0:00

This is a love letter to humanity.

0:03

My name is Josh Clark, and for the

0:05

last few years I've been thinking

0:08

a lot about how the world might

0:10

end, and over the course of that

0:12

time, I've come to seriously

0:14

believe that in a hundred or

0:17

two years from now, there's a

0:19

really good chance that we humans

0:21

won't be around any longer, that

0:23

we will have vanished forever from

0:26

the universe, and that it

0:28

may be us who brings about

0:30

our own demise. This

0:33

series is about the very real

0:35

ways that that could happen. It's

0:39

meant to open your eyes, hopefully

0:41

get you to take these ideas seriously

0:43

too, and ideally get

0:45

you to take action. But

0:48

just as much, I hope by

0:50

pointing out just how close we are

0:52

to the brink of disaster, you

0:54

come to feel the way that I have about

0:57

your fellow humans and humanity

0:59

as a whole. That we are flawed

1:02

and ugly and brutal, for

1:04

sure, but that we are worth

1:06

fighting to save, even from

1:09

ourselves. That the beauty

1:11

and the love that humans are capable of creating

1:14

is greater than the worst of our faults.

1:17

That nothing we've done is worth

1:19

letting our entire species come

1:22

to an untimely, impermanent end.

1:25

It's a bizarre thing to say, but

1:27

I found it's worth saying. Humans

1:30

don't deserve to go extinct.

1:34

This series is about existential

1:36

risks. We're not used to this

1:39

kind of risk, nor are we really

1:41

equipped to deal with them. I'll

1:43

tell you a lot more about them as

1:45

the series goes on, but while you listen,

1:48

try to keep in mind that no

1:50

horrible catastrophe, no world

1:52

war, no epidemic that's ever

1:55

come before, nothing we've ever

1:57

been through has prepared us to

2:00

take on existential risks. We

2:02

have no frame of reference for

2:04

them, because the destruction they can

2:06

bring is unprecedented in

2:08

the history of humanity. Yet,

2:11

and what maybe the weirdest turn of events

2:14

in the history of our species, A

2:16

whole crop of these new existential

2:18

threats are suddenly looming in

2:21

our near future. Each

2:23

one of them could bring about the sudden

2:26

and permanent end of the human

2:28

race. This would

2:30

be a particularly tragic thing. We

2:33

humans have only just begun to live.

2:36

Human civilization has been around for about

2:38

ten thousand years. Think about

2:40

what we've accomplished in that relatively

2:42

short time. Now, think

2:45

about what it might be like to be a human

2:47

after civilization has been around for a million

2:49

years or a billion. So

2:52

not only are the lives of those of us around

2:54

today on the line, but we

2:56

have to remember the lives of all the humans

2:59

to come are as well, and

3:02

the stakes for us avoiding extinction in

3:04

the next century might be even higher

3:06

than that. As we'll see in this episode,

3:09

we humans may be the only intelligent

3:11

life in the entire universe. If

3:14

we die, so too does

3:16

all the things that make us human, All

3:19

of the love and compassion, all of

3:21

the inventiveness and curiosity,

3:23

all of it perishes with us, not just here

3:25

on Earth, but in the universe

3:27

as a whole. It's

3:29

staggering to think, but the responsibility

3:32

for our own lives, for the future

3:34

of the human race, and for intelligent

3:37

life in the universe appears

3:39

to suddenly rest solely in

3:41

the hands of those of us alive today. It

3:45

would probably be good to know if we're alone

3:47

or not, just for the sake of knowing what's on

3:49

the line if we go extinct, So

3:51

let's start there. As

3:54

it turns out, you should know an

3:56

alien by now, so should

3:59

I. By this point in human

4:01

history, everyone you and I know should

4:03

know an alien. We should know

4:05

them from work, from your kids school.

4:08

They should be our neighbors. Earth

4:10

should be a melting pot of not just human

4:13

cultures, but extraterrestrial

4:15

ones too. At the very

4:17

least, we should be certain by now that there

4:19

are aliens out there, just

4:21

as sure as we know that there are people living in

4:23

France and Denmark. We should know that there are

4:25

aliens on proximous Centauri B or

4:28

trappist One F. And

4:30

yet we don't, and

4:32

you and I don't know any aliens, which

4:35

is actually very, very weird.

4:39

The reason why it's weird is that the universe

4:41

we live in is extremely old. It's

4:44

nearly thirteen and a half billion years

4:46

old, and our galaxy, the Milky

4:48

Way, is extremely vast from

4:51

the perspective of us humans. It

4:53

takes a beam of light a hundred thousand years

4:55

to cross it. And within our very

4:58

old and very immense galaxy, there

5:00

are a lot of stars, between

5:02

two hundred to three hundred billion

5:05

of them three hundred

5:07

thousand million stars.

5:10

Working from the premise that our own stars,

5:12

light and heat helped raise life here

5:14

on Earth, one would think that somewhere

5:17

among those three hundred thousand million

5:19

stars out there, the same thing would

5:21

have happened. It happened again and

5:24

again. By all rights, even

5:26

with just a slight fraction of those stars

5:28

growing life on a planet in orbit around

5:31

it, our galaxy should be teeming

5:33

with life like mold on a slice

5:35

of bread. There's certainly

5:37

been plenty of time for it to happen. Here

5:39

on Earth, life arose within the last

5:41

three and a half billion years and managed

5:44

to evolve from little strands of proteins

5:47

into us, sentient human beings

5:49

who have come to wonder if the same thing has happened

5:51

elsewhere too. Since

5:54

the galaxy is nearly four times older than

5:56

the time it took for intelligent life to emerge

5:58

here on Earth, it's had ample time

6:00

to emerge elsewhere in our galaxy too. So

6:03

what we've got is something of a mystery on our

6:05

hands. The universe is by far

6:07

old enough and definitely large enough

6:10

to have produced intelligent life over

6:12

and over and over again, and

6:15

yet we have not one iota

6:17

of evidence that we are anything

6:20

but utterly alone in the Milky Way. It's

6:23

become increasingly clear that when

6:25

we look out at the night sky, there's

6:27

nothing looking back at us. This

6:31

is the basis of what's come to be called the

6:33

Fermi paradox, and it begins,

6:36

like so many great strange things. Over

6:38

lunch in

6:45

the summer of nineteen fifty four physicists

6:47

ambled over to the Fuller Lodge, an

6:50

old two story boarding house made of human

6:52

logs with a big, hulking stackstone

6:54

fireplace that you could practically stand up in.

6:57

The Fuller Lodge had been converted into a mess

7:00

all for the people working on the Manhattan

7:02

Project at Los Alamos, New Mexico.

7:05

Taking a break from refining the most destructive

7:07

weapon the world has ever known into an

7:09

even more destructive one, these

7:11

four physicists got into chatting about

7:14

the UFO fever that had recently gripped

7:16

America. They dismissed

7:18

the idea that reports of UFOs were in

7:20

fact alien in origin, but they didn't

7:22

dismiss the idea that it was possible

7:25

life could exist elsewhere in the universe. It

7:28

was likely that it did, they concluded.

7:31

After the group had already moved on to other topics,

7:33

one of them, Enrico Fermi, abruptly

7:36

returned the conversation back to aliens.

7:38

Where is everybody? He asked, or perhaps,

7:41

but have you ever wondered where everybody is. The

7:44

precise words were lost over time, but

7:47

Fermie's three lunch companions all recalled

7:49

that they knew just what he meant, and

7:51

they grasped the implications as well. There

7:54

should be life all over our galaxy,

7:56

and yet there appears to be only us. Fairmi

8:00

never formally explored his question, but

8:02

it's understandable why it came to be named after

8:04

him. As physicists go, Faremi

8:07

was no slouch. He presided

8:09

over the first controlled nuclear reaction created

8:12

in a uranium pile of his design, constructed

8:15

on a squash court beneath the football field

8:17

at the University of Chicago. He

8:19

calculated formula that helped answer the shape

8:22

of matter on the quantum level, and a family

8:24

of quantum particles are named after him Fairmians,

8:27

and of course he helped build the bomb.

8:30

But more than Fairmi, it was an American

8:33

astronomer named Michael Hart who was

8:35

really responsible for the Fermi paradox.

8:38

In the mid seventies, Heart wrote a paper

8:40

called the Explanation for the Absence

8:42

of Extraterrestrials on Earth. He

8:45

summarized and organized the arguments against

8:47

the paradox, which come in a rainbow

8:49

of colors with only a couple of shapes,

8:52

and Heart ultimately concluded this because

8:55

life should reasonably have emerged and

8:57

be known to us by now. The fact

9:00

that it hasn't solves the family paradox.

9:03

The answer is that we are alone. Mystery

9:05

solved. Michael

9:08

Heart's paper struck a blow in particular

9:10

to the group most diametrically opposed

9:13

to his conclusions. City

9:15

researchers set the

9:17

search for extraterrestrial intelligence

9:19

is an offshoot of astronomy and astrobiology,

9:23

and back in the early sixties, astrobiology

9:25

hit the scientific scene like a bomb. It

9:28

was an exciting new discipline that treated

9:30

the possibility of extraterrestrial life

9:32

is real. In sharp contrast

9:34

to the people who agreed with Heart, the

9:36

astrobiologist camp was populated

9:38

by optimists who reasoned that it

9:40

is simply too unlikely for life to evolved

9:43

only once throughout the entire universe.

9:46

We just needed to hone the way we search for

9:48

aliens, and we would surely find them.

9:51

Cd He evolved is the intelligence gathering

9:53

arm of astrobiology, and set

9:55

about listening for alien transmissions

9:57

by aiming radio telescopes at the center

10:00

of galaxies that seemed likely to host life.

10:04

By the time Michael Hart published his paper

10:06

said he hadn't found anything, and Hart

10:09

included in his article that said

10:11

he was an utter waste of time and resources.

10:14

By that time, many others, including some in

10:16

Congress who funded things like st tended

10:18

to agree that there is little justification

10:21

for twelve million dollars taxpayer

10:24

dollars to be expended for this program.

10:27

Madam President, I urge my colleagues

10:29

to vote in favor of this amendment, and

10:32

I reserve the balance of my time

10:34

and yield the floor, and I thank the chair. Yet

10:37

neither hearts paper nor sti's empty handed

10:39

searches have settled the mystery of the

10:41

family paradox. Because

10:43

we've gotten better at observing our universe,

10:46

this little mystery has only gotten more

10:48

weird. Thanks to space

10:50

based telescopes like the Kepler and

10:52

new methods we've developed for watching stars,

10:55

we found that there are a mind boggling number

10:58

of potential earthlike planetile there.

11:01

To qualify as a potential host for life,

11:03

the planet has to check some boxes. The

11:06

star that it orbits has to be of a certain type,

11:08

and in what's called its main sequence, it

11:11

helps to be around the size of our Sun, which

11:13

is right in the middle. Size Wise, big

11:16

stars go through their fuel too quickly to give

11:18

life a reasonable amount of time to emerge.

11:21

On the other end, smaller stars don't

11:23

burn quite warmly enough. The

11:25

planet has to be a particular distance from

11:27

the star. Too too close and any

11:30

life would be burned to a crisp Too far

11:32

away, and the star's warmth couldn't overcome

11:34

the unbearable cold of outer space. Either

11:37

way, the conditions wouldn't allow for water

11:40

to form or an atmosphere, both

11:42

of which we assume are requirements for life

11:44

to emerge. The planet needs

11:46

to be in a spot relative to the Sun that's

11:48

not too hot and not too cold, but

11:51

just right for life. So

11:53

it may not come as much of a surprise that some

11:55

astronomers call this area the Goldilocks

11:58

zone. Taking all of this in to

12:00

account, there are perhaps tens

12:02

of billions of potentially habitable

12:04

planets in the Milky Way alone,

12:08

and it gets even weirder. Throughout

12:10

the decades that people have attempted to resolve

12:13

the family paradox, those attempts

12:15

have always been focused on our galaxy,

12:17

specifically, the rest of the universe

12:19

is just too big to allow for the time

12:21

it would take for another civilization to

12:23

travel to the Milky Way and make its presence known

12:25

to us. So by leaving out the other

12:28

hundred billion galaxies in the universe

12:30

and there's seventy billion trillion stars,

12:33

the idea that perhaps other life might

12:35

exist outside our own galaxy was

12:37

allowed to stay aglow as a faint member

12:39

of possibility, But in two

12:41

thousand thirteen that ember was snuffed too.

12:44

A pair of philosophers from Oxford figured

12:47

out that the math shows there has been plenty of

12:49

time for intergalactic civilizations

12:51

to have evolved and traveled to our galaxy

12:53

too. This is one

12:55

of those Oxford philosophers under

12:58

Samberg, actually suppose

13:00

you wanted to go out and colonized as

13:02

far as you could, how far could you

13:04

go? And we found that you can

13:06

literally do this over billions

13:09

of light years, which means

13:11

that this is also something aliens

13:13

could have done. So if it's a

13:15

bit weird that we haven't noticed

13:17

in the alien spreading across the Milky Way,

13:20

now we need to take into account. But actually

13:22

there are also millions or billions

13:24

of galaxies where aliens could have come

13:27

from but they haven't shown up yet.

13:30

So when we finished that paper, we kind of pointed

13:32

out that we made the Fermi paradox a million

13:34

or a billion times worse. The

13:37

Family paradox extends not only

13:39

to our galaxy, but it seems to

13:41

the entire visible universe.

13:56

Hm to a lot

13:58

of people who think about this kind thing, it's

14:00

simply too outlandish to believe

14:03

that we are the only intelligent life in the entire

14:05

universe, and so over the years,

14:08

people have put forth some interesting answers

14:10

to the family paradox on the basis

14:12

that there is intelligent life out there,

14:14

we just don't know it yet. At

14:17

the most basic level, the arguments consists

14:20

of the notions that aliens either can't

14:22

or won't make the trip to see us. Aliens

14:26

have had plenty of time to colonize the galaxy

14:28

and even the universe, as we've seen, even

14:30

considering travel at less than the speed

14:32

of light, even travel at ten

14:34

percent the speed of light shall allow for the Milky

14:37

Way to be colonized in fifty million years

14:39

at the most. But even allowing

14:42

for plenty of time to make the trip, it's

14:44

entirely possible that the trips between

14:46

stars and galaxies is extremely

14:48

difficult, so difficult in fact,

14:50

that no intelligent civilization has

14:53

ever successfully managed it, although

14:55

plenty may have tried and lost a lot of their people

14:57

to be impossibly hazardous trips before

15:00

finally giving up. Space

15:02

is far from empty. It's full of tiny

15:04

particles called cosmic dust, raw

15:07

material that planets are made from.

15:09

There's a dust cycle out in space where

15:11

dust is blasted into space by exploding

15:14

stars. This dust fills space,

15:16

and even though it consists of extremely

15:18

tiny particles, it would pose a hazard

15:21

to any spacecraft traveling at some significant

15:23

fraction of the speed of light, which again,

15:26

remember something like six hundred and fifty

15:28

million miles an hour. Even

15:30

a tenth of that is still sixty five million

15:32

miles per hour. At these speeds,

15:35

the spacecraft kinetic energy is so unimaginably

15:38

huge that a collision with even some

15:40

tiny piece of matter would be catastrophic.

15:43

MT physicists calculated that impacting

15:46

even a single grain of cosmic dust would

15:48

be tantamount to the explosion of something like

15:50

two and a half tons tons of

15:53

T and T aboard the ship, and

15:57

cosmic dust is just one hazard that

15:59

space bearing species would have to overcome.

16:01

There are surely plenty of others that we haven't

16:03

learned of yet. This argument

16:06

has a flaw to it, though, and I want you to

16:08

pay attention to it, because it's part of

16:10

a theme that really all arguments regarding

16:12

the Family paradox share. If

16:14

the reason aliens haven't colonized the universe

16:17

is because it's extremely hard to travel

16:19

between stars and galaxies, that

16:22

means that it is so hard that

16:24

not one single intelligent civilization

16:27

managed to figure out a way around it, not

16:29

one out of the potentially millions

16:31

or billions or even trillions

16:34

that may have evolved over the life of the universe.

16:37

This is important because to resolve the Family

16:39

paradox, it would take just one of

16:41

them to have learned how to survive the trip, to

16:44

colonize the galaxy and show us that

16:46

we are not alone. And you can

16:48

argue that it would really only take one, one

16:50

single member of one single civilization

16:53

of the potentially trillions of them to make

16:55

it to Earth and make their presence known

16:58

to us to have proof that we are the

17:00

only intelligent life in the universe, which

17:02

makes the Fermi paradox even stranger or

17:06

more clearly settled, depending on your view.

17:09

The other side of that particular coin holds

17:11

that other civilizations could colonize

17:14

the galaxy or even the universe,

17:16

they just don't want to. There

17:18

are a lot of theories as to why that might

17:20

be. Now it's possible we're anthropomorphizing

17:24

aliens here. We humans will

17:26

almost certainly colonize the galaxy if

17:28

we ever get the chance to. So, perhaps

17:30

we're relying too heavily on the assumption

17:32

that any life would. This

17:35

is the senior astronomer at the Study Institute

17:37

set show Stack. All of

17:39

this, all of this is

17:42

based on trying to guess,

17:46

because that's really the correct verb, to

17:48

guess what is important to the

17:50

extraterrestrials. And I don't think

17:52

that we're actually very good

17:55

at that any anymore than

17:57

you know, the ancient Greeks would have been very good

17:59

at guessing it's important to century

18:02

Americans. I don't think that they could

18:04

have seen foreseen the kinds of things that

18:06

would be important to us. Perhaps

18:08

the civilization develops to the point where

18:10

it's technologically capable of interstellar

18:13

and intergalactic travel, it loses

18:15

its taste for such things. Perhaps

18:17

the civilization goes philosophical and

18:20

contemplative a race of beings

18:22

who prefer to spend their time thinking about

18:24

the meaning of life. You're solving the deepest

18:26

mysteries of the universe from home.

18:30

But even the most inward focused society

18:32

would have good reason for expanding from their

18:34

home planet. As their population

18:37

grew, they would need more and more raw

18:39

materials to keep them alive while

18:41

they sat around in contemplated life.

18:44

It would be more space, more energy.

18:47

The need for scarce resources appears to

18:49

be one of the few universal commonalities

18:51

that any civilization will have to deal with. This

18:54

is good. This means that we can pretty confidently

18:57

use this clue to predict the behavior

18:59

of any intelligen life. Then we

19:02

humans run into limitations on our ability

19:04

to grow or make food, so we need

19:06

more space for that. We need space

19:08

for our bodies as well, since each

19:10

person needs somewhere around one point six

19:13

one point seven meters of physical space

19:15

to stand up and extend our arms with him,

19:18

plus we tend to like a little extra to move

19:20

around into. Requirements

19:23

like these mean we would eventually face the prospect

19:25

of either systematically curtailing our population

19:28

growth to maintain no more than what the

19:30

Earth can support and based

19:32

on all current and historical data, we

19:35

tend to overstrain the planet rather than work within

19:37

its confines, or

19:39

we can spread out. It's

19:41

difficult to imagine that any advanced society

19:44

faced with resource pressures would not look

19:46

out to at least their own solar system

19:48

as a source of material solutions to their

19:50

problems. This

19:53

scenario extends further and further, both

19:55

into space and time. As

19:57

the society continued to grow, they

19:59

would take up more and more space, and

20:02

over long enough spans of time, they should reasonably

20:04

have colonized a sizeable chunk of their galaxy,

20:07

if not the whole thing, even with their

20:09

desire to remain inward over so

20:11

many generations. But

20:13

maybe aliens have good reason to resist the

20:16

urge to spread out. Maybe

20:18

they're hiding from something, Maybe

20:20

they know something that we don't know. One

20:44

of the long standing theories about why

20:46

a civilization with the capability of

20:48

traveling to other stars would opt not to is

20:51

the idea that they might be afraid of something. Perhaps

20:54

there's some older civilization that

20:56

doesn't like to compete for scarce resources

20:58

with young upstarts like ourselves, the

21:01

first civilization to have colonized the galaxy

21:03

would have all the advantage over any

21:05

others that came later, even

21:08

considering a hundred thousand year head start,

21:10

which though it's tough to remember that

21:12

the cosmic time scales we're dealing with here

21:15

is the blink of an eye, and earlier

21:17

civilization would have time to see the galaxy

21:19

with things like berserker probes, hypothetical

21:22

type of self replicating space probe

21:24

designed to attack and destroy entire

21:27

civilizations. These

21:29

berserker probes would be capable of strangling

21:32

in the cradle the colonial aspirations

21:34

of any younger civilizations before they

21:36

ever got started. Right

21:38

about where we humans are in our progress right

21:40

now. What's ironic

21:43

about berserker probes is that they can

21:45

produce their own solution to the family paradox

21:47

without even existing. We

21:49

humans thought of the possibility that they could

21:52

exist, so it stands to reason

21:54

that other intelligent civilizations might

21:56

too. It's possible that

21:58

part of the process of the umbing and intelligent

22:01

society engaged with the unknowns

22:03

of the universe is to start having second

22:05

thoughts about signaling into the void

22:08

and instead to go silent. Eventually,

22:11

every single one of these societies might

22:13

stop attempting to communicate and resigned

22:16

to just sitting and listening instead. So

22:19

the universe could be teeming with intelligent

22:21

civilizations, each being quiet

22:23

as a dormouse, each listening and

22:26

unaware of the existence of the others, and

22:29

the berserker probes wouldn't even have to

22:31

exist beyond the hypothetical for this

22:33

solution to the family paradox to work.

22:36

But if berserker probes do exist, why

22:38

wouldn't we have had an unpleasant visit from

22:40

them by now? Transmissions from

22:42

our radio and TV shows have been traveling through

22:45

space since we first started broadcasting here

22:47

on Earth in the early twentieth century,

22:49

and steady researchers have been actively shouting

22:52

at other star systems with radio since

22:54

the sixties. Probably

22:56

the most unsettling answer is that we

22:58

did get their attention, and they're on their way.

23:01

They just haven't had time to reach us yet, or

23:05

perhaps they don't much care about us so

23:08

long as we stay here on Earth or even

23:10

within our own galaxy. In

23:12

two thousand and seventeen, Oxford philosophers

23:15

Stuart Armstrong, Ander Samburg, and

23:17

Milan Turkovich developed a new explanation

23:20

for the Fami paradox that says that

23:22

perhaps the universe does contain berserker

23:24

probes, but rather than actively patrolling

23:26

the galaxy, they are posted on the outskirts

23:29

of some ancient civilizations state territory

23:32

while the civilization sleeps. This

23:35

new idea, called the estivation hypothesis,

23:38

supposes that the civilization in question

23:40

has reached a post biological state.

23:43

Post biological civilizations are their

23:46

own can of worms entirely, and we'll

23:48

talk about them more later on. But

23:50

what they amount to is a species that has

23:52

shed its biological form,

23:54

whether it's an upright bipedal form

23:56

like us humans, a giant root, vegetable,

23:59

whatever, and has preserved its

24:01

minds into a computerized form.

24:04

There are myriad advantages to this. Less

24:06

physical space is needed, you don't need to

24:08

grow food. But these civilizations

24:11

are not free from scarcity either. Here's

24:13

philosopher Ander Samberg again. So

24:16

suppose you're a really advanced civilization.

24:19

You've been around for millions of years, you kind

24:21

of explored in the galaxies, You've

24:23

done most of a big physical stuff.

24:26

At this point, probably most of what you want

24:28

to do is going to be kind of cultural.

24:31

We have no idea as umus what an advancedivils

24:34

might want to do. But I think it's a pretty

24:36

certain bet that it's going to require

24:38

competitions of some kind. Information

24:41

processing a k. A. Computing

24:43

has its own requirements. It needs

24:45

energy and it produces waste

24:48

heat, two huge factors that a

24:50

post biological society would come up against

24:52

as it uploaded more and more of its population

24:55

to a digitized format. Rather

24:58

than food, water, and couple

25:00

of square meters of physical space, they

25:02

would need processing power and speed

25:05

to keep their digitized minds humming along

25:07

and to simulate the world for them.

25:10

So a post biological society would

25:12

have very good reason to colonize their galaxy

25:15

in search of more raw materials to build

25:17

hardware and to harness more energy

25:19

from They will probably

25:22

build massive engineering projects to capture

25:24

energy from entire stars,

25:26

like through some variation of Dicen spheres

25:29

to a hypothetical energy collection

25:31

machine that could be constructed around

25:33

a star to capture some enormous fraction

25:35

of its energy. They may

25:37

deconstruct entire planets to build

25:40

those Dicen spheres, so they may

25:42

have energy and aces. But

25:44

at some point a post biological society

25:47

might strike upon a seemingly insurmountable

25:49

truth about information processing. Regardless

25:52

of how efficient it is, computing

25:55

produces some amount of waste heat. This

25:58

can be tricky enough with a single server him

26:00

here on Earth in the early twenty one century,

26:02

those racks of servers have to be cooled with fans,

26:05

and the room has to be air conditioned. So

26:07

that means that not only is the actual process

26:09

of computing taking up energy, there's

26:12

an additional energy expenditure required

26:14

to keep the hardware cool. Heat

26:16

is the sworn enemy of efficient information

26:19

processing, and efficient information

26:21

processing would be the lifeblood

26:24

in the oxygen to a healthy post

26:26

biological society, So

26:28

keeping heat to a minimum would be of the

26:30

utmost importance. You

26:33

may say, and I would agree with you.

26:35

That's certainly a post biological civilization

26:38

with a hundred thousand or million or

26:40

billion year head start on us would

26:42

have almost certainly figured out better, more

26:44

efficient, and less heat producing methods

26:47

for information processing than the computers

26:49

we humans have hit upon today. It

26:52

would be one of the more surprising things in this

26:54

whole series if that weren't the case. But

26:57

when you begin to scale up from the level of

26:59

server room on word to capturing

27:01

the energy of an entire star, even

27:04

an almost efficient

27:06

computer will still have a massive

27:08

waste heat issue, and that post

27:10

biological society will have to deal with

27:12

it, and that problem is compounded

27:15

with each new star and each new piece

27:17

of hardware that's added. Since

27:19

you have a finite amount of energy,

27:22

even if you're a really big supercivilization,

27:24

that means that the total amount of competition

27:27

you can do is going to be set by temperature. So

27:30

if you wait until the universe gets colder,

27:32

you can get much more competition done.

27:35

Some people have suggested that perhaps

27:37

the edge of the galaxy, which butts

27:39

up against the coldest regions of intergalactic

27:42

space, is the best place to look

27:44

for other civilizations, since they will

27:46

have likely set up shot there to deal with their

27:48

massive waste heat problem. But

27:50

that Oxford group realized that the optimal

27:52

place for a post biological society

27:55

to best deal with their waste heat is

27:57

somewhere in time, not space.

28:00

M One

28:15

popular suggestion for the expiration

28:18

data of the universe comes about ten

28:20

billion thousand years from now via

28:22

the heat death of the universe. Every

28:25

bit of energy in the universe was released

28:27

in the Big Bang some thirteen point seven

28:29

billion years ago, and the ninete

28:32

century we humans it upon the

28:34

laws of thermodynamics, which

28:36

had some bad news about that energy.

28:39

Over time periods, that energy

28:41

will cease as the heat differentials

28:43

that produce it begin to equalize.

28:47

As every atom in the universe slowly

28:49

stops moving, the universe will

28:51

cool, and eventually the universe

28:53

will experience the death of heat, and

28:56

with the cessation of the movement of atoms

28:58

and the particles that make them up, not

29:00

life, not computing, nothing

29:03

will be possible any longer. Long

29:06

before the expiration date, the universe

29:09

will still be alive with energy, but much

29:11

much colder than it is now. So

29:14

particularly clever post biological

29:16

society might realize that the energy

29:18

they have available to them could be captured

29:20

and stored for use later on, when

29:22

the universe is colder and computing

29:25

is, by extension far more efficient.

29:28

So perhaps they built themselves a galaxy's

29:30

worth of Dyson's fears to collect and store

29:32

the energy from their stars while the society

29:35

went to sleep for a billion or so years.

29:37

Even a peaceful post biological society

29:40

would be forced to protect their energy allotment

29:42

and their hardware while they slept, and

29:45

so they would almost certainly post some sort of

29:47

guard like berserker probes to

29:49

watch over them and the civilization they'd arranged

29:51

in store for themselves while they slept. Estivation

29:55

is a kind of hibernation that

29:57

some animals do when it's hot out, and

30:00

the estivation hypothesis goes fairly

30:02

far and entering the family paradox. We

30:05

haven't been colonized by other civilizations

30:07

because they're sleeping, So the estivation

30:10

hypothesis is that advanced civilizations

30:12

might actually think that it's too sweltering

30:14

hot right now, it's three degrees above

30:17

absolute zero, so they

30:19

decide to just hide and estivate

30:23

until it's cold enough. So

30:25

in about one point five trillion

30:27

years, it turns out that the universe

30:29

stops getting colder because of

30:31

the background radiation from the horizon,

30:34

and at that point it might be rational for the super

30:36

civilizision of wake up and they kind

30:38

of feel the nice, crisp autumn

30:41

air or in this case, the

30:43

very cold vacuum of a very far

30:45

future, and start really running

30:47

recipilizations. And this might

30:49

be an explanation of why we're not seeing any

30:52

but it doesn't fully resolve the family paradox

30:54

either. We should still be able to observe

30:57

their dicense fears or other massive engineering

30:59

projects encircling

31:01

a star with an energy capturing devices

31:03

no small feat. We should be able

31:05

to sense such a thing, And indeed, the team

31:08

of Japanese researchers scanned a portion

31:10

of the sky to look for telltale signs

31:12

of dicense fheares stars that produce

31:14

a normal amount of heat but are unnaturally

31:17

dim or even totally dark. They

31:19

didn't find any, So it doesn't

31:22

look exactly like the universe is currently

31:24

full of sleeping elder

31:26

civilizations looking for

31:28

Disonian artifacts. These massive

31:30

engineering projects is a proposed new branch

31:33

of CETI. Whether civilization

31:35

is active, sleeping or extinct,

31:37

the projects they created would likely

31:40

endure, and if we can find those,

31:42

we found our answer to the family paradox.

31:45

But yet again we have found nothing of

31:47

the sort. We have an uncovered

31:49

one scrap of evidence the universe

31:51

has ever been colonized. The

31:53

Fermi paradox stands stronger

31:55

than ever. But

31:58

what if what we're seeing is an actually the reality

32:01

of the universe. What if we're

32:03

being actively manipulated that

32:05

somewhere out there the universe is indeed

32:07

teeming with life, that there are widespread

32:10

engineering projects that litter the galaxies.

32:12

We just can't see any of it because we're

32:14

being prevented from seeing things as they

32:17

really are. This

32:19

is the basis of a family of answers to

32:21

the Family paradox called the Zoo hypothesis,

32:24

thought up in nine three by m

32:26

I t astronomer John Ball. It

32:28

supposes that we humans are being kept

32:31

without our knowledge and some sort of cosmic

32:33

zoo, and being observed, maybe

32:35

even studied, without our awareness.

32:38

Perhaps we're being kept in a kind of nature

32:41

preserve until we reach some crucial

32:43

point in our evolution when the secrets

32:45

of the universe will be revealed to us.

32:49

Or maybe we're meant to stay in a naturally

32:51

preserved state forever. Maybe

32:53

the rest of the universe has been paved over

32:55

with dicens fears, every other available

32:58

planet stripped and deconstructed for materials,

33:01

and out of a sense of intergalactic nostalgia,

33:04

our planet and the life on it, including us,

33:06

has been selected to be kept in a pristine

33:09

state. The Zoo hypothesis

33:11

has some holes in it too, mostly

33:14

the same as any other solution to the Family paradox.

33:17

It would take only one member of one civilization

33:20

to shatter it. The Zoo hypothesis

33:22

presumes some sort of star Trek

33:25

like prime directive to leave us alone,

33:27

and it would have to be firmly upheld

33:29

by all other civilizations in this

33:31

galactic club, keeping us

33:33

in the dark for as long as humans have been around.

33:36

There are no options. The prime directive

33:39

is not a matter of degrees, it

33:41

is an absolute, one would think. Some

33:44

people object to this dismissal of the zoo

33:46

hypothesis. They point to things

33:48

like UFO sightings and historical

33:51

documentation of inexplicable phenomena

33:54

like the fifteen sixty one Cathedral

33:56

of Light over Nuremberg, Germany.

33:58

All of this is evidence of past non compliance

34:01

with this prohibition on contact with us

34:03

humans. It's also possible

34:05

that Earth was visited in human prehistory

34:07

as well, and that there's just no surviving

34:10

evidence of it. Or maybe

34:12

we have received messages and just don't know it

34:14

yet. Perhaps they are encoded in

34:16

our DNA, waiting for us to find

34:18

them and make sense of it. There

34:21

is something very disconcerting about the zoo

34:23

hypothesis, the idea that

34:25

knowledge we would very much like to have is

34:28

being kept from us without our say in the matter,

34:31

through ways we may never hope to overcome

34:33

on our own. But I

34:35

don't know. Is that better or worse than

34:37

the alternative? Is the idea

34:40

that we are being manipulated by a galactic

34:42

club of civilizations better or

34:44

worse than the idea that there are no

34:46

other civilizations at all. There

34:49

is a very reasonable alternative explanation

34:52

to the Faramie paradox, one that

34:54

requires us to make the fewest leaps of faith

34:56

to reach it. That we are utterly

34:59

and entirely alone in

35:01

the universe. This is

35:03

Oxford philosopher Toby Ord.

35:05

There are about two hundred billion

35:08

stars in our galaxy the Milky

35:10

Way. So if

35:13

the chance of life or intelligent

35:16

life evolving around any one of those stars

35:19

was was even you know, one in a billion, you'd

35:21

expect that to be about two

35:24

hundred stars in our galaxy that

35:26

have involved intelligent life. And

35:28

yet when we look around, we see no signs of

35:30

this, and we also don't see any signs of it

35:32

in other galaxies um that we have looked

35:34

at. Some people think

35:37

that this is a paradoxical

35:39

result, but I think it's actually

35:42

much more likely that the that

35:45

it's just that there aren't any As

35:47

Michael Hart puts it, in this Our

35:51

universe is too big and too old

35:53

for it not to be teeming with life by now.

35:56

That we've not seen evidence of other civilizations

35:59

suggests that they do not exist,

36:02

but that's not to say they never did. Perhaps

36:05

we don't see other intelligent civilizations

36:08

because none of them have survived. On

36:24

the next episode of the End of the World

36:26

with Josh Clark, the great filter

36:28

is whatever is in the way, whatever

36:31

makes it hard for any one piece of ordinary

36:33

dead matter to produce expanding, lasting

36:36

life. If we are alone in the universe,

36:39

then perhaps there's something that's killed off

36:41

every other civilization before it

36:43

could spread from its home planet. And

36:45

if that's true, can we expect

36:47

the same in our future?