1 00:00:00,218 --> 00:00:03,850 Life is fundamentally different from dead stuff—or is it? 2 00:00:04,090 --> 00:00:07,567 Physicist Erwin Schrödinger defined life this way: 3 00:00:07,567 --> 00:00:12,314 Living things avoid decay into disorder and equilibrium. 4 00:00:13,074 --> 00:00:14,048 What does this mean? 5 00:00:14,508 --> 00:00:17,361 Let’s pretend that your download folder is the universe. 6 00:00:17,361 --> 00:00:21,058 It started orderly and got more and more chaotic over time. 7 00:00:21,678 --> 00:00:25,466 By investing energy, you can create order and clean it up. 8 00:00:25,926 --> 00:00:27,490 This is what living things do. 9 00:00:27,920 --> 00:00:29,778 But what is life? 10 00:00:36,564 --> 00:00:39,457 Every living thing on this planet is made of cells. 11 00:00:39,617 --> 00:00:45,182 Basically, a cell is a protein-based robot too small to feel or experience anything. 12 00:00:45,492 --> 00:00:48,151 It has the properties we just assign to life: 13 00:00:48,151 --> 00:00:51,674 it has a wall that separates it from the surroundings, creating order; 14 00:00:51,674 --> 00:00:55,934 it regulates itself and maintains a constant state; 15 00:00:55,934 --> 00:00:58,280 it eats stuff to stay alive; 16 00:00:58,280 --> 00:01:00,134 it grows and develops; 17 00:01:00,134 --> 00:01:01,879 it reacts to the environment; 18 00:01:01,879 --> 00:01:04,394 and it’s subject to evolution; 19 00:01:04,394 --> 00:01:06,383 and it makes more of itself. 20 00:01:06,743 --> 00:01:10,590 But of all the stuff that makes up a cell, no part is alive. 21 00:01:10,960 --> 00:01:15,087 Stuff reacts chemically with other stuff, forming reactions 22 00:01:15,087 --> 00:01:17,946 that start other reactions which start other reactions. 23 00:01:18,446 --> 00:01:23,206 In a single cell, every second several million chemical reactions take place, 24 00:01:23,206 --> 00:01:25,094 forming a complex orchestra. 25 00:01:25,584 --> 00:01:28,405 A cell can build several thousand types of protein: 26 00:01:28,405 --> 00:01:31,809 some very simple, some complex micromachines. 27 00:01:32,559 --> 00:01:37,615 Imagine driving a car at 100 km/h while constantly rebuilding every single 28 00:01:37,615 --> 00:01:40,165 part of it with stuff you collect from the street. 29 00:01:40,675 --> 00:01:42,471 That is what cells do. 30 00:01:43,051 --> 00:01:46,747 But no part of the cell is alive; everything is dead matter 31 00:01:46,747 --> 00:01:48,877 moved by the laws of the universe. 32 00:01:49,537 --> 00:01:54,367 So is life the aggregate of all these reaction processes that are taking place? 33 00:01:55,187 --> 00:01:57,636 Eventually, every living thing will die. 34 00:01:58,336 --> 00:02:02,791 The goal of the whole process is to prevent this by producing new entities; 35 00:02:03,191 --> 00:02:05,429 and by this, we mean DNA. 36 00:02:06,049 --> 00:02:10,248 Life is, in a way, just a lot of stuff that carries genetic information around. 37 00:02:10,778 --> 00:02:12,826 Every living thing is subject to evolution, 38 00:02:12,826 --> 00:02:17,461 and the DNA that develops the best living thing around it will stay in the game. 39 00:02:18,071 --> 00:02:20,293 So, is DNA life, then? 40 00:02:20,863 --> 00:02:25,553 If you take DNA out of its hull, it certainly is a very complex molecule, 41 00:02:25,553 --> 00:02:27,745 but it can’t do anything by itself. 42 00:02:28,235 --> 00:02:31,790 This is where viruses make everything more complicated. 43 00:02:32,100 --> 00:02:36,256 They are basically strings of RNA or DNA in a small hull 44 00:02:36,256 --> 00:02:38,573 and need cells to do something. 45 00:02:38,573 --> 00:02:41,305 We’re not sure if they count as living or dead. 46 00:02:41,305 --> 00:02:47,118 And still, there are 225,000,000 m³ of viruses on Earth. 47 00:02:47,118 --> 00:02:49,385 They don’t seem to care what we think of them. 48 00:02:49,385 --> 00:02:53,723 There are even viruses that invade dead cells and reanimate them 49 00:02:53,723 --> 00:02:57,530 so they can be a host for them, which blurs the line even more. 50 00:02:58,310 --> 00:02:59,579 Or mitochondria. 51 00:02:59,949 --> 00:03:03,219 They are the power plants of most complex cells and 52 00:03:03,219 --> 00:03:08,212 were previously free living bacteria that entered a partnership with bigger cells. 53 00:03:08,512 --> 00:03:12,635 They still have their own DNA and can multiply on their own, but 54 00:03:12,635 --> 00:03:16,372 they are not alive anymore; they are dead. 55 00:03:16,862 --> 00:03:20,478 So they traded their own life for the survival of their DNA, 56 00:03:20,478 --> 00:03:25,684 which means living things can evolve into dead things as long as it’s beneficial 57 00:03:25,684 --> 00:03:27,004 to their genetic code. 58 00:03:27,444 --> 00:03:33,279 So, maybe life is information that manages to ensure its continued existence. 59 00:03:33,679 --> 00:03:37,182 But what about AI (artificial intelligence)? 60 00:03:37,632 --> 00:03:42,444 By our most common definitions, we are very close to creating artificial life 61 00:03:42,444 --> 00:03:43,231 in computers. 62 00:03:43,611 --> 00:03:47,287 It’s just a question of time before the technology we build gets there. 63 00:03:47,707 --> 00:03:49,639 And this is not science fiction, either; 64 00:03:49,639 --> 00:03:53,069 there are a lot of smart people actively working on this. 65 00:03:53,069 --> 00:03:56,086 You could already argue that computer viruses are alive. 66 00:03:56,086 --> 00:03:59,778 Hm, okay. So what is life, then? 67 00:04:00,168 --> 00:04:04,420 Things, processes, DNA, information? 68 00:04:04,990 --> 00:04:07,535 This got confusing very fast. 69 00:04:08,085 --> 00:04:09,545 One thing is for sure: 70 00:04:09,545 --> 00:04:13,296 the idea that life is fundamentally different from non-living things 71 00:04:13,296 --> 00:04:15,951 because they contain some non-physical element 72 00:04:15,951 --> 00:04:19,515 or are governed by different principles than inanimate objects 73 00:04:19,515 --> 00:04:21,134 turned out to be wrong. 74 00:04:21,654 --> 00:04:26,110 Before Charles Darwin, humans drew a line between themselves and the rest 75 00:04:26,110 --> 00:04:30,878 of living things; there was something magical about us that made us special. 76 00:04:31,398 --> 00:04:35,936 Once we had to accept we are like every living being, a product of evolution, 77 00:04:35,936 --> 00:04:37,525 we drew a different line. 78 00:04:38,095 --> 00:04:41,636 But the more we learn about what computers can do and how life works, 79 00:04:41,636 --> 00:04:46,057 the closer we get to creating the first machine that fits our desciption of life, 80 00:04:46,057 --> 00:04:49,481 the more our image of ourselves is in danger again. 81 00:04:49,881 --> 00:04:51,828 And this will happen sooner or later. 82 00:04:52,348 --> 00:04:54,256 And here’s another question for you: 83 00:04:54,826 --> 00:04:57,796 if everything in the universe is made of the same stuff, 84 00:04:57,796 --> 00:05:00,570 does this mean everything in the universe is dead 85 00:05:00,570 --> 00:05:03,235 or that everything in the universe is alive? 86 00:05:03,875 --> 00:05:06,106 That it’s just a question of complexity? 87 00:05:06,566 --> 00:05:08,459 Does this mean we can never die 88 00:05:08,459 --> 00:05:10,676 because we were never alive in the first place? 89 00:05:11,136 --> 00:05:14,575 Is life and death an irrelevant question and we haven’t noticed it yet? 90 00:05:15,395 --> 00:05:19,588 Is it possible we are much more part of the universe around us than we thought? 91 00:05:20,488 --> 00:05:22,965 Don’t look at us; we don’t have any answers for you. 92 00:05:22,975 --> 00:05:25,163 Just questions for you to think about. 93 00:05:25,533 --> 00:05:29,732 After all, it’s thinking about questions like this that makes us feel alive 94 00:05:29,732 --> 00:05:31,794 and gives us some comfort.