The Eternal Doorman

From  Eron Woolf on Why Open Source is Failing : I posted something on the FUTO Zulip and thought I'd copy it here: Hello FUTO types, I was just rewatching the short talk by Matt Mikhailov and Vincent McKibbon on open hardware blues https://youtu.be/YLn4vnfchaE and the discussion with Daniel C. on the Rockchip bringup https://youtu.be/5klMcYG-AP0 and I thought I'd post another ten cents worth here. It's not only the directly connected hardware that's being locked down, it's the network infrastructure too. Looking at the crazy stuff that people have to do to "punch holes" so that they can send and receive data peer-to-peer without publicising an IP address. This is in a sense dual to the problem of locked-down hardware, and they actually exacerbate each other. There are security vulnerabilities in the proprietary hardware and firmware, and the networks will route hostile traffic to compromise the crappy router your ISP installed in your house, but that s...

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I got a bit lost there, ... but it does sound like there are a lot of things you can say about computability beyond just that "uncomputable functions exist".  It also sounds like Andy Pitts doesn't like modal logic.  I wonder what the quote was that he ended the talk with. I think it was something Jaap Van Oosten wrote somewhere. See  Basic subtoposes of the effective topos  (2013) by Sori Lee and Jaap van Oosten. Subscribe to  De KNAW . Here's a May 2022 talk on the countable reals. Subscribe to Topos Institute . After listening to these two talks last night I dreamed that someone was explaining to me how you could build computational circuits using a kind of "co-clocking". In this scheme the clock was an index into a type which was the successive ticks, and it meant that there was a notion of continuity in temporal evolution which was not the sort of thing Albert Einstein would have immediately understood. It was a really interesting dream! See David Albe...

I am having serious trouble listening to this stream of complete crap he's talking. I have only managed an hour so far, with a few breaks. My comment : 17:41 I can't take seriously statements like this one "The laws of Newtonian theory determine the complete physical condition of the world, given the complete physical condition of the world at some earlier time." This was an hypothetical argument made by Laplace and it's become something else entirely, solely through mindless repetition ever since. Nobody seriously believed you could learn anything about the world under this hypothesis, did they? It reduces knowledge to infinite initial information and time becomes meaningless, therefore knowledge cannot change. That's just not an interesting idea at all. No meaningful theory, complete or otherwise, can start from material and information without any understanding subject for whom that information is meaningful. Any such theory is vacuous. These vacuous theo...

Sounds like this heatwave in Europe and the UK would have been much easier to handle if there were a lot more beavers.  Subscribe to Hope .

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My comment : There is this 2000 paper "Information theory explanation of the fluctuation theorem, maximum entropy production and self-organized criticality in non-equilibrium stationary states" by Roderick C. Dewar which is really insightful, I think, but I found it quite hard to understand at first. He deals with the problem of defining what are the parameters of the macroscopic model without referring to any details of the microscopic system: so the reproducible macroscopic behaviour is described entirely in terms of expectation values on the underlying distributions in phase space.  The problem is that in a weather forecast it is not even clear what temperature/humidity could mean at the level of even a 10x10x10cm cube of air. So the idea of the accuracy of the measurements is kind of redundant since we have no way to even say what accuracy means!  See  Lyapunov Stability in Dynamical Systems  and  these other posts of mine .   Subscribe to Charlotte Mo...

The muppets at 5:24 : Subscribe to  Oz Harms . See George Ellis and Ard Louis on top-down causation in  Why is Physics So Difficult? It seems like real life only because we know what it is supposed to be like:  And we know it ends well, ... Subscribe to Secondhand Movie Company . This post is a sequel to  About Logic - Is Mathematics a Story? What is a dependent type? What is a judgement? There's one missing, isn't there? What is a dependent judgement then? It's a judgement about a judgement, because it includes the turnstile. So how do you construct one? 21:06 . All these judgements are hypothetical : they depend upon some actual construction of the contexts Г in which they are valid, just like real life .  11:15 .   See the full list of talks here .  The two texts referred to ( 17:10 ): The HoTT Book, a.k.a. Homotopy type theory: Univalent foundations of mathematics . Introduction to Homotopy Type Theory by Egbert Rijke. Subscribe to  EPIT Spri...

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It's an interesting discussion. Get their book via  this stripe link .  Some comments: 1:28:06  On bodies and their actions. Someone mentioned batteries storing electrons and Shilo compared that idea to the one that ovens store heat. Ovens and batteries are things physicists actually used to abstract concepts like electric charge and thermal energy and their relationships like the heating effect of resistance to charge flow. All of that phenomenological physics was done without positing any fundamental carriers of heat or charge. In terms of bodies and their actions you can explain an oven in terms of a cold body being put in contact with a hot one and the action being an increase of temperature of the cold body and a decrease in that of the hot one. One can then relate temperature and electric current using thermocouples, say. Then one can abstract the notion of a current source at a certain potential and call that body a chemical battery (copper and zinc electrodes in a...

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They're threatening to do this weekly, ... My comment :  Looking forward to the Dana Scott interview! Maybe there's not time to do this before then, but I would like to hear a discussion about the different views people have about models. I sometimes think that Computer scientists look for models in the zoo of mathematical theories, because they feel like this the only possible source of their legitimacy: they say something like "Well, this type system is sound because if it wasn't then ZFC would be inconsistent and you would have much bigger things to worry about than the soundness of my little type system!" But then serious mathematicians who have Fields medals come along and say "Well actually, I have these proofs that I've done in Higher Homotopy theory and I seriously doubt anyone has checked them as carefully as I did, and I am not sure that I haven't made a mistake somewhere, ..." and then they find a type system that a computer scientist ...

See  Breaking through the normalization barrier: a self-interpreter for f-omega  (POPL 2016) by Matt Brown and Jens Palsberg. Here's his earlier  video about System-F .  Subscribe to Computable Secrets . Jeremy Gibbons on his book Functional Programming Patterns   See his piece How Design Co-programs .  Why is so hard to get anyone to talk about the dual notion which is data representation by processes? If data determines algorithms, then algorithms can equally well determine data. And if those algorithms are distributed computations then it makes the data they represent very hard to alter. If you ask a computer scientists they might just say "Well, that's because they're not isomorphic." But that doesn't matter: it just means that codata can represent so-called uncomputable functions, which can actually be used in practical applications such as forward key-generation. Some physicists also don't seem to want to think about what data actually is. See  J...

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1:06:18 He's a Taoist, ... I suppose that shouldn't be a surprise. Subscribe to European Mathematical Society . 

Here's the whole blackboard: I had to time-travel to get that picture, so please look at it! My comment : This is great material you're presenting, but the tech you're using is several steps back from a chalkboard or a pen and a piece of paper. I need to see what's been written to be able to refer back to definitions when you use them later, and I can't do that without rewinding the video. You've serialised a manifold isomorphic to R^3!  I have a problem with the bit right at the beginning though. It's not clear to me what is S^2 and what is Q. Clearly the points q_1 and q_2 are on S^2, and q then seems to be path of points on S^2 and t_1 and t_2 are on the real line? So the path function q picks out for each t in the interval [t_1,t_2] a single point in the general configuration space Q. So what we are trying to ascertain is whether there is some sort of canonical representation of the dynamics of the system that fixes the trajectories it can take through ...

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My comment : 2:30 If we knew the initial conditions perfectly, .... But but but, .... you have a model, right. Your model has some representation of state, and some set of functions mapping state changes as a function of time. So the "initial conditions" you are referring to are the initial states as represented in your model. Surely yes, because even if your model was using states of individual atoms then it would only represent them with some finite amount of data, so to a limited resolution. So your model is always representing not actual physical states, but statistical distributions of physical states. So there is no real way I can understand what knowing initial conditions perfectly could mean. Even if the model was subatomic, there is no notion of perfect knowledge of the state, because, even if it exists, it's hidden until you measure it. The reason I am making a fuss about this is that it is getting the notion of determinism wrong. There is an idea around that d...

I'm sure this will be great Scott. Ask Bertrand Russell if you don't believe me. See the centenary talk Scott gave on Strachey  and also Scott, D. Some Reflections on Strachey and His Work . Higher-Order and Symbolic Computation 13, 103–114 (2000). https://doi.org/10.1023/A:1010018211714  and Toward a Mathematical Semantics for Computer Languages (1971) by Scott and Strachey. 2:03 From Scott's Strachey centenary talk: Let us now return to λ-calculus and Strachey’s use of it. Christopher told me once that Roger Penrose (now Sir Roger!) suggested to him that he ought to look into using the λ-calculus for the kind of function definitions he wanted to do. At this moment I cannot track down or verify the story. (Perhaps people in Oxford might ask Penrose personally about this?) See  Curt Jaimungal Talking With Roger Penrose  and the reference Penrose made to S. W. P. Steen's graduate course in Mathematical Logic. In 1973 Steen published a book  Mathematical Logic ...

That's fun. He doesn't mention it, but I think they're using Topos theory behind the scenes. If they're not then they probably should be! See  Richard Southwell Being Norman Wildberger . On that early Universe/Scattering Amplitudes duality, see  The Category Enriched over the Category of Finite Sets, The Finitely Triangulated Manifold and the Magnitude of a Finite Category . See Another Two Talks on Cosmology and  Clark Barwick on Factorisation Spaces and "doing physics" in Spec ℤ .  Subscribe to Institute for Advanced Study .

See the full interview here:  About Logic with Andrej Bauer  and this discussion at 40:14 . You can support Deniz by helping with production costs via  https://buymeacoffee.com/aboutlogic . My comment : The good old completeness theorem is my favourite theorem! Can you  and Thorsten interview Paul Taylor some time and ask him why they wrote Proofs and Types in such a bizarre way. Was it to drive people insane if they were stupid enough to try to understand logic and computation? Subscribe to About Logic . My comment : I am wondering whether I am the only person in this subset of people who understand some part of this video, ... Subscribe to Sheafification of G .  See Dana Scott's Stochastic Lambda Calculus: an Extended Abstract  and Lattices Everywhere . This whole way of doing topos theory just doesn't seem right to me. If it's all based on constructive mathematics then why can't it all be described in one language? These people keep inventing new langu...

John Baez interview with Latham Boyle Notice that he hardly ever mentions the theory and actual observations, just the deductions that they have made from them ( 2:47 ). To me this sounds like a state of almost complete ignorance. Sure, it's simple enough, but why is this interesting? Is it because he thinks he has shown that we don't need to assume anything special about the initial state of the Universe, and that it spontaneously produces all the structure we could ever abstract from observations of its present state? 14:10 When you look at the cosmic microwave background now you find it is far from scale-invariant because of the gravitational clumping that's been going on since. Personally I think this just means that it was all so long ago that not even God knows anything about it. See this talk on coupled oscillators as associative memories for compositional inference . Subscribe to John Baez . Mike McCulloch on what sort of things would happen if you found that some ...

41:31 That point of perspectivity is invisible from the perspective of the camera!   See Coxeter's Projective Geometry on the Internet Archive .  Subscribe to  Richard Southwell . This is a placeholder for Norman's upcoming video on polynomial functors in terms of slice categories and adjunctions or something, ...  Well, Norman didn't show up, so I found this talk by Simon Willerton on the Categorical notion behind the Legendre-Fenchel Transform. 1:06:16 Interesting question about the Cauchy completion of the rationals. It reminded me of the theorem of Kronecker for some reason. See Lawvere's 1984 paper  State Categories, Closed Categories and the Existence of Semi-continuous Entropy Functions . I think that if you just consider a finite complete lattice then you will get most of this structure (of the Legendre-Fenchel transform) in a topological space. Then maybe you can extend it to an infinite lattice using some model in projective geometry. So one s...