Chiara Marletto: Constructor Theory

okay so Carol we're here to talk about constructor theory which is an idea you've been working on with David Deutsch and I guess the first thing to say is that it's huge really in terms of its scope in its ambition it's a whole new mode or explanation in science you say and it goes deeper than quantum mechanics and general relativity and promises to solve all kinds of problems and inconsistencies in the scientific worldview in physics but in biology as well but let's just start with the basics if we can what what is this idea what is contracted theory right so um as you said constructor theory is in the first place is a new mode of explaining physics and with physical reality so there are different ways of approaching description of physical reality and actually if you look at the various levels fields that appear currently in the whole physics they all look very different from one another but in fact they have a unifying trait which is that they describe the world in terms of predictions given laws of motion and initial conditions and so the basic assumption that fundamental physics has been making so far is that that's the best way in which we can explain the world and so in fact that you know it has been quite successful I mean it with it produced a lot of deep theories as ones that you mentioned or physics so far yes bananas mold exactly so constructor theory is proposing a different way of explaining the world and if you think about it there's nothing that says a priori what is a good way of explaining the world we have a good one which is the initial conditions plus laws of motion mode which is the prevailing conception of fundamental physics and then construct the theories and alternative and why you know do we need an alternative well and that's because the prevailing conception although as I said it's been quite successful can't handle certain problems and cannot capture adequately certain phenomena that we we see in the world information is one features of life is another etc and and construct the theory takes a different mode explanation to explain those things and bring them into fundamental physics the basics are that everything is expressed in terms of statements about what transformations physical transformations that we call tasks are possible what are impossible and and why and the picture in terms of initial conditions should be recovered sometimes in approximations sometimes exactly from these statements and and so this mode of explaining which actually has pictures in physics such as for instance in thermodynamics where we say something like a facial motion machine of the first or second kind is impossible is extended to cover the whole physics and the difference from thermodynamics is that as as it is now currently current some analysis and considered as a sort of scale dependent macroscopic theory which is not really fundamental yes whereas constructor theory is about formulating exact statements about reality which are not approximate okay okay well there's a few things that I want to pick up on and the first is that if you're dividing the physical universe into tasks that are possible and impossible and explaining why how do you explain why if not with the traditional mode of laws of motion I think it's good to pick an example just explain what that means so for example in quantum mechanics there's a fundamental trait of the dynamical laws that is to say that it's impossible to clone two coppy perfectly certain sets of attributes of a physical system like in classical physics we are accustomed to think that to thinking that if you have a system a physical system with a set of attributes or States and you want to have a machine that copied those days in principle if those are this crease you can always achieve this with arbitrarily high accuracy a defining property of quantum physics is that there are sets of states of a quantum system for which that machine can be built and this statement have just given you is not formulating in terms of amical laws it's a fundamental statement about what's transformations are possible or impossible in fact ok on a set of attributes of physical system and then you may say well given this constraint we can possibly think of a settle dynamical laws that would comply to such constraint and quantum theory we know is among the set of laws but an ad other ones and so as you see we shift the logic from from the user conception where we started with you know unitary dynamics of quantum theory and then we notice that it forbids this particular operation to this other way of thinking about it we state what tasks are impossible and then we can see that certain chemicals are compatible in certain chemicals and ok so how do you recover dynamical laws because you know they're immensely valuable right we sometimes we do really want to know what the state of the universe will be at time T we do want to make a prediction so how do you get back to that from a contractor theoretic foundation yeah so the recovering of the dynamical laws is is part of future research so it's it's a it's going to follow certain logic which I can describe to you but is yet to be worked out ok and so there are two kinds of objects in the preventing conception there are fundamental to make predictions while you are there are laws and the other our initial conditions and let me just say as said as a digression that the there's a big problem about initial conditions in the preventing conception so there are no good theories of what initial conditions we had the start and the birth of the universe yeah exactly I mean there are theories around but we small just have a problem with that and in fact this is precisely brought about by the by insisting on this mode of explanation yeah and so one nice outcome of constructor theory if it works as expected is that we may be able to work around this problem and also note that in the preventing conception this is sort of inconsistency within the preventing conception if you really take the view that dynamic laws and initial conditions are the fundamental things then you either think that this should be no explanation for why you choose a particular kind of initial condition or you've got to get out of this set of fundamental tools to explain the initial conditions because you can't explain them in terms of their uncle laws because you would be having a sort of infinite regress problem so I'm just saying that the the something the prevailing conception that has to be resolved if not in terms of constructors here in terms of something else okay but going back to how the recovery might be going as I said so the constructor theory will give the statement of possible impossible tasks in terms of principles which as you said of thought are things that are supposed to underlie laws such as general relativity hopefully and we know quantum theory a bit like the principle conservation of energy does for us currently and from those statements there'll be certain that other laws which are compatible with with with the set of given constraints and also set of initial conditions so for instance certain initial conditions we know will permit things like information media what we call infrastructures your information we get to to arise to exist certain others not and that will be actually an explanation for choosing a particular set of initial conditions as opposed to another and I can't tell yet whether whether this recovery will be approximate or not but in if the theory works as expected it should cover the prediction that we currently make by the brainy inception but also adds new predictions which are not coming from venerables and each of the nations but from these other principles okay okay um can you tell me about that the concept of a constructor in itself yeah constructor of construction theory yes and that's quite important because construct a theory despite its name is not a theory about constructors okay in fact as I said the main objects are the tasks which are these physical transformations the specification of a physical transformation and so the latter abuse of these parts are possible impossible so attack can be either possible or impossible and the concept of constructor comes in with the possible possibility to concept so if there's a low physics that forbids a task from being performed to arbitrarily high accuracy then the task is impossible otherwise we say it's possible and that means that one can bring about approximations to a certain machine which is a constructor that can perform that task to arbitrary high accuracy so a constructor is really an object which represents a limit of a sequence of actual objects each of which can perform the task in question to a certain accuracy okay and if the task is possible then there is no limitation to how highly accuracy in this sequence can can be but doesn't since we know that the laws of physics are what they are there's no perfect constructor occurring in reality so constructor has a particular property the ideal one that causes the transformation and retains the capability of performing it again so as a crucial feature which seems out constructors from other things that may accidentally cause a transformation but don't have giving it you're retaining the property of causing it again okay so if you think of a heat engine for instance that's an instance of a constructor because it performs a certain task and after that it's still in a deal case capable of performing it again and again okay if the task is possible there's no limitation to how well you can approximate this behavior in in reality all right and for soap so one possible objection I had was that the appeal of constructed here is that you can make the exact statements by areas like thermodynamics and information and life but given that the theory contains this idea of a constructor which is only ever approximate are you just sort of shifting the approximate nature of those areas into another part of your framework that's a very good question because the know so it's important to understand what's exact is the statement that the task is possible so the statement that there is no limitation to how well you can perform the task and that's an exact statement the way in which you think of of that statement is as permitting a sequence of ever-improving objects which can approximately do the behavior of a constructor but the exactness stays in in the statement that there can be such a sequence and that statement as I said is exactly the sense that does involve complex Nations ensembles scale dependent notions or are the kinds of approximate statements okay and so if we say the task as possible it applies at all scales and to all there is okay unlike what happens say to the second law of thermodynamics as it is currently formulated where as we know that statement only holds as a certain Cael which is never actually specified because we know that say it provides two heat engines Victorian ones but we don't know whether it may or may not apply to an engine which is just make a few particles and scan normal engine okay and that's a problem in the current formulation of thermodynamics constructor theory actually has a way of formulating phenomics in such a way that it is exact right in these terms so it's a very important question so the constructor is really a helpful tool that we may have in mind just to understand what possible means okay but it isn't fundamental in the theory what is fundamental is the statement that can exist such sequence of ever-improving approximation school to to a constructor which means that the task is possible okay so I'm sure this has some radical implications for reductionism and ideas about levels of reality or they just seem to be thrown into the air by this kind of way of thinking yeah I know why sure I think biting myself here but yeah well in the first place it says that reductionism made sense within the prevailing conception so if this new way of explaining reality works out that means that reductionism for those who are kind of keen on it should be at least reviewed and updated so there may be a new way of talking about reductionism within a constructor static picture I don't know and on the other hand it also says that what reductionism in the prevailing conception used to regard as emergent entities precisely objects on which tasks can be performed macroscopic ones for instance will be fundamental elements in the constructor theoretic picture and yet you can provide exact statements about those so you know productions picture if you think of a computer performing computation such as a not operation on some input the only fundamental level really is that everything is reducible to the movement of the electrons within the computer given the initial conditions and so if you ask whether a transistor is why the transistor is off at certain point the only fundamental answer is because the initial conditions of the electrons were such-and-such initial conditions and that's why the transistor is off yes whereas I statements such as the reason why it's off is because the computer is actually factoring number and the input number was 15 and the off transistor codes for one of the output three or five isn't regarded as fundamental at all whereas in constructor theory we can actually make of that level of explanation one about computation being performed etc and level at which we can formulate exact statements which is due to the fact that we switch to a different mode of explanation so I think the lesson here is what counts as an emergent entity depends on the mode of explanation that you choose and therefore what was regarded as emergent in the preventing conception doesn't he's not emergent and is not approximately in constructor theory and by switching to construct a theory we hope to be able to formulate exact laws about those entities that we regarded as emergent in the providing conception yeah it's very interesting it does boggle my previous way of putting all this stuff together in a pleasing way you know i revoke you know i remind again stickers I think now can't be racks I'm so used to thinking like this yeah it's mine bending in a way well in a way the whole history of physics has been to go beyond boundaries in fact when physics was born it was you know going out of certain up certain practice which actually were magical practice in the first place and what physics added on top of those was a complete freedom of questioning reality and understanding it so like there were no dogmas there wasn't there were no pre assumed truths that you couldn't actually question which is what you are what in instead you doing because the magical practice is always something that you can't question which is you know the magical words or something and and then somehow this preventing conception implicit assumption has kind of narrowed down the original altitude of physics because instead of aiming at formulating laws about realities to solve problems that may occur one you know in our understanding of it a full stop it also said well we must do it in a certain particular way which is this one that has been so successful so far there by mmm adding a rule which on face of it is is just arbitrary and it's probably you know it's come up because we haven't seen it things have been so successful so far if formulating that in those terms you know I think it's not a good enough motivation so if you could find a different way of explaining reality which is effective in certain areas then we should go for it okay so my experience is trying to get to grips with constructor theory it's that it's quite easy to grasp this contrast between the physics of what happens and the physics of what could happen or could possibly happen but what's harder is to grasp why we need to make this big conceptual leap so I've made a list here of six motivations for construction theory in surprise I've been able to identify them so you think Larry goes out you can just give me a quick yes no or maybe it's whether yeah these are the other problems you're addressing okay so one they need to provide a foundation for physics which underlies our predictive theories and tells us what the world is really like yes okay yes that's good to the need to incorporate the concept of information in fundamental physics yes okay three the desire to subsume existing physics within a broader quantum computational framework a I would say yes and no it depends on what you mean by this so maybe we'll go back yes yes well couple cavities yeah okay good so doesn't maybe for the need to accommodate the concept of possibility and hence causation and maybe even free well in physics yes okay five the need to explain the capacity of so-called constructors like biological cells to perform highly accurate physical transformations in a way that the prevailing perception of physics doesn't really seem to allow yes well the point is understanding what the existence the possibility for those things to arise well does that tell us about the underlying physics America which is the question that it's hard to handle in the providing exceptions okay okay welcome back that as well and finally six the desire to promote kind of optimism about what is possible with knowledge and technology yeah well I guess that's not I would say it isn't a motivation it's an upshot and of the same species as the other okay motivations because the other ones are something of the form the existence frame a dozen is lacking in certain respects and we would like to improve on that record whereas in in in this particular from this particular worldview that constructor theory provides one can in fact have a quite broad philosophical implications for how we look at the world and how life and and also knowledge creating systems such as humans regard themselves in the big scheme of things and I don't so that's kind of an aim of theory really it's not a career motivation all right well I start with this business about foundations for physics sir can you tell me what a foundation is and why we would want one well in any physical explanation there are some primitive elements and those we regard as foundations for the particular theory in question and I think that the because of the way knowledge grows etc there isn't an ultimate foundation in fact anything that we may regard this primitive within a certain theory for example atoms may turn out later on to be not the prematurity and to be explainable in terms of more fundamental entities right and so there's in fact into any room for such improvements and interact-as's as we tentatively improve on our understanding of reality we go deeper and deeper and we have more layers of such explanations some titles all the way down sorry yeah yeah wait except that and each step of refinement of understanding you're not trying to chase some ultimate foundation for everything as I said every time you find a new problem it may turn out that you need to think of a deeper layer and that's good then the incremental difference between what you knew before and what we're not knowing at the end is a tentative kind of progress towards understanding reality okay so taking this view however it makes sense to think of what given you know if you take a particular theory or particular way of formulating laws of physics walk you regardless fundamental entities in that particular theory and in the case of providing construction as we said they are that I'm closing the initial conditions and in a case of constructor theory they are these principles that are expressed in terms of posture impossible tasks right now the reason why these kind of foundations are more telling about reality than than the ones that bring section assumes is that they were in the first place the principles of construct theory are not theory dependent so they are more general in that they are designed to underlie even future theories that we may come up with so for example they have the same status as a principle conservation of energy and that principle is a an entity which we regardless you know guiding our guessing towards for fusion theories that may improve on quantum mechanics and general relativity right so when you read and go to new foundations is that these principles are more general then then current radical theories that we have and hence may prove useful for quantum gravity problems for instance ok and the other thing is that with respect to existing principles pressure principles or dynamics for example they are because of the screeching to a new model explanation they accommodate more physical reality so for instance we have principles about information which aren't hand-waving statements about what you know information may be like in a approximate picture but there are exact statements about what transformations you can perform on a physical system of the same kind as the statement about the impossibility of cloning states in quantum theory that I mentioned before so the need for new foundations is precisely due to the fact there are entities phenomena which are either imperfectly accommodated currently such as Thurman article laws and things like information or they are not accommodated at all in the parenting conception such as you know questions about what does the existence of what does the possibility of natural selection tell us about the laws of physics and the fine-tuning question and so on ok I mean I find what you're saying about um structure theory being foundational because it's a theory of principles really interesting but I think a lot of people would have worries about the fact that principles in themselves aren't testable and isn't science supposed to be about what is Festival ah yes so I think it's a misconceived way of looking at principles so this is actually a huge topic in in the positive of wealth of knowledge of epistemology so the way which principles are tested is that so principles are laws of our laws and so what one does is that usually tests laws that conform to those principles so there isn't really a new conceptual principle in constructor Theory it's just that the ways in which principles are formulated is different because we use this new mode of explanation but the logic of destiny is really the same as you would go about to pass the principle of conscription or energy ok so um the principle conservation of energy is that energy is never created or destroyed so if you find some strange phenomena which seems to be getting energy from nowhere or to losing energy then that encourages you to invent a theory explain why and then you test that theory yes so in the analog of constructor theory what are your principles on what theories might I suggest which are then testable ok so I can bring up two examples okay one is an example of a new principle that didn't exist before and this is the interoperability principle for information which can be expressed in very elegant and exact terms and construct a theory but really expresses a thing that can be explained by what you're already observe in physical reality that is to say that if we have two systems that seem to be capable of instantiating information for instance the lights of a traffic light actually the lamps of the traffic light that could you know green and bright for example and then we will bring we have another system such as a bit you know a transistor that my encoder bit of information okay so those two are a transistor and the traffic light are in fact two information media and the reason why they are so is that they you can perform certain transformations on each one of them so for instance the traffic light can be transformed in such a way that the green light goes to a red light so you could switch from green to red that allows you to signal something and also you can if you have another traffic light you could copy the information from the first traffic light to the second one by say having you know if you have a red light on the first one you could set up a particular system or switch so that the red light would be copied and appear on the other traffic light okay at the same time so there'll be a correlation red red okay and likewise for the green light so there's a copy of a little property from each traffic light to another one okay and there's also this swap ability property of the states so a green can go to red and red can go to green okay now all those things are tasks and we are saying that the information media such as traffic light are things that can that on which you can perform certain transformations and certain tasks the thing that we observe in the in our world which is quite remarkable is that whenever you have two such systems traffic lights and transistor for instance you can always copy the information from one to the other so the zones there is always a way of copying information not only from a traffic light to another traffic light but really from a traffic light to any other object which has these properties of swap ability and copy ability okay so that's what allows the information to be transformed in you know from from one substrate to another and this copy ability property is what the interoperability principle expresses and so it says that whenever you have two systems that separately qualifies information media if you take the composite system you still have an information medium which means that you can have certain tasks performed on the whole that can be interpreted as copying information from one to the other and this really applies to anything and that principle would for instance rule out theories which suppose that there exists a say dark sector of the universe that can only weekly interact with the other sector because the combined system of an information may give me in the dark sector and information medium in yellow sector wooden wouldn't have this property of being of allow information to be copied from one to the other okay so that already has you walk what these principles rules out but it may also say that in a certain context you know in certain sort of macroscopic scenario one needs to postulate the existence of an additional particle for that to be you know for this principle to be satisfied so this is really what they like the principle conservation of energy so it's it's similar in logic but it it's really new and it was impossible to feminity before exactly because you had to say something viable tasks are possible and system so that's one example the other kind of principles are improvements on current principles that were reading approximately knew for instance the Thurman AMEX principles so as I said before the second law of thermodynamics in the pending clouds use formulation that is to say the one about heat engines which forbids the existence of a professional machine of the second kind is at best regarded as the macroscopic as taking about microscopic systems that is nothing to do with fundamental physics it's very helpful it's you know it has driven the Industrial Revolution so it's been extremely powerful but if you then shift your focus from large heat engines to engines that are at the nano scale and of course we we can now do so it's unclear what the law really says because it only applies in what is called autonomy limits so for for a large number of subsystems where large is never actually specified so the law is vague and it isn't exact now most physicists would say that that's the reason why it's vague is that it isn't a fundamental law and so that's the end of the story and if you just had a an engine that had one particle as a working fluid you wouldn't expect the second or perhaps to hold now in contracted here you can formulate the second law in exact terms and so which means that you would be able to formulate a scale independent version of it which could help in this sort of scenario to make new predictions about such devices okay so even though we haven't yet produce any such prediction the principle has been formulated so you know imminent future work maybe would be to try and see what this implies for those for those systems just to pick up on this idea about making information fundamental is for any for Qi when saying that maybe it just isn't you know I said the counter example I have in my mind is that you know if I was to hide a bit of paper in the bit of paper had said smile or something like that and he smiles then clearly some information has been transmitted but if we were to describe you and me and a bit of paper and the smile add a kind of quantum mechanical level we just wouldn't see you or me or the paper of the smile we would just see a wavefunction so is already yeah it's really much this idea that information isn't fundamental and only comes into play at a certain level of approximation really tomorrow so question one should understand a bit more what we mean by information is fundamental because yes persons a bit of a buzz word or something but but what we actually mean is just that when we use this word information and we describe it's not just like the ones that you've just described what we really mean is that there are certain regularities the laws of physics yes and such regularities ah mmm instantiated in quantum mechanics because one's mechanics obeys the two principles that I just mentioned before but you can't distill them you can read them in quantum mechanics only because well mechanics as you said is only about you know predicting what the wave function that describes various parts of that paper will do when put into in interaction with staff in my brain and etc but what it misses is that there is an additional regularity hmm that is about the fact that as I said if you haven't an information medium such as a piece of paper and an information medium such as my brain and you consider the composite is not them then no matter what the actual dynamical model you're using is you expect that there will be an interaction allowed so that the transfer of the signal that you were talking about your will be possible and this particular statement is theory independent so it doesn't refer to Punk mechanics unitary evolution trainer equations etc and therefore it applies to converse here that perhaps creates a successor as well and will help us to pass you know know what to look at when we're searching for a better theory than Condor theory okay so that's the added value of the other principle okay I guess it relates to this idea that you are radically rethinking idea ideas about levels of reality yes so I guess my question is motivated by the thought that the quantum mechanical level is somehow primary and you're resisting that well I'm resisting it because it doesn't explain it doesn't help solving the problem and what is it about the laws of physics that makes us a capable of setting up that sort of signalling system yes because on the face of it if you just take unit resolution and initial conditions you will see a nice unit relieve Olding universe and you we'll be able to say what happens to subsystems but nothing that helps you understanding what is that added regularity that you can express by by the constructor theoretic picture yes and I'm interested in addressing unsolved problems and whenever I see that something is done is insufficient then I I am very eager and happy to get on with something that works and I think it would be very unsatisfactory to leave and explained why this signaling process works okay so that's what constructed theory does with the principles that are in the Constructors here information okay so I gather that construction Theory got started in this area of quantum computation which tapered which burst and I'm a total novice here so I just wonder if you could give me just the broadest brush account of what quantum competition is and how it initially gave rise to doctor theory right so so quantum computing is a branch of and has turned into a branch of fundamental physics really and it does it comes from the idea that computers are really physical objects which means that they walked the computational tasks they are capable of performing really depends on the laws of physics that the elementary components having the information obey so the there is a classical Turing machine which is based on a discretized version of classical physics now the question is what happens if instead of having the elementary components obeying those laws you take as a metric components things like an electron spin which weighs quantum mechanics instead of classical physics so the answer is quite surprising and it's beautiful you can still think of you can still define a thirty-day standard under quantum mechanics a universal computer which is the universal quantum computer which is what everyone is trying to realize currently in actual vs. and this computer has access to a range of algorithms so ways of performing computational tasks which is wider than one that classical computers can access and which means that we can program a quantum computer to perform certain computational tasks in a more efficient and more powerful way and there are certain algorithms then can only run on the universe on the quantum computer and count on a classical computer so that's kind of idea and the whole enterprise of quantum computing is to do with designing new algorithms and understanding certain applications of this scheme which is so they applied part for example quantum cryptography which supersedes the classical way of encrypting information and then there's the more foundational side which is understanding what quantum computing tells us about reality so for instance this idea that you can define an object like which is a universal computer that is capable of performing all computational tasks that are possible under the laws of physics is a very interesting property of a law of physics and it is it is something that our laws of physics seem to have and it's interesting to understand what that means about them so if you go along that side apart from you know casting very interesting very interesting light on the foundations of quantum physics which is a whole research area so I'm sending what kind of computing tells us about quantum physics itself which is we know is quite controversial ok what kind of it means so apart from that you can also investigate whether there's more to you know there's no general entity than a universal quantum computer that you might think of and this is what needs us to construct the sphere in a way which is good notion of universal constructor so this was something that phenomen investigated in a toy model which was defined in kind of cellular automata carnet sort of context but the idea is very general and again it's where the universal constructor is an object which just like the universal computer has the capability of performing all paths that are physically possible and the existence or non-existence of such an object again is very interesting property of the laws of physics because you may have a number of tasks possible but it may be the case that you only have specialized constructors for each one of them and you may not be able to integrate all of them into one object which is the universal constructor that when program in the requisite way will be able to perform each one of those tasks and so the contoso constructor generalizes to general constructions what the university computer does in terms of computational tasks so the idea that powered constructor theory at the start was well quantum computing isn't the whole of physics because we talk about information processing tasks only is it possible to formulate them you know the whole physics in terms of possible impossible not computational tasks but tasks so computational tasks are really tasks transformations on information media a generic task need not be your new information medium so constructed Theory deals with generic tasks things like you know a refrigerator operates on on some estates and some estates are not technically 'king they are not they don't constitute an information variable so then because they're not distinguishable perfectly so those kind of tasks are not really computational tasks in the strict sense but they they see there are meaningful tasks and so the idea was to generalize this logic of quantum computing to the whole physics but then it allowed the quantum that constructed here was much more than that and this is what we have been discussing it's taken a life of its own yeah exactly okay oh yes all right what turning towards some slightly more kind of human implications of these ideas like I've heard David Deutsch say that constructor theory will find a place for well first of all possibility but as a result concepts like freewill and causality in fundamental physics in a way that the prevailing perception doesn't and the idea there is that because in the prevailing perception things like that happen or they don't and there's no room for the idea that something could happen and freewill is about whether I could choose rice and set of chips or causality is about whether a fire could burn down a forest or something like that those concepts look full-on in the vedic conception but how does constructor Theory remedy that yeah so I think the issue of causation is slightly separate from the issue of clashes quite separate from usual free will but there can related by common problem in the preventing conception so I'll just take one at a time so the causation issue is just that in the as we know in the pairing conception you have fun lines description which is in terms of this really sequence of events that a universe may go through as the laws of dynamics unfold even the develop proper conditions at the boundary really if we won't talk about space-time and there already you have a problem because it's arbitrary whether you know you choose the initial conditions and then you let the universe evolved or you choose the final conditions and that you at the universe go backwards right divergent Russell's worry about yeah it's exactly so so there is only sequence of events but it's meaningless to say that something that's called something that comes after why just choose another action yes precisely because you could involve everything and you would have a physically meaningful picture but different causes so notion people yes the idea of that the present or the future cause in the past is not our idea of course actions yes precisely and that doesn't seem to be a way of calm making a more fundamental idea notional causation as we informally conceive of it in constructor theory vice versa the notional causation is handled by this idea of having a subsystem of the universe that behaves approximately as a constructor so a constructor when presented with the substrate in its input States for instance refrigerator when presented with the right input glass of water temperature and certain energy resources is capable of sending that object that glass to another state where the temperature is lower and by depleting some energy in doing so and the thing that makes the constructor a cause for that is that in doing so it stays the same so the possibility of having arbitrarily accurate approximations to this entity that when coupled to another system performs a sudden transformation and stays the same is the way in which we think about courses in constructor theory so the cause is you know a constructor a constructor so that by when we say it is possible we also mean that the transition between the end point and the starting point can be caused now the way in which disconnected with freewheel goes in steps and one has to bring into the play the notion of knowledge so once will you have a handle on information meaning Pataca systems that obey the principles of constructive information and have certain tasks possible in them so once you have defined that class of objects then you have a handle of information and then you can worry about special kinds of information that we all know you facing our world such as valuable information the kind of information can cause itself to rain instantiate it in physical systems for example for example but the the DNA that is called the codes for a particular adaptation that is helpful in certain environment is a particular kind of information that's different from the from from a random sequence of bases which is causing itself to remain unshaken physical systems because it's causing self to be replicated and it's causing the whatever vehicle in which that piece of DNA travels around to keep itself in its in existence through generations another example is a work of art or a good piece of literature name I mean exactly yeah and also good explanations in general in physics they keep themselves into existence by being you know by keeping ourselves into school textbooks and and and popular science books and etc okay so that kind of information is a special kind of information because it can cause transformations took up the DNA can for instance cause the cell to perform certain particular transformations on the environment and you can also in particular causes transformations to the end of remaining time creative in physical systems and that kind of information we start the theory we call knowledge because this sort of the energy comes from Papa who was talking about me introduces I do objective knowledge that doesn't have to have a knowing subject so it's got to the case of DNA there's no need for any sentient being to know about it for it to be causing these transformations that it can cause and we call it knowledge that in the sense of popper for that reason okay now knowledge is as I said instructed Hitler sees a bigger kind of information can is capable of performing certain tasks and that are kind of tending towards making that piece of information remain instantiate in physical systems and that kind of thing turns out can arise in our universe and it also turns out that it arises by our knowledge creating systems and we only know humans as current instances of such systems the many others a eyes are the same kind of stuff and of course the process of creation of knowledge is unpredictable and therefore intimately connected with the existence of what one would like to call freewill and this is how the freewill issue is connected with the knowledge creation issue which is connected to the rest and strategy by a construct a theory of information and via the theory of the universe our constructor so now how does construct a theory handle the issue of free will or the existence of choice etcetera and that's of course an open question but let me just say something about it now the reason why it's impossible to accommodate free will in the parain conception again is because of the well because however you look at the laws of physics either you think of dynamical laws that are deterministic in which case there's only one path that the universe goes through or you think of the laws in terms of as them being kind of stochastic in which case yes it's true that you may have a certain probability for an event occurring but in the end there's again only one path that the universe goes through right which would be the one that happens to be by chance yes then it fits up very nicely he says you know if the universe is fully deterministic then it just looks like a line from the gods eye view yeah from a probabilistic God's eye view it just looks like a branching tree and either way is fixed yes yes and that's what and in fact you will follow only one of those of the branches so the just one path in the branching tree yes in any way in any case so you can't incorporate in this description the idea that something that say you know Fred chose B but could have chosen a which is the heart the kind of core idea that's connected with the possibility of having free will so that's what the great exception has to say about freedom in a case construct the theory the link that the kind of handle that constructor theory may have on the problem comes by the notion of knowledge and that's because the stuff that makes Fred choose a and not B when faced with the option is to do with the knowledge that it's creating is in his brain you are in the process of decision and that creation of knowledge if it's truly creative should not be predictable so there should be a fundamental unpredictability as to what the output of the thinking will be but this clash is of course with the fact that we also know that you know the stuff that goes on in that brain is to be described in terms of the ultimately in terms of the brain configurations that Fred's brain goes through yes and of course although it doesn't exhaust understanding what's going on in his brain by you know giving just the state in which the brain is in the various moments of decision whatever description one gives of the knowledge creation the higher level must be consistent with the fact that the brain is indeed undergoing a certain dynamical evolution so a new idea comes in which is the one that motivates us to the choice for kruis on rather than biscuits for breakfast yes and we have to be able to regain and be compatible with the lower level description of you know atoms in Fred's brain moving from one configuration to the next one according to the nominal goals but the same time we would like also to be accommodating yes there is an unpredictability in this process because Uncle Fred brings about the new idea in his brain no one can predict what will happen so as you see we are talking about segment to do with what one can predict about what occurs what will occur in from the brain and here comes in the fact that arguably and as I said this is speculative the a particular brain configuration that corresponds to the new idea that that goes for biscuits rather than cross on can be only brought about by a simulation of Fred so if you had another you know if you could simulate the universe from the beginning up to the coming up of Fred and then this momentous choice between biscuits and crossbones yes then you would be able to predict what what the original instance of Fred will choose yes but of course in the in the meantime Fred will have made this choice and so the idea is that unless you already have the knowledge you cannot make the prediction about what knowledge will come up in Fred's brain ok for the choice to be performed and this unkind of unpredictability is the sort of thing that the knowledge creation is a signature of knowledge on knowledge creation is a kind of feature that knowledge creation has which while in the parading conception is impossible to accommodate on the face of it because all these statements that I've just made in terms of simulation and impossibility of etc are all statements about certain particular computations with given resources being impossible right and those statements are not at all fundamentally in the operating conception but are fermenting constructor theories however the inherent unpredictability of knowledge creation may be possible to accommodate in constructor theory and that's one of the reasons one of the roots the handles that constructed here you may have a mando this prequel issue okay but I mean there's a difference between whether fred is predictable and whether his thoughts are determined right so it might not be the case that you could ever build a computer that could keep up with the universe in order to see what people do next but it might still be the case that his decisions are fixed by the state of the universe well there's a little ambiguity about what one means by is fixed fixed by what so so really what one would like to be able to accommodate is that when the process of creation of this decision takes place at the level of knowledge creation you really bring him about a new idea that wasn't put into your brain by anything really okay so and at that level if you can make a statement about unpredictability you are freeing the entity that's making the decision from the fact that in fact you know it's his brain yeah he's undergoing a sequence of configurations that even if you want to think in the terms of the reigning conceptions were set to the start so the question is can those two statements be compatible the one about Fred choosing and the one about the rules being you know the the dynamical laws of the various atoms that compose his brain being a certain kind yes and the answer is yeah they are well I mean anything that I wanted to say is that I mean it's lame I doesn't they will I'm very convinced by Dan Dennett sort of version of compatibilism right um on this question which I'd end up ways of approaching it but which say that the key to understanding freewill is not necessarily at level of physics is it's at the level of biology and of psychology and what you're saying doesn't sound too far from that in a way and do you know Austin's part in philosophy no so that this philosopher is on a path in green and it's got one last shot to make and he misses it and he goes ah I could have done that right I could have done that right another one comes the naysaying physicist or whatever and says no sorry the condition of the universe two minutes ago was as it was and you couldn't have it couldn't have been otherwise that um and then what Bennett says to that is that we are being very unsure edible in our definition of could basically and that when Austin says I could have done that I could have done that he's not really talking about the universe of one slice of time he's talking about his general skill as a golfer and that only comes into focus if you watch him play many shots and you agree yes yes he's pretty good and he makes ninety nine hundred something like that and and then thinks that that's the key to understanding freewill really but it's it's about our capacity as agents rather than worrying about being fixed by physics moment by moment I think there's a subtle difference between this view that then it has the one that constructed here you may be able to bring about okay so if you're a physicist there is a apparent problem to do with the feminism or even stochastic so many signals or su casa close yes yes if you only want that to be the fundamental way in which to describe reality so either you say that the freewill is really in an apparent phenomenon or if you would like to incorporate it into your physic worldview then you have to develop new tools and it may turn out the Dennett's idea is a wave interpreting whatever physics worldview that would be yes but we need to address the question in physical terms in a kind of more precise way before yes well I think I think the difference may be the difference between you and a negative thing is I'd rather be happy to to say that will is is an approximate concept to relative to physics it's still real exactly that it's too real but it is approximate yes and you want to make it precise yeah and also the property that the brain can perform a choice is a kind of factual property of the brain and when I say counterfactual I mean something to do not with what happens to the brain but what could have happen I mean one so it's got to do with four transformations or possible minute etcetera and what transformations it can cause so as you said in constructed here that should be an exact statement of some sort and it would be interesting to figure out what that is before so the and I think instructed to you with regarded as the way of incorporating freewill you know to an integrated view of fundamental physics okay so to close I quite like to talk about this sense of optimism that you and David Deutsch derive from structure theory which has a lot to do with this idea that if a task isn't real now by physics damage possible at possible with knowledge so come take it from that yeah yeah this is what David calls kind of momentous bekata me in the sense that it is unusual to think that either something is ruled out but the laws of physics or it can be brought about given that we put enough effort into it yes have to pretty simple terms and yet this is this seems what mr. speaker the constructor theory provides us with so it's not good to say that we haven't actually yet achieved something like say a universal computer and therefore it may be the case that it can't be build hmm what we should do is either find the law of physics that says it can be build or try to think harder about how to do it right and there is no escape so in in both ways and there's something cool to discover in one case does a law then we don't yet know about you know something to do with past cosmology or some considerations to do with the fact that we cannot assemble this universal computer and and that would be a very interesting fact or we have the chance that there isn't such a law and and if there isn't then we should actually think harder about which is what you know my colleagues are doing and about how to implement the universal computer right and it's not good to say well possibly perhaps it can be healed and you know just just think that we can get away with it like it and and I think it's a positive thing to say because in as I said in both cases we will have learned something nice and interesting about the laws of physics and the end of the thinking process and in regard to broader implication this basically says that it's up to us realizing all the various beautiful possibilities that that that the laws of physics allow and and allow for and and therefore it's kind of saying you know there's a lots of resources we have you know apparently we have this knowledge creating power so we can make use of it to do something you know achieve transformations that can improve you know our environment in the way in which we interacted it at and so on and so it's stressing the fact that PD humans within a set of living things have a sort of beauty as well in the sense they think they have this capability and they should do something about the kind of and and so I think this is very positive way of looking at things and then I'm so if constructively pans out and it works as hoped this may also have implications for perhaps the way we think about ourselves as well

Channel: Joe Boswell

Views: 32,634

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Id: EXaWbQCSY_M

Length: 66min 29sec (3989 seconds)

Published: Sun Nov 06 2016