WEBVTT 00:00:00.902 --> 00:00:06.880 Doc Edgerton inspired us with awe and curiosity 00:00:06.880 --> 00:00:12.142 with this photo of a bullet piercing through an apple, 00:00:12.142 --> 00:00:17.020 and exposure just a millionth of a second. 00:00:17.020 --> 00:00:24.327 But now, 50 years later, we can go a million times faster 00:00:24.327 --> 00:00:27.923 and see the world not at a million, 00:00:27.923 --> 00:00:29.733 or a billion, 00:00:29.733 --> 00:00:33.168 but one trillion frames per second. NOTE Paragraph 00:00:33.168 --> 00:00:37.553 I present you a new type of photography, 00:00:37.553 --> 00:00:39.612 femto-photography, 00:00:39.612 --> 00:00:44.212 a new imaging technique so fast 00:00:44.212 --> 00:00:49.413 that it can create slow motion videos of light in motion. 00:00:49.413 --> 00:00:52.151 And with that, we can create cameras 00:00:52.151 --> 00:00:54.296 that can look around corners, 00:00:54.296 --> 00:00:56.293 beyond line of sight 00:00:56.293 --> 00:01:00.686 or see inside our body without an X-ray, 00:01:00.686 --> 00:01:06.087 and really challenge what we mean by a camera. NOTE Paragraph 00:01:06.087 --> 00:01:09.598 Now if I take a laser pointer and turn it on and off 00:01:09.598 --> 00:01:12.425 in one trillionth of a second -- 00:01:12.425 --> 00:01:15.237 which is several femtoseconds -- 00:01:15.237 --> 00:01:17.517 I'll create a packet of photons 00:01:17.517 --> 00:01:19.867 barely a millimeter wide, 00:01:19.867 --> 00:01:22.793 and that packet of photons, that bullet, 00:01:22.793 --> 00:01:24.743 will travel at the speed of light, 00:01:24.743 --> 00:01:29.251 and, again, a million times faster than an ordinary bullet. 00:01:29.251 --> 00:01:34.157 Now, if you take that bullet and take this packet of photons 00:01:34.157 --> 00:01:37.330 and fire into this bottle, 00:01:37.330 --> 00:01:41.864 how will those photons shatter into this bottle? 00:01:41.864 --> 00:01:46.088 How does light look in slow motion? NOTE Paragraph 00:02:06.041 --> 00:02:09.699 Now, the whole event -- (Applause) 00:02:09.699 --> 00:02:13.918 (Applause) NOTE Paragraph 00:02:13.918 --> 00:02:16.521 Now, remember, the whole event 00:02:16.521 --> 00:02:19.904 is effectively taking place in less than a nanosecond 00:02:19.904 --> 00:02:22.240 — that's how much time it takes for light to travel — 00:02:22.240 --> 00:02:26.740 but I'm slowing down in this video by a factor of 10 billion 00:02:26.740 --> 00:02:30.413 so you can see the light in motion. NOTE Paragraph 00:02:30.413 --> 00:02:35.034 But, Coca-Cola did not sponsor this research. (Laughter) NOTE Paragraph 00:02:35.034 --> 00:02:37.081 Now, there's a lot going on in this movie, 00:02:37.081 --> 00:02:39.443 so let me break this down and show you what's going on. 00:02:39.443 --> 00:02:42.683 So, the pulse enters the bottle, our bullet, 00:02:42.683 --> 00:02:45.245 with a packet of photons that start traveling through 00:02:45.245 --> 00:02:47.082 and that start scattering inside. 00:02:47.082 --> 00:02:49.313 Some of the light leaks, goes on the table, 00:02:49.313 --> 00:02:52.100 and you start seeing these ripples of waves. 00:02:52.100 --> 00:02:54.981 Many of the photons eventually reach the cap 00:02:54.981 --> 00:02:57.895 and then they explode in various directions. 00:02:57.895 --> 00:02:59.807 As you can see, there's a bubble of air, 00:02:59.807 --> 00:03:01.473 and it's bouncing around inside. 00:03:01.473 --> 00:03:03.947 Meanwhile, the ripples are traveling on the table, 00:03:03.947 --> 00:03:05.816 and because of the reflections at the top, 00:03:05.816 --> 00:03:09.450 you see at the back of the bottle, after several frames, 00:03:09.450 --> 00:03:12.352 the reflections are focused. NOTE Paragraph 00:03:12.352 --> 00:03:18.246 Now, if you take an ordinary bullet 00:03:18.246 --> 00:03:21.647 and let it go the same distance and slow down the video 00:03:21.647 --> 00:03:24.196 again by a factor of 10 billion, do you know 00:03:24.196 --> 00:03:29.921 how long you'll have to sit here to watch that movie? 00:03:29.921 --> 00:03:34.309 A day, a week? Actually, a whole year. 00:03:34.309 --> 00:03:38.223 It'll be a very boring movie — (Laughter) — 00:03:38.223 --> 00:03:42.275 of a slow, ordinary bullet in motion. NOTE Paragraph 00:03:42.275 --> 00:03:46.878 And what about some still-life photography? NOTE Paragraph 00:03:52.770 --> 00:03:58.122 You can watch the ripples again washing over the table, 00:03:58.122 --> 00:04:01.035 the tomato and the wall in the back. 00:04:01.035 --> 00:04:05.259 It's like throwing a stone in a pond of water. NOTE Paragraph 00:04:07.197 --> 00:04:11.087 I thought, this is how nature paints a photo, 00:04:11.087 --> 00:04:13.674 one femto frame at a time, 00:04:13.674 --> 00:04:19.066 but of course our eye sees an integral composite. 00:04:19.066 --> 00:04:22.192 But if you look at this tomato one more time, 00:04:22.192 --> 00:04:24.708 you will notice, as the light washes over the tomato, 00:04:24.708 --> 00:04:27.599 it continues to glow. It doesn't become dark. 00:04:27.599 --> 00:04:31.147 Why is that? Because the tomato is actually ripe, 00:04:31.147 --> 00:04:33.248 and the light is bouncing around inside the tomato, 00:04:33.248 --> 00:04:37.714 and it comes out after several trillionths of a second. 00:04:37.714 --> 00:04:40.347 So, in the future, when this femto-camera 00:04:40.347 --> 00:04:42.439 is in your camera phone, 00:04:42.439 --> 00:04:44.149 you might be able to go to a supermarket 00:04:44.149 --> 00:04:48.189 and check if the fruit is ripe without actually touching it. NOTE Paragraph 00:04:48.189 --> 00:04:53.519 So how did my team at MIT create this camera? 00:04:53.519 --> 00:04:55.486 Now, as photographers, you know, 00:04:55.486 --> 00:04:59.547 if you take a short exposure photo, you get very little light, 00:04:59.547 --> 00:05:01.753 but we're going to go a billion times faster 00:05:01.753 --> 00:05:03.609 than your shortest exposure, 00:05:03.609 --> 00:05:05.409 so you're going to get hardly any light. 00:05:05.409 --> 00:05:07.252 So, what we do is we send that bullet, 00:05:07.252 --> 00:05:09.801 those packet of photons, millions of times, 00:05:09.801 --> 00:05:12.908 and record again and again with very clever synchronization, 00:05:12.908 --> 00:05:14.999 and from the gigabytes of data, 00:05:14.999 --> 00:05:17.115 we computationally weave together 00:05:17.115 --> 00:05:20.580 to create those femto-videos I showed you. NOTE Paragraph 00:05:20.580 --> 00:05:23.120 And we can take all that raw data 00:05:23.120 --> 00:05:26.015 and treat it in very interesting ways. 00:05:26.015 --> 00:05:27.856 So, Superman can fly. 00:05:27.856 --> 00:05:30.318 Some other heroes can become invisible, 00:05:30.318 --> 00:05:35.416 but what about a new power for a future superhero: 00:05:35.416 --> 00:05:37.914 to see around corners? 00:05:37.914 --> 00:05:42.587 The idea is that we could shine some light on the door. 00:05:42.587 --> 00:05:45.262 It's going to bounce, go inside the room, 00:05:45.262 --> 00:05:47.692 some of that is going to reflect back on the door, 00:05:47.692 --> 00:05:49.199 and then back to the camera, 00:05:49.199 --> 00:05:52.687 and we could exploit these multiple bounces of light. NOTE Paragraph 00:05:52.687 --> 00:05:55.084 And it's not science fiction. We have actually built it. 00:05:55.084 --> 00:05:57.468 On the left, you see our femto-camera. 00:05:57.468 --> 00:05:59.847 There's a mannequin hidden behind a wall, 00:05:59.847 --> 00:06:02.829 and we're going to bounce light off the door. NOTE Paragraph 00:06:02.829 --> 00:06:04.777 So after our paper was published 00:06:04.777 --> 00:06:06.711 in Nature Communications, 00:06:06.711 --> 00:06:08.626 it was highlighted by Nature.com, 00:06:08.626 --> 00:06:11.189 and they created this animation. NOTE Paragraph 00:06:11.189 --> 00:06:17.591 (Music) NOTE Paragraph 00:06:17.591 --> 00:06:21.052 We're going to fire those bullets of light, 00:06:21.052 --> 00:06:24.315 and they're going to hit this wall, 00:06:24.315 --> 00:06:26.970 and because the packet of the photons, 00:06:26.970 --> 00:06:29.267 they will scatter in all the directions, 00:06:29.267 --> 00:06:31.515 and some of them will reach our hidden mannequin, 00:06:31.515 --> 00:06:34.394 which in turn will again scatter that light, 00:06:34.394 --> 00:06:38.080 and again in turn the door will reflect 00:06:38.080 --> 00:06:40.152 some of that scattered light, 00:06:40.152 --> 00:06:42.896 and a tiny fraction of the photons will actually 00:06:42.896 --> 00:06:45.180 come back to the camera, but most interestingly, 00:06:45.180 --> 00:06:48.926 they will all arrive at a slightly different time slot. 00:06:48.926 --> 00:06:53.503 (Music) NOTE Paragraph 00:06:53.503 --> 00:06:56.320 And because we have a camera that can run so fast, 00:06:56.320 --> 00:06:59.426 our femto-camera, it has some unique abilities. 00:06:59.426 --> 00:07:02.332 It has very good time resolution, 00:07:02.332 --> 00:07:05.850 and it can look at the world at the speed of light. 00:07:05.850 --> 00:07:09.395 And this way, we know the distances, of course to the door, 00:07:09.395 --> 00:07:11.289 but also to the hidden objects, 00:07:11.289 --> 00:07:12.884 but we don't know which point corresponds 00:07:12.884 --> 00:07:15.206 to which distance. 00:07:15.206 --> 00:07:18.446 (Music) NOTE Paragraph 00:07:18.446 --> 00:07:22.390 By shining one laser, we can record one raw photo, which, 00:07:22.390 --> 00:07:24.840 you look on the screen, doesn't really make any sense, 00:07:24.840 --> 00:07:26.720 but then we will take a lot of such pictures, 00:07:26.720 --> 00:07:29.139 dozens of such pictures, put them together, 00:07:29.139 --> 00:07:31.817 and try to analyze the multiple bounces of light, 00:07:31.817 --> 00:07:35.233 and from that, can we see the hidden object? 00:07:35.233 --> 00:07:38.152 Can we see it in full 3D? NOTE Paragraph 00:07:38.152 --> 00:07:40.788 So this is our reconstruction. (Music) 00:07:40.788 --> 00:07:44.246 (Music) 00:07:44.246 --> 00:07:52.554 (Music) (Applause) NOTE Paragraph 00:07:52.554 --> 00:07:55.165 Now we have some ways to go before we take this 00:07:55.165 --> 00:07:58.362 outside the lab on the road, but in the future, 00:07:58.362 --> 00:08:01.196 we could create cars that avoid collisions 00:08:01.196 --> 00:08:03.412 with what's around the bend, 00:08:03.412 --> 00:08:07.326 or we can look for survivors in hazardous conditions 00:08:07.326 --> 00:08:11.604 by looking at light reflected through open windows, 00:08:11.604 --> 00:08:14.229 or we can build endoscopes that can see 00:08:14.229 --> 00:08:17.499 deep inside the body around occluders, 00:08:17.499 --> 00:08:19.375 and also for cardioscopes. 00:08:19.375 --> 00:08:21.876 But of course, because of tissue and blood, 00:08:21.876 --> 00:08:24.063 this is quite challenging, so this is really a call 00:08:24.063 --> 00:08:26.916 for scientists to start thinking about femto-photography 00:08:26.916 --> 00:08:29.505 as really a new imaging modality to solve 00:08:29.505 --> 00:08:33.082 the next generation of health imaging problems. NOTE Paragraph 00:08:33.082 --> 00:08:36.963 Now, like Doc Edgerton, a scientist himself, 00:08:36.963 --> 00:08:42.139 science became art, an art of ultra-fast photography, 00:08:42.139 --> 00:08:45.603 and I realized that all the gigabytes of data 00:08:45.603 --> 00:08:47.607 that we're collecting every time 00:08:47.607 --> 00:08:51.050 is not just for scientific imaging, but we can also do 00:08:51.050 --> 00:08:54.830 a new form of computational photography 00:08:54.830 --> 00:08:58.969 with time-lapse and color-coding, 00:08:58.969 --> 00:09:01.739 and we look at those ripples. Remember, 00:09:01.739 --> 00:09:04.414 the time between each of those ripples is only 00:09:04.414 --> 00:09:08.757 a few trillionths of a second. NOTE Paragraph 00:09:08.757 --> 00:09:10.713 But there's also something funny going on here. 00:09:10.713 --> 00:09:13.067 When you look at the ripples under the cap, 00:09:13.067 --> 00:09:16.687 the ripples are moving away from us. 00:09:16.687 --> 00:09:18.836 The ripples should be moving towards us. 00:09:18.836 --> 00:09:20.603 What's going on here? NOTE Paragraph 00:09:20.603 --> 00:09:22.561 It turns out, because we're recording 00:09:22.561 --> 00:09:27.108 nearly at the speed of light, 00:09:27.108 --> 00:09:29.178 we have strange effects, 00:09:29.178 --> 00:09:33.209 and Einstein would have loved to see this picture. 00:09:33.209 --> 00:09:36.478 The order at which events take place in the world 00:09:36.478 --> 00:09:41.046 appear in the camera with sometimes reversed order, 00:09:41.046 --> 00:09:44.405 so by applying the corresponding space and time warp, 00:09:44.405 --> 00:09:48.450 we can correct for this distortion. NOTE Paragraph 00:09:48.450 --> 00:09:52.691 So whether it's for photography around corners, 00:09:52.691 --> 00:09:56.999 or creating the next generation of health imaging, 00:09:56.999 --> 00:09:59.679 or creating new visualizations, 00:09:59.679 --> 00:10:03.238 since our invention, we have open-sourced 00:10:03.238 --> 00:10:06.937 all the data and details on our website, and our hope 00:10:06.937 --> 00:10:13.573 is that the DIY, the creative and the research community 00:10:13.573 --> 00:10:17.376 will show us that we should stop obsessing about 00:10:17.376 --> 00:10:20.616 the megapixels in cameras — (Laughter) — 00:10:20.616 --> 00:10:25.646 and start focusing on the next dimension in imaging. 00:10:25.646 --> 00:10:30.180 It's about time. Thank you. (Applause) 00:10:30.180 --> 00:10:40.385 (Applause)