Freeman: The end of life.
It's a reality that terrifies us and motivates us.
Now cutting-edge science embarks on a bold mission
to extend human life.
Some think the answer lies in biology.
Some believe it might be in our brains.
And others claim that immortality would mean
the end of humanity.
Will death remain inevitable?
Or can we live forever?
Freeman: Space, time, life itself.
The secrets of the cosmos lie Through the Wormhole.
The sands of time run swiftly,
a reminder that life is fleeting;
death is a humbling reality.
But what if life had no end?
In just the past 200 years,
the average life-span has doubled
from about 40 to almost 80 years.
Breakthroughs in biology and physics
could soon bring immortality within our grasp.
For better or worse, many of you watching me right now
may live to see the day
when aging and death itself are relics of a distant past.
I remember rummaging through my grandmother's trunk once,
happening upon objects that had been stored away for years.
Everything was faded, curled, rusted.
I couldn't help but wonder,
when would the same decay happen to me?
Michio Kaku,
a theoretical physicist at City College of New York,
is fascinated with the big questions in science,
like whether the laws of physics
require that all living things die.
One of the iron laws of physics
is the Second Law of Thermodynamics,
which says that everything rusts,
everything decays, falls apart.
We're all made out of atoms, and these atoms, in turn,
obey the Second Law of Thermodynamics.
Freeman: Anything and everything in the Universe
has the tendency to go from order to disorder.
And once the damage is done,
it's extremely difficult to reverse things and un-mix them.
It's a process known as entropy.
If I mix coffee,
I realize that when I put cream into coffee, I increase entropy.
I increase disorder.
In fact, to see this milk jump out and reform in this cup
is such a preposterous event
that you would have to wait longer
than the lifetime of the Universe to see it happen.
Freeman: The Second Law of Thermodynamics is an unremitting force.
Nothing is immune to the power of entropy,
not even the cells in our body.
Kaku: And that's why we age.
In fact, that's why we die.
But it turns out that there is a loophole to the law of entropy.
There is a way to restore order from disorder.
Kaku: Imagine that each one represents an atom.
Now, if I apply the Second Law of Thermodynamics,
it means that entropy increases. It mixes. Chaos reigns.
Watch this.
Freeman: The candy on the tray starts off organized and color-coded.
But if the tray begins to vibrate,
the Second Law takes over.
Kaku: Even though this is entropy in action,
I can reverse entropy by adding energy from the outside.
But the price is, I have to constantly be on alert,
constantly add energy from the outside.
I mean, this is hard work.
Freeman: With energy and concentration,
Michio can step in and stop the chaos.
But reversing entropy in a tray of vibrating candy
is far less complicated than reversing entropy in our bodies.
Where would we even begin?
Valter Longo is searching for the answer.
He is a professor of gerontology
at the University of Southern California.
He knows that many things live fast and die young,
and he believes the road to reversing entropy in the body
starts where things get the hottest - in the engine.
Longo: In the engine, the gasoline gets oxidized,
and that's a combustion process,
and this provides energy to the car.
But because of the combustion,
the engine itself can become damaged,
and eventually, you have to rebuild the engine.
Freeman: Every cell in our bodies
have tiny engines called mitochondria.
Mitochondria are double-membraned structures
whose job is to provide energy.
But when these powerhouses wear down,
our body begins to decay and age.
And so, you can imagine in the cells, instead,
you have hundreds of these mitochondria,
these little engines.
And these hundreds of engines provide the energy locally
to every single cell in our body.
Freeman: But Valter has found a way
to reverse this deterioration process
and rejuvenate mitochondria in one tiny organism.
He has extended the life of baker's yeast -
the kind you use to make bread and beer - to 10 weeks.
That's 10 times the yeast's normal life-span of 6 days.
It may not sound like a long time,
but it's equivalent to 800 human years.
The yeast's longevity occurred
when two genes, R.A.S.2 and S.C.H.9,
were removed from its DNA.
Longo: So these pathways that we've identified in yeast,
in addition to promoting aging, they also promote DNA damage
and the damage
of a variety of different systems within the cells.
Freeman: Valter wondered if this fountain of youth for yeast
might apply to more complex life-forms.
And so he began looking for the equivalent genes
in a much larger organism -
mice.
When he knocked out those two genes,
these mice doubled their life expectancy.
Longo: This is very encouraging
because if you look at the similarities
between a mouse and a human,
we are over 90% identical in many ways.
A mouse lives for 2 years, and people live for 100 years.
So, you can see,
with just a small modification of the genome,
you can go from 2 years to 100 years.
There's no law of physics
that prevents us from finding the secret of longevity,
the secret, perhaps, even of immortality.
If you take, for example, the genome of millions of old people
and the genome of millions of young people -
which we will do in the coming years - and subtract,
you will then find the genes where aging is concentrated.
Already, we've identified over 60 genes
involved in the aging process.
Longo: Now, the question is,
how do you reprogram a human that lives 100 years
to be now a 2,000 - or 3,000-year-old person?
Freeman: Valter's mission to keep our engines running forever
has just begun, and he's in it for the long haul.
Suppose we do find a way
to keep our engines running for hundreds of years or more.
We would all be very old for a very long time.
But this scientist
is digging for ways to keep us not just eternally alive...
but eternally young.
Take our current life-span
and stretch it 5 or even 10 times longer.
The joys of our youth would endure like an endless summer.
But imagine suffering decade after decade with fragile bones,
failing eyesight, and an ever-more-feeble mind.
If we want to become immortal, we can't just extend life.
We need to discover how to keep our bodies eternally youthful.
Aubrey De Grey thinks of himself as a modern-day Methuselah.
He has dedicated his career to fighting aging.
Aubrey believes that many people who are born today
could live to be 1,000 years old
and remain physically young for most of that time.
The key is a matter of good biological housekeeping -
taking the trash out of ourselves.
So, what happens, indeed,
is that certain types of material in the body
just accumulate junk.
Certain types of junk accumulate inside cells and between cells
and stuff that we would not think of as junk, like DNA,
accumulates randomness, which is a type of junk.
Freeman: Cells have the important job
of constantly breaking down waste,
and they're mostly pretty good at it.
But sometimes a cell
comes across things that are so weird...
none of this degradation machinery works on them.
That's when the junk gets re-routed
to what's called the lysosome,
a vessel that houses
the most powerful degradation machinery in the cell.
And if the garbage can't be broken down,
it stays there forever.
Aubrey believes that the accumulation of garbage
in the lysosomal storage unit is what causes aging.
And he wants to free our bodies of these buildups.
He realized the most logical way
was to take a close look at waste itself.
And he wondered, "In nature, what likes to eat junk?"
Longo: We're working on an idea
that we might be able to find other species,
especially bacteria, that are able to break down
the substances that accumulate in the human body.
Freeman: Aubrey's hunt for the fountain of youth
led him to a final resting place - graveyards.
Since graveyards are riddled
with the waste of decomposing bodies,
he suspected he might find microbes
who live to feast on death.
De Grey: And if we can find the genes and enzymes that they are using
to actually perform that function,
then we might be able to put those genes and enzymes
into our own cells
so that our own cells can break stuff down
that they could not naturally break down.
Freeman: The secret to longevity might be 6 feet under.
Aubrey and his team are still digging for the right microbe
that will work in mammalian cells.
And when they find it,
he believes we will all live like 25-year-olds forever.
De Grey: I think that we have maybe a 50/50 chance
in the next 25 years or so
of developing what I think of as the first generation
of bona fide rejuvenation biotechnology.
In other words,
technologies that are sufficiently comprehensive
that we can give them to middle-aged people,
people 60 or 70 or so, and fix them up well enough
that they don't become biologically 60 or 70 again
until 30 years later or something like that.
Freeman: Aubrey is looking for the magic bullet that will fight aging,
but synthetic biologist Chris Voigt
is looking to build an entire army
out of various parts from all over nature.
Voigt: All right. Let's give this a shot.
One of the things we're often trying to do
in synthetic biology is create new functions
out of parts that already exist in nature for other reasons.
So we're often having to go out and grab those components
from different organisms and put them together.
Freeman: Chris searches for microorganisms
throughout biology to find the right parts.
And they end up at his lab
at the University of California, San Francisco,
where biology meets mechanics.
Voigt: When you look at being able to fight disease,
whether it's identifying malignant cells
and killing them,
we're trying to go through the garbage of all the functions
that are out in the natural world
and identify those that are useful to us
in trying to be able to identify
a correct disease state in the body.
Freeman: To build a bio robot that can detect its surroundings,
Chris and his team needed to find an organism with a sensor.
And they found it... in pond scum...
where they discovered that algae are equipped with light sensors.
Voigt: We took a bacterium that normally lives in your gut -
so it's not used to the Sun shining -
and we put in a light sensor out of an algae.
Freeman: Inside Chris' bacterial darkroom,
colonies of bacteria
that are now implanted with algae light sensors
are able to take photographs of slide-projected images.
Freeman: It might look like bacterial art,
but this is the first big step
toward creating programmable biological robots
that will keep our bodies healthy forever.
Voigt: There are bacteria all throughout our bodies,
and we can reprogram those bacteria
in order to be able to implement therapeutic effects
for just about any disease that you can imagine.
The possibilities are limitless.
Freeman: Chris' photographic bacteria
are able to turn themselves on and off
like the flip of a switch.
But the question is,
can Chris figure out how to program and control that switch?
We'd like to see the programming of cells
be the same as programming a computer
or designing an electronic chip,
where, as programmers, we would write out
the exact function that we'd want the cells to do.
And then that would be automatically compiled
into a DNA sequence
in the same way that a computer program
gets compiled, ultimately, into ones and zeroes.
That's the dream.
Freeman: Bio robots may one day roam our blood streams,
police our organs, and respond to our internal 911 calls,
keeping us free from the threat of disease.
Chris Voigt's and Aubrey De Grey's research
to keep our bodies healthy for eternity
is still in the beginning stages.
But what does this mean for us mere mortals
who will never live to see the day
when immortality is within reach?
There is one chilling possibility
that will give us all a chance to hang on, even after we die.
We're all genetically programmed
to lust for life and to flee from death.
Eventually, we will discover the secret of immortality,
but we're not there yet.
To cheat death right now, we need to put aging on ice
and be ready to grasp eternal life
long after life abandons us.
Greg Fahy is a cryobiologist.
The goal of his team at Biotech Outfit 21st Century Medicine
is to freeze human organs and tissues
so that they can be revived, undamaged, centuries from now.
Fahy: Cryopreservation is the preservation of living systems
at very low temperatures.
We usually are referring to temperatures that are low enough
that you can store the system as long as you wish
before you use it again.
Cryopreservation is essential
to get a cell or a tissue, an organ,
from one place in time to another place in time
without allowing that system to change in the process.
Freeman: Scientists have been trying
to preserve whole organs for decades.
But it's a lot harder than throwing food in the freezer.
When biological material freezes, ice crystals form,
which push the cells out of their normal position.
When you thaw the organ, it may look okay from the outside,
but on the inside, it's damaged beyond repair.
The biggest problem, we think, is really mechanical.
It's the formation of ice between cells.
If the cells are dislodged from their normal locations,
then you can destroy
the function of that structure as a whole
even if the cells survive.
Freeman: Greg and his team decided to focus their efforts
on preventing bodily fluids from freezing
and eventually developed a way
to turn those fluids into a form of biological glass -
a technique he calls vitrification.
Fahy: Vitrification is the formation of a glass.
So if you take water and you mix it with various chemicals
in high-enough concentrations of chemical
and then cool it down to low temperatures,
the system will never freeze no matter how low you go.
Freeman: To test whether
vitrification actually preserves the function of whole organs,
Greg's team vitrified a rabbit kidney.
Fahy: This is the kidney profusion lab.
What John is doing in the background
is delivering... through the vascular system of the kidney
so the kidney becomes unfreezable.
The kidney is sitting in a special chamber.
The chamber is temperature-conditioned
to minimize toxicity.
And at the end of the process,
the kidney's taken out and is transplanted.
Freeman: This kidney,
even though it has been stored at minus-22 degrees Celsius,
works just as well as a normal kidney.
It's proof
that Greg's vitrification technique actually works
and might be the key
to preserving human organs far into the future.
So if you cool to below that glass-transition temperature,
our calculations indicate you can store a system
for tens of thousands of years.
Freeman: Imagine being able to put your body on ice
and then being revived 10,000 years from now.
You could wake up and find yourself
in an age when science has made immortality possible.
Greg Fahy may be just a few years
from giving a few select people a shot at eternal life.
But that can only happen
if cryopreservation works on an entire human body,
not just simple organs like the kidney or the bladder,
but on the most complex organ of all - the brain.
Fahy: This is the brain-slice vitrification lab.
The setup shows a hippocampal slice -
the part of the brain that's associated with learning and memory -
in a little dish, essentially.
On the right side, we have a stimulating electrode coming in,
piercing the slice.
On the left side, we have a recording electrode.
Freeman: This brain slice has been vitrified.
If it's still functional,
when a pulse of electricity is fired into it,
it should fire a signal back.
To Greg and his team's surprise, it does.
Electrical activity actually sparks up in this brain tissue.
And the electrical response
is every bit as strong as it was in its original state -
the recovery of the brain slice complete.
Preserving a slice of the brain
is a crucial first step toward preserving the whole thing.
It's an ambitious project that Greg is already working on.
We have found that it's fairly easy to vitrify the brain,
that all of the structure seems to be preserved.
But I have to say that so far,
our techniques are not up to the level
that we would like for that kind of speculative idea.
But I couldn't say that you couldn't make up
for whatever deficiencies
that we have in our preservation technique today
using some unknown future technology.
I can't rule that out as a possibility.
One day, centuries after we say goodbye to our loved ones,
our frozen bodies could be reanimated,
and we'll walk the Earth again.
But there could be a better route to immortality,
one that would change
the very nature of what it means to be human.
Imagine if no one ever died.
Where would we all live?
Our planet is already crowded enough.
But maybe there is a way to live forever
without all this excess baggage.
Poets say the essence of us is here,
but I know what really makes me me is all up here.
So if I want to endure for eternity,
perhaps that's all I need to hang on to.
What if we could find a way to upload our brains,
to digitize the very essence of ourselves?
Our minds could go on living long after our flesh has died.
But to make that happen,
we need to understand the brain's architecture
and figure out what truly makes us who we are.
Olaf Sporns is a neuroscientist at Indiana University.
He is attempting to unscramble the brain's tangled web.
Sporns: The brain is like a big city.
Cities are examples of complex systems -
thousands of inhabitants and their social interactions,
their flow of materials.
The brain is like that - millions of neurons,
interactions between these neurons.
In a sense, your brain is like a city of the mind.
Freeman: The human brain
is one of the most complex systems in the Universe.
If you stretched out all of its electrical wiring,
it would extend from the Earth to the Moon.
Figuring out how we get from cells and wires
to thoughts and memories
is one of the greatest challenges known to science.
Even though we've been studying the human brain,
really, for decades, perhaps centuries,
we still don't have a complete map of how it's connected.
Freeman: But Olaf is taking on this challenge.
His goal is to chart every single neuron and synapse
and create a complete map of the brain, called the connectome.
Sporns: It's a comprehensive set of connections
that will allow us for the first time
to understand in more detail
how brain regions are connected to each other.
Freeman: Olaf is creating the connectome
using a leading-edge technique called diffusion imaging.
It reveals the brain's long-distance connections
by tracking water molecules along the neural highways.
And what emerges is a detailed map
of the central core of brain-cell connections.
Olaf thinks this is the area where our personality resides.
Sporns: As we've been discovering recently,
some brain regions are more connected than others.
Some are more essential, perhaps,
for the functioning of the brain as a whole.
Those regions, we call hubs.
Freeman: If the brain is like a city...
...hubs are like major intersections
where a constant flow of traffic passes through,
getting people from one place to another.
These intersections are so essential -
if they become disrupted in any way, the whole city shuts down.
By their nature, hubs are focal points of information traffic.
Information converges on these regions,
and it is that ebb and flow of information
and the magnitude of the information flow
that really sets these hubs apart
from other regions of the brain.
Freeman: Olaf is getting closer
to figuring out where consciousness resides.
Searching for the origins of consciousness
is the holy grail of neuroscience.
Only when this mystery is solved can we replicate the human brain
and take consciousness from a person
and transfer it to a machine as a way to live for eternity.
And Olaf believes he has discovered a hub
that might solve this mystery - the medial parietal cortex.
It's located between the brain's two hemispheres.
Olaf suspects it might house the essence of who we are.
Sporns: A lot of wires from the brain converge on that region.
There are many lines of evidence
that point to that part of the brain
being really central and really important -
perhaps even for awareness and consciousness.
Freeman: Olaf believes
he may have solved the secrets of consciousness,
but there is much more work to be done before he can be sure.
Sporns: I think we're getting closer to answering this
question.
And as we identify which parts of the brain are critical
in bringing about that particular functionality,
that gets us closer to answering the question,
"What is consciousness?"
And also "Where are the critical components of the brain
that contribute to it?"
Freeman: Neuroscience has taken enormous steps
towards mapping the brain
and solving the riddle of consciousness.
But will we ever be able to capture
the trillions of synapses, billions of neurons,
and download ourselves onto a machine?
Just imagine all the things that happen in the real world -
the conversation we are having now,
me producing speech sounds and gestures,
our brain's interacting in this embodied manner.
That could not happen in a computer,
and yet, it is somehow
the essence of what life is all about.
So I'm skeptical about that.
Freeman: The brain might be far too complex to immortalize,
but maybe there's a simpler path to eternal life -
not for you...
but for immortal beings that we create from scratch.
Life on this planet
has had 4 billion years to evolve.
We are the latest in a long line of species.
We hope we can last.
But our quest for immortality could end in disaster
because the first eternal beings may not be human.
And they might just make us extinct.
Complex life began from a few simple laws.
The same might be true for artificial life.
If humans discover those laws, there is a chance
we could create living things that live forever.
Oxford physicist Vlatko Vedral is trying to understand
how intelligence might emerge from a system
that operates on just a few basic ground rules.
Vedral: So, this is chess.
It's a very complex game,
and yet it's governed by a few very simple rules.
You really have only 16 pieces on each side,
and each piece can do one of two things.
And you can say the same thing about life.
Even though you are talking
about one or two very simple rules,
you still get this multitude
of different possible behaviors in the Universe.
Freeman: In 1970, a mathematician named John Conway
ran with this idea
and attempted to create artificial life-forms
spontaneously using a computer program.
He called it "The Game of Life."
The game simulates the growth of artificial life,
using a two-dimensional grid
and simple cells that are either dead or alive.
Whether the cells live or die is governed by a few basic rules.
So, we have here in front of us a large cell block,
and we can see this one central cell, which is on.
And we can see that it has only one neighbor to its left.
The cell just switches off, which means that it dies.
And it dies of loneliness
because it has too few neighbors.
Well, now we've got a central cell, which is on,
but it has five neighbors.
It dies because of overcrowding, overpopulation.
It doesn't like it, either.
In the third example, a cell with only two neighbors -
the cell just keeps on living.
It can even move around in this environment,
and it can reproduce.
So this is a good example where the population is just right
for the cell to keep on living.
Freeman: Given enough time, increasingly complex patterns
emerge from this simple set of rules.
Some even take on the appearance of living organisms.
Vedral: John Conway tried to make the same point regarding life -
that it looks very complicated to us.
And, indeed, it looks like a miracle
that there is life around us,
but, in fact, he constructed a game
which consists of two or three, again, very simple rules,
and it gives rise to some very complicated patterns.
Freeman: How complex do these patterns need to be
before they become something alive, intelligent, or immortal?
Vlatko thinks the human brain is a good yardstick
and has calculated its processing power.
Vedral: The brain is currently still much more powerful
than the existing computers.
So the existing computers can do something like, you know,
10 to the power of 12 beats per second,
whereas our brain is still probably something
like a million times faster than that.
So you need 1 million laptops
to simulate just a single human brain.
Freeman: Today's computers are nowhere near powerful enough
to house artificial intelligent life.
Vlatko believes the answer might be to use
a completely different type of computer -
the quantum computer.
Quantum computer
is basically the future technology of computation.
It's a computer that's so fast, in principle,
that no current computer can compete with it.
Freeman: In place of transistors,
quantum devices compute with individual atoms.
And instead of sorting piles of ones and zeroes
to give yes-and-no answers,
the atoms in quantum computers
can be ones, zeroes, and everything in between,
existing as a computational maybe.
The quantum computer really utilizes
the quantum effect known as the super position,
which means being
in many different states at the same time.
Freeman: This ability to handle a multiplicity of states
allows quantum computers
to juggle many overlapping problems at once,
just the way our brains do.
The analogy would be if I played a chord for you...
...then you would get
many different modes played at the same time,
which would really correspond
to many states being out there simultaneously
all in one location
and the full power of quantum computation,
which is actually unlimited, in some sense,
if you start to store
all the values in between the zero and the one.
So then you really reach a stage where you can encode much more
and the capacity really has no limits in that sense.
Freeman: There might be a time
when humans forego their own dream of immortality
and create eternal artificial life.
And if they do,
how would artificial and biological life get along?
Some people think that very soon
computers will be smarter than us and they'll put us in zoos.
They'll put us behind bars and throw peanuts at us
and make us dance behind bars
just like we make bears dance in zoos today.
But at the present time,
none of these technologies are ready for prime time.
We simply don't have an operating quantum computer.
The world's record for a quantum computer calculation is -
ta-da -
3 times 5 is 15.
We sometimes forget that computers and robots,
no matter how advanced they are, are adding machines.
But that doesn't mean
they have creativity, imagination, initiative.
It doesn't mean they understand human values.
It doesn't mean that they can make leaps of logic like we can.
In other words, we have a long ways to go
before we can begin to approximate
the real thinking process that takes place in a human being.
Freeman: We're safe from becoming slaves to quantum intelligence...
for the time being.
But this physicist envisions a different fate for mankind,
one where the lines between artificial and biological life
will blur
and immortality will become reality,
not just for the living...
but also for the dead.
We're taught to think of science and religion
as separate truths.
Albert Einstein didn't believe that.
He said, "Science without religion is lame.
Religion without science is blind."
The secret to achieving immortality
could require the fusion of humanity and God
into an everlasting cosmic computer.
Few people think further into the future than Frank Tipler,
a mathematical physicist
at Tulane University in New Orleans.
Frank predicts that, at some point in our evolution,
something truly remarkable will happen.
Humanity, the Universe, and God will unite -
a moment he calls the omega point.
Tipler: The omega point is the very end of the Universe.
In the process, mankind, or, more precisely, our descendants,
will expand out from this planet
and ultimately engulf the entire Universe.
As our descendants are moving into this final state,
their knowledge and their power and their computer capacity
is increasing without limit.
The laws of physics
allow a process that will convert matter -
stones of this graveyard, for instance - into pure energy.
That will be the ultimate energy source,
which our descendants will use and gain control of it.
Freeman: At the omega point, Frank argues,
our descendants will be capable of doing anything.
And with infinite power, they will create a cosmic computer
and reconstruct in a simulation
everything that has ever happened
in the history of the Universe.
Now, from the point of view of the beings in the far future,
we will be their alternate ancestor as rational beings
so they will be interested in what we were, what we were like.
As a consequence, every man, woman, and child
will be brought back into existence.
It will be just like you are brought back with your body
into a reconstructed Earth just like we now live on.
It will be different in one crucial respect.
We will be resurrected,
but we will never have to go through death again.
Freeman: Frank claims the laws of physics
not only permit this type of immortality -
they actually require it to happen.
Tipler: Second Law of Thermodynamics says
the complexity of the Universe at the most fundamental level
is increasing without limit.
I conclude
that the validity of the Second Law of Thermodynamics,
throughout all of time,
actually requires life
to come into existence to gain control of the Universe.
Freeman: Whether immortality comes in billions of years
or whether it comes this century,
the conquest of death will transform our civilization -
the way we live, the way we work, the way we love.
Maybe the question is not "Can we live forever?"
But "Should we?"
Alexander Rose
is the executive director of the Long Now Foundation,
an organization whose main focus
is the building of an unusual timepiece.
It's called the Clock of the Long Now,
and it's designed to tick for 10,000 years.
Rose: We built the 10,000-year clock
to give people a different perspective
of the really long term.
If you believe that medical science or other things
are going to increase human longevity,
then the way that you would approach the world
would be very, very differently -
just the same way that if we're designing a 10,000-year clock
instead of a clock that just has to last for 10 years,
we have approached this design problem very differently.
And we have to be responsible over those next 10,000 years
for our clock.
Freeman: 10,000 years in the past,
we were still living in the stone age.
Flash forward the same period,
and our civilization and technology
will be unrecognizable.
We realize in designing a 10,000-year clock
that the most durable design is likely the simplest.
Freeman: The Clock of the Long Now will be all mechanical.
Power in the clock will come from the force of gravity.
A weight-driven system will turn a threaded bar.
And the clock will keep time
in both the short term, with the pendulum,
and in the long term, through a solar synchronizer.
This device may or may not last for 10 millennia,
but that's not really Alexander's point.
He wants to make us imagine what we will be like
10,000 years from now.
Rose: As soon as you see that 10,000-year clock
and you visit it, the conversations that you have
around whether or not humans will be there,
the shapes of the hands of the people that might wind it -
"Are they gonna be the same as ours?"
"Are they gonna be different?"
Those kind of conversations immediately allow you
to take responsibility for that kind of time span,
and that's the hope with this clock.
Freeman: 10,000 years from now, human beings may be immortal.
Even if they're not,
their life-spans will surely be vastly longer than ours.
But it won't be just our bodies that will change.
What it means to be human will be different.
If you think about all the human values,
quite a lot of them come
from the fact that we know that life is finite.
If you think, "How do I feel towards that person?"
The fact that you know
that the person is not gonna be there one day
probably makes your emotions far stronger in some sense
than other ways they would be.
So this could all change, and maybe some of these things
would even disappear from the human race
if we simply knew we could live forever.
Rose: What happens to marriage and relationships
if our life-spans grow to 1,000 years or more?
Right now,
half of us get divorced just in our short lifetimes.
But if we lived for 1,000 years,
who knows how many times you might get married?
I don't think that I would be able to live forever.
I think my wife would kill me first.
Freeman: Whether we like it or not,
more and more scientists believe we will one day live
in a world without age, disease, and death...
that we'll revel in the joys and wonders of endless life
and that we'll just have to learn to cope
with the consequences of living forever.
Mythology says that the gods envy our mortality.
Our mortality
is what makes life precious and something to be savored.
Driven by the pressure of time to achieve greatness,
it may be our mortality that gives us our humanity.
But as long as we are mortal,
we'll never stop dreaming of life everlasting.
That, too, is what makes us human.