Original subtitles

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.

[ Engine revs ]

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?

[ Crying ]

Freeman: Space, time, life itself.

The secrets of the cosmos lie through the wormhole.

? Through the Wormhole 2x08 ? Can We Live Forever? Original Air Date on July 27, 2011

== sync, corrected by elderman ==

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?

[ Engine revving ]

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?

[ Engine revving ]

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 reason

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.

[ Gulp! ]

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...

[ Tires screech ]

...Hubs are like major intersections

where a constant flow of traffic passes through,

getting people from one place to another.

[ Bell clangs ]

These intersections are so essential --

if they become disrupted in any way, the whole city shuts down.

[ Sloop! ]

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?"

[ Electricity crackling ]

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're the 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...

[ Chord plays ]

...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.

== sync, corrected by elderman ==