1 00:08:09,317 --> 00:08:14,298 (Birds chirping) 2 00:00:00,595 --> 00:00:03,746 We're here at the University of California, Santa Barbara 3 00:00:03,770 --> 00:00:06,357 to discuss a dream of humanity: 4 00:00:06,381 --> 00:00:09,363 the ability to exit our solar system 5 00:00:09,387 --> 00:00:11,569 and enter another solar system. 6 00:00:11,593 --> 00:00:15,177 And the solution is literally before your eyes. 7 00:00:15,621 --> 00:00:18,383 So I have two things on me that you have -- I have a watch, 8 00:00:18,407 --> 00:00:19,813 and I have a flashlight, 9 00:00:19,837 --> 00:00:22,019 which, if it's not on you, it's on your phone. 10 00:00:22,043 --> 00:00:23,926 So the watch keeps time, 11 00:00:23,950 --> 00:00:27,195 and my flashlight just illuminates my environment. 12 00:00:27,219 --> 00:00:30,456 So like art, to me, science is illuminating. 13 00:00:30,480 --> 00:00:32,877 I want to see reality in a different way. 14 00:00:32,901 --> 00:00:34,410 When I turn on the flashlight, 15 00:00:34,434 --> 00:00:37,304 suddenly the dark becomes bright, and I suddenly see. 16 00:00:37,328 --> 00:00:38,963 The flashlight and its light, 17 00:00:38,987 --> 00:00:40,464 which you can see coming out -- 18 00:00:40,488 --> 00:00:43,042 the light on my hand is not only illuminating my hand, 19 00:00:43,066 --> 00:00:44,768 it's actually pushing on my hand. 20 00:00:44,792 --> 00:00:47,101 Light carries energy and momentum. 21 00:00:47,125 --> 00:00:50,201 So the answer is not to make a spacecraft out of a flashlight, 22 00:00:50,225 --> 00:00:52,154 by having the exhaust come out this way 23 00:00:52,178 --> 00:00:53,845 and the spacecraft goes that way -- 24 00:00:53,869 --> 00:00:55,741 that's what we do today with chemistry. 25 00:00:55,765 --> 00:00:56,947 The answer is this: 26 00:00:56,971 --> 00:00:59,515 Take the flashlight and put it somewhere on the Earth, 27 00:00:59,539 --> 00:01:00,774 in orbit or on the Moon, 28 00:01:00,798 --> 00:01:02,571 and then shine it on a reflector, 29 00:01:02,595 --> 00:01:06,903 which propels the reflector to speeds which can approach the speed of light. 30 00:01:06,927 --> 00:01:09,411 Well, how do you make a flashlight that's big enough? 31 00:01:09,435 --> 00:01:10,752 This isn't going to do it, 32 00:01:10,776 --> 00:01:12,855 my hand doesn't seem to be going anywhere. 33 00:01:12,879 --> 00:01:15,101 And that's because the force is very, very low. 34 00:01:15,125 --> 00:01:17,125 So the way that you can solve this problem 35 00:01:17,149 --> 00:01:19,964 is taking many, many flashlights, which are actually lasers, 36 00:01:19,988 --> 00:01:21,472 and synchronizing them in time, 37 00:01:21,496 --> 00:01:25,100 and when you gang them all together into a gigantic array, 38 00:01:25,124 --> 00:01:27,344 which we call a phased array, 39 00:01:27,368 --> 00:01:30,241 you then have a sufficiently powerful system, 40 00:01:30,265 --> 00:01:32,760 which, if you make it roughly the size of a city, 41 00:01:32,784 --> 00:01:36,910 it can push a spacecraft, which is roughly the size of your hand, 42 00:01:36,934 --> 00:01:41,161 to speeds which are roughly 25 percent the speed of light. 43 00:01:41,185 --> 00:01:44,979 That would enable us to get to the nearest star, Proxima Centauri, 44 00:01:45,003 --> 00:01:47,450 which is a little over four light years away, 45 00:01:47,474 --> 00:01:49,474 in less than 20 years. 46 00:01:50,019 --> 00:01:52,947 Initial probes would be roughly the size of your hand, 47 00:01:52,971 --> 00:01:55,577 and the size of the reflector that you're going to use 48 00:01:55,601 --> 00:01:57,490 is going to be roughly human size, 49 00:01:57,514 --> 00:01:59,529 so not a whole lot larger than myself, 50 00:01:59,553 --> 00:02:01,466 but a few meters in size. 51 00:02:01,490 --> 00:02:07,561 It only uses the reflection of light from this very large laser array 52 00:02:07,585 --> 00:02:09,379 to propel the spacecraft. 53 00:02:09,403 --> 00:02:11,378 So let's talk about this. 54 00:02:11,402 --> 00:02:14,583 This is a lot like sailing on the ocean. 55 00:02:14,607 --> 00:02:17,822 When you sail on the ocean, you're pushed by the wind. 56 00:02:17,846 --> 00:02:20,679 And the wind then drives the sail forward through the water. 57 00:02:20,703 --> 00:02:24,398 In our case, we're creating an artificial wind in space 58 00:02:24,422 --> 00:02:25,699 from this laser array, 59 00:02:25,723 --> 00:02:29,049 except the wind is actually the photons from the laser itself, 60 00:02:29,073 --> 00:02:32,196 the light from the laser becomes the wind 61 00:02:32,220 --> 00:02:33,545 upon which we sail. 62 00:02:33,569 --> 00:02:35,100 It is a very directed light -- 63 00:02:35,124 --> 00:02:37,248 it's often called directed energy. 64 00:02:37,272 --> 00:02:38,702 So why is this possible today, 65 00:02:38,726 --> 00:02:41,268 why can we talk about going to the stars today, 66 00:02:41,292 --> 00:02:42,971 when 60 years ago, 67 00:02:42,995 --> 00:02:45,514 when the space program began in earnest, 68 00:02:45,538 --> 00:02:47,728 people would have said, "That's not possible"? 69 00:02:47,752 --> 00:02:52,212 Well, the reason it's possible today has a lot to do with the consumer, 70 00:02:52,236 --> 00:02:54,236 and the very fact that you're watching me. 71 00:02:54,569 --> 00:02:56,855 You're watching me over a high-speed internet, 72 00:02:56,879 --> 00:03:02,307 which is dominated by the photonics of sending data over fiber optics. 73 00:03:02,776 --> 00:03:06,501 Photonics essentially allow the internet to exist 74 00:03:06,525 --> 00:03:07,799 in the way it does today. 75 00:03:07,823 --> 00:03:10,978 The ability to send vast amounts of data very quickly 76 00:03:11,002 --> 00:03:13,820 is the same technology that we're going to use 77 00:03:13,844 --> 00:03:16,958 to send spacecraft very quickly to the stars. 78 00:03:16,982 --> 00:03:19,530 You effectively have an infinite supply of propellent, 79 00:03:19,554 --> 00:03:21,403 you can turn it on and off as needed. 80 00:03:21,427 --> 00:03:26,772 You do not leave the laser array that produces the light on 81 00:03:26,796 --> 00:03:28,201 for the entire journey. 82 00:03:28,225 --> 00:03:30,757 For small spacecraft, it's only on for a few minutes, 83 00:03:30,781 --> 00:03:34,299 and then it's like shooting a gun. 84 00:03:34,323 --> 00:03:38,363 You have a projectile which just moves ballistically. 85 00:03:38,387 --> 00:03:41,847 Even if we, as humans, are not on the spacecraft, 86 00:03:41,871 --> 00:03:44,667 at least we have the ability to send out such spacecraft. 87 00:03:45,133 --> 00:03:47,320 You want to remotely view, 88 00:03:47,344 --> 00:03:50,844 or have remote imaging and remote sensing, 89 00:03:50,868 --> 00:03:52,264 of an object. 90 00:03:52,288 --> 00:03:54,887 So when we go to Jupiter, for example, 91 00:03:54,911 --> 00:03:56,950 with a flyby mission, 92 00:03:56,974 --> 00:03:58,609 we are taking pictures of Jupiter, 93 00:03:58,633 --> 00:04:00,316 we're measuring the magnetic field, 94 00:04:00,340 --> 00:04:01,514 the particle density, 95 00:04:01,538 --> 00:04:03,529 and we're basically exploring remotely. 96 00:04:03,553 --> 00:04:05,482 The same way that you are looking at me. 97 00:04:05,506 --> 00:04:08,823 And all of the current missions that are beyond the Moon 98 00:04:08,847 --> 00:04:10,887 are remote-sensing missions. 99 00:04:10,911 --> 00:04:13,744 What would we hope to find if we visited an exoplanet? 100 00:04:13,768 --> 00:04:16,141 Perhaps there's life on an exoplanet, 101 00:04:16,165 --> 00:04:18,744 and we would be able to see evidence of life, 102 00:04:18,768 --> 00:04:21,029 either through atmospheric biosignatures 103 00:04:21,053 --> 00:04:23,168 or through, you know, a dramatic picture, 104 00:04:23,192 --> 00:04:25,958 we would be able to see something actually on the surface. 105 00:04:25,982 --> 00:04:28,681 We don't know if there's life elsewhere in the universe. 106 00:04:28,705 --> 00:04:32,379 Perhaps on the missions that we send out, we will find evidence for life, 107 00:04:32,403 --> 00:04:33,855 perhaps we will not. 108 00:04:34,196 --> 00:04:37,076 And while economics may seem like an inappropriate thing 109 00:04:37,100 --> 00:04:40,868 to bring into a talk on interstellar capability, 110 00:04:40,892 --> 00:04:45,812 it is in fact one of the driving issues in achieving interstellar capability. 111 00:04:46,479 --> 00:04:50,620 You have to get things to the point where they're economically affordable 112 00:04:50,644 --> 00:04:51,914 to do what we want to do. 113 00:04:51,938 --> 00:04:53,359 So currently, 114 00:04:53,383 --> 00:04:54,909 we have systems in the lab 115 00:04:54,933 --> 00:04:59,864 which have achieved the ability to synchronize over very large scales, 116 00:04:59,888 --> 00:05:03,618 out to about 10 kilometers or roughly six miles. 117 00:05:04,367 --> 00:05:07,234 We've been able to achieve synchronization of laser systems, 118 00:05:07,258 --> 00:05:08,869 and it's worked beautifully. 119 00:05:08,893 --> 00:05:13,266 We've known how to build lasers for many decades, 120 00:05:13,290 --> 00:05:17,160 but it's only now that the technology has gotten inexpensive enough, 121 00:05:17,184 --> 00:05:18,755 and become mature enough 122 00:05:18,779 --> 00:05:23,649 that we can imagine having huge arrays, literally, 123 00:05:23,673 --> 00:05:27,299 kilometer-scale arrays, much like solar farms, 124 00:05:27,323 --> 00:05:31,685 but instead of receiving light, they transmit light. 125 00:05:31,709 --> 00:05:37,522 The beauty of this type of technology is it enables many applications, 126 00:05:37,546 --> 00:05:40,490 not just relativistic flight for small spacecraft, 127 00:05:40,514 --> 00:05:43,172 but enables high-speed spacecraft, 128 00:05:43,196 --> 00:05:45,601 high-speed flight in our solar system, 129 00:05:45,625 --> 00:05:47,458 it enables planetary defense, 130 00:05:47,482 --> 00:05:49,950 it enables space debris removal, 131 00:05:49,974 --> 00:05:55,617 it enables powering of distant assets that we may want to send power to, 132 00:05:55,641 --> 00:05:59,426 such as spacecraft or bases on the Moon or other places. 133 00:05:59,450 --> 00:06:01,633 It's an extremely versatile technology, 134 00:06:01,657 --> 00:06:04,315 it's something that humanity would want to develop 135 00:06:04,339 --> 00:06:07,466 even if they didn't want to send spacecraft to the stars, 136 00:06:07,490 --> 00:06:10,076 because that technology allows so many applications 137 00:06:10,100 --> 00:06:12,601 that are currently not feasible. 138 00:06:12,625 --> 00:06:15,267 And therefore, I feel it's an inevitable technology, 139 00:06:15,291 --> 00:06:17,355 because we have the ability, 140 00:06:17,379 --> 00:06:20,195 we just need to fine-tune the technology 141 00:06:20,219 --> 00:06:23,426 and in a sense, wait for economics to catch up with us 142 00:06:23,450 --> 00:06:26,649 so that it becomes cheap enough to build the large systems. 143 00:06:26,673 --> 00:06:29,244 The smaller systems are affordable now. 144 00:06:29,268 --> 00:06:32,704 And we've already started building prototype systems in our lab. 145 00:06:33,284 --> 00:06:35,291 So while it's not going to happen tomorrow, 146 00:06:35,315 --> 00:06:36,871 we've already begun the process, 147 00:06:36,895 --> 00:06:38,990 and so far, it's looking good. 148 00:06:39,014 --> 00:06:42,868 This is both a revolutionary program, 149 00:06:42,892 --> 00:06:46,177 in terms of being a transformative technology, 150 00:06:46,201 --> 00:06:49,137 but it's also an evolutionary program. 151 00:06:49,161 --> 00:06:52,808 So personally, I do not expect to be around 152 00:06:52,832 --> 00:06:56,698 when the first relativistic flight happens. 153 00:06:56,722 --> 00:07:00,117 I think that's probably 30-plus years off before we get to that point, 154 00:07:00,141 --> 00:07:01,712 and perhaps more. 155 00:07:01,736 --> 00:07:02,910 But what inspires me 156 00:07:02,934 --> 00:07:06,117 is to look at the ability to achieve the final goal. 157 00:07:06,141 --> 00:07:08,649 Even if it does not happen in my lifetime, 158 00:07:08,673 --> 00:07:11,537 it can happen in the lifetime of the next generation 159 00:07:11,561 --> 00:07:12,998 or the generation beyond that. 160 00:07:13,022 --> 00:07:16,099 The consequences are so transformative 161 00:07:16,123 --> 00:07:19,568 that we literally, in my opinion, must go down this path, 162 00:07:19,592 --> 00:07:21,900 and must explore what the limitations are, 163 00:07:21,924 --> 00:07:24,117 and then how do we overcome the limitations. 164 00:07:24,141 --> 00:07:25,895 The search for life on other planets 165 00:07:25,919 --> 00:07:30,100 would be one of humanity's foremost explorations, 166 00:07:30,124 --> 00:07:32,225 and if we're able to do so, 167 00:07:32,249 --> 00:07:34,645 and actually find life on another planet, 168 00:07:34,669 --> 00:07:36,756 it would change humanity forever. 169 00:07:36,780 --> 00:07:38,304 Everything is profound in life. 170 00:07:38,328 --> 00:07:39,522 If you look deep enough, 171 00:07:39,546 --> 00:07:44,427 you'll find something incredibly complex and interesting and beautiful in life. 172 00:07:45,019 --> 00:07:47,566 And the same is true with the lowly photon 173 00:07:47,590 --> 00:07:50,970 that we use to see every day. 174 00:07:51,352 --> 00:07:56,071 But when we look outside and we imagine something vastly greater, 175 00:07:56,095 --> 00:07:59,309 an array of lasers that are synchronized, 176 00:07:59,333 --> 00:08:03,472 we could imagine things which are just extraordinary in life. 177 00:08:03,496 --> 00:08:05,456 And the ability to go to another star 178 00:08:05,480 --> 00:08:08,107 is one of those extraordinary capabilities.