Yann LeCun

I do not write posts on X. I tweet links to posts on other platforms. I like and retweet (occasionally) I comment on friends' tweets (rarely) Follow me on...⬇️⬇️⬇️

Trump cut federal funds for health insurance and food assistance for the needy, but he is now asking for $200 billion in new funds to finance his war-of-choice crime of aggression in Iran. trib.al/2dWfYrY

We’re hiring ! x.com/i/jobs/2034564…

Yann LeCun and his team dropped yet another paper! "V-JEPA 2.1: Unlocking Dense Features in Video Self-Supervised Learning" In this V-JEPA upgrade, they showed that if you make a video model predict every patch, not just the masked ones AND at multiple layers, they are able to turn vague scene understanding into dense + temporal stable features that actually understands "what is where". This key insight drove improvements in segmentation, depth, anticipation, and even robot planning.

physical systems (orbits/fluid mechanics) may look complex, but are often governed by simple equations/few parameters. can current self-supervised methods learn the underlying physics? our new paper finds that learning in latent space may be the key! arxiv.org/abs/2603.13227🧵

Kilopower, the little Martian reactor that could: A miracle of simplicity & sodium. NASA was given the brief to design a super-simple micro-reactor for future Martian settlement, and it did so brilliantly by doing it unconventionally. A normal Earthbound nuclear reactor is complex, with banks of pumps, water & steam injection pressurizers, control rod actuation, frequent movement of fuel during refuelling cycles, complex systems of valves, back-up emergency coolant and deluge systems, boron injection… it goes on & on & on. A terrestrial nuclear plant is a triumph of safety-conscious system engineering, but it’s a busy one, and Kilopower dispensed with all of this. The intention for the system is that you could set it up, get it started and just… forget about it, pretty much. It has a small, solid core with no moving pieces except for the control rod which is designed to be moved on startup and then kept in place, unmonitored, for a decade at a time. The small size & low power means that reactivity effects are dominated by thermal expansion and are extremely stable. Low power designs (less than 100 kiloWatts thermal energy) make thermal management and irradiation damage a non-issue that does not complicate system design. Very low power level designs (less than 10kW thermal) feature such low burnup reactivity that movement of the control rod becomes a ten-year interval. A literal ‘tin’ wedding anniversary, marked out by tweaks to the control rod. There’s a quirky Martian anniversary gift for you! Even at much higher power levels, the stability is such, and burnup so low, that control rod movement would be something you’d only have to do occasionally, every few months or annually. In essence this is a nuclear battery. In all cases, the reactor is designed to handle worst-case transients such as coolant loss passively without any need for control inputs, further simplifying the system. Truly, this is a zen ideal: Feng Shui engineering, where less is more and the system simplicity brings reliability and safety, all in one. Perfect for missions to space.

A three-year-old company operating out of a WeWork with reportedly fewer than five employees is being considered for up to $25 BILLION in nuclear energy funds from a trade deal Trump brokered with Japan. The company has never built a nuclear plant or completed a nuclear project of any kind. What does this company bring to the table? The father of its CEO donated $2 million+ to Trump and the GOP, and one of its advisors is a former RNC co-chair and Trump appointee. In this Administration, that’s apparently all you need.

Anne Applebaum nails it:

Grateful for what, exactly? Let Mr. Hegseth count the ways. 1.Abandoning Ukraine mid-war 2.The Greenland annexation fantasy 3.Tariffs on allies who still answer the phone 4.A defense secretary with no defense experience 5.Withdrawing from the Paris Agreement. Again. 6.Gutting USAID while calling it efficiency 7.The trade war with Canada 8.Recognizing Crimea as Russian territory 9.Pulling out of the WHO during a health crisis 10.Threatening to leave NATO 11.Cosying up to every autocrat with a decent golf course 12.The collapse of US soft power in under 90 days 13.Alienating the EU faster than Brexit managed 14.Signal-gating classified war plans to a journalist 15.Deploying the military to arrest migrants at the border 16.Defunding public broadcasting 17.Handing Elon Musk the keys to federal spending 18.Ending birthright citizenship by executive order 19.Firing the inspectors general who were watching all of the above 20. And now – a war in Iran nobody asked for, going exactly as well as you’d expect You’re welcome, world. Gandalv / @Microinteracti1

.@AdamSerwer on how Trump’s “America First” principles landed us in a war with no obvious end and no allies willing to help us. theatlantic.com/ideas/2026/03/…

us fallen back to democracy levels of the 1960s

The Iran war is going so bad for Trump right now he might need to release The Epstein Files as a distraction.

Tired of winning

BREAKING: Fed Chair Powell says U.S. private sector job growth is essentially ZERO “Golden age”

How can anybody consider Trump sane enough to be US president?

The Freedom House report “Freedom in the World 2026” has just been published, and its findings will surprise no one. freedomhouse.org/sites/default/…

This is unhinged. The President of the United States went on a late-night rant, making clear he believes the Supreme Court justices he appointed owe him their loyalty and should always rule in his favor. The President of the United States is openly attacking the independence of the judiciary, the very institution that stands between every American and unchecked executive power. Courts don’t work for the President. They work for the Constitution. And a president attacking the judiciary for doing its job is telling you he believes he is above the law.

The U.S. job market is the worst in decades. And the main cause of this is completely incompetent government.

1/ New paper from @ylecun et al on alternative approach for AI to learn more biologically... paper basically says AI is super smart but still can't learn like a toddler can... the main critique

🚨𝘽𝙍𝙀𝘼𝙆𝙄𝙉𝙂: European Commission President Ursula von der Leyen unveiled EU–INC, a new framework that lets you launch a company in 48 hours for under €100 Starting a company across the EU today = 27 legal systems, 60+ company structures 🤯 That might be about to change… The European Commission just introduced 𝗘𝗨 𝗜𝗻𝗰., a new optional corporate framework designed to make Europe actually function like one market. Here’s what stands out: → Set up a company in 48 hours → Cost: < €100 → Fully online, no minimum capital → One single framework across all EU countries → Easier share transfers & fundraising → EU-wide employee stock options (huge for talent) Especially the EU-wide stock option plans, taxed only when employees actually sell (instead of when granted) is huge. This makes it far easier for startups to attract and retain top talent, finally putting Europe closer to the US playbook. Source/More info: ec.europa.eu/commission/pre… In short: This is Europe trying to compete with the simplicity of a Delaware C-Corp 🇺🇸 And honestly… it’s long overdue. For years, European founders had 2 choices: 1. Stay local and deal with fragmentation 2. Move to the US to scale 𝗘𝗨 𝗜𝗻𝗰. is trying to remove that trade-off. If executed well, this could be one of the most important structural changes for European startups in decades. What do you think?

Not a huge impact from Iran yet, but a new net low in our Trump approval tracking today fwiw.