1 00:00:05,360 --> 00:00:09,440 Speaker 1: Although every cell in your body changes such that you 2 00:00:09,520 --> 00:00:14,440 Speaker 1: are never again the same person physically, and your neural 3 00:00:14,480 --> 00:00:17,639 Speaker 1: networks change every hour of your life as you absorb 4 00:00:17,760 --> 00:00:23,200 Speaker 1: new experiences. Why do you have an illusion of consistency, 5 00:00:23,360 --> 00:00:26,840 Speaker 1: as though you're the same person you were a week 6 00:00:26,880 --> 00:00:29,800 Speaker 1: ago or a year ago. What does this have to 7 00:00:29,840 --> 00:00:35,240 Speaker 1: do with the mythical watercraft of the Greek demigod Theseus? 8 00:00:35,320 --> 00:00:39,360 Speaker 1: What is the end of history illusion? And why do 9 00:00:39,440 --> 00:00:42,960 Speaker 1: you go through so much trouble to make things comfortable 10 00:00:43,159 --> 00:00:46,839 Speaker 1: for your future self even though you don't know that 11 00:00:46,960 --> 00:00:50,120 Speaker 1: person and you can be guaranteed that that person is 12 00:00:50,159 --> 00:00:52,600 Speaker 1: not going to feel the same way you do now. 13 00:00:53,400 --> 00:00:57,360 Speaker 1: And if there were an afterlife, what age would your 14 00:00:57,480 --> 00:01:04,880 Speaker 1: deity dial you to for living out eternity? Welcome to 15 00:01:04,920 --> 00:01:08,319 Speaker 1: Inner Cosmos with me David Eagleman. I'm a neuroscientist and 16 00:01:08,360 --> 00:01:12,119 Speaker 1: an author at Stanford and in these episodes we dive 17 00:01:12,200 --> 00:01:15,560 Speaker 1: deeply into our three pound universe to uncover some of 18 00:01:15,600 --> 00:01:30,080 Speaker 1: the most surprising aspects of our lives. Today, we're going 19 00:01:30,120 --> 00:01:33,440 Speaker 1: to talk about the notion of having a self and 20 00:01:33,560 --> 00:01:36,520 Speaker 1: what that has to do with our memory. And this 21 00:01:36,560 --> 00:01:38,200 Speaker 1: is a big topic, so we're going to do this 22 00:01:38,360 --> 00:01:41,920 Speaker 1: in two parts. Today, we're going to talk about how 23 00:01:41,959 --> 00:01:45,679 Speaker 1: and why we think of ourselves as lasting through time 24 00:01:46,120 --> 00:01:48,560 Speaker 1: and what that has to do with our memories. And 25 00:01:48,760 --> 00:01:51,559 Speaker 1: in next week's episode, part two, I'm going to talk 26 00:01:51,600 --> 00:01:55,320 Speaker 1: with my colleague, neuroscientist Michael Levin, one of the most 27 00:01:55,520 --> 00:01:58,600 Speaker 1: energized and original thinkers in the field, and I'm going 28 00:01:58,640 --> 00:02:00,840 Speaker 1: to talk with him about the way in which memories 29 00:02:00,880 --> 00:02:04,040 Speaker 1: can be thought of like little creatures of their own 30 00:02:04,240 --> 00:02:08,280 Speaker 1: that carry messages in a bottle from one version of 31 00:02:08,320 --> 00:02:12,040 Speaker 1: you to the next. So for today, let's start in 32 00:02:12,160 --> 00:02:16,800 Speaker 1: ancient Greece, where the historian Blutarch wrote about a tough 33 00:02:16,880 --> 00:02:20,799 Speaker 1: puzzle that had been floating around in the Greek philosopher circles, 34 00:02:20,840 --> 00:02:24,600 Speaker 1: and they were all arguing about it. The puzzle was this, 35 00:02:25,280 --> 00:02:30,240 Speaker 1: imagine the ship of Theseus. Theseus was the hero in 36 00:02:30,240 --> 00:02:33,160 Speaker 1: Greek mythology who slayed the minotaur. The idea is that 37 00:02:33,320 --> 00:02:37,160 Speaker 1: Theseus and his crew of Athenians sail back from Crete 38 00:02:37,520 --> 00:02:41,720 Speaker 1: and dock his wonderful ship. But then the ship sits 39 00:02:41,760 --> 00:02:44,720 Speaker 1: in harbor for a long time and one of the 40 00:02:44,760 --> 00:02:48,920 Speaker 1: planks starts to rot, so it gets replaced with new 41 00:02:48,960 --> 00:02:52,359 Speaker 1: and stronger timber, and then that happens with another plank 42 00:02:52,400 --> 00:02:56,200 Speaker 1: on the ship, and another, and eventually, with enough time, 43 00:02:56,680 --> 00:03:00,800 Speaker 1: the entire ship gets replaced, meaning that not a single 44 00:03:00,880 --> 00:03:03,640 Speaker 1: plank is the same as what it was when the 45 00:03:03,720 --> 00:03:07,600 Speaker 1: ship first docked. And the question is is it the 46 00:03:07,639 --> 00:03:11,760 Speaker 1: same ship of Theseus or is it not his ship anymore? 47 00:03:11,840 --> 00:03:16,720 Speaker 1: Because every single part has been replaced. Plutarch suggested that 48 00:03:16,800 --> 00:03:19,720 Speaker 1: half the philosophers in Greece argue the ship is still 49 00:03:19,720 --> 00:03:23,840 Speaker 1: the same ship because it retains its identity despite the 50 00:03:23,919 --> 00:03:27,160 Speaker 1: changes to its parts, and the other half of philosophers 51 00:03:27,200 --> 00:03:30,280 Speaker 1: he suggested, argued that the ship is not the same 52 00:03:30,320 --> 00:03:33,320 Speaker 1: ship because no part of it is the same. So 53 00:03:33,919 --> 00:03:37,680 Speaker 1: for thousands of years, the Ship of Theseus has been 54 00:03:37,720 --> 00:03:42,640 Speaker 1: a thought experiment that surfaces these tough questions about identity 55 00:03:42,720 --> 00:03:46,040 Speaker 1: and change. By the way, there are lots of variants 56 00:03:46,160 --> 00:03:49,200 Speaker 1: on this. My father had an axe in the garage, 57 00:03:49,400 --> 00:03:51,160 Speaker 1: and he would always hold it up and tell me 58 00:03:51,720 --> 00:03:56,000 Speaker 1: this was actually George Washington's axe. Oh, but the handle 59 00:03:56,080 --> 00:03:58,920 Speaker 1: has been replaced twelve times and the axe head has 60 00:03:58,960 --> 00:04:02,440 Speaker 1: been replaced for teen times. It was obviously a joke, 61 00:04:02,480 --> 00:04:05,320 Speaker 1: but it got me thinking from a young age about 62 00:04:05,320 --> 00:04:09,360 Speaker 1: the nature of identity in the face of change. Does 63 00:04:09,400 --> 00:04:13,480 Speaker 1: something retain its identity if all the parts change? Now, 64 00:04:13,800 --> 00:04:17,359 Speaker 1: why would a neuroscience podcast care about the Ship of 65 00:04:17,440 --> 00:04:22,120 Speaker 1: Theseus or George Washington's acts. It's because that kind of 66 00:04:22,160 --> 00:04:26,560 Speaker 1: wholesale replacement is precisely what's happening to your brain and 67 00:04:26,560 --> 00:04:30,359 Speaker 1: your entire body. A big part of the mystery of 68 00:04:30,440 --> 00:04:33,560 Speaker 1: selfhood has to do with the fact that all the 69 00:04:33,640 --> 00:04:38,839 Speaker 1: pieces and parts that make up you are constantly turning over. 70 00:04:39,680 --> 00:04:43,520 Speaker 1: Your body is built out of thirty trillion cells, and 71 00:04:43,560 --> 00:04:47,520 Speaker 1: this is just cellular stuff. Every bit of the cells 72 00:04:47,920 --> 00:04:51,680 Speaker 1: has a lifetime. Most of the cells die or subdivide 73 00:04:51,720 --> 00:04:54,760 Speaker 1: at some point. But even those cells that stick around 74 00:04:54,839 --> 00:04:58,200 Speaker 1: your whole life and don't divide, like your neurons, they're 75 00:04:58,240 --> 00:05:02,599 Speaker 1: totally different every few years. Why because brain cells aren't 76 00:05:02,640 --> 00:05:06,400 Speaker 1: made out of something stable like metal or cement. Instead, 77 00:05:06,400 --> 00:05:09,599 Speaker 1: they're made out of the basic proteins and lipids and 78 00:05:09,640 --> 00:05:12,520 Speaker 1: other molecules that make up any cell in the body, 79 00:05:12,880 --> 00:05:17,680 Speaker 1: and those things aren't particularly stable. So every single neuron 80 00:05:17,760 --> 00:05:20,640 Speaker 1: and every cell in your body is like the Ship 81 00:05:20,720 --> 00:05:24,400 Speaker 1: of Theseus. Every part of it is getting rebuilt all 82 00:05:24,440 --> 00:05:27,200 Speaker 1: the time. One planket a time, or in this case, 83 00:05:27,240 --> 00:05:31,440 Speaker 1: one molecule at a time. The pieces and parts of 84 00:05:31,480 --> 00:05:35,160 Speaker 1: the cell have no meaningful stability, and so a big 85 00:05:35,200 --> 00:05:39,600 Speaker 1: part of all that cellular machinery is simply building and 86 00:05:39,680 --> 00:05:44,400 Speaker 1: rebuilding and rebuilding, and in this way everything gets replaced. 87 00:05:45,000 --> 00:05:48,880 Speaker 1: So who you are physically changes all the time, and 88 00:05:48,920 --> 00:05:54,080 Speaker 1: the question is how does your self stay intact over 89 00:05:54,120 --> 00:05:59,000 Speaker 1: this changing substrate. The answer is it's not clear that 90 00:05:59,160 --> 00:06:04,960 Speaker 1: it does. But cognitively you have this illusion of stability. 91 00:06:05,360 --> 00:06:08,680 Speaker 1: You are one being. You've spent your whole life with 92 00:06:08,760 --> 00:06:12,400 Speaker 1: a fixed history, as in, I grew up here, here's 93 00:06:12,440 --> 00:06:15,799 Speaker 1: my name, this was my hometown, these are my parents. 94 00:06:16,160 --> 00:06:19,440 Speaker 1: This is how my trajectory in life has unfolded, leading 95 00:06:19,480 --> 00:06:21,159 Speaker 1: me from here to there to there. And so we 96 00:06:21,240 --> 00:06:24,679 Speaker 1: tend to hold the impression that our identities are something 97 00:06:24,760 --> 00:06:30,040 Speaker 1: very stable, but in fact who you are drifts in 98 00:06:30,040 --> 00:06:32,280 Speaker 1: this light. It's always struck me as funny to think 99 00:06:32,279 --> 00:06:35,800 Speaker 1: about the notion of an afterlife, because what age would 100 00:06:35,880 --> 00:06:38,800 Speaker 1: you be. Depending on when you get there, you might 101 00:06:38,839 --> 00:06:41,839 Speaker 1: be a very different person than you were even five 102 00:06:41,880 --> 00:06:44,599 Speaker 1: years before that. And so all this inspired me to 103 00:06:44,720 --> 00:06:47,800 Speaker 1: write a short story that's published in my book Some 104 00:06:48,360 --> 00:06:51,719 Speaker 1: sum and I'm going to read that story to illustrate 105 00:06:51,920 --> 00:06:56,200 Speaker 1: the questions of this episode. The story is called Prism. 106 00:06:56,320 --> 00:06:59,440 Speaker 1: God resolved at the outset that he wanted every human 107 00:06:59,480 --> 00:07:03,360 Speaker 1: to particip paid in the afterlife, but the plans weren't 108 00:07:03,520 --> 00:07:07,120 Speaker 1: thought out to completion, and immediately he began to run 109 00:07:07,240 --> 00:07:11,920 Speaker 1: up against some confusion about age. How old should each 110 00:07:11,960 --> 00:07:16,120 Speaker 1: person be in the afterlife. Should this grandmother exist here 111 00:07:16,160 --> 00:07:19,520 Speaker 1: at her age of death, or should she be allowed 112 00:07:19,560 --> 00:07:23,080 Speaker 1: to live as a young woman recognizable to her first 113 00:07:23,120 --> 00:07:26,760 Speaker 1: lover but not to her granddaughter. He decided it was 114 00:07:26,960 --> 00:07:30,000 Speaker 1: unfair to keep people the age they were at the 115 00:07:30,160 --> 00:07:33,080 Speaker 1: end of their lives, when much of their beauty and 116 00:07:33,120 --> 00:07:37,000 Speaker 1: alacrity had been worn down. Allowing everyone to live as 117 00:07:37,040 --> 00:07:41,880 Speaker 1: a young adult proved an unviable solution, because the afterlife 118 00:07:41,960 --> 00:07:46,920 Speaker 1: quickly degenerated into unbounded sexual pursuits, and at middle ages 119 00:07:47,280 --> 00:07:50,920 Speaker 1: they talked only about their children and mortgages, making conversations 120 00:07:50,920 --> 00:07:55,720 Speaker 1: in the afterlife. Tedious God finally landed on an ingenious 121 00:07:55,720 --> 00:08:00,440 Speaker 1: solution while watching light diffract through a prism. So when 122 00:08:00,440 --> 00:08:04,120 Speaker 1: you arrive here, you are split into your multiple selves 123 00:08:04,280 --> 00:08:08,600 Speaker 1: at all possible ages. The you that existed as a 124 00:08:08,640 --> 00:08:14,120 Speaker 1: single identity is now all ages at once. These pieces 125 00:08:14,160 --> 00:08:18,600 Speaker 1: of you no longer get old, but remain ageless into perpetuity. 126 00:08:19,080 --> 00:08:23,520 Speaker 1: The ewes have transcended time. This takes them getting used 127 00:08:23,560 --> 00:08:26,840 Speaker 1: to The different beams of you might run into each 128 00:08:26,880 --> 00:08:29,520 Speaker 1: other at the grocery store, like separate people do in 129 00:08:29,560 --> 00:08:33,800 Speaker 1: earth life. Your seventy six year old self may revisit 130 00:08:33,840 --> 00:08:37,320 Speaker 1: his favorite creek and run into your eleven year old self. 131 00:08:37,880 --> 00:08:40,040 Speaker 1: Your twenty eight year old self may break up with 132 00:08:40,080 --> 00:08:42,839 Speaker 1: a lover and a diner and notice your thirty five 133 00:08:42,920 --> 00:08:46,920 Speaker 1: year old self visiting that spot, lingering on the air 134 00:08:47,000 --> 00:08:51,560 Speaker 1: of regret hanging over the empty seat. Typically, the different 135 00:08:51,600 --> 00:08:54,680 Speaker 1: youws are happy to see each other because they possess 136 00:08:54,760 --> 00:08:58,040 Speaker 1: the same name in a shared history. But the ewes 137 00:08:58,200 --> 00:09:01,000 Speaker 1: are more critical of yourselves than they are of others, 138 00:09:01,440 --> 00:09:05,640 Speaker 1: and so each you quickly identifies habits that get under 139 00:09:05,720 --> 00:09:09,360 Speaker 1: your skin. It's a fact of the afterlife. Don't be 140 00:09:09,440 --> 00:09:14,280 Speaker 1: surprised to discover that after decomposition into your different ages, 141 00:09:14,880 --> 00:09:19,720 Speaker 1: the different us tend to drift apart. You discover that 142 00:09:19,760 --> 00:09:23,120 Speaker 1: the you of eight years old has less than common 143 00:09:23,160 --> 00:09:25,960 Speaker 1: than expected with the U of thirty two and the 144 00:09:26,080 --> 00:09:29,760 Speaker 1: U of sixty four, The eighteen year old you finds 145 00:09:29,840 --> 00:09:32,760 Speaker 1: more in common with other eighteen year olds than with 146 00:09:32,880 --> 00:09:36,160 Speaker 1: your seventy three year old you. The seventy three year 147 00:09:36,160 --> 00:09:39,960 Speaker 1: old you doesn't mind a bit seeking out meaningful conversations 148 00:09:40,200 --> 00:09:44,760 Speaker 1: with others of the same generation. Beyond the name, the 149 00:09:44,960 --> 00:09:48,880 Speaker 1: us have little else in common, but don't lose hope. 150 00:09:49,320 --> 00:09:54,400 Speaker 1: The shared resume of life, parents, birthplace, hometown, school, years, 151 00:09:54,480 --> 00:09:58,880 Speaker 1: first kiss has a magnetic nostalgic pull. So once in 152 00:09:58,880 --> 00:10:02,800 Speaker 1: a while, the different yous organize a gathering like a 153 00:10:02,800 --> 00:10:07,800 Speaker 1: family reunion, bringing together all your ages into a single room. 154 00:10:08,080 --> 00:10:11,520 Speaker 1: At these reunions, the middle aged will delightedly pinch the 155 00:10:11,600 --> 00:10:15,160 Speaker 1: cheeks of the young, and the teenagers will politely listen 156 00:10:15,200 --> 00:10:18,959 Speaker 1: to the stories and advice of the elderly. These reunions 157 00:10:19,280 --> 00:10:23,920 Speaker 1: reveal a group of individuals touchingly searching for a common theme. 158 00:10:24,600 --> 00:10:27,960 Speaker 1: They appeal to your name as a unifying structure, but 159 00:10:28,040 --> 00:10:31,440 Speaker 1: they come to realize that the name that existed on earth, 160 00:10:31,960 --> 00:10:36,360 Speaker 1: the you that moved serially through these different identities, was 161 00:10:36,440 --> 00:10:40,360 Speaker 1: like a bundle of sticks from different trees. They come 162 00:10:40,400 --> 00:10:45,800 Speaker 1: to understand with awe the complexity of the compound identity 163 00:10:45,880 --> 00:10:49,360 Speaker 1: that existed on the earth. They conclude with a shudder, 164 00:10:49,840 --> 00:10:55,520 Speaker 1: that the earthly you is utterly lost, unpreserved in the afterlife. 165 00:10:55,559 --> 00:11:00,640 Speaker 1: You were all these ages, they concede, and you were none. 166 00:11:15,240 --> 00:11:18,000 Speaker 1: So we're changing all the time. But why is it 167 00:11:18,440 --> 00:11:21,960 Speaker 1: hard to keep track of these changes? Obviously it's because 168 00:11:22,280 --> 00:11:26,439 Speaker 1: everything in our lives and our biology changes so slowly. 169 00:11:26,960 --> 00:11:30,120 Speaker 1: It's like the hour hand of a clock. You can 170 00:11:30,160 --> 00:11:32,720 Speaker 1: see that it's moved, but you can't see it move. 171 00:11:33,440 --> 00:11:36,400 Speaker 1: In general, we can see change most readily in the 172 00:11:36,440 --> 00:11:39,800 Speaker 1: growth of our children. You look back at photographs from 173 00:11:39,840 --> 00:11:42,200 Speaker 1: a year ago on your phone and you can't believe 174 00:11:42,240 --> 00:11:44,840 Speaker 1: how much things have changed. But it's hard to keep 175 00:11:44,840 --> 00:11:48,760 Speaker 1: track of the changes in yourself. A friend of my 176 00:11:48,880 --> 00:11:52,079 Speaker 1: parents went to his high school reunion, which was taking 177 00:11:52,080 --> 00:11:54,400 Speaker 1: place at a hotel, and he went around looking at 178 00:11:54,400 --> 00:11:57,440 Speaker 1: the different conference rooms to figure out which one was 179 00:11:57,440 --> 00:12:00,120 Speaker 1: the correct class because they were divided up by decades, 180 00:12:00,559 --> 00:12:02,240 Speaker 1: And he thought he found the right room, but he 181 00:12:02,320 --> 00:12:05,600 Speaker 1: popped his head in and he realized that's completely not 182 00:12:05,679 --> 00:12:07,840 Speaker 1: the right room. All of those are very old people. 183 00:12:08,200 --> 00:12:10,320 Speaker 1: And then he stepped back and looked at the sign 184 00:12:10,760 --> 00:12:13,880 Speaker 1: and realized that indeed this was the correct room, and 185 00:12:14,000 --> 00:12:17,839 Speaker 1: he too must presumably look that old to others, even 186 00:12:17,880 --> 00:12:21,079 Speaker 1: if he still thought of himself as young on the inside. 187 00:12:21,800 --> 00:12:24,080 Speaker 1: So it's hard to keep track of our own changes 188 00:12:24,120 --> 00:12:29,640 Speaker 1: because they happen slowly. But maybe the thing that binds 189 00:12:29,679 --> 00:12:34,760 Speaker 1: your self together across the ever changing physical substrate is 190 00:12:34,800 --> 00:12:38,520 Speaker 1: the one thing you have that remains constant, your memory. 191 00:12:39,200 --> 00:12:43,040 Speaker 1: Memory ties all these versions of you together. Memory serves 192 00:12:43,080 --> 00:12:47,559 Speaker 1: as the thread that weaves through all these transformations, anchoring 193 00:12:48,080 --> 00:12:50,600 Speaker 1: a sense of self. So that sounds very nice, but 194 00:12:50,640 --> 00:12:53,840 Speaker 1: there's a fundamental problem with this, which is that memory 195 00:12:53,960 --> 00:12:58,439 Speaker 1: itself is not stable. It drifts, and I've talked about 196 00:12:58,440 --> 00:13:03,720 Speaker 1: this in several episodes. Memory is not a faithful, unchanging 197 00:13:03,800 --> 00:13:07,880 Speaker 1: record of the past. It's instead a fragile brain state, 198 00:13:07,960 --> 00:13:11,760 Speaker 1: and it needs to be reactivated and reconstructed each time 199 00:13:11,880 --> 00:13:17,080 Speaker 1: you recall it. And in this process, memories morph, So 200 00:13:17,120 --> 00:13:19,560 Speaker 1: we can't really think of them as an archive. They're 201 00:13:19,600 --> 00:13:24,520 Speaker 1: more of a story which we continually rewrite. And that 202 00:13:24,559 --> 00:13:27,280 Speaker 1: would be fine to keep rewriting a story, except that 203 00:13:27,320 --> 00:13:30,400 Speaker 1: we assume at all times that our memories form the 204 00:13:30,600 --> 00:13:34,120 Speaker 1: core of a stable identity. So let me give an 205 00:13:34,160 --> 00:13:37,680 Speaker 1: example of how memories change. Imagine that you and two 206 00:13:37,760 --> 00:13:41,000 Speaker 1: friends were at some rooftop party and you were best 207 00:13:41,000 --> 00:13:43,760 Speaker 1: friends since college, and the night was full of jokes 208 00:13:43,760 --> 00:13:47,280 Speaker 1: and old stories, and you remember feeling grateful for this 209 00:13:47,440 --> 00:13:49,960 Speaker 1: bond that you shared, and you can still picture the 210 00:13:50,000 --> 00:13:53,319 Speaker 1: three of you by the fireplace, vowing to never let 211 00:13:53,360 --> 00:13:57,400 Speaker 1: life pull you apart. But now, a year later, everything 212 00:13:57,440 --> 00:14:00,760 Speaker 1: has changed. Those two guys are now enemies. It all 213 00:14:00,800 --> 00:14:02,880 Speaker 1: fell apart because one of them had an affair with 214 00:14:02,920 --> 00:14:05,880 Speaker 1: the other's girlfriend. So now when you think back on 215 00:14:05,920 --> 00:14:09,360 Speaker 1: that rooftop party, you wonder was there something in the 216 00:14:09,360 --> 00:14:13,880 Speaker 1: way he and the other guy's girlfriend exchanged glances across 217 00:14:13,920 --> 00:14:17,160 Speaker 1: the room? You now think you sort of remember there 218 00:14:17,240 --> 00:14:20,920 Speaker 1: were little stolen looks, there was some subtle tension in 219 00:14:20,960 --> 00:14:24,200 Speaker 1: the air. Did your other friends sense that something was funny? 220 00:14:24,360 --> 00:14:28,000 Speaker 1: Even then, the memory that once felt warm and comforting 221 00:14:28,000 --> 00:14:31,040 Speaker 1: now feels different, like a scene in a movie that 222 00:14:31,080 --> 00:14:34,480 Speaker 1: you're watching for the second time but noticing new things. Now. 223 00:14:34,600 --> 00:14:38,000 Speaker 1: The past hasn't changed, but your present knowledge of what 224 00:14:38,160 --> 00:14:42,600 Speaker 1: came after that party colors the memory and reshapes it, 225 00:14:42,640 --> 00:14:44,560 Speaker 1: and it makes you question what was really there and 226 00:14:44,600 --> 00:14:49,720 Speaker 1: what you've unconsciously added. Memory is slippery like that, the 227 00:14:49,720 --> 00:14:53,440 Speaker 1: more you revisit it, the more it shifts and blurs, 228 00:14:53,920 --> 00:14:56,920 Speaker 1: which reminds me of a great quotation from Sigmund Freud 229 00:14:57,000 --> 00:14:59,800 Speaker 1: on this topic. In eighteen ninety six, he wrote letter 230 00:14:59,840 --> 00:15:03,760 Speaker 1: to a colleague about quote, the material present in the 231 00:15:03,800 --> 00:15:08,600 Speaker 1: form of memory traces being subjected from time to time 232 00:15:08,680 --> 00:15:15,360 Speaker 1: to a rearrangement in accordance with fresh circumstances, to a retranscription. 233 00:15:15,920 --> 00:15:18,480 Speaker 1: And there's another quotation that I cite often from a 234 00:15:18,520 --> 00:15:22,600 Speaker 1: writer named John Dufresny, who once wrote that quote, Memory 235 00:15:22,800 --> 00:15:26,200 Speaker 1: is a myth making machine. What we do is keep 236 00:15:26,520 --> 00:15:30,480 Speaker 1: revising our past to keep it consistent with who we 237 00:15:30,640 --> 00:15:33,680 Speaker 1: think we are. So here's where we are so far. 238 00:15:34,160 --> 00:15:36,920 Speaker 1: Our biology is always changing, and so the thing that 239 00:15:37,040 --> 00:15:40,360 Speaker 1: crosses time is our memory. But even that changes all 240 00:15:40,400 --> 00:15:44,320 Speaker 1: the time, drifting or warping or disintegrating altogether. And as 241 00:15:44,400 --> 00:15:48,920 Speaker 1: a result, who you are is always on the move. Now, 242 00:15:48,960 --> 00:15:52,320 Speaker 1: I've been speaking as though we're not always aware of 243 00:15:52,400 --> 00:15:54,760 Speaker 1: so much change happening over time, But of course we 244 00:15:54,840 --> 00:15:57,280 Speaker 1: can come to be aware of this in some circumstances. 245 00:15:57,600 --> 00:16:00,440 Speaker 1: For example, when you look back at a diary entry 246 00:16:00,480 --> 00:16:03,880 Speaker 1: that you wrote some years ago, it's often surprising how 247 00:16:03,960 --> 00:16:07,080 Speaker 1: much you've changed, how much the person who held that 248 00:16:07,280 --> 00:16:10,400 Speaker 1: pen is a bit different than who you are now. 249 00:16:10,760 --> 00:16:14,520 Speaker 1: So we do confront this sometimes. But what's weird is 250 00:16:14,600 --> 00:16:18,600 Speaker 1: despite the massive changes that happen in our past, we 251 00:16:18,760 --> 00:16:22,320 Speaker 1: always think that there will be little change in the future. 252 00:16:23,040 --> 00:16:26,000 Speaker 1: We've changed a lot up until now, but now we've 253 00:16:26,040 --> 00:16:29,560 Speaker 1: settled into place and there won't be much change from here. 254 00:16:30,000 --> 00:16:33,240 Speaker 1: And this is a cognitive illusion known as the end 255 00:16:33,280 --> 00:16:37,800 Speaker 1: of history illusion. In other words, we can recognize significant 256 00:16:37,880 --> 00:16:40,000 Speaker 1: changes in ourselves when we think about our past, but 257 00:16:40,080 --> 00:16:43,720 Speaker 1: we underestimate how much we're going to change in the future. 258 00:16:44,120 --> 00:16:48,440 Speaker 1: We acknowledge that we've grown or evolved, but we incorrectly 259 00:16:48,480 --> 00:16:51,800 Speaker 1: assume that who we are right now is pretty close 260 00:16:51,840 --> 00:16:56,640 Speaker 1: to our final or mature version of ourselves. This end 261 00:16:56,680 --> 00:17:00,440 Speaker 1: of history illusion was first studied by psychology just like 262 00:17:00,560 --> 00:17:03,640 Speaker 1: Daniel Gilbert and his colleagues, and they surveyed people on 263 00:17:03,760 --> 00:17:07,600 Speaker 1: their values and their preferences, their personality traits, their life goals, 264 00:17:07,880 --> 00:17:11,960 Speaker 1: and across the board. They found that people consistently believe 265 00:17:12,520 --> 00:17:15,120 Speaker 1: that they've undergone more change in the past than they 266 00:17:15,119 --> 00:17:18,560 Speaker 1: will in the future. But of course it's an illusion 267 00:17:18,800 --> 00:17:23,200 Speaker 1: because change is a continuous process. In other words, if 268 00:17:23,240 --> 00:17:27,120 Speaker 1: I ask you now if you've essentially finished changing in life, 269 00:17:27,160 --> 00:17:29,960 Speaker 1: if you're likes and personality have settled, you'll say yeah. 270 00:17:30,119 --> 00:17:32,760 Speaker 1: But if I track you down and ask you again 271 00:17:32,800 --> 00:17:36,720 Speaker 1: in five years, you'll say, actually, the past five years 272 00:17:37,000 --> 00:17:39,840 Speaker 1: did hold a lot of change for me, but now 273 00:17:40,119 --> 00:17:42,720 Speaker 1: I've finally arrived at my stable self. And it's the 274 00:17:42,760 --> 00:17:45,399 Speaker 1: same story if I survey you five years after that. 275 00:17:45,720 --> 00:17:48,800 Speaker 1: And this is problematic because, for example, we're always trying 276 00:17:48,840 --> 00:17:53,080 Speaker 1: to predict our future emotions. You think, oh, if I 277 00:17:53,119 --> 00:17:56,520 Speaker 1: get that job promotion, or if I'm in this relationship, 278 00:17:56,640 --> 00:17:59,080 Speaker 1: or if I have kids, or if I don't have kids, 279 00:17:59,320 --> 00:18:01,480 Speaker 1: this will make me real happy. Or if I lose 280 00:18:01,560 --> 00:18:03,200 Speaker 1: this job and I have to find a new one, 281 00:18:03,200 --> 00:18:05,840 Speaker 1: that's going to make me miserable. This is what psychologists 282 00:18:05,840 --> 00:18:10,040 Speaker 1: call affective forecasting, where we project how we think we're 283 00:18:10,080 --> 00:18:13,720 Speaker 1: going to feel, but it's based on your current limited 284 00:18:13,760 --> 00:18:17,000 Speaker 1: knowledge about the world, and that might change. So why 285 00:18:17,000 --> 00:18:19,760 Speaker 1: do we have an end of history illusion. Well, presumably 286 00:18:20,119 --> 00:18:22,560 Speaker 1: it's because it's easier for us to see the past 287 00:18:22,640 --> 00:18:26,359 Speaker 1: changes because we have memories and experiences to draw from, 288 00:18:26,880 --> 00:18:31,520 Speaker 1: but future changes are hidden in the midst of the future. 289 00:18:31,560 --> 00:18:33,880 Speaker 1: We don't know what they are, so let me give 290 00:18:33,880 --> 00:18:37,280 Speaker 1: you some concrete examples of this. Think about the way 291 00:18:37,680 --> 00:18:40,920 Speaker 1: we have our career goals. As a thirty year old, 292 00:18:40,960 --> 00:18:44,840 Speaker 1: you might look back and realize your career aspirations have changed, 293 00:18:44,880 --> 00:18:48,159 Speaker 1: maybe significantly, from the time you were twenty, but you 294 00:18:48,200 --> 00:18:51,600 Speaker 1: might assume that your current career goals are unlikely to 295 00:18:51,720 --> 00:18:53,880 Speaker 1: change much in the next ten years, even though lots 296 00:18:53,920 --> 00:18:57,400 Speaker 1: of people shift career paths or professional interests throughout life. 297 00:18:57,600 --> 00:19:01,280 Speaker 1: Or think about your music preferences. Are older, you may 298 00:19:01,320 --> 00:19:04,800 Speaker 1: recognize that your taste in music has evolved since your 299 00:19:04,840 --> 00:19:08,560 Speaker 1: teenage years. Maybe you went from poper rock to maybe 300 00:19:08,760 --> 00:19:12,320 Speaker 1: jazz or classical. But despite that, you're likely to believe 301 00:19:12,359 --> 00:19:15,440 Speaker 1: that your current musical preferences are going to remain stable 302 00:19:15,760 --> 00:19:17,760 Speaker 1: for the rest of your life, even though your musical 303 00:19:17,800 --> 00:19:21,360 Speaker 1: tastes are going to keep evolving with exposure to new 304 00:19:21,480 --> 00:19:25,160 Speaker 1: genres and bands and instruments that don't even exist yet. 305 00:19:25,680 --> 00:19:29,640 Speaker 1: We're thinking about friendships. In your early twenties, you might 306 00:19:29,640 --> 00:19:32,800 Speaker 1: reflect on how your circle of friends has changed from 307 00:19:33,000 --> 00:19:36,200 Speaker 1: high school to college. There's a big shift in relationships there, 308 00:19:36,400 --> 00:19:39,600 Speaker 1: but you might simultaneously feel certain that the college friends 309 00:19:39,600 --> 00:19:42,720 Speaker 1: you have now are going to be your closest companions 310 00:19:42,720 --> 00:19:47,320 Speaker 1: for life. That's a totally understandable position, but it underestimates 311 00:19:47,680 --> 00:19:51,720 Speaker 1: how friendships shift as you enter different life stages, like 312 00:19:51,960 --> 00:19:53,800 Speaker 1: when you start a family or you move to a 313 00:19:53,840 --> 00:19:57,440 Speaker 1: new city. The same reasoning applies to everything. So take 314 00:19:57,520 --> 00:20:00,960 Speaker 1: hobbies and interest When you're in your fifth these you 315 00:20:01,040 --> 00:20:03,439 Speaker 1: notice that you've taken up new hobbies and given up 316 00:20:03,520 --> 00:20:06,560 Speaker 1: old ones over the years, but you'll generally believe that 317 00:20:06,600 --> 00:20:09,680 Speaker 1: your current interests will remain consistent for the coming decades, 318 00:20:09,720 --> 00:20:13,360 Speaker 1: when in fact, new hobbies and interests will still emerge. 319 00:20:13,600 --> 00:20:17,000 Speaker 1: You just can't see that because they're ensconced in the 320 00:20:17,080 --> 00:20:22,120 Speaker 1: dark forest of the future. Possibly there's some new technology 321 00:20:22,160 --> 00:20:24,440 Speaker 1: that you're going to be obsessed with that hasn't even 322 00:20:24,480 --> 00:20:27,320 Speaker 1: been invented or named yet. Okay, And the one that's 323 00:20:27,440 --> 00:20:31,800 Speaker 1: really hard for us to admit to is future changes 324 00:20:32,119 --> 00:20:37,120 Speaker 1: in our political values and social beliefs, and possibly religious beliefs. 325 00:20:37,760 --> 00:20:39,800 Speaker 1: When you look back on any of your beliefs from 326 00:20:39,920 --> 00:20:42,520 Speaker 1: a decade ago, you can sometimes see there have been 327 00:20:42,560 --> 00:20:45,199 Speaker 1: some changes. But again, we tend to assume that our 328 00:20:45,240 --> 00:20:47,680 Speaker 1: current values are now locked into place for the rest 329 00:20:47,720 --> 00:20:51,399 Speaker 1: of our lives. We all fail to anticipate that our 330 00:20:51,440 --> 00:20:56,840 Speaker 1: worldview is going to continue to get reshaped by life experiences, 331 00:20:56,920 --> 00:21:02,080 Speaker 1: by new information, by changing social contexts. In a decade, 332 00:21:02,560 --> 00:21:22,240 Speaker 1: we might not be precisely who we are right now. Now, 333 00:21:22,280 --> 00:21:26,119 Speaker 1: this whole end of history illusion wouldn't really matter for 334 00:21:26,240 --> 00:21:29,400 Speaker 1: our lives, except that it affects how we make decisions. 335 00:21:29,720 --> 00:21:33,080 Speaker 1: Because so much of what you do is in service 336 00:21:33,400 --> 00:21:38,040 Speaker 1: to the assumed future you. You suffer through courses and 337 00:21:38,119 --> 00:21:42,240 Speaker 1: trainings now to make things better for your future you. 338 00:21:42,240 --> 00:21:46,240 Speaker 1: You sweat through a workout so your future you will 339 00:21:46,240 --> 00:21:49,359 Speaker 1: have a better body. You put your money into retirement 340 00:21:49,440 --> 00:21:52,560 Speaker 1: plans to make sure that the future you has the 341 00:21:52,600 --> 00:21:57,480 Speaker 1: resources that you predict that stranger will need. The difficulty 342 00:21:57,560 --> 00:22:00,440 Speaker 1: simply is that we're not good predictors. You don't really 343 00:22:00,520 --> 00:22:05,320 Speaker 1: know who that person is. That person shares your name 344 00:22:05,400 --> 00:22:07,720 Speaker 1: and your history, but the fact is that person might 345 00:22:07,800 --> 00:22:12,480 Speaker 1: be very different than the current you. So you're donating 346 00:22:12,520 --> 00:22:15,680 Speaker 1: your retirement money for this future person that you can 347 00:22:15,800 --> 00:22:21,560 Speaker 1: essentially guarantee will be not who you currently believe. That 348 00:22:21,600 --> 00:22:24,720 Speaker 1: person might vote for the other political party what you 349 00:22:24,760 --> 00:22:27,679 Speaker 1: would never vote for and yet you're slaving away and 350 00:22:27,760 --> 00:22:31,479 Speaker 1: handing over all your money to that maniac. And you 351 00:22:31,520 --> 00:22:35,320 Speaker 1: also do stuff assuming the best about your future self, 352 00:22:35,400 --> 00:22:38,639 Speaker 1: but sometimes that's not useful either. We tend to assume 353 00:22:38,640 --> 00:22:42,440 Speaker 1: that our future self will be more motivated or disciplined 354 00:22:42,760 --> 00:22:45,520 Speaker 1: than we are today. So because of that, you might 355 00:22:45,640 --> 00:22:50,360 Speaker 1: sign up for an expensive gym membership believing that you'll 356 00:22:50,400 --> 00:22:53,160 Speaker 1: be more committed in the future, but then you don't 357 00:22:53,200 --> 00:22:56,840 Speaker 1: really follow through. Your future self isn't as on board 358 00:22:56,880 --> 00:23:01,120 Speaker 1: with the plan as your past self believed it. As 359 00:23:01,119 --> 00:23:05,080 Speaker 1: a related example, I'm chronically over committed because at every 360 00:23:05,119 --> 00:23:08,439 Speaker 1: moment I assume that my future self is going to 361 00:23:08,480 --> 00:23:11,040 Speaker 1: be less busy than I am now, and so I 362 00:23:11,160 --> 00:23:15,320 Speaker 1: say yes to future invitations or obligations like taking on 363 00:23:15,640 --> 00:23:19,320 Speaker 1: big new projects or attending multiple social events, And when 364 00:23:19,320 --> 00:23:23,639 Speaker 1: the time arrives, my future me wishes that my past 365 00:23:23,760 --> 00:23:27,719 Speaker 1: me hadn't over committed. And more generally, we fall victim 366 00:23:27,960 --> 00:23:32,720 Speaker 1: to lots of planning fallacies. We underestimate how long it's 367 00:23:32,720 --> 00:23:36,480 Speaker 1: going to take to complete some task. You might think cool, 368 00:23:36,520 --> 00:23:38,280 Speaker 1: I can knock that thing out in a week, and 369 00:23:38,320 --> 00:23:40,679 Speaker 1: then you find that it takes twice as long. Now. 370 00:23:40,760 --> 00:23:45,200 Speaker 1: That happens because we typically fail to correctly predict all 371 00:23:45,320 --> 00:23:49,440 Speaker 1: the possible setbacks and complexities that will run into in 372 00:23:49,480 --> 00:23:53,439 Speaker 1: the future. My favorite example of a planning fallacy is 373 00:23:53,480 --> 00:23:57,520 Speaker 1: with a gentleman named James Murray who in eighteen seventy 374 00:23:57,560 --> 00:24:01,560 Speaker 1: eight set out to write the English Dictionary. And the 375 00:24:01,640 --> 00:24:04,879 Speaker 1: idea was to capture all the words in the English 376 00:24:04,920 --> 00:24:08,880 Speaker 1: speaking world and give definitions for all of their various 377 00:24:09,000 --> 00:24:12,399 Speaker 1: shades of meaning. And this seemed like a big undertaking, 378 00:24:12,440 --> 00:24:14,679 Speaker 1: but not big enough that he couldn't complete it in 379 00:24:14,720 --> 00:24:18,800 Speaker 1: a few years. So he worked on this for thirty 380 00:24:18,960 --> 00:24:23,160 Speaker 1: six years until he died, and then several editors took 381 00:24:23,240 --> 00:24:26,439 Speaker 1: up the mantle after him, and the first edition of 382 00:24:26,560 --> 00:24:32,560 Speaker 1: the Oxford English Dictionary was finally completed seventy years after 383 00:24:32,600 --> 00:24:37,399 Speaker 1: he began. He totally misapprehended the size of the project, 384 00:24:37,800 --> 00:24:40,280 Speaker 1: and if I were here, I presumably would have done 385 00:24:40,640 --> 00:24:43,399 Speaker 1: the same. So as a result of this sort of 386 00:24:43,840 --> 00:24:49,600 Speaker 1: planning fallacy, we're constantly making decisions that our future selves 387 00:24:49,840 --> 00:24:53,119 Speaker 1: are going to regret or disagree with. Why. It's not 388 00:24:53,160 --> 00:24:57,679 Speaker 1: because we're idiots now, but instead because our circumstances and 389 00:24:57,720 --> 00:25:02,200 Speaker 1: our preferences and our priorities are go to change over time. Okay, 390 00:25:02,440 --> 00:25:04,439 Speaker 1: so let me zoom back out to the big picture. 391 00:25:04,480 --> 00:25:08,800 Speaker 1: We are creatures who live and change through time, but 392 00:25:08,880 --> 00:25:12,480 Speaker 1: we're yoked with this illusion that we are unchanging, and 393 00:25:12,560 --> 00:25:16,119 Speaker 1: so we misremember our past and we work hard for 394 00:25:16,240 --> 00:25:19,840 Speaker 1: future versions of ourselves who we assume will be like us, 395 00:25:20,119 --> 00:25:22,800 Speaker 1: but they may not be. And by the way, there 396 00:25:22,800 --> 00:25:26,240 Speaker 1: are all kinds of complex relationships between your future self 397 00:25:26,280 --> 00:25:29,160 Speaker 1: and your past self through time, so it gets pretty crowded. 398 00:25:29,480 --> 00:25:32,240 Speaker 1: Your past self says, oh, I'm not gonna worry about 399 00:25:32,280 --> 00:25:35,159 Speaker 1: my future self, and your future self looks back and says, 400 00:25:35,400 --> 00:25:38,199 Speaker 1: what a jerk like When people make the decision in 401 00:25:38,280 --> 00:25:42,600 Speaker 1: the short term to postpone their education or splurge on 402 00:25:42,640 --> 00:25:46,320 Speaker 1: some overpriced thing, and then your future self thinks, dang, 403 00:25:46,359 --> 00:25:49,199 Speaker 1: I wish I'd gone to that class or spent my 404 00:25:49,359 --> 00:25:53,800 Speaker 1: money on something more meaningful or necessary. This comes up 405 00:25:53,800 --> 00:25:56,800 Speaker 1: for many people. In terms of retirement savings. People will 406 00:25:56,800 --> 00:25:59,320 Speaker 1: make the decision to spend now rather than save for 407 00:25:59,359 --> 00:26:03,240 Speaker 1: their future self. They keep thinking, oh, I'll start saving later, 408 00:26:03,720 --> 00:26:07,520 Speaker 1: But then as retirement approaches, your future self feels mad 409 00:26:07,520 --> 00:26:10,280 Speaker 1: at your past self and wishes you had started saving earlier, 410 00:26:10,960 --> 00:26:13,760 Speaker 1: and I suspect this is true. Anytime we choose instant 411 00:26:13,760 --> 00:26:17,440 Speaker 1: gratification over long term goals, our future selves look back 412 00:26:17,480 --> 00:26:19,959 Speaker 1: and they're mad about it. And all this highlights the 413 00:26:20,119 --> 00:26:25,520 Speaker 1: challenge of balancing short term desires with long term outcomes. 414 00:26:25,800 --> 00:26:28,719 Speaker 1: In other words, your self in the moment now versus 415 00:26:28,760 --> 00:26:32,560 Speaker 1: yourself in the future. So let's wrap up. In the 416 00:26:32,600 --> 00:26:35,760 Speaker 1: next episode, Part two, we're going to dive deeper into 417 00:26:35,760 --> 00:26:38,439 Speaker 1: all these paradoxes of the self by talking with my 418 00:26:38,520 --> 00:26:42,520 Speaker 1: colleague neuroscientist Mike Levin, who wrote a recent paper in 419 00:26:42,520 --> 00:26:46,760 Speaker 1: which he pointed out that quote if we do not change, 420 00:26:47,000 --> 00:26:51,800 Speaker 1: learning and growth is impossible. If we do change, does 421 00:26:51,840 --> 00:26:55,800 Speaker 1: not the current self cease to exist in an important 422 00:26:55,840 --> 00:26:59,359 Speaker 1: sense end quote. So let's summarize where we got in 423 00:26:59,440 --> 00:27:03,560 Speaker 1: this episode. We began by looking at the illusion of continuity, 424 00:27:03,640 --> 00:27:06,560 Speaker 1: and we use the ancient thought experiment of the ship 425 00:27:06,640 --> 00:27:09,560 Speaker 1: of Theseus, where one plank of the ship gets replaced 426 00:27:09,560 --> 00:27:12,000 Speaker 1: at a time, and we can ask is it still 427 00:27:12,080 --> 00:27:15,520 Speaker 1: the ship of Theseus after every plank has been replaced. 428 00:27:16,040 --> 00:27:19,360 Speaker 1: We looked at this question because we are always surfing 429 00:27:19,480 --> 00:27:23,880 Speaker 1: on top of constant physical changes, and yet we perceive 430 00:27:23,960 --> 00:27:28,800 Speaker 1: ourselves as consistent over time. The planks and theseus's ship 431 00:27:29,119 --> 00:27:32,000 Speaker 1: are the cells and molecules in your body, and this 432 00:27:32,160 --> 00:27:36,520 Speaker 1: foregrounds the question about what makes you the same person 433 00:27:36,640 --> 00:27:39,800 Speaker 1: over time. We asked the question of whether we can 434 00:27:39,840 --> 00:27:43,840 Speaker 1: really say that memory is the thread holding identity together, 435 00:27:43,960 --> 00:27:47,720 Speaker 1: because the truth is that memory is far from reliable. 436 00:27:48,119 --> 00:27:52,560 Speaker 1: It's constantly being rewritten. And finally, we touched on a 437 00:27:52,600 --> 00:27:56,000 Speaker 1: cognitive bias known as the end of history illusion, which 438 00:27:56,040 --> 00:27:58,960 Speaker 1: is where we massively underestimate how much we're going to 439 00:27:59,080 --> 00:28:01,240 Speaker 1: change in the future, even though we're aware that we've 440 00:28:01,359 --> 00:28:05,120 Speaker 1: changed in the past. We tend to believe that our 441 00:28:05,240 --> 00:28:08,359 Speaker 1: current tastes and values and personalities are going to remain 442 00:28:08,480 --> 00:28:12,639 Speaker 1: consistent from here on out, even though we keep on 443 00:28:12,840 --> 00:28:17,800 Speaker 1: changing throughout our lives. So you can't actually be your 444 00:28:18,000 --> 00:28:20,720 Speaker 1: past self. But as we'll see in part two next week, 445 00:28:21,119 --> 00:28:25,760 Speaker 1: we constantly try to reconstruct that person. We constantly try 446 00:28:25,800 --> 00:28:30,960 Speaker 1: to revivify that past self based on the evidence provided 447 00:28:31,440 --> 00:28:34,399 Speaker 1: by reinterpreting the clues that are left by them. In 448 00:28:34,440 --> 00:28:38,240 Speaker 1: other words, the memories that are buried in the neural network. 449 00:28:38,880 --> 00:28:42,640 Speaker 1: In this view, memories are like a message in a bottle. 450 00:28:43,040 --> 00:28:47,040 Speaker 1: Thrown from your present self into the ocean for someone 451 00:28:47,120 --> 00:28:52,080 Speaker 1: to find, and that someone is a future you who 452 00:28:52,120 --> 00:28:58,959 Speaker 1: you don't necessarily know. Go to eagleman dot com slash 453 00:28:59,000 --> 00:29:02,960 Speaker 1: podcast for more information and to find further reading. Send 454 00:29:02,960 --> 00:29:05,440 Speaker 1: me an email at podcasts at eagleman dot com with 455 00:29:05,600 --> 00:29:09,360 Speaker 1: questions or discussion and check out Subscribe to Inner Cosmos 456 00:29:09,360 --> 00:29:12,000 Speaker 1: on YouTube for videos of each episode and to leave 457 00:29:12,040 --> 00:29:15,720 Speaker 1: comments until next time. I'm David Eagleman and this is 458 00:29:15,840 --> 00:29:18,760 Speaker 1: Inner at Cosmos.