I’m back with my friend and colleague Sabine Hossenfelder for another episode of “What’s New in Science”. I think this is one of my favorite dialogues that we have had. Spending time with Sabine was a nice chance to step away from my physics lecture series for a bit. I know many of you have been enjoying the lectures, so don’t worry, they’ll be back soon.

In this episode, we covered the kind of science news I like best: ideas you can argue about and results that make you recalibrate. Sabine opened with describing a clever proposal that future fusion reactors might double as axion dark matter factories, producing a flux of very light, weakly interacting particles through neutron-lithium reactions in the shielding. That led to a discussion about what people mean by “axions,” why particle physicists tend to be more particular about the term, and why I’m always more interested in dark matter candidates that were invented to solve an actual problem, not just to fill a cosmological gap. From there we jumped to quantum mechanics at the edge of common sense, with a Vienna experiment showing interference from a cluster of thousands of atoms, and a friendly disagreement about whether “collapse” is a real physical process or just the wrong way to talk about what quantum mechanics is doing.

We also talked about AI and math, including the recent swirl of claims about machines proving famous open problems, what was hype, what was rediscovery, and what might genuinely be changing in how mathematicians search the landscape. Then we went from equations to extinction, with a fascinating new approach using space dust and helium isotopes to argue that life may have started rebounding after the Chicxulub impact far faster than people had assumed. Sabine brought a surprising example of string theory mathematics finding a practical use in modeling biological networks, and we ended with biology proper in two very different moods: a sobering study in mice suggesting lung tumors can hijack vagus nerve signaling to suppress local immune responses, and then a lighter result about dogs learning words from overheard human conversation at roughly toddler level. My dog Levi, who many of you have seen on the podcast, was asleep next to me while we talked about it, which felt like the right way to end.

As always, thank you for your continued support, and I hope the changing of seasons brings you good time with friends and family.

As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube.

Any sufficiently advanced technology is indistinguishable from magic, as Arthur C. Clarke put it. In that spirit, the way we get closest to “magic” in physics is not by memorizing more facts or equations, but by learning a few mental tools that help us see through the illusion of complexity by extracting the wheat from the chaff. They are all simple at heart, but nevertheless quite powerful, and they form the core of what I call the Gestalt of Physics—the worldview that governs how physicists approach nature. And some of them can actually seem like magic to the uninitiated!

I’m also pleased to share a quick PSA. We’re organizing our next Origins travel adventure: a sailing expedition through the Greek archipelago (July 24 to 31) with a possible Cyprus add-on (July 18 to 23). If you’re interested, it’s worth raising your hand early. These trips tend to fill quickly. Express interest at http://originsproject.org/greece-2026

In Lecture 1, I used powers of ten as an intellectual zoom lens, a way to escape the trap of human scale. Lecture 2 steps back and asks a more fundamental question: how do physicists consistently make progress when the world looks hopelessly complicated?

This lecture focuses on the fundamental toolkit for seeing. We will use these tools throughout the series, because they are the difference between being dazzled by nature and being able to interrogate it, and ultimately understand it.

First, order of magnitude thinking, the art of using powers of ten and rough estimates. It is how you keep your intuition tethered to reality, and how you avoid being bullied by big numbers dressed up with false precision.

Second, approximation, which is where I introduce my super cow. It is not only a spherical cow. It’s better. My super cow has exactly the features we need for the question at hand, no more, no less, and it politely agrees to ignore everything irrelevant. I introduce it with a joke, but it is also the core of how we turn messy reality into something we can actually calculate without lying to ourselves.

Third, dimensional analysis, one of the great bargains in science. The fact that there are essentially only 3 fundamental ‘dimensional’ quantities describing nature—Length, Time, and Mass—means that all physical quantities can be related to other physical quantities through a small set of relations. Keeping track of dimensions allows us to often guess what the relations are, without knowing any details of specific physical situations. It seems like magic. By keeping track of the dimensions underlying quantities, you can often infer the form of an answer and you can catch nonsense instantly. Sometimes the most important result is realizing something cannot be right, because that is where new physics likes to hide.

Along the way I adopt some Fermi style challenges—named after the remarkable physicist Enrico Fermi—to show how these ideas work in real time, and why they are not parlor tricks. They provide a training in scientific judgment. I also end with a preview of what comes next, symmetry, a concept that quietly runs far more of the universe than most people realize.

Enjoy, and feel free to share.

Lawrence

As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube.

New Year’s Eve always comes with that familiar urge to clean the slate, toss out what didn’t hold up, and keep what actually earned its place. That’s basically the spirit of our latest “What’s New in Science” episode with Sabine Hossenfelder.

We began with the season’s favorite shiny object: wormholes. The headlines have been everywhere, but we talked through why most of these stories quietly slide from “a speculative tool in a model” to “a virtual phenomenon that might be useful in calculations.” Traversable wormholes of course still run straight into hard constraints like negative energy and the time machine problem.

From there we moved to something much more grounded: CERN. ATLAS has now observed the Higgs decaying into muon pairs, which is exactly the kind of precise confirmation you want for the Standard Model, and while it is yet another remarkable confirmation of how well the fundamental feature of the Standard Model works, it once again sharpens the contrast with the inexplicable nature of the only feature that doesn’t seem to fit: neutrino masses. And it leaves us hanging about where to look next.

We next spent time on what the future might look like for big particle collider projects and what it says about the field’s priorities, including the signal sent by China’s latest five-year plan, which no longer features a massive circular collider proposal. We touched on a smaller CERN result as well, and used it to reflect on a broader point: some of the most stubborn, interesting physics lives in regimes that are messy rather than glamorous.

Then we took a quick detour into a quantum gravity-adjacent proposal about whether the way we average quantities in general relativity could matter for quantum corrections, and finally landed on a genuinely satisfying closer: OSIRIS-REx’s Bennu samples. Finding ribose alongside other prebiotic building blocks makes it harder to dismiss the idea that the chemistry of life might be widespread, and not a once-only cosmic fluke.

I hope you enjoy the episode, and I hope you’re welcoming the new year surrounded by friends and family. Thank you, as always, for listening and for your continued support.

As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project YouTube.