Sean Carroll
preposterousuniverse.com · Personal blog · on HN since 2009
Sean Carroll, a theoretical physicist, writes about cosmology, quantum mechanics, and physics, and hosts the Mindscape podcast.
What HN saysHN commenters recommend his explanations and podcast, linking his energy non-conservation post and Mindscape episodes with Max Tegmark and Stewart Brand.
246HN people shared it
178linked it in comments
106stories submitted
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3 months agolast shared
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Most-shared posts
- 1Sean Carroll's Podcast, Mindscape18 people · 6 points · first shared 2019 · discussion on HN
- 2Energy Is Not Conserved (2010)16 people · 60 points · first shared 2015 · 15 comments on HN
- 3Why the Many-Worlds Formulation of Quantum Mechanics Is Probably Correct9 people · 4 points · first shared 2014 · discussion on HN
- 4The Most Embarrassing Graph in Modern Physics9 people · 3 points · first shared 2013 · discussion on HN
- 5The Notorious Delayed-Choice Quantum Eraser – Sean Carroll7 people · 1 points · first shared 2020 · discussion on HN
- 6The Laws Underlying the Physics of Everyday Life Are Completely Understood6 people · 50 points · first shared 2016 · 72 comments on HN
- 7The Universe Is Not a Black Hole5 people · 4 points · first shared 2015 · discussion on HN
- 8Space Emerging from Quantum Mechanics4 people · 131 points · first shared 2016 · 21 comments on HN
- 9Physicists Should Stop Saying Silly Things about Philosophy4 people · 100 points · first shared 2014 · 85 comments on HN
- 10The Alternative-Science Respectability Checklist4 people · 7 points · first shared 2021 · discussion on HN
- 11What Makes Extraordinary Science Extraordinary4 people · 4 points · first shared 2014 · 1 comments on HN
- 12Stephen Wolfram on Computation, Hypergraphs, and Fundamental Physics4 people · 2 points · first shared 2021 · discussion on HN
- 13245 solo the crisis in physics4 people · first shared 2023
- 14Episode 24 kip thorne on gravitational waves time travel and interstellar4 people · first shared 2019
- 15198 nick lane on powering biology4 people · first shared 2022
What HN people wrote when they linked it
scld · 2019-09-11
I'd recommend reading some of the explanations given by Sean Carroll on the subject. https://www.preposterousuniverse.com/
....and I didn't realize that Sean Carroll actually wrote this article! Still, he does some good explanations on his podcast.
ProllyInfamous · 2026-04-03
I'm about 20 minutes into:
>>https://www.preposterousuniverse.com/podcast/2024/05/13/275-solo-quant…
Which was recommended from the top_commenter's link to his own professional QPU programming presentation. I remain interested in learning more about this pure magic.
Ya'lls words both seem to represent worlds which I doubt even more words could help me into ever understanding(s).
I definitely understand being "in multiple states at the same time" — — —
steve_adams_86 · 2026-01-20
Sean Carroll interviews Stewart about this book on his latest podcast episode:
https://www.preposterousuniverse.com/podcast/2026/01/19/341-stewart-br…
I really enjoyed it. I'll probably get a copy of this. I loved the thermodynamics analogy in the start of the podcast, likening maintenance to the prevention of entropy, with all the energetic exchanges that entails. Though maintenance does take work, it's worth it. Stewart makes a compelling case for it.
mr_mitm · 2025-11-07
Maybe this helps: https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-con…
My favorite quote:
> I like to think that, if I were not a professional cosmologist, I would still find it hard to believe that hundreds of cosmologists around the world have latched on to an idea that violates a bedrock principle of physics, simply because they “forgot” it. If the idea of dark energy were in conflict with some other much more fundamental principle, I suspect the theory would be a lot less popular.
eprparadox · 2025-10-09
there's a great episode of Mindscape where Max Tegmark takes this idea and runs with it: https://www.preposterousuniverse.com/podcast/2019/12/02/75-max-tegmark…
antognini · 2025-08-21
As a counterbalance to the "renegade" character of these kinds of podcasts I do recommend Sean Carroll's Mindscape podcast. He does a good job representing the "establishment" position in physics, so to speak.
A good episode to start with is "The Crisis in Physics" in which he (unusually?) argues that there is no real crisis in physics.
https://www.preposterousuniverse.com/podcast/2023/07/31/245-solo-the-c…
randomtoast · 2025-06-12
It is well possible that GPT-4.1 references Sean Carroll, either directly or by regurgitation.
> One sometimes hears the claim that the Big Bang was the beginning of both time and space; that to ask about spacetime “before the Big Bang” is like asking about land “north of the North Pole.”
Source: https://www.preposterousuniverse.com/writings/dtung/
I'm a regular listener of his Mindscape podcast, and that's where I got this phrase. I can highly recommend his podcast: https://www.preposterousuniverse.com/podcast/
consumer451 · 2025-05-25
Sean Carroll has talked about your concerns. This is impressively apolitical for the most part, and covers much of what you have brought up. I highly recommend listening or reading.
https://www.preposterousuniverse.com/podcast/2025/02/12/bonus-cuts-to-…
khold_stare · 2025-02-23
Thanks for the kind words! For anyone curious to dive deeper into the crazyness that is quantum mechanics I can highly recommend a few resources:
- Sean M Carroll's work, in particular his Biggest Ideas in the Universe books: https://www.preposterousuniverse.com/biggestideas/
- Artur Ekert, basically the father of Quantum Cryptography has an amazing course for free on youtube: https://www.youtube.com/@ArturEkert . It's a very precise and understandable explanation of quantum computing, and some of the math that is involved with quantum mechanics.
- If you have hours to spare, watch Richard Behiel's videos on Youtube. He's like the 3Blue1Brown of Quantum Physics. His latest video on superconductivity and the Higgs Field is almost 5 hours long (!!!) https://youtu.be/DkH1citHtgs?si=-yQNYDu9TlTpE1A0 . It builds on his other videos, so I'd recommend starting at the beginning.
homebrewer · 2024-12-10
See also this fantastic podcast (if I remember the episode correctly, although it doesn't matter much as they're all good and he talks about the subject frequently because it's tightly related to his day job)
https://www.preposterousuniverse.com/podcast/2022/06/06/200-solo-the-p…
layer8 · 2024-10-19
I recommend taking a listen to these podcast episodes to get an understanding of why string theory won’t be discarded anytime soon:
https://www.preposterousuniverse.com/podcast/2018/10/15/episode-18-cli…
https://www.preposterousuniverse.com/podcast/2019/01/28/episode-31-bri…
sandgiant · 2024-10-04
Sean Carroll (professor of physics, quoted in the article) has a highly-rated book titled "Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime" [1] which discusses exactly these topics. I haven't read it, but it's on my list.
I also highly recommend his podcast "Mindscape" where he discusses this and a range of other topics in science and philosophy. [2]
[1] https://www.preposterousuniverse.com/somethingdeeplyhidden/ [2] https://www.preposterousuniverse.com/podcast/
lanstin · 2024-07-18
The only one I've listened to was him interviewing Donald Knuth which was worth listening to, tho from time to time I got the impression of an interviewer that didn't quite know enough to do the interview.
If you like podcasts of a very intelligent person interviewing very accomplished guest thinkers, Sean Carroll's Mindcast is slightly higher level: https://www.preposterousuniverse.com/podcast/ (tho I don't think Donald Knuth has been on that one, lots of other computer folks have).
vinnyvichy · 2024-06-04
Ah you mean Schmidhuber's speed prior: https://people.idsia.ch/~juergen/speedprior.html
I was more interested in pointing to you the measly followups to Aaronson's question, which consists solely of forays into nonlinear quantum mechanics & superluminal neutrinos.
https://www.preposterousuniverse.com/blog/2011/09/24/can-neutrinos-kil…
WantonQuantum · 2024-06-04
Sean Carroll’s site is a great place to read about this sort of stuff in an accessible way:
https://www.preposterousuniverse.com/blog/2016/07/18/space-emerging-fr…
elashri · 2024-03-20
I'm sorry if I'm confusing. That's the term I use, usually assuming that it is obvious (like referring to C++ templates to a python developer without explaining what is that).
To be honest, it is hard to visualize, as it is counterintuitive of what we think of space. While I know many people would disagree, I really like the garden hose analogy [1]. The idea is to simply imagine a very long garden hose. From a great distance, it looks like a one-dimensional line. Now you get closer, and realize it has a second dimension, which is its circumference curled around that seemingly 1-D line. An ant walking on the hose can move along its length, but also in a circle around it. The extra dimension in KK is like this circumference. It is tiny, curled up so we don't directly notice it, but still potentially there.
[1] https://www.preposterousuniverse.com/blog/2004/06/30/extra-dimensions/
jahnu · 2024-03-07
Mindscape episode with Stephen Wolfram from 2021 which might also be of interest. I enjoyed it even if most of it was way over my head. It is probably overly-ambitious and probably a dead end but it's an worthy attempt (if you have the money) and he's definitely not a crank. Eccentric maybe though.
https://www.preposterousuniverse.com/podcast/2021/07/12/155-stephen-wo…
ithkuil · 2024-02-17
The "why is there something rather than nothing" is a fascinating and mind boggling philosophical question.
A good read is https://www.preposterousuniverse.com/blog/2018/02/08/why-is-there-some…
nh23423fefe · 2023-08-08
As a layman, I can't follow, but the paper [1] references AQUAL [2] "This systematic deviation agrees with the boost factor that the AQUAL theory predicts." But that theory doesn't agree with observation? And I'll paraphrase Sean Carroll [3] as saying something like Scalar-vector-tensor theories are just dark matter theories in disguise. Positing an noninteracting energy density, is just positing dark matter.
1 https://arxiv.org/pdf/2305.04613.pdf
2
https://en.wikipedia.org/wiki/AQUAL#:~:text=AQUAL%27s%20failure%20to%2…
3 https://www.preposterousuniverse.com/podcast/2023/07/31/245-solo-the-c…
slowmovintarget · 2022-07-18
On "not the path to AGI": Gary Marcus on the Mindscape podcast is worth a listen.
https://www.youtube.com/watch?v=ANRnuT9nLEE&list=PLrxfgDEc2NxY_fRE…
Transcript: https://www.preposterousuniverse.com/podcast/2022/02/14/184-gary-marcu…
"...And then there’s natural language understanding and reasoning, and I would say we have not really made progress at all. GPT-3, which we may wanna talk about, gives the illusion of having natural language of understanding, but I don’t really think that it does. And we are nowhere near, for example, an all-purpose general assistant. ..."
mturmon · 2022-06-15
I believe the community consensus (based on surveys) is that there aren't enough microlensing events to explain the amount of dark matter we see, using MACHOs.
You can read this even at: https://en.wikipedia.org/wiki/Massive_compact_halo_object
I believe that I most recently heard it from Lina Necib's appearance on Sean Carroll's podcast ... that would be this episode: https://www.preposterousuniverse.com/podcast/2020/05/11/96-lina-necib-…
Recommended, if you go for that sort of thing.
[Edited to add: OK, turns out the consensus is unstable. There appears to be a window of BH mass range which has not been observationally excluded. See, e.g.https://en.wikipedia.org/wiki/Primordial_black_hole#Theoretical_histor…
mihaitodor · 2022-06-12
Sean Carroll's site https://www.preposterousuniverse.com/ and podcast https://www.preposterousuniverse.com/podcast/ where he interviews various people about physics, biology, math, psychology, philosophy etc.
russdill · 2022-02-16
Excellent discussion between the author and Sean Carroll on the subject.
https://www.preposterousuniverse.com/podcast/2021/10/18/169-c-thi-nguy…
themarlzy · 2022-01-18
I found Sean Carroll’s Mindscape podcast episode on smell to be insightful on this[0]. My understanding? Not anywhere close.
0 https://www.preposterousuniverse.com/podcast/2020/07/13/105-ann-sophie…
rossvor · 2021-12-27
I would also add episode with Michael Levin as a worthy candidate for this year.
https://www.preposterousuniverse.com/podcast/2021/02/01/132-michael-le…
ddeck · 2021-11-06
For those interested in hearing about his theory/work, Sean Carroll (theoretical physicist) did a very long podcast with him about it.
I'd highly recommend Sean's podcast in general for those interested in physics topics and prefer a more technical discussion that the usual physics podcasts.
https://www.preposterousuniverse.com/podcast/2021/07/12/155-stephen-wo…
superjan · 2021-07-22
If you have an hour to spare and are interested in what quantum computers might be good for in the long run, I recommend this interview(podcast, Sean Carrol’s Mindscape):
https://www.preposterousuniverse.com/podcast/2021/06/28/153-john-presk…
jpmattia · 2021-06-15
If you are a fan of podcasts: Sean Carroll's interview with Kip Thorne was worth a listen.
https://www.preposterousuniverse.com/podcast/2018/11/26/episode-24-kip…
jimhefferon · 2021-05-20
Folks who, like me, are interested but not professional physicists, may find illuminating Sean Carroll's podcast. https://www.preposterousuniverse.com/podcast/ He is a CalTech faculty physicist with wide interests and perhaps a third of the episodes are about research physics. I remember several that discussed wormholes and associated topics seriously, from the standpoint of world-class researchers. I think anyone interested in HN would be able to follow the conversations closely.
freetonik · 2020-12-28
Sean Carroll's Mindscape[1] is by far my favourite podcast.
[1]. https://www.preposterousuniverse.com/podcast/