0:06 [Applause]
0:12 so when I took my first physics class I
0:15 was at Community College and I was just
0:17 absolutely floored by the idea that we
0:20 could describe the world with simple and
0:23 elegant mathematical equations it just
0:27 amazed me and so I cast aside my 17
0:31 magazines in favor of reading books that
0:34 were about theoretical physics
0:36 now I'm an astrobiologist and I study
0:39 life I'm interested in life here on
0:41 earth and I'm also interested in life
0:43 out there among the stars if we can find
0:45 it and that's really cool except the
0:52 problem is we don't really understand
0:53 what life is and so I'm interested and
0:55 whether we actually have a theory of
0:57 life if we could find a theory of life
0:58 and what its basis would be and we're
1:01 not there yet but I think that we have
1:03 some clues and there might actually be
1:05 such a unified theory of life and if
1:07 there is at its core information has to
1:10 be key so in physics we have lots of
1:14 elegant theories and a lot of the time
1:16 nowadays you're going to hear people
1:17 talking about a theory of everything
1:19 something that unifies gravity with our
1:22 theories of quantum physics and so we
1:25 have lots of theories of the quantum
1:26 world and we have gravity we put them
1:28 together we will explain everything but
1:32 there's a problem the theory of
1:34 everything is a theory of everything
1:37 except those things that theorized it
1:40 explains nothing about us and so for me
1:44 the thing that's most interesting about
1:46 our theories of the world is that human
1:48 beings living breathing entities could
1:50 write them down at all so I drew this
1:54 picture myself sometimes I like to be an
1:57 artist it wasn't with crayons but this
2:00 is Newton's law of gravitation so to be
2:02 more perfectly accurate I should have
2:03 put the Einstein equation up here but
2:04 this one is more fun to play with so for
2:07 me this is beautiful this is a work of
2:08 art but it's also beautiful because of
2:10 the equation that equation describes a
2:13 lot about our world it describes an
2:16 apple falling from a tree and the motion
2:18 of
2:19 around our Sun that unification is
2:23 beautiful we can predict those things
2:25 with the same mathematical equation it
2:28 contains a lot of information when we
2:32 look up at our night sky we see the
2:34 stars and we see motion among those
2:37 stars the planets when Newton came up
2:39 with his theory of gravitation it was
2:41 the first time that we could explain
2:42 that and not only could we explain it
2:45 but we could explain the reason I jump
2:47 up and fall down with the same reason
2:50 that we see a comment take a particular
2:51 trajectory on our night sky that is
2:54 beautiful
2:56 now most people don't look at equations
2:58 and think equations are beautiful
3:00 they'll look at something like this and
3:02 think it's beautiful and this is
3:04 beautiful
3:05 this is the Mona Lisa of course and the
3:08 Mona Lisa is one of the most famous
3:10 paintings in the world how much
3:12 information is in that smile how much
3:14 does it make you feel there's a ton of
3:16 information in this painting this is art
3:19 but why is this art what makes this
3:22 thing evoke such a response in us to
3:24 feel something when we look at this
3:26 image I could take the same pixels on
3:28 this painting and I could randomize them
3:31 and suddenly all that information is
3:34 lost it's not art I could do that and
3:41 make any almost an infinite number of
3:45 possible Mona Lisa's just using those
3:47 pixels of paint but only some of them
3:49 evoke that same response only some of
3:52 them we would call art so on this image
3:54 I have here on the right is information
3:56 on the left is entropy and if we think
3:59 about the space of all possible
4:01 configurations of those pixels only some
4:04 of them are information only some of
4:06 them mean something to us we have a
4:09 similar problem in physics and being
4:11 physicists we can be somewhat dramatic
4:13 we think about the problem of what
4:14 exists I mean most people don't think
4:16 about physicists flying around worrying
4:17 about what exists but we do but we do it
4:20 in kind of a more precise way we worry
4:22 about why some mathematical equations
4:25 correspond to the physical world and
4:27 describe reality and others don't why do
4:30 some equations work in other stone
4:33 one possible resolution is to propose
4:39 that all mathematical equations can
4:41 correspond to something that exists
4:43 somewhere and this is the mathematical
4:45 universe hypothesis first proposed by
4:48 Max Tegmark so the idea is everything
4:51 that you can write down as an equation
4:53 exists but by trying to explain
4:55 everything you've effectively explained
4:58 nothing and if we think about art I
5:02 don't think anyone would buy that every
5:06 possible arrangement of pixels on a
5:08 canvas is art there's something that
5:11 separates art from things that don't
5:13 evoke the same kind of response so when
5:16 we think about the question what is art
5:17 art is something that makes us feel
5:20 something it changes the way we think
5:22 about the world what is math to physics
5:27 well math to physics is the same way
5:29 usually when we think in about an
5:31 equation like Newton's equation we think
5:33 the power and beauty of it is the
5:35 ability to predict the world but the
5:37 true beauty and power of that equation
5:39 its ability to change the world to
5:41 create things to innovate and here's
5:44 just one example of what our knowledge
5:46 of the laws of gravitation have done we
5:48 are the only planet in the solar system
5:50 with a halo of artificial satellites we
5:53 are the only planet that is anti
5:54 accreting we are throwing stuff into
5:57 space that is a creative process earth
6:04 without a technological civilization has
6:07 no satellites earth with it has
6:10 satellites the dividing line is that
6:13 earth has systems that generate
6:17 information use information to create
6:19 new possibilities information changes
6:22 the world and if you don't believe me
6:25 you've probably been living under a rock
6:27 because we live in the information age I
6:30 am sure everyone listening to this talk
6:32 has a cell phone or a device nearby and
6:35 for those of you in the room tonight you
6:37 are probably going to check that device
6:39 when you leave here you are going to
6:41 check your email you're going to get a
6:42 text from a friend that is going to
6:44 change or help decide what you
6:45 do after it changes you you are impacted
6:47 by information every day so when we get
6:51 to the question that I'm absolutely
6:53 obsessed about what is life this is the
6:56 key story information information is the
6:59 thing that living systems are doing that
7:01 no other physical system that we know
7:02 about is even coming close to doing so
7:06 the question what his life has been a
7:07 question that physicists have been
7:08 asking for a long time since Aaron
7:10 Schrodinger first posed the question to
7:12 physicist in a particular way that made
7:14 it a question for physics in 1944 and
7:18 we're not there yet but we're getting
7:19 closer and so as an astrobiologist I
7:22 care what separates a nonliving world
7:24 from a living world and our living world
7:26 is distinct because of all the
7:29 information processing systems on its
7:30 surface and you may say well Sara so far
7:34 you've been talking about technological
7:36 civilizations surely that's an extreme
7:38 example that's not really what life is
7:40 that's an example of life and so just to
7:43 relate it back to biology I'm going to
7:44 give one more example which is the
7:46 example of a slime mold and so what I
7:49 have here is a picture of Tokyo and a
7:51 picture of a slime mold they were
7:55 remarkably similar and that's actually
7:57 not by coincidence it's actually by the
8:02 algorithms that these systems came up
8:05 with to solve the same problem and so
8:08 when Cho Kyo was planned as a city the
8:11 engineers had to develop a subway and
8:13 the subway stations were in particular
8:14 locations and the city got designed
8:17 around where those locations were people
8:19 want to neat be near Subway's the slime
8:22 mold those little dots their food
8:25 sources and they were arranged in the
8:28 same manner as the subway station
8:29 stations in Tokyo and both systems came
8:32 up with a similar plan for the solution
8:34 they came up with a similar algorithm a
8:36 similar informational solution to the
8:38 problem at hand
8:39 this is ubiquitous in biology and so
8:43 when most people think about explanatory
8:45 frameworks for thinking about life and
8:47 understanding life they think about
8:48 evolution they think about Darwin's
8:50 theories and I just want to make a last
8:52 point that information is absolutely
8:54 critical to understanding why Darwin
8:56 works at all and so to illustrate that
8:59 we do a little experiment this was
9:02 actually an experiment done in the lab
9:04 it's called the Spiegelman's monster
9:05 after the scientists Spiegelman that
9:07 performed the experiment he took a virus
9:09 and he put it in a test tube and
9:11 selected it on it so he did Darwinian
9:13 evolution select for this thing to be
9:15 able to copy itself and did that
9:17 iteratively the thing that he got out
9:19 was not a more complex system a more
9:23 complex virus it was a very simple one
9:27 why was it simple it was evolving it
9:32 should be getting more interesting over
9:33 time well the reason it was more simple
9:35 it's because in real living systems
9:38 they're open they're getting information
9:41 constantly from in our environment
9:42 they're getting information from each
9:43 other in the test tube it was a closed
9:46 system there was no information being
9:48 input to that system and when we think
9:50 about the way we're designing
9:51 experiments for origins of life in the
9:53 lab we're always studying closed systems
9:56 they're in a test tube this may be one
9:58 reason that we haven't solved the origin
9:59 of life yet we need the information
10:02 input into the system and so when I'm
10:05 thinking about living systems this
10:07 information aspect is absolutely
10:09 critical and so on the bottom here shown
10:11 DNA right on the one side we see things
10:16 that are random on the other side we see
10:18 things that are information we think
10:20 about DNA our genome it contains
10:22 information right it's the information
10:24 that we pass on to our children but the
10:27 information there is also critically
10:29 important to performing transformations
10:30 in the cell it's actually what tells our
10:32 cell how's work it's the same kind of
10:34 way that some mathematical equations are
10:36 some pieces of our information they do
10:38 something to the world they create
10:40 things they innovate and so the very
10:42 essence of what living systems are what
10:44 they do is informational in nature they
10:47 use information to create new
10:49 possibilities and to innovate and that
10:52 is the story of life
10:56 [Applause]