Machine learning using neural networks has led to a remarkable leap forward in artificial intelligence, and the technological and social ramifications have been discussed at great length. To understand the origin and nature of this progress, it is useful to dig at least a little bit into the mathematical and algorithmic structures underlying these techniques. Anil Ananthaswamy takes up this challenge in his book Why Machines Learn: The Elegant Math Behind Modern AI. In this conversation we give a brief overview of some of the basic ideas, including the curse of dimensionality, backpropagation, transformer architectures, and more.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/11/24/336-anil-ananthaswamy-on-the-mathematics-of-neural-nets-and-ai/

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Anil Ananthaswamy received a Masters degree in electrical engineering from the University of Washington, Seattle. He is currently a freelance science writer and feature editor for PNAS Front Matter. He was formerly the deputy news editor for New Scientist, a Knight Science Journalism Fellow at MIT, and journalist-in-residence at the Simon Institute for the Theory of Computing, University of California, Berkeley. He organizes an annual science journalism workshop at the National Centre for Biological Sciences at Bengaluru, India.

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Welcome to the November 2025 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number -- based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good -- and sometimes group them together if they are about a similar topic. Enjoy!

Blog post with AMA questions and transcript: https://www.preposterousuniverse.com/podcast/2025/11/17/ama-november-2025/

In the intro I mentioned a couple of my favorite TV shows of this year. Here is a more thought-out list (no particular order):

• Slow Horses
• Murderbot
• The Residence
• Poker Face
• Severance

Pluribus and Down Cemetery Road also look promising, but too early to tell. (There are a huge number of shows I've never seen, so feel free to add recommendations.)

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Science has an incredibly impressive track record of uncovering nonintuitive ideas about the universe that turn out to be surprisingly accurate. It can be tempting to think of scientific discoveries as being carefully constructed atop a rock-solid foundation. In reality, scientific progress is tentative and fallible. Scientists propose models, assign them probabilities, and run tests to see whether they succeed or fail. In cosmologist Andrew Jaffe's new book, The Random Universe, he illustrates how models and probability help us make sense of the cosmos.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/11/10/335-andrew-jaffe-on-models-probability-and-the-universe/

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Andrew Jaffe received his Ph.D. in physics from the University of Chicago. He is currently a professor of astrophysics and cosmology and Director of the Imperial Centre for Inference and Cosmology at Imperial College, London. His research lies at the intersection of theoretical and observational cosmology, including the Planck Surveyor, Euclid, LISA, and Simons Observatory collaborations.

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The universe as revealed by physics is objective: it's out there, existing and behaving in ways that are completely independent of human thought. But the process by which we learn about the universe, and the language with which we talk about it, is extremely human-dependent. Does that mean that aliens would do science differently, and even think differently about physics, even if we all live in the same universe? Physicist Daniel Whiteson has teamed with cartoonist Andy Warner to investigate these questions in their new book Do Aliens Speak Physics?

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/11/03/334-daniel-whiteson-on-the-physics-of-and-by-aliens/

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Daniel Whiteson received his Ph.D. in physics from the University of California at Berkeley. He is currently a professor of physics at the University of California, Irvine. He is a Fellow of the American Physical Society and recipient of an Emmy nomination. He is the author of several books, often with co-author Jorge Cham. He is the co-host (with Kelly Weinersmith) of the podcast Daniel and Kelly's Extraordinary Universe.

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Why are people wrong all the time, anyway? Is it because we human beings are too good at being irrational, using our biases and motivated reasoning to convince ourselves of something that isn't quite accurate? Or is it something different -- unmotivated reasoning, or "unthinkingness," an unwillingness to do the cognitive work that most of us are actually up to if we try? Gordon Pennycook wants to argue for the latter, and this simple shift has important consequences, including for strategies for getting people to be less susceptible to misinformation and conspiracies.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/10/27/333-gordon-pennycook-on-unthinkingness-conspiracies-and-what-to-do-about-them/

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Gordon Pennycook received his Ph.D. in psychology from the University of Waterloo. He is currently an associate professor of psychology and Dorothy and Ariz Mehta Faculty Leadership Fellow at Cornell University as well as an Adjunct Professor at University of Regina’s Hill/Levene Schools of Business. He is a member of the Royal Society of Canada's College of New Scholars, Artists, and Scientists, and a 2016 winner of the IgNobel Prize for Peace.

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Music is math that you can dance to. The fact that certain notes sound good when played together, or in succession, is related to the mathematical properties of the frequencies to which they correspond, an idea that goes back as far as Pythagoras himself. These days we have a much more intricate understanding of these relationships and how to manipulate them. I talk to composer and music theorist Dmitri Tymoczko about how different musical scales are constructed and the math underlying what sounds good.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/10/20/332-dmitri-tymoczko-on-the-mathematics-behind-music/

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Dmitri Tymoczko received a Ph.D. in music composition from the University of California, Berkeley. He is currently a professor of music at Princeton University as well as a composer and performer. He has been the recipient of Rhodes and Guggenheim fellowships. As a composer, his works have been performed by multiple groups, and recorded on several albums.

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• Spiral diagrams: rock music, classical music
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• William Sethares's Tuning Timbre Spectrum Scale

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Welcome to the October 2025 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number -- based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good -- and sometimes group them together if they are about a similar topic. Enjoy!

Blog post with AMA questions and transcript: https://www.preposterousuniverse.com/podcast/2025/10/13/ama-october-2025/

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Certain features of our universe seem unnatural to us. These include "constants of nature" such as the cosmological constant and the mass of the Higgs boson, as well as features of the initial conditions like the curvature of space and the initial entropy. But they can't truly be "unnatural" -- they are literally features of Nature itself. Some have turned to the anthropic principle and the multiverse, while others look to theism for an explanation. I talk here about my views on the various attitudes one might take toward these apparent fine-tunings, and why it is important to think about them.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/10/06/331-solo-fine-tuning-god-and-the-multiverse/

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Some readings of relevance:

• Livio and Rees, Fine-Tuning, Complexity, and Life in the Multiverse
• Carroll, In What Sense Is the Early Universe Fine-Tuned?
• Barnes, A Reasonable Little Question: A Formulation of the Fine-Tuning Argument
• Goff, Our Improbable Existence Is No Evidence for a Multiverse
• Neal, Puzzles of Anthropic Reasoning Resolved Using Full Non-indexical Conditioning

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A characteristic of complex systems is that individual components combine to exhibit large-scale emergent behavior even when the components were not specifically designed for any particular purpose within the collective. Sometimes those individual components are us -- people interacting within societies or online communities. Studying the dynamics of such interactions is interesting both to better understand what is happening, and hopefully to designing better communities. I talk with Petter Törnberg about flows of information, how polarization develops, and how artificial agents can help steer things in better directions.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/09/29/330-petter-tornberg-on-the-dynamics-of-misinformation/

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Petter Törnberg received a Ph.D. in complex systems from Chalmers University of Technology. He is now an Assistant Professor at the Institute for Language, Logic and Computation at the University of Amsterdam, Associate Professor in Complex Systems at Chalmers University of Technology, NWO VENI laurate, and senior researcher at the University of Neuchâtel.

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Getting along in society requires that we mostly adhere to certainly shared norms and customs. Often it's not enough that we all know what the rules are, but also that everyone else knows the rules, and that they know that we know the rules, and so on. Philosophers and game theorists refer to this as common knowledge. In Steven Pinker's new book, When Everyone Knows That Everyone Knows..., he explores how common knowledge (or its absence) explains money, power, and a wide variety of subtextual human interactions.

Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/09/22/329-steven-pinker-on-rationality-and-common-knowledge/

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Steven Pinker received his Ph.D. in psychology from Harvard University. He is currently the Johnstone Family Professor of Psychology at Harvard University. He is the author of several best-selling books and recipient of several honorary doctoral degrees. Among his awards are Humanist of the Year (two different organizations) and the William James Lifetime Achievement Award from the Association for Psychological Science.

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