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Sean Carroll

@seanmcarroll.bsky.social

38K followers 580 following 7.9K posts

Physics, philosophy, complexity. @jhuartssciences.bsky.social & @sfiscience.bsky.social. Host, #MindscapePodcast. Married to @jenlucpiquant.bsky.social. Latest books: The Biggest Ideas in the Universe. https://preposterousuniverse.com/

preposterousuniverse.com

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Sean Carroll @seanmcarroll.bsky.social · Sep 5

Postdoc job! I expect to have an opening at Johns Hopkins for a postdoctoral researcher working somewhere in the broad realms of physics, philosophy, and complexity. Apply at Academic Jobs Online:

academicjobsonline.org/ajo/jobs/30496

Johns Hopkins University, Physics and Astronomy

Job #AJO30496, Postdoctoral Fellow in Foundations of Physics, Complexity, and Emergence, Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland, US

academicjobsonline.org

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Sean Carroll @seanmcarroll.bsky.social · 1h

Strong truth here from @himself.bsky.social. Civil society has to get its act together and coordinate for the greater good, even if that's not its usual mode. Universities most especially.

Henry Farrell @himself.bsky.social · 2h

"It wanted to signal strength. Instead, it’s revealing its weakness. The administration’s need to break the academy is forcing it to make a desperately risky gamble." www.nytimes.com/2025/10/08/o...

Opinion | You Beat Trumpism by Banding Together. It’s as Hard and as Simple as That.

www.nytimes.com

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Sean Carroll @seanmcarroll.bsky.social · 17h

One of the macro variables is the entropy, the log of the number of microstates in a macrostate. We saw how this connected with the previous phenomenological definition in terms of heat flow. Now we can start asking the Why questions.

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Sean Carroll @seanmcarroll.bsky.social · 17h

The coarse-graining step, mapping a large number of microstates of particles into a single macroscopic fluid description, is of course fraught with philosophical peril. Who decides what coarse-graining is the right one? Ultimately it’s what gives an effective emergent higher-level theory.

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Sean Carroll @seanmcarroll.bsky.social · 17h

Today in #PhilosophyOfCosmology we started in on statistical mechanics proper. It was a bold move to think that the rules of thermodynamics could be derived from an assumption of underlying particulate structure, plus an appropriate coarse-graining and some assumptions about probabilities.

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Reposted by Sean Carroll

Chris Murphy @chrismurphyct.bsky.social · 18h

This has nothing to do with crime. This is an attempt to crush political dissent.

Never before, in our entire 250 year history, has the military or immigration agents been used like this. It's dystopian, illegal, and it should stop.

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Sean Carroll @seanmcarroll.bsky.social · 18h

It seems pretty clear that if everyone hits their ceilings (including Embiid and PG), it's a championship-level roster. All of the angst comes from the apparent unlikelihood of that happening.

Sean Carroll @seanmcarroll.bsky.social · 22h

Metajokes about how readers may apply different grammatical construals to sentences are by definition good.

Sean Carroll @seanmcarroll.bsky.social · 23h

Such an exciting area of physics these days.

Artemy Kolchinsky @artemyte.bsky.social · 1d

After a long time in the making, my paper on nonequilibrium thermodynamics of Darwinian evolution has been published in Philosophical Transactions B. Updated version: arxiv.org/abs/2112.02809

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Sean Carroll @seanmcarroll.bsky.social · 1d

(I have no judgment on the academic paper in question, just happy to see Mindscape making an impact.)

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Sean Carroll @seanmcarroll.bsky.social · 1d

The notion being stolen was "any allusion to conscious LLMs is an illusion; it’s a deep fake on steroids."

The podcast in question:

www.preposterousuniverse.com/podcast/2025...

Title card for Mindscape podcast episode with Christof Koch on Consciousness and Integrated Information.

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Sean Carroll @seanmcarroll.bsky.social · 1d

Love it when a paper on arXiv includes a footnote reading "We stole this notion from Christof Koch (March 24, 2025, Mindscape podcast by Sean Carroll)."

arxiv.org/abs/2510.03311

Not Even Wrong: On the Limits of Prediction as Explanation in Cognitive Science

We offer a comment on the Centaur (Binz et al., 2025) transformer-based model of human behavior. In particular, Centaur was cast as a path towards unified theories of cognition. We offer a counter cla...

arxiv.org

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Reposted by Sean Carroll

Nick Kodama 🌲👻 @nickkodama.bsky.social · 1d

Should've used this photo

Guy in a frog costume facing ICE/police in Portland with the caption "analysis: what is the insurrection act"

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Sean Carroll @seanmcarroll.bsky.social · 1d

After stretching a bit last year, this year the Nobel committee was determined to give the prize to the physicsiest physics that ever physicsed.

The New York Times @nytimes.com · 1d

Breaking News: The Nobel Prize in Physics was awarded to John Clarke, Michel Devoret and John Martinis for their work in quantum mechanics.

Nobel Prize in Physics Is Awarded for Work in Quantum Physics

The prize was awarded to John Clarke, Michel H. Devoret and John M. Martinis.

nyti.ms

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Reposted by Sean Carroll

British Journal for the Philosophy of Science @thebjps.bsky.social · 1d

Are you a phd student? Are you in the vicinity of one and want to help them with their bad life choices? Then this is for you! #philsci

Philosophy of Science Association @philsci.bsky.social · 1d

✨Don't forget✨ PSA Office Hours are back! Join us this Thursday, October 9 at 12 PM EST with S. Andrew Schroeder. Sign up at the link below to save your spot!

www.philsci.org/psa_...

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Sean Carroll @seanmcarroll.bsky.social · 1d

I know I’m safe from winning the Nobel Prize because there’s no way I’m answering a phone call at 4am or whatever. They’re just going to give up and move on to the next choice. (Could have happened several times already, you don’t know.)

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Reposted by Sean Carroll

Robert “The Bobby Yaga” McNees @mcnees.bsky.social · 1d

VAR!

In the early morning hours #OTD in 1923, Edwin Hubble took a photo plate of M31 that showed a Cepheid variable star.

Using Henrietta Swan Leavitt’s distance-luminosity relationship, Hubble concluded that M31 is another galaxy outside the Milky Way. 🧪 🔭 ⚛️

Image: Carnegie Observatories

Photo plate of Hubble's famous "VAR!" discovery. This is a photonegative plate of an image of the Andromeda Galaxy, with several small annotations made in grease pencil. One of them was previously marked "N" for "nova," but the N has been crossed out and replaced with an excited "VAR!" to indicate a Cepheid Variable.

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Sean Carroll @seanmcarroll.bsky.social · 1d

I think we need more evidence that inflation actually happened.

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Sean Carroll @seanmcarroll.bsky.social · 1d

But also a good opportunity to hammer home the mental script we should all run when faced with a new quantum system:

* What's the Hamiltonian?
* What are other interesting observables?
* What are the eigenstates and eigenvalues of the above?

I'm sure that's what you all do.

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Sean Carroll @seanmcarroll.bsky.social · 1d

We then began the journey to find the eigenstates and eigenvalues. Mostly this amounted to be very careful about how to turn compact tensor-product notation into practical matrix notation. Didn't quite finish; these 50-minute class times are killing me.

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Sean Carroll @seanmcarroll.bsky.social · 1d

After a day off for a midterm exam, we are back to teaching #QM1. Today we continued our dive into composite systems and tensor products. We took the simplest example (2 spins) and wrote down a Hamiltonian, including both self-terms (spin interacting with a magnetic field) and a spin-spin coupling.

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Sean Carroll @seanmcarroll.bsky.social · 1d

Wish lists should not be construed as predictions!

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Sean Carroll @seanmcarroll.bsky.social · 1d

Since last year Physics swallowed Computer Science whole and the Nobel was given for machine learning, my list of plausible prizes remains unaltered.

Sean Carroll @seanmcarroll.bsky.social · Oct 7

Physics Nobels I would be pleased by:

Quantum info (Bennett, Shor...)

CMB anisotropy measurements (not sure who)

LHC/Higgs discovery (Evans, Giannotti...)

Systems biophysics (West, Bialek...)

Not predictions! And of course many other areas I don't know enough about to guess.

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Sean Carroll @seanmcarroll.bsky.social · 2d

Mindscape 331 | Solo: Fine-Tuning, God, and the Multiverse. In which I shamelessly steal material from the #PhilosophyOfCosmology course I am teaching to talk about some big questions. #MindscapePodcast

www.preposterousuniverse.com/podcast/2025...

Title card for Mindscape Podcast episode on Fine-Tuning, God, and the Multiverse.

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Reposted by Sean Carroll

Paul Guinnessy @paulguinnessy.bsky.social · 2d

I think he meant “democracy”

#25thAmendmentNow

Aaron Rupar @atrupar.com · 2d

Trump to the Navy: "We have to take care of this little gnat that's on our shoulder called the Democrats."

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Sean Carroll @seanmcarroll.bsky.social · 2d

The Earth deserves all the credit, really.

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