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...⬇️⬇️⬇️

The Well Just Dropped: 15 Terabytes of Pure Physics Gold Is Now Open Source The scientific AI world just got a massive upgrade.Polymathic AI, in collaboration with the Flatiron Institute and researchers from Princeton, Cambridge, NYU, Berkeley, Los Alamos, and more, has released The Well: a staggering 15TB collection of high-fidelity physics simulations. This isn’t toy data. These are real, expensive-to-run simulations across 16 different physical domains, including turbulent fluid dynamics, supernova explosions, magneto-hydrodynamic cosmic flows, acoustic scattering, and active biological matter. Until now, reproducing this level of data required weeks on national supercomputers and grant money most teams will never see. The Well changes everything. It’s purpose-built for training PDE surrogate models the AI systems that can replace slow, costly physics solvers with a single fast neural network forward pass. Everything is fully open source, easy to load with PyTorch, and ready to drop straight into your training pipeline. Researchers and builders can now train on world-class physics data without the insane compute barriers that used to stand in the way. This is more than just another dataset drop. It’s a serious accelerator for scientific machine learning.The future of physics-informed AI just got a whole lot more accessible.Get it here: polymathic-ai.org/the_well/

@AriDotnow @KenRoth I worked at AT&T Bell Labs from 1988 to 1995, the AT&T Labs-Research from 1996 to 2002. Xerox, AT&T, IBM, Microsoft, plus Meta and Google until recently, could afford advanced research labs because they were de facto monopolies.

@ylecun @KenRoth weren't bell labs and xerox the best most innovative places?

Trump’s cuts in funding for higher education is reducing the number of PhD candidates and “raising fears that the nation’s capacity to produce new science could be diminished.” trib.al/TzuHUm6

@d_comfe Approved 😁

I am coining a new word - Yanntificate. To espouse and communicate sensible AI policy.

@Plinz @skinnybobinfo @MarkWarner @Kasparov63 It was a abysmally incompetent coup attempt. But it was a coup attempt.

@skinnybobinfo @ylecun @MarkWarner @Kasparov63 While I think that the administration represents rock bottom and does not bode well for the future of US democracy, I don't think you can perform a coup by letting some hillbillies walk through a public building. You need a military takeover. Jan 6 being a coup is a BluAnon meme.

Reports that the White House has dismissed the remaining members of the Election Assistance Commission — all of whom were unanimously confirmed by the Senate, including a commissioner appointed by President Trump himself — should concern every American, regardless of party, because the EAC was established by Congress as an independent, bipartisan body to help states administer secure and credible elections. If these reports are accurate, removing every remaining commissioner just months before the 2026 midterm elections is an extraordinary step that demands an immediate explanation from the administration and raises profound concerns about political interference in the institutions that support our elections.

All foundation models are in fact models of knowledge, mainly based on open knowledge already developed by mainkind. Obviously knowledge (models) of mankind should be open sourced! (Again, please do not confuse knowledge with intelligence.)

History has seen this movie before. 1880s Late Imperial Russia: Fear of dissent led to tighter control over universities. That alienated students and scholars, weakened trust in the state, and produced more dissent. 1930s Nazi Germany: Fear of disloyalty led to purges, banned ideas, and loyalty tests. That drove out talent, weakened universities, and made the regime even more dependent on loyalty over truth. 1960s China’s Cultural Revolution: Fear of independent thought led to attacks on teachers, schools, and universities. The result was an entire Lost Generation. The spiral: Fear brings control. Control drives out talent. Lost talent weakens education. Weaker education weakens the state. A weaker state becomes more fearful—and tightens control again.

This is total insanity. Words fail to explain how anyone let alone a plurality of voters thought giving an obviously demented person control of the most powerful government in the world was a good idea. We will be lucky to come out the other side of this alive.

outstanding essay from Seb: "A cadre of elites decides which research directions are permissible, caps global compute and robotics, and creates state-administered scarcity rents. I shouldn’t need to explain why this is bad and dangerous, anyone can study History and Economics in their free time. [...] Building an entire apparatus tasked with maximally empowering the government and its grip on research, knowledge, and technology is dangerous." Read every word of it 👉

Donald Trump is mentally deranged. He’s a danger to the U.S. He’s a danger to the globe. He does not belong in this position of power—in control of the massive U.S. military—and he should be removed from office. This is not a joke. And his GOP enablers are responsible for abdicating their duty.

AI 2040 and other similar policy proposals for dystopian AI control are evil. If I had the time machine in Terminator, I would send every one of these people back in time to live in Stalin's Russia, or Mao's China, or Berlin with the Wall and then bring them back after a year cured of their stupidity. Let's just make it clear. As Ramez says, the proposal warns against centralization of AI by proposing radically dangerous authoritarian surveillance powers that are infinitely more dangerous than the fake danger they propose to defend against. We've reached a point where people who spent too much time huffing glue and reading Dune or watching Terminator and thinking it was a documentary are now proposing some of the most dangerous and horrific policies imaginable. They must be stopped from infecting politicians with this kind of logic disease. Their policies cannot be taken seriously unless you have no sense of history, no sense of the actual dangers of history, no sense of what handing draconian powers to governments will do to a society, and frankly, no critical thinking ability or self awareness whatsoever. I don't care that the "authors mean well." Dunning Kruger policies get no pass from me because someone means well.

So military troops under the direct control of Trump and Hegseth will be on the streets of our nation’s capital for the rest of Trump’s term. The rationale—they’re here to help with a crime emergency—is laughable. But of course the real reason is ominous. cbs4local.com/news/nation-wo…

As I wrote a year ago, watch the actions of the Trump admin through the eyes of someone who has watched democracy turn into autocracy. Centralizing election authority, expanding federalized troops and putting them in the streets, cracking down on the press. It's not original.

If you wished @suno offered finer controls for music production, you can now pipe its songs through MuScriptor and import them in your favorite DAW 🎹

An embarrassed Trump falsely claims that his shocking $2.2 billion in revenue in 2025 came from the stock market when it mostly came from his sleazy cryptocurrency dealings. trib.al/TNSg9lb

Music is missing its "openai-whisper". It's time that we can turn any music into notes, the same way transcribing speech is now a given. Are we there yet? Let us know after testing MuScriptor 🎶 Work by @simonrouard (@kyutai_labs, @Ircam) and Michael Krause (@MireloAI).

@kyutai_labs @MireloAI Awesome stuff 👍 Congrats 👏👏👏

We're releasing MuScriptor, the best open model for multi-instrument transcription to date, created in collaboration with @MireloAI. Give it a recording in any genre: pop, classical, metal, jazz, whatever, and it transcribes the individual instruments into MIDI. Link in 🧵

We stand at a critical crossroads in the debate over AI governance in the United States, and it feels like we are inching closer to a very serious battle over whether or not open source models will even be allowed in an environment where a new de facto licensing regime has been taking shape. Lacking formal congressional statutory frameworks or clear administration rules (like the diffusion rule revision), we appear to be left with a sporadic, arbitrary, non-transparent process for model review. The fiction of “voluntary” agreements hangs over this debate, and some large model developers are already showing an incredible willingness to bend over backwards to accommodate national security-related officials / orders that the rest of us are not privy to. It's a very opaque process. And those model developers are expected to play ball with those officials, or else their models get pulled from the market or held up for long periods. Or they will lose any government procurement contracts they have. There is nothing “voluntary” about it when that Sword of Damocles hangs in the room. As this mess worsens, at some point the question of how to handle open source models will come into sharper focus because it will have to. I've even heard some rumors lately that something may be coming from the admin on this front to address this. Needless to say, if this informal new AI model review regime expands and takes on more pre-vetting characteristics / requirements, it is hard to see how open source players could comply with such quasi-licensing of AI models. Specifically, if this ambiguous new regime is accompanied by a general presumption of ‘restrict-until-permitted,’ then that would spell doom for open source. That is a very dark path for our country. Worse yet, of course, would be a move by national security officials to more directly restrict open source models and capabilities. If that happens, then we would be right back in the thick of a Clipper Chip-like battle along the lines of what we saw in the late 1990s. That is a much darker path for America. Meanwhile, open source developers have no “golden shares” or other goodies to offer the government to make their problems go away. Let’s be clear: If our government takes the dark path, it will become the single most important battle over computational freedom of modern times. It is time for people to make a stand in defense of open source before it is too late.

Today, together with @kyutai_labs, we’re introducing our new Audio-to-MIDI model. It takes a finished recording, identifies the instruments playing, and returns separate MIDI tracks for each — voice, drums, bass, keys, and more. Unlike most existing solutions, our model works directly from the full mix rather than requiring separate stems. It also detects chords, key, and tempo, giving producers broader musical context. We’ve written more about the model, the problem, and how it works here: mirelo.ai/blog/turning-a…