Reposted by GregorGregor @coexact.bsky.social · 30/08/2026let me try to explain. As everyone knows from kindergarten, a massless fermion comes with a definite chirality and a mass term for a fermion is a bilinear coupling between two such of opposite chiralities (a Majorana is the special case where they are each others antiparticle). 131
Gregor @coexact.bsky.social · 28/05/2026This is a nice discussion with points that I am largely sympathetic to. I have some thoughts on the conclusions drawn at the end about the emergence of time—though these matters are so uncertain that it's impossible for me to have any tightly-held conviction. Nevertheless: 141
Gregor @coexact.bsky.social · 28/05/2026still dropping bangers!youtube.comHolograms and their Standard Models: DSSYK_∞ and the ‘t Hooft Model - Leonard SusskindYouTube video by Institute for Advanced Study 052
Gregor @coexact.bsky.social · 10/05/2026I wrote a blog post about quantum reference frames, energy conservation and also gravitycoexactly.github.ioKeeping Time and Energy in Closed SystemsClocks, energy, and the problem of time in closed quantum systems. 183
Gregor @coexact.bsky.social · 16/04/2026The existence of reginos implies the existence of their supersymmetric partners: regions 050
Gregor @coexact.bsky.social · 05/04/2026thread with random things found in my grandparents' apartment. A distorted mirror 110
Gregor @coexact.bsky.social · 05/04/2026it's cool that 'gravity is non-local magic' seems to be an accurate description according to the state of the art 140
Reposted by GregorQuOI Theory @quoi-theory.at · 01/04/2026A new, very serious preprint is out from Veronika and Alberto. No, don't look at today's date it's 100% legit we promise. It's a genuine proof that P=NP... (...if you believe in quantum many-worlds and are willing to destroy almost every observer in the multiverse 👀) arxiv.org/abs/2603.28869 1163
Gregor @coexact.bsky.social · 26/03/2026this fact is my downfall—my pathology is I will still tag myself ':)' 030
Reposted by GregorSophie Huiberts @sophie.huiberts.me · 03/03/2026It's been almost two years and still I hear of people calling my IPCO lecture a scandal 😊youtu.beOpen Problems & Diet ProblemsYouTube video by Sophie Huiberts 181
Gregor @coexact.bsky.social · 21/02/2026so I just realized the very obvious fact that if I can apply a noise removal filter to my mic input in calls, I can also apply it to any other audio stream and poorly recorded video lectures just got so much more pleasant 030
Gregor @coexact.bsky.social · 08/02/2026this is what we have the renormalization group for Goku is just at a critical point 041
Reposted by Gregor4gravitons.bsky.social @4gravitons.bsky.social · 05/02/2026Physicists of Bluesky! I'm looking for a specific type of story from the early days of cyclotron research, for a piece for @physicstoday.bsky.social . Have you heard tales of scientists who aligned beams with the naked eye? Know an older physicists who has? Let me know! 131
Gregor @coexact.bsky.social · 04/02/2026for those unaware, this feed is extremely cool & useful & good! 020
Gregor @coexact.bsky.social · 29/01/2026You've heard of Solomon Lefschetz, but did you know he had an evil twin? We just call him perverse weak Lefschetz, he proved the perverse weak Lefschetz theorem 130
Reposted by GregorGro-Tsen @gro-tsen.bsky.social · 13/01/2026Here's a mathematical fact which I find amazingly counter-intuitive: There exists a polytope (=the convex hull of a finite set) in ℝ⁴ which is not combinatorially equivalent to one with rational vertex coordinates (=the convex hull of a finite subset of ℚ⁴)! 🤯 •1/4 3265
Reposted by GregorSarah Z @sarahz.bsky.social · 06/01/2026In a strange position where I think there are massive, massive social harms to the proliferation of AI (misinfo, deepfakes, predatory 'companions', surveillance, labour rights) but also feel the mainstream arguments against it range from unconvincing (water) to actively harmful (copyright; "soul") 39983277
Gregor @coexact.bsky.social · 23/12/2025kinda interesting story here. Can a LLM with some vibecoded framing produce a decent index for a book? I confess I wasn't aware of indexing as a profession prior to this, but even without leaving this site you can find the tail end of a community, with orgs, conferences, meetups.. 110
Gregor @coexact.bsky.social · 22/12/2025no matter how you slice it, if intelligent life survives all other hurdles, it will eventually end for astrophysical reasons, be that the expansion of the sun or cosmic heat death. It will be like climate change but worse: much slower, much more predictable, not preventable, hopelessly unsurvivable 120
Gregor @coexact.bsky.social · 22/12/2025to point at an elephant, it is incredibly obvious that the long-term global "cost" of basically ending extreme poverty is super-duper negative 020
Gregor @coexact.bsky.social · 22/12/2025Have known the evenings, mornings, afternoons, I have measured out my life with coffee spoons (TS Eliot) (The power was out at the NIST atomic clocks, presumably) 020
Gregor @coexact.bsky.social · 17/10/2025If you've ever wanted to actually watch a laser beam bounce through a light clock, AlphaPhoenix just dropped the most incredible videoyoutube.comThis is what the speed of light looks likeYouTube video by AlphaPhoenix 121
Reposted by GregorCraig Gidney @craiggidney.bsky.social · 31/08/2025Been awhile since I wrote a blog post. Anyways... why haven't quantum computers factored 21 yet? algassert.com/post/2500algassert.comWhy haven't quantum computers factored 21 yet?Craig Gidney's computer science blog 56513
Reposted by Gregor🇵🇸Tim Henke (tɪm 'ɦɛŋ.kə) @timhenke.bsky.social · 13/08/2025THREAD: Resurgence or: How do physicists keep getting away with ignoring infinitely big things? I wrote about this back when everyone was still on twitter. Someone asked me a question and I think it's an excellent occasion to repost the thread. 1/20 3308
Gregor @coexact.bsky.social · 03/08/2025obsessed with this prediction of 2025 by a 1999 4th-grader; I've read it so many times and it's complete poetry 050
Gregor @coexact.bsky.social · 16/07/2025Natural bundles are those associated to the frame bundle; spinor bundles are supernatural 072
Gregor @coexact.bsky.social · 20/06/2025thought about this again recently and have a picture I'm satisfied with, I think. Suppose at some spacetime pt there is a spontaneous nucleation of a decay to a new Lorentz-symmetric vacuum. This spreads out in a bubble at the speed of light and inside the bubble there must be some hot state to 110
Gregor @coexact.bsky.social · 31/05/2025Aaron Swartz should Also have been granted unfettered access to JSTOR tbc. Weird twisting going on here. Pls don't go to bat for academic publishers bc you don't like AI 020
Gregor @coexact.bsky.social · 26/05/2025lmao at one pt the startup CEO guy says that soon datacenters will cause '10-15 degrees of global warming', not bc of fossil fuels but bc they just pump out heat by themselves guess we've found the magical energy source of the future: datacenters 010
Gregor @coexact.bsky.social · 20/05/2025I am apparently just going to be miserable & stressed this week until I manage to Do the Task 000
Gregor @coexact.bsky.social · 19/05/2025my apartment has been getting cleaner today, which is unrelated to the hypothetical existence of any pressing unpleasant tasks that I could be taking care of 010
Gregor @coexact.bsky.social · 17/05/2025just went to the optician and it turns out my vision has worsened by a full diopter in the last year oops 010
Gregor @coexact.bsky.social · 09/05/2025I've always nodded through the stimulated emission part of how lasers work but it's actually a bit strange huh 210
Gregor @coexact.bsky.social · 03/05/2025Anyone know exactly how these images depict elliptic curve isogenies? Apparently the sixth one is inseparable but what precisely am I looking at? 062
Gregor @coexact.bsky.social · 13/04/2025this is what a global field of positive characteristic looks like btw 040