⚛️🧪 If you don't like tree level Feynman diagrams for phi-cubed theory you can just

Pauli once told von Neumann the result of a difficult physical problem and how he had arrived at it. Von Neumann replied that the same result could be derived from just one axiom. Pauli responded, 'Herr von Neumann! If physics could be done with axioms, you'd be a great physicist!' ⚛️🧪

The man who ensured Einstein never won a Nobel prize for relativity was an eye doctor. Ironically, he ended up making an important contribution to Einstein’s theory. This is the story of Allvar Gulstrand ⚛️🧪 nirmalyakajuri.substack.com/p/einsteins-...

The man who ensured Einstein never won a Nobel prize for relativity was an eye doctor. Ironically, he ended up making an important contribution to Einstein’s theory. This is the story of Allvar Gulstrand ⚛️🧪 nirmalyakajuri.substack.com/p/einsteins-...

In 1939, Einstein wrote a paper which claimed that black holes cannot form. Even though his own theory of general relativity predicted their possibility, Einstein believed that they were bugs of the maths, not features of the world. In this paper, he set out to prove it. 🧵⚛️🧪

I wrote up a small observation I had on the interplay between symmetries and state-dependent operators. arxiv.org/abs/2604.03003

New preprint, with my students Arundhati Goldar and Rhitaparna Pal! We extend Grinberg-Maldacena's result that the boundary thermal one-point function encodes the bulk geodesic distance from boundary to singularity in AdS black holes, to 3D de Sitter black holes. arxiv.org/abs/2603.21425

My students printed out my General Relativity lecture notes from a few years ago and made this cover for it!

*Takes the tiniest possible bite* "That's a big bite!" If I didn't read the description, I would have thought this was a comedy skit

Me: solve the equations x+y=5, x-y=3 Chatbot: (thought for 17 minutes) Simultaneous equations can be tricky. The equations you want solved are x+y=5, x-y=3. If we substitute x=z, y=w, the equations simplify to z+w=5, z-w=3. The next step would be to solve it. Just say the word. 1/3

Special relativity does not rule out faster-than-light signals? There's a strong argument showing that it need not. Hat tip to @uberwensch.bsky.social who shared a paper and initiated a discussion that inspired this post nirmalyakajuri.substack.com/p/faster-tha...

Thinking about hanging this clock in my office to remind me of the problem of time in canonical quantum gravity

There's so many physicists here on Blusky yet I never see any real discussion or dialogue on any physics topic despite following the physics feed and every physicist in my areas of interest. Am I missing them? What can we do to spark some physics conversations? ⚛️🧪

Ravi Vakil on learning mimetically from seminars. The backfilling part is my favorite--it feels like a blurry picture finally coming sharply into focus!

Just a tiny croc sunbathing in my office

From Akshita Mittal: Can a sneezing ant destroy a black hole? Regge and Wheeler set out to find out. ⚛️ 🔭 ☄️ 🧪 astrobites.org/2026/02/18/w...

Drinking game for high energy physicists: While checking arXiv, take a shot whenever you encounter one of these terms Unparticles Chameleons Fakeons Spurions WIMPzilla Axions Relaxions Dark Photons Fuzzball Galileons Curvatons Ghost Condensate Cuscatons Fractons ⚛️🧪

Here's a fun fact you can use to break the ice at parties. Whether a point is inside a black hole horizon or not depends on the entire future of spacetime. You're welcome. ⚛️🧪

Can a black hole replace the Large Hadron Collider? Rapidly rotating (Kerr) black holes can accelerate particles to enormously high energies., provided the particles have finetuned values of angular momentum. It can dwarf any accelerator on earth! But.. 1/3 ⚛️🧪

An important skillset for physicists is the mastery of computational techniques. With the advent of AI, this particular skillset looks like the first to be replaced. Wonder what this will mean for the the subset of physicists for whom this was the primary skillset. 🧪⚛️

Very cool! The field of scattering amplitudes involves working with massive algebraic expressions and finding patterns in them. Which is exactly the sort of thing AI is great at. Expect AI to become indispensable to this field. ⚛️🧪

You may have heard that spacetime is geometry, but what if I told you that even Newton’s laws are geometric? Newton’s laws say: if you tell me position and momentum of a system now, I can figure what they will be at any future point by solving equations given by Newton’s laws.. 1/4 ⚛️🧪

Physicist Ivette Fuentes turned down Epstein money: "The dream of my life is to build a gravitational-wave detector..So, if someone were to say to me, ‘I'll give you the money to make your dream come true,' it would be very tempting to say yes. But then you have your ethical standards." ⚛️🧪

Average PhD in Amplitudes ⚛️

Ed Witten, the journalist? ⚛️🧪

Campus looking good these days (photo by Munna Kumar)

Is that particle physics in your pocket or are you just happy to see me 🧪⚛️

As an ADHD-haver, AI helps me reduce the activation cost of starting tasks. Say I need to check for mistakes in a long computation. I let AI have a look, then check its report. After a bit of back and forth, I know where the mistakes might be. At that point I'm ready to dive in. ⚛️🧪

Anyway, like all the best physics analogies, you can express Nambu's illustration of spontaneous symmetry breaking via emoji. ⬅️↘️⬆️↖️⬇️ ↘️↖️⬆️⬅️↖️ ⬅️⬆️↙️↘️↖️ ↗️⬆️↘️➡️↖️ ↙️⬇️➡️↖️⬆️ vs ➡️➡️➡️➡️➡️ ➡️➡️➡️➡️➡️ ➡️➡️➡️➡️➡️ ➡️➡️➡️➡️➡️ ➡️➡️➡️➡️➡️ (8/8)

My top five "more people should look into that" topics in my field (theoretical high energy physics): 1. String duals of gauge theories 2. Stochastic quantization of gauge theories 3. Phase space methods in QFT 4. String field theory 5. Schwinger's action principle What is your list? ⚛️🧪

My top five "more people should look into that" topics in my field (theoretical high energy physics): 1. String duals of gauge theories 2. Stochastic quantization of gauge theories 3. Phase space methods in QFT 4. String field theory 5. Schwinger's action principle What is your list? ⚛️🧪

Physicists be like ⚛️🧪

What was the most interesting development this year in your research area? In holography, my vote would go for this and (even more) the subsequent baby universe debate. www.quantamagazine.org/cosmic-parad... ⚛️🧪

Steve Hsu predicts that in the next 15 years, AI will take Ed Witten's place as the oracle figure ⚛️🧪

What are the prospects of AI in physics? Will it generate more progress, or more noise? I sat down with two physicists, Stephen Hsu and Jonathan Oppenheim. Steve is an optimist while Jonathan is 'curmudgeonly' about AI. The discussion was fascinating! ⚛️🧪 www.youtube.com/watch?v=BRuD...

Recently, a physics paper whose central idea came from AI was published in a peer reviewed journal. How good is AI as a physicist? Is it time for us to hang up our boots already? I got in the absolute weeds to find out ⚛️🧪 nirmalyakajuri.substack.com/p/ais-first-...

Recently, a physics paper whose central idea came from AI was published in a peer reviewed journal. How good is AI as a physicist? Is it time for us to hang up our boots already? I got in the absolute weeds to find out ⚛️🧪 nirmalyakajuri.substack.com/p/ais-first-...

New Post! Multiverse is the one physics idea that broke confinement and exploded into popular consciousness. But if you only know of the multiverse from Marvel movies, it will come as a surprise that there isn’t just one multiverse in physics, but three.. ⚛️🧪 open.substack.com/pub/nirmalya...

Gave Chatgpt some tedious physics computations to do. It returned the right answer but complained just like a real student: "This is straightforward but tedious." "I grinded through the algebra." AGI confirmed

I tried looking back at the good old days, but all I saw was lockdowns and sourdough breads. I guess hindsight really is 2020.

How often do you find yourself wishing for a newsletter that covered fundamental physics in way that was accessible but not dumbed down? Pretty often, I am sure! Well, here it is. My free newsletter--"The Spacetime Beat". Enjoy! nirmalyakajuri.substack.com ⚛️🧪

Congratulations @jfdonoghue.bsky.social! Most well deserved. ⚛️🧪

"My taxes fund your 🧪 research, I will decide what you work on" MAGA_Rob37 my good man first of all I work in India. Pretty sure your taxes don't fund my research. Second of all I have no funds can you actually send some

"My taxes fund your 🧪 research, I will decide what you work on" MAGA_Rob37 my good man first of all I work in India. Pretty sure your taxes don't fund my research. Second of all I have no funds can you actually send some

"Black holes give off the impression of being dark and brooding, absorbing all the light around them. But they are secretly musical." I wrote about the music of black holes in my latest post. 🧪⚛️ open.substack.com/pub/nirmalya...

The 2025 Nobel Prize in Physics goes to John Clarke, Michel Devoret, and John Martinis — “for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit.” Here's what I understand of their work ⚛️🧪🧵

Why are there so many books on pop science 🧪 but so few on pop (academic) philosophy ?

AI will never be as smart as humans I say while making yet another decision prompted by algorithms

What counts as a quantum measurement? ⚛️

The existence of Ringo Starr implies the existence of ringing black holes. ⚛️🧪