00:00:11.840 Welcome to Topcast and Episode 3, or Part 3, rather, of Chapter 1, The Theory of Everything
00:00:18.880 from the Fabric of Reality by David Deutsch. Before I begin, a little note on my setup,
00:00:24.720 some people have been saying that it's a bit distracting when I am actually reading from one of
00:00:29.440 the books that I read from, because I'm not staring straight into the screen. I'm going to
00:00:34.800 try and remedy this, if anyone has any ideas for me about precisely how to go about doing that,
00:00:40.000 so it's not so distracting. I'd be happy to hear them, but one of the reasons it hasn't been a
00:00:44.560 priority is because the overwhelming majority of people actually only listen, they don't actually
00:00:49.840 watch. I think the downloads from the podcast version, the audio only version, are like 10 times
00:00:57.200 greater than the views that I get on YouTube. It would be so much more simple, efficient if I
00:01:05.840 didn't bother putting together the video, because the video actually takes a lot longer to edit
00:01:10.320 and all that sort of stuff, audio is much easier to deal with. Nonetheless, I like doing the video,
00:01:15.440 so I'm going to persevere with that. If you have any ideas about how I can read by doing this,
00:01:22.240 which is me looking at the screen right now, while simultaneously looking straight at the camera
00:01:27.920 I would appreciate it. I use an iPhone, one of the more recent iPhones, or iPhone 11, in order to
00:01:35.280 actually record the video and the audio goes into that. Don't need to go into the technical details,
00:01:39.840 but anyway, if you have an idea for how I can fix the way in which I look at the camera whilst
00:01:46.560 simultaneously reading, then that would be great. I know I think called an AutoQ Exists, but presumably
00:01:52.720 that's quite a professional piece of gear. Anyway, no more preamble. Let me get into the reading
00:01:59.760 for today, and we're getting very close to the end of the chapter. It's a very fun part of the
00:02:04.960 end of the chapter, because we start to encounter some real seeds, and I'm going to mention that
00:02:10.640 word a few times today, real seeds of the science of Canon cards, which is sitting there behind me
00:02:17.920 by Chiara Maleta, the beginnings of constructor theory. They're right here in the fabric of reality,
00:02:24.720 and so I'm going to concentrate a little on that today, not only in the fabric of reality,
00:02:30.160 in the first few pages of the fabric of reality. So let's go, and I'm at the point where David
00:02:38.160 says on page 23, quote, in the reductionist worldview, the laws governing subatomic particle interactions
00:02:46.240 are of paramount importance, as they are the base of the hierarchy of all knowledge. But in the
00:02:52.960 real structure of scientific knowledge, and in the structure of knowledge of reality,
00:02:57.520 such laws have a much more humble role, what is that role? It seems to me that none of the
00:03:04.240 candidates for a theory of everything that has yet been contemplated contains much that is new
00:03:10.800 by way of explanation, perhaps the most innovative approach from the explanatory point of view
00:03:16.880 is super string theory, in which extended objects, strings rather than point like particles
00:03:23.440 are the elementary building blocks of matter. But no existing approach offers an entirely new
00:03:29.520 mode of explanation, new in the sense of Einstein's explanation of gravitational forces in terms
00:03:36.240 of curved space and time pausing there, just my reflection on this. So David has said right there
00:03:45.360 that nothing about the other conceptions of the way in which we might improve physics off into
00:03:53.840 the infinite future, string theory is one such, is a new mode of explanation. This term,
00:04:00.000 mode of explanation is right there at the beginning of the fabric of reality. And that's remarkable,
00:04:05.120 because here in 1997, we have the motivation for constructive theory. We have the phrase
00:04:11.920 mode of explanation. We can see those seeds. As I've talked about in previous episodes for the
00:04:17.200 fabric of reality, for what is happening right now over the last few years and right now in 2021,
00:04:23.600 it's almost like a prediction of the content of future knowledge isn't it? Not quite. That's a joke
00:04:28.560 of course, but it's clear David is appealing for a new way forward in physics. It seems like
00:04:33.840 no one else really took up the mantle between 1997 through to today. So he did and Kiara and others.
00:04:43.680 And it's another good reason for me to be doing this book right now alongside Kiara's book.
00:04:48.160 Here we are getting the appeal for that new fundamental theory. And there in Kiara's book,
00:04:54.880 we are getting the description and explanation of what has been accomplished so far with this
00:05:01.200 exact new theory constructor theory. So it's a wonderful symmetry between the two books back to
00:05:08.640 this book, the fabric of reality. And David writes, quote, in fact, the theory of everything is
00:05:15.200 expected to inherit virtually its entire explanatory structure. It's physical concepts,
00:05:20.320 its language, its mathematical formalism, and the form of explanations from the existing theories
00:05:25.520 of electromagnetism, nuclear forces, and gravity. Therefore, we may look to this underlying structure,
00:05:32.800 which we already know from existing theories for the contribution of fundamental physics to
00:05:37.840 our overall understanding. There are two theories in physics, which are considerably deeper than
00:05:44.160 all others. The first is the general theory of relativity, which, as I have said, is our best
00:05:49.760 theory of space, time, and gravity. The second quantum theory is even deeper. Between them,
00:05:57.120 these two theories, and not any existing or currently envisaged theory of subatomic particles,
00:06:02.800 provide the detailed explanatory and formal framework within which all other theories and modern
00:06:08.800 physics are expressed. And they contain overarching physical principles to which all other
00:06:13.360 theories conform. A unification of general relativity and quantum theory to give a quantum theory of
00:06:19.280 gravity has been a major quest of theoretical physicists for several decades and would have to form
00:06:25.360 part of any theory of everything in either the narrow or the broad sense of the term.
00:06:31.360 As we shall see in the next chapter, quantum theory, like relativity, provides a revolutionary
00:06:37.600 new mode of explanation of physical reality. The reason why quantum theory is the deeper of the two,
00:06:43.040 lies more outside physics than within it. For its ramifications, they are very wide,
00:06:48.240 extending far beyond physics, and even beyond science itself, as it is normally conceived,
00:06:53.440 okay, pausing there just my reflection on this. So yes, quantum theory is the deeper of the two.
00:07:00.400 We've got general relativity and we've got quantum theory, both of which purport to be
00:07:05.920 explanations of the universe as a whole in a certain sense. The reason why quantum theory
00:07:12.960 is the deeper of the two is because it affects other areas of our knowledge more so than what
00:07:20.400 general relativity seems to. In another video that I did called The Nexus, which was some personal
00:07:27.440 musings on the nature of personhood, I tried to describe what the implications are of our most modern
00:07:35.440 understanding of quantum theory upon this question of what it means to be a person.
00:07:41.920 Because we exist in a multiverse and the multiverse consists of these interesting entities
00:07:48.720 called fungible things, okay, so fungibility is this idea of where a particle or even a larger
00:07:57.760 object and ensemble of particles, which includes something like a human body, is extended across
00:08:03.120 the multiverse. And so in order to understand the nature of personhood more fully, you need to
00:08:08.240 grapple with quantum theory. So I think quantum theory absolutely has deep implications for the
00:08:14.000 nature of personhood. It also, of course, has ramifications for the field of computation. And this
00:08:20.080 is what David Deutsch actually proved in his famous 1986 paper, one of the things he's most
00:08:27.360 famous for beyond writing books is this particular proof that he did, this proof of the possibility,
00:08:33.760 the physical possibility of quantum computation, which means that now computation is truly a part
00:08:40.480 of physics. So quantum theory has got ramifications there and therefore it's also got ramifications
00:08:46.000 for mathematics because it provides a limit constraints on what can be proved given those quantum
00:08:54.080 mechanical laws. So because quantum mechanical laws are universal, they apply to everything in the
00:09:00.560 universe, including the brains of mathematicians, it limits what those brains of those mathematicians
00:09:07.280 can do or what computers can do that are made out of matter. And so quantum theory has this
00:09:13.440 reach into mathematics, even into pure mathematics because it is the very thing which tells you
00:09:23.200 what laws, computers, things that prove stuff, which includes human brains can do what they
00:09:29.040 are able to do. And then it also reaches therefore into epistemology, beyond mathematics because it
00:09:36.960 provides constraints on our ability to perfectly know anything at all. We are necessarily
00:09:44.400 fallible because we're error prone human beings due to just making mistakes, but those mistakes
00:09:50.160 are also embedded there in the laws of physics. And related to this, quantum theory mandates that
00:09:58.000 not everything can be known simultaneously, that matter behaves in ways governed by quantum
00:10:03.680 mechanical laws such that we have to rule out epistemic certainty or in simple language,
00:10:09.840 no, you cannot be sure of anything. You can have good explanations, but they must remain fallible,
00:10:16.080 even the contents of your own memory must remain fallible, given quantum theory among other things.
00:10:22.560 And so that has ramifications for psychology. And so it goes. So these are just some of the
00:10:28.480 senses in which quantum theory has implications for all those other areas that we typically
00:10:35.760 partition off from the rest of science. Okay, back to the book and David writes, quantum theory
00:10:42.400 is one of what I shall call the four main strands of which our current understanding of the
00:10:48.480 fabric of reality is composed. Before I say what the other three strands are, I must mention
00:10:54.080 another way in which reductionism misrepresent the structure of scientific knowledge. Not only does
00:11:00.320 it assume that explanation always consists of analyzing a system into smaller simpler systems,
00:11:06.080 it also assumes that all explanation is of later events in terms of earlier events. In other
00:11:11.360 words, that the only way of explaining something is to state its causes and this implies that the
00:11:17.200 earlier the events in terms of which we explain something, the better the explanation. So that
00:11:22.480 ultimately the best explanations of all are in terms of the initial state of the universe,
00:11:27.520 supposing there, they were getting constructive theory again. This idea that the best explanations
00:11:32.960 are in terms of something that happened earlier that caused something to happen later is of course,
00:11:38.720 all this dynamical laws and initial conditions vision of physics. This are kind of narrow way
00:11:45.360 of viewing the way in which the universe evolves over time of the way in which change happens
00:11:52.240 at all in the universe. Back to the book David writes,
00:11:56.240 A theory of everything which excludes a specification of the initial state of the universe is not
00:12:00.960 a complete description of physical reality because it provides only laws of motion and laws of
00:12:06.080 motion by themselves make only conditional predictions that is they never state categorically what
00:12:11.680 happens but only what will happen at one time given what was happening at another time.
00:12:17.440 Only if a complete specification of the initial state is provided can a complete description of
00:12:22.720 physical reality in principle be deduced pausing their my reflection again. So I have heard
00:12:30.560 theoretical physicists specifically particle physicists say that the deeper theory of everything
00:12:37.040 would be one that would provide the initial conditions in some way as a matter of necessity
00:12:43.760 like mathematical necessity. Now I suppose that's one way to go. Of course,
00:12:49.760 all you then get out of that so-called theory of everything is again this reductionist idea
00:12:54.880 that gives you that would give you the initial conditions and then the dynamical laws presumably
00:12:59.360 and you would have this the deeper theory this deeper mathematical theory that says
00:13:03.200 well these initial conditions can only be in such and such a way but whatever that theory is that
00:13:08.400 gives you these initial conditions of the universe you might ask of that theory why it has the form
00:13:13.920 that it does. I suppose you get into some kind of infinite regress then I don't know exactly how
00:13:19.520 they resolve this. Anyways, whatever the case, David in that passage there and in the next few
00:13:25.360 passages is really emphasizing this idea that this initial conditions dynamical laws kind of thing
00:13:33.040 that the laws of motion and initial conditions problem doesn't seem to be able to provide a true
00:13:39.520 theory of everything. So he's really providing clues there for someone else had they wanted to create
00:13:47.200 constructor theory. It reminds me a little bit of another book that I've read recently called
00:13:52.400 from 0 to 1 which is by the entrepreneur Peter Thiel. If you don't know who he is he's Elon Musk's
00:13:59.040 sort of off-sider he's another billionaire he was Elon Musk's off-sider he worked on PayPal and
00:14:04.320 so on. Smart guy businessman anyway his book from 0 to 1 is about how to create a business or a
00:14:11.280 startup. Young people come up to him and want to know how to become rich themselves by creating a new
00:14:17.040 business they seem to be after the recipe the algorithm. Of course his advice is he can't possibly
00:14:23.360 tell you that because there is no such algorithm there is no recipe. If it were that simple then
00:14:30.320 everyone would just follow the recipe and become rich but that's the very point about creativity.
00:14:35.840 Similarly physicists want to make fundamental breakthroughs they need creativity here in the fabric
00:14:43.120 of reality we've got the same thing there are clues here for the taking for anyone who might have
00:14:49.200 wanted to conceive of a new mode of explanation. But the thing is with any of this stuff
00:14:57.360 it has to be a very personal thing it has to be part of your personal problem situation as
00:15:03.360 Papa might put it unless you are truly really invested in the problem then you won't spend much
00:15:10.320 time thinking about it. David did of course so much that he wrote a book on it and then he went on
00:15:16.160 to begin to solve the problems that he is laying out here in constructive theory. The point is
00:15:22.480 anyone can do it they just have to choose to do it and become interested in it but most won't.
00:15:30.000 Most won't actually be that genuinely interested even people with physics degrees. I have a physics
00:15:35.520 degree. It doesn't mean anything in terms of trying to create fundamental theories because that's
00:15:41.200 not part of my problem situation. I'm genuinely not deeply interested enough. I'm more interested
00:15:47.760 in for example in my particular problem situation trying to explain ideas that have already been
00:15:54.400 discovered in new ways so that people out there who have a casual interest can to some extent level up
00:16:01.040 and learn more about this and perhaps then develop a really deep interest in it. I think that's
00:16:07.120 what sort of my function is in this. I don't have any illusions that I'm going to make deep breakthroughs
00:16:13.200 here but maybe someone listening will be enticed to go off and read the details read the technical
00:16:19.440 details and then they perhaps will make some of the more fundamental breakthroughs. It all depends
00:16:25.280 on what you find fun doing. I have fun just talking about this and solving the problem of
00:16:33.360 trying to explain it with ever more clarity in more and more simple terms to the extent that I can.
00:16:40.240 But what I notice sometimes is that well I'll just say it sometimes people seem to
00:16:45.920 kid themselves. I see this in physics to some extent. People who say they either want to be
00:16:52.560 physicists want to make breakthroughs. They're already in physics but you dig a little and it's
00:16:58.880 quickly apparent that this is not how their life is quite set up. They're actually invested
00:17:04.880 rather more in other things. They have other interests as well. They have other problems and that's
00:17:09.840 perfectly fine but there might be something that psychologists call to the extent that it exists
00:17:15.680 cognitive dissonance. Not really being aware that your explicit words about what you're trying to
00:17:21.440 achieve don't quite match up to what you're doing day to day in reality behind the scenes to put
00:17:27.920 this another way. Einstein it might have been thought while he was working at a patent office
00:17:34.240 was just working on relativity as a kind of hobby but that would be to misunderstand what was going on.
00:17:40.960 So many of his waking moments were devoted solely to figuring out these problems. He was
00:17:46.720 obsessed by the fun of finding this stuff out and later on being a physicist wasn't a job that
00:17:52.400 he clocked into and worked up until morning tea and then clocked off again and then went back to
00:17:59.680 work at his desk for another few hours while checking emails and so on. No. He was utterly
00:18:06.400 obsessed with figuring out specific problems and he made progress because he was passionate
00:18:12.160 and he found joy in solving these particular problems and there's a difference there between
00:18:18.400 that kind of approach towards problem solving in a specific area and those who might say that
00:18:26.000 that's what they want to do but instead splitting their attention and their fun between
00:18:32.480 many other things and of course that's totally fine this is not a judgment it is the difference
00:18:37.280 between being able to because you have a finite amount of attention and a finite amount of
00:18:43.520 creativity given a certain amount of finite time in order to solve particular problems and if
00:18:50.720 you are utterly obsessed with certain problems then you're probably going to make you're possibly
00:18:54.880 going to make more progress there than someone who is not quite so obsessed. That's my diversion
00:19:03.040 on the psychology of making progress in physics and in elsewhere. I don't do it often and I'm not
00:19:11.600 about to be doing it often here either so let's go back to the book and David writes.
00:19:19.120 Current cosmological theories do not provide a complete specification of the initial state even
00:19:24.160 in principle but they do say that the universe was initially very small very hot and very uniform
00:19:29.600 in structure. We also know it cannot have been perfectly uniform because that would be incompatible
00:19:36.240 according to the theory with the distribution of galaxies we observe across the sky today.
00:19:41.680 The initial variations in density lumpiness would have been greatly enhanced by gravitational clumping
00:19:48.960 that is relatively dense regions would have attracted more matter and become denser so they
00:19:55.360 need only have been very slight initially pausing their yes my reflection this this lumpiness
00:20:02.400 was a mystery for some time it was a it was a mystery until the Kobe the the satellite satellite
00:20:11.680 telescope called the cosmic microwave background explorer which took the first images somewhere
00:20:18.080 between 1989 and 1993 of the cosmic microwave background the heat left over after the big bang.
00:20:26.480 Now prior to Kobe the thing was that wherever we pointed out telescopes effectively temperature
00:20:34.960 probes at the sky we found exactly the same temperature everywhere 2.3 above absolute zero 2.3
00:20:43.440 Kelvin or 2.3 degrees Celsius above absolute zero the minimum possible temperature so the
00:20:48.560 universe is bathed in this heat but it's extremely uniform and that is that's kind of a problem it's
00:20:55.520 a problem because the universe itself when you look in the visual band or in any other band
00:21:01.680 aside from the microwave band if you're looking if you're looking at things other than at that
00:21:06.480 temperature you find lumpiness as David says here and this is in fact what the astronomers and
00:21:12.080 the astrophysicist talk about the cosmologist talk about I talk about the lumpiness of the universe
00:21:17.600 there are regions where there are galaxies that's a lump and the region between galaxies which have
00:21:22.480 nothing at all but why is the distribution of matter the way that it is given the cosmic microwave
00:21:27.520 background is not lumpy well the cosmic microwave background explorer this satellite that was
00:21:33.520 put up there in the late 80s early 90s revealed that in fact the cosmic microwave background
00:21:43.200 is lumpy after all it's not perfectly uniform it has these regions of cooler and warmer
00:21:51.600 and the cooler areas are going to be the places where in the early universe the matter would have
00:21:58.400 been attracted towards that's where it would have collapsed and in the warmer areas where the
00:22:03.760 matter would have expanded out so you get the voids in the area where you get a higher temperature
00:22:09.360 and in the cooler areas that's where the galaxies form and that's where the stars form that's
00:22:13.200 where your your glowing matter forms and and and and this is this is our George Smoot
00:22:19.120 was awarded the Nobel Prize for this although his student is Charlie Langweaver that I've talked
00:22:25.600 about very very often it was his research student his PhD student at the time I think it was his
00:22:30.560 PhD student might have been his graduate student anyway Charlie Langweaver the great Charlie Langweaver
00:22:36.080 he's also one of these physicists not on social media which is a great shame he's got this
00:22:41.280 wonderful list of papers that that stretch from biology and cancer through to cosmology and
00:22:48.160 astrophysics and planetary science and all this sort of great stuff and he's a great speaker as well
00:22:52.720 you can find him on youtube and I always talk him up because he was my lecturer and so he tells the
00:22:59.600 story about how he was actually the one that processed the data and he was looking for that
00:23:06.160 data from the cosmic microwave background explorer and it was something like 2 a.m. one early one
00:23:12.560 morning that he finally figured out we do have the so-called anisotropies which is a fancy name for
00:23:18.160 this lumpiness this variation in cosmic microwave background and he was so excited he had to get
00:23:22.880 on his push bike and and ride to George Smoot's house and and and slipped the the the research
00:23:29.680 he's slipped the the discovery of the the anisotropies underneath George Smoot's door I think with
00:23:35.440 the words we found it written on the top of it and so that was the moment that was the moment of
00:23:41.040 the discovery of the cosmic microwave background anisotropies now why is this something who cares
00:23:46.320 about this well the reason that you get these anisotropies that these variations in the temperature
00:23:52.880 goes back to quantum theory. Stephen Hawking actually described it as like looking at the face of
00:23:59.040 god looking at this images like looking at the face of god to bit of an exaggeration of course but
00:24:03.600 basically the lumpiness is there in the earliest universe the the earliest image we have of the
00:24:10.080 universe that lumpiness seems to be explained by quantum mechanical laws the quantum fluctuations
00:24:15.520 acting on a universe which was small enough you know the size of an atom or whatever such at the
00:24:20.640 effects back then had lumpiness in them which quantum mechanical laws lead to this lumpiness and so
00:24:27.280 then when the universe expanded so to the lumpiness and so you get this lumpiness today on the
00:24:33.440 very larger scales because that is an image of what it was like at the beginning of time because
00:24:43.120 the beginning of time was governed by quantum mechanical laws which necessarily led to this sort
00:24:48.160 of thing if we didn't have quantum mechanical laws presumably the universe would have been
00:24:54.720 perfectly uniform and it would have expanded out such that you wouldn't get lumpiness which means
00:24:59.200 you might not have gotten stars in the way that we have stars now and so you certainly wouldn't
00:25:04.080 have had the distribution of galaxies in the way that they are now so I find that absolutely
00:25:08.640 astounding it's astounding to think that the effects of quantum theory at the very smaller scales
00:25:16.960 namely on the universe when it was much smaller than an atom can be seen today revealed today
00:25:23.760 in the universe as a whole the the structure of the universe as a whole the very largest scales
00:25:32.560 have been determined to buy what was going on at the beginning of the universe which
00:25:38.560 shouldn't be so surprising I mean this is what goes on with initial conditions and dynamical
00:25:43.040 laws after all anyway if you want to learn more about that you can look up the the history of
00:25:48.800 the cosmic microwave back and explore after that by the way there was this thing called
00:25:52.560 W map the Wilkinson microwave anisotropy probe and so they they improved the image of the of
00:25:59.520 Kobe of the cosmic microwave background and today the most recent one is the plank the plank satellite
00:26:04.960 has has again given us images of this to even greater resolution so very interesting area of science
00:26:13.360 one of these pieces of evidence explained by the theory of the Big Bang okay after that
00:26:18.880 extended self-indulgent diversion let's go back to the book and David writes
00:26:24.160 but slight though they were this variations and density is what he's talking about
00:26:28.000 but slight though they were they are of the greatest significance in any reductionist description
00:26:33.920 of reality because almost everything that we see happening around us from the distribution of stars
00:26:38.560 and galaxies in the sky to the appearance of bronze statues on planet earth is from the point of
00:26:43.920 view of fundamental physics a consequence of those variations if our reductionist
00:26:48.560 description is to cover anything more than the grossest features of the observed universe
00:26:53.040 we need a theory specifying those all important initial deviations from uniformity
00:26:58.480 let me try to restate this requirement without the reductionist bias the laws of motion
00:27:03.600 for any physical system make only conditional predictions and are therefore compatible with many
00:27:10.000 possible histories of that system this issue is independent of the limitations on predictability
00:27:15.440 that are imposed by quantum theory which i shall discuss in the next chapter for instance the
00:27:21.520 laws of motion governing a cannonball fired from a gun are compatible with many possible trajectories
00:27:27.440 one for each possible direction and elevation in which the gun could have been pointing when it
00:27:32.160 was fired and this is the figure from the fabric of reality mathematically the laws of motion
00:27:36.880 can be expressed as a set of equations called the equations of motion these have many
00:27:43.440 different solutions one describing each possible trajectory to specify which solution describes
00:27:50.000 the actual trajectory we must provide supplementary data some data about what actually happens
00:27:56.000 one way of doing that is to specify the initial state in this case the direction in which the
00:28:00.720 gun was pointing but there are other ways to for example we could just as well specify the final
00:28:05.680 state the position and direction of motion of the cannonball at the moment it lands or we could
00:28:10.720 specify the position of the highest point of the trajectory it does not matter what supplementary
00:28:15.360 data we give so long as they pick out one particular solution of the equations of motion
00:28:20.400 okay pausing there now for more on this you can see chapter two of the science of cannon
00:28:26.880 kart by kara my letter there's a deep symmetry is already said between these two books
00:28:32.240 and to understand a little bit more about this the topic is projectile motion and if you have
00:28:38.880 the trajectory of a projectile then there are unique coordinates x and y well not unique coordinates
00:28:45.920 there are specific coordinates x and y which pick out a unique trajectory for any given
00:28:52.800 projectile as you can see there with the picture that David has provided there's going to be
00:28:58.960 if you pick out in the plane that's there in fact you'll have x, y and z coordinates in that
00:29:03.920 particular three-dimensional version of it if you pick out particular x, y, z coordinates there will
00:29:10.960 be only one of those possible trajectories that will fit that x, y, z coordinate that x, y, z coordinate
00:29:20.240 is the initial conditions so to speak the supplementary data we sometimes call the initial
00:29:26.240 conditions if it's at the beginning the final conditions which is at the end or any other
00:29:31.200 condition in between so supplementary data is what you need you need a point along the
00:29:35.840 trajectory to pick out that particular trajectory as unique and different to all the other ones
00:29:41.600 that could have possibly happened but why that particular one well that's the open question
00:29:47.600 especially when applied to the whole universe and that's what David's about to get to so let's
00:29:51.360 go back to the book where he rides the combination of any such supplementary data with the laws
00:29:57.520 of motion amounts to a theory that describes everything that happens to the cannonball between
00:30:02.880 firing an impact similarly the laws of motion for physical reality as a whole would have many
00:30:08.720 solutions each corresponding to a distinct history to complete the description we should have
00:30:13.760 to specify which history is the one that has actually occurred by giving enough supplementary
00:30:19.120 data to yield one of the many solutions of the equations of motion in simple cosmological models
00:30:24.160 at least one way of giving such data to specify the initial state of the universe but alternatively
00:30:30.080 we could specify the final state or the state at any other time or we could give some information
00:30:35.200 about the initial state some about the final state and some about the states in between in general
00:30:40.320 the combination of enough supplementary data of any sort with the laws of motion would amount to
00:30:44.720 a complete description in principle of physical reality pausing there yes that's precisely right
00:30:52.320 but as we've been keen to highlight such a description would be at best a predictive kind of
00:30:59.600 description it would never actually explain much at all about what happened like for example
00:31:05.440 evolution knowledge crash and therefore increasingly from this moment onwards what actually
00:31:11.040 occurs in the universe because from this moment onwards knowledge creation will become the dominant
00:31:16.320 unfolding feature of the universe into the distant future so long as we don't go extinct and
00:31:22.080 perhaps there are other people out there whatever the case we are going to begin constructing around
00:31:28.160 us transforming physical reality around us and that is to do with the knowledge we have trying
00:31:33.680 to understand why certain things are going to happen for example the construction of cities is not
00:31:40.720 going to be explained by the simple laws of physics and supplementary data what we need of course
00:31:48.800 is an explanation in terms of peoples choices and they're wanting to create certain things and so
00:31:55.120 on and so forth okay so we've made that point throughout the beginning of infinity but here it is
00:32:01.360 in the fabric of reality back to the book and David writes for the cannonball once we have specified
00:32:08.080 say the final state it is straightforward to calculate the initial state and vice versa so there
00:32:12.880 is no practical difference between different methods of specifying the supplementary data but for
00:32:18.320 the universe most such calculations are intractable pausing there yes this is to put things mildly of
00:32:25.760 course it's intractable to try to figure out the trajectories of all the particles in the entire
00:32:35.200 universe yes given that for a single particle just pick any single particle like an electron there's
00:32:42.400 no sense in which the observables you need in order to make a precise prediction can be known
00:32:48.160 simultaneously anyway Sam Kipers who is a physicist who collaborates with David Deutsch has written
00:32:54.560 collaborated with David Deutsch on a number of papers he's written some on his own exploring
00:32:59.760 variations subtle variations to quantum theory about a related point but I won't go into the details
00:33:06.800 about that but you can see here for Sam's excellent papers they're highly technical and I
00:33:12.400 guess to be true to be honest they're not precisely related to what I'm about to mention here
00:33:17.440 but I just want to observe that on this point about a deterministic universe and I've said this
00:33:22.880 before it's true in a very basic sense okay namely stuff is indeed determined in the universe we
00:33:30.000 live in a deterministic universe things happen according to the laws of physics and it wouldn't
00:33:35.920 matter if the laws of physics mandated that any old random stuff happened that will still be determined
00:33:41.440 by laws of physics we are governed by laws of physics as it happens we're governed by
00:33:46.960 quantum mechanical laws of physics and laws of general relativity as well things happen according to
00:33:52.240 the laws of physics but this is utterly different utterly different to things being predictable
00:33:59.200 we live in a deterministic universe but not in a predictable universe I would argue
00:34:05.520 and there is predictable in practice and there's predictable in principle and I want to suggest
00:34:09.840 that neither in principle neither in practice nor in principle can we make predictions about
00:34:16.320 the universe as a whole let me give the we can't predict things in practice for the whole universe
00:34:24.400 this is the easy one in order to be able to predict in practice how the universe is going to evolve
00:34:32.400 over time with certainty of some kind that would mean to know the conditions of the universe
00:34:40.800 right now all the initial conditions of the universe which is basically the same thing
00:34:44.000 that one's not necessarily going to be easier than another presumably right now finding the
00:34:49.040 conditions right now the very single particle would be easier than finding the conditions of every
00:34:52.880 single particle in the deep dark past because we only have access to measurements right now
00:34:58.880 so can we get this perfect knowledge that we need of every single particle in order to plug in
00:35:06.960 this supplementary data into our equations of motion for all the particles in the universe
00:35:14.720 it would seem to be clearly not one would wonder by what mechanism you're going to make these
00:35:20.240 measurements of every single particle in the universe what instruments would you need to do this
00:35:26.960 what are they made out of and are these instruments themselves that do the measurements of the
00:35:31.680 particles themselves made of particles for which you need to know their conditions at any given time
00:35:40.960 we have a recursive problem don't we we'll need instruments measuring instrument when it will
00:35:45.760 lead instruments measuring particles the positions and momentum presumably of particles
00:35:51.440 but those instruments themselves are made of particles so we need to find the momentum and the
00:35:57.280 position of those particles as well in the instruments but to do that we need more instruments so
00:36:02.560 we've got this weird infinite regress of trying to measure everything including the measuring
00:36:08.960 devices themselves so I don't think that in practice it's possible and in principle we've got
00:36:16.480 a problem as well people often say things like well the oracle or the supercomputer
00:36:21.920 to take it away from the supernatural the supposed quantum supercomputer of the future
00:36:28.880 might be able to somehow or other have the conditions of all particles in the universe plugged
00:36:35.920 into it and thereby make a perfect prediction of how the universe is going to unfold off into the
00:36:42.320 infinite future but I don't think that it can and and and one reason why I don't think that it
00:36:49.440 can is because the conditions right now the the whatever the conditions are at time t call it now
00:36:58.320 in in this room where I am are going to be different to the conditions for particles on the
00:37:04.320 other side of the galaxy let alone the other side of the universe there is no now here now
00:37:10.960 that is the same for here as compared to the other side of the galaxy relativity tells us
00:37:17.440 that whatever you think is going on here right now might be well and good but your knowledge
00:37:22.560 of what is going on over there is limited by the finite speed of light you cannot know now
00:37:29.840 what is happening there now because guess what there is no simultaneous now here and now over there
00:37:37.760 that is known as the relativity of similar to nayity now I'm somewhat practiced in explaining this
00:37:43.840 so let me do it very very briefly this is that this is the classic so called thought experiment
00:37:50.960 and it goes like this let's say you're sitting in the middle of a train and it's a special kind
00:37:55.680 of train where you can pull a chain in the middle of the train and it will turn on a light that
00:38:02.160 is immediately above your head until you're left until you're right there is a door and the door
00:38:08.240 is opened at either end of the train by a light so as soon as the light when you switch it on
00:38:13.760 reaches the doors the doors will open so if you're right in the middle of the train and you pull
00:38:18.960 the chain and the light switches on then it will reach if you're right in the middle of the train
00:38:23.520 it will reach the front and the rear doors simultaneously or reach both of those doors at the
00:38:28.960 same time so both of the doors will open according to you at precise at the same time now this is
00:38:36.000 all dependent on the fact that the speed of light is constant it doesn't matter whether the
00:38:41.200 light is traveling to the left or to the right forwards or backwards to the rear door or to the front
00:38:46.800 door the speed of light is constant always for all observers that's a fact that is one of the
00:38:53.280 postulates a special relativity but now and here's the key brain bending thing if you've never
00:39:00.800 heard it before let's say you're watching from the outside of the train as someone inside the
00:39:06.960 train performs this experiment they are turning the light on there in the middle of the train they
00:39:12.400 observe the light travel to the front and rear of the train striking the front and rear doors
00:39:17.520 simultaneously causing those doors to open up simultaneously but you are now on the outside let's
00:39:24.240 presume the train is now moving from the left to the right the person inside the train they don't
00:39:30.480 care about this after all the light's still going to travel a certain distance to the front
00:39:34.720 and the certain distance to the back and that distance happens to be the same the doors open
00:39:37.840 simultaneously but for the person outside as they see the train moving from the left and moving to
00:39:43.680 the right what they notice is as the light is switched on as the light is switched on it will travel
00:39:50.000 towards the rear of the train which is coming towards the light now so effectively that light beam
00:39:56.320 has a shorter distance to travel it will strike that rear door first whereas the light beam that
00:40:03.280 is traveling towards the front door now has further to travel because that front door has moved away
00:40:09.680 from where the light began and it has further to travel so for the person outside they see the
00:40:15.520 rear door strike the beam of light causing that rear door to open up not simultaneously with the front
00:40:22.640 door because at the front door the light beam is still yet to reach there because it's a finite
00:40:28.640 speed of light it can only travel so far in so much amount of time and although it struck the
00:40:34.720 rear door opening that rear door the front door is still closed so the permanent person on the outside
00:40:39.520 of the train sees that the rear door is opened and the front door has not yet opened but the
00:40:45.200 person inside the train says no I'm here inside the train and I have seen that both of those doors
00:40:50.160 have opened simultaneously the person on the outside says no they haven't I can see right now I
00:40:55.040 have made an observation these two doors have not opened at the same time have not opened simultaneously
00:41:02.720 now if you've never heard that before it can screw with your mind a little bit I would suggest
00:41:06.880 okay this is the relativity of simultaneity and it's to do with the deep fact of the universe which
00:41:12.640 is the speed of light is constant this is not something that we are used to in day to day life
00:41:19.200 people have struggled for a long time they did struggle for a long time to accept that this is
00:41:23.680 true and physicists know that this is true and you should accept that this is true because this is
00:41:28.800 the explanation of how things work so people won't agree about now about what is happening now
00:41:36.480 for the person inside of the train they say that now the two doors open simultaneously
00:41:41.840 a person on the outside they say no now the doors didn't open simultaneously in fact there is
00:41:47.440 no now in which the doors open simultaneously in other words even for a simple situation like this
00:41:52.240 we can't agree on what the supplementary data might be okay we can't agree let alone what's
00:41:58.720 going to happen here compared to the other side of the universe for every single particle now
00:42:03.040 there's a proviso here I accept because there is something actually that can agree on that's
00:42:08.880 something is called the space time interval they will agree on what that is so there is actually
00:42:14.800 something that's constant in the universe so to speak in relativity but that's beyond the scope of
00:42:18.960 what I'm talking about right now anyways this all comes to bear on this idea that we can have
00:42:24.880 something like perfect knowledge in principle of the initial conditions of the universe now
00:42:30.960 or at any other time making what I would suggest an in principle prediction of the unfolding of
00:42:40.080 the universe despite the fact everything is determined an in principle prediction cannot be done
00:42:44.400 and because the in principle prediction cannot be done there's no point debating about what such
00:42:51.680 and such evolution of the universe would be a family we knew we can't know and it among many
00:42:58.480 other things I think this is well there's many ways but this is a this is a reason why reduction
00:43:04.240 should accept the fact they shouldn't be reductionists but one reason why they can accept the fact
00:43:10.720 that this provides scope for genuine creativity in the universe things to be able to come into
00:43:17.520 being in the universe that weren't there before that can't be adequately explained by and appeal
00:43:23.520 to the laws of physics things like knowledge creation okay so all of that was just a response to
00:43:28.400 David's sentence there where he says but for the universe most such calculations are intractable
00:43:35.840 yes intractable to put it mildly back to the book and he writes I have said that we infer the
00:43:43.600 existence of lumpiness in the initial conditions from observations of lumpiness today but that is
00:43:49.440 exceptional most of our knowledge of supplementary data of what specifically happens is in the form
00:43:55.280 of high level theories about emergent phenomena and is therefore by definition not practically
00:44:01.280 expressible in the form of statements about the initial state for example in most solutions of
00:44:07.200 the equations of motion the initial state of the universe does not have the right properties for
00:44:11.120 life to evolve from it therefore our knowledge that life has evolved is a significant piece of
00:44:16.800 the supplementary data we may never know what specifically this restriction implies about the
00:44:21.440 detailed structure of the big bang but we can draw conclusions from it directly for example the
00:44:26.560 earliest accurate estimate of the age of the earth was made on the basis of the biological theory
00:44:30.960 of evolution contradicting the best physics of the day only a reductionist prejudice could make us
00:44:36.800 feel that this was somehow a less valid form of reasoning or that in general it is more fundamental
00:44:42.800 to theorize about the initial state than about emergent features of reality even in the domain of
00:44:48.000 fundamental physics the idea that theories of the initial state contain our deepest knowledge
00:44:52.080 is a serious misconception one reason is that it logically excludes the possibility of explaining
00:44:57.360 the initial state itself why the initial state was what it was but in fact we have explanations of
00:45:03.440 many aspects of the initial state and more generally no theory of time can possibly explain it
00:45:09.360 in terms of anything earlier yet we do have deep explanations from general relativity and even more
00:45:15.680 from quantum theory of the nature of time and pausing that again see some more discussion of this
00:45:22.880 in the science of can and can't if you can't wait for my discussion of the fabric of reality chapter
00:45:29.280 11 which is not going to come for presumably months or of course hopefully buy the book by the
00:45:36.480 fabric of reality and get there much sooner back to the book David writes thus the character of
00:45:42.400 many of our descriptions predictions and explanations of reality bare no resemblance to the initial
00:45:47.040 state plus laws of motion picture that reductionism leads to there is no reason to regard high
00:45:52.000 level theories as in any way second class citizens our theories of subatomic physics and even of
00:45:58.000 quantum theory or relativity are in no way privileged relative to theories about emergent properties
00:46:04.560 none of these areas of knowledge can possibly subsume all the others each of them has logical
00:46:09.840 implications for the others but not all the implications can be stated for they are emergent
00:46:14.320 properties of the other theories domains in fact the very terms high level and low level are
00:46:20.000 misnomers the laws of biology say are high level emergent consequences of the laws of physics
00:46:25.440 but logically some of the laws of physics are then emergent consequences of the laws of biology
00:46:31.040 it could even be that between them the laws governing biological and other emergent phenomena
00:46:36.960 would entirely determine the laws of fundamental physics this this I'd reported this idea that
00:46:43.440 the laws of physics might emerge from some fundamental laws of biology I'm reminds me of that
00:46:51.520 scene in the Big Bang theory with Sheldon who's the character who's the theoretical physicist
00:46:58.160 and he's debating with who would eventually be his girlfriend Amy who's a neuroscientist I think
00:47:04.800 and they're arguing about what's more fundamental or what's logically prior the laws of physics
00:47:10.960 or the laws of neurobiology Sheldon of course says physics is but Amy has this argument
00:47:17.760 that given that all of what we know about physics comes from human brains anyway and understanding
00:47:23.520 of how they work must be a pre-orion away prior to physics if you really want to understand where
00:47:29.600 physics is coming from you've got to study the human brain therefore neuroscience is deeper
00:47:35.040 that what physics is of course that's a silly debate and it misses the point about actually
00:47:41.520 what thinking is and the fact that the physics is outside of brains and all that sort of stuff
00:47:45.840 but it made me think of that and that idea that David just says there that's quite the striking
00:47:51.760 claim that the laws of biology and other emergent phenomena might completely determine
00:47:58.880 the laws of fundamental physics would certainly upset their Sheldon Cooper's of the world or
00:48:03.760 anyone who wants to argue that the physical laws and initial conditions picture rules out the reality
00:48:10.080 the reality of emergent phenomena free will of course excuse me back to the book David writes
00:48:19.760 but in any case when two theories are logically related logic does not dictate which of them we
00:48:25.360 ought to regard as determining wholly or partly the other that depends on the explanatory
00:48:30.640 or relationships between the two theories the truly privileged theories are not the ones referring
00:48:36.080 to any particular scale of size or complexity nor the ones situated at any particular level of
00:48:41.520 the predictive hierarchy but the ones that contain the deepest explanations the fabric of reality
00:48:47.920 is not only consist of reductionist ingredients like space time and subatomic particles but also of
00:48:54.640 life thought computation and the other things to which those explanations refer what makes a theory
00:49:02.560 more fundamental and less derivative is not its closeness to the supposed predictive base of physics
00:49:08.880 but its closeness to our deepest explanatory theories quantum theory is as I have said one such
00:49:15.600 theory but the other three main strands of explanation through which we seek to understand the
00:49:20.000 fabric of reality are all high level from the point of view of quantum physics they are
00:49:26.160 the theory of evolution primarily the evolution of living organisms epistemology a theory of
00:49:32.160 knowledge and the theory of computation about computers and what they can and cannot in principle
00:49:37.360 compute pausing their my reflection so these are the four strands quantum theory theory
00:49:43.840 evolution epistemology theory of computation now as I said previously our previous episode
00:49:49.280 this idea of theory of everything well already there's unification happening here and to some extent
00:49:55.680 we must concede the theory of computation really has been subsumed into physics anyway it's a
00:50:01.840 theory of physics so it's a part of quantum physics I mean the theory of quantum computation really
00:50:06.800 is the theory of computation as viewed through the lens of quantum theory and places you know
00:50:15.120 strict constraints on what computers can and can't do namely what those quantum laws of physics
00:50:21.040 say that they can and given that brains the things that create knowledge about the universe are
00:50:27.920 a kind of computer then the theory of knowledge really is very much a part of this theory of
00:50:35.520 computation which is a part of quantum physics as well so there are these deep deep links
00:50:39.520 and I said in the Nexus videos well well given that we are involved biological organisms
00:50:46.480 with kind of we human beings we are the we are the thing the entity in the universe that
00:50:55.200 unifies all of these things in a very real physical way okay we've evolved to create knowledge
00:51:01.200 which is itself a kind of computation that is done by a computer obeying quantum laws of physics
00:51:10.320 okay so again my Nexus video for more about that okay let's go back to the book and David
00:51:17.280 writes as I shall show such deep and diverse connections have been discovered between the basic
00:51:23.280 principles of these four apparently independent subjects that it has become impossible to reach
00:51:28.240 our best understanding of any one of them without also understanding the other three the four of
00:51:33.600 them taken together former coherent explanatory structure that is so far reaching and has come
00:51:38.960 to encompass so much of our understanding of the world that in my view it may already properly
00:51:44.240 be called the first real theory of everything thus we have arrived at a significant moment in
00:51:50.080 the history of ideas the moment when our scope of understanding begins to be fully universal up to
00:51:56.400 now all our understanding has been about some aspect of reality untypical of the whole in the future
00:52:03.040 it will be about a unified conception of reality all explanations will be understood against the
00:52:08.160 backdrop of universality and every new idea will automatically tend to illuminate not just a
00:52:14.160 particular subject but to varying degrees all subjects the dividend of understanding that we will
00:52:21.120 eventually reap from this last great unification may far surpass that yielded by any previous one
00:52:28.080 for we shall see that it is not only physics that is being unified and explained here and not only
00:52:33.680 science but also potentially the far reaches of philosophy logic and mathematics ethics politics
00:52:40.400 and aesthetics perhaps everything that we currently understand and probably much that we do not
00:52:46.400 yet understand porting their my reflection if I was to reflect on why I would bother
00:52:54.160 spending so much of my time explaining these ideas why I would devote a rather large fraction
00:53:03.760 of my life to doing this to trying to do public outreach to trying to spread these ideas
00:53:10.160 to try and have people appreciate the significance of this so that they too could perhaps
00:53:18.240 contribute to solving this particular problem then it's all encapsulated there I mean how much
00:53:25.040 more grand a vision of reality do you want there have been unifications in the past electricity
00:53:33.040 and magnetism into a unified theory of electromagnetism by Faraday and Gauss and others the
00:53:39.200 unification of a standard model of particle physics the unification of space and time by Einstein
00:53:47.600 you know these unifications that have happened physics but here David is talking about how
00:53:53.120 we can have the unification of disparate theories in different subjects coming together to give
00:54:02.080 us a far deeper richer explanation of reality as a whole that will touch everything everything
00:54:11.520 everything that we know philosophy logic mathematics ethics politics aesthetics okay you mentioned
00:54:16.960 aesthetics of course in the beginning of infinity as well sharpens that up too so it's not like
00:54:22.800 this is just throw away kind of I'm I'm I'm hopes that he is that he's dreaming up here
00:54:30.000 there's actually been progress made on lots of these points between the time of writing
00:54:36.240 through the beginning of infinity and through to the science of can and can't he's under work as
00:54:41.760 I've said before quantum computation that entire field was a unification of computation and
00:54:49.760 quantum theory so it's happened what more do you want out of life you know in terms of
00:54:56.000 understanding and being able to solve problems than being able to unify all of that stuff
00:55:01.200 so I can't think of a better kind of science to really dive into them this one all other
00:55:08.720 sciences are ultimately going to be aspects of this grand theory of everything and of course the
00:55:15.120 interesting thing about this particular theory of everything is it doesn't solve all problems
00:55:19.520 it just provides a framework in which we can come to understand solutions to those problems better
00:55:24.800 and of course better and so as as as he said elsewhere it would this would only be the
00:55:31.040 first such theory of everything giving us a vision there to see the next theory of everything
00:55:37.680 which would unify even more presumably once we have this this kind of theory of everything
00:55:42.880 we would then it would reveal new problems because for any solution any theory will open up new
00:55:49.680 problems that we could not possibly have imagined before in the world view that we presently
00:55:56.960 hold and so that would enable new better solutions to rise to the new better problems that we
00:56:01.920 discover let's go back to the last very last part of the book and now I'll read a little bit of
00:56:06.960 the glossary that that it's a that the end that is at the end of this book as well David writes
00:56:12.480 quote what conclusion then would I address to my younger self who rejected the proposition that
00:56:18.560 the growth of knowledge was making the world ever less comprehensible I would agree with him
00:56:23.760 though I now think that the important issue is not really whether what our particular species
00:56:30.080 understands can be understood by one of its members it is whether the fabric of reality itself is
00:56:36.240 truly unified and comprehensible there is every reason to believe that it is as a child I merely
00:56:44.240 knew this now I can explain it end of the chapter okay and that there's terminology at the end
00:56:52.080 there's a little glossary at the end and I won't always read this but I just think that
00:56:55.920 there's some stuff here that is worth going over I'm not going to read all the words in the
00:57:01.520 terminology section in the little glossary at the end of the chapter but this is worth pointing out
00:57:07.760 at the end of the chapter he's got a definition of the word explanation and in brackets he says
00:57:14.000 roughly a statement about the nature of things and the reasons for things so there you see
00:57:19.760 and as I asked David in my questions for David one of my recent questions for David and you can
00:57:24.480 find these on YouTube or on podcast I might even put a link I hopefully I remember I'll put a
00:57:29.760 link below this video to this particular one asking David about you know sort of the the
00:57:35.760 motivation for sharpening up this understanding of what an explanation is in the beginning of
00:57:41.520 infinity in the fact these TED talk you know he says that explanations are hard to vary
00:57:47.200 while still accounting for the thing they purport to account for the phenomena they purport to
00:57:51.360 account for but here we don't have that and the reason that we don't have it here is because
00:57:57.120 he thought and he says of himself you know erroneously he thought that it was just an
00:58:01.520 uncontroversial kind of a word but it's not of course we now know that and so he is sharpened it up
00:58:06.560 very healthfully for the rest of us and I think that this really pushes a popular in epistemology
00:58:12.880 ahead you know in a very valuable way because explanations reach beyond science into every other
00:58:22.400 field that we happen to be interested in and it also sharpens up what science is about science isn't
00:58:28.000 merely about testable theories or even testable explanations it's about finding good explanations of
00:58:35.120 things good explanations of things as defined in the fabric of reality go to there go there for
00:58:41.280 that now the next word he defines is instrumentalism and it's a word that comes up here in the
00:58:46.240 beginning of infinity elsewhere and it's going to come up throughout the fabric of reality especially
00:58:50.320 as we talk about the physics sections instrumentalism means the view that the purpose of a
00:58:56.640 scientific theory to predict the outcomes of experiments now that definition is only you know the
00:59:04.400 only point of that definition it seems to me it only applies to physics and even then usually only
00:59:09.680 to particular kinds of physics particle physics and quantum physics and stuff you know it's a bias
00:59:16.960 from those areas you ask a geophysicist if the purpose of science is to predict the outcomes
00:59:24.880 of experiments and they're not going to be happy with that okay a geophysicist actually wants
00:59:30.240 to know what really is in the center of the earth or in the ground beneath their feet
00:59:35.680 they want to know that that's where the minerals are okay it's not merely predicting that
00:59:43.680 the resistivity found by a particular meter that you're using to look into the ground happens to
00:59:49.120 be this or that that's not what it's about certainly not what an astronomer wants to know either
00:59:54.000 okay astronomer wants to know if there really is a planet orbiting that star
00:59:58.880 or if that star is a white dwarf as opposed to a red giant and so on much less biology
1:00:07.120 medicine think of any science that you're interested in okay instrumentalism is this
1:00:13.760 weed kind of philosophy that some philosophers are interested in and they're only interested in it
1:00:19.440 because there's this bad turn in theoretical physics quantum physics and so on okay
1:00:27.200 the next definition yeah positivism is the next word positivism David says an extreme form of
1:00:34.400 instrumentalism which holds at all statements other than those describing or predicting observations
1:00:39.360 are meaningless this view is itself meaningless according to the time criterion yes precisely
1:00:45.280 okay so positivism just rules out understanding the world at all really I mean
1:00:51.680 describing or predicting observations I mean all of philosophy mathematics is not about observations
1:01:00.000 you know pure mathematics is not about observations but it's very useful there's lots of
1:01:03.440 things that aren't about observations and anyway all statements I mean what about fiction
1:01:11.280 what about art I mean what is a positivist supposed to and this is where Wittgenstein
1:01:16.400 you know it's called the two versions of Wittgenstein you know we blame Wittgenstein for a
1:01:22.480 lot of this right Ludwig Wittgenstein in his tractatus his first book this impenetrable kind
1:01:30.880 of it's not nonsense but but basically he was trying to say that the purpose of language is
1:01:37.360 simply to describe stuff okay and if you if you can't describe stuff then well it's pointless
1:01:46.000 useless metaphysical baggage and you can you can do away with it but you know in his latter life you
1:01:52.560 know that the second Wittgenstein Wittgenstein version two I think his book was philosophical
1:01:57.760 investigations he rejects what he did in the tractatus he said as well I was wrong about all that
1:02:04.560 because he recognizes a whole lot of other reasons that language has for existing asking people
1:02:11.040 questions comforting people writing fiction and so on doing art and there's all these other
1:02:18.960 functions of language that aren't just about describing stuff or stating facts there are other
1:02:25.280 purposes for language how this escaped him the first time around I don't know but he was focused
1:02:29.440 very very narrowly very narrowly on science and problems within science and trying to be a hard
1:02:37.280 knows macho kind of philosopher who just wanted to get rid of the supernatural fair enough
1:02:44.800 or discussions of of mystical stuff fair enough to some extent fair enough okay I can understand
1:02:52.000 the motivation even if I don't agree with it but sometimes people go too far as I like to say
1:02:58.880 baby in the bathwater and all that you know you you want to try and sharpen up things in philosophy
1:03:04.400 but that doesn't mean you just do away with everything just because you've managed to dissect
1:03:12.480 out certain amounts of nonsense okay okay next word David defines I'm missing a few of them but
1:03:19.600 he also defines emergence and he says an emergent phenomena is one such as life thought or
1:03:25.600 computation about which there are comprehensible facts or explanations that are not simply
1:03:30.880 deducible from lower level theories but which may be explicable or predictable by higher level
1:03:36.560 theories referring directly to that phenomenon okay so yeah so emergence is a key part of
1:03:44.880 understanding the world you need to appreciate that and and common sense realism is about this
1:03:51.760 right man on the street type thinking is of course of course these things really exist okay and
1:03:58.720 this is why people make fun of philosophers you know they they knock on a table and they go you
1:04:04.160 know is this real kind of thing this is real and they have long debates about whether or not the
1:04:07.840 table is real man on the street looks at that and goes yeah that's ridiculous okay it's like
1:04:14.800 small brain big brain you know a galaxy brain kind of thing you know small brain is you know
1:04:20.080 like the table is real and then supposedly the big brain philosopher comes along and says well
1:04:26.000 actually the table is not real because all that's there are fundamental particles and the
1:04:30.720 fundamental particles are only things that really truly exist the table doesn't exist who
1:04:36.880 of course galaxy brain then looks at that and goes well that's ridiculous you know all you're
1:04:40.720 doing is kind of thinking in the abstract now you're not really connecting with how objects
1:04:48.080 actually do exist in reality cats exist my cat happens to be sitting here today
1:04:52.880 coffee mugs exist you know these emergent things exist people exist and in fact some of these things
1:05:00.400 that are emergent things are also fundamental things kind of fundamental thing is a thing which
1:05:05.360 features and the explanations of lots of other things as well I like to say people are
1:05:10.160 fundamental as fundamental as fundamental particles are and one day we might consider them in a
1:05:15.680 sense more fundamental than fundamental particles because people might be able to exist in a universe
1:05:20.640 without particles okay we might be able to be instantiated in something other than particles
1:05:27.920 I don't know how right now you know some sort of gravitational pattern spacetime or something
1:05:33.840 I don't know but in order to have a person you just need a way of processing information anyway
1:05:40.000 people people are this confluence of as I've already said and emphasized the theory of evolution
1:05:46.560 the theory of computation quantum theory and epistemology and so we're fundamental because we appear
1:05:53.120 in a sense across all of those it well we're not really there in quantum physics but we're
1:05:59.680 certainly there in epistemology it doesn't epistemology doesn't make sense in a world in which you
1:06:04.080 don't have knowledge creators in so far as you got evolutionary universe and there is a possibility
1:06:09.760 of people arising in such a universe and if you got people in such a universe then you've got
1:06:15.120 these things that are computers of a client in fact you just need animals for that okay I'm starting
1:06:22.080 to rant and so let me stop here for today next time we move on to chapter two shadows which is
1:06:31.040 as I have said before probably the chapter that most affected me when I first read the fabric of
1:06:38.560 reality back in 1997 because it was the chapter that cured me of my up until then
1:06:49.040 complete disillusionment with quantum physics I'd been doing quantum physics at university I
1:06:54.880 didn't understand what was going on you know I sort of I could do the problems but it was like
1:07:00.080 what am I doing I don't get it it doesn't make any sense to me this is all nonsense and I was
1:07:05.200 I was reassured by lecturers that well yeah it's supposed to be nonsense it's just a bit we just
1:07:12.080 shut up and calculate so to speak and I'd read lots of popular science books and none of them
1:07:17.280 really helped they all made it sound mystical until shadows until I read the fabric of reality
1:07:23.920 chapter two so that's next time look forward to that it's going I would presume to be
1:07:30.400 I think I'll get through it fairly quickly the reason is because I've talked about the
1:07:38.000 multiverse before I've got a five or six-part series up there on YouTube all about the multiverse
1:07:44.800 and so I'm going to be referring to that quite a bit so we'll be doing a a slimmed down version
1:07:51.520 of chapter two of the fabric of reality shadows but until then bye-bye