0:00:00.218,0:00:03.850 Life is fundamentally different[br]from dead stuff—or is it? 0:00:04.090,0:00:07.567 Physicist Erwin Schrödinger[br]defined life this way: 0:00:07.567,0:00:12.314 Living things avoid decay into[br]disorder and equilibrium. 0:00:13.074,0:00:14.048 What does this mean? 0:00:14.508,0:00:17.361 Let’s pretend that your download[br]folder is the universe. 0:00:17.361,0:00:21.058 It started orderly and got more[br]and more chaotic over time. 0:00:21.678,0:00:25.466 By investing energy, you can create[br]order and clean it up. 0:00:25.926,0:00:27.490 This is what living things do. 0:00:27.920,0:00:29.778 But what is life? 0:00:36.564,0:00:39.457 Every living thing on this[br]planet is made of cells. 0:00:39.617,0:00:45.182 Basically, a cell is a protein-based robot[br]too small to feel or experience anything. 0:00:45.492,0:00:48.151 It has the properties we just[br]assign to life: 0:00:48.151,0:00:51.674 it has a wall that separates it from the[br]surroundings, creating order; 0:00:51.674,0:00:55.934 it regulates itself and maintains[br]a constant state; 0:00:55.934,0:00:58.280 it eats stuff to stay alive; 0:00:58.280,0:01:00.134 it grows and develops; 0:01:00.134,0:01:01.879 it reacts to the environment; 0:01:01.879,0:01:04.394 and it’s subject to evolution; 0:01:04.394,0:01:06.383 and it makes more of itself. 0:01:06.743,0:01:10.590 But of all the stuff that makes up[br]a cell, no part is alive. 0:01:10.960,0:01:15.087 Stuff reacts chemically with other stuff,[br]forming reactions 0:01:15.087,0:01:17.946 that start other reactions which[br]start other reactions. 0:01:18.446,0:01:23.206 In a single cell, every second several[br]million chemical reactions take place, 0:01:23.206,0:01:25.094 forming a complex orchestra. 0:01:25.584,0:01:28.405 A cell can build several thousand[br]types of protein: 0:01:28.405,0:01:31.809 some very simple, some complex[br]micromachines. 0:01:32.559,0:01:37.615 Imagine driving a car at 100 km/h while[br]constantly rebuilding every single 0:01:37.615,0:01:40.165 part of it with stuff you collect[br]from the street. 0:01:40.675,0:01:42.471 That is what cells do. 0:01:43.051,0:01:46.747 But no part of the cell is alive;[br]everything is dead matter 0:01:46.747,0:01:48.877 moved by the laws of the universe. 0:01:49.537,0:01:54.367 So is life the aggregate of all these[br]reaction processes that are taking place? 0:01:55.187,0:01:57.636 Eventually, every living thing will die. 0:01:58.336,0:02:02.791 The goal of the whole process is to[br]prevent this by producing new entities; 0:02:03.191,0:02:05.429 and by this, we mean DNA. 0:02:06.049,0:02:10.248 Life is, in a way, just a lot of stuff[br]that carries genetic information around. 0:02:10.778,0:02:12.826 Every living thing is subject to[br]evolution, 0:02:12.826,0:02:17.461 and the DNA that develops the best living[br]thing around it will stay in the game. 0:02:18.071,0:02:20.293 So, is DNA life, then? 0:02:20.863,0:02:25.553 If you take DNA out of its hull,[br]it certainly is a very complex molecule, 0:02:25.553,0:02:27.745 but it can’t do anything by itself. 0:02:28.235,0:02:31.790 This is where viruses make everything[br]more complicated. 0:02:32.100,0:02:36.256 They are basically strings of RNA[br]or DNA in a small hull 0:02:36.256,0:02:38.573 and need cells to do something. 0:02:38.573,0:02:41.305 We’re not sure if they count as[br]living or dead. 0:02:41.305,0:02:47.118 And still, there are 225,000,000 m³[br]of viruses on Earth. 0:02:47.118,0:02:49.385 They don’t seem to care what[br]we think of them. 0:02:49.385,0:02:53.723 There are even viruses that invade[br]dead cells and reanimate them 0:02:53.723,0:02:57.530 so they can be a host for them, which[br]blurs the line even more. 0:02:58.310,0:02:59.579 Or mitochondria. 0:02:59.949,0:03:03.219 They are the power plants of[br]most complex cells and 0:03:03.219,0:03:08.212 were previously free living bacteria that[br]entered a partnership with bigger cells. 0:03:08.512,0:03:12.635 They still have their own DNA and can[br]multiply on their own, but 0:03:12.635,0:03:16.372 they are not alive anymore; they are dead. 0:03:16.862,0:03:20.478 So they traded their own life for the[br]survival of their DNA, 0:03:20.478,0:03:25.684 which means living things can evolve into[br]dead things as long as it’s beneficial 0:03:25.684,0:03:27.004 to their genetic code. 0:03:27.444,0:03:33.279 So, maybe life is information that manages[br]to ensure its continued existence. 0:03:33.679,0:03:37.182 But what about AI[br](artificial intelligence)? 0:03:37.632,0:03:42.444 By our most common definitions, we are[br]very close to creating artificial life 0:03:42.444,0:03:43.231 in computers. 0:03:43.611,0:03:47.287 It’s just a question of time before the[br]technology we build gets there. 0:03:47.707,0:03:49.639 And this is not science fiction, either; 0:03:49.639,0:03:53.069 there are a lot of smart people[br]actively working on this. 0:03:53.069,0:03:56.086 You could already argue that computer[br]viruses are alive. 0:03:56.086,0:03:59.778 Hm, okay. So what is life, then? 0:04:00.168,0:04:04.420 Things, processes, DNA, information? 0:04:04.990,0:04:07.535 This got confusing very fast. 0:04:08.085,0:04:09.545 One thing is for sure: 0:04:09.545,0:04:13.296 the idea that life is fundamentally[br]different from non-living things 0:04:13.296,0:04:15.951 because they contain some[br]non-physical element 0:04:15.951,0:04:19.515 or are governed by different principles[br]than inanimate objects 0:04:19.515,0:04:21.134 turned out to be wrong. 0:04:21.654,0:04:26.110 Before Charles Darwin, humans drew a line[br]between themselves and the rest 0:04:26.110,0:04:30.878 of living things; there was something[br]magical about us that made us special. 0:04:31.398,0:04:35.936 Once we had to accept we are like every[br]living being, a product of evolution, 0:04:35.936,0:04:37.525 we drew a different line. 0:04:38.095,0:04:41.636 But the more we learn about what[br]computers can do and how life works, 0:04:41.636,0:04:46.057 the closer we get to creating the first[br]machine that fits our desciption of life, 0:04:46.057,0:04:49.481 the more our image of ourselves[br]is in danger again. 0:04:49.881,0:04:51.828 And this will happen sooner or later. 0:04:52.348,0:04:54.256 And here’s another question for you: 0:04:54.826,0:04:57.796 if everything in the universe is made[br]of the same stuff, 0:04:57.796,0:05:00.570 does this mean everything[br]in the universe is dead 0:05:00.570,0:05:03.235 or that everything in the universe[br]is alive? 0:05:03.875,0:05:06.106 That it’s just a question of complexity? 0:05:06.566,0:05:08.459 Does this mean we can never die 0:05:08.459,0:05:10.676 because we were never alive[br]in the first place? 0:05:11.136,0:05:14.575 Is life and death an irrelevant question[br]and we haven’t noticed it yet? 0:05:15.395,0:05:19.588 Is it possible we are much more part of[br]the universe around us than we thought? 0:05:20.488,0:05:22.965 Don’t look at us; we don’t have any[br]answers for you. 0:05:22.975,0:05:25.163 Just questions for you to think about. 0:05:25.533,0:05:29.732 After all, it’s thinking about questions[br]like this that makes us feel alive 0:05:29.732,0:05:31.794 and gives us some comfort.