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00:00:07,680 --> 00:00:10,280
[calm music playing]
2
00:00:10,360 --> 00:00:13,960
[chimpanzees screeching]
3
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[chimpanzees hooting]
4
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[clock ticks]
5
00:00:29,520 --> 00:00:31,480
[Freeman] It's morning in the forest.
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And for this troop of chimpanzees,
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it's time to get out of bed
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and get on with the day.
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[intriguing music playing]
10
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[chimpanzees screeching]
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00:00:45,960 --> 00:00:49,640
[Freeman] But when you sleep
in a nest 40 meters up in the air,
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00:00:51,080 --> 00:00:53,320
it can be a bit of a challenge.
13
00:00:58,240 --> 00:00:59,960
[playful music playing]
14
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[chimpanzee howling]
15
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[chirping]
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[Freeman] This morning ritual
has been playing out like clockwork
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for countless generations.
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[pensive music playing]
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A rhythm driven by one of the most
mysterious properties of our universe.
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Time.
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And time is playing
an extra important role
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for one female chimp.
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Celeste is in her mid-30s,
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and she has a ticking clock inside her.
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[whooshing]
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A clock that was set
13.8 billion years ago.
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[heart thumping]
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[fizzling, whooshing]
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From The Big Bang came atoms…
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[zapping]
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…and energy…
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[rumbling]
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…which have journeyed across
vast reaches of space.
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[dramatic music playing]
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And these ingredients
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are now assembling…
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to create a new life.
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In Celeste's womb,
a tiny chimpanzee is forming.
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[heartbeat thumping softly]
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It will be another 150 days
before this baby meets the world.
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That's the time it takes.
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And without time,
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nothing in our universe
would ever be born.
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[heartbeat continues thumping]
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From the youngest chimpanzee…
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to the oldest black hole.
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[fizzling]
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[whooshing]
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00:03:23,680 --> 00:03:27,280
But how did time start in the first place?
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Does everything experience time
in the same way?
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00:03:35,000 --> 00:03:38,440
And will our universe's clock
ever stop ticking?
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[dramatic music playing]
53
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[clock ticking]
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[chimpanzees hooting]
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00:04:09,440 --> 00:04:12,960
[Freeman] The day begins for a chimp
much as it does for us.
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Breakfast.
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[pensive music playing]
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A critical meal…
when you're eating for two.
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Celeste is already an experienced mom.
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Her firstborn, Apollo,
is the dominant male of the troop.
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And he can be a bit slow
to get going in the morning.
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Each chimp is a different age.
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Each has a distinct personality.
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But all of them are creatures of routine.
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Their lives governed
by the passage of time.
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[ethereal music playing]
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We can't see it.
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-[animals growling]
-Or hear it.
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-[chimpanzee screeches]
-We can't influence it in any way.
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[elephant growls]
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And yet, every heartbeat,
every choice and action,
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every inaction is a consequence
of time's continuous flow.
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[whooshing]
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It can whiz by or drag on.
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But time ticks ever onward.
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Stars and planets form, age, and die.
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[dramatic music playing]
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In their wake, new stars emerge.
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And from a rare few,
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the most mysterious objects
in the universe are born.
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Black holes.
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[fizzling]
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[whooshing]
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Time is the cosmic conductor.
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[clock ticking]
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Nothing can escape its grasp.
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[dramatic vocal music playing]
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[clock ticks]
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[birds chirping]
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[chimpanzee hooting]
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Although we have devices
that can track and measure time…
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[dramatic music playing]
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…chimps don't.
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Celeste and her family
use the sun as their guide.
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Rising and arcing across the sky.
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[hooting]
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As it moves…
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so do they.
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[chimpanzee screeching]
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Chimps rarely sleep
in the same nest twice.
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Each morning,
they head off in search of fresh fruit.
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Journeying from one part
of their territory to another.
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But right now, the ripest fruit…
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is on the other side of an open plain.
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[ominous music playing]
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Apollo and the strongest members
of the troop go ahead
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to make sure it's safe for the others.
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Out in the open,
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they're vulnerable
to predators, rival chimps,
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and the heat of the rising sun.
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They need to be quick.
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Time is ticking.
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[suspenseful music playing]
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The sun traveling across the sky
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forms the chimps' basic unit of time.
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From sunrise to sunset
and back to sunrise.
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The 24-hour day.
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But a day
is not actually a measure of time at all.
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It's a measure of motion.
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00:09:08,640 --> 00:09:11,480
As our planet rotates on its axis,
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the forest moves through space
at 1,600 kilometers per hour.
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It takes 24 hours
for Earth to do one full turn.
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Giving the chimps 24 hours of movement,
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12 in sunshine and 12 in darkness.
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[dramatic music playing]
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Again and again.
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[clock ticking]
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It's our planet's steady spin
that sets Earth's master clock.
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00:09:55,040 --> 00:09:58,200
And is the chimps' trusted timekeeper.
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00:10:02,480 --> 00:10:05,080
But this essential cycle
we take for granted…
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00:10:07,320 --> 00:10:08,840
is not universal.
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00:10:10,000 --> 00:10:10,880
[clock ticks]
133
00:10:10,960 --> 00:10:12,480
[ominous music playing]
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00:10:14,000 --> 00:10:14,880
[clock ticks]
135
00:10:15,840 --> 00:10:18,480
As soon as you leave our home planet…
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[clock ticks]
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00:10:20,280 --> 00:10:22,960
…the 24-hour day no longer applies.
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00:10:27,960 --> 00:10:29,840
Flying closest to the sun…
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00:10:30,600 --> 00:10:32,000
[rumbling, whooshing]
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00:10:32,080 --> 00:10:33,520
…is the planet Mercury.
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00:10:35,160 --> 00:10:39,000
Compared to us,
it rotates at a snail's pace.
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00:10:44,520 --> 00:10:49,760
Our neighbor Venus spins even slower.
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00:10:49,840 --> 00:10:51,320
[intense music playing]
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00:10:51,400 --> 00:10:54,200
It takes longer to rotate on its axis
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00:10:55,520 --> 00:10:57,760
than it does to orbit the sun.
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00:11:00,920 --> 00:11:06,040
Making Venus's day longer than its year.
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00:11:09,680 --> 00:11:12,640
Each planet has its own unique day length.
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00:11:14,480 --> 00:11:15,440
[whooshing]
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00:11:15,520 --> 00:11:17,800
[intense music continues]
150
00:11:19,560 --> 00:11:21,440
[whooshing]
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00:11:25,680 --> 00:11:27,080
[whooshing]
152
00:11:30,600 --> 00:11:31,800
[whooshing]
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00:11:32,320 --> 00:11:36,040
Including planets
far beyond our solar system.
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00:11:36,120 --> 00:11:38,320
[whooshing]
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00:11:40,360 --> 00:11:42,440
Sixty-three light years away,
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00:11:43,520 --> 00:11:45,280
orbiting a young star,
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00:11:46,360 --> 00:11:48,640
is Beta Pictoris b.
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00:11:52,520 --> 00:11:55,240
It spins so fast…
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00:11:56,080 --> 00:11:57,400
[whooshing rapidly]
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00:11:57,480 --> 00:11:58,640
[rumbling]
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00:11:58,720 --> 00:12:01,000
…it bulges out at the sides.
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00:12:04,720 --> 00:12:08,160
It is the fastest-spinning world
we know of.
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00:12:09,040 --> 00:12:10,120
[intense music playing]
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00:12:10,200 --> 00:12:13,120
Here, a day lasts just eight hours.
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00:12:13,200 --> 00:12:14,080
[clock ticks]
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00:12:18,480 --> 00:12:23,120
Every planet in our universe spins
at its own speed.
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00:12:23,200 --> 00:12:25,680
[whooshing]
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00:12:26,360 --> 00:12:27,760
Billions of worlds,
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00:12:28,880 --> 00:12:30,440
each with their own clock,
170
00:12:31,760 --> 00:12:33,800
ticking away to different rhythms.
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00:12:33,880 --> 00:12:35,280
[multiple clocks ticking]
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00:12:35,360 --> 00:12:40,880
But all moving forward
on a universal cosmic timeline.
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00:12:43,720 --> 00:12:46,280
[single clock ticking]
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00:12:49,080 --> 00:12:51,680
[calm music playing]
175
00:12:52,320 --> 00:12:53,440
[clock ticks]
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00:12:55,960 --> 00:12:58,480
[chimpanzees screeching]
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00:12:58,560 --> 00:12:59,640
Back on Earth,
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00:13:00,640 --> 00:13:03,120
with the sun now almost directly overhead,
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00:13:05,080 --> 00:13:07,560
the chimps know exactly what time it is.
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00:13:17,160 --> 00:13:18,360
It's lunchtime.
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00:13:20,720 --> 00:13:22,760
[calm music continues]
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00:13:31,160 --> 00:13:35,760
And their crossing of the savanna
has been timed to perfection.
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00:13:36,720 --> 00:13:40,200
[howling]
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00:13:42,680 --> 00:13:44,400
They've hit the jackpot.
185
00:13:51,760 --> 00:13:54,680
These sweet berries
of the African grape tree
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00:13:56,400 --> 00:13:58,560
are only around for a few weeks.
187
00:14:05,080 --> 00:14:08,600
A rare seasonal gift from the forest.
188
00:14:12,680 --> 00:14:16,280
Where the middle of the day
is a very productive time.
189
00:14:18,320 --> 00:14:20,200
[dramatic music playing]
190
00:14:20,840 --> 00:14:24,640
Animals of all sizes
are tending to their daily tasks.
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00:14:30,000 --> 00:14:32,880
And each experiences time differently.
192
00:14:37,120 --> 00:14:40,800
For small creatures
that live fast, short lives…
193
00:14:41,480 --> 00:14:44,520
[dramatic music intensifies]
194
00:14:45,600 --> 00:14:48,960
…lunchtime can feel like a lifetime.
195
00:14:53,720 --> 00:14:54,600
[elephant snorts]
196
00:14:54,680 --> 00:14:57,440
For slower, longer living things,
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00:14:58,120 --> 00:15:01,280
an hour can go by in the blink of an eye.
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00:15:03,280 --> 00:15:05,680
[dramatic music continues]
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00:15:08,320 --> 00:15:11,360
But whether you're living in high speed
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00:15:12,360 --> 00:15:14,120
or in slow motion,
201
00:15:15,960 --> 00:15:21,000
all life in the forest must adhere
to the same 24-hour day.
202
00:15:23,720 --> 00:15:25,920
And as the world keeps spinning…
203
00:15:26,800 --> 00:15:29,320
[dramatic music crescendos]
204
00:15:29,400 --> 00:15:31,560
…those days keep ticking by…
205
00:15:33,600 --> 00:15:37,720
dictating the lives of every chimpanzee.
206
00:15:41,440 --> 00:15:42,760
One in particular.
207
00:15:43,520 --> 00:15:46,280
[low rumbling]
208
00:15:49,960 --> 00:15:51,920
At just 15 weeks,
209
00:15:52,880 --> 00:15:56,960
this baby's entire body
could fit in its mother's hand.
210
00:16:00,560 --> 00:16:02,440
For it to fully form,
211
00:16:02,520 --> 00:16:05,760
a cascade
of perfectly timed events must occur.
212
00:16:08,160 --> 00:16:10,360
For the next 130 days,
213
00:16:11,120 --> 00:16:15,480
every minute,
every nanosecond is critical.
214
00:16:16,240 --> 00:16:18,680
[dramatic music playing]
215
00:16:22,200 --> 00:16:24,120
[ethereal tinkling]
216
00:16:24,200 --> 00:16:30,160
New cells divide and grow
with remarkable speed and precision.
217
00:16:34,200 --> 00:16:35,200
Right now,
218
00:16:36,160 --> 00:16:41,680
brain cells are multiplying
at a rate of around 15 million per hour.
219
00:16:51,760 --> 00:16:54,800
All of us, from our very first moments,
220
00:16:55,800 --> 00:17:00,160
have a deep biological relationship
with time.
221
00:17:00,240 --> 00:17:02,680
[dramatic music continues]
222
00:17:07,800 --> 00:17:10,400
[chimpanzees hooting]
223
00:17:13,000 --> 00:17:14,040
[clock ticks]
224
00:17:15,680 --> 00:17:17,280
[calm music playing]
225
00:17:17,360 --> 00:17:19,120
As the sunlight wanes,
226
00:17:21,760 --> 00:17:24,280
the chimps instinctively switch gears.
227
00:17:27,840 --> 00:17:29,080
To evening mode.
228
00:17:29,160 --> 00:17:30,240
[chimpanzee yawning]
229
00:17:39,120 --> 00:17:41,920
Nesting calls signal to the whole troop.
230
00:17:42,000 --> 00:17:43,520
[chimpanzees hooting]
231
00:17:44,400 --> 00:17:47,560
It's time to find a safe place
to spend the night.
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00:17:47,640 --> 00:17:50,080
[playful music playing]
233
00:18:01,400 --> 00:18:05,560
Their bedding needs to be soft but strong.
234
00:18:12,200 --> 00:18:14,640
It doesn't hurt if it tastes good either.
235
00:18:18,880 --> 00:18:21,800
The rhythm of every day in the forest
236
00:18:21,880 --> 00:18:25,360
is determined by the sun's position
in the sky.
237
00:18:26,960 --> 00:18:30,080
[pensive music playing]
238
00:18:34,560 --> 00:18:37,000
But the chimp's innate sense of time
239
00:18:38,200 --> 00:18:40,920
comes from something inside them.
240
00:18:41,000 --> 00:18:44,000
[chimpanzees screeching]
241
00:18:45,120 --> 00:18:47,200
[whooshing]
242
00:18:49,680 --> 00:18:53,680
Deep in their brains
is a biological clock.
243
00:18:56,560 --> 00:18:59,520
Bundles of neurons act as a pendulum…
244
00:18:59,600 --> 00:19:01,760
[whooshing]
245
00:19:01,840 --> 00:19:06,400
…controlled by genes
that switch on and off…
246
00:19:08,520 --> 00:19:12,960
and a cycle that repeats every 24 hours.
247
00:19:13,480 --> 00:19:16,160
[whooshing continues]
248
00:19:16,240 --> 00:19:21,320
These clock genes create
a circadian rhythm in the body
249
00:19:22,080 --> 00:19:28,200
that waxes and wanes in sync
with our planet's rotation.
250
00:19:30,600 --> 00:19:32,040
Controlling hormones…
251
00:19:34,680 --> 00:19:36,440
[chimpanzee screeching]
252
00:19:36,520 --> 00:19:37,440
…heart rates,
253
00:19:38,800 --> 00:19:40,640
and energy levels.
254
00:19:46,200 --> 00:19:50,760
And right now, the chimps' body clocks
are sending the message,
255
00:19:52,160 --> 00:19:54,720
"It's time to get sleepy."
256
00:19:55,640 --> 00:19:56,640
[moans]
257
00:19:57,960 --> 00:19:59,560
Not everyone can though.
258
00:20:01,880 --> 00:20:04,280
[heartbeat thumping softly]
259
00:20:14,320 --> 00:20:17,240
Celeste's baby's brain is still forming.
260
00:20:20,640 --> 00:20:23,000
With no internal clock of its own,
261
00:20:23,640 --> 00:20:27,240
it relies on its mother's hormones
to keep it synchronized.
262
00:20:29,600 --> 00:20:33,360
But baby doesn't always get the memo.
263
00:20:37,480 --> 00:20:39,120
Lucky for Celeste,
264
00:20:39,200 --> 00:20:41,560
with so much growing to do,
265
00:20:41,640 --> 00:20:44,520
her baby does eventually drift off.
266
00:20:47,000 --> 00:20:48,640
[insects chirping]
267
00:20:48,720 --> 00:20:50,920
[pensive music playing]
268
00:20:59,600 --> 00:21:03,520
While the chimps go to sleep
high in the treetops…
269
00:21:07,280 --> 00:21:10,680
other forest dwellers are just waking up.
270
00:21:22,720 --> 00:21:25,400
Body clocks tick away
271
00:21:25,480 --> 00:21:29,760
in the cells of plants and animals
throughout the forest.
272
00:21:32,600 --> 00:21:34,080
[bat chittering]
273
00:21:38,320 --> 00:21:43,520
Clock genes evolved
two and a half billion years ago
274
00:21:43,600 --> 00:21:45,600
in the first living cells.
275
00:21:48,080 --> 00:21:52,880
Those that could anticipate the light
and dark of a day had an advantage.
276
00:21:56,160 --> 00:21:57,920
And as life evolved,
277
00:21:59,240 --> 00:22:01,840
it synchronized to Earth's motion.
278
00:22:02,880 --> 00:22:04,680
So that today,
279
00:22:04,760 --> 00:22:09,400
these clocks exist
in almost every creature on Earth.
280
00:22:13,640 --> 00:22:16,440
Although some creatures prefer day
and others night…
281
00:22:22,320 --> 00:22:26,200
all life is dancing to the same beat.
282
00:22:26,280 --> 00:22:28,000
[dramatic music playing]
283
00:22:28,720 --> 00:22:30,960
Thanks to cellular clocks
284
00:22:31,040 --> 00:22:36,240
that tick in time
with the spin of our Earth.
285
00:22:36,320 --> 00:22:40,600
[whooshing]
286
00:22:50,680 --> 00:22:51,600
[clock ticks]
287
00:22:53,000 --> 00:22:55,520
As yesterday becomes a memory…
288
00:22:55,600 --> 00:22:57,960
[pensive music playing]
289
00:22:58,040 --> 00:23:00,440
…another new day begins in the forest.
290
00:23:00,520 --> 00:23:02,880
[chimpanzees hooting]
291
00:23:09,560 --> 00:23:11,000
A fresh cycle,
292
00:23:12,760 --> 00:23:17,160
and yet, no clock can ever truly be reset.
293
00:23:24,720 --> 00:23:29,240
And there are subtle clues
all around the forest that reveal why.
294
00:23:32,440 --> 00:23:38,040
Nothing is the same today
as it was yesterday.
295
00:23:42,200 --> 00:23:44,640
Least of all Apollo,
296
00:23:45,720 --> 00:23:49,160
who seems to have woken up
on the wrong side of the bed.
297
00:23:51,680 --> 00:23:52,520
[grunts]
298
00:23:57,600 --> 00:23:59,320
When he's in a bad mood…
299
00:24:03,200 --> 00:24:07,840
the rest of the group
just need to keep their heads down.
300
00:24:07,920 --> 00:24:10,280
[chimpanzees hooting]
301
00:24:11,680 --> 00:24:14,080
[ominous music playing]
302
00:24:23,680 --> 00:24:25,560
[Apollo grunting]
303
00:24:26,720 --> 00:24:29,560
He soon finds a target
for his rage, though.
304
00:24:33,800 --> 00:24:36,040
[bees buzzing]
305
00:24:40,680 --> 00:24:44,120
Some of the younger chimps
have found honey for breakfast.
306
00:24:46,280 --> 00:24:48,720
[ominous music continues]
307
00:24:56,680 --> 00:25:00,240
And they forgot
to invite Apollo to join them.
308
00:25:02,280 --> 00:25:03,600
[chimpanzee hooting]
309
00:25:06,280 --> 00:25:07,880
[ominous music crescendos]
310
00:25:07,960 --> 00:25:10,080
[chimpanzees screeching]
311
00:25:14,640 --> 00:25:19,080
You soon learn, never get
on the wrong side of the dominant male.
312
00:25:19,160 --> 00:25:20,600
[hooting]
313
00:25:22,360 --> 00:25:24,880
[chimpanzees screeching]
314
00:25:24,960 --> 00:25:26,800
[solemn music playing]
315
00:25:26,880 --> 00:25:28,400
He's got a nasty bite.
316
00:25:32,280 --> 00:25:34,800
Thankfully, it's not too serious.
317
00:25:43,200 --> 00:25:46,440
With a bit of care,
this wound should heal.
318
00:25:49,360 --> 00:25:53,040
But wounds leave behind scars,
319
00:25:54,160 --> 00:25:56,120
etched into the chimps' bodies.
320
00:25:57,400 --> 00:26:03,520
Indelible marks of the past that reveal
the one universal truth about time.
321
00:26:07,280 --> 00:26:08,560
It has a direction.
322
00:26:10,640 --> 00:26:13,000
You can never go back in time…
323
00:26:13,080 --> 00:26:14,560
[sound effects playing in reverse]
324
00:26:14,640 --> 00:26:17,320
…only forward into the future.
325
00:26:17,400 --> 00:26:20,720
[clock ticking continuously]
326
00:26:20,800 --> 00:26:22,920
This is time's arrow,
327
00:26:24,200 --> 00:26:27,840
and it leaves scars on everything
328
00:26:28,520 --> 00:26:29,480
across Earth…
329
00:26:29,560 --> 00:26:31,160
[clock ticking rapidly]
330
00:26:31,240 --> 00:26:32,400
…and beyond.
331
00:26:35,040 --> 00:26:37,680
[rapid ticks morph into rhythmic music]
332
00:26:41,160 --> 00:26:46,520
Our moon is pockmarked with battle scars
that tell stories of ancient events.
333
00:26:56,480 --> 00:26:57,840
So too are the planets.
334
00:27:01,680 --> 00:27:08,640
Their surfaces testament to a lifetime
of bombardment by asteroids and comets.
335
00:27:08,720 --> 00:27:10,480
[rhythmic music continues]
336
00:27:15,040 --> 00:27:19,120
But perhaps the most impressive
impact crater in our solar system
337
00:27:20,680 --> 00:27:23,080
belongs to a moon of Saturn.
338
00:27:24,480 --> 00:27:25,480
Mimas.
339
00:27:27,880 --> 00:27:32,560
The Herschel crater
is 130 kilometers across.
340
00:27:38,280 --> 00:27:40,840
Whatever created this enormous scar…
341
00:27:43,000 --> 00:27:46,280
must have come close
to shattering the moon to pieces.
342
00:27:54,880 --> 00:27:57,480
[intense electronic music playing]
343
00:28:04,000 --> 00:28:06,080
Mimas lives to tell the tale.
344
00:28:07,840 --> 00:28:10,400
But events like this are irreversible.
345
00:28:10,920 --> 00:28:12,960
[whooshing]
346
00:28:15,320 --> 00:28:19,360
And they differentiate the past
from the present.
347
00:28:19,440 --> 00:28:20,880
[intriguing music playing]
348
00:28:22,160 --> 00:28:24,600
Impact craters are timestamps
349
00:28:26,360 --> 00:28:28,840
that mark a unique moment in history.
350
00:28:37,400 --> 00:28:40,360
We can never revisit the moment
they were created.
351
00:28:43,960 --> 00:28:47,640
But we can piece together traces
of past events
352
00:28:49,080 --> 00:28:51,480
and map a course back through time.
353
00:28:56,640 --> 00:28:57,880
Before craters.
354
00:28:57,960 --> 00:28:59,560
[sound effects playing in reverse]
355
00:28:59,640 --> 00:29:00,920
Before planets.
356
00:29:01,840 --> 00:29:03,080
Before stars.
357
00:29:05,000 --> 00:29:07,680
Back to a time before time.
358
00:29:14,400 --> 00:29:17,400
Our universe had a beginning.
359
00:29:18,080 --> 00:29:19,480
[explosion rumbles]
360
00:29:20,120 --> 00:29:21,760
[dramatic music playing]
361
00:29:21,840 --> 00:29:24,960
A very big bang…
362
00:29:27,360 --> 00:29:29,800
that created three-dimensional space
363
00:29:31,280 --> 00:29:32,560
and time.
364
00:29:36,880 --> 00:29:40,240
But space and time are not separate.
365
00:29:41,800 --> 00:29:44,840
Time is woven
into the fabric of the universe.
366
00:29:45,360 --> 00:29:46,920
[dramatic music continues]
367
00:29:49,240 --> 00:29:54,120
Bound to space
as our universe's fourth dimension.
368
00:29:56,480 --> 00:29:59,400
The Big Bang
set the universe's clock ticking.
369
00:30:02,920 --> 00:30:05,280
Propelling everything into the future.
370
00:30:05,360 --> 00:30:07,080
[zapping]
371
00:30:07,160 --> 00:30:08,960
[dramatic music crescendos]
372
00:30:09,040 --> 00:30:13,040
It created the arrow of time.
373
00:30:14,640 --> 00:30:17,200
[insects, birds chirping]
374
00:30:18,640 --> 00:30:21,960
From our universe's very first moments…
375
00:30:22,560 --> 00:30:23,440
[clock ticks]
376
00:30:25,840 --> 00:30:26,720
[clock ticks]
377
00:30:29,080 --> 00:30:29,960
[clock ticks]
378
00:30:30,040 --> 00:30:32,280
[calm music playing]
379
00:30:32,360 --> 00:30:34,640
…it pushes us all into the future,
380
00:30:35,720 --> 00:30:38,200
causing everything to grow,
381
00:30:39,640 --> 00:30:40,480
age…
382
00:30:40,560 --> 00:30:41,440
[clock ticks]
383
00:30:42,440 --> 00:30:43,400
…and change.
384
00:30:43,920 --> 00:30:44,800
[clock ticks]
385
00:30:45,560 --> 00:30:47,000
From childhood…
386
00:30:47,080 --> 00:30:47,920
[clock ticks]
387
00:30:48,000 --> 00:30:49,120
…to adulthood,
388
00:30:50,400 --> 00:30:54,080
we all travel through life
in the same direction.
389
00:30:55,640 --> 00:30:58,320
Getting older day by day.
390
00:30:59,960 --> 00:31:02,800
And with age comes wisdom
391
00:31:04,200 --> 00:31:07,640
as youthful innocence
is replaced by experience.
392
00:31:07,720 --> 00:31:09,720
[chimpanzee grunting]
393
00:31:13,120 --> 00:31:17,520
Time's arrow leads us through
these stages of life.
394
00:31:17,600 --> 00:31:19,680
[calm music continues]
395
00:31:21,880 --> 00:31:23,080
It shapes us.
396
00:31:25,760 --> 00:31:27,440
Defines who we are.
397
00:31:31,000 --> 00:31:32,520
From our first moments…
398
00:31:34,680 --> 00:31:35,800
to our last.
399
00:31:41,880 --> 00:31:44,480
Chimps rarely live past the age of 40.
400
00:31:49,200 --> 00:31:50,840
Nothing is immortal.
401
00:31:52,480 --> 00:31:54,280
[solemn music playing]
402
00:31:58,480 --> 00:32:03,240
Everything that exists in our universe
has a finite lifespan.
403
00:32:08,680 --> 00:32:11,960
Including, perhaps, the universe itself.
404
00:32:14,400 --> 00:32:18,080
[whooshing]
405
00:32:19,600 --> 00:32:23,440
Today, the galaxies are filled with stars.
406
00:32:27,280 --> 00:32:33,600
But 95% of stars that will ever exist
have already been born.
407
00:32:36,680 --> 00:32:38,720
[solemn music continues]
-[clock ticks]
408
00:32:38,800 --> 00:32:41,400
So, as our universe
journeys into the future…
409
00:32:41,480 --> 00:32:42,720
[clock ticks]
410
00:32:42,800 --> 00:32:44,080
…the stars…
411
00:32:44,760 --> 00:32:47,800
-[clock ticks]
-…one by one, will blink out…
412
00:32:47,880 --> 00:32:48,760
[clock ticks]
413
00:32:50,320 --> 00:32:55,200
…leaving the universe
to face an ever-darkening future,
414
00:32:56,880 --> 00:32:58,680
stretching out for trillions,
415
00:32:59,400 --> 00:33:02,920
that's thousands of billions, of years.
416
00:33:05,480 --> 00:33:07,800
[solemn music continues]
417
00:33:09,400 --> 00:33:11,640
The age of starlight
418
00:33:11,720 --> 00:33:16,280
will be followed by a dark age
of black holes.
419
00:33:17,600 --> 00:33:19,800
[eerie music playing]
420
00:33:22,920 --> 00:33:27,840
These monsters feed on the remnants
of dead stars and planets.
421
00:33:29,560 --> 00:33:31,040
And as they do,
422
00:33:31,120 --> 00:33:36,320
their ever-increasing gravity scars
the very fabric of the universe.
423
00:33:36,400 --> 00:33:38,680
[zapping, whooshing]
424
00:33:43,080 --> 00:33:46,400
Distorting both space and time.
425
00:33:48,760 --> 00:33:53,080
The edge of a black hole,
called the event horizon,
426
00:33:54,240 --> 00:33:57,400
is a region where gravity
has become so strong
427
00:33:58,240 --> 00:34:03,880
it causes time
to slow down practically to a standstill.
428
00:34:04,880 --> 00:34:06,560
[eerie music crescendos]
429
00:34:08,960 --> 00:34:12,280
But even black holes
can't escape time's arrow.
430
00:34:12,360 --> 00:34:14,960
[solemn music playing]
431
00:34:15,040 --> 00:34:16,920
In the far, far future…
432
00:34:18,360 --> 00:34:21,000
[clock ticking]
433
00:34:21,080 --> 00:34:24,360
…when there are no stars
or planets left to consume,
434
00:34:25,920 --> 00:34:27,600
they will begin to starve.
435
00:34:32,800 --> 00:34:34,000
And slowly…
436
00:34:36,680 --> 00:34:37,920
very slowly,
437
00:34:39,720 --> 00:34:40,840
they will shrink.
438
00:34:42,480 --> 00:34:45,000
[suspenseful music playing]
439
00:34:46,360 --> 00:34:48,000
When they die,
440
00:34:48,080 --> 00:34:50,400
no one truly knows what comes next.
441
00:34:52,920 --> 00:34:57,960
But it could be the end of our universe.
442
00:35:03,720 --> 00:35:06,200
[insects, birds chirping]
443
00:35:07,400 --> 00:35:11,760
Here on Earth, none of us can slow
the passage of time.
444
00:35:16,000 --> 00:35:20,280
And one of Celeste's aunts
is reaching the end of her time.
445
00:35:22,360 --> 00:35:24,200
[somber music playing]
446
00:35:24,280 --> 00:35:28,040
Retreating from the group,
she heads into the forest alone.
447
00:35:35,800 --> 00:35:37,840
She has lived many years.
448
00:35:41,200 --> 00:35:44,080
But this day will be her last.
449
00:35:44,800 --> 00:35:47,480
[somber music continues]
450
00:36:03,760 --> 00:36:06,520
While the world continues to spin,
451
00:36:07,920 --> 00:36:11,040
her body lies still.
452
00:36:14,600 --> 00:36:17,280
[somber music crescendos]
453
00:36:19,560 --> 00:36:22,080
[whooshing]
454
00:36:23,320 --> 00:36:26,160
But time doesn't just carry us
toward endings.
455
00:36:30,360 --> 00:36:32,400
It also creates beginnings.
456
00:36:33,240 --> 00:36:35,800
[ethereal music playing]
457
00:36:37,280 --> 00:36:40,760
As days turn into weeks
and weeks into months,
458
00:36:42,560 --> 00:36:45,600
there are big changes
for one special chimpanzee.
459
00:36:47,480 --> 00:36:48,960
[whooshing]
460
00:36:49,040 --> 00:36:51,480
[intriguing music playing]
461
00:36:51,560 --> 00:36:54,960
[heartbeat thumping softly]
462
00:36:59,600 --> 00:37:01,480
Say hello to Cosmo.
463
00:37:06,040 --> 00:37:08,960
Her brain and limbs are now fully formed.
464
00:37:10,720 --> 00:37:13,400
And her eyes are ready to see the world.
465
00:37:13,480 --> 00:37:15,800
[intriguing music continues]
466
00:37:21,880 --> 00:37:24,960
The exact timing
of her birth is impossible to know.
467
00:37:26,560 --> 00:37:29,400
But she could be born any day now.
468
00:37:29,480 --> 00:37:31,640
[dramatic vocal music playing]
469
00:37:36,000 --> 00:37:38,760
She's been in the womb for eight months.
470
00:37:40,240 --> 00:37:43,480
But her journey began long, long ago.
471
00:37:44,600 --> 00:37:45,920
[whooshing, explosion rumbles]
472
00:37:46,000 --> 00:37:50,600
The elements that made her
came from dying stars.
473
00:37:51,240 --> 00:37:52,440
[whooshing]
474
00:37:52,520 --> 00:37:58,320
The water that flows through her body
came from distant worlds.
475
00:37:58,400 --> 00:38:00,320
[dramatic music playing]
476
00:38:00,400 --> 00:38:06,920
The energy that powers her muscles
came from the heart of our sun.
477
00:38:07,000 --> 00:38:08,600
[explosion rumbles]
478
00:38:09,720 --> 00:38:13,040
But it's that most mysterious ingredient,
479
00:38:13,720 --> 00:38:18,200
the one that started ticking
13.8 billion years ago…
480
00:38:22,280 --> 00:38:26,800
that has led all other ingredients
to this moment.
481
00:38:30,120 --> 00:38:31,240
In this place.
482
00:38:31,320 --> 00:38:33,280
[ethereal music playing]
483
00:38:33,960 --> 00:38:35,200
On this planet.
484
00:38:40,600 --> 00:38:44,640
-[birds chirping]
-[chimpanzees hooting]
485
00:38:44,720 --> 00:38:47,920
Another sunrise, another morning.
486
00:38:48,000 --> 00:38:50,400
[calm music playing]
487
00:38:53,240 --> 00:38:57,520
And this one is extra special.
488
00:39:08,120 --> 00:39:10,520
Welcome to Earth, Cosmo.
489
00:39:13,080 --> 00:39:15,360
[Cosmo grunting]
490
00:39:15,440 --> 00:39:18,680
This precious moment
will never be repeated for Celeste.
491
00:39:19,480 --> 00:39:22,760
But Cosmo's journey has just begun.
492
00:39:26,000 --> 00:39:28,280
It will take around three months
493
00:39:28,360 --> 00:39:32,040
for her body clock to synchronize
to the rhythm of the planet,
494
00:39:33,840 --> 00:39:36,400
one year before she can truly communicate,
495
00:39:38,080 --> 00:39:42,680
and perhaps 15 years
until she is fully grown.
496
00:39:45,760 --> 00:39:47,520
So much lies ahead.
497
00:39:49,720 --> 00:39:51,800
[Cosmo grunting]
498
00:39:53,000 --> 00:39:54,800
[whooshing]
499
00:39:56,320 --> 00:39:57,600
Like Cosmo,
500
00:39:58,320 --> 00:40:01,360
our universe is still in its infancy
501
00:40:02,400 --> 00:40:06,640
at the beginning
of an unimaginably long lifespan.
502
00:40:06,720 --> 00:40:08,600
[majestic music playing]
503
00:40:08,680 --> 00:40:11,920
We are living in the age of starlight.
504
00:40:14,200 --> 00:40:19,160
A moment when time's arrow
has filled the universe with beauty…
505
00:40:20,960 --> 00:40:22,360
[penguins squawking]
506
00:40:22,440 --> 00:40:23,400
…and wonder.
507
00:40:23,480 --> 00:40:25,120
[majestic music continues]
508
00:40:32,360 --> 00:40:34,520
But it's a brief window of time
509
00:40:35,440 --> 00:40:39,200
that will never be repeated
in the history of our universe.
510
00:40:45,320 --> 00:40:47,720
No one can slow the passage of time,
511
00:40:49,080 --> 00:40:50,160
nor should we try.
512
00:40:55,280 --> 00:40:56,920
Because without time,
513
00:40:58,120 --> 00:40:59,480
there would be no now.
514
00:41:06,720 --> 00:41:08,160
No moment in the sun.
515
00:41:17,200 --> 00:41:18,920
No moments, period.
516
00:41:24,600 --> 00:41:25,720
Without time,
517
00:41:27,760 --> 00:41:29,160
there would be no life.
518
00:41:40,000 --> 00:41:41,240
[whooshing]
519
00:41:41,320 --> 00:41:44,120
Next in the story of our universe,
520
00:41:45,800 --> 00:41:47,440
Earth's seasons.
521
00:41:47,520 --> 00:41:48,880
[playful music playing]
522
00:41:48,960 --> 00:41:51,760
Like a mother bear raising her cubs…
523
00:41:51,840 --> 00:41:53,040
[cub groans]
524
00:41:53,120 --> 00:41:56,680
…we all experience
our planet's yearly transformations.
525
00:41:56,760 --> 00:41:58,400
[bear roars]
526
00:41:59,760 --> 00:42:02,280
But what created Earth's seasons?
527
00:42:03,120 --> 00:42:04,680
[rumbling]
528
00:42:04,760 --> 00:42:05,680
[crashing]
529
00:42:05,760 --> 00:42:08,840
How are they connected
to the formation of our moon?
530
00:42:09,880 --> 00:42:15,680
And why does only our planet
have conditions just right for life?
531
00:42:17,880 --> 00:42:19,080
[cub whines]
532
00:42:21,280 --> 00:42:24,080
[dramatic music playing]