1
00:00:02,233 --> 00:00:06,066
TYSON: In our galaxy, there
may be ships of other worlds
2
00:00:06,200 --> 00:00:10,400
that dare to venture
into the cosmic deep.
3
00:00:12,333 --> 00:00:14,934
Perhaps they travel
from star to star,
4
00:00:15,066 --> 00:00:18,533
searching for worlds
where life has taken hold.
5
00:00:18,667 --> 00:00:22,033
To get a closer look at the
emergent properties of life
6
00:00:22,166 --> 00:00:25,066
that even they can't predict.
7
00:00:26,033 --> 00:00:30,767
This particular vessel is
on just such a survey mission.
8
00:00:32,800 --> 00:00:38,266
Who, scanning this world,
would have pronounced it a
fit nursery for life?
9
00:00:39,834 --> 00:00:43,500
What wild optimist could
have foreseen that peonies
10
00:00:43,633 --> 00:00:48,100
and eagles would one day
spring from this hell hole?
11
00:00:51,867 --> 00:00:55,400
In its infancy,
four billion years ago,
12
00:00:55,533 --> 00:00:59,867
Earth held little
apparent promise.
13
00:01:00,734 --> 00:01:05,066
Now, Venus,
that's more like it.
14
00:01:05,200 --> 00:01:11,033
Back then,
it may have had oceans
and land and possibly life.
15
00:01:15,533 --> 00:01:20,233
This long-ago epoch was
Venus' moment to flourish.
16
00:01:20,367 --> 00:01:23,867
Its time in
the habitable zone.
17
00:01:24,000 --> 00:01:26,700
For any world, that's a
period when its relationship to
18
00:01:26,834 --> 00:01:31,300
its star means that it's
not too hot and not too cold.
19
00:01:32,533 --> 00:01:37,700
It's a time in a world's
existence when it can
foster and sustain life.
20
00:01:39,633 --> 00:01:43,233
But the grace of the habitable
zone is a fleeting thing
21
00:01:43,367 --> 00:01:47,667
and, for no world,
lasts forever.
22
00:01:51,066 --> 00:01:54,100
We reside in our
star's habitable zone,
23
00:01:54,233 --> 00:01:58,834
but it is moving
outwards at the rate of
about three feet per year.
24
00:01:58,967 --> 00:02:03,633
Earth has already
passed through 70% of
its most hospitable time,
25
00:02:03,767 --> 00:02:05,700
but no need to worry,
26
00:02:05,834 --> 00:02:08,800
that stills leaves us
hundreds of millions of years
27
00:02:08,934 --> 00:02:12,767
to plan and execute
our exit strategy.
28
00:02:12,900 --> 00:02:16,700
Where will we go when the
sun's grace leave us behind
29
00:02:16,834 --> 00:02:22,066
for other worlds and Earth
is no longer a garden for life?
30
00:02:22,600 --> 00:02:25,567
Will our species have set
sail for distant islands in
31
00:02:25,700 --> 00:02:29,066
the vast ocean
of the Milky Way?
32
00:02:31,266 --> 00:02:37,200
(theme music plays).
33
00:02:55,867 --> 00:03:02,333
♪ ♪
34
00:03:22,967 --> 00:03:29,734
♪ ♪
35
00:03:33,934 --> 00:03:39,300
(waves crashing).
36
00:03:43,834 --> 00:03:46,734
TYSON: There is no refuge
from change in the cosmos.
37
00:03:46,867 --> 00:03:50,700
No safe place to
hide for more than a few
hundred million years.
38
00:03:51,767 --> 00:03:56,633
Someday, all of
this will surrender to the
churning cycles of birth,
39
00:03:56,767 --> 00:04:01,333
destruction and rebirth
mandated by the laws of nature.
40
00:04:02,133 --> 00:04:05,567
The universe evolves
beautiful things then smashes
41
00:04:05,700 --> 00:04:09,834
them to bits before
making new ones out
of the shattered pieces.
42
00:04:09,967 --> 00:04:13,233
Any species that wants
to survive long term on any
43
00:04:13,367 --> 00:04:16,734
possible world, will
have to learn how to engineer
44
00:04:16,867 --> 00:04:21,066
interplanetary and ultimately,
interstellar mass transit.
45
00:04:24,633 --> 00:04:27,066
How do we know this?
46
00:04:27,200 --> 00:04:30,100
The little we've learned
about the universe allows us
47
00:04:30,233 --> 00:04:32,433
glimpses of the future.
48
00:04:32,567 --> 00:04:35,200
I'm not talking about the
near-term where climate change
49
00:04:35,333 --> 00:04:39,266
caused by human activity poses
a danger to our civilization.
50
00:04:39,400 --> 00:04:42,567
If we want to
endure for thousands,
51
00:04:42,700 --> 00:04:45,900
millions even
billions of years,
52
00:04:46,033 --> 00:04:48,400
we'll have to stop dumping
all that carbon dioxide into
53
00:04:48,533 --> 00:04:51,700
the atmosphere, right now.
54
00:04:51,834 --> 00:04:53,967
But I'm gonna give us
the benefit of the doubt
55
00:04:54,100 --> 00:04:57,033
and take the long view.
56
00:04:59,600 --> 00:05:01,767
The sun is aging.
57
00:05:01,900 --> 00:05:04,033
Just like the rest of us.
58
00:05:04,166 --> 00:05:09,066
Someday, it will exhaust
the hydrogen fuel at its core.
59
00:05:15,800 --> 00:05:17,867
Five or six
billion years from now,
60
00:05:18,000 --> 00:05:22,367
the zone of hydrogen fusion
will slowly migrate outward,
61
00:05:22,500 --> 00:05:26,000
an expanding shell of
thermonuclear reactions.
62
00:05:26,133 --> 00:05:30,133
Until the temperatures
are less than about
10 million degrees.
63
00:05:38,433 --> 00:05:43,066
It will go from being a
yellow dwarf to a red giant.
64
00:05:43,934 --> 00:05:47,467
Its gravitational hold on
Venus and Earth will diminish
65
00:05:47,600 --> 00:05:50,967
allowing them to
migrate to a safer distance,
66
00:05:51,166 --> 00:05:53,967
for a little while.
67
00:05:54,100 --> 00:05:57,700
This red giant sun,
ruddy and bloated,
68
00:05:57,834 --> 00:06:01,066
will envelop and
devour the planet Mercury.
69
00:06:07,333 --> 00:06:10,467
The grace of the habitable
zone will be moving outward,
70
00:06:10,600 --> 00:06:13,500
farther and faster.
71
00:06:14,166 --> 00:06:17,567
By now, the intense light
and heat of the sun's expansion
72
00:06:17,700 --> 00:06:21,800
will reach all the way
out to the Jupiter system.
73
00:06:22,233 --> 00:06:24,533
Its clouds of ammonia
and water will escape and
74
00:06:24,667 --> 00:06:28,367
be lost to space as vapor.
75
00:06:30,367 --> 00:06:33,700
And for the first time,
the more dowdy, hidden layers
76
00:06:33,834 --> 00:06:39,033
down beneath Jupiter's
gaudy upper atmosphere
will be exposed.
77
00:06:43,867 --> 00:06:49,166
Could we make a home on
one of Jupiter's frozen moons?
78
00:06:49,734 --> 00:06:54,066
The thick layers
of ice encasing Europa
and Callisto will defrost,
79
00:06:54,200 --> 00:06:58,166
exposing the liquid oceans
beneath to harsh sunlight,
80
00:06:58,300 --> 00:07:01,834
thousands of times
stronger than before.
81
00:07:01,967 --> 00:07:06,033
This will liberate
large amounts of water vapor,
82
00:07:06,166 --> 00:07:09,600
starting a runaway
greenhouse effect.
83
00:07:10,633 --> 00:07:16,100
Ganymede's once
thin atmosphere will
become steamy and dense.
84
00:07:21,600 --> 00:07:24,467
If life was swimming
in those oceans all along,
85
00:07:24,600 --> 00:07:27,934
here's a new chance
to flourish and evolve.
86
00:07:28,066 --> 00:07:31,100
Then Ganymede will
belong to those beings.
87
00:07:31,233 --> 00:07:34,166
It's just as well, because
we'll want our next home
88
00:07:34,300 --> 00:07:38,200
to be at a safer
distance from the sun.
89
00:07:40,100 --> 00:07:42,467
Solar evolution is inevitable,
90
00:07:42,600 --> 00:07:45,667
but we have a billion
years to go house hunting.
91
00:07:45,800 --> 00:07:48,834
Plenty of time to seek
those worlds in the cosmos
92
00:07:48,967 --> 00:07:52,600
that could
become our new homes.
93
00:07:53,967 --> 00:07:58,367
Saturn, what has
the sun done to you?
94
00:07:58,500 --> 00:08:02,934
She's stolen your
glory, your rings.
95
00:08:05,200 --> 00:08:08,333
And Titan, she's robbed
you of your atmosphere.
96
00:08:12,767 --> 00:08:14,934
(thunder).
97
00:08:15,066 --> 00:08:16,367
Hey.
98
00:08:16,500 --> 00:08:19,533
We're running out of
possible worlds here.
99
00:08:23,700 --> 00:08:26,967
Just in time,
Neptune's moon, Triton,
100
00:08:27,100 --> 00:08:30,834
a world named for the son
of the Roman God, Neptune.
101
00:08:30,967 --> 00:08:35,133
First known to the Greeks
as Poseidon, the God of the Sea.
102
00:08:50,767 --> 00:08:54,900
No one's named this ocean yet,
it only began to exist when
103
00:08:55,033 --> 00:08:58,400
the heat of the red giant
sun melted the ammonia and
104
00:08:58,533 --> 00:09:02,533
water ices of this
once frigid moon.
105
00:09:02,667 --> 00:09:07,033
Our distant descendants
will live to different
rhythms than we do.
106
00:09:07,166 --> 00:09:11,900
A day on Triton
will be 144 hours long.
107
00:09:12,033 --> 00:09:13,667
And the winters
will be brutal.
108
00:09:13,800 --> 00:09:16,767
They'll be
nearly 50 years long.
109
00:09:16,900 --> 00:09:20,100
But still, the Triton of a
few billion years from now could
110
00:09:20,233 --> 00:09:22,433
be a great home for us.
111
00:09:22,567 --> 00:09:23,900
It's got everything,
112
00:09:24,033 --> 00:09:26,200
an atmosphere,
water oceans,
113
00:09:26,333 --> 00:09:29,734
the chemical building blocks
would make life possible.
114
00:09:29,867 --> 00:09:34,734
Okay, it's chilly,
but not much worse than
upstate New York in January.
115
00:09:34,867 --> 00:09:38,867
And that means, great
skiing all year round.
116
00:09:45,100 --> 00:09:49,033
But one day, the sun will
exhaust itself completely and
117
00:09:49,166 --> 00:09:53,800
the fleeting grace
of the habitable zone
will end here, too.
118
00:09:53,934 --> 00:09:56,800
When the sun's torrid
red giant phase is over,
119
00:09:56,934 --> 00:09:59,734
it will strip itself naked,
120
00:09:59,867 --> 00:10:03,400
revealing the small
white dwarf beneath.
121
00:10:04,033 --> 00:10:08,233
A star without even
enough energy left to warm
her surviving children.
122
00:10:09,266 --> 00:10:13,233
The moons of the
outer Solar System.
123
00:10:21,033 --> 00:10:24,400
So, if we're looking for
a long lease on a new home.
124
00:10:24,533 --> 00:10:27,467
Say, more than just a
couple hundred million years,
125
00:10:27,600 --> 00:10:30,600
we'd have to
travel even farther out.
126
00:10:30,734 --> 00:10:33,467
We'll have to leave our
Solar System and brave the
127
00:10:33,600 --> 00:10:36,934
vast bottomless ocean
of interstellar space.
128
00:10:37,066 --> 00:10:39,200
I know what you're thinking,
129
00:10:39,333 --> 00:10:42,533
"are we to venture
to the distant stars?"
130
00:10:42,667 --> 00:10:45,633
We once made a few baby
steps to the moon before we lost
131
00:10:45,767 --> 00:10:49,734
our will and scurried back
to the safety of our mother.
132
00:10:49,867 --> 00:10:54,400
What makes us think we
could survive a voyage
between the stars?
133
00:10:54,533 --> 00:10:59,066
The nearest of
which is 100 million times
farther than our moon.
134
00:10:59,200 --> 00:11:03,033
Wouldn't our tiny
ships be swallowed up
by the great unknown?
135
00:11:03,166 --> 00:11:05,400
I think we can do it.
136
00:11:05,533 --> 00:11:07,700
Why?
137
00:11:07,834 --> 00:11:10,567
Because we've done it before.
138
00:11:24,433 --> 00:11:28,133
TYSON: We dream of
sailing among the island
worlds of the Milky Way,
139
00:11:28,266 --> 00:11:31,300
catching photons with our sails.
140
00:11:31,433 --> 00:11:36,433
Daring to go tetherless
beyond the point of no return.
141
00:11:39,033 --> 00:11:41,934
We've passed this way before.
142
00:11:42,066 --> 00:11:45,667
Once, there was a people
who chose the unknown.
143
00:11:45,800 --> 00:11:49,600
They risked everything to
go forth on uncharted seas
144
00:11:49,734 --> 00:11:52,467
and their courage
was rewarded.
145
00:11:52,600 --> 00:11:55,533
They found paradise.
146
00:11:55,667 --> 00:11:59,200
I want to tell
you their story.
147
00:12:01,800 --> 00:12:06,867
(singing).
148
00:12:07,000 --> 00:12:09,000
We call these
people, the Lapita.
149
00:12:09,133 --> 00:12:11,166
But, that was
never their name.
150
00:12:11,300 --> 00:12:13,734
It was just the result
of a misunderstanding made
151
00:12:13,867 --> 00:12:16,633
decades ago when we
first began to discover the
152
00:12:16,767 --> 00:12:19,934
broken shards
of their pottery.
153
00:12:20,066 --> 00:12:24,934
To me, they're not the Lapita,
they are the Voyagers.
154
00:12:25,066 --> 00:12:28,433
A name far
more worthy of them.
155
00:12:30,133 --> 00:12:31,867
About 10,000 years ago,
156
00:12:32,000 --> 00:12:35,100
when the population
of settlements in Southern
China began to swell,
157
00:12:35,233 --> 00:12:39,033
there were those who
chose to pioneer the frontier,
158
00:12:39,166 --> 00:12:42,700
farther south to
what is now Taiwan.
159
00:12:45,033 --> 00:12:47,500
And our voyagers
settled there,
160
00:12:47,633 --> 00:12:49,767
happily for
thousands of years,
161
00:12:49,900 --> 00:12:54,400
until the place began
to get too crowded again.
162
00:12:55,934 --> 00:12:57,967
Just as we,
of this planet,
163
00:12:58,100 --> 00:13:01,166
came of age in a
kind of cosmic quarantine.
164
00:13:01,300 --> 00:13:03,433
Cut off from any
hope of knowing about,
165
00:13:03,567 --> 00:13:06,900
much less reaching the
other worlds of the cosmos.
166
00:13:07,033 --> 00:13:11,900
Our distant ancestors
were prisoners of the land.
167
00:13:13,033 --> 00:13:14,967
If you wanted to
travel a great distance,
168
00:13:15,100 --> 00:13:16,667
you had to walk there.
169
00:13:16,800 --> 00:13:18,734
And if you walked
as far as you could,
170
00:13:18,867 --> 00:13:21,467
you would be hemmed
in at the water's edge.
171
00:13:21,600 --> 00:13:25,100
This was before the age of the
great sea-faring civilizations.
172
00:13:25,233 --> 00:13:28,967
The Phoenicians of
the Middle-East and
the Minoans of Crete.
173
00:13:29,100 --> 00:13:32,734
And for most of their history,
they hugged the shore.
174
00:13:32,867 --> 00:13:37,567
Their fishing and trading
expeditions were careful
to keep land in sight.
175
00:13:42,467 --> 00:13:48,133
For our ancestors,
this was the edge
of the cosmic ocean.
176
00:13:51,633 --> 00:13:54,500
We do not know what first
inspired the voyagers to
177
00:13:54,633 --> 00:13:57,533
attempt the
seemingly impossible.
178
00:13:57,667 --> 00:14:00,500
Could they no
longer trust the Earth?
179
00:14:00,633 --> 00:14:03,934
(rumbling).
180
00:14:04,066 --> 00:14:07,000
They were living on a
tectonic plate where earthquakes
181
00:14:07,133 --> 00:14:10,000
and volcanic
eruptions were common.
182
00:14:10,133 --> 00:14:14,467
Or did hostile neighbors there
make life intolerable for them?
183
00:14:16,834 --> 00:14:20,433
Did a change in climate
threaten their livelihood?
184
00:14:21,433 --> 00:14:24,533
Were their new
population pressures?
185
00:14:24,667 --> 00:14:28,066
Did they begin to exhaust
the resources of their island
186
00:14:28,200 --> 00:14:32,000
by overhunting
and overfishing?
187
00:14:33,467 --> 00:14:36,834
Or was it simply something
innately human in them that
188
00:14:36,967 --> 00:14:40,200
made them want to
know what was out there?
189
00:14:40,333 --> 00:14:42,500
To reach for the
mysterious distance,
190
00:14:42,633 --> 00:14:45,800
no matter how
dangerous that might be?
191
00:14:45,934 --> 00:14:48,967
Whatever their
motives, over time,
192
00:14:49,100 --> 00:14:52,166
they conquered their fear.
193
00:14:52,300 --> 00:14:57,000
And made preparations
to venture where
no one had gone before.
194
00:14:58,033 --> 00:15:04,066
(speaking in native language).
195
00:15:14,567 --> 00:15:21,367
♪ ♪
196
00:15:25,233 --> 00:15:28,333
(clucking, oinking).
197
00:15:35,467 --> 00:15:38,300
(chirping).
198
00:15:42,533 --> 00:15:49,233
♪ ♪
199
00:16:14,633 --> 00:16:21,433
♪ ♪
200
00:16:41,033 --> 00:16:43,600
(chirping).
201
00:16:56,600 --> 00:17:02,667
(rain).
202
00:17:05,066 --> 00:17:10,000
(thunder).
203
00:17:15,033 --> 00:17:20,200
(waves crashing).
204
00:17:23,133 --> 00:17:29,934
♪ ♪
205
00:17:38,000 --> 00:17:40,967
(chirping).
206
00:18:23,667 --> 00:18:26,300
TYSON: The voyagers used the
careful observations of their
207
00:18:26,433 --> 00:18:30,000
ancestors over generations
to develop navigational
208
00:18:30,133 --> 00:18:33,934
techniques that
are still viable today.
209
00:18:34,066 --> 00:18:39,266
The seasonal migratory
flight patterns of
the birds was their GPS.
210
00:18:39,400 --> 00:18:41,834
They also brought high
flying frigatebirds with them,
211
00:18:41,967 --> 00:18:44,400
releasing them at the proper
time to find the shortest
212
00:18:44,533 --> 00:18:47,600
distance to the nearest land.
213
00:18:47,734 --> 00:18:50,000
They could read water,
feeling the ocean
currents in their
214
00:18:50,133 --> 00:18:54,066
fingertips and the
messages written in the clouds.
215
00:18:54,200 --> 00:18:59,834
These voyagers
were scientists and all of
nature was their laboratory.
216
00:19:06,667 --> 00:19:10,567
(speaking in native language).
217
00:19:26,333 --> 00:19:28,467
(shouts).
218
00:19:35,533 --> 00:19:41,967
♪ ♪
219
00:19:42,100 --> 00:19:46,333
TYSON: The Philippine Islands
was where they settled first.
220
00:19:49,266 --> 00:19:52,333
After lingering there
for 1,000 years,
221
00:19:52,467 --> 00:19:56,000
they were ready
to set sail again.
222
00:19:57,166 --> 00:19:59,867
New generations of
voyagers, Polynesians,
223
00:20:00,000 --> 00:20:03,900
mounted successful missions
of exploration to Indonesia.
224
00:20:04,033 --> 00:20:07,567
The Melanesian Islands, Vanuatu,
225
00:20:07,700 --> 00:20:13,300
Fiji, Samoa and
onto the Marquesas.
226
00:20:14,367 --> 00:20:18,233
And then, to the most
isolated island group on Earth,
227
00:20:18,367 --> 00:20:21,400
the Hawaiian Islands.
228
00:20:21,533 --> 00:20:28,166
Tahiti, Tonga, New Zealand,
Pitcairn and Easter Island.
229
00:20:29,300 --> 00:20:34,066
Their empire of water
covered nearly 20 million
square miles of sea.
230
00:20:34,200 --> 00:20:37,066
And they accomplished
this without a single nail
231
00:20:37,200 --> 00:20:40,033
or metal tool of any kind.
232
00:20:40,166 --> 00:20:42,900
As contact between the
islands became less frequent,
233
00:20:43,033 --> 00:20:46,033
the language the Polynesians
brought with them evolved into
234
00:20:46,166 --> 00:20:48,734
different tongues in isolation.
235
00:20:48,867 --> 00:20:51,967
Many words changed, but
one word remained the same
236
00:20:52,100 --> 00:20:57,533
in all the languages of
the wide pacific: "Lyar,"
237
00:20:57,667 --> 00:21:01,200
the world for "sail."
238
00:21:15,200 --> 00:21:21,800
♪ ♪
239
00:21:27,400 --> 00:21:30,867
Where are we bound for next?
240
00:21:32,367 --> 00:21:36,734
To that place where you
can read the book of worlds.
241
00:21:56,834 --> 00:21:59,834
TYSON: The ship of the
imagination is on a mission.
242
00:21:59,967 --> 00:22:02,734
Not to any particular world,
243
00:22:02,867 --> 00:22:06,967
but to an empty space
in the interstellar ocean.
244
00:22:07,600 --> 00:22:09,166
Why there?
245
00:22:09,300 --> 00:22:10,834
Come with me.
246
00:22:10,967 --> 00:22:15,000
We're headed to a place
50 billion miles from our sun.
247
00:22:15,133 --> 00:22:17,834
What I'm about to show
you is a gift of thousands
248
00:22:17,967 --> 00:22:20,300
of generations of searchers.
249
00:22:20,433 --> 00:22:25,166
We've been studying
light for millennia and
gravity for centuries.
250
00:22:25,300 --> 00:22:28,066
Among Einstein's many
insights was an understanding
251
00:22:28,200 --> 00:22:31,300
of how one could
affect the other.
252
00:22:31,433 --> 00:22:34,467
The way gravity bends
light makes it possible to turn
253
00:22:34,600 --> 00:22:36,800
any star,
including our own,
254
00:22:36,934 --> 00:22:40,500
into a kind of lens
for a cosmic telescope.
255
00:22:40,633 --> 00:22:43,500
One 50 billion miles long.
256
00:22:43,633 --> 00:22:46,867
Our most powerful space-based
telescopes of the present day
257
00:22:47,000 --> 00:22:51,200
can only see the worlds
of other suns as mere dots.
258
00:22:51,333 --> 00:22:55,133
A cosmic telescope could
give us detailed images of
259
00:22:55,266 --> 00:22:59,100
the mountains, oceans,
glaciers and who knows?
260
00:22:59,233 --> 00:23:02,633
Maybe even the
cities of these worlds.
261
00:23:09,300 --> 00:23:13,533
This is the cosmic
telescope's detector array.
262
00:23:13,667 --> 00:23:17,600
Collecting the light
bouncing off a distant world.
263
00:23:17,734 --> 00:23:22,333
It then sends a signal back
to Earth, becoming, in effect,
264
00:23:22,467 --> 00:23:26,233
the telescope's eye piece.
265
00:23:26,900 --> 00:23:29,400
See that brightest
star in the sky?
266
00:23:29,533 --> 00:23:31,533
That's our sun.
267
00:23:31,667 --> 00:23:35,100
And the lens
of this telescope.
268
00:23:35,233 --> 00:23:37,967
So, how can a star,
which you can't see through,
269
00:23:38,100 --> 00:23:41,667
be turned into a lens?
270
00:23:41,800 --> 00:23:44,567
When all the rays of light
from a distant planet pass
271
00:23:44,700 --> 00:23:47,600
very close to the sun,
the sun's gravity bends
272
00:23:47,734 --> 00:23:50,667
those rays ever so slightly.
273
00:23:50,800 --> 00:23:53,967
Where they converge in
space is called the focal point
274
00:23:54,100 --> 00:23:58,533
because that's where
the object you're looking
at comes into focus.
275
00:24:01,266 --> 00:24:05,834
So, what can you see through a
50 billion mile long telescope?
276
00:24:05,967 --> 00:24:09,100
Virtually anything you want.
277
00:24:09,233 --> 00:24:13,767
Galileo's best telescope
could magnify an image 30 times,
278
00:24:13,900 --> 00:24:16,700
making Jupiter, say,
appear 30 times closer.
279
00:24:16,834 --> 00:24:22,934
Our cosmic telescope
can make things appear
100 billion times closer.
280
00:24:23,066 --> 00:24:26,367
And we can aim it
at almost any direction.
281
00:24:26,500 --> 00:24:31,467
Our detector array moves
360 degrees around the sun.
282
00:24:31,600 --> 00:24:34,900
There's only one part of the
cosmos that's off-limits to us
283
00:24:35,033 --> 00:24:37,667
and that's the heart
of our own Milky Way Galaxy,
284
00:24:37,800 --> 00:24:39,633
which is just too bright.
285
00:24:39,767 --> 00:24:41,633
Its radiance is blinding.
286
00:24:41,767 --> 00:24:43,467
But with a
telescope like this one,
287
00:24:43,600 --> 00:24:46,000
so much else that has
been foreclosed to us,
288
00:24:46,133 --> 00:24:49,367
would be made visible.
289
00:24:54,367 --> 00:24:58,400
A possible world, perhaps.
290
00:24:58,533 --> 00:25:03,333
The mixture of gases
in its atmosphere can
tell us if life is there.
291
00:25:05,066 --> 00:25:07,767
Molecules have
specific color signatures.
292
00:25:07,900 --> 00:25:10,934
If we look at this atmosphere
through a spectroscope,
293
00:25:11,066 --> 00:25:14,934
an instrument that
breaks down light into
its constituent colors,
294
00:25:15,066 --> 00:25:19,133
we'll be able to identify
the molecules that
make up the atmosphere.
295
00:25:20,000 --> 00:25:24,367
The presence of
oxygen and methane are
tell-tale signs of life.
296
00:25:27,834 --> 00:25:31,433
This world is alive and
our cosmic telescope could
297
00:25:31,567 --> 00:25:35,066
give us a complete
picture of its entire surface.
298
00:25:38,233 --> 00:25:40,333
It's not just an
optical telescope,
299
00:25:40,467 --> 00:25:42,767
one that can only
see visible light.
300
00:25:42,900 --> 00:25:45,433
It's also a radio telescope.
301
00:25:45,567 --> 00:25:49,433
Just as it can magnify
light from distant
worlds 100 billion times,
302
00:25:49,567 --> 00:25:52,934
it can do the
same for radio waves.
303
00:25:53,066 --> 00:25:55,734
There is something
astronomers call a "water hole."
304
00:25:55,867 --> 00:25:58,066
It's named after that
place where the lions and
305
00:25:58,200 --> 00:26:00,934
the water buffalo
gather to drink and bathe.
306
00:26:01,066 --> 00:26:03,333
(radio static).
307
00:26:03,467 --> 00:26:05,467
It's a region of
the radio spectrum,
308
00:26:05,600 --> 00:26:08,533
where interference is at a
minimum and we can eavesdrop
309
00:26:08,667 --> 00:26:10,834
on even the faintest
transmissions between
310
00:26:10,967 --> 00:26:13,500
far-flung civilizations.
311
00:26:13,633 --> 00:26:16,633
We would need to use all of
our computing power to decrypt
312
00:26:16,767 --> 00:26:19,600
the signals hidden in the noise.
313
00:26:22,033 --> 00:26:26,400
(radio static).
314
00:26:26,533 --> 00:26:28,333
MAN (over radio): 1-4-1-5-9-2-.
315
00:26:28,467 --> 00:26:34,500
(radio chatter).
316
00:26:36,567 --> 00:26:42,800
TYSON: And this vast
telescope is also a means
for seeing back in time.
317
00:26:45,100 --> 00:26:49,000
You can't look across
space without seeing
an object in the past.
318
00:26:49,133 --> 00:26:52,900
That's because the
speed of light is finite.
319
00:26:53,033 --> 00:26:56,066
In the morning, look
up at the sun and see it as
320
00:26:56,200 --> 00:27:00,066
it was eight minutes
and 20 seconds ago.
321
00:27:00,200 --> 00:27:03,533
You'll never see
it any other way.
322
00:27:03,667 --> 00:27:06,266
That's because it takes
that long for light from the
323
00:27:06,400 --> 00:27:10,700
sun to travel the
93 million miles to Earth.
324
00:27:10,834 --> 00:27:13,600
And when we look at any
world through this telescope,
325
00:27:13,734 --> 00:27:17,300
we're seeing it in the past.
326
00:27:20,367 --> 00:27:24,400
Now, imagine the
cosmic telescope of
another civilization.
327
00:27:24,533 --> 00:27:28,500
Say, one that's 5,000
lightyears from Earth.
328
00:27:28,633 --> 00:27:31,533
The astronomers of that
world could witness the building
329
00:27:31,667 --> 00:27:33,700
of the pyramids in Egypt.
330
00:27:33,834 --> 00:27:38,600
Or follow the Polynesian
voyages as they bravely made
their way across the Pacific.
331
00:27:39,500 --> 00:27:43,000
But perhaps the most important
use of the cosmic telescope,
332
00:27:43,133 --> 00:27:46,333
would be our
search for new Earths.
333
00:27:46,467 --> 00:27:49,767
What I can't understand is,
why we haven't built one.
334
00:27:49,900 --> 00:27:52,800
We already know how to do it.
335
00:27:52,934 --> 00:27:55,967
We have the
technology right now.
336
00:28:00,767 --> 00:28:04,033
When would you like
the future to begin?
337
00:28:21,400 --> 00:28:23,033
TYSON: Okay.
338
00:28:23,166 --> 00:28:26,400
We've got the biggest
dreams of putting our
eyes on other worlds.
339
00:28:26,533 --> 00:28:29,767
Traveling to them,
making them our home.
340
00:28:29,900 --> 00:28:32,233
But, how do we get there?
341
00:28:32,367 --> 00:28:34,633
The stars are so far apart.
342
00:28:34,767 --> 00:28:37,967
We would need sailing ships
that could sustain human crews
343
00:28:38,100 --> 00:28:41,033
over the longest
haul of all time.
344
00:28:41,166 --> 00:28:44,600
The nearest star is
four lightyears away.
345
00:28:44,734 --> 00:28:49,400
That's 24 trillion
miles to Proxima Centuri.
346
00:28:55,066 --> 00:28:58,266
Just to give you some idea
of how far away that point
347
00:28:58,400 --> 00:29:00,400
of light really is?
348
00:29:00,533 --> 00:29:02,767
If NASA's Voyager
One spacecraft,
349
00:29:02,900 --> 00:29:04,700
which moves at
a pretty good clip,
350
00:29:04,834 --> 00:29:06,667
38,000 miles an hour,
351
00:29:06,800 --> 00:29:09,100
was headed for
Proxima Centuri?
352
00:29:09,233 --> 00:29:12,734
It would take
70,000 years to get there.
353
00:29:12,867 --> 00:29:15,500
And that's only
the nearest star out of
354
00:29:15,633 --> 00:29:19,934
the hundreds of billions
in our galaxy alone.
355
00:29:29,667 --> 00:29:33,233
So, if we want to endure as
a species beyond the projected
356
00:29:33,367 --> 00:29:35,400
shelf life of our own planet,
357
00:29:35,533 --> 00:29:38,567
we'd better act
like the Polynesians.
358
00:29:38,700 --> 00:29:41,834
We need to take what we know
of nature and build sailing
359
00:29:41,967 --> 00:29:48,000
ships that can ride the light
as they once rode the wind.
360
00:29:52,967 --> 00:29:56,200
These sails are
enormous, miles high,
361
00:29:56,333 --> 00:29:58,100
but they're very thin.
362
00:29:58,233 --> 00:30:01,533
1,000 times thinner
than a garbage bag.
363
00:30:08,800 --> 00:30:15,600
♪ ♪
364
00:30:17,333 --> 00:30:21,066
When a photon of light
strikes those magnificent sails
365
00:30:21,200 --> 00:30:23,300
it gives them a little push.
366
00:30:26,967 --> 00:30:33,767
♪ ♪
367
00:30:34,400 --> 00:30:36,867
This means then,
in the vacuum of space,
368
00:30:37,000 --> 00:30:41,600
even the tiniest
push from a photon will
propel them ever faster,
369
00:30:41,734 --> 00:30:46,300
until they're moving at
a significant fraction
of the speed of light.
370
00:30:53,600 --> 00:30:56,300
When you get too far from your
star and the light dwindles,
371
00:30:56,433 --> 00:31:00,367
lasers can do the trick.
372
00:31:05,934 --> 00:31:12,667
♪ ♪
373
00:31:18,300 --> 00:31:21,934
If we were to light-sail
our way to Proxima Centuri,
374
00:31:22,066 --> 00:31:24,233
it wouldn't take 70,000 years.
375
00:31:24,367 --> 00:31:28,166
But only 20 years.
376
00:31:33,800 --> 00:31:37,600
Proxima B lies in the
habitable zone of its star.
377
00:31:37,734 --> 00:31:41,400
But we don't yet know
if it could support life.
378
00:31:41,533 --> 00:31:43,900
Does it have the kind of
protective magnetic field that
379
00:31:44,033 --> 00:31:48,667
has sheltered the
evolution of life on the
surface of our world?
380
00:31:51,100 --> 00:31:53,767
Another consequence
of Proxima B's
close location to its
381
00:31:53,900 --> 00:31:58,367
star is that the planet
is probably tidily locked.
382
00:31:59,467 --> 00:32:02,533
One side
perpetually facing the star.
383
00:32:02,667 --> 00:32:06,200
The other?
Doomed to endless night.
384
00:32:14,333 --> 00:32:21,066
♪ ♪
385
00:32:21,967 --> 00:32:26,200
(rumbling).
386
00:32:26,333 --> 00:32:28,700
These little
stars may be lukewarm,
387
00:32:28,834 --> 00:32:31,667
but they have a long
future ahead of them.
388
00:32:31,800 --> 00:32:34,033
Trillions of years.
389
00:32:34,166 --> 00:32:36,700
Think of the continuity
and growth potential of
390
00:32:36,834 --> 00:32:42,033
a civilization with a future
measured in trillions of years?
391
00:32:43,400 --> 00:32:46,166
It's always magic hour on
this strip of land that lies
392
00:32:46,300 --> 00:32:50,667
between day and
night of this world.
393
00:32:50,800 --> 00:32:54,066
If Proxima B is habitable,
its life would be confined
394
00:32:54,200 --> 00:32:56,600
to this twilight zone.
395
00:32:56,734 --> 00:32:59,400
It could be a home for
the indigenous life here or
396
00:32:59,533 --> 00:33:04,133
a possible campsite
for our descendants.
397
00:33:05,467 --> 00:33:10,400
The gravity on Proxima
B is about 10% greater
than ours on Earth.
398
00:33:11,166 --> 00:33:13,233
No real problem for us.
399
00:33:13,367 --> 00:33:16,800
Just a little like
exercising with weights on.
400
00:33:19,633 --> 00:33:22,667
Remote scanning from orbit
found no apparent signs of
401
00:33:22,800 --> 00:33:27,433
life making Proxima B a
waystation on a much grander
402
00:33:27,567 --> 00:33:31,166
interstellar
diaspora of Earthlings.
403
00:33:31,300 --> 00:33:34,467
But for those longer trips?
404
00:33:34,600 --> 00:33:38,200
We're gonna
need a faster boat.
405
00:33:39,200 --> 00:33:43,200
Let's say we found
a system located 100
light-years from home.
406
00:33:43,333 --> 00:33:46,667
One with several
potentially habitable worlds.
407
00:33:46,800 --> 00:33:51,300
For light-sailors, that
would be a 500 year long trip.
408
00:33:51,433 --> 00:33:55,367
Is it possible to build
a ship that could break
the cosmic speed limit?
409
00:33:56,433 --> 00:34:00,433
A mathematical physicist,
Miguel Alcubierre of Mexico,
410
00:34:00,567 --> 00:34:03,867
inspired by the original
Star Trek television series,
411
00:34:04,000 --> 00:34:06,734
conceived the calculations
for a ship that could
412
00:34:06,867 --> 00:34:10,500
theoretically travel
faster than the speed of light.
413
00:34:10,633 --> 00:34:13,834
If successful, it could
cut the travel time between
414
00:34:13,967 --> 00:34:19,033
our sun and this distant
star system down to a
single year or even less.
415
00:34:19,934 --> 00:34:23,200
But wait a minute, isn't
it a cardinal rule of science
416
00:34:23,333 --> 00:34:26,734
that "thou shalt not
travel faster than light?"
417
00:34:26,867 --> 00:34:28,333
It is.
418
00:34:28,467 --> 00:34:31,467
But here's the thing
about the Alcubierre Drive.
419
00:34:31,600 --> 00:34:35,600
It doesn't move,
the cosmos does.
420
00:34:35,734 --> 00:34:39,767
The ship itself
would be enclosed in
its own space-time bubble.
421
00:34:39,900 --> 00:34:42,734
Where it needn't
violate any laws of physics.
422
00:34:42,867 --> 00:34:46,333
Harold White of
the United States ironed
out some of the kinks.
423
00:34:46,467 --> 00:34:51,166
Such as prohibitively enormous
energy requirements to fly it.
424
00:34:52,367 --> 00:34:56,934
But it remains far
beyond our immediate grasp.
425
00:34:58,200 --> 00:35:01,200
The Alcubierre Drive Ship
is a gravitational wave making
426
00:35:01,333 --> 00:35:04,300
machine, that compresses
the ocean of space-time
427
00:35:04,433 --> 00:35:08,667
in front of it and expands
that ocean in its wake.
428
00:35:08,800 --> 00:35:13,767
Jet skis for joyriding
through the galaxy and beyond.
429
00:35:14,500 --> 00:35:16,200
Who knows?
430
00:35:16,333 --> 00:35:20,867
Maybe the entire
Laniakea supercluster could
one day become our pond.
431
00:35:21,000 --> 00:35:24,200
That's 100,000 galaxies.
432
00:35:24,333 --> 00:35:30,467
Laniakea, the
phrase in Hawaiian for
"immeasurable heaven."
433
00:35:31,967 --> 00:35:34,200
An advanced version
of our Alcubierre Drive
434
00:35:34,333 --> 00:35:39,500
could do 600 trillion
miles in the blink of an eye.
435
00:35:42,967 --> 00:35:47,900
Before you know it,
you're in the planetary
system of a distant star.
436
00:35:48,033 --> 00:35:51,066
Let's call it,
the "Hoku" system.
437
00:35:51,200 --> 00:35:56,367
A red dwarf star surrounded
by a retinue of rocky
and ice giant planets.
438
00:35:56,500 --> 00:36:00,400
Somewhere among them is a world
that we have come to call home.
439
00:36:00,533 --> 00:36:04,367
Our cosmic telescope sifted
through all the stars within
440
00:36:04,500 --> 00:36:09,367
a radius of 100 light years and
pointed the way to this one.
441
00:36:09,500 --> 00:36:12,767
All seven of these planets,
huddle closer to their star
442
00:36:12,900 --> 00:36:16,567
than Mercury does to our sun.
443
00:36:19,166 --> 00:36:23,600
Haumia is just
on the outskirts of
Hoku's habitable zone.
444
00:36:23,734 --> 00:36:26,767
Those warm green
colors seem inviting,
445
00:36:26,900 --> 00:36:29,600
but we're not seeing
the tops of forests.
446
00:36:29,734 --> 00:36:32,934
That green comes
from methane and ammonia.
447
00:36:33,066 --> 00:36:35,934
Even at a distance
of only 27 million miles,
448
00:36:36,066 --> 00:36:40,133
the star Hoku is too
weak to keep this planet warm.
449
00:36:43,100 --> 00:36:47,700
We are now in the sweet
spot of Hoku's habitable zone.
450
00:36:49,367 --> 00:36:52,433
And this is the
planet Tangaroa,
451
00:36:52,567 --> 00:36:56,800
where the latest
chapter of the saga of
our species is playing out.
452
00:37:03,166 --> 00:37:08,200
It took a few hundred years
for humans to terraform
this lifeless world.
453
00:37:08,333 --> 00:37:13,100
But now, even the air
tastes as sweet as home.
454
00:37:19,633 --> 00:37:22,967
But this was only Indonesia.
455
00:37:23,100 --> 00:37:25,834
One of the earlier stops on
our nomadic odyssey throughout
456
00:37:25,967 --> 00:37:27,667
the Milky Way.
457
00:37:27,800 --> 00:37:31,667
There were still so
many islands that lay ahead.
458
00:37:38,233 --> 00:37:41,500
And in this
dream future of ours,
459
00:37:41,633 --> 00:37:44,300
with our faster
than light craft?
460
00:37:44,433 --> 00:37:47,633
There would come a
time when we could place
our cosmic telescope
461
00:37:47,767 --> 00:37:52,200
far enough away from our
home planet to see first-hand,
462
00:37:52,333 --> 00:37:58,500
those of our nameless
ancestors who first
set sail on unknown seas.
463
00:38:13,700 --> 00:38:18,533
(radio static).
464
00:38:32,166 --> 00:38:36,934
TYSON: Carl Sagan made this
drawing when he was a child.
465
00:38:37,066 --> 00:38:41,300
Imagining the unfolding of the
next Golden Age of Exploration.
466
00:38:50,633 --> 00:38:54,600
As a scientist, he
played a central role in it.
467
00:38:54,734 --> 00:38:58,500
And now, he speaks
to us out of the past.
468
00:38:58,633 --> 00:39:02,333
About our
dreams of the future.
469
00:39:05,367 --> 00:39:08,300
SAGAN: Are we to
venture out into space?
470
00:39:08,433 --> 00:39:11,333
Move worlds,
re-engineer planets,
471
00:39:11,467 --> 00:39:14,667
spread to
neighboring star systems?
472
00:39:14,800 --> 00:39:18,266
We, who cannot even put
our own planetary home in order,
473
00:39:18,400 --> 00:39:21,633
riven with
rivalries and hatreds.
474
00:39:21,767 --> 00:39:24,633
Despoiling our environment,
murdering one another through
475
00:39:24,767 --> 00:39:27,533
irritation and inattention.
476
00:39:27,667 --> 00:39:31,600
As well as on deadly purpose
and moreover, a species that,
477
00:39:31,734 --> 00:39:35,000
until only recently,
was convinced that the whole
478
00:39:35,133 --> 00:39:37,233
universe was made
for its sole benefit.
479
00:39:40,600 --> 00:39:44,600
I do not imagine that
it is precisely 'we.'
480
00:39:44,734 --> 00:39:49,734
With our present customs
and social conventions
who will be out there.
481
00:39:51,100 --> 00:39:54,266
If we continue to accumulate
only power and not wisdom,
482
00:39:54,400 --> 00:39:56,467
we will surely
destroy ourselves.
483
00:39:58,767 --> 00:40:03,633
Our very existence in
that distant time requires
484
00:40:03,767 --> 00:40:08,533
that we will have changed
our institutions and ourselves.
485
00:40:10,834 --> 00:40:15,333
How can I dare to guess
about humans in the far future?
486
00:40:15,467 --> 00:40:19,300
It is, I think, only a
matter of natural selection.
487
00:40:19,433 --> 00:40:24,500
If we become even slightly
more violent, short-sighted,
488
00:40:24,633 --> 00:40:27,900
ignorant and
selfish than we are now.
489
00:40:28,033 --> 00:40:31,900
Almost certainly,
we will have no future.
490
00:40:34,100 --> 00:40:38,166
If you're young, it's
just possible that we will
491
00:40:38,300 --> 00:40:41,333
be taking our first steps
on near-Earth asteroids and
492
00:40:41,467 --> 00:40:44,934
Mars during your lifetime.
493
00:40:45,066 --> 00:40:48,800
By the time we're ready to
settle even the nearest other
494
00:40:48,934 --> 00:40:53,200
planetary systems,
we will have changed.
495
00:40:53,333 --> 00:40:57,233
The simple passage of
so many generations
will have changed us.
496
00:40:57,367 --> 00:41:01,333
The different circumstances
we will be living under
will have changed us.
497
00:41:02,767 --> 00:41:07,467
We're an adaptable species.
498
00:41:13,033 --> 00:41:16,333
It will not be we
who reach Alpha Centauri
499
00:41:16,467 --> 00:41:18,500
and the other nearby stars.
500
00:41:18,633 --> 00:41:21,467
It will be a
species very like us,
501
00:41:21,600 --> 00:41:26,500
but with more
of our strengths and
fewer of our weaknesses.
502
00:41:30,934 --> 00:41:33,667
A species
returned to circumstances,
503
00:41:33,800 --> 00:41:37,734
more like those for which
it was originally evolved.
504
00:41:38,400 --> 00:41:43,533
More confident, far-seeing,
capable and prudent.
505
00:41:44,700 --> 00:41:47,633
The sorts of beings
we would want to represent us
506
00:41:47,767 --> 00:41:51,200
in a universe that,
for all we know,
507
00:41:51,333 --> 00:41:54,467
is filled with
species much older,
508
00:41:54,600 --> 00:41:58,066
much more powerful
and very different.
509
00:42:05,266 --> 00:42:10,567
The vast distances that separate
the stars are providential.
510
00:42:12,033 --> 00:42:17,033
Beings and worlds are
quarantined one from another.
511
00:42:18,667 --> 00:42:22,233
The quarantine is lifted,
only for those with sufficient
512
00:42:22,367 --> 00:42:28,834
self-knowledge and
judgement to have safely
traveled from star to star.
513
00:42:30,533 --> 00:42:36,834
♪ ♪
514
00:42:40,400 --> 00:42:44,600
Our remote descendants safely
arrayed on many worlds through
515
00:42:44,734 --> 00:42:49,633
the solar system and
beyond will be unified by
516
00:42:49,767 --> 00:42:54,367
their common heritage,
by their regard for their
517
00:42:54,500 --> 00:43:00,767
home planet and by the
knowledge that whatever
other life may be,
518
00:43:00,900 --> 00:43:04,900
the only humans in all
the universe come from Earth.
519
00:43:05,433 --> 00:43:12,133
("Thank you, mother"
in native languages).
520
00:43:12,433 --> 00:43:15,166
MAN: Thank you, mother.
521
00:43:51,633 --> 00:43:53,600
Captioned by
Cotter Captioning Services.