Curt Jaimungal Interviews Gabriele Carcassi

46:24 Let me tell you what I think Quantum Mechanics is, ... This is where physics is upside-down. A physical system is defined by boundary conditions and these are macroscopic, if anything is to be observable by human beings. It is the boundary conditions which determine the measurable variables, not some idealised notion of the internal 'objective state' of that system.

1:34:15 Interesting discussion about non-additive measures of entropy in Quantum Mechanics.

1:47:51 What counts as a measurement? This is hard to say because in quantum mechanics individual measurements do not actually occur. When they do they have no statistical significance. It is only in the aggregate as a whole that the expectation values predicted by the theory can be verified.

1:59:33 He thinks of it as an engineering project. It's not about doing new physics, it's about finding the right connections between disciplines. There is an issue here though, because our knowledge develops in between levels of description, so the engineering project is one that can never end. So I think he's wrong when he says "There must be a physical justification why it works". The justification is more formal than physical. Think of Neil Turok and his idea of a Mirror Universe "before the Big Bang" (see ). What really needs to change is the culture of the subject. See Curt Jaimungal Talking With Roger Penrose.

Carcassi has a YouTube channel and a proper job:

I am a researcher at the University of Michigan and I work on a project that aims to rederive the basic laws of physics from a handful of physical ideas (see http://assumptionsofphysics.org). In some videos I try to condense the insights I gain in a way that is (hopefully) accessible to beginner students in engineering, math and physics. In other, I present the latest advances of our research. [See also the YouTube channel Assumptions of Physics]

If you like the videos, you may also enjoy my blog at: http://sufficientlywise.org/

Here's a video he made after a visit to The Perimiter Institute

He says you have to talk to Julian Barbour about everything to do with Mach!

Here's his set of videos on Quantum Essentials:

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This afternoon I was thinking about Thermodynamics:

See Joan-Emma Shea - The Link Between Proteins, Alzheimer’s and Parkinson’s Diseases.

Spike Milligan's invitation to the Cambridge Union:

What sort of crackpot am I? A bit of a mixture of all of them, I think.

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Here's a nice story about collaboration in foundational research. And the background is a collaboration where a group of mathematicians managed to prove the theorem ⊦ FALSE. This talk was given March 26, 2014. Voevodsky died on September 30, 2017.

42:13 See Science Direct on Groupoids. I'm not sure why Voevodsky thought that this meant Categories are not a suitable foundation for mathematics. Maybe he'd spent too long in "The Next Dimension"? The construction I showed to Ebbe Elsborg on February 14, 2010 was a kind of very general congruence relation on groupoids. All I did was take the most basic notion of a Category and a functor and see what I could construct predicatively using the syntax I had described in On Tarski's Semantic Definition of Truth "Convention T". Ebbe said I should do it all in set theory. I looked at that and pointed out to him that set theory has this weird issue with inner models which determine the sorts of theorems you can prove, and that Larry Paulson was the expert in this. See Paulson's CADE-12 paper A fixedpoint approach to implementing (Co)inductive definitions (1994). Then a month later Lucy Milner died, then Robin Milner died a few days after that. It was Robin Milner who introduced me to Ebbe Elsborg, when I told him I was going to live in Bolivia. Ebbe Elsborg did his PhD at DIKU under Mads Tofte. See Jane Street Capital for more on the GC. I think the Grothendieck Construction was a secret that was exploited by National Intelligence Agencies (see PhD War Stories Time) and was considered too powerful to let it become widely-understood (see e.g. Lattices Everywhere), and that my brief article (On Tarski's Semantic Definition of Truth "Convention T") was seen by some as doing exactly that, and that people were murdered as a result of it. But I would be more than happy if someone could prove me wrong.

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The reason this construction works is very straight-forward and obvious and it applies to physics just as much as it does to mathematics, and it goes back to Poincaré's 1908 address to the ICM (see Jeremy Gray's Poincaré Replies to Hilbert: On the Future of Mathematics; September 2012 The Mathematical Intelligencer 34(3)):