Joined September 2012
- Tweets 1,555
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- Followers 578
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61 Photos and videos
Jun 5
Every day I see wallpaper patterns in the world and am glad I learned to recognize and name all 17 types.
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Mark Moon retweeted
May 23
periodic reminder that high-altitude lightning aka transient luminous events were seen for decades by pilots who kept quiet for fear of being labelled a nut, predicted by physicists for decades too, accidentally recorded only in 1989 when cameras were finally good enough.
periodic reminder that the upper atmosphere has red tendrils of hyper-lightning over 50 km tall
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May 21
Who's interested in joining a reading group dedicated to understanding OpenAI's new work on the unit distance problem?
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The (classically valid) Intermediate Value Theorem states that if a continuous function takes the values ā1 and 1, then it takes all values in [ā1, 1]. Let me try to give insight why this cannot hold as such in constructive math, even for a very innocent function. š§µā¤µļø ā¢1/29
![Graph of the function x ā¦ sup(inf(4x 1,0),4xā3) from [0,1] to [ā1,1]. It is continuous, order-preserving, maps 0 to ā1 and 1 to 1, and is constantly equal to 0 from āĀ½ to Ā½.](https://venexa.site/media/HHvVNV1W4AcHWFy.png)
ALT Graph of the function x ā¦ sup(inf(4x 1,0),4xā3) from [0,1] to [ā1,1]. It is continuous, order-preserving, maps 0 to ā1 and 1 to 1, and is constantly equal to 0 from āĀ½ to Ā½.
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May 1
A nice linear algebra problem came up when I was working on some matrix calculus problems with a student the other day: Suppose you have some fixed matrix X, and define the "multiply by X on the right" linear map from one vector space of matrices to another. What's the dual map?
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Mark Moon retweeted
Apr 23
From $100 to $600 is a 500% rise.
From $600 to $100 is an 83% savings.
This is elementary math, most all people in the room know it and should be embarrassed to their bones to go along with this North Korean style theatre
Apr 23
RFK Jr: "A Democratic senator claimed it's mathematically impossible to have a drug drop by 600%. I said, 'Well, if the drug was $100 and it raises to $600, that would be a 600% rise. If it drops from $600 to $100, that's a 600% savings.'"
Trump: "Right"
Community note
RFK Jr.'s example misstates percentage changes. From $100 to $600 is a 500% increase ((600-100)/100 Ć 100). From $600 to $100 is an 83.3% decrease ((100-600)/600 Ć 100). A 600% decrease from $600 would reach a negative price.
newsweek.com/rfk-jr-trump-dā¦
cnn.com/2025/09/23/polā¦
calculatorsoup.com/calculators/alā¦
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Apr 2
April update: I'm currently teaching category theory (Awodey), classical mechanics (Kleppner & Kolenkow), intro to proofs (Cummings), convex optimization (Boyd & Vandenberghe), and quantum mechanics (Shankar).
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Apr 1
<seinfeld voice>: anyone can *write* 37k lines of code
Absolutely insane week for agentic engineering
37K LOC per day across 5 projects
Still speeding up
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Mar 31
Reminder : the world record for the largest number legitimately factored by Shor's algorithm on a quantum computer is 15, 3Ć5, and that record was achieved in 2001.
Mar 31
BREAKING: Google research reveals quantum computers may be able to crack Bitcoin's private keys in just 9 minutes.
Community note
The 9-minute estimate in Google's research applies to theoretical on-spend attacks using future quantum computers that do not yet exist. quantumai.google/static/site-asā¦
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š½ So, Jean Abou Samra and I are please to announce a new preprint in computability, in which we show that the Turing degrees can be embedded upside down in (what we call) the āArthur-Nimue-Merlin degreesā.
The paper opens with a riddle, which I hope will be of interest!
![First page of the paper titled āAn order-reversing embedding of Turing degrees into ArthurāNimueāMerlin degreesā by Jean Abou Samra & David Alexander Madore, arXiv:2603.19946v1 [math.LO] 20 Mar 2026. Abstract reads as follows: Ā«The ArthurāNimueāMerlin degrees are a generalization of the Turing degrees introduced by Kihara as a tangible description of the partially ordered set of LawvereāTierney topologies on the effective topos (equivalently, subtoposes of the effective topos). They are defined in terms of a three-player game that introduces both angelic and demonic non-determinism into oracle queries. We construct an order embedding of the Turing degrees with their order reversed into the ArthurāNimueāMerlin degrees, whose image we call the āco-Turing degreesā; we then study the order relationship of these co-Turing degrees with the (naturally embedded) Turing degrees within the ArthurāNimueāMerlin degrees.Ā»](https://venexa.site/media/HEF-Y5qaMAA63u_.png)
ALT First page of the paper titled āAn order-reversing embedding of Turing degrees into ArthurāNimueāMerlin degreesā by Jean Abou Samra & David Alexander Madore, arXiv:2603.19946v1 [math.LO] 20 Mar 2026. Abstract reads as follows: Ā«The ArthurāNimueāMerlin degrees are a generalization of the Turing degrees introduced by Kihara as a tangible description of the partially ordered set of LawvereāTierney topologies on the effective topos (equivalently, subtoposes of the effective topos). They are defined in terms of a three-player game that introduces both angelic and demonic non-determinism into oracle queries. We construct an order embedding of the Turing degrees with their order reversed into the ArthurāNimueāMerlin degrees, whose image we call the āco-Turing degreesā; we then study the order relationship of these co-Turing degrees with the (naturally embedded) Turing degrees within the ArthurāNimueāMerlin degrees.Ā»
Mar 23
Jean Abou Samra, David Alexander Madore: An order-reversing embedding of Turing degrees into Arthur-Nimue-Merlin degrees arxiv.org/abs/2603.19946 arxiv.org/pdf/2603.19946 arxiv.org/html/2603.19946
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Mar 21
In honor of the equinox, here's a simple derivation of an accurate formula for the position of the Sun in the sky (at a given date and latitude): arxiv.org/abs/1208.1043.
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Mark Moon retweeted
Mar 18
Today my colleagues and I released a paper on the formalization of d=4 Quantum Field Theory in Lean. We believe that formal verification has the potential not only to radically reshape how mathematical research is conducted, but also to transform research in theoretical physics.
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Mark Moon retweeted
Mar 16
I had a $600,000 over 5 years NSF Physics grant terminated last year because our grant mentioned "polarization" which was included in the banned terms list. We were discussing the polarization of light. We never got the grant reinstated.
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Mark Moon retweeted
Mar 5
My Fellow Shakespeareans - Iāve recorded all 154 Sonnets for my latest project, āPatrick Stewart Performs the Complete Sonnets of William Shakespeareā.
This special audio production is available to listen to April 7.
Preorder now: audible.com/pd/Patrick-Stewaā¦
@SimonAudio
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Mar 3
March update: I'm currently teaching category theory (Awodey), classical mechanics (Kleppner & Kolenkow), group theory (Dummit & Foote), and intro to proofs (Cummings).
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Mark Moon retweeted
Feb 25
g ā ĻĀ² is not a coincidence.
The original idea for the definition of ā1 meterā was the length of a pendulum with a half-period of 1 second.
The formula for a pendulumās period is:
T = 2Ļ ā(L / g)
If you plug in L = 1 m and T = 2 s, you get g = ĻĀ² m/sĀ².
The actual definition of ā1 meterā was eventually chosen as 10ā»ā· of a half-meridian passing through Paris, but this was inspired by the earlier pendulum-based definition. The two definitions agree to within 1%.
Feb 25
ĻĀ² is approximately equal to Earthās gravitational acceleration, 9.807 m/sĀ².
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Feb 26
So far, teaching classical mechanics is a lot like teaching a typical math class: every 5 minutes I get to pause and say "Much of this was first worked out by Euler, of course.".
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At this point, Iāve sent this brilliant neat little color matching game to all my computer vision and graphics friends. As someone who thrives on visual stimuli and pattern recognition, Iām completely obsessed with it!
dialed.gg/
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