0:02:02.805,0:02:05.537
(Narrator)[br]To have any hope of finding alien life,

0:02:05.537,0:02:07.408
we have to know what to look for.

0:02:12.060,0:02:13.945
But where do we begin?

0:02:15.303,0:02:19.380
How do we narrow down a[br]seemingly infinite set of possibilities?

0:02:27.340,0:02:29.178
There's one thing we know for sure:

0:02:30.683,0:02:33.357
nature will have to play by her own rules.

0:02:36.791,0:02:39.807
No matter how strange alien life might be,

0:02:40.386,0:02:43.826
it's going to be limited by the same[br]physical and chemical laws

0:02:43.826,0:02:44.747
that we are.

0:02:51.613,0:02:52.753
On top of this,

0:02:53.233,0:02:55.684
each alien environment will further limit

0:02:55.684,0:02:58.026
what kinds of lifeforms can evolve there.

0:03:06.802,0:03:10.125
Despite these natural boundaries,[br]the possibilities

0:03:10.125,0:03:12.196
are staggering to imagine.

0:03:14.235,0:03:15.764
Trillions of planets,

0:03:15.764,0:03:17.924
each a unique cauldron of chemicals

0:03:17.924,0:03:20.640
undergoing their own complex evolution.

0:03:28.180,0:03:29.704
To guide our thinking,

0:03:29.704,0:03:33.565
this museum of alien life[br]will be divided into two exhibits:

0:03:35.668,0:03:37.285
life as we know it,

0:03:37.285,0:03:40.990
home to beings[br]with biochemistries like ours;

0:03:41.694,0:03:44.068
and life as we don't know it,

0:03:44.068,0:03:46.538
home to beings that challenge our concept

0:03:46.538,0:03:47.858
of life itself.

0:03:54.022,0:03:57.103
Before we venture too far into[br]the unknown,

0:03:57.103,0:03:58.727
we have to ask ourselves:

0:03:59.956,0:04:01.128
what if alien life

0:04:01.128,0:04:03.108
is more like us than we think?

0:04:15.224,0:04:17.297
If there's one feature that unites us

0:04:17.297,0:04:19.922
with the other specimens in this museum,

0:04:19.922,0:04:21.245
it's carbon.

0:04:24.730,0:04:26.638
(Nick Lane)[br]Carbon is ubiquitous,

0:04:26.638,0:04:29.515
it's one of the most common[br]elements in the universe,

0:04:29.515,0:04:32.822
and it's very good at forming[br]large, stable molecules.

0:04:37.179,0:04:39.357
(Narrator)[br]Carbon has the rare ability to form

0:04:39.357,0:04:41.643
four-way bonds[br]with other elements,

0:04:41.643,0:04:42.863
and to bind to itself

0:04:42.863,0:04:44.613
in long, stable chains,

0:04:46.261,0:04:49.627
enabling the formation of[br]huge complex molecules.

0:04:56.157,0:04:59.123
This versatility makes carbon[br]the centerpiece

0:04:59.123,0:05:01.130
in the molecular machinery of life.

0:05:03.260,0:05:06.110
And the same carbon compounds[br]that we use

0:05:06.110,0:05:07.876
have been found far from Earth,

0:05:08.546,0:05:10.028
clinging to meteorites,

0:05:12.160,0:05:14.404
and floating in far-off clouds

0:05:14.404,0:05:15.712
of cosmic dust.

0:05:18.480,0:05:19.964
The building blocks of life,

0:05:21.167,0:05:23.628
drifting like snow through the universe.

0:05:29.992,0:05:32.052
And if alien life has selected

0:05:32.052,0:05:34.950
other carbon compounds for their[br]biochemistry,

0:05:35.573,0:05:37.337
they will have plenty to choose from.

0:05:41.958,0:05:43.820
Scientists recently identified

0:05:43.820,0:05:47.585
over a million possible alternatives[br]to DNA—

0:05:48.448,0:05:49.859
all carbon-based.

0:05:57.678,0:05:58.950
If we ever discover

0:05:58.950,0:06:01.492
other carbon-based lifeforms,

0:06:01.492,0:06:03.811
we would be fundamentally related.

0:06:07.740,0:06:09.889
They would be our cosmic brethren.

0:06:13.196,0:06:15.193
But would they look anything like us?

0:06:19.685,0:06:22.087
If they hail from Earth-like planets,

0:06:22.607,0:06:24.915
we could share even more in common

0:06:24.915,0:06:26.602
than just our biochemistry.

0:06:29.686,0:06:32.188
(Jonathan Losos)[br]What would life be like on other planets,

0:06:32.188,0:06:33.466
if it is evolved?

0:06:33.466,0:06:34.706
Would it be like

0:06:34.706,0:06:36.252
the world today here on Earth,

0:06:37.362,0:06:39.102
or would it be completely different?

0:06:40.409,0:06:42.206
There are those who argue that,

0:06:42.206,0:06:44.713
from the argument of convergent evolution,

0:06:44.713,0:06:47.534
if conditions on other planets are[br]similar to here,

0:06:47.534,0:06:50.169
then we would see very similar life forms—

0:06:54.576,0:06:58.169
animal- and plant-like organisms[br]that look very familiar.

0:07:12.048,0:07:14.206
(Narrator)[br]On Earth, certain features like

0:07:14.206,0:07:16.768
eyesight, echolocation, and flight

0:07:16.768,0:07:19.492
have evolved multiple times independently

0:07:19.492,0:07:20.797
in different species.

0:07:23.648,0:07:26.385
This process of convergent evolution

0:07:26.385,0:07:29.120
could extend to alien planets like Earth,

0:07:29.120,0:07:32.114
where creatures face similar environmental[br]pressures.

0:07:35.412,0:07:37.170
It's no guarantee,

0:07:37.170,0:07:38.229
but there could be

0:07:38.229,0:07:40.544
certain universalities of life.

0:07:44.177,0:07:48.542
The greatest hits of evolution[br]on repeat across the universe.

0:07:57.720,0:08:01.130
Each feature would be attuned[br]to its local environment.

0:08:02.808,0:08:04.185
Dimly lit planets

0:08:04.185,0:08:07.985
would produce huge eyes to suck in[br]extra light,

0:08:07.985,0:08:09.585
like nocturnal mammals.

0:08:14.090,0:08:16.589
(Jonathan Losos)[br]Some people have gone so far as to say

0:08:16.589,0:08:18.526
that human-type organisms,

0:08:18.526,0:08:19.261
humanoids,

0:08:19.261,0:08:20.912
will occur on other planets.

0:08:25.886,0:08:27.146
The existence of other

0:08:27.146,0:08:30.025
humanlike organisms seems unlikely,

0:08:30.025,0:08:32.604
given the long, convoluted[br]chain of events

0:08:32.604,0:08:33.624
that produced us.

0:08:35.016,0:08:36.398
But we can't rule it out.

0:08:40.610,0:08:44.368
If just one in every[br]hundred trillion Earth-like planets

0:08:44.368,0:08:46.324
produced a humanlike form,

0:08:46.324,0:08:47.284
there could still be

0:08:47.284,0:08:49.586
thousands of creatures like us out there.

0:09:10.051,0:09:11.378
Convergent evolution

0:09:11.378,0:09:13.877
is also rampant in plant life,

0:09:13.877,0:09:17.540
and C₄ photosynthesis has arisen[br]independently

0:09:17.540,0:09:19.424
over 40 times.

0:09:21.619,0:09:23.607
Would alien plants look like ours

0:09:23.607,0:09:25.460
or something else entirely?

0:09:36.696,0:09:38.862
On Earth, plants appear green

0:09:38.862,0:09:40.867
because they absorb the other wavelengths

0:09:40.867,0:09:42.667
in the Sun's light spectrum.

0:09:45.432,0:09:47.961
But stars come in many colors,

0:09:52.249,0:09:54.752
and alien plants would evolve[br]different pigments

0:09:54.752,0:09:57.003
to adapt to their sun's unique spectrum.

0:10:04.321,0:10:06.427
Plants feeding off hotter stars

0:10:06.427,0:10:07.670
could appear redder,

0:10:08.184,0:10:10.126
by absorbing their energy-rich

0:10:10.126,0:10:11.126
bluer light.

0:10:19.561,0:10:22.110
Around dim red dwarf stars,

0:10:22.110,0:10:24.300
vegetation could appear black,

0:10:24.962,0:10:26.211
adapted to absorb

0:10:26.211,0:10:28.378
all visible wavelengths of light.

0:10:44.948,0:10:45.990
Earth itself

0:10:45.990,0:10:47.853
may have once appeared purple,

0:10:47.853,0:10:49.795
due a pigment called retinal

0:10:49.795,0:10:52.126
that was an early precursor[br]to chlorophyll.

0:10:54.869,0:10:58.049
Some think that[br]retinal's molecular simplicity

0:10:58.049,0:11:00.682
could make it a more universal pigment.

0:11:03.680,0:11:04.986
If so,

0:11:04.986,0:11:06.629
we may find that purple

0:11:07.603,0:11:09.507
is life's favorite color.

0:11:19.717,0:11:21.770
But the color of alien vegetation

0:11:21.770,0:11:23.783
is more than just a curiosity—

0:11:25.526,0:11:27.025
it's chemical information

0:11:27.025,0:11:29.347
that can be seen from lightyears away.

0:11:34.388,0:11:36.512
Earth plants leave a signature "bump"

0:11:36.512,0:11:38.602
in the light reflected off our planet.

0:11:40.076,0:11:42.529
Finding a similar signal[br]from another world

0:11:42.529,0:11:44.917
could point the way to alien vegetation.

0:11:50.256,0:11:51.631
Perhaps this will be

0:11:51.631,0:11:54.390
our first glimpse at alien life:

0:11:54.865,0:11:58.462
a vibrant hue cast by a distant world.

0:12:20.525,0:12:22.096
(Caleb Scharf)[br]What happens when you change

0:12:22.096,0:12:23.295
the day length of a planet?

0:12:23.295,0:12:24.368
What happens when you change

0:12:24.368,0:12:25.545
the tilt of a planet?

0:12:25.545,0:12:26.537
What happens when you change

0:12:26.537,0:12:27.835
the shape of the orbit?

0:12:27.835,0:12:29.126
What happens when you change

0:12:29.126,0:12:30.521
the gravity of a planet?

0:12:34.488,0:12:37.148
(Narrator)[br]Planets with long, elliptical orbits

0:12:37.148,0:12:39.860
would see drastic seasons.

0:12:41.298,0:12:42.300
There could be worlds

0:12:42.300,0:12:45.458
that appear dead for thousands of years,

0:12:45.458,0:12:47.581
then suddenly spring to life.

0:13:02.473,0:13:05.058
Most of the rocky planets[br]discovered so far

0:13:05.058,0:13:07.078
have been massive "super-Earths".

0:13:12.557,0:13:15.960
How would life evolve on these worlds?

0:13:18.540,0:13:19.566
In the seas,

0:13:19.566,0:13:21.752
gravity may not matter much at all.

0:13:29.470,0:13:30.670
(Unnamed)[br]A high-gravity planet

0:13:30.670,0:13:32.192
isn't high-gravity all over.

0:13:33.590,0:13:36.257
If you're in the sea[br]and that's where all life starts,

0:13:36.257,0:13:37.690
there's very nearly no gravity

0:13:37.690,0:13:40.505
'cause you're much the same density[br]as the stuff around you.

0:13:43.310,0:13:45.637
It's when the animals come out on land,

0:13:45.637,0:13:47.169
that they feel the gravity.

0:13:51.518,0:13:53.570
(Narrator)[br]High g-forces would necessitate

0:13:53.570,0:13:55.633
large bones and muscle mass

0:13:55.633,0:13:57.546
in complex life on land.

0:13:59.748,0:14:00.836
They would also demand

0:14:00.836,0:14:03.209
a more robust circulatory system.

0:14:04.773,0:14:06.520
And plant life could be stunted

0:14:06.520,0:14:09.019
by the energy cost of carrying nutrients

0:14:09.019,0:14:10.584
under stronger gravity.

0:14:17.168,0:14:18.547
Low-gravity planets

0:14:18.547,0:14:21.798
would more easily[br]lose their atmospheres to space,

0:14:21.798,0:14:23.337
and lack a magnetic field

0:14:23.337,0:14:25.443
to protect from cosmic rays.

0:14:35.751,0:14:37.605
But smaller worlds could be home

0:14:37.605,0:14:39.404
to secret oases:

0:14:46.161,0:14:47.503
huge cave systems

0:14:47.503,0:14:49.544
that provide hideouts for life.

0:15:26.691,0:15:29.353
The smallest possible habitable planets

0:15:29.353,0:15:31.897
are estimated at 2.5%

0:15:31.897,0:15:33.312
Earth's mass.

0:15:35.002,0:15:37.793
If surface life does evolve[br]on these worlds,

0:15:38.742,0:15:40.627
it could be a sight to behold.

0:15:44.584,0:15:47.394
Plant life could grow to towering heights,

0:15:47.394,0:15:50.460
able to carry nutrients higher[br]in lesser gravity.

0:15:59.044,0:16:00.160
And without the need

0:16:00.160,0:16:02.754
for bulky skeletons and muscle mass,

0:16:02.754,0:16:04.511
animals could have body types

0:16:04.511,0:16:06.170
that boggle the mind.

0:16:31.391,0:16:32.310
Here on Earth,

0:16:32.310,0:16:34.835
it took three billion years for evolution

0:16:34.835,0:16:37.404
to produce complex plant and animal life.

0:16:39.663,0:16:41.654
Simpler organisms are hardier,

0:16:41.654,0:16:42.716
more adaptable,

0:16:42.716,0:16:44.213
and more widespread.

0:16:48.283,0:16:49.705
The largest collection

0:16:49.705,0:16:51.440
in the museum of alien life

0:16:51.440,0:16:54.419
would likely be the "Hall of Microbes".

0:17:10.116,0:17:12.960
Yet finding even the tiniest alien microbe

0:17:12.960,0:17:15.200
would be a profound discovery.

0:17:30.455,0:17:31.849
And bite-sized life

0:17:31.849,0:17:33.616
could leave a big footprint.

0:17:35.762,0:17:37.327
Like stromatolites on Earth,

0:17:37.327,0:17:39.281
layers of microbes could build up

0:17:39.281,0:17:41.542
into huge rock mounds over time,

0:17:41.542,0:17:44.112
leaving behind eerie structures.

0:17:48.620,0:17:50.412
And in big enough numbers,

0:17:50.412,0:17:52.248
some alien bacteria could leave

0:17:52.248,0:17:54.134
a distinct biosignature

0:17:55.874,0:17:59.293
by exhaling gases that wouldn't[br]coexist naturally,

0:17:59.293,0:18:01.380
like oxygen and methane.

0:18:07.146,0:18:07.919
(Shawn Domagal-Goldman)[br]There's ways to make

0:18:07.919,0:18:09.619
oxygen without life,[br]there's ways to make

0:18:09.619,0:18:10.937
methane without life,

0:18:10.937,0:18:12.939
but to have them in the atmosphere together

0:18:12.939,0:18:14.558
is almost impossible unless you've got

0:18:14.558,0:18:16.581
biology making those gases at the surface.

0:18:17.670,0:18:19.107
And it would have an imprint

0:18:19.107,0:18:20.877
on the planet's spectrum of colors.

0:18:22.695,0:18:24.694
(Narrator)[br]Next-generation space telescopes

0:18:24.694,0:18:26.502
could find a signal like this,

0:18:28.384,0:18:30.751
on a world not far from home.

0:18:32.044,0:18:33.941
(Chris Crowe)[br]The closest Sun-like star

0:18:33.941,0:18:37.757
with an Earth-like exoplanet[br]in the habitable zone

0:18:37.757,0:18:40.419
is probably only 20 light years away,

0:18:40.419,0:18:42.499
and can be seen with the naked eye.

0:19:06.209,0:19:08.209
Most brown dwarfs are too hot

0:19:08.209,0:19:10.086
to support life as we know it.

0:19:10.986,0:19:12.671
But some are just cold enough.

0:19:24.419,0:19:26.235
All the prime elements for life

0:19:26.235,0:19:28.754
have been detected[br]inside their atmospheres.

0:19:31.458,0:19:33.016
And within these clouds,

0:19:33.016,0:19:34.498
some layers would provide

0:19:34.498,0:19:36.340
ideal temperatures and pressures

0:19:36.340,0:19:37.504
for habitability.

0:19:46.073,0:19:48.905
There could be photosynthetic plankton[br]in these skies,

0:19:49.992,0:19:52.585
kept aloft by churning upwinds.

0:19:57.463,0:19:58.780
And with enough force,

0:19:58.780,0:20:00.578
these upwinds could even support

0:20:00.578,0:20:02.916
larger, more complex life.

0:20:06.011,0:20:06.796
Predators.

0:20:44.072,0:20:46.163
This raises a crucial question:

0:20:47.635,0:20:50.439
what if we've been looking in[br]all the wrong places?

0:20:52.523,0:20:55.125
What if nature has other ideas?

0:21:20.931,0:21:24.295
Most of the universe[br]is too cold or too hot

0:21:24.295,0:21:26.420
for liquid water and the biochemistry

0:21:26.420,0:21:28.295
that supports life as we know it.

0:21:31.304,0:21:33.724
But in case our biases are misleading,

0:21:34.520,0:21:36.453
we have to cast a wide net—

0:21:38.748,0:21:42.051
to search for life outside[br]the habitable zone,

0:21:42.051,0:21:45.003
in places that seem wildly hostile to us.

0:21:49.416,0:21:51.348
Exotic environments will demand

0:21:51.348,0:21:53.406
exotic biochemistries,

0:21:53.406,0:21:56.895
and while no element can match[br]carbon's versatility,

0:21:56.895,0:21:58.738
one contender is a frontrunner.

0:22:07.508,0:22:08.624
At first glance,

0:22:08.624,0:22:10.752
silicon seems similar to carbon.

0:22:12.746,0:22:14.933
It forms the same four-way bonds

0:22:14.933,0:22:16.934
and is also abundant in the universe.

0:22:19.216,0:22:21.000
But a closer look reveals that

0:22:21.000,0:22:23.263
these two elements are false twins.

0:22:27.148,0:22:29.138
Silicon bonds are weaker,

0:22:29.138,0:22:32.503
and less prone to forming[br]large, complex molecules.

0:22:36.160,0:22:37.515
Despite this,

0:22:37.515,0:22:40.820
they can withstand a wider range[br]of temperatures,

0:22:40.820,0:22:43.795
opening up intriguing possibilities.

0:22:47.191,0:22:49.238
(Carl Sagan)[br]Life based on the silicon atom,

0:22:49.238,0:22:50.588
instead of carbon,

0:22:50.588,0:22:53.290
would be more resistant to the[br]extreme cold,

0:22:54.568,0:22:56.723
providing a whole new range

0:22:56.723,0:22:58.057
of weird forms.

0:23:01.101,0:23:02.901
(Narrator)[br]But silicon has a problem:

0:23:04.416,0:23:06.215
in the presence of oxygen,

0:23:06.215,0:23:07.936
it binds into solid rock.

0:23:10.127,0:23:12.104
To avoid turning to stone,

0:23:12.104,0:23:14.142
silicon beings might be confined

0:23:14.142,0:23:16.318
to oxygen-free environments,

0:23:16.318,0:23:18.098
like Saturn's frigid moon,

0:23:18.098,0:23:18.811
Titan.

0:23:22.907,0:23:25.674
Its vast lakes of[br]liquid methane and ethane

0:23:25.674,0:23:27.131
could be an ideal medium

0:23:27.131,0:23:29.027
for silicon-based life,

0:23:29.027,0:23:31.646
or other radical biochemistries.

0:23:37.105,0:23:38.743
Without ample sunlight,

0:23:38.743,0:23:41.023
beings on worlds like Titan

0:23:41.023,0:23:43.117
would likely be chemosynthetic,

0:23:43.117,0:23:46.171
deriving their energy[br]by breaking down rocks.

0:24:01.426,0:24:02.883
Such life forms could have

0:24:02.883,0:24:04.720
ultra slow metabolisms,

0:24:04.720,0:24:05.807
and life cycles

0:24:05.807,0:24:07.936
measured in millions of years.

0:24:25.821,0:24:27.114
In high temperatures,

0:24:27.114,0:24:29.631
typically rigid silicon-oxygen bonds

0:24:29.631,0:24:31.903
become more flexible and reactive,

0:24:32.674,0:24:34.918
triggering more dynamic chemistry.

0:24:39.930,0:24:43.456
This has led to a truly bizarre proposal:

0:24:43.456,0:24:45.307
silicon-based lifeforms

0:24:45.307,0:24:48.482
that live inside molten silicate rock.

0:25:00.753,0:25:03.315
In theory,[br]these forms could even exist

0:25:03.315,0:25:06.094
deep beneath the Earth inside[br]magma chambers

0:25:06.094,0:25:08.458
as part of a shadow biosphere.

0:25:12.142,0:25:13.487
If so,

0:25:13.487,0:25:16.669
then the aliens are right under our noses.

0:25:20.559,0:25:23.460
Other shadow biospheres[br]have been proposed—

0:25:23.460,0:25:25.462
forms of life living alongside us

0:25:25.462,0:25:27.338
that we don't even know are here—

0:25:27.338,0:25:31.131
including tiny RNA-based life[br]small enough to go

0:25:31.131,0:25:33.577
undetected by existing instruments.

0:25:46.741,0:25:48.772
Clouds of dust and empty space

0:25:48.772,0:25:50.775
might seem like the last place[br]you'd expect

0:25:50.775,0:25:52.126
to find anything living.

0:25:54.197,0:25:55.585
But when cosmic dust

0:25:55.585,0:25:59.148
makes contact with plasma,[br]a type of ionized gas,

0:25:59.148,0:26:00.911
something strange happens.

0:26:05.550,0:26:07.235
In simulated conditions,

0:26:07.235,0:26:08.943
dust particles have been seen

0:26:08.943,0:26:11.123
spontaneously self-organizing into

0:26:11.123,0:26:13.762
helical structures that resemble DNA.

0:26:18.588,0:26:19.992
These plasma crystals

0:26:19.992,0:26:22.379
even begin to exhibit lifelike behavior:

0:26:23.578,0:26:24.559
replicating,

0:26:24.559,0:26:26.833
evolving into more stable forms,

0:26:26.833,0:26:28.668
and passing on information.

0:27:12.110,0:27:14.796
Plasma is the most common state of matter

0:27:14.796,0:27:15.945
in the universe.

0:27:17.386,0:27:19.856
If complex, evolving plasma crystals

0:27:19.856,0:27:20.966
really exist,

0:27:20.966,0:27:23.122
and if they can be considered life,

0:27:23.122,0:27:25.419
they could be its most common form.

0:27:51.260,0:27:52.919
When massive suns explode,

0:27:52.919,0:27:55.523
some collapse into ultra dense cores

0:27:55.523,0:27:57.041
called neutron stars.

0:27:57.826,0:28:00.158
Hulking masses of atomic nuclei,

0:28:00.158,0:28:02.071
crammed together like sardines.

0:28:05.306,0:28:07.965
Conditions on the surface are[br]mind-boggling—

0:28:08.712,0:28:11.147
gravity is a hundred billion times

0:28:11.147,0:28:12.206
stronger than Earth's.

0:28:15.464,0:28:17.711
But beneath their iron nuclei crust

0:28:17.711,0:28:19.563
lies something strange:

0:28:21.334,0:28:22.796
a hot dense sea

0:28:22.796,0:28:25.504
of neutrons and subatomic particles.

0:28:34.310,0:28:36.396
Stripped of their electron shells,

0:28:36.396,0:28:37.771
these nuclei would obey

0:28:37.771,0:28:40.380
entirely different laws of chemistry,

0:28:40.380,0:28:42.914
based not on the electromagnetic force,

0:28:42.914,0:28:45.047
but the strong nuclear force

0:28:45.047,0:28:46.838
which binds nuclei together.

0:28:49.595,0:28:50.614
In theory,

0:28:50.614,0:28:54.646
these particles could link up to form[br]larger macronuclei,

0:28:54.646,0:28:57.143
which could then combine into even bigger

0:28:57.143,0:28:58.223
"super nuclei".

0:29:06.596,0:29:07.785
If so,

0:29:07.785,0:29:09.535
then this bewildering environment

0:29:09.535,0:29:12.404
would mimic the basic conditions for life—

0:29:12.404,0:29:14.084
heavy nucleon molecules,

0:29:14.084,0:29:16.827
floating in a complex particle ocean.

0:29:22.509,0:29:25.338
Some scientists have proposed[br]the unimaginable:

0:29:26.349,0:29:27.783
exotic life forms

0:29:27.783,0:29:30.953
drifting through the strange particle sea,

0:29:30.953,0:29:33.019
living, evolving, and dying

0:29:33.019,0:29:35.979
on incomprehensibly fast time scales.

0:30:19.336,0:30:20.581
Life is not something

0:30:20.581,0:30:22.628
that has to evolve naturally.

0:30:26.186,0:30:27.454
It can be designed.

0:30:41.406,0:30:43.438
And once intelligence is introduced

0:30:43.438,0:30:46.086
into the evolutionary process,

0:30:46.086,0:30:48.262
a Pandora's box is opened.

0:31:05.977,0:31:08.973
Free from typical biological limitations,

0:31:08.973,0:31:11.003
synthetic and machine-based life

0:31:11.003,0:31:13.086
could be the most successful of all.

0:31:16.507,0:31:18.575
It could thrive almost anywhere,

0:31:18.575,0:31:20.685
including the vacuum of space,

0:31:20.685,0:31:22.543
opening up vast frontiers

0:31:22.543,0:31:25.221
unavailable to biological organisms.

0:31:31.737,0:31:34.941
And compared to the glacial pace[br]of natural selection,

0:31:34.941,0:31:36.834
technological evolution

0:31:36.834,0:31:39.475
allows exponentially faster growth,

0:31:39.475,0:31:41.919
adaptability, and resilience.

0:31:56.067,0:31:59.477
By some estimates,[br]autonomous self-replicating machines

0:31:59.477,0:32:01.770
could colonize an entire galaxy

0:32:01.770,0:32:03.896
in as little as a million years.

0:32:18.687,0:32:21.484
We can't predict how hyperintelligent life

0:32:21.484,0:32:22.978
would organize itself,

0:32:26.367,0:32:27.407
but in theory,

0:32:27.407,0:32:30.013
there could be convergent evolution[br]at play.

0:32:32.177,0:32:34.433
The electrical properties of silicon

0:32:34.433,0:32:36.326
might make it a universal basis

0:32:36.326,0:32:38.002
for machine intelligence,

0:32:38.567,0:32:41.704
a redemption for its biological[br]shortcomings.

0:33:53.263,0:33:55.065
As the universe ages,

0:33:55.065,0:33:57.960
perhaps machine intelligence will come[br]to dominate,

0:33:58.633,0:34:01.040
and naturally occurring biological life

0:34:01.040,0:34:03.748
will be viewed as a quaint starting point.

0:34:09.453,0:34:10.702
Perhaps we ourselves

0:34:10.702,0:34:12.251
will lead this transition,

0:34:12.973,0:34:14.533
and the great human experiment

0:34:14.533,0:34:16.401
would be merely a first link

0:34:16.401,0:34:19.962
in a sprawling intergalactic chain[br]of life.

0:35:27.449,0:35:29.749
Loren Eiseley has said

0:35:29.749,0:35:31.669
that one does not meet oneself

0:35:31.669,0:35:34.347
until one catches the reflection

0:35:34.347,0:35:36.261
from an eye other than human.

0:35:38.665,0:35:40.918
One day that eye may be

0:35:40.918,0:35:42.877
that of an intelligent alien.

0:35:45.662,0:35:47.775
And the sooner we eschew

0:35:47.775,0:35:50.685
our narrow view of evolution,

0:35:52.024,0:35:55.828
the sooner we can truly explore

0:35:55.828,0:35:59.310
our ultimate origins and destinations.

0:36:35.094,0:36:40.089
English captions by[br]vrgtics, ericksoares3, and KillerGhoul