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← How humanity can reach the stars

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Showing Revision 5 created 09/25/2020 by marialadias.

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

  2. to discuss a dream of humanity:
  3. the ability to exit our solar system
  4. and enter another solar system.
  5. And the solution is literally
    before your eyes.
  6. So I have two things on me
    that you have -- I have a watch,

  7. and I have a flashlight,
  8. which, if it's not on you,
    it's on your phone.
  9. So the watch keeps time,
  10. and my flashlight
    just illuminates my environment.
  11. So like art, to me,
    science is illuminating.
  12. I want to see reality in a different way.
  13. When I turn on the flashlight,
  14. suddenly the dark becomes bright,
    and I suddenly see.
  15. The flashlight and its light,

  16. which you can see coming out --
  17. the light on my hand
    is not only illuminating my hand,
  18. it's actually pushing on my hand.
  19. Light carries energy and momentum.
  20. So the answer is not to make a spacecraft
    out of a flashlight,
  21. by having the exhaust come out this way
  22. and the spacecraft goes that way --
  23. that's what we do today with chemistry.
  24. The answer is this:
  25. Take the flashlight and put it
    somewhere on the Earth,
  26. in orbit or on the Moon,
  27. and then shine it on a reflector,
  28. which propels the reflector to speeds
    which can approach the speed of light.
  29. Well, how do you make a flashlight
    that's big enough?

  30. This isn't going to do it,
  31. my hand doesn't seem to be going anywhere.
  32. And that's because the force
    is very, very low.
  33. So the way that you can solve this problem
  34. is taking many, many flashlights,
    which are actually lasers,
  35. and synchronizing them in time,
  36. and when you gang them all together
    into a gigantic array,
  37. which we call a phased array,
  38. you then have a sufficiently
    powerful system,
  39. which, if you make it roughly
    the size of a city,
  40. it can push a spacecraft,
    which is roughly the size of your hand,
  41. to speeds which are roughly
    25 percent the speed of light.
  42. That would enable us to get
    to the nearest star, Proxima Centauri,
  43. which is a little over
    four light years away,
  44. in less than 20 years.
  45. Initial probes would be
    roughly the size of your hand,

  46. and the size of the reflector
    that you're going to use
  47. is going to be roughly human size,
  48. so not a whole lot larger than myself,
  49. but a few meters in size.
  50. It only uses the reflection of light
    from this very large laser array
  51. to propel the spacecraft.
  52. So let's talk about this.

  53. This is a lot like sailing on the ocean.
  54. When you sail on the ocean,
    you're pushed by the wind.
  55. And the wind then drives the sail
    forward through the water.
  56. In our case, we're creating
    an artificial wind in space
  57. from this laser array,
  58. except the wind is actually the photons
    from the laser itself,
  59. the light from the laser becomes the wind
  60. upon which we sail.
  61. It is a very directed light --
  62. it's often called directed energy.
  63. So why is this possible today,

  64. why can we talk about
    going to the stars today,
  65. when 60 years ago,
  66. when the space program began in earnest,
  67. people would have said,
    "That's not possible"?
  68. Well, the reason it's possible today
    has a lot to do with the consumer,
  69. and the very fact that you're watching me.
  70. You're watching me
    over a high-speed internet,
  71. which is dominated by the photonics
    of sending data over fiber optics.
  72. Photonics essentially allow
    the internet to exist
  73. in the way it does today.
  74. The ability to send vast amounts
    of data very quickly
  75. is the same technology
    that we're going to use
  76. to send spacecraft
    very quickly to the stars.
  77. You effectively have an infinite
    supply of propellent,

  78. you can turn it on and off as needed.
  79. You do not leave the laser array
    that produces the light on
  80. for the entire journey.
  81. For small spacecraft,
    it's only on for a few minutes,
  82. and then it's like shooting a gun.
  83. You have a projectile
    which just moves ballistically.
  84. Even if we, as humans,
    are not on the spacecraft,
  85. at least we have the ability
    to send out such spacecraft.
  86. You want to remotely view,

  87. or have remote imaging and remote sensing,
  88. of an object.
  89. So when we go to Jupiter, for example,
  90. with a flyby mission,
  91. we are taking pictures of Jupiter,
  92. we're measuring the magnetic field,
  93. the particle density,
  94. and we're basically exploring remotely.
  95. The same way that you are looking at me.
  96. And all of the current missions
    that are beyond the Moon
  97. are remote-sensing missions.
  98. What would we hope to find
    if we visited an exoplanet?

  99. Perhaps there's life on an exoplanet,
  100. and we would be able to see
    evidence of life,
  101. either through atmospheric biosignatures
  102. or through, you know, a dramatic picture,
  103. we would be able to see something
    actually on the surface.
  104. We don't know if there's life
    elsewhere in the universe.
  105. Perhaps on the missions that we send out,
    we will find evidence for life,
  106. perhaps we will not.
  107. And while economics may seem
    like an inappropriate thing

  108. to bring into a talk
    on interstellar capability,
  109. it is in fact one of the driving issues
    in achieving interstellar capability.
  110. You have to get things to the point
    where they're economically affordable
  111. to do what we want to do.
  112. So currently,

  113. we have systems in the lab
  114. which have achieved the ability
    to synchronize over very large scales,
  115. out to about 10 kilometers
    or roughly six miles.
  116. We've been able to achieve
    synchronization of laser systems,
  117. and it's worked beautifully.
  118. We've known how to build lasers
    for many decades,
  119. but it's only now that the technology
    has gotten inexpensive enough,
  120. and become mature enough
  121. that we can imagine
    having huge arrays, literally,
  122. kilometer-scale arrays,
    much like solar farms,
  123. but instead of receiving light,
    they transmit light.
  124. The beauty of this type of technology
    is it enables many applications,

  125. not just relativistic flight
    for small spacecraft,
  126. but enables high-speed spacecraft,
  127. high-speed flight in our solar system,
  128. it enables planetary defense,
  129. it enables space debris removal,
  130. it enables powering of distant assets
    that we may want to send power to,
  131. such as spacecraft or bases
    on the Moon or other places.
  132. It's an extremely versatile technology,
  133. it's something that humanity
    would want to develop
  134. even if they didn't want
    to send spacecraft to the stars,
  135. because that technology
    allows so many applications
  136. that are currently not feasible.
  137. And therefore, I feel
    it's an inevitable technology,
  138. because we have the ability,
  139. we just need to fine-tune the technology
  140. and in a sense, wait for economics
    to catch up with us
  141. so that it becomes cheap enough
    to build the large systems.
  142. The smaller systems are affordable now.
  143. And we've already started building
    prototype systems in our lab.
  144. So while it's not
    going to happen tomorrow,

  145. we've already begun the process,
  146. and so far, it's looking good.
  147. This is both a revolutionary program,
  148. in terms of being
    a transformative technology,
  149. but it's also an evolutionary program.
  150. So personally,
    I do not expect to be around
  151. when the first
    relativistic flight happens.
  152. I think that's probably 30-plus years off
    before we get to that point,
  153. and perhaps more.
  154. But what inspires me
  155. is to look at the ability
    to achieve the final goal.
  156. Even if it does not happen in my lifetime,
  157. it can happen in the lifetime
    of the next generation
  158. or the generation beyond that.
  159. The consequences are so transformative
  160. that we literally, in my opinion,
    must go down this path,
  161. and must explore what the limitations are,
  162. and then how do we overcome
    the limitations.
  163. The search for life on other planets

  164. would be one of humanity's
    foremost explorations,
  165. and if we're able to do so,
  166. and actually find life on another planet,
  167. it would change humanity forever.
  168. Everything is profound in life.

  169. If you look deep enough,
  170. you'll find something incredibly complex
    and interesting and beautiful in life.
  171. And the same is true
    with the lowly photon
  172. that we use to see every day.
  173. But when we look outside
    and we imagine something vastly greater,
  174. an array of lasers that are synchronized,
  175. we could imagine things
    which are just extraordinary in life.
  176. And the ability to go to another star
  177. is one of those
    extraordinary capabilities.
  178. (Birds chirping)