WEBVTT

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We've got the biggest
dreams of putting

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our eyes on other worlds,
traveling to them,

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making them our home.

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But how do we get there?

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The stars are so far apart.

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We would need sailing
ships that could

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sustain human crews over the
longest haul of all time.

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The nearest star is
four light years away.

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That's 24 trillion miles
to Proxima Centauri.

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Just to give you some
idea of how far away

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that point of light really is.

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If NASA's Voyager
1 spacecraft, which

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moves at a pretty good clip--

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38,000 miles an hour--

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was headed for Proxima Centauri,
it would take 70,000 years

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to get there and
that's only the nearest

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star out of the hundreds of
billions in our galaxy alone.

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[music playing]

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So if we want to
endure as a species

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beyond the projected shelf
life of our own planet,

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we'd better act like
the Polynesians.

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We need to take what
we know of nature

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and build sailing ships
that can ride the light

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as they once rode the wind.

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These sails are
enormous, miles high,

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but they're very
thin, 1,000 times

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thinner than a garbage bag.

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[music playing]

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When a photon of light strikes
those magnificent sails,

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it gives them a little push.

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[music playing]

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This means that in
the vacuum of space

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even the tiniest
push from a photon

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will propel them ever
faster until they're

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moving at a significant
fraction of the speed of light.

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[music playing]

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When you get too far from your
star and the light dwindles,

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lasers can do the trick.

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[music playing]

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If we were to lightsail our
way to Proxima Centauri,

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it wouldn't take 70,000
years, but only 20 years.

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[music playing]

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Proxima B lies in the
habitable zone of its star,

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but we don't yet know if
it could support life.

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Does it have a kind of
protective magnetic field

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that has sheltered
the evolution of life

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on the surface of our world?

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Another consequence of Proxima
B's close location to its star

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is that the planet is
probably tidally locked,

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one side perpetually
facing the star,

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the other doomed
to endless night.

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[music playing]