Philosophy, physics, quantum field theory

0:00 Thank you. Just a couple of remarks before the local organization. We're in this room today. The room for the other three days will be different. And these remain largely unwritten about at all by philosophers. The role of anomalies, for example, has not been really studied or explored.

2:30 And of course there is an eternal theme of theory versus knowledge.

7:30 And this is the reason of my third topic today, which is precision data, the experimental data, creating a new class of arguments in how physicists think of their models.

10:00 It would be good for us, in its first major, to actually have new physics traces of a new, we see different kinds of ourselves to say something, you know, it becomes our next paradigm.

12:30 The most interesting part of Weidman's book, to write down in quantum, start with the symmetry is more or less synonymous, that start with the symmetric road.

17:30 Only if you say, I want to use the language of quantum field theory, then it's synonymous with starting with the symmetric road. So one reason why we have arrived at this situation where symmetry is the great building block of our vision of the world, So this is why we see the same asymmetry which could be put forward. Of course, you can just look at your effective theory as an approximation, as a working solution for shorter scales, for smaller scales.

25:00 So this is the so-called top-down approach. When you do know the big, so you know quantum chromodynamics, But for all practical purposes, you know, quantum thermodynamics is terribly complicated for calculating things, so you can have a chiral, effective chiral theory for much smaller scales with a chiral, chiral, right, I'm sorry. This is a top dog. Now we do something else with the effect, which means that defective field theory has become a tool for exploring, for exploration of new physics, which is not yet known. So we say, okay, here is the standard modal, and maybe there is some new physics somewhere else at 10 TeV. Whatever this new physics is, and we are completely ignorant about it, it has some effects at our scale, at the 1 TeV scale, in the form of an effect encoded in a bunch of operators at our scale.

27:30 So this is a kind of better-than-nothing approach, better than not knowing the full theory. Very complex. So there is no assumption of simplicity or beauty of this operators of high dimensions. It's very effective. Effective field theory. We have a tower of modals that decouple from each other. So can you say that whatever happens at one scale is decoupled from whatever happens at another scale? And there are very clear rules of correspondence between the two scales. So this debate started with some work by physicists in 1975 on a theorem which has proved that, so the theorem is about the exact age, and this was realized more or less lately, reductionism saying, much less the standard mode of the S-metric, that people were saying, okay, whatever happens there in the diffusion process, let's just look at the S-metrics approach, which only started as amplitudes, out to go incoming and outgoing amplitudes.

32:30 Now, if you want to reduce the amount of fine-tuning, so to go from a linear model, so instead of having a simple field content, here's how you do it.

37:30 In the minimal supersymmetric standard model, the fine-tuning is 1. Now, you want to gain one factor, which instead of a Higgs doublet, produces a Higgs quarter. Instead of four parameters in the Higgs center next to minimal with seven parameter modals are. So here's my modal. Well, it happens they are in competition of whose modal is going to be less fine. And this argument has been strangely debated about the entropic. So the entropic principle is more than this sounds to our chances. The basis of this fine. So here is a here is a bridge that we as probabilistic reasoning about a few.

42:30 It's happening today that people are evaluating the chances of various competing modals to be that winner, and the fine-tuning argument is more or less like betting on whether this modal or that modal. So this to me is a remarkable case of the probabilistic reasoning. The fine-tuning argument in itself, to me, is really an argument about the chances of this modal to finally survive the test and win something, a minimal extension of it.

57:30 Now, what I'm saying is that this variety of the naturalness of fine-tuning argument, the comparison argument between modus, has a flavor of this misuse of probabilistic reasoning as we know it from other cases of probabilistic reasoning. As if our 1% versus 5% versus 10%