WEBVTT

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(Birds chirping)

NOTE Paragraph

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We're here at the University
of California, Santa Barbara

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to discuss a dream of humanity:

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the ability to exit our solar system

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and enter another solar system.

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And the solution is literally
before your eyes.

NOTE Paragraph

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So I have two things on me
that you have -- I have a watch,

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and I have a flashlight,

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which, if it's not on you,
it's on your phone.

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So the watch keeps time,

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and my flashlight
just illuminates my environment.

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So like art, to me,
science is illuminating.

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I want to see reality in a different way.

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When I turn on the flashlight,

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suddenly the dark becomes bright,
and I suddenly see.

NOTE Paragraph

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The flashlight and its light,

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which you can see coming out --

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the light on my hand
is not only illuminating my hand,

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it's actually pushing on my hand.

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Light carries energy and momentum.

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So the answer is not to make a spacecraft
out of a flashlight,

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by having the exhaust come out this way

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and the spacecraft goes that way --

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that's what we do today with chemistry.

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The answer is this:

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Take the flashlight and put it
somewhere on the Earth,

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in orbit or on the Moon,

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and then shine it on a reflector,

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which propels the reflector to speeds
which can approach the speed of light.

NOTE Paragraph

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Well, how do you make a flashlight
that's big enough?

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This isn't going to do it,

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my hand doesn't seem to be going anywhere.

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And that's because the force
is very, very low.

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So the way that you can solve this problem

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is taking many, many flashlights,
which are actually lasers,

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and synchronizing them in time,

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and when you gang them all together
into a gigantic array,

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which we call a phased array,

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you then have a sufficiently
powerful system,

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which, if you make it roughly
the size of a city,

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it can push a spacecraft,
which is roughly the size of your hand,

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to speeds which are roughly
25 percent the speed of light.

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That would enable us to get
to the nearest star, Proxima Centauri,

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which is a little over
four light years away,

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in less than 20 years.

NOTE Paragraph

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Initial probes would be
roughly the size of your hand,

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and the size of the reflector
that you're going to use

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is going to be roughly human size,

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so not a whole lot larger than myself,

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but a few meters in size.

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It only uses the reflection of light
from this very large laser array

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to propel the spacecraft.

NOTE Paragraph

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So let's talk about this.

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This is a lot like sailing on the ocean.

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When you sail on the ocean,
you're pushed by the wind.

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And the wind then drives the sail
forward through the water.

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In our case, we're creating
an artificial wind in space

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from this laser array,

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except the wind is actually the photons
from the laser itself,

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the light from the laser becomes the wind

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upon which we sail.

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It is a very directed light --

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it's often called directed energy.

NOTE Paragraph

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So why is this possible today,

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why can we talk about
going to the stars today,

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when 60 years ago,

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when the space program began in earnest,

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people would have said,
"That's not possible"?

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Well, the reason it's possible today
has a lot to do with the consumer,

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and the very fact that you're watching me.

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You're watching me
over a high-speed internet,

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which is dominated by the photonics
of sending data over fiber optics.

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Photonics essentially allow
the internet to exist

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in the way it does today.

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The ability to send vast amounts
of data very quickly

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is the same technology
that we're going to use

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to send spacecraft
very quickly to the stars.

NOTE Paragraph

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You effectively have an infinite
supply of propellent,

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you can turn it on and off as needed.

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You do not leave the laser array
that produces the light on

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for the entire journey.

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For small spacecraft,
it's only on for a few minutes,

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and then it's like shooting a gun.

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You have a projectile
which just moves ballistically.

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Even if we, as humans,
are not on the spacecraft,

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at least we have the ability
to send out such spacecraft.

NOTE Paragraph

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You want to remotely view,

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or have remote imaging and remote sensing,

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of an object.

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So when we go to Jupiter, for example,

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with a flyby mission,

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we are taking pictures of Jupiter,

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we're measuring the magnetic field,

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the particle density,

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and we're basically exploring remotely.

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The same way that you are looking at me.

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And all of the current missions
that are beyond the Moon

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are remote-sensing missions.

NOTE Paragraph

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What would we hope to find
if we visited an exoplanet?

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Perhaps there's life on an exoplanet,

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and we would be able to see
evidence of life,

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either through atmospheric biosignatures

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or through, you know, a dramatic picture,

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we would be able to see something
actually on the surface.

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We don't know if there's life
elsewhere in the universe.

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Perhaps on the missions that we send out,
we will find evidence for life,

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perhaps we will not.

NOTE Paragraph

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And while economics may seem
like an inappropriate thing

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to bring into a talk
on interstellar capability,

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it is in fact one of the driving issues
in achieving interstellar capability.

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You have to get things to the point
where they're economically affordable

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to do what we want to do.

NOTE Paragraph

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So currently,

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we have systems in the lab

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which have achieved the ability
to synchronize over very large scales,

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out to about 10 kilometers
or roughly six miles.

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We've been able to achieve
synchronization of laser systems,

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and it's worked beautifully.

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We've known how to build lasers
for many decades,

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but it's only now that the technology
has gotten inexpensive enough,

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and become mature enough

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that we can imagine
having huge arrays, literally,

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kilometer-scale arrays,
much like solar farms,

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but instead of receiving light,
they transmit light.

NOTE Paragraph

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The beauty of this type of technology
is it enables many applications,

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not just relativistic flight
for small spacecraft,

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but enables high-speed spacecraft,

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high-speed flight in our solar system,

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it enables planetary defense,

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it enables space debris removal,

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it enables powering of distant assets
that we may want to send power to,

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such as spacecraft or bases
on the Moon or other places.

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It's an extremely versatile technology,

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it's something that humanity
would want to develop

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even if they didn't want
to send spacecraft to the stars,

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because that technology
allows so many applications

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that are currently not feasible.

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And therefore, I feel
it's an inevitable technology,

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because we have the ability,

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we just need to fine-tune the technology

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and in a sense, wait for economics
to catch up with us

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so that it becomes cheap enough
to build the large systems.

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The smaller systems are affordable now.

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And we've already started building
prototype systems in our lab.

NOTE Paragraph

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So while it's not
going to happen tomorrow,

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we've already begun the process,

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and so far, it's looking good.

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This is both a revolutionary program,

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in terms of being
a transformative technology,

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but it's also an evolutionary program.

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So personally,
I do not expect to be around

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when the first
relativistic flight happens.

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I think that's probably 30-plus years off
before we get to that point,

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and perhaps more.

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But what inspires me

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is to look at the ability
to achieve the final goal.

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Even if it does not happen in my lifetime,

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it can happen in the lifetime
of the next generation

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or the generation beyond that.

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The consequences are so transformative

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that we literally, in my opinion,
must go down this path,

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and must explore what the limitations are,

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and then how do we overcome
the limitations.

NOTE Paragraph

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The search for life on other planets

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would be one of humanity's
foremost explorations,

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and if we're able to do so,

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and actually find life on another planet,

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it would change humanity forever.

NOTE Paragraph

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Everything is profound in life.

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If you look deep enough,

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you'll find something incredibly complex
and interesting and beautiful in life.

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And the same is true
with the lowly photon

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that we use to see every day.

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But when we look outside
and we imagine something vastly greater,

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an array of lasers that are synchronized,

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we could imagine things
which are just extraordinary in life.

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And the ability to go to another star

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is one of those
extraordinary capabilities.