the medium,
then we have time
to revive it,
the system has
all the information
to revive the light pulse,
and it can move on.
(narrator)
One day, ultra cold atoms
will probably be used
to store
and even process information.
Even now,
cold atoms are being
turned into prototype
quantum computers.
(Seth Lloyd)
As a quantum mechanic,
I engineer atoms.
To make a computer out of atoms,
you have to somehow get atoms
to register information
and then to process it.
Why build quantum computers?
Because they're cool, it's fun,
and we can do it. Right?
I mean, we actually can
take atoms
and if we ask them nicely,
they'll compute.
That's a lot of fun.
I mean, have you ever
talked to an atom recently and
had it talk back? It's great!
(narrator)
Unlike ordinary computers
where each decision is based
around a bit of information
and is either a zero or a one,
in the quantum world,
the rules change.
At first glance,
a quantum computer
looks almost exactly the same.
But quantum mechanics
is weird.
It's funky, okay?
It's weird.
(Peter Shor)
When you do quantum computing,
you want to make
this weirdness work for you.
So now let's look at our
quantum bit or Q bit.
The Q bit can not only be a zero
or a one, it can also both be...
A zero and one
(both) at the same time.
It's almost like a form
of parallel computation,
If you look at
the mini worlds
but in the parallel computer,
interpretation
of a quantum computer,
one processor does this,
one processor does that,
your quantum computer
so you have 2 processors
doing this and that.
is doing many,
In a quantum computer,
you have
many computations
only one processor doing
all at the same time.
this and that
at the same time.
[both laugh]
(narrator)
Today, computers are limited
in the amount of information
they can handle
by the heat
and number of the circuits.
Here, within a giant Dewar Flask
lies a prototype
quantum computer
surrounded by its supercooled,
superconducting magnet.
In the future, quantum computing
could be used to predict
incredibly complex
quantum interactions,
such as how a new drug acts
on faulty biochemistry.
Or to solve
complex encryption problems,
like decoding prime numbers
that are the key
to Internet security.
Already, supercooled quantum
devices are mapping
the magnetic activity
of the brain.
Often, the promised benefits
from a scientific breakthrough
take a long time to emerge.
Many predicted that
by this century,
energy saving superconducting
power lines
and maglev bullet trains
would be crisscrossing
the continents.
Perhaps as world energy supplies
decline, these technologies,
once seen as too costly,
will start to take off.
This weird quantum world is
part of a new frontier
opened up by the descent
towards absolute zero.
It's been a remarkable journey
for scientists
into unknown territories
far beyond
the narrow confines of earth.
On the Kelvin temperature scale,
which begins at absolute zero,
the temperature of the sun
is around 5000 Kelvin.
At 1000 Kelvin, metals melt.
At 300, we reach what we think
of as room temperature.
Air liquefies at 100 Kelvin,
hydrogen at 20,
helium at 4 Kelvin.
The deepest outer space is
3 degrees above absolute zero.
But the descent
doesn't stop there.
With ultra cold refrigerators,
the decimal point
shifts 3 places
to a few 1000ths of a degree,
and laser cooling takes it down
3 more places
to a millionth of a degree,
the temperature of
a Bose-Einstein condensate.
With magnetic cooling,
we shift 4 more decimal places
until we reach the coldest
recorded temperature
in the universe,
created at a lab in Helsinki,
100 pico Kelvin,
or a 10th of a billionth
of a degree above absolute zero.
So will it ever be
possible to go all the way,
to reach the Holy Grail of cold,
zero Kelvin?
(Seth Lloyd)
Getting to absolute zero
is tough. [laughs]
Nobody's actually been there
at absolute 0.000000...
with an infinite number 0s.
That last little
tiny bit of heat
becomes harder and harder
to get out, and in particular,
the time scales
for getting it out
get longer and longer
and longer
the smaller and smaller
the amounts of energy involved.
So eventually, if you're
talking about extracting
an amount of energy
that's sufficiently small,
it would indeed take the age
of the universe to do it.
Also, actually, you'd
need an apparatus
the size of the universe to do
it, but that's another story!
(narrator)
Absolute zero may be
unreachable,
but by exploring
further and further
towards this ultimate
destination of cold,
the most fundamental secrets
of matter have been revealed.
If our past was defined
by our mastery of heat,
perhaps our future lies in
the continuing conquest of cold.
Text : WTC-SWE