Image generation through coupled oscillation

The legacy of string theory, a generation of physicists content to play with math

Whoops! A transformer doesn't understand F = ma

Correct! Just as a reminder: this is what a Transformer found after looking at 10M solar systems https://t.co/cz6MpG2Qtq pic.twitter.com/OozXPKYatb

— Martin Bauer (@martinmbauer) September 10, 2025

Will AI Save Physics? Probably not.

Hossenfelder is skeptical. 1) It's unlikely that AI will achieve breakthroughs by analyzing data. Why? because we don't have much data on the phenomena of greatest interest. 2) Perhaps there's something to be done in analyzing the published literature, but she's skeptical about that. Why? Because the current literature, though huge, consists mostly of recycling the same ideas (the ones that don't work). 3) Then there's theory development. Current systems aren't good at it because they need to be trained on something. You mean the current crop of "junk" theories? And future AI? Perhaps. But we need something better than logical AI.

A possible axiomatic derivation for the “arrow of time”

YouTube:

David Hilbert’s Sixth Problem is 125 years old and asks for an axiomatic foundation of physics. A good place to start with this, said Hilbert, would be fluid dynamics – physicists should be able to prove that our fluid dynamics equations are rooted in how we understand atoms behave when they bump into each other. This would also explain the origin of irreversibility in our lives, or the “arrow of time” as physicists like to say. Over a century later, mathematicians have made a major breakthrough in this arena. Let’s take a look.

That is, we may have an explicit way of showing how irreversible behavior can emerge from underlying reversible laws.

Ole Rømer estimated the speed of light in 1676. He was the first.

See this clip featuring Neil deGrasse Tyson. He begins by telling us that Galileo was the first one to attempt to measure the speed of light. He only concluded that light was either infinitely fast or it was faster than we could measure.

He then mentions a Danish astronomer named Ole Rømer. Wikipedia:

Rømer's determination of the speed of light was the demonstration in 1676 that light has an apprehensible, measurable speed and so does not travel instantaneously. The discovery is usually attributed to Danish astronomer Ole Rømer,[note 1] who was working at the Royal Observatory in Paris at the time.

By timing the eclipses of Jupiter's moon Io, Rømer estimated that light would take about 22 minutes to travel a distance equal to the diameter of Earth's orbit around the Sun.[1] Using modern orbits, this would imply a speed of light of 226,663 kilometres per second,[2] 24.4% lower than the true value of 299,792 km/s.[3] In his calculations Rømer used the idea and observations that the apparent time between eclipses would be greater while the Earth is moving further from Jupiter and lesser while moving closer.

Rømer's theory was controversial at the time that he announced it and he never convinced the director of the Paris Observatory, Giovanni Domenico Cassini, to fully accept it. However, it quickly gained support among other natural philosophers of the period such as Christiaan Huygens and Isaac Newton. It was finally confirmed nearly two decades after Rømer's death, with the explanation in 1729 of stellar aberration by the English astronomer James Bradley.

Remarkable. It shows the value of having the right conceptual ontology for thinking about the world. Which ontology are we talking about? I assume it's the one shared by Galileo, Huygens, Newton, and Rømer, among others. What aspect of this ontology allowed for, made possible, these observations? Surely it is bound up in the mechanical properties of natural phenomena. I'm guessing (I've not thought it through) that it would have been impossible to state these mechanical properties without decimal-point arithmetic. This is Rank 3 in the account of cultural evolution that David Hays and I elaborated in a series of papers (along with Hays's book on technology) in the 1990s.

Hossenfelder: Wolfram's research program seems healthy (after all). Perhaps it can work.

From the webpage:

Mathematician and Computer Scientist Stephen Wolfram wants to do no less than revolutionizing physics. He wants to do it with computer code that gives rise to all the fundamental laws of nature that we know and like -- and maybe more. Unfortunately, Einstein’s theories of general relativity inherently clash with how computers work. And yet, he and his team might have found a clever way around this problem.

Hossenfelder: The 2024 Nobel Prize in Physics Did Not Go To Physics -- This Physicist is very surprised

Hossenfelder comments: "A quick comment on the 2024 Nobel Prize in physics which was awarded for the basis of neural networks and artificial intelligence. Well deserved, but is it physics?" She also wonders if this does't reflect (what she regards as) the dismal state of current work in the foundations of physics and points out that physicists have been using neural networks for years as tools.

Herbert Simon won the Nobel Prize in Economics in 1978 for "for his pioneering research into the decision-making process within economic organizations." The Nobel Committee did not mention his work in Artificial Intelligence. But would he have gotten the prize without that work? 

* * * * *

Gary Marcus has an interesting post on the physics Nobel, for AI, and the chemistry as well: Two Nobel Prizes for AI, and Two Paths Forward:

Let’s start with Hinton’s award, which has led a bunch of people to scratch their head. He has absolutely been a leading figure in the machine learning field for decades, original, and, to his credit, persistent even when his line of research was out of favor. Nobody could doubt that he has made major contributions. But the citation seems to indicate that he won it for inventing back-propagation, but, well, he didn’t.

He goes on spell out a more detailed history of early work in neural nets, citing remarks by Steven Grossberg and Jürgen Schmidhuber.

Emergence

𝗘𝗺𝗲𝗿𝗴𝗲𝗻𝗰𝗲, 𝘄𝗵𝗮𝘁 𝗶𝗻 𝘁𝗵𝗲 𝘄𝗼𝗿𝗹𝗱 𝗶𝘀 𝗶𝘁??
It would be cool to have a discussion on this one, who knows @seanmcarroll might even join??? https://t.co/VCuoabW8zf pic.twitter.com/Uhb9gD3Fz8

— Luiz Pessoa (@PessoaBrain) September 18, 2024

Emergence and computation [separation and mixing of scales | lumpability]

Fernando E. Rosas, Bernhard C. Geiger, Andrea I Luppi, Anil K. Seth, Daniel Polani, Michael Gastpar, Pedro A.M. Mediano, Software in the natural world: A computational approach to hierarchical emergence, arXiv:2402.09090v2

Abstract: Understanding the functional architecture of complex systems is crucial to illuminate their inner workings and enable effective methods for their prediction and control. Recent advances have introduced tools to characterise emergent macroscopic levels; however, while these approaches are successful in identifying when emergence takes place, they are limited in the extent they can determine how it does. Here we address this limitation by developing a computational approach to emergence, which characterises macroscopic processes in terms of their computational capabilities. Concretely, we articulate a view on emergence based on how software works, which is rooted on a mathematical formalism that articulates how macroscopic processes can express self-contained informational, interventional, and computational properties. This framework establishes a hierarchy of nested self-contained processes that determines what computations take place at what level, which in turn delineates the functional architecture of a complex system. This approach is illustrated on paradigmatic models from the statistical physics and computational neuroscience literature, which are shown to exhibit macroscopic processes that are akin to software in human-engineered systems. Overall, this framework enables a deeper understanding of the multi-level structure of complex systems, revealing specific ways in which they can be efficiently simulated, predicted, and controlled.

A physics that explains 'everything' while evading the temptation of being a Grand Unified Theory?

The (Simple) Theory That Explains Everything | Neil Turok

56,115 views Apr 23, 2024 Theories of Everything with Curt Jaimungal

Physicist Neil Turok, recipient of the James Clerk Maxwell Medal and Prize, and the John Torrence Tate Award for International Leadership in Physics, joins Curt Jaimungal and Theories of Everything to discuss his new hypothesis regarding the origins of the universe. Building on Stephen Hawking's geometrical model, Turok proposes a theoretical approach that avoids the singularity at the Big Bang by suggesting a minimal, mirror universe scenario without requiring inflation.

Consider signing up for TOEmail at https://www.curtjaimungal.org

Timestamps:
00:00 - The Big Bang Is A Mirror
15:40 - Minimalism In Physics
28:28 - Neil’s Theory “Minimalism SM LCDM”
31:20 - Fields Vs. Particles
49:15 - The Arrow Of Time (Bolztmann)
55:44 - Black Hole Singularity Vs. Big Bang Singularity
01:09:21 - Numerology And The Number 36
01:19:26 - Neil’s Theory Solves EVERYTHING
01:23:32 - What Do Other Scientists Think?
01:36:28 - The Dual Universe
01:44:14 - Predictions From Neil’s Theory
01:48:28 - What Motivates Neil?
01:52:20 - Wave Function Of The Universe
01:57:20 - Support TOE

Entropy and Self-Organization on the Table Top [Emergence]

I'm bumping this to the top of the queue: 1) on general principle, and 2)  because I was going to include some of this material in a paper that goes up on 3 Quarks Daily, but then I decided not to use it. So here it goes. Moreover (3), it's a good antidote to the all too frequent and casual use of the concept of "emergence," which more often than not is used as a sophisticated synonym for "magic." We don't really know what's going on so we'll call it emergence. Well, in this case, the appearance of convection cells, we know what's happening:

The tumbler was sitting on a window sill during the morning and mid-day on a sunny day. Sunlight came through the window and heated the water, just a bit. But the black carbon particles in the ink absorbed energy faster than the water molecules, making them warmer than the water in which they were immersed. That’s what supported the formation of those convection cells, which began dissipating within an hour after they had formed. No violation of the Second Law of Thermodynamics. You can download this discussion as a PDF from this link.

With a Note on What to do When You are Fascinated by Technical Concepts but Lack the Math: Call the Plumber!

Matter is not given. In the present-day view it has to be constructed out of a more fundamental concept in terms of quantum fields. In this construction of matter, thermodynamic concepts (irreversibility, entropy) have a role to play. 

–Ilya Prigogine and Isabelle Stengers, Order Out of Chaos, 1984

I’ve been thinking a lot about entropy lately.

It is, of course, one of the foundational concepts of modern thought, haunting our dreams with the prospect of the universe grinding to a halt in heat death, but also animating our hope of understanding how life arose in the universe. In a Latourian context one might even speculate that entropy is the concept that, more than any other (except perhaps biological evolution, with which it has become richly intertwined), gives the lie to the Modern’s conceit that they are here and nature is somewhere over there, separated from one another by a sharp line of clear and distinct ideas. For the concept of entropy, unlike relativity and quantum mechanics, has arisen from deep within the world of classical physics.

According to the Wikipedia the term was coined in 1865 by Rudolf Clausius, but the work leading to the concept originated earlier in the century with the research of Lazare Carnot, a mathematician whose

1803 paper Fundamental Principles of Equilibrium and Movement proposed that in any machine the accelerations and shocks of the moving parts represent losses of moment of activity. In other words, in any natural process there exists an inherent tendency towards the dissipation of useful energy. Building on this work, in 1824 Lazare's son Sadi Carnot published Reflections on the Motive Power of Fire which posited that in all heat-engines whenever "caloric", or what is now known as heat, falls through a temperature difference, work or motive power can be produced from the actions of the "fall of caloric" between a hot and cold body.

There you have it, the machine, a mechanical device with moving parts. We have Newtonian mechanics with its three laws of motion and the grand suggestion that the universe works like a clock, a vast device of many parts all ticking away in perfect order, except when they don’t. And there’s La Mettrie’s 1748 treatise, Man a Machine.

Oh! how easy our intellectual life would have become if only the universe were nothing but a clock and we but little tick-tocks within it.

But it is not, nor are we. The mechanistic vision ground to a halt in the analysis of fire and we became but especially clever monkeys through Darwin’s elucidation of a pattern he traced though the geological, paleontological, botanical and zoological records.

Chasing Molecules

Though my interest in entropy is long-standing, my recent thoughts have been occasioned by various and numerous remarks the philosopher Levi Bryant has made at Larval Subjects, his blog. The post Entropy and Me is a representative example. Or, consider this passage from his book, The Democracy of Objects (pp. 227-228):

Entropy refers to the degree of disorder within a system. Suppose you have a tightly closed glass box and somehow introduce a gas into it. During the initial phases following the introduction of the gas into the system, the gas will be characterized by a high degree of order or a low degree of entropy. This is so because the particles of gas will be localized in one or the other region of the box. However, as time passes, the degree of disorder and entropy within the system will increase as the gas becomes evenly distributed throughout the box. In this respect, entropy is a measure of probability. If the earlier phases of the gas distribution indicate a lower degree of entropy than the later stages, then this is because in the earlier phases there is a lower degree of probability that the gas will be localized in any one place in the box. As time passes, the probability of finding gas particles located evenly throughout the box increases and we subsequently conclude that the degree of entropy has increased.

This seemed a bit, well, “off” to me. For one thing Bryant doesn’t say just how the gas gets introduced into the box. Surely he doesn’t mean that it gets magically whisked there through a Star Trekkian transporter. But what DOES he mean?

Well, he probably meant something like poking a small hole somewhere in the box and letting the air rush in. So that’s what I did. Not physically, of course, as I have no convenient source of high-vacuum boxes, but in my imagination.

I began imagining lots and lots of tiny tiny air molecules going in through the hole. Does that first cohort march in formation like a highly trained marching band or drill team, or do they twist and tumble every which way, pushed by the molecules behind them, and those behind them, and so forth? How fast do they move? Who’s the first to make it to the other side? And how do you measure their positions?

It seemed reasonable to think, as Bryant more or less stated (except, remember, he said nothing about a hole), that they’d be bunched up near the hole at the beginning and that, at the end, they’d be scattered evenly throughout the box. But how’d they get from one state to the other? Getting from New Jersey to New York is easy, there’s the Holland Tunnel, the Verrazano-Narrows Bridge, and so forth. But the kind of states we’re talking about aren’t geographical regions and moving from one to the other is not like getting in a car, turning the key (or pushing the button) and driving away.

And, by the way, just what does “evenly” mean? It might mean that they’re at the vertices of a cubic lattice, or some other regular structure, but I suspect that that’s not what Bryant meant. If not THAT, though, then just what? Perhaps he was, in his imagination, dividing the box into lots of tiny cubes. We then count the number of molecules in each cube. It doesn’t matter just where they are in the cube, just so they’re inside it. Some place. And when we’ve done our count we find that there’s approximately the same number in each imaginary cube.

Now we’re getting somewhere, says I to myself, we’re making progress.

But no, we’re not, we’re just getting deeper and deeper into the quicksand. What’s the size of our imaginary cubes? Does it matter? And those molecules, they’re moving, right, always moving. Since we can’t possibly examine all these imaginary cubes at one time, but have to look at one after another, how do we keep those molecules inside their proper imaginary cubes? And, since the little critters are identical to one another, how can we be sure that some of them aren’t sneaking about from cube to cube just to mess up our count?

Now, you might say, this is all nonsense, this stuff about imaginary cubes and pesky molecules who are unwilling to sit still for the count. Well, yes, you’re right, it’s nonsense in a way. But, if Bryant’s talk about order and probability is to have any substantive meaning, then we really do have to have some way of locating and counting those molecules. We need some way of taking measurements and my imaginings, some of them anyhow, are aimed at the informal notion of evenness. If we're going to measure it, well, what does it mean? Without measurements we’re just talking gibberish.

Still, it’s clear that something isn’t working. My thinking was at an impasse, that’s clear. I’m in over my head. What to do?

Call the Plumber

My plumber is Tim Perper. Though he’s not a plumber, he’s not even a physicist. He was trained as a molecular biologist and geneticist, worked in industry for a bit, worked in academia for a bit, and then decided that he was really more interested in human courtship than in complex molecules. So he spent a couple years hanging out in bars, night clubs, church socials and such and wrote down what he saw people doing—all courtesy of the Guggenheim Foundation. He wrote that work up in a book, Sex Signals (1985), that work and, of course, a lot more, including Ovid and Durkheim.

Physics for little girls

Give her physics! Physics for all the little girls!

From "The Silver Chair" by C.S. Lewis, 1953 pic.twitter.com/ezENmu7Uf9

— Sabine Hossenfelder (@skdh) January 4, 2024

 

Tiby Kantrowitz's booth at Maker Faire 2014 in Queens

Sabine on Complexity

The Biggest Gap in Science: Complexity

00:00 Intro
00:28 What is complexity?
02:57 Measures for complexity
07:41 Properties of complex systems
13:33 Recent Approaches
16:20 Stay up-to-date with Ground News 

Bonus: Check out my Primer on Self-Organization.

Sabine Hossenfelder on the mess that is particle physics

About the video:

Why do particle physicists constantly make wrong predictions? In this video, I explain the history and status of the problem.

My list with "good" and "bad" problems in the foundations of physics is here:

http://backreaction.blogspot.com/2019/01/good-problems-in-foundations-of-physics.html

00:00 Intro
00:30 The History of the Problem
08:29 The Cause of the Problem
14:52 Common Objections and Answers
19:37 What Will Happen?
20:04 Learn Physics on Brilliant

Can Physics Be Too Speculative? An Honest Opinion [Sabine Hossenfelder]

From the YouTube description:

I was asked to write an article addressing the question whether some research in physics has become too speculative. I did as I was asked, and all seemed fine, until someone on the editorial board of the magazine decided that physicists would be too upset about what I wrote.

The exact text of my opinion piece was too long to copy it here, so I put it up on my blog: http://backreaction.blogspot.com/2021/07/can-physics-be-too-speculative.html

You can support me on Patreon: https://www.patreon.com/Sabine

0:00 Intro
1:05 Progressive of Degenerative?
3:23 Dark Matter
4:39 Fifth Forces
5:17 String Theory
6:22 Multiverses
6:55 Alien Technology
8:56 Sponsor Message

Active Matter

"I consider the Organism, or natural Machine, a machine in which each part is a machine."
- #Leibniz

🦠 Energy → Work

"Active matter *employs* control, either internally [e.g., embryogenesis] or externally [e.g., with sheepdogs]."
- @SurajShankar92 pic.twitter.com/4l2NAG3F7C

— Santa Fe Institute (@sfiscience) October 5, 2022

Sabine Hossenfelder on reductionism [computers (& implementation)]

Robert Lawrence Kuhn is hosting Sabine Hossenfelder is a discussion of her new book, Existential Physics: A Scientist’s Guide to Life’s Biggest Questions. Some 20 minutes in or so Kuhn and Hossenfelder are talking about reductionism, the idea that we seem to be able to explain the properties and actions of things at some scale by invoking objects and actions at a smaller scale. Hossenfelder has expressed the idea that perhaps there are limits to this process and that, at this point, our problems aren't at the smallest scale, but rather (c. 22:44)

maybe what our problems are trying to tell us is that this ontological reductionism has reached its limits, so maybe we should not try to figure out if elementary particles are made of strings. Maybe our problem is describing how big objects come about.

Kuhn brings up the question of whether or not (c. 23:21) "there are ontologically fundamental laws that exist in large constituents that are not reduced ... to the actions of small particles." This leads him to a distinction between strong emergence (macro can't be explained in terms of the micro) and weak emergence. She rejects strong emergence (we don't have any cases) but doesn't think we need strong emergence to "have fundamental laws at large distances." She then refers to her interview with David Deutsch which eventually leads to (c. 27:23):

So, you have your microscopic description and now imagine you're able to do your derivation of the macro level, so this is weak emergence. But now you have a theory which is completely useless; it's just too difficult. And so you reformulate it in other assumptions, and those assumptions use ingredients from the macroscopic level and the no longer rely on the underlying microscopic structures. So there's no disagreement.

I think the other example that David Deutsch used is the existence of a universal computer. And that's not something which you can express in laws of the microscopic constituents, elementary particles or something. It's a property that comes out at the macro level. And it doesn't disagree with the existence of laws on the microscopic scale. And if you were really really good maybe you could start with something like string theory and then prove it would give rise to a universal computer, but it doesn't really make a lot of practical sense to try to use this kind of calculation. So you would use a theory on the macroscopic level that postulates well, universal computers exist and that's something that you can work with.

That's something I've discussed in terms of implementation, e.g. in Fecundity and Implementation in a Complex Universe, Is software a kind of mathematics?, and Physical constraints on computing, process and memory, Part 1 [LeCun].

Dark matter isn't what it used to be [three cheers for condensed matter]

Have you seen this? https://t.co/ZkfoNH3LMY

— Ian Robinson (@IanRobinson) August 1, 2022

Topics in the video:

0:00 Intro
0:23 What is dark matter?
2:22 Evidence for dark matter
5:11 Evidence against dark matter
7:25 If not dark matter, then what?
9:43 Why we haven't made progress

At 9:32 in the video:

The difference is the behavior of these fields or particles. It's the behavior that changes from the scales of galaxies to clusters to filaments and to the early universe. So what we need is a kind of phase transition that explains why and under which circumstances the behavior of these additional fields, or particles, changes, so that we need two different sets of equations. And once you look at it this way, it's obvious why we have not made progress on the question of what dark matter is for such a long time.

There're just the wrong people working on it. It's not a problem you can solve with particle physics and general relativity. It's a problem for condensed matter physics. That's the physics of gases, fluids, and solids and so on.

So, the conclusion that I have arrived at is the distinction between dark matter and modified gravity is a false dichotomy. The answer isn't either – or, it's both. The question is just how to combine them.

Anything beyond the Higgs? Is collider physics over?

Adrian Cho, Ten years after the Higgs, physicists face the nightmare of finding nothing else, Science, 13 June 2022.

Before the 27-kilometer-long ring-shaped LHC started to take data in 2010, physicists fretted that it might produce the Higgs and nothing else, leaving no clue to what lies beyond the standard model. So far, that nightmare scenario is coming true. “It’s a bit disappointing,” allows Barry Barish, a physicist at the California Institute of Technology. “I thought we would discover supersymmetry,” the leading extension of the standard model.

It’s too early to despair, many physicists say. After 3 years of upgrades, the LHC is now powering up for the third of five planned runs, and some new particle could emerge in the billions of proton-proton collisions it will produce every second. In fact, the LHC should run for another 16 years, and with further upgrades should collect 16 times as much data as it already has. All those data could reveal subtle signs of novel particles and phenomena.

Still, some researchers say the writing is on the wall for collider physics. “If they don’t find anything, this field is dead,” says Juan Collar, a physicist at the University of Chicago who hunts dark matter in smaller experiments. John Ellis, a theorist at King’s College London, says hopes of a sudden breakthrough have given way to the prospect of a long, uncertain grind toward discovery. “It’s going to be like pulling teeth, not like teeth falling out.”

Since the 1970s, physicists have been locked in a wrestling match with the standard model. It holds that ordinary matter consists of lightweight particles called up quarks and down quarks—which bond in trios to make protons and neutrons—along with electrons and featherweight particles called electron neutrinos. Two sets of heavier particles lurk in the vacuum and can be blasted into fleeting existence in particle collisions. All interact by exchanging other particles: The photon conveys the electromagnetic force, the gluon carries the strong force that binds quarks, and the massive W and Z bosons carry the weak force.

The standard model describes everything scientists have seen at particle colliders so far. Yet it cannot be the ultimate theory of nature. It leaves out the force of gravity, and it doesn’t include mysterious, invisible dark matter, which appears to outweigh ordinary matter in the universe six to one.

And what of naturalness and supersymmetry? The lack of further discoveries puts them in jeopardy:

A notion called naturalness suggested the low mass of the Higgs more or less guaranteed the existence of new particles within the LHC’s grasp. According to quantum mechanics, any particles lurking “virtually” in the vacuum will interact with real ones and affect their properties. That’s exactly how virtual Higgs bosons give other particles their mass.

That physics cuts both ways, however. The Higgs boson’s mass ought to be pulled dramatically upward by other standard model particles in the vacuum—especially the top quark, a heavier version of the up quark that weighs 184 times as much as the proton. That doesn’t happen, so theorists have reasoned that at least one other new particle with a similar mass and just the right properties—in particular, a different spin—must exist in the vacuum to “naturally” counter the effects of the top quark.

The theoretical concept known as supersymmetry would supply such particles. For every known standard model particle, it posits a heavier partner with a different spin. Lurking in the vacuum, those partners would not only keep the Higgs’s mass from running away, but would also help explain how the Higgs field, which pervades the vacuum like an unextinguishable electric field, came into being. Supersymmetric particles might even account for dark matter.

But instead of those hoped-for particles, what have emerged in the past decade are tantalizing anomalies—small discrepancies between observations and standard model predictions—that physicists will explore in the LHC’s next 3-year run.

There's more at the link.

See this post, Lost in Math: Sabine Hossenfelder at Stevens Institute.

H/t 3QD.