Dave Bacon
@dabacon.tachyon.institute
Theoretical ski bum. Former pseudo professor. Quantum bridge builder. Will math for food.
mastodon: @[email protected]
https://dabacon.org
mastodon: @[email protected]
https://dabacon.org
Pinned
Dave Bacon
@dabacon.tachyon.institute
· Apr 25
Much Madness is divinest Sense -
To a discerning Eye -
Much Sense - the starkest Madness -
’Tis the Majority
In this, as all, prevail -
Assent - and you are sane -
Demur - you’re straightway dangerous -
And handled with a Chain -
—Emily Dickinson
To a discerning Eye -
Much Sense - the starkest Madness -
’Tis the Majority
In this, as all, prevail -
Assent - and you are sane -
Demur - you’re straightway dangerous -
And handled with a Chain -
—Emily Dickinson
The Tandem Non Stop youtu.be/SSSB7ZTSXH4?...
The Remarkable Computers Built Not to Fail
YouTube video by Asianometry
youtu.be
January 12, 2026 at 4:45 AM
The Tandem Non Stop youtu.be/SSSB7ZTSXH4?...
Wowah turns out the father of the modern surf board was the brother of “tutu man” at Caltech. legendary-surfers.blogspot.com/2017/03/bob-...
Bob Simmons (1919-1954)
Comprehensive writings on the history of surfing, surf culture and legendary surfers.
legendary-surfers.blogspot.com
January 8, 2026 at 6:08 AM
Wowah turns out the father of the modern surf board was the brother of “tutu man” at Caltech. legendary-surfers.blogspot.com/2017/03/bob-...
New president at Caltech announced, astrophysicist Ray Jayawardhana www.caltech.edu/about/news/r...
Ray Jayawardhana - Wikipedia
en.wikipedia.org
January 6, 2026 at 7:15 PM
New president at Caltech announced, astrophysicist Ray Jayawardhana www.caltech.edu/about/news/r...
Reposted by Dave Bacon
Reposted by Dave Bacon
Much later Einstein postulated that the universe was a 3-sphere. But Dante got the idea first:
• Mark A. Peterson, Dante and the 3-sphere, American Journal of Physics 47 (1979), 1031-1035. physicsgg.me/wp-content/u...
(2/2)
mathstodon.xyz/@johncarlosb...
• Mark A. Peterson, Dante and the 3-sphere, American Journal of Physics 47 (1979), 1031-1035. physicsgg.me/wp-content/u...
(2/2)
mathstodon.xyz/@johncarlosb...
John Carlos Baez (@[email protected])
Attached: 1 image
Apparently Dante conceived of the universe as a 3-sphere! That's a 3-dimensional space formed by taking two solid 3-dimensional balls and completely gluing their surfaces together...
mathstodon.xyz
January 2, 2026 at 2:45 PM
Much later Einstein postulated that the universe was a 3-sphere. But Dante got the idea first:
• Mark A. Peterson, Dante and the 3-sphere, American Journal of Physics 47 (1979), 1031-1035. physicsgg.me/wp-content/u...
(2/2)
mathstodon.xyz/@johncarlosb...
• Mark A. Peterson, Dante and the 3-sphere, American Journal of Physics 47 (1979), 1031-1035. physicsgg.me/wp-content/u...
(2/2)
mathstodon.xyz/@johncarlosb...
"It’s just embarrassing that we don’t have a story we can tell people about what reality is" - Carl Caves
www.quantamagazine.org/its-a-mess-a...
www.quantamagazine.org/its-a-mess-a...
‘It’s a Mess’: A Brain-Bending Trip to Quantum Theory’s 100th Birthday Party | Quanta Magazine
Hundreds of physicists (and a few journalists) journeyed to Helgoland, the birthplace of quantum mechanics, and grappled with what they have and haven’t learned about reality.
www.quantamagazine.org
January 2, 2026 at 5:05 PM
"It’s just embarrassing that we don’t have a story we can tell people about what reality is" - Carl Caves
www.quantamagazine.org/its-a-mess-a...
www.quantamagazine.org/its-a-mess-a...
Reposted by Dave Bacon
Although 2025 was absolutely shocking in terms of the cruelty of powerful people, science can still be a refuge from it. A highlight for me was retreating to the mountains to teach at the Les Houches Summer School. Here are my lecture notes: arxiv.org/abs/2512.24390
Les Houches Lectures Notes on Tensor Networks
Tensor networks provide a powerful new framework for classifying and simulating correlated and topological phases of quantum matter. Their central premise is that strongly correlated matter can only b...
arxiv.org
January 1, 2026 at 8:36 AM
Although 2025 was absolutely shocking in terms of the cruelty of powerful people, science can still be a refuge from it. A highlight for me was retreating to the mountains to teach at the Les Houches Summer School. Here are my lecture notes: arxiv.org/abs/2512.24390
Reposted by Dave Bacon
Last year I wrote about a paper on the idea of black holes made purely from light, and why it doesn't seem possible. Now one of the proponents of the idea, Don Page, has argued that there are still circumstances in which they could happen.
journals.aps.org/prl/abstract...
journals.aps.org/prl/abstract...
Light Black Holes from Light
\'Alvarez-Dom\'{\i}nguez et al. [Phys. Rev. Lett. 133, 041401 (2024)] have suggested that ``it is not possible to concentrate enough light to precipitate the formation of an event horizon. We argue th...
journals.aps.org
December 30, 2025 at 11:29 AM
Last year I wrote about a paper on the idea of black holes made purely from light, and why it doesn't seem possible. Now one of the proponents of the idea, Don Page, has argued that there are still circumstances in which they could happen.
journals.aps.org/prl/abstract...
journals.aps.org/prl/abstract...
My year in reading dabacon.org/pontiff/2025...
2025 in Books
While the world is burning down with quantum hype, this reformed quantum computing blog is now a book blog. Always has been. This year my links are affiliate links, I will maybe earn a beer if all …
dabacon.org
December 29, 2025 at 9:40 PM
My year in reading dabacon.org/pontiff/2025...
Reposted by Dave Bacon
Do you want to help develop new theories for systems that adapt, evolve, and interact?
Applications are open for SFI’s 2026 UCR program, a fully funded, 10-week experience for undergraduates, offering mentorship, seminars, and project development.
Apply by Jan 14, 2026
www.santafe.edu/ucr
Applications are open for SFI’s 2026 UCR program, a fully funded, 10-week experience for undergraduates, offering mentorship, seminars, and project development.
Apply by Jan 14, 2026
www.santafe.edu/ucr
December 25, 2025 at 6:02 PM
Do you want to help develop new theories for systems that adapt, evolve, and interact?
Applications are open for SFI’s 2026 UCR program, a fully funded, 10-week experience for undergraduates, offering mentorship, seminars, and project development.
Apply by Jan 14, 2026
www.santafe.edu/ucr
Applications are open for SFI’s 2026 UCR program, a fully funded, 10-week experience for undergraduates, offering mentorship, seminars, and project development.
Apply by Jan 14, 2026
www.santafe.edu/ucr
A pretty good haul.
December 25, 2025 at 11:34 PM
A pretty good haul.
Will recite this one before my next fencing bout.
I know my heart, I have gained power over my heart, I have gained power over my two hands and arms, I have gained power over my feet, I have gained the power to do what pleaseth my Ka. (BDB)
December 25, 2025 at 3:08 PM
Will recite this one before my next fencing bout.
This is a cool result, but to me represents why the Turing model is actually the wrong physics model of computing. This is because it is serial, and so cannot deal with errors. I’ve written about this here dabacon.org/pontiff/2010...
December 23, 2025 at 3:57 PM
This is a cool result, but to me represents why the Turing model is actually the wrong physics model of computing. This is because it is serial, and so cannot deal with errors. I’ve written about this here dabacon.org/pontiff/2010...
Reposted by Dave Bacon
My colleague Sanjay Ghemawat & I have done a fair bit of performance tuning of various pieces of code. We wrote an internal Performance Hints document ~2 years ago as a way of identifying some general principles & we've recently published a version of it externally.
Doc: abseil.io/fast/hints.h...
Doc: abseil.io/fast/hints.h...
December 19, 2025 at 10:25 PM
My colleague Sanjay Ghemawat & I have done a fair bit of performance tuning of various pieces of code. We wrote an internal Performance Hints document ~2 years ago as a way of identifying some general principles & we've recently published a version of it externally.
Doc: abseil.io/fast/hints.h...
Doc: abseil.io/fast/hints.h...
Reposted by Dave Bacon
Scientists should read this.
artificialbureaucracy.substack.com/p/context-wi...
artificialbureaucracy.substack.com/p/context-wi...
Context Widows
or, of GPUs, LPUs, and Goal Displacement
artificialbureaucracy.substack.com
December 16, 2025 at 6:09 AM
Scientists should read this.
artificialbureaucracy.substack.com/p/context-wi...
artificialbureaucracy.substack.com/p/context-wi...
And it’s actually even crazier than that (the epidemic stuff is the beginning). Wheelers four no’s include: self reference instead of hierarchy of laws, no laws, no continuum, no spacetime!
Seems to be a losing battle to make people understand that Wheeler's "It from Bit" does not mean "reality is made of information" (it was about defending an epistemic view of quantum mechanics, where the wave function isn't real, only measurement outcomes are), and likewise...
December 16, 2025 at 12:10 AM
And it’s actually even crazier than that (the epidemic stuff is the beginning). Wheelers four no’s include: self reference instead of hierarchy of laws, no laws, no continuum, no spacetime!
Reposted by Dave Bacon
Applications open for SFI’s 2026 UCR program.
Are you fascinated by transdisciplinary questions that transcend or combine disciplines? UCR is a fully funded, 10-week summer research experience for undergraduates curious about complexity science.
Apply by Jan 14, 2026
santafe.edu/ucr
Are you fascinated by transdisciplinary questions that transcend or combine disciplines? UCR is a fully funded, 10-week summer research experience for undergraduates curious about complexity science.
Apply by Jan 14, 2026
santafe.edu/ucr
December 11, 2025 at 10:04 PM
Applications open for SFI’s 2026 UCR program.
Are you fascinated by transdisciplinary questions that transcend or combine disciplines? UCR is a fully funded, 10-week summer research experience for undergraduates curious about complexity science.
Apply by Jan 14, 2026
santafe.edu/ucr
Are you fascinated by transdisciplinary questions that transcend or combine disciplines? UCR is a fully funded, 10-week summer research experience for undergraduates curious about complexity science.
Apply by Jan 14, 2026
santafe.edu/ucr
Reposted by Dave Bacon
OpenAI leadership are promoting a paper in Physics Letters B where GPT-5 proposed the main idea — possibly the first peer-reviewed paper where an LLM generated the core contribution. One small problem: GPT-5's idea tests the wrong thing. My technical comment: scirate.com/arxiv/2512.0... 1/
![As part of a broader effort to demonstrate AI’s po-
tential in scientific research [1], OpenAI executives have
pointed to a recently published paper by Hsu [2] as evi-
dence that AI can contribute original ideas to physics [3,
4]. Hsu credits GPT-5 with proposing the core idea of the
paper de novo, possibly the first published physics article
where the main idea came from an LLM, and discusses
the methodology in a companion piece [5]. We examine
whether GPT-5’s criterion is correct.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:uknpj5mh4cfutreceecdbv7x/bafkreia3jerjfcqdui45n4upaqci5u5r6st7o7pqmdzahhjtidtostpooq@jpeg)
December 9, 2025 at 5:17 PM
OpenAI leadership are promoting a paper in Physics Letters B where GPT-5 proposed the main idea — possibly the first peer-reviewed paper where an LLM generated the core contribution. One small problem: GPT-5's idea tests the wrong thing. My technical comment: scirate.com/arxiv/2512.0... 1/
Reposted by Dave Bacon
Great visit to Tufts a few weeks ago. They have an open-rank job in Quantum Information / Computing theory. Open Positions | Department of Physics and Astronomy share.google/NosuSUs77OZU...
Open Positions | Department of Physics and Astronomy
Below are job opportunities within the Department of Physics and Astronomy. For additional employment opportunities at Tufts University, please visit Careers at Tufts.Full-time Positions:
share.google
December 9, 2025 at 1:37 AM
Great visit to Tufts a few weeks ago. They have an open-rank job in Quantum Information / Computing theory. Open Positions | Department of Physics and Astronomy share.google/NosuSUs77OZU...
Reposted by Dave Bacon
A claim of indirect detection of dark matter via gamma rays from the galactic center. I would not get too excited until independent confirmation comes along; many people have looked for exactly this signal. It’s too easy to make gamma rays from more conventional sources.
This just in: a NASA telescope may have just "seen" #darkmatter for the first time! By exploring the Milky Way's galactic halo and using the latest data, a team of researchers detected high-energy gamma rays extending towards the center of the Milky Way. Find out more here: https://ow.ly/OJe550XE40B
December 7, 2025 at 12:35 PM
A claim of indirect detection of dark matter via gamma rays from the galactic center. I would not get too excited until independent confirmation comes along; many people have looked for exactly this signal. It’s too easy to make gamma rays from more conventional sources.
Don’t tempt me langjamgamejam.com
Langjam Gamejam
A 7-day challenge to create a programming language and then use it to build a game.
langjamgamejam.com
December 1, 2025 at 8:35 PM
Don’t tempt me langjamgamejam.com
Preprocessing direct in QEC microcode
May I guide the hearts of the gods, and may they protect me, may I be mighty among those who suspend themselves on high. (BDF)
November 26, 2025 at 3:24 PM
Preprocessing direct in QEC microcode
Bullshit is sort of the opposite of a problem in coNP. Instead of hard to find but efficient to verify it is false, it is easy to find and hard to verify it is false.
Who was it who said it takes 10x more effort to refute bullshit than to create it?
November 26, 2025 at 3:22 PM
Bullshit is sort of the opposite of a problem in coNP. Instead of hard to find but efficient to verify it is false, it is easy to find and hard to verify it is false.