PhD Candidate @berkeley_ai; prev Student Researcher @google

San Francisco, CA
Joined February 2026
The year is 1897, horseless carriages are denied permission to be on roads by Washington D.C. The year is 2026, people are trying to deny driverless carriages on the roads of Washington D.C.
DC is facing a jobs crisis. Rushing the legalization of autonomous vehicles is irresponsible given the anticipated AI-related job displacement and disruptions that put countless workers at risk.
5
42
9
173
21,147
Justin Kang retweeted
Super proud of the work we’ve done at @hiddenweights with @rox_ai to fine-tune an outbound reward model, achieving high accuracy at a fraction of the cost. Great collaboration!
Coding agents got good by writing code, getting feedback, and improving thousands of times. Agents doing commercial work never got that loop, until today. With @hiddenweights, we trained an Outbound Reward Model on real cold emails + the edits sellers make to AI drafts before they hit send. The reward model: - Is 5x faster and up to 30x cheaper than an LLM judge - Picks the seller-edited draft 80% of the time - Gets 1.75x the avg reply rate on top-scored emails 🧵 on how we did it:
2
15
775
This is a great post. But the fact that "It’s acceptable to write papers in theory conferences that assert an algorithm exists without ever writing it down." isn't inherently a bad thing (Shannon). "achievalbility proofs" are useful if we have a reasonable model of the world.
OpenAI’s faster Fourier transform is less a mathematical breakthrough and more a malicious exploit of mathematical traditions. argmin.net/p/faster-fourier-…
2
101
Basically completely agree with @minilek.
Mike was my colleague at Berkeley, and he's been fairly skeptical of deep learning's trajectory for years. Most scientists are skeptics, and it can take a big shock to get someone to consider a possibility that goes against the anchoring effect coded in our DNA. I too was somewhat of a skeptic until ~6 months ago, and people ask me all the time why I joined Anthropic. It started in April, when a friend I've known for 20 yrs messaged me saying he'd be in the Bay Area in a week, and he suggested we meet up. I invited him to my house for dinner, and he told me he had just joined Anthropic. He said the models were becoming increasingly more capable, and he believed both that they'd soon be smarter than him and also that all intellectual work would be highly devalued in the near future, and lastly that society was not at all ready for what's coming. I'd of course heard claims similar to this before, but not from a friend I'd known for this long, and who I trusted, at my dining room table. It was the initial shock needed to destabilize my own anchoring. Also, I've been fortunate to work with and/or mentor many smart people in my life (e.g. Fields medalists, a 4x Putnam Fellow, IOI first place winners, etc.), so I feel pretty calibrated in recognizing very smart people, and this was someone who is definitely very smart and with impressive such credentials. So, it was hard to ignore this friend saying the models would be smarter than even him in particular. After that dinner, I decided to do an informal survey, calling and meeting up with a lot of my friends who now work on improving model capabilities at these frontier labs. They all agreed with that first friend. These were all people I'd known 10, 15, 20 years, who mentored me, or I mentored them, or we met professionally in academia. These are people I trust, and their beliefs on this topic were consistent. I then spent a whole lot of time understanding the missions of different companies, and talking to current and former employees and people in leadership. I read Dario's (long) essays and watched videos on YouTube of company leaders being interviewed. Anthropic's stated mission "to ensure that the world safely makes the transition through transformative AI" felt like exactly the right guiding principle to handle such a society-disrupting technology, and everyone I spoke to at the company was very aligned with this mission. It's easily the most mission-focused place I've ever been at, and everyone takes the work extremely seriously and with a profound sense of responsibility. And now here I am. And being on the inside, the pace of progress has surprised me more than I first imagined. The moment that pure mathematicians are in, to me, is just a microcosm of what I predict a much larger of society will be grappling with in the not too distant future, and I really hope our leaders and the general public internalize sooner than later just how significant a moment we're in.
1
1
122
Amazing!
We’re releasing a broad range of new mathematical results produced by an internal frontier model. We’ve been consulting with the independent Advisory Group on Mathematics and Artificial Intelligence at the Institute for Advanced Study, and we have drawn on their advice and public recommendations to inform how we release these results. github.com/openai/math
1
84
Justin Kang retweeted
Actually 3 of 6 were already resolved.
mathematicians and muse spark collaborated to solve 6 open problems in math: 1. The Strict Threshold for Gaussian Ellipsoid Fitting 2. Finite-Time Blow-Up of Radial Negative-Energy Solutions for the Mass-Critical Biharmonic Nonlinear Schrödinger Equation 3. Semiabelian Groups Need Not Be Monomial 4. Tightness of the Cycle-Based Relaxation for Completed Length-Three Alpha-Cycles 5. String Two-Point Function = Height Function on a Curve 6. On Solvable Evolution Algebras and a Conjecture by García-Martínez and Pérez-Rodríguez
3
9
2
128
15,227
Justin Kang retweeted
Fix the headline: Muse spark can find solutions of already solved problems. But so can Google
mathematicians and muse spark collaborated to solve 6 open problems in math: 1. The Strict Threshold for Gaussian Ellipsoid Fitting 2. Finite-Time Blow-Up of Radial Negative-Energy Solutions for the Mass-Critical Biharmonic Nonlinear Schrödinger Equation 3. Semiabelian Groups Need Not Be Monomial 4. Tightness of the Cycle-Based Relaxation for Completed Length-Three Alpha-Cycles 5. String Two-Point Function = Height Function on a Curve 6. On Solvable Evolution Algebras and a Conjecture by García-Martínez and Pérez-Rodríguez
5
10
1
170
13,607
Replying to @petergostev
but language models in 2026 really are very different from language models in 2021. reasoning traces and various forms of RL beyond RLHF are a substantially different training procedure. they model different things. the training objective is vastly different.
4
1
30
2,275
Justin Kang retweeted
The world of R&D is forking into two paths: the token-abundant research, and the token-starved research. The future is in the former - evidentially, the progress by today's top AI industry teams and neolabs is breathtaking, where researchers’ human brilliance is super charged by AI’s assistance. Every research university president should be reading this report and reflecting on what the future of higher education research should be. openai.com/index/research-ac…
1
1
28
11,851
Great post!
evals ≫ harness optimization (fast learning) ≫ model post-training (slow learning) Most agentic tasks don't need slow learning loops at all. Even when the goal is post-training, you'd first need high SNR evals, then optimize the harness on the signal to get the performance up, and then "distill"* the resulting system behavior back into the weights. * Yes, I called it distill.
3
179
Cool work by Dewi and co.
How much reasoning can GPT-6 Astra do without CoT? @AISecurityInst puts its no-CoT time horizon at ~30mins on math. We run the Think Fast benchmark to measure this on a wider range of tasks. Our *rough estimate* is that Astra’s 50% TH is in [8mins, 1 hour].
1
152
Justin Kang retweeted
The next era of AI will be won across the full stack. OpenAI’s Jalapeño results are another strong signal. Training, inference and agents place very different demands on compute. There is no single architecture that is best for every workload. The future is heterogeneous computing, with hardware and software co-designed to deliver the most useful intelligence per dollar. The inference era is here! openai.com/index/the-full-st…
11
34
2
272
81,871
Yes very excited about this direction!
Training for counterfactual simulatability may help maintain monitorability. Earlier this year @Justinkangs @dswg97 @noahysiegel and I introduced a new simulatability evaluation to work towards this goal. Getting the metric design right (and hence incentivising the right behaviour in training) is hard. We discuss some of these challenges in our paper, and I'll be sharing more thoughts on things we missed soon. Our metric isn't perfect, and I'd be excited to see more work explore this space. arxiv.org/abs/2602.02639
1
47
Justin Kang retweeted
Training for counterfactual simulatability may help maintain monitorability. Earlier this year @Justinkangs @dswg97 @noahysiegel and I introduced a new simulatability evaluation to work towards this goal. Getting the metric design right (and hence incentivising the right behaviour in training) is hard. We discuss some of these challenges in our paper, and I'll be sharing more thoughts on things we missed soon. Our metric isn't perfect, and I'd be excited to see more work explore this space. arxiv.org/abs/2602.02639
Bullish on this direction. Having a metric for explanation quality makes it possible to hillclimb, and counterfactual simulatability seems right. Adam et al. created a dataset+pipeline that creates more diverse+realistic test cases than prior work & do interesting exps on it. Can also train models to write better post-hoc explanations of their behavior, as highlighted in this thread.
3
1
30
2,059
Justin Kang retweeted
The natural next step following Neel's argument: why not build models that are more monitorable by design? The interp community needs to take model building more seriously in the current safety landscape, as opposed to doing just "reverse engineering"
Who looks at the agents that attacked HuggingFace and thinks "I need to make it easier for them to communicate efficiently, in ways that are hard to monitor"? It is a boon to safety that models reason and talk in natural language. Work like this makes the world a worse place
2
12
1,147
Justin Kang retweeted
Excited to share that I've joined @turingcom as CTO. After two decades in AI research, I can't wait to push the frontier here; working with the top AI labs and partnering with enterprises to put it to work. Onward. 🚀
Turing welcomes Ece Kamar (@ecekamar) as Chief Technology Officer. Ece joins to lead Turing's technology and research strategy, helping steer the company through our next phase of growth as we scale across both frontier AI labs and Fortune 500 enterprises. We’re advancing the AI frontier by providing the human expert data, RL environments, evals, and benchmarks that define what agents can do, and also translating that research into reliable, adaptable agentic systems enterprises can depend on, with sovereignty built in from the start. We’re doubling down on software engineering, enterprise knowledge work, and frontier STEM. Ece comes from Microsoft, where she led the AI Frontiers Lab as Corporate Vice President, driving research from foundation models to agentic AI and building the tools, benchmarks, and open-source projects used across the field, including the Phi models and AutoGen. She co-authored the "Sparks of AGI" research paper and holds a PhD from Harvard. Welcome to the team, Ece. We’re excited for what’s ahead!
36
11
336
23,479
Justin Kang retweeted
I'm excited to co-found this new AI safety nonprofit research institute in Cambridge, MA, with an amazing team. Join us in making AI safe by design. resi.org
The Institute for Responsible Superintelligence (RESI): a nonprofit founded by Shafi Goldwasser, Adam Kalai, Vinod Vaikuntanathan. @ShafiGoldwasser @Vinod_MIT @AdamFungi resi.org Our goal: build scientific foundations needed to make superintelligence safe by design
30
51
8
588
81,181
A friend shared this snippet from a Claude Code session. Sure to get the old heart rate up! Stay safe out there, everyone!
7
11
5
164
30,579
Justin Kang retweeted
“Theory is the first term in the Taylor series of practice.” — Thomas M. Cover
1
6
4
68
12,855
Interesting post!
Having reviewed the OpenAI Black Hat talk, I now suspect that CoT monitoring would have provided only low-precision, redundant signals of the attack on Hugging Face. I extended my post with this argument: web.stanford.edu/~cgpotts/bl…
59