A Cosmologist’s Guide to the End of the Universe | Katie Mack and Debbie Millman | TED — Transcript

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1. 0:03Katie.
2. 0:04>> Yes.
3. 0:05>> Hi.
4. 0:05>> Hi.
5. 0:06>> I understand that you earned your
6. 0:09private pilot license during the
7. 0:12pandemic
8. 0:13>> Yes.
9. 0:14>> and are now doing aerobatic training.
10. 0:17I've heard of acrobatic training, but
11. 0:19never aerobatic training.
12. 0:21>> Mhm.
13. 0:21>> Tell us what that is.
14. 0:23>> Yeah, so aerobatics is flying the
15. 0:26airplane in unusual ways. So, things
16. 0:29like loops and uh spins and rolls and
17. 0:33really learning how to control the
18. 0:35airplane at all areas of the envelope.
19. 0:39You know, really beyond the normal
20. 0:41straight and level flying. And it's
21. 0:43super fun because it's like creating
22. 0:45your own roller coaster in the sky.
23. 0:47>> And it's not scary?
24. 0:49>> It's It can be scary sometimes.
25. 0:51>> a daredevil.
26. 0:52>> No, I I enjoy it because it's it's
27. 0:56challenging, it's interesting, it's a
28. 0:58different perspective, and it's a way to
29. 1:01learn enough about how the plane behaves
30. 1:03to be safer when you're trying to just
31. 1:06fly straight and level. Sometimes things
32. 1:08happen and you need to learn how to
33. 1:09recover. So, I do it because it's a
34. 1:12challenge, because I enjoy it. I'm not
35. 1:13an adrenaline junkie in any way. Um but
36. 1:16uh it's it's just something that I feel
37. 1:19like it it can make you a better pilot
38. 1:21and it's just a a different way of
39. 1:23seeing the world.
40. 1:25>> Has flying given you a different
41. 1:26perspective on your work as a
42. 1:28cosmologist?
43. 1:30>> I think what it has done is it's allowed
44. 1:33me to have a space where I don't think
45. 1:36about work, actually. It's um when you
46. 1:39are fully fully in absorbed in something
47. 1:42and fully focused, it's you you get into
48. 1:45this zone where nothing else can touch
49. 1:47you. And when you're flying, you have to
50. 1:49be focused. You can't think about other
51. 1:51things because things will go very badly
52. 1:54if you if you take your focus away from
53. 1:56what you're doing. And so, I really
54. 1:58enjoy that that opportunity to
55. 2:01just be in the moment, be in the plane,
56. 2:05have that different view of the world,
57. 2:07um and and I enjoy, you know, the extra
58. 2:10challenge of of trying to do something
59. 2:12else.
60. 2:13>> Your grandfather worked on the Apollo 11
61. 2:16mission.
62. 2:17>> Yes.
63. 2:17>> And I believed he saved the lives of the
64. 2:20Apollo 11 astronauts. Can you share some
65. 2:23of that story with us?
66. 2:24>> Yes. So, my grandfather was a
67. 2:26meteorologist in the Navy and um he
68. 2:30worked on things like um
69. 2:32creating uh satellite views of the
70. 2:34weather with these new rockets that
71. 2:37they'd just developed. And he was asked
72. 2:39to help with the Apollo 11 mission, and
73. 2:41his job was to figure out if the weather
74. 2:44conditions at the splashdown site, when
75. 2:46the capsule came back, were going to be
76. 2:48okay, right? Because you you don't want
77. 2:50to come into a storm when you're when
78. 2:52the capsule's coming in on the
79. 2:53parachutes.
80. 2:54And he was, you know, checking all the
81. 2:56usual charts, and it looked fine, but he
82. 2:58knew there was a a secret satellite that
83. 3:01was a weather satellite, but it was a
84. 3:02secret because it could also be used for
85. 3:04spying, and he had been in the Navy. Um
86. 3:06and he wanted to make sure that there
87. 3:08was nothing in the splashdown area that
88. 3:11was going to be a problem. So, he went
89. 3:12over to his connections through the Navy
90. 3:15and checked on that satellite, and it
91. 3:17turned out that the splashdown zone that
92. 3:19they'd designated had a a storm coming,
93. 3:22something called screaming eagle
94. 3:24thunderclouds. Something really bad
95. 3:26>> That doesn't sound good.
96. 3:28>> no. And apparently, it was it was bad
97. 3:31enough that it could have just ripped
98. 3:32the parachutes right off the capsule as
99. 3:34it was coming in. And so, he managed to
100. 3:36convince NASA to move the splashdown
101. 3:39site just 72 hours before the
102. 3:41splashdown, and he couldn't tell them
103. 3:43why because NASA's a civilian agency,
104. 3:45they couldn't know about these secret
105. 3:48satellites. And so, he had to just use
106. 3:51the weight of his expertise and his
107. 3:53reputation to tell them, "You have to
108. 3:55move the splashdown. I cannot tell you
109. 3:57why. Here's an alternative." And so,
110. 3:59they moved it a few hundred kilometers
111. 4:02uh in some direction, and it was fine.
112. 4:04But,
113. 4:05>> So, basically, it was a trust me, I've
114. 4:06got this.
115. 4:07>> Yeah, but they did say, "We are also
116. 4:09going to send some planes to the
117. 4:10original site, and if it's fine there,
118. 4:12you're in trouble."
119. 4:14They did send the planes. There was
120. 4:16There there was a storm,
121. 4:17um but the astronauts were were fine.
122. 4:21>> You said you were a curious child drawn
123. 4:24to the night sky before you even knew
124. 4:26the word cosmology.
125. 4:28Were you influenced by your
126. 4:29grandfather's work?
127. 4:30>> I was definitely influenced by him as a
128. 4:33scientist. So, I knew him
129. 4:35I didn't know him through his Apollo 11
130. 4:38work, because that was actually
131. 4:39classified until I was sort of an
132. 4:41adolescent, but I knew him through
133. 4:44just his expertise about the weather. Um
134. 4:47I knew him through He was a volunteer at
135. 4:49the Monterey Bay Aquarium. Uh so, he
136. 4:52knew everything about the sea animals,
137. 4:54and I I just loved to see him talk about
138. 4:56the things he was excited about. And And
139. 4:58he had gone to Caltech as a as a student
140. 5:01to learn about meteorology. And so, I I
141. 5:03I knew a little bit about Caltech and
142. 5:05about the, you know, all the nerdy
143. 5:06people there doing fun, exciting
144. 5:08science. And so, he was definitely an
145. 5:10influence in getting me excited about
146. 5:12science.
147. 5:13>> Katie, you've written about how you were
148. 5:15just 10 years old 10 years old when you
149. 5:19read Stephen Hawking's book A Brief
150. 5:21History of Time.
151. 5:22>> Mhm.
152. 5:23>> I had to read that book really, really
153. 5:26slowly to grasp what he was writing, and
154. 5:29I did that when I was 30.
155. 5:30>> Yeah. Yeah.
156. 5:32>> how did you first hear about the book
157. 5:34when you were 10 years old? And what
158. 5:36What provoked you to pick it up and
159. 5:37start reading it?
160. 5:38>> I think that I
161. 5:40you know, I had exposure to a lot of
162. 5:43different kinds of science through just
163. 5:45my my family. I think my family picked
164. 5:47up on the fact that I was curious. I was
165. 5:49always a tinkerer. I was taking things
166. 5:51apart and putting them back together,
167. 5:52you know, sometimes correctly. And I I
168. 5:54they knew that I was trying to
169. 5:56understand everything. And so I had
170. 5:58subscriptions to children's magazines
171. 6:00about science and stuff like that. And
172. 6:03um my my mom is a big science fiction um
173. 6:06fan. And so I was reading her science
174. 6:08fiction stuff. And every once in a while
175. 6:10there would be like a public talk about
176. 6:12science somewhere in our area. We lived
177. 6:14in the LA area. And so she'd take me to
178. 6:16talks by scientists. And so I think I
179. 6:18just kind of accumulated um some of
180. 6:21those books. And and uh when I read
181. 6:24Hawking's book, I didn't understand very
182. 6:25much of it as a 10-year-old, but I knew
183. 6:28>> you reading it then?
184. 6:29>> I just wanted to know. I just really I
185. 6:31really wanted to try to understand this
186. 6:33stuff. And I thought, you know, if I
187. 6:34keep studying, I'll I'll I'll get this.
188. 6:37And I'll I'll maybe be able to work in
189. 6:39this area. I didn't know before I read
190. 6:40that book that you could be a
191. 6:42cosmologist, you know. I saw that
192. 6:43Stephen Hawking is called a cosmologist.
193. 6:45I was like, you know, what is that? What
194. 6:47is that work? And I thought, well,
195. 6:49that's what I want to do. I want to
196. 6:50study the universe. I want to study the
197. 6:52Big Bang and black holes and and
198. 6:54space-time. I thought that sounded
199. 6:56really cool.
200. 6:57>> You attended Caltech for your undergrad
201. 6:59education and graduated with a degree in
202. 7:01physics. And you said that theoretical
203. 7:03physics is not just a discipline of a of
204. 7:07equations,
205. 7:08>> Mhm.
206. 7:08>> but of imagination.
207. 7:10>> Yeah. Yeah.
208. 7:10>> Um how so?
209. 7:11>> You know, theoretical physics in general
210. 7:14is the attempt to create kind of a
211. 7:16mathematical cartoon of the world. So,
212. 7:19you know, we have certain observations,
213. 7:21we get data, and we try to find a a way
214. 7:25to connect that data to whatever the
215. 7:27input was. And and so we build sort of
216. 7:30mathematical machine as a way to figure
217. 7:32out how that all fits together. And you
218. 7:34have to be creative. You have to, you
219. 7:36know, think about like, what are the
220. 7:38possibilities here? What are the things,
221. 7:40you know, what kinds of symmetries can I
222. 7:42find in this system, you know, how do
223. 7:44how are the these things similar to
224. 7:45these other things? So, it's very
225. 7:47creative, it's very interactive, you
226. 7:48know, there's the theoretical physics
227. 7:50community is extremely collaborative,
228. 7:52you know, everybody's gathered around
229. 7:54chalkboards arguing about equations and,
230. 7:57you know, going to conferences all the
231. 7:58time giving talks, you know, we don't we
232. 8:00don't sit in isolation, you know, just
233. 8:03writing down equations by ourselves.
234. 8:04It's it's always a conversation and it's
235. 8:07always it's it's it's very much a
236. 8:09creative, imaginative kind of work.
237. 8:12>> You went on to Princeton University for
238. 8:14your PhD, where your doctoral research
239. 8:17focused on early universe cosmology,
240. 8:21cosmic inflation, and dark matter. And
241. 8:24you've written about how much of
242. 8:26cosmology is trying to tell a story from
243. 8:30the faintest traces of light.
244. 8:32>> Mhm.
245. 8:33>> Katie, how are you able to decipher
246. 8:35those earliest traces? And what are some
247. 8:39of the most important things you've
248. 8:40learned about that light?
249. 8:42>> Yeah, so, um, I think in that in that I
250. 8:45must have been talking about the cosmic
251. 8:46microwave background, which is light
252. 8:48that's all around us in the universe.
253. 8:50Um, if you if you tune a a microwave
254. 8:53receiver, so, microwaves are just a kind
255. 8:55of light, a kind of electromagnetic
256. 8:57radiation. Um, and if you tune your
257. 8:59receiver to the right frequencies, you
258. 9:01can see this background of just a glow
259. 9:04all around you everywhere in space. And,
260. 9:07um, that's the light from the Big Bang.
261. 9:10And and the way that we know that what
262. 9:11that is is that we can look at the
263. 9:13spectrum of that light, how much energy
264. 9:14is at different frequencies, and we can
265. 9:16see that the spectrum is exactly the
266. 9:19same spectrum you get when something is
267. 9:21glowing because it's hot. Like, if you
268. 9:22take a poker and you stick it in the
269. 9:24fire, it glows red, and that has a
270. 9:26certain spectrum, a certain distribution
271. 9:28of light. And it's just anything you
272. 9:31heat up that glows, it glows because
273. 9:33it's hot, it's because of the way the
274. 9:35particles are moving around and creating
275. 9:37light. And this background light has
276. 9:39exactly the same spectrum and is
277. 9:40everywhere in space. And so what it is
278. 9:42is is if you look far enough away in any
279. 9:44direction, you're looking so far away
280. 9:47that the light has taken a really long
281. 9:48time to get to you. Um you know, light
282. 9:50takes some time to travel. So, you know,
283. 9:52even in this room, you know, you're
284. 9:54maybe 6 ft away from me. It takes about
285. 9:566 nanoseconds for the light to get from
286. 9:58you to me. So, you're you're 6
287. 10:00nanoseconds in the past to me.
288. 10:01>> And you are to me.
289. 10:02>> And you and I am to you. But if I look
290. 10:04far enough out in the cosmos, I can look
291. 10:06billions of years in the past and I'm
292. 10:08seeing directly that the past. And if
293. 10:11you look so far away that you're looking
294. 10:1313.8 billion years ago, you're looking
295. 10:16at the time when the whole universe was
296. 10:18glowing with heat because it was in this
297. 10:20this hot dense phase of the very early
298. 10:22universe. And so you see that glow very
299. 10:25directly in the cosmic microwave
300. 10:27background. And that's that's something
301. 10:29that we can study. We can study that
302. 10:31glow because we are looking directly at
303. 10:33the very very early universe. It's
304. 10:34incredible.
305. 10:36>> Given that light travels, the light that
306. 10:39is being picked up in this background,
307. 10:43where is that going?
308. 10:44>> It's it's just it's just diffusing
309. 10:46through space. So, it's going in every
310. 10:48direction.
311. 10:48>> So, it's just continually moving.
312. 10:50>> Yeah. Yeah. So, if you turn on a light
313. 10:52bulb, the light moves out in every
314. 10:54direction and you know, the light from
315. 10:57the the the time the whole universe was
316. 10:59glowing with heat, you know, that light
317. 11:01was just moving in every direction.
318. 11:03Eventually, the universe cooled down and
319. 11:05light, you know, kept traveling in every
320. 11:06direction and the places we see it at
321. 11:09the sort of edges of our vision in the
322. 11:11universe, that light is also going away
323. 11:13from us. But the part that's going
324. 11:14toward us, we see and we see that that
325. 11:16background radiation.
326. 11:18>> Voyager is not even one full light day
327. 11:23away from Earth.
328. 11:25But it's going to be another 40,000
329. 11:28years before it encounters another
330. 11:31celestial body.
331. 11:33>> Yeah.
332. 11:34>> Cosmology often deals with scales that
333. 11:37defy comprehension. How do you hold on
334. 11:41to the human scale with this sort of
335. 11:44infinite, what seems like it's infinite?
336. 11:47>> I mean, I can't conceptualize these
337. 11:49scales really any more than anyone else
338. 11:52can, you know, what we we talk about,
339. 11:54you know, billions of light years and
340. 11:57and all this stuff and and I I just have
341. 12:00to write down the number and trust it. I
342. 12:01don't I don't have a sense, you know, I
343. 12:03can't hold in my head this this notion
344. 12:05of, you know, that much space or that
345. 12:07much time. Um so for me, you know,
346. 12:11there's there's a kind of
347. 12:14you know, sort of a a ruler in my mind
348. 12:16of, you know, million, billion, trillion
349. 12:19and I don't have a sense for how far
350. 12:20apart those are. I just know that these
351. 12:22are the scales that I'm working with and
352. 12:24then I I think about on the human scale,
353. 12:27you know, what what I can do as a as a
354. 12:29scientist to try to understand it, but
355. 12:31um you know, my work on my in my work
356. 12:34even even individual galaxies are are
357. 12:36not that important.
358. 12:37>> [laughter]
359. 12:39>> Let alone us.
360. 12:41>> Yeah, I mean, professionally I I you
361. 12:44know, all the human stuff is kind of
362. 12:46lost in the weeds. Um but but the the
363. 12:49work itself is is very human because
364. 12:51we're all working together and we're all
365. 12:53having this continual conversation and
366. 12:55the mathematical models we're building
367. 12:57are very much tied to our humanity
368. 12:58because these are, you know, just things
369. 13:02that come out of our our imaginations
370. 13:03that are tested with the data and we are
371. 13:06constantly making choices and
372. 13:07constantly, you know, trying to better
373. 13:09understand the universe we live in.
374. 13:12>> What provoked you to choose a field that
375. 13:17is primarily about how we end?
376. 13:21>> [laughter]
377. 13:22>> Um so
378. 13:24I'm really interested in the whole story
379. 13:26of the universe. So I've done a lot of
380. 13:28work about the beginning of the universe
381. 13:30and I've worked on how the universe
382. 13:32evolves over time, how the first stars
383. 13:34formed, how the dark matter, this
384. 13:36invisible stuff that holds galaxies
385. 13:37together, how that's evolved over time
386. 13:39and brought galaxies into existence. And
387. 13:43at some point I started getting really
388. 13:44curious about the end as well and
389. 13:46I just, you know, we know the universe
390. 13:48is evolving and changing and we know
391. 13:50that it's not going to be the same
392. 13:51forever. It's going to be different and
393. 13:53it's it's
394. 13:55we we know that there was it was
395. 13:57different in the beginning and it's
396. 13:58changing and it's going to be real
397. 13:59different in the future. And so, I'm
398. 14:01really curious what that ending looks
399. 14:03like and so that's why I wrote a book
400. 14:05about the end of the universe just cuz
401. 14:06I'm I wanted to talk about, you know,
402. 14:09what are the possibilities? What are we
403. 14:11thinking about how the universe will end
404. 14:13and like what is that whole story, you
405. 14:15know? I When you read a story, you want
406. 14:17to know the beginning, the middle, and
407. 14:19the end and and you know, I feel like
408. 14:22it's it's really part of how we fit into
409. 14:24this cosmos.
410. 14:26>> Your book is titled The End of
411. 14:27Everything and in it you explore five
412. 14:31possible endings for the cosmos. The Big
413. 14:34Crunch, Heat Death, The Big Rip, Vacuum
414. 14:37Decay, and Bounce. Were there others
415. 14:40that you left out or is this the only
416. 14:42five options?
417. 14:44>> Um [laughter]
418. 14:46So, I focus on sort of five categories
419. 14:48of endings that are things that are
420. 14:51actually talked about in the physics
421. 14:53literature. So, all of these are
422. 14:54possibilities that physicists have put
423. 14:56together models, we've
424. 14:59you know, worked out what what the
425. 15:01physics would be in each of these
426. 15:02scenarios.
427. 15:04There are there are ways to to tweak
428. 15:07each of these where they're going to be
429. 15:08a little bit different, but basically,
430. 15:11you know, in terms of the whole cosmos,
431. 15:13there there are only a finite number of
432. 15:15ways that it can be destroyed,
433. 15:17>> [laughter]
434. 15:18>> like it can it can collapse, it can keep
435. 15:19going,
436. 15:21you can have these weird transitions
437. 15:22where there's basically a bubble of
438. 15:25of a new kind of space that spreads
439. 15:26through the universe and destroys
440. 15:27everything. And then there's like cyclic
441. 15:29models and that's
442. 15:31and there are a lot of different ways
443. 15:32where the universe can end and start
444. 15:34again or or the beginning of our
445. 15:35universe could be the end of a previous
446. 15:37universe and there are are a few of
447. 15:39those that I talk about in the book as
448. 15:40well.
449. 15:41>> that that to me feels the most hopeful.
450. 15:44Um
451. 15:45>> [laughter]
452. 15:46>> You've said that writing this book
453. 15:48changed your relationship to time.
454. 15:52>> Yeah.
455. 15:52>> In what way?
456. 15:54>> You know, talking about the very very
457. 15:56distant future of the universe, you you
458. 15:58really think about this kind of deep
459. 16:00time idea and and how
460. 16:03you know, the the bit of time we live in
461. 16:06is so small. Um and the the bit of time
462. 16:09humanity has existed in is so small and
463. 16:11and there's there was time before us and
464. 16:13there's going to be so much time after
465. 16:15us.
466. 16:16Um and it made me think a lot about not
467. 16:18just time but like
468. 16:20how our impact on the world, you know,
469. 16:23we we are really unimportant in the
470. 16:25universe. Just to say [laughter] like
471. 16:27like uh humanity is is completely
472. 16:31insignificant in the cosmos in every
473. 16:32possible way you can imagine. Um
474. 16:34but uh
475. 16:35>> Optimistic morning, folks.
476. 16:37>> I mean, but you know, I mean,
477. 16:39we are it's impressive that we know so
478. 16:41much but even though we are so
479. 16:42insignificant. Um
480. 16:44but uh you know, it made me think about
481. 16:45like
482. 16:47you know, everything is is going to end
483. 16:49at some point and there's not going to
484. 16:51be some you know, final thing that makes
485. 16:53it all worthwhile, right? At some point
486. 16:56everything will be destroyed. It kind of
487. 16:57won't have mattered that we were here.
488. 16:59Um so when we have think about how to
489. 17:01find meaning and purpose, it's
490. 17:04you know, it has to be something that's
491. 17:06self-contained, you know, something that
492. 17:08exists in the universe now. And what is
493. 17:11you know, how do we find meaning in the
494. 17:12moment? How do we find meaning that
495. 17:13doesn't depend on it all being wrapped
496. 17:16up with a tidy bow, you know, at some
497. 17:18future point. Um and that that really
498. 17:20made me think differently about what's
499. 17:22important in my life, um what to be
500. 17:25upset about or not upset about, um
501. 17:27because, you know, we are we are just
502. 17:30temporary and we are doing the best we
503. 17:31can while we're here.
504. 17:33>> Katie, in addition to your work in
505. 17:35theoretical astrophysics, cosmology,
506. 17:39writing, and aerial acrobatics, um
507. 17:43you're also a poet.
508. 17:45>> [laughter]
509. 17:45>> I've I've done a little bit of poetry,
510. 17:47yeah. I I enjoy that.
511. 17:48>> I I'm wondering if it's possible I know
512. 17:51I know we talked a little bit about this
513. 17:52ahead of time, but my TED friends and I
514. 17:55asked if you would read one of your
515. 17:56poems today on the TED next stage and
516. 18:00you agreed.
517. 18:01>> Yeah.
518. 18:01>> Um
519. 18:02how lucky are we?
520. 18:04Um so, can you tell us a little bit
521. 18:06about what you're going to share with us
522. 18:07today?
523. 18:08>> So, I've written a few things here and
524. 18:10there. I've done a lot of science
525. 18:11writing. I've written a few poems. Um
526. 18:12and at some point I was contacted by a
527. 18:15sort of graphic uh design company saying
528. 18:17that they were putting together a sort
529. 18:18of reel of their um
530. 18:21their work and they wanted uh they
531. 18:22wanted a poem they wanted to create a
532. 18:24you know, have a poem to go along with
533. 18:26it and could I write a poem about
534. 18:27something science-y and then they would
535. 18:28illustrate it. They they were called
536. 18:30Finger Industries, now they're called
537. 18:31Ouch Ouch Health. Um and uh and so I
538. 18:34wrote this poem for for their
539. 18:37the their sort of demo reel.
540. 18:39>> Cool. Wonderful. Would it be okay for
541. 18:40you to stand?
542. 18:41>> Sure, sure.
543. 18:41>> Excellent. Thank you.
544. 18:42>> Okay.
545. 18:44So, the poem is called Constructs.
546. 18:47What do you see when you look at the
547. 18:49world?
548. 18:50At this infinite variety of objects,
549. 18:54colors, textures, weights, flavors.
550. 18:58What makes each person, animal, object
551. 19:02unique,
552. 19:04special?
553. 19:06There are around 90 chemical elements
554. 19:08naturally found on this planet.
555. 19:11But each one
556. 19:12hydrogen, oxygen, or carbon
557. 19:16is just a construct.
558. 19:18A tiny, shivering mass of the same
559. 19:22protons, neutrons, and electrons
560. 19:26found in any other.
561. 19:28Same ingredients,
562. 19:30different recipe.
563. 19:33We are not essentially our constituent
564. 19:35parts.
565. 19:37We are the knowledge that unites them.
566. 19:41>> Katie Mack.
567. 19:42>> [applause]
568. 19:43>> Thank you so much.