 Well, first of all, it's the first seminar of the year, so welcome everybody. This is the first seminar of the year We understand that you have been re-elected director. Ah, yes Thank you for your confidence I'll continue ruining things in exactly the same way that I've been ruining them already promise you the Schedule for other seminars, especially this this goes out as well online and for YouTube folks We finally do have them up. I put them up this morning. So on the Cephes as website We have an event calendar. You can see all of our upcoming events that we know about There is also go ahead and do a little PR mid-October the Post-Arwinian Society seminar is restarting again for this year This is a collaboration between us and the folks over at the Hoover chair Some really interesting speakers have already come out and we'll be coming out again This is going to be this is going to be fun as well. All of that is on the event calendar So you can see everything on on the event calendar The calendar on the website. So Yes, the first topic of the year is all of us. So Alex on so It's my honor and privilege to introduce you one of our home now It's it's a tradition your first out of us seminar. Nobody wants to come. So there's always a local one This has nothing to do with quality each year. It's a very good start. I remember last year. So we've Since we have a little bit. We're a little bit late in the schedule. I give you the floor Kevin Well, thank you everybody for being there to the first day now. I have a pleasure to start If I at some point if I don't speak correctly enough, please stop me because I Okay, so we stalk that of this talk a bit changed from what we have seen on the poster Basically Take the presentation part out. It's just gauging what's physically meaningful and it will talk about the tension between fury and experiment particularly So the name of this talk in yen would be to convince you that due to the importance of a similar group for an interpretive process in jr you have a specific case aware of Authority for experiment with a different theory diverge and there is a tension to resolve that you have to resolve actually if you want to Do metaphysics or if you want to pursue physics that work today and So it's a tension that is not trivial at all We will consequences for both physics and philosophy So the outline of the talk I will start by discussing the two authorities that I've just mentioned For science inside science, this would be a talk within science And no question for manifest image of the world at all Then I will briefly Go through the symmetry gauge representation definition that we use in physics and philosophy physics because I expect that maybe I will talk briefly about the interpretation of symmetry and gauge according to the two approaches that we have defined in the first part of the talk And then I will go to the jr interpretation Okay, so two authorities in science There is a question that seems to have given speech inside physics and physical committees throughout history About what is the legitimate authority to decide and to arbitrate physical debates And it's not a general question and people have their own concerns to it In the 60s we had the Celas philosophy and scientific image of man That made the popular the idea that has manifested the scientific image of the world So you have two different authorities already there one coming from the main line from Our day-to-day life and the picture of the world and you are coming from the science and science practice And but actually there was another speech in the 80s inside the philosophy of science community Which has been termed termed practice with notable philosophers such as Akin and Gorka Schreitz And this kind of this new branch of philosophy has Have been diverged from the orthodox one by saying that the real authority of science is experiments and so we should do More philosophy about experiments rather than just seeing everything through theories as we used to do before that One thing that that remained though is that in physics they didn't follow the term most of the time And in physics they are orthodox in its way to approaching so for them theories are always are still the The thing that you should look at if you want to understand what is the future such a picture of the world And it's not the experiment of the experiment as just there are just there to test theories And the more fundamental theory is the more the closer to the truth and the closer to the real picture of the world it will be So you have two different traditions Nowadays in the future of science these two traditions from my experience at least they don't seem to attack to interact very much So Providing that you are allowed that there is genuine logical questions that You can ask with experimental practices You can divide the two traditions as two different ways to approach science One which is which is stopped on Well, the autological part of Autological relevant part of representations are coming from theories are coming from The authority of theories and that they mostly transcend the specific context of applications And you have a waterway approach, which is more in the time to practice tradition Which take as a source of authority the resistance of the world so the experimental part of Science and practically the scientific practice of the will of theories and they are the ones that highlight the physical physical physical reason part of our presentation As I said at the start it's not a question of manifests against scientific both approach and scientific And I will not talk about manifests at all during this talk However, and I expect that in the end since our practice are based with our Our practice are made of humans Probably the bottom approach will be closer to Philomenal tradition of the physical tradition or Manifest tradition of doing metaphysics and physical philosophy in general So at the start what may What may expect that their proof approach coming from two different sides will be complementary so To just train different part that are actually not related and the clash together or they are trained the same part of science But if you look at if you can yet how both How you can talk and represent things in experiments And compare to how you define things in theories You actually see that you have two different the two very different pictures of the world at the very start of the Investigation, so I've written here a quote that took from course with the first technology And one of the one of the few book I go about future experiments in physics So he's basically saying that when you have experiments the way describe the process and the easily functions Your experiments are designed to something so there are functions and the instruments that you use they have functions to do something And it's different from the way Because everything you see is structures and how things are related to one another without any question of design and The way to how things are made Do not do something So here already you have the divergence that you see It may be trivial if it was complementary or the same so if it was complementary But actually you can show that there are some parts of physics at least Where the two picture clash clashes It can be seen with very simple Instruments that we maybe have all used in the high school day before the mercury thermometer basically mercury is just An instrument that you use in the physical experiments to measure temperature But at the same time it's also technological instruments that required a lot of design and a lot of thinking what In order to be able to do what we use it we use it for today So in this this is the object with the two picture of the world Functional the spiritual picture that are clashing together And so you can see that there are tensions that are not trivial and not easily resolved If you take if you look at science from the home both ways So there there are only a way to To resolve the tension and to start just go full on racism like radical imperialism There is no question of ontology is just mental questions and Girls there is no question to go to us. It's not very interesting. I mean maybe for our project, but not for mine Another would be to persuade that the properties that That experimental practice The process of experimental practices and processes do not carry over to theories Basically, you just use them as a tool to get somewhere and when you go there You just take the Stay at the top of the But that's the usual explanation of People going for the top-down approach and the more theoretical part of it But it actually requires self-exponement because it's not obvious of Why to do so Certainly enough this project is not Developed enough that I have a way to resolve the tension. So I would just Stop at presenting you and showing you the advice function to be resolved So now there is something that is actually not real earlier I said that Provide one of those genus of investigation or the general investigation of experiments meaning that Experiment by himself as an authority and it's not really at all. At least in the physical figure of physical music It's rejected from the start. Most people don't even think about that So I could think of a few of those objections But I have to myself to start just to get the project going First is traditional Physics the theories the top-down approach and theory approach Beef that experiments is just mean to name it has no purpose outside of testing theories So experiments are just there for testing the theories. They don't Have other purposes. So in the end the result of science is theories and they are the one who carry all the authority That's one of the possible objections Another possible objection is that as well as we may all As we have Sure seen at some point Experiment are fairly them if only for purpose of creating and designing our devices that you use in the experience And the possible objection would be that by design experiment practice is a contextual human activity So it's full with Sugetivity and conventionality and contextuality. So it may not get us to the True underlying scientific picture of the world These are three three different objections that would mostly come from future physics of orthodoxy So it's very very very crude and I haven't thought too much about that About all the objection, but I would have some basic Starts the starters of objection of run sort of the objection the first is that against the first objection that That there is no Independent authority for experiments that's in history of physics. Actually, we have a lot of cases where experiments We are there before theory that we managed to stabilize and It's not explainable And measure phenomena without having theories to explain why they explain to explain phenomena It's mostly seen in the development of telescopes that were there like 50 years before the first theories of lights came out so we knew how to do experiments with telescopes and we saw some Chromatic aberrations that we knew were aberrations in the truly part of the picture I wanted to see with our telescopes before we had any theoretical information for it another Cases would be from quite famous book in the future of science practice community, which is the one thing to measure from as of jing which show basically that The process of inventing to measure was not based on theory. It was based on a lot of experimental work before the theory of There and far before any statistical mechanics was there to explain the Form and film So, uh, since family now discover and stabilize experimentally before A lot of time before we have theories There is some authority that is coming from books experiments. That's independent from our Our theories and relations And this this phenomena are also stable enough that they survive through theory changes. So basically they are They are still more resistant than theories. So there is no reason why and they shouldn't have their own authority Uh, and actually this this resilience of experimental measure is something that is a great idea I've actually taken the physics to accept new theory. You want your new theory to explain the old Experimental result that you had with the former fear is if not, your new theory is dead at the start If you want to answer the objection that the what theory like this of experiments Uh, if it pertains to the theoretical framework that you will have to use in the door to understand your experiments as I said before, uh, you had I guess a lot of Stabilize the middle of that arm but for before the experiments The theoretical the theory is all right to explain. So It's not necessary to use theory to study this experimental practice in phenomena And if it's related to the Devices that you use and that you have to use theories in order to construct them But sometimes you want your devices to be constructed from other theories that you know are working quite well In order to secure the theoretical Experimental stuff that you are doing without relying on the theory that you may want to test with the experiment that you're doing otherwise And uh, regarding the conceptual subjective part of The experimental practice one. Yes, that's the point and it's okay to accept that maybe in the scientific picture of the world There are subjective subjective aspects of the conceptual aspects that are physically new So as I said, these are quite It's usually First stage of thinking so if you have any comment on that Okay, so now we are going to uh be a bit to try to be a bit pedagogical because I was asked to Uh, I will start with a bit of definitions about what what we are doing And we're going to talk about symmetries and physics And just for physics usually so you may maybe familiar with the idea of a semantic approach of theories is basically a way to define theory and the orthodoxy in physics so for ease of Demonstration of explanation. We just assume it and not talk about the controversial part of it So a semantic approach of theories is basically the idea that the theory is nothing but the collection of models that you can That is defined through the the laws of theory So you may equivalently talk about the theory and the laws or about the models that we use to whether they have a very defined fit So there is a way to uh to define uh the two reasons for presentation in physics So at the further left of the At the further left, you have the world which is supposed to be a manifest being made if you want or not be in the world The dotted line that's crossing over the scheme scheme up is to uh separate between the manifest and the scientific And I think to the right is the scientific part of the presentation So when you see it in this picture, uh, you have two different levels of presentation in physics That's that uh, right? That is not uh a necessarily typical way to do it, but uh, it's not useful or anything, but if it's interesting physics So the p is basically a physical world It's a world according to physics So it's a presentation that are already highly idealized and uh While you are negating a lot of stuff from the world in order to have a physical picture of the world And what you don't you don't have access to would be what you have access to is the m And the m prior prime, which are mathematical that you use to present the physical pictures that is there to present the world So it's a two-step process So that's basically what I've just said the With for example, so the conceptual model of the tariff in the new world, which is the p that was at the middle of the scheme And basically an example of that would be uh, taking the moon and vf as point bases are making a Around each other with interacting with gravitational forces And the mathematical description of it, so the m that was the further right of the picture would be the orbits of that the mathematical orbits of of the point my spot The interaction point bus will give an equation at this point in our motion No, we may wonder what m prime was Because we already got the m Basically the idea of having m prime m is to show that you may have some surplus mathematical surplus In your mathematical presentation, so basically the mathematical structure that doesn't carry over to the physical picture of the world So basically doesn't carry over either to the world directly And in your world you want to say that you don't have access to the structure and it's physically irrelevant To the physical orientation of the world It's just there in order to secure your mathematical presentation It may be coordinates, which are just a tool that you use in order to have A more useful picture of your physical system Or, for example, I use complex numbers, because you use a lot of complex numbers in physics And obviously you don't see complex numbers in the world Yeah, so you didn't see the color I'll go back The left picture was supposed to be the representation of orientation It's a presentation that is Taking stuff out from the world inside of such a grid of presentation and the overall rating p and m is supposed to be Rating structures and that's Not something else Okay, so now that we have these ideas What is a symmetry transformation? So for a given structure A mapping of the element of the structure and the element itself Is called the symmetry of transformation if it preserves the structure of S Of the structure that you start to give And we say that if you have A lot of these transformations they form a group that we call the symmetry group of S And a lot of the time in physics you characterize Objects, geometrical objects by their structure, by their symmetries, rather than by their physical properties or mathematical properties Do you have the dual notion to symmetry in variance? Obviously if you have a symmetry If you are symmetric in torsionation, you have some integral parts And these are notions that are only present in physics So the symmetries that are most interesting in physics are symmetries of a laws of dynamic operations Which are our favorite of our theories So granted the semantic approach we can define the symmetry of the theory as such For an even theory t and its collection of model theta The map is a symmetry of t if and if, if and if two models m1 and m2 such that m2 is the image of m1 by f could present the same physical state of error Which by which we mean usually that they are empirically indistinguishable Okay, so now that we have made A full four definitions, we are ready to categorize symmetries which will be useful later There are several, several distinction that we make in physics According to the type of theory of a transformation that your symmetry is part of You can say that symmetry is active or passive an active symmetry is a transformation that relates to two different models as you had before That would be an example of an active symmetry that takes one model and goes to another model of the same theory Or you could have a passive transformation which is part symmetry which takes Which is relating different coordination of the same model You could say that symmetry is continuous or that it is discreet The continuous symmetry is basically in that Under continuous transformations Like the translation of whatever system you want in the mechanics you translated by how much Meters you want Or discreet symmetry which is basically Just judging parameters Discreet transformations like the time reversal in physics, the motion of physics most of the time are Inviance against the reversal of the error of time, that would be an example of discreet symmetries You know about distinction that We won't use too much is x star versus internal Basically an x star symmetry, an x star is a symmetry That involved changing of location on the spacetime, the spacing time And entire symmetry is an invariance transformation That does not involve anything to do with spacetime So basically the x star transformation x star of symmetry would be a rotation of a two-digit system You rotate them It involves changing your location spacetime, but the symmetry remains because you only have two-digit Or the entire theory would be taking the two particles, the two massive particles just switching them and does not change anything But you have technically an internal transformation The only thing that we've been interested a lot of definitions that we had earlier are these two distinctions Most of the time we talk about continuous, or actually all of them we talk about continuous symmetries And there is one mathematical properties of these symmetries that would be kind of useful Which is that they are all sharing the same representation in mathematics Which we call the Leigh groups for the conflicting alternatives Basically it means that every internal or external symmetries They all, if they are all continuous, they all share the same mathematical structure So what you say about one carrier is about to be about most of them Okay The last characterization that we need is different in what's in global symmetry and local symmetry So the global symmetry is characterized by the constant parameters like if you take If you take whatever body in Newton mechanics and it just You apply the uniform motion velocity to it It would be a constant parameter of motion that you apply to a thing, so it would be a local symmetry And local symmetry would be a transformation that's characterized by continuous function So that's the example But basically it's just that you're allowing your transformations to have parameters that are not constant Intuitively Global symmetry groups are just a group of local symmetry groups It's just that the function is not that you take is constant So it's as if they are so close to one another And if you want an intuitive picture of a thing that is not accurate Projected into space now, so we are not talking about the laws anymore, but how they are looking in the presentation The global transformation would be seen as Taking the same transformation in all the point of space time And the local transformation would be like if you choose that at each space time the different transformation Okay so No, I'll talk about important concept in physics in modern physics, which is gauges And most of in day life the gauge you may be familiar with the concept the gauge is A scale that you use to measure stuff like you would have in your car your gauge or your motor you have fuel gauge or whatever and you can use different units to prioritize this gauge And in the term of The presentation the stream of presentation When we add the tour To a mathematical model for the same physical presentation you could say that that has two different gauges that just coordinate the physics differently okay, so No, no tearing over to the modern physics of today What we call a gauge symmetry is usually just a continuous local symmetry. So I brought it to the distinction again earlier And so a gauge group is a league group characterized by continuous functions Okay, and accordingly a good theory is a theory that is Who's in alignment equations are violent against Entirent under engage Okay, so how do you interpret these symmetries and gauges in physics? Are there are mere circular structures or part of a primary scenario or do they have physical significance That's one of the main question that you can ask about symmetries Uh, intuitively speaking your gauge or symmetry would have physical significance If you'd have a corresponding symmetry or gauge inside your physical part of your presentation So if it was just not a fix I'm not just The mathematical tearing over of the structure, but see that it's changed something in the in the physical presentation of the one Yeah Bottom is cut but it's just that I simply think of simplified model because I would have used active Active series instead of passive series then what we have to have four different The circle to evidence Okay So why is it actually interesting to look at symmetries in physics and why what is the importance If you look at history of physics again You would see that the research for symmetries has led to a lot of advancement in physics and a lot of the time Looking at symmetries can inform you but the underlying vertical symmetries are the underlying form of your theory Uh, the main example that was that the The prime example of a symmetry Used essentially the world used to model theories is the gaio chip experiment that you may have heard of So it's a quote that is that they've taken from the translation of gaio's Main book Basically, if you shut yourself With your friends in the small cabin and under a lake of some some chip Without having any access to the external norm And you have with you animals, fishes, whatever balls And you send your balls to your friend and send them back to you You wouldn't see a difference whether the ship is moving on us if the animals are running around You wouldn't see a difference if the ship is moving in uniform motion, sorry or not That's so basically if you're inside of the ship you wouldn't see You wouldn't see any difference if the ship was moving or not You couldn't do any measurement that would reveal if the ship is moving or not However, if you are going to open the window and look at the shore, that is just in front of the ship You could see if your ship is moving or not, but you just couldn't do from the inside of the ship If it was a totally, totally closed system, you wouldn't be able to do any measurement to see if it's moving or not And that's the main idea behind the Concept of initial frames and that led after a lot of work to mechanical mechanics So apparently the other thing is more controversial, so to speak Another kind of symmetry, but usually we are exaggerated to theoretical change Is because of moral experience which shows that there is a speed of light, there is no direction There is no searching as in the FIFER, but it was one of the Positions to carry over after the mechanics to propose that there is absolutely a restrain of the universe But apparently it's slightly more controversial Now what is maybe a bit surprising according to In contrast with what I've just said is that if you look at the physics community or even in physics You would have a lot of people who think that symmetry is not Physically relevant, they are mere similar structure, so they are just other ways to describe the same picture of the world So for great theories, for example, you have people who qualify them as simpler structures The descriptive fluff And the guy who said the descriptive fluff is one of the greatest physics that we have And he says that it's basically the common way to see gage in physics So we should adopt it in future physics as well according to him Okay, so right that is the tension that we have in the understanding of interpretation of theories So that's the tension, that's why what is the quote that is just summing up the tension that I just described So there is some kind of tension in two aspects of symmetry in physics On the one hand there is a widespread consensus that two state of affairs created by symmetry transformation are really just the same sort of affairs different to describe So the field for physics point of view That is to my friend I will do the fiscal theory of related to our symmetry transformation There are those models of one and the same physical state of affairs So the symmetry is actually formal, they have no clay over to empirical stuff But on the other hand, as I said, if you look at the history of physics There is a lot of contra-examples, but where we have thought that symmetry in the world We have a core rate in the theories And so we have a nice paradox, that is a system solved over there by our good friend Quentin Ruyon If symmetry transformation creates a presentation of a theoretical state of affairs How can they have any observable consequences Including presumably the one for which we are handling affairs Okay So there is a way to dissolve this paradox As so often as when you talk about symmetries I think I've put the emphasis on that one, I was talking about the value of ship Actually, you're most of the time you're talking about symmetries on the linear system And you should recognize that your system is not Most of the time it's not a full space time, it's not a full universe So the system is part of the notion And if you're in the environment, there is a good chance that you could observe Symmetry of the inside of the system So that's the thing with the value of ships, when you open the Window, if you are in the shore and you're looking at the ship You will see if the ship is moving or not, even if inside the ship, the symmetry is on the top When you go Okay, so Vis-à-dia, that you're most of the time in physics, you can't separate A subsystem from its, either a subsystem from its environment It's a way that you use most of the time in physics to have models of Small part of the world And it's how you can set some theories, some symmetries, have empirical Relievance, even if they are mostly risk, people are just trying the same The same set of affairs So basically your physics is the same behind it But you could, you can see it if you're outside the subsystem system In first instance though, it seems it's not possible to do the same thing with gauge theories Gauge, gauge theories On the other side, gauge theories are continuous So you can change their value at each point of space time If you're talking about the gauge inside your presentation So, if you don't pay too much attention to the boundaries of your system You can always set up symmetries to be the value of the gauge symmetry inside the system And the value of the INC, our set of systems So the symmetry will guide over to the world And then symmetry is the symmetry of the world and not of the system of the world That's basically the orthodox way to understand gauge symmetries One of our blocks way to understand gauge symmetry So now I will talk about three different ways to understand symmetry According to what I've just said That would be the distinction I've just made and the picture I've just drawn So the doxa of a field of physics is invariantism The idea that two symmetrical models are just matching surplus structure in your theory And they are alighting in a single stable state of affairs And it's something that is a long standing tradition in physics That comes with the idea that we advise invariantism Which basically link invariance with objectivity Because something that I've already, according to Nozick Is that it's been going on for a longer, longer time And we have been doing that in physics We have here a definition of what objectivity means for a while Objectivity means invariance with respect to the group of automorphisms So the group of transformation And it's something that is still present and still the most orthodox way to Do understand symmetries in physics and physics So here is a guy who said that gauge freedom is an unspecified fluff The point is that in the theory with gauge freedom What is real or objective is what remains after the gauge freedom is removed So basically the gauge freedom is just I think you can have surplus You cut it out and you still have a sense of physics And it's something that you will see in other texts From over famous people in physics So from the invariantist standpoint Gauge freedom is still distracting you away From what is behind the mathematical structure That just relate to the physical structure of the representation So there are just something that is there to mislead you into Thinking that there are some reasonable events For ontological and interpretive purposes So at the time they are paradoxicalists And they just advocate for cutting out the surplus And working with reduced theories If your purpose is to interpret The physical reasons of your theories But they don't contest the idea that gauge freedoms And coordinate systems and over symmetries Are very useful when you apply it to the world Just that it's simple and very interesting Because clearly these guys Are part of the ortho-exical way to physical physics So they are one of the total approach What is really relevant is the theories not the practice Since gauge freedom is mainly in practical So it's mainly used in experiments and essential practice It's a secondary, everything that is relevant is in the statistical theory Okay, so now a middle point Between the invariantist, the total approach The bottom approach that I will go to later In the famous article Rive and Duolas are trying to seek final analysis Of this subsystem and their division Used to pass on the paradox that I showed earlier The way they do that is that they atomize the ratio To the invariant and the subsystems And they show how the symmetry relates to the distinction Between what is the subsystem and what is the environment And the most important part of this paper is that When they are talking about this division What we are talking about that was not talked about in the previous papers That we are just, that are all in the physical approach Is that we are talking about Pragmatical consideration of how it relates to the system Because in physics we always assume that You can take subsystems of the world And you can just say, well, it's isolated because All the forces that act on it, also the systems are negligible But even if you are making jimbal, they are still there So it's always an alienization So you have one trigger the boundaries when you isolate systems And in the context, these boundaries are context-dependent So you have a semi-pragmatical approach Of understanding symmetry So it's kind of familiar with the fully top-down approach theories First and the bottom-up approach practice Pragmatical approach can question first And the important point is that Basically in jimbal what they see is that Some gauges can have physical and theoretical reverence So they don't agree with the previous position About which symmetries are physically relevant So the last approach about symmetries Bottom-up approach So again, our friend, Quentin Royon He's a physicist, a friend of the symptom So yeah, I've written this in a good favor But I wish I had written it myself Because basically he's saying everything that I wanted to say before coming here So it's a good example of what I had called the bottom-up approach at the start So starting with a practical consideration about practice And taking them to mean something and not just a simondary to the theories So the article is basically an attack against the third position that I showed The valentist-reductionist pictures Is very against the reductionist parts Because then if you are a fully-reductionist You have just eliminated all the symmetries And you have no way to understand the symmetries that you used to infer the physical symmetries And in the end you have some issues of understanding what's happening The example that he talks a lot about is an example of a surplus symmetry That you shouldn't get rid of It's the idea of a coordinate system And the rate is usually the coordinate system Basically the idea is that you can parameterize every location in the world by numbers It's usually going to be just a restructure But if you look at it from a practical point of view, it is very meaningful From a private standpoint, they have a function in the practice in science Which is to be indexical devices that refer in context And tells us how we should measure the quantity of the quantities that the model describes So they are applying a scale to physics So that we can do physics in context So for him interpreting the coordinate system in context Amounts to adopting a particular class of operand solidization For position measurement, associative with coquette reference So basically when you are choosing a coordinate system You are choosing how you will be measured along the length of the table Or the length of whatever else you want to measure So it has operational meaning So it is useful in practice and you shouldn't get rid of it If you want to understand how you practice How you practice science So the important part in contrast with the virtual approach Is that it's related to what scientists actually do And not what they end up with Not the result of their practice So this practice you can see is giving meaning to What was found before to be near structure The position that he... He calls that perspective sense In the position of the previous dimension position Which he calls the universal sense Because it promotes a view from nowhere It's a view where perspective and creativity have absolutely no relevance And that you should get rid of everything that has to do with perspective And if you want to raise your follow content And if you accept the perspective sense You have a new understanding of what is the structure in physics For practical context Basically they are a model structure That represents the possible perspective that you have On the physical system that you are trying to study So they are exploring the structure of possible perspective On top of the physical aspect That is somewhere where you can link The water approach is closer to some manifest picture of the world This kind of you have an object, a system in this case And you have to adopt the perspective to look at it This kind of an instance of some kind of symbology with the water So this text is very long so I won't go through it But basically the important part is that through this approach Which is taking from the other side of the other two It doesn't end up with the same symmetries having relevance Basically for all the symmetries, half the physical and logical relevance And the batch of symmetries That is different from the other perspective So you see that all the three approaches They all die in large in the end on how they interpret the symmetries In our presentations And as I said, it's a clear water approach The justification that you use for this position Is that it's more faithful to the scientific practice Of using the water So a summary of this approach that I just talked about We have seen life from three different positions On how you could interpret symmetries One which is the orthodox, the artist one, top-down One which is middle-run with some problematic consideration But still the former theoretical approach at the start And the fully bottom-up approach Or as close as possible As as simple as it is at the start And as it seems that through this approach That all shows a different rhythm part of symmetries You can see that the tension I talked about at the start Between the different approaches The way to interpret physics Is actually something that carries over To the actual interpretation of physics It's not just in my mind corner Or in my words The choice of this particular interpretation Is not chance at all It's because as I said at the start For the symmetries of GR You should say what is GR Generativity, something I didn't say that at once No, not once Generativity I wrote it in the title, right? Yeah, it wasn't written with you No, but for people then No, you're right Sorry So yeah, generativity theory The main interpretative points Are related to its symmetry group So obviously what we just chose Is kind of useful to understand What are the meanings in generativity Okay, and why generativity as well Is because I believe that it's Most spectacular case of tension That we need to resolve Between the bottom-up approach So yeah, it's not written So it's generativity And the orthodox pictures There we go It's in two different forms The generativity or generativity Which is the same thing So to date it still is our best theory To describe the interaction The gravitational interaction And the geometrical aspect of space-time It's basically defined by Following three elements The field, which is the gravitational field And also the metric That is called the metric Because actually the gravitational field Can be seen as the space-time of Gerativity The gravitational interaction Is basically a geometrical Interaction between the motor field So you have a genetic equation Which tells you How masses move in your space-time And how they move in the metric That is defined for the equations Of Einstein's ancient equation Which are the main field equations That you use to define The structure of your space-time And the curvature of it And how it looks And we define it Contrary to previous theory We don't define it as a start It's something that is fixed It's a part of these nice equations This equation is actually 10 equations So if you want to If you want to have fun doing math You can write for that I've done it, it's not fun So yeah, the geometrical space-time Is not fixed To reserve an equation And it's related to the way Gravitational field relates To the solution of energy And matter in the universe If you want to know What each term means It's not really useful The only thing you need to know Is metric Which is the geometrical aspect Of space-time So if you follow the theoretical approach That I defined as a start GR can be defined As a collection of space-time That are the solutions of the equation That I showed earlier Basically what you find in literature Is that you define models Through triplets Which is a differential manifold So it's just a geometrical object It is there to be Like a bearer space-time Like I imagine With a few geometrical Structure on it That allows you to physics with it G-minu, which is the part That tells you what are the distances What are the lengths And the proper time that Processes take In space-time it tells you Everything you need to know About the length Time All these kind of Informations when you physics And the O is just a generic term To replace every geometrical field That you would like to put In your field Matter field So as I said So the very interesting fact About these equations is that They are invariant again Under a group of space-time symmetries Which are what I call the difformorphism And the deform is dif So it's hard to say But difformorphism Is an up-frame map That is from the text From the space-time and put it back to the space-time It's just an arbitrary function That is sufficiently smooth And basically you could Apply whatever smooth function You want in your space-time You would just circle around The class of solutions Of your space-time Of your equations So as I said it's a continuous map So in the terms that we had earlier It's a continuous External local transformation Continuous because It's a continuous map Local because You can change each space But I'm going to have to set The value for the form of field And it's hard because it takes Stuff and moves stuff around in space-time And the nice thing is that Mathematically when it's Presented by a group It's characterized by continuous functions So all the debates that were earlier But were most of the time not settled In generativity But mostly in quantum physics example Or Outside the physics example Since all the case transformations Like such as The consequences can carry over Ok One thing that I will need also Is that as I said at the start You have two different ways to see transformations Active and passive way And so accordingly you have two different ways To see your morphism variance Either you take it that They just They just change the coordinates in your space-time And they don't take you from above to another Or you take it as they are Deliver equations And then what they are doing is not Record nice your space-time But they are shifting the fields Geographies over your uniform So they take you from a From a model of a theory to another model of a field And it leads to The very famous And much discussed all arguments That you may know Or may not know but I Will talk about it again Sorry if you know it So basically the idea is That you can have Space-time as Nice as you want Something that is not prevailing In terms of your space-time As a surface For which your Particle trajectories pass only once You could have Time travel to have Different equations You can have the nicest space-time you want With every properties Guaranteed that The trajectories are Aetherianistic as you can Since you have Different morphisms and variants And you have the active understanding of it What you can do is that You can select A hole in your space-time A region of your space-time But you can shift You can just apply the uniformism Inside the hole Keep the rest of the space-time fixed And so you would have Shift the solution Of the trajectories For particles inside the hole If you believe That the models Could not relate The same physical situations So if you break That is the principle of Which one is the one Differentiation principle If you don't believe That you believe That you can distinguish Directly from the situations In the space-time You would be in Kind of Weird position because then Your trajectories can be shifted Any way you want By just applying different morphisms to it So basically it forces In the mind Of people who present these arguments Which one of each was The guy who was saying that He asked the fifth Again, always the same guy Or Einstein Or Einstein as well, that's true So basically If you don't treat the deformism as gauge symmetries In the sense that They are just a restriction of the same physical situation You are threatened with internal determinism Okay I was in the orthodox picture By the way, so the Okay So no quantum gravity Which is where the fun happens And I don't have much time to Write these slides so I don't know how much Understandably it would be A few people before If you don't know, generatility so far Has passed all the empirical tests that we've run at it Varietas being the Detection of gravitational waves in 2015 That led to a Nobel Prize Which you may have heard of But we know that it's not a final theory We know that there are objects in the universe That require us to couple quantum matters With equalization fields So we need a theory That goes beyond generatility And incorporates the quantum part of the physics So we need a few new theories And the question is how do we do that We expect that a new theory If it's not a Today I'm creating a new theory That I've advised by a lot of prospects for that So far, if I'm not wrong, correct There is a good chance that It will incorporate Features from generatility Features from quantum physics So each proposition can be seen as A proposition of understanding What is physically and And both quantum physics and generatility So whoever wins at the end Is the one who had the better understanding Of physics today Okay so that's what you can talk about At much time to write So I'm sorry if it's Yes you So the equation that I have I showed you earlier Is written more or less In what we call the Laman information So the Laman information Is not a description of a system That you evolve step by step What you get When you do the equation You get the full history of the system So in the context of space time That's the end of the equations And That is kind of an issue Because the only way to Contize theory so far Is to put this in another For another formulation That actually takes A system to define the state To have To be defined by a state That is indexed By a time function Or a function And so We need to have Theory The step by step formulation Formulation to be able to Do the quantization of your Theory And for our well behaved theory It's not much of an issue because Mathematically speaking you can show That there is a transformation That's for well behaved theory I could say Transform the Transformation But obviously It's not the case Of generativity If not to be I won't have a job So Basically When you Do GR as I said You have Solutions equations are complete space time For which you can re-split the field on it With different Transformations that I showed you With all arguments So what we can show is that Initial value formulation Is not well posed for GR What is the initial value formulation It's a property of theory and physics That tells you that if you have All the All the information for a given state At a given time You can say for this state how it will evolve The following step of time And that is not possible in GR Of Particularities of asymmetries in the field So when you Try to Switch to Hamiltonian You cannot do it in the same way that you Do it with the theory that you manage To put in the quantum Physics formulation What you get is This Very Poor picture You get an interminism And you get in your face space The space Of the states of your system You get gauge orbits So again orbits of Equivalence class Of states According to the Diagnostic rules So this gauge orbit If you use the top-down Approach There are gauge symmetries So you don't have to work with them Basically The thing you want to do is to Find some invariant quantities That you can use Because they would not be Interest, they would have Determinized evolution And you can do that In the constant Hamiltonian Formism If you take Any quantity that is constant Along the orbits of equivalent Representation of states You have an invariant quantities That evolve deterministically They are deterministically And mathematically is well defined But now you have an issue that you may have Not expected to start But here it comes These quantities Not evolving time They are deterministically But the evolution is pure gauge And so they don't evolve in time They are frozen And they are different In an invariant this position Everything that is relevant in physics Is invariant of a gauge Then you are forced to add on the idea That Generativity according to this formalism Gives you a frozen picture Of a generator And this is just The start of the computation of quantum field Of The concomitant quantum formulation of JR, it should go all the way To end up with a problem of time But it is a very famous problem Of Generativity To resolve this problem As I said As you see it is an issue of how You understand gauges To resolve these issues To go out of the quantum theory Of gravity You need to understand what is the gauge Of JR robots Okay So as I said You have adopted a total approach So you are an invariantist So you are forced To accept that Your physical picture world Is frozen in time For them to resolve At all times Not even in the church These are results That we have arrived at By looking forward to the new quantum theory But actually You could just have used Regular difumorphism Because In most cases There are only quantities that are advanced Diffumorphism Are constant For all of space time So they don't They don't change They are frozen in time Whichever side you want to take it If you believe that Each theory and that the gauge is meaningless You end up with a physical picture Of the world which is frozen Okay No How does it look from the other side I haven't had the time To do much work on that yet So it's very crude But basically As in every Theory when you experimentation You are forced to do them somewhere And to observe physical changes If not What is experiment I don't know So if you look from the bottom up You have to Find somewhere Something that moves And you can show that Non-variant quantities in space time Do a change The only issue is that To be able to measure or to see These non-variant quantities You have to set them against So that the non-variant Consets The quantities According to the other quantity Becomes a non-variant quantity In applications How does it work You can show that What we do in experiments At least in the most relevant Application of TR today Which is a GPS system What you do with your satellites You are fixing the physical Frame of reference And this physical frame of reference As if you are choosing a gauge For your theory You are fixing the gauge You are fixing the gauge So when you are fixing the gauge You can see what were non-variant quantities before You can measure them With this fixed reference So from the practical side This fixing of the gauge Is very similar to what Quentin was doing About the approach to the theory earlier So it's the idea that Your gauge is a relation between System and observer And fixing the gauge Is like choosing a perspective on your system And with this To show that it's not just We have physical frame stuff This idea Is sharp as one of Most renowned Philosophers of quantum gravity Which is really A traveler of the loop quantum gravity One of the main approaches For quantum theory of gravity He has written an article on that Which is quite inspiring And so it's not just Theosophy and metaphysics in the end It's also physics because These ideas He has put them forward In his new development of the loop quantum gravity And he said that the root of what he thinks Is the way to understand the GR And so it has And metaphysics and theosophy And scientific picture of the world But also in how you do physics After the divide That we have today Okay, so As I said You have two different pictures Different approaches to the theory One which is the top-down With which you end up With a frozen picture of the world One which is bottom-up And requires changing quantities Of location Space locations Time So you have two very different pictures Of the world that are actually opposite To one another So current coexist And they have to resolve And as I said, it's something that you have to resolve If you want To advance toward the quantum theory of gravity So that's more or less my conclusion Basically The dimension that I talked about Which is the two authority forces In each other's science Is cannot just be dismissed as a Non-concrete Trigel Community Divide There are consequences Both for our understanding of what is relevant In science And for scientists In some part of science And in this regard Part of science where you can see Is like If you see a lot of work is done It's easy to understand What exactly, how exactly Is applied to all this stuff And what you say about that Thank you Traditionally there's a comment But I think my comment will take The form of three questions Because it's already late And we had some technical problems So do you want the question How about once or one after the other Chronologically Okay So I think you're right That there's two kind of authorities So theory About the world And stability of phenomena But why? What is the source of this authority? Why should we philosophers Use that source To solve About the ontology of the world I see a priori metaphysition Would say Okay Maybe I should need some compatibility But So why philosopher of science Incline to do ontology Things that they are The source of authority For you, for example Before talking about me I can talk about The project on community But it's starting to rise But I've heard about Loss Vogue Which is called inductive metaphysics And basically the project is to Inductively Faire metaphysical Insights from Practices The main advantage would be that It's not some inference based relations In the structure of Part of experimental practice And if you're lucky enough to prove that So you have some transcendental part of practice And it leads to A quite Solid metaphysical picture Of the affluent metaphysical insights As for me I was given to this To approach Many by my work on general Genericity And it's a many that Don't show it in both But I'm searching for compatibility In both pictures that I found quite striking Because it's kind of Similar to another Re-received view That you have metaphysics of time But you have the divide What is the scientific picture of time And the Manifest picture of time But if you look at Physics from the practice And from the More human practical approach You have less divide And so As a way to chart possibilities It kind of helps to bridge Between the scientific picture of the world And the more mundane Or traditional metaphysical picture of the world After that, in terms of How you solidify How you legitimate Using metaphysical thing with practice There are some limitations If you're looking at case studies To infer some metaphysical insights You better have strong argument That it's transcendental part Transcendental because otherwise It tends to not carry over To other practices because Practices are more different Out of the expected theories So I can see limitations But I'm not sure exactly how To oneself but Because if you do an induction on practices You can do an induction on practices Theoretical practices That's the top down But the bottom up It depends on what kind of part Of practices you're doing the induction Because for example, if I say Human needs to Organize The Humans A typical cartridge example Human needs to use causality To plan experiments Therefore causality Is indispensable In the practice Therefore I should induce on it Causality must exist In a form of another But human are in the system They are studying Who knows If something that we need to do Is good enough as an inductive base To get to The ontology of the world It's related Because it's bodies In the world doing stuff But it's difficult to do the job The theories are as human As practices in this way If you're considering that The theories are thought by humans They are constructed by humans With their limitations I don't think there is That much of a divide Maybe more of a degree Than a real divide you can move But your point Will go directly To divide your own segue For my second question Because this is The question about pragmatic So this bottom-up approach Of the silly bottom-up Of Wallace and Reeves Which is taken much more seriously By the community of philosopher physics As you know Is to include a little bit Of pragmatic stuff In the recipe To get to the ontology Absolutely forbidden Until recently And it's always Including some spatial stuff Or some perspective stuff Or some measure stuff But if you're Except if you explain To me that these coordinates And this measurement And this spatial stuff Is extremely special Like in the Neil Kentian philosophy Any kind of pragmatic Should do the work For example Theory with surplus of structure Can be quantized Theory without surplus of structure Except maybe GR Cannot be quantized I want a quantification Because I need a quantum theory Therefore they are better Gauge must be okay Because Gauge surplus must be okay Because pragmatically It's not related to a perspectivism In the sense of To have a situated point So why this So I would be Surprised that you agree that any kind Of pragmatic considerations should be Included in an ontological discussion So why this Perspectivism is better Is the one that we Shouldn't make an induction on One of the differences That In a pragmatic consideration They are involving ways To apply theories to the world To relate theories to the world We have a lot How much consideration But how you do and how you conceive theories So there are more Resistance to the world To what you're doing But there's a lot of resistance Of the world if I cannot get the quantum theory Since all classical theory are false I'm playing the Difficulties I need the quantum theory The world is saying to me The world is not classical I have to find a way To get there More or less But it's still quantum So you're not jumping In the pragmatism train at all You're still realistic Just adding a little bit of perspective I'm trying to be As very as possible I start very very I'm trying to Not go too much For my last question Could you put back the red head pictures please One of the red head The red head perspective Can we discuss Because it's a little bit strange But I think it's quite useful For that kind of debate So any of the schema That you could put the simplest one So what is very interesting In the red head This is an old idea he had in the 70s Is that the physical model Or the P And the mathematical model Mapping the physical model Is not the same As we can discuss in physics So you can guess That in P There's things like modal claim That are not in the mathematical model There's maybe things about Qualitative properties That are not in the mathematical model On the other hand what they share It's structure It's maybe ambiguous how a mathematical structure Could fit in In what way a mathematical structure Could fit a physical structure And after that what is In the world physical structure Is probably Even more complicated to fit But what is interesting is that The problem of gauge In general relativity could come On the fact that it's A mathematical model So there's some stuff that is not there Like Modal claim that would change For example If you don't have A way like you Some kind of strong change notion So Becoming notion Contrary to difference notion Something that is not easy to represent Mathematically Of course you don't see it So it's not impossible That the screening is Even before symmetry There's no possibility To get a full time Full notion of time In the mathematical model Because it's mad And it's maybe Very difficult to see When you don't have this distinction Between two levels of modellization Which I think fits physics I'm not sure it fits other discipline But it fits very well physics That you have two levels Of modellization Or a sense which relies less On the mathematical parts To infer stuff But in theory or whatever But Other science that are less Structures I would expect To not have this distinction I would expect that if you have A science where there's a lot Of causal claim Of course you have mathematical language But you don't try to interpret Mathematical structure And in a very highly geometric Science like physics You all the time You interpret mathematical structure Not just Use mathematical language So you agree? I mean as I said When I was thinking about The change The change was different From the start of my physics What I was thinking about Mathematical way to present changes No static No cycle No physical change And so on That was why I wanted to have More continuous Contrary to your first argument It was coming from metaphysical concentration Now it's just Science modellization What do you mean When you were arguing That you should have not rich enough It's because you thought That in the scientific model Must be a metaphysical one Which is not necessary You could just have more richness Of things you can put in a model In p That you could put in n But now I should give the floor To the room Because we start late Question comments You can check online Yeah I have a question But I think it's very stupid I'm not sure I brought the surplus concept I know it's very well used I will use it also in practice But theoretically It seems very difficult to be fine The example you gave was Context number There is no such a thing It seems that when we use the surplus Concepts We try to have a mapping From theoretical objects And physical objects A kind of one-to-one mapping And I wonder if this Is a really good way to look at it I think it's stupid because I'm Pretty sure the answer you gave Was beyond that So that's why But I don't know I don't know Beyond that But I will give an example For instance, in quantum physics You have a bird space And you use it for Your tool But the equation by quantum physics Is not an actual a bird space At some point You have infinite integral And it doesn't match But it doesn't mean that A bird space has a surplus It's more like an analogy Quantum equations behave like In a space even if it doesn't Satisfy all Properties that need to be an actual bird So it's like Maybe more about Structure and analogy Than about mapping From theoretical objects and physical objects And I wonder if this Tof about What is it to be a surplus Who helps in a discussion Or if it was already contained No The boundary What is surplus and what is Properly relevant to the Presentation is always very fuzzy And always very hard to Define that's why we do interpretation Of theories The purpose of a theory to Interpret what is actually physically Playing a role in your A physical role in your A physical role in your And it's not just there to facilitate To have A way to do A mathematical thing with physical stuff But for your mapping And structure Point are not too sure I understood Because usually when you say that you're mapping stuff You're mapping structures to structures And the main Orthodoxy in terms of your physics is just that You have The theories are structures and the map to Structures in the world There is not much mapping To object directly That's why I said my map Would be stupid Because in one hand I know it's structure to structure On the other hand I feel like When we try to find what is a surplus We are like mapping objects To a symbol into the theory And that's why I don't know if they are just stupid Or if there is a kind of contradiction somewhere I'm not sure because In the case of symmetries What you're trying to map is Structural part of your Symmetries are structural parts And they are not object In the sense of Antities that are Just non-relational And just there They are mapping stuff to stuff Yeah, the first thing is the two examples again So the first is about Complex number So here we say Complex number doesn't exist So it seems to be one to one Maybe it was a non-linear And the other one Missile birth space I don't see where is the surplus Exactly What can be removed Exactly It's just that What we manipulate physically Are not the surplus space And we use the surplus space as a view of mind So I don't see Where would be the surplus I guess it depends on how you interpret quantum mechanics Because I know people who believe That maps to the world So I guess it's just In the helper space you reduce The phase To have the rate So there's already too much structure In the helper space that you have to get rid To get the quantum mechanics The idea is that there's another Representation that is reduced And it seems to be as good Because a priori you don't know You have a structure until You have another representation that seems better With less stuff Yeah, yeah So you can use a full helper space And suddenly you discover Yeah, but to have the good prediction I need to go to the race So I have to get rid of this phase That does not seem to do something Compared to other phase That seems to be very relevant And you get rid of it And you say, ah, it works So it was a surplus You didn't know before I mean the minimal Structure of model That applied to your number It's kind of related to On the autism stuff Even fundamentalism stuff In physics the more fundamental You have closer to the truth Your wings In the simplest Simplest you are Closer to the truth But in some way it's very independent About the question of What the physical Actual object are What do you mean by physical object No, I mean Since it's not a question The question of whether it's surplus Or not seems to be independent Of ontology I call it the ontological question You know It is true that Electron exists You know If you believe that If you are not a structuralist You believe that there are genuine objects That relate to the world The thing if you are a dispositionalist For example, you believe that Real stuff are objects With causal power In this position What you will relate to In your presentation Are the structures And the way are surplus Yeah, so But in that case It has several definitions So that's why I was confused So now I understand why I was confused I was working the very orthodox way To see structures mapping structures And doing everything with structures Which is the easiest thing to do Yeah, you are into the context of structure And so you have this definition Okay, we have another one Charles So I What I am afraid might be a mean question So you can just decide not to answer it You are absolutely allowed to say This is for the future of the project If you don't know yet But one thing that I am really interested in So I really like this idea That actually engaging And manipulating the world By means of the theory Is sort of forcing your hand To resolve these questions In ways that some of the people Who are dealing with this pure theoretical Perspective That they are not really seeing What it is that needs to be done there One thing that I think is really There is an interesting move That I think you are going to have to make And I wonder if you have thoughts About how you are going to do it So how can you generalize The account of an experiment Do you know yet? Because it seems like what you really love To be able to say If I am like reading the vibe of your talk And generalize the intervention in GR Looks like and every time you make one You have to make a call like this Which means you have to be engaging In this gauge fixing enterprise Which means like this is a really natural Way to interpret what is going on But like you got people to say What is an intervention In GR in the world In the right kind of way Do you have like even just like Speculative random thoughts I am not even asking for that This is a really cool move I just want to hear more Actually that's the thing that I talked about And he kind of crushed my spirit And I was like oh yeah I am going to do this experiment But you know in my case today It's very hard to Have a generalizable picture Of your study but If you look at the way People are active in physics right now They are very Non-specific Way to describe stuff So there is a massive man In the In Germany Who is doing physics And basically what he is doing Is looking at experiments And the same experiment Which is related to a Causality prediction And he is making Argument of the General form of experimentation The thing you do with the experimentations To induce stuff about Laws and how laws Should work in experiment after the experimental Setup Which is different Apparently from what How are you to think about law Usually But it's true that if you don't have Strong argument that what you are describing Is a transcendental Part of the experiment Just contextual Part I would say That's the part I want to end up with Because it's part of my thesis The way I see The future of my thesis I'm trying to show in a way That in experiments The modellative experiment Allows you to say that The change is a Commitive and time is a measure of change And the change is a model Concepts and it stems from The way of the experiments But that's the hardest part It's not just What you do in your corner But people are doing so much different stuff And actually that's the thing that I was kind of concerned About a few days ago Because I was looking at the experiment Of a GR And one of the reasons why you don't have Purchase evidence is because I thought there was a lot of cool stuff But in the end It's mostly just You have these two new laws in place They're very exact in them It's just the difference Of the frequency of the laser The gravitational wave has passed But there is no dynamic on site So that's A difficult part of the project That doesn't give you what you want Cool That's great, thanks I have an eye on it I have a general question You gave the example of general relativity If there is some other field in physics Where this distinction between Top-down and bottom-up For the light I haven't checked The thing that I've been thinking The thing that maybe For another PhD project I guess For experimental physics It could be quite interesting Because one of the biggest part But in talking about the other part But in talking about Quantum mechanics and quantum physics Is that you have this mister stuff So you don't know Exactly From the physics How your theory relates to the world And what experiments you're doing So if you look More at what is actually Done in experiments Maybe you would have a better understanding Of what is quantum mechanics And maybe you would constrain The interpretation of quantum mechanics From the bottom up It's purely speculative And is there a thing Between a major theory In general relativity And in quantum physics or not at all We have a theory of Measure But I don't know if it's It can be related The measurement problem Is not yet in general relativity Because we don't know the quantum theory However You're absolutely right That there's gauge symmetries Everywhere So if your analysis In general relativity Is blah blah blah It should be interesting to look If it works for other gauge symmetries Because all fundamental theories Are gauge Are gauge symmetries It's why it's strange That it's just a surface of structure It's a very very useful Surface of structure Even more than it's just useful It's in particle physics That way while you characterize Your objective of theories You're dealing with their characterizes Of the gauge But still we don't know what is the Rating theory If physics is making use of symmetries As a way to characterize objects in your theory You would expect that It's very strange if it's just a surface That's true Maybe it's a surface because What it really Presents perfectly It's so abstract that maybe Because we get this one to one map So we are thinking it should be Alné, merci de vos autres Alné, merci Nobody Put the risk to the motor I know you have an event But all the motor parts With the conservation of the gauge To symmetries it's very relevant Which are relatively important for everything else I think it's very interesting to see That it could be applied to other people The question is mostly about Physics but Could be about objectivity Variance, symmetry About the project instance If you have objections Critics I really prefer naive questions It's kind of stupid So I was wondering The whole time Top down Top up Where does it come from Why would you call theory up And experiments down What kind of order is there I mean In a practice you have both And they are not even I mean You constantly go from theory To experiments It's a process And scientific process And there is no Order I mean except maybe Like sociological hierarchy Where maybe People find the pure Physicists Higher up in society In the academic world I don't know What is for you, do you see an order At the start I was kind of Inclined to call them like a Platonician Platonizing approach You have a physical sphere At the bottom of the world And you take the hierarchy wherever you want The hierarchy is there And whichever party is more superior Is how you want The antique hierarchy The theory is up The sphere of Ever is up Physically, everything is up I guess But it's because the community Is obsessed by theory It's the supreme Way to get to the world So it's like an aesthetic Allusion I'm just More up That would probably be sociologically Supported Physicists would be like That seems right Just a question for verification Because I lost track there for a moment Can you Explain the Intermediary position You should be able to So what exactly is Their position Basically they are following up On the paper by Reading and Blown This idea of if you take the subsystem And the environment And you look at it from a Vertical point of view You don't see a gauge theory Because you can always set up The borders The frontiers of the system You can always set up your frontier To be smooth and then you put your gauge theory To extend to the whole system So the gauge is up Then you have What else in Greece in 2014 Who said that Maybe when you do that You should be more careful about how You neurologically patch Your subsystem to the world As a relation of the system There is always a fuzzy path In physics you never have a truly As a system so it's always kind of Weird to set up So the boundary is not just trivial It does relate to The account of how gauge symmetries Could have meaning And basically the idea is that The difference between Global symmetries having meaning And local symmetries having no meaning An empirical meaning The right way to see it Is the difference in interior symmetries So symmetries that are purely Defined on the subsystem And symmetries that are defined On the subsystem plus the The environment or the old stuff And then if you Look at it this way If you're purely inside the subsystem Of these entire symmetries You wouldn't see anything because It's the equivalent of the gauge theory But if you are looking at the broader pictures To set up your border is absolutely crucial Because if it's Your symmetry Preserves the boundary Then you could have Reational Not sure, I don't want to say Anything wrong but There is some ways In setting the boundaries To have gauge theories Have an empirical Contrapartible So however the pragmatical Aspects come from This idea of looking at The boundaries of systems In context to context situations To answer Peter I have a quote of Tim Muldlin The basic idea is simple Metaphysics in so far it is concerned With the natural world can do no better Than to reflect on physics Physical theories provide us Provide us with the best End all we have on what there is And the philosopher's Proper task is The interpretation and elucidation Of those theories But the practicality In particular, when choosing The fundamental opposite of one's ontology One must look to scientific practice Rather than to Philosophical prejudice The practice is there But it's theoretical practice And I could find one as well It's exactly the same And they all say the same And David Wallace was saying the same too But now it's a little bit more simple Because He refers to the point you were making Before I think between The mathematical representation Of your physical models That It's the mathematics that may be limited And some of the problems we see may come from The fact that Mathematics is just not reaching Of or not to try the kind of Language To try to represent Certain of those whose perfects like them Or are common I know but it's Philosophical The previous generation That were more sensible to experiments And It's purity or that's it They came after The divide Like with a cartridge and all the Eighty's guys The committee That was still the same stuff And people are just In different branches When I went to the PSP in Ghent I was talking about physics and metaphysics People were looking at me like Who are you? What are you doing here? And the reverse I went to the physics conference Two years ago And I was trying to say That's different stuff Same thing as what I'm doing here So it's very two different Very separate From what I've experienced That's not really a question About your talk It's about something you said Specifically I'm a complete outsider With this metaphysics It's made completely known For philosophy of physics You said something like Two physical states Are considered identical If they are empirically Distinguishable That's the way it's set up In the literature, let's give you an idea That's extremely strange from a philosophy Yes, yes It introduces an systemic Notion In an identity relation In physical states The idea usually is that The structures map to the world So if you can't distinguish Then your structure is not Mapping to one stuff Don't know what's happening It must be the same stuff But you're right It's a very strong empiricist position Yes Do they really think about it? Why do we need such a strong empiricist? What's meant to be empirically In this English Is meant to be empirically By who? By us With our present Observation techniques Or principle We are not always very careful with that When they are, they are saying that According to measurement apparatus That you use to test your theory That's the most careful Have seen literature so far Most of the time it's just Distinguishable by any ideal Measurement that you could think of I guess You could think of Another one Historic news Something that I've always I can think of a lot of things A lot of things Apart from the physics Most of the time when you read The papers and literature They are never explicitly sitting What they are doing by stuff Because they are doing the same stuff For 20 or 40 years I don't know why nobody talks about it Because it's so ingrained into Discussion Committee that people don't even think back on it So You just assume that everybody knows And everybody assume that somebody else knows You just continue And if science were able to speak for itself There would be no need For metaphysics at all I'm sure you can think of things So yeah, it's true that We are working against the current We've seen that But it's strange because this current As you said, was more diversified 40 years ago And people like hacking and cart-riding They were all discussing It's not sure how do you get The ontology from this thing Maybe you remember During the defense The first question I got from the Outside committee members But you're looking at things from the Experimental but you're not finding time From that You have to look at the theories So it's like It's not jargon Questions or comment For your time As usual Physics is so complicated That it's always better With the beer We will better understand later