Max Tegmark: MIT Physicist Who Wants the AI Race Slowed

Max Tegmark is a physicist at the Massachusetts Institute of Technology (MIT). He co-founded the Future of Life Institute (FLI), which published the 2023 call to pause giant artificial intelligence (AI) experiments. Through FLI, he backed a demand that AI labs pause training systems more powerful than GPT-4. His MIT professorship is on record, but the letter had documented signature problems, and his AI argument is disputed.

What Max Tegmark Is Known For

Max Tegmark is a physics professor at MIT and co-founder and chair of FLI. He is also the author of two books, and he put his name to FLI's 2023 pause letter. On AI, he argues the race should slow through a public, verifiable pause that includes all key actors.

His MIT Position and Field

MIT lists his title as exactly "Professor of Physics," as of November 2024. The listing shows no AI-specific title and no named or endowed chair. MIT lists his research areas as "Biophysics and Astrophysics Theory" and describes his work as "linking physics and machine learning: using AI for physics and physics for AI."

He joined MIT's department of physics in 2004. Wikipedia lists his fields as "Cosmology, physics, machine learning." His MIT affiliations include the MIT Kavli Institute for Astrophysics & Space Research and Physics of Living Systems @ MIT. His own lab is listed as the "Tegmark AI Safety Group." So his own research uses AI, and his lab carries the AI safety name.

His education, as Wikipedia records it, was:

• A B.A. in economics from the Stockholm School of Economics, in 1989
• An M.S.E. in engineering physics from KTH Royal Institute of Technology, in 1990
• An M.A. in physics from the University of California, Berkeley, in 1992
• A Ph.D. from the University of California, Berkeley, in 1994, supervised by Joseph Silk

Books and the Mathematical Universe

Tegmark wrote Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (Knopf, 2014) and Life 3.0: Being Human in the Age of Artificial Intelligence (Knopf, 2017). He first set out his mathematical universe hypothesis in a 1998 Annals of Physics paper, "Is 'the Theory of Everything' Merely the Ultimate Ensemble Theory?" He developed it in "The Mathematical Universe" in Foundations of Physics in 2008. The hypothesis is a physics question, separate from his AI work, and Wikipedia's entry on it sets out the papers and the replies to critics.

Future of Life Institute and His Title

Tegmark co-founded FLI with Anthony Aguirre, a professor at the University of California, Santa Cruz. Wikipedia records FLI's stated mission as steering "transformative technologies away from extreme, large-scale risks and towards benefiting life." For more on the group, read our explainer on the Future of Life Institute.

FLI's own people page lists Tegmark as "Founder and Chair" in its board section. The same page lists Aguirre as president and chief executive officer (CEO). Wikipedia calls Tegmark FLI's president and lists Aguirre as executive director. Older write-ups also call Tegmark FLI's president. Sources differ on the title, so this explainer uses FLI's own wording. The sources here don't give a founding year for FLI, so none appears here.

The 2023 Pause Letter and Its Signatures

The letter is titled "Pause Giant AI Experiments: An Open Letter" and is dated 22 March 2023. It went public in late March. The authors of the Stochastic Parrots paper, Timnit Gebru, Emily M. Bender and Angelina McMillan-Major, say March 28, 2023 was the public release date that most press coverage used.

What the Letter Asked For

The letter's central demand reads: "We call on all AI labs to immediately pause for at least 6 months the training of AI systems more powerful than GPT-4." It says the pause "should be public and verifiable, and include all key actors." If the pause cannot be enacted quickly, it says, "governments should step in and institute a moratorium."

The letter's policy list calls for:

• "new and capable regulatory authorities dedicated to AI"
• Oversight of powerful systems and the compute behind them
• Provenance and watermarking systems
• Auditing and certification
• Liability for harm caused by AI
• Public funding for AI safety research
• Institutions to handle economic and political disruption

The letter also asks labs and independent experts to use the pause to write shared safety protocols, audited by outside experts. It asks research to shift toward making existing state-of-the-art systems more accurate, safe and trustworthy.

How Many Signed and Who Checked

The Stochastic Parrots authors' statement, dated March 31, 2023, said the letter had "more than 2,000 signatories" at that point. Those signers included the Turing award winner Yoshua Bengio and Elon Musk. As of October 21, 2026, the letter page displays 31,810 signatures.

The Fake Signature Reports

Motherboard reported on March 29, 2023 that the letter carried false signatories impersonating OpenAI CEO Sam Altman, Chinese president Xi Jinping and Meta's chief AI scientist, Yann LeCun. The signature list was not verified at launch. FLI told Motherboard that all signatories were "independently verified through direct communication." That claim was made while the fake names were on the list.

After the impersonations surfaced, FLI removed them. It also paused the public display of new signatures while it verified each one. The sources don't give a final verified count or the number of fake names removed, so the only figures here are the three named impersonations. No confirmed statement from LeCun appears in the sources, so he is not quoted.

Max Tegmark's View on AI

Tegmark frames the danger as a question of who decides, not only what machines do. He told Motherboard the risk is that "we lose control to a bunch of unelected people in tech companies who get an outsized influence." The letter he backed through FLI asks for a verifiable pause, plus new regulatory authorities, audits and liability for AI-caused harm.

The sources here don't include a confirmed first-person quote about an AI "race" or "suicide race." Phrases like that circulate online, but none could be checked against a source, so none appears here. For the wider debate over AI risk, see our AI doomers explainer. For other groups pushing a pause, see our pause movement explainer.

The Criticism of Tegmark and FLI

The AI-Ethics Response to the Letter

Timnit Gebru, Emily M. Bender and Angelina McMillan-Major published a statement on March 31, 2023 rejecting the letter. They say it is marked by "fearmongering and AI hype" that focuses attention on hypothetical risks. They argue it "addresses none of the ongoing harms" from AI systems, including worker exploitation, data theft, synthetic media and concentration of power.

They name "a dangerous ideology called longtermism" as the problem and say FLI is generally aligned with that outlook. For the longtermism debate itself, see our longtermism explainer. They also say inflated talk about AI capability leads people to think a sentient being is behind the outputs. In their view, that puts accountability on the systems rather than the builders. They note that some recommendations match proposals already in their 2021 paper. They also say the letter relegates eugenics to a footnote as "potentially catastrophic."

Motherboard quoted more critics. Gebru called it ironic that the letter proposes pausing models more powerful than GPT-4 while ignoring concerns about GPT-4 itself. Bender said the letter was "dripping with #Aihype" and argued the real risks concern power concentration, oppression, and informational and environmental damage. Sasha Luccioni called the approach "essentially misdirection." Arvind Narayanan called questions raised in the letter "nonsense" and "ridiculous," and said the hype "makes it harder to tackle real, occurring AI harms."

The sources here don't include a direct FLI reply to these critics.

FLI Funding and the Nya Dagbladet Grant

Wikipedia records FLI's funding as a cryptocurrency donation of $665 million from Vitalik Buterin in 2021, $10 million from Elon Musk in 2015, and more funding from Jaan Tallinn. Buterin's donation came from Shiba Inu (SHIB) tokens he received from the Shiba Inu project in 2021. He split them between FLI and the CryptoRelief fund.

The donation's size is disputed. In a March 13, 2026 report, The Block said Buterin expected FLI could cash out only $10 million to $25 million at most, given SHIB's shallow liquidity. The same report says FLI "managed to liquidate roughly $500 million." The $665 million and $500 million figures may measure different things, such as token value at donation and cash actually realized. Neither was confirmed against a filing or an FLI statement in the sources. The sources also don't publish the exact number of tokens Buterin donated.

The Block reports that Buterin publicly distanced himself from FLI. He said the organization had undergone "an internal pivot" toward "cultural and political action as a primary method." He warned that "large-scale coordinated political action with big money pools is a thing that can easily lead to unintended outcomes." He called the approach "authoritarian and fragile," while also praising FLI's "pro-human AI declaration." The Block article has no FLI comment, and the sources here don't contain one either.

In January 2023, Tegmark was alleged to have signed a letter of intent for a $100,000 grant to Nya Dagbladet, a Swedish far-right outlet. Wikipedia says the grant was "ultimately rejected" and notes that his brother wrote for that outlet. Tegmark's account, as Wikipedia reports it, is that the Institute "ultimately decided to reject it because of what our subsequent due diligence uncovered." The sources don't say what role he played beyond signing the letter of intent.

FLI's statement, dated 18 January 2023, said it "finds groups or ideologies espousing antisemitism, white supremacy, or racism despicable and would never knowingly support any such group."

Critics of the Mathematical Universe Idea

Some critics dispute Tegmark's cosmology work, which is a separate debate from AI. Edward Frenkel, a mathematician rather than a physicist, calls the hypothesis "science fiction and mysticism." George F. R. Ellis calls an infinite ensemble of disconnected universes "completely untestable." Tegmark maintains the hypothesis is testable and predicts that physics will keep uncovering mathematical regularities.

Piet Hut and Mark Alford argue the idea conflicts with Gödel's first incompleteness theorem. Tegmark responds by restricting physical existence to fully decidable structures. He offers a narrower Computable Universe Hypothesis, which he admits faces "serious challenges." Jürgen Schmidhuber argues there is no way to give all infinitely many mathematical structures equal non-zero probability. Andreas Albrecht called the hypothesis "provocative" but said he "wouldn't dare" say he believed it.

Is Max Tegmark Legit?

His MIT professorship is on record, but his AI pause argument is contested and the letter he backed had documented signature problems.

The Case for Him

MIT lists him as Professor of Physics. His Ph.D. from the University of California, Berkeley was supervised by Joseph Silk, and his MIT research links physics and machine learning. Knopf published both of his books. FLI's own people page lists him as "Founder and Chair." The letter page showed 31,810 signatures as of October 21, 2026. After the impersonation reports, FLI removed the fake names.

The Case Against Him

FLI said all signatories were "independently verified through direct communication" while fake names were still on the list. Motherboard reported impersonations of Sam Altman, Xi Jinping and Yann LeCun. Wikipedia reports the allegation about the Nya Dagbladet letter of intent, which was ultimately rejected. Buterin distanced himself from FLI's pivot and called its approach "authoritarian and fragile."

Critics in the AI-ethics camp call the letter hype and misdirection, and they say it ignores harms AI already causes. Frenkel calls the mathematical universe idea "science fiction and mysticism." None of these points settles whether Tegmark's own judgment was sound, and the critics disagree with him on the substance.

What Remains Unsettled

The sources leave several questions open:

• How many of the 31,810 displayed signatures are verified, and how many fake names were removed.
• The true size of Buterin's donation, given the $665 million and roughly $500 million figures.
• FLI's response to Buterin's criticism, since no FLI comment appears in the sources.
• Whether Tegmark holds any equity, advisory role or other financial interest in an AI company. The sources don't say either way.
• FLI's current budget, headcount and donor list.

To judge the letter yourself, read its full text and the live signature count on FLI's letter page.

Sources

• MIT Department of Physics faculty page for Max Tegmark
• Wikipedia: Max Tegmark
• Future of Life Institute: Pause Giant AI Experiments, An Open Letter
• Future of Life Institute: Our People
• Stochastic Parrots authors' statement on the pause letter, March 31, 2023
• Motherboard: The Open Letter to Stop Dangerous AI Race Is a Huge Mess
• The Block: Vitalik Buterin questions FLI's political pivot, March 13, 2026
• Wikipedia: Mathematical universe hypothesis