WEBVTT 00:00:00.218 --> 00:00:03.850 Life is fundamentally different from dead stuff—or is it? 00:00:04.090 --> 00:00:07.567 Physicist Erwin Schrödinger defined life this way: 00:00:07.567 --> 00:00:12.314 Living things avoid decay into disorder and equilibrium. 00:00:13.074 --> 00:00:14.048 What does this mean? 00:00:14.508 --> 00:00:17.361 Let’s pretend that your download folder is the universe. 00:00:17.361 --> 00:00:21.058 It started orderly and got more and more chaotic over time. 00:00:21.678 --> 00:00:25.466 By investing energy, you can create order and clean it up. 00:00:25.926 --> 00:00:27.490 This is what living things do. 00:00:27.920 --> 00:00:29.778 But what is life? 00:00:36.564 --> 00:00:39.457 Every living thing on this planet is made of cells. 00:00:39.617 --> 00:00:45.182 Basically, a cell is a protein-based robot too small to feel or experience anything. 00:00:45.492 --> 00:00:48.151 It has the properties we just assign to life: 00:00:48.151 --> 00:00:51.674 it has a wall that separates it from the surroundings, creating order; 00:00:51.674 --> 00:00:55.934 it regulates itself and maintains a constant state; 00:00:55.934 --> 00:00:58.280 it eats stuff to stay alive; 00:00:58.280 --> 00:01:00.134 it grows and develops; 00:01:00.134 --> 00:01:01.879 it reacts to the environment; 00:01:01.879 --> 00:01:04.394 and it’s subject to evolution; 00:01:04.394 --> 00:01:06.383 and it makes more of itself. 00:01:06.743 --> 00:01:10.590 But of all the stuff that makes up a cell, no part is alive. 00:01:10.960 --> 00:01:15.087 Stuff reacts chemically with other stuff, forming reactions 00:01:15.087 --> 00:01:17.946 that start other reactions which start other reactions. 00:01:18.446 --> 00:01:23.206 In a single cell, every second several million chemical reactions take place, 00:01:23.206 --> 00:01:25.094 forming a complex orchestra. 00:01:25.584 --> 00:01:28.405 A cell can build several thousand types of protein: 00:01:28.405 --> 00:01:31.809 some very simple, some complex micromachines. 00:01:32.559 --> 00:01:37.615 Imagine driving a car at 100 km/h while constantly rebuilding every single 00:01:37.615 --> 00:01:40.165 part of it with stuff you collect from the street. 00:01:40.675 --> 00:01:42.471 That is what cells do. 00:01:43.051 --> 00:01:46.747 But no part of the cell is alive; everything is dead matter 00:01:46.747 --> 00:01:48.877 moved by the laws of the universe. 00:01:49.537 --> 00:01:54.367 So is life the aggregate of all these reaction processes that are taking place? 00:01:55.187 --> 00:01:57.636 Eventually, every living thing will die. 00:01:58.336 --> 00:02:02.791 The goal of the whole process is to prevent this by producing new entities; 00:02:03.191 --> 00:02:05.429 and by this, we mean DNA. 00:02:06.049 --> 00:02:10.248 Life is, in a way, just a lot of stuff that carries genetic information around. 00:02:10.778 --> 00:02:12.826 Every living thing is subject to evolution, 00:02:12.826 --> 00:02:17.461 and the DNA that develops the best living thing around it will stay in the game. 00:02:18.071 --> 00:02:20.293 So, is DNA life, then? 00:02:20.863 --> 00:02:25.553 If you take DNA out of its hull, it certainly is a very complex molecule, 00:02:25.553 --> 00:02:27.745 but it can’t do anything by itself. 00:02:28.235 --> 00:02:31.790 This is where viruses make everything more complicated. 00:02:32.100 --> 00:02:36.256 They are basically strings of RNA or DNA in a small hull 00:02:36.256 --> 00:02:38.573 and need cells to do something. 00:02:38.573 --> 00:02:41.305 We’re not sure if they count as living or dead. 00:02:41.305 --> 00:02:47.118 And still, there are 225,000,000 m³ of viruses on Earth. 00:02:47.118 --> 00:02:49.385 They don’t seem to care what we think of them. 00:02:49.385 --> 00:02:53.723 There are even viruses that invade dead cells and reanimate them 00:02:53.723 --> 00:02:57.530 so they can be a host for them, which blurs the line even more. 00:02:58.310 --> 00:02:59.579 Or mitochondria. 00:02:59.949 --> 00:03:03.219 They are the power plants of most complex cells and 00:03:03.219 --> 00:03:08.212 were previously free living bacteria that entered a partnership with bigger cells. 00:03:08.512 --> 00:03:12.635 They still have their own DNA and can multiply on their own, but 00:03:12.635 --> 00:03:16.372 they are not alive anymore; they are dead. 00:03:16.862 --> 00:03:20.478 So they traded their own life for the survival of their DNA, 00:03:20.478 --> 00:03:25.684 which means living things can evolve into dead things as long as it’s beneficial 00:03:25.684 --> 00:03:27.004 to their genetic code. 00:03:27.444 --> 00:03:33.279 So, maybe life is information that manages to ensure its continued existence. 00:03:33.679 --> 00:03:37.182 But what about AI (artificial intelligence)? 00:03:37.632 --> 00:03:42.444 By our most common definitions, we are very close to creating artificial life 00:03:42.444 --> 00:03:43.231 in computers. 00:03:43.611 --> 00:03:47.287 It’s just a question of time before the technology we build gets there. 00:03:47.707 --> 00:03:49.639 And this is not science fiction, either; 00:03:49.639 --> 00:03:53.069 there are a lot of smart people actively working on this. 00:03:53.069 --> 00:03:56.086 You could already argue that computer viruses are alive. 00:03:56.086 --> 00:03:59.778 Hm, okay. So what is life, then? 00:04:00.168 --> 00:04:04.420 Things, processes, DNA, information? 00:04:04.990 --> 00:04:07.535 This got confusing very fast. 00:04:08.085 --> 00:04:09.545 One thing is for sure: 00:04:09.545 --> 00:04:13.296 the idea that life is fundamentally different from non-living things 00:04:13.296 --> 00:04:15.951 because they contain some non-physical element 00:04:15.951 --> 00:04:19.515 or are governed by different principles than inanimate objects 00:04:19.515 --> 00:04:21.134 turned out to be wrong. 00:04:21.654 --> 00:04:26.110 Before Charles Darwin, humans drew a line between themselves and the rest 00:04:26.110 --> 00:04:30.878 of living things; there was something magical about us that made us special. 00:04:31.398 --> 00:04:35.936 Once we had to accept we are like every living being, a product of evolution, 00:04:35.936 --> 00:04:37.525 we drew a different line. 00:04:38.095 --> 00:04:41.636 But the more we learn about what computers can do and how life works, 00:04:41.636 --> 00:04:46.057 the closer we get to creating the first machine that fits our desciption of life, 00:04:46.057 --> 00:04:49.481 the more our image of ourselves is in danger again. 00:04:49.881 --> 00:04:51.828 And this will happen sooner or later. 00:04:52.348 --> 00:04:54.256 And here’s another question for you: 00:04:54.826 --> 00:04:57.796 if everything in the universe is made of the same stuff, 00:04:57.796 --> 00:05:00.570 does this mean everything in the universe is dead 00:05:00.570 --> 00:05:03.235 or that everything in the universe is alive? 00:05:03.875 --> 00:05:06.106 That it’s just a question of complexity? 00:05:06.566 --> 00:05:08.459 Does this mean we can never die 00:05:08.459 --> 00:05:10.676 because we were never alive in the first place? 00:05:11.136 --> 00:05:14.575 Is life and death an irrelevant question and we haven’t noticed it yet? 00:05:15.395 --> 00:05:19.588 Is it possible we are much more part of the universe around us than we thought? 00:05:20.488 --> 00:05:22.965 Don’t look at us; we don’t have any answers for you. 00:05:22.975 --> 00:05:25.163 Just questions for you to think about. 00:05:25.533 --> 00:05:29.732 After all, it’s thinking about questions like this that makes us feel alive 00:05:29.732 --> 00:05:31.794 and gives us some comfort.