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Home » Transcript: Jeff Dean Interview on The 1% Rule for Building in AI with Diana Hu

Transcript: Jeff Dean Interview on The 1% Rule for Building in AI with Diana Hu

EDITOR’S NOTES: Jeff Dean — Google’s Chief Scientist and the engineer behind MapReduce, Bigtable, TensorFlow, the TPU, and Gemini — sat down with Y Combinator’s Diana Hu for a wide-ranging conversation on where AI is headed next. They cover everything from the future of low-latency inference hardware and “context engineering” to Dean’s famous napkin-math instincts, the origin stories of the TPU and MapReduce, and his advice for founders trying to find defensible problems in an era of increasingly capable general models. Along the way, Dean reflects on rejection, taste, and what he’d do if he were starting his career today. READ THE FULL TRANSCRIPT BELOW:

Introduction

DIANA HU: All right, should we get started, Jeff?

JEFF DEAN: Sure, sounds great.

DIANA HU: Jeff, welcome, and thank you so much for being here — especially since I just got a cold. Thank you for being here.

JEFF DEAN: I’m afraid I’ve lost my voice. I don’t normally sound quite like this, but we’ll do what we can.

Revisiting the Junior Engineer Prediction

DIANA HU: So, you built MapReduce, Bigtable, TensorFlow, the TPU, Gemini. We could spend a whole hour on all these things you’ve done, but what I love is that you’re still making bold predictions in public.

Last year, in May 2025 at AI Ascent, you said that AI is at the level of a junior engineer. That was about a year ago. How close are we to that prediction?

JEFF DEAN: I feel like the models have been getting a lot better at agent-based, longer-running coding tasks, and it seems pretty clear that they are now actually pretty capable. Depending on exactly your definition of junior engineer, it seems pretty spot on, I would say.

DIANA HU: What did you underestimate from that prediction?

JEFF DEAN: I think the ability to do more and more complex tasks has been growing faster than I thought. And I also think outside of coding, these agent-based systems are really starting to shine in other domains. That’s going to be an important trend in the future.

DIANA HU: So give us another bold prediction. What do you think is going to be the 2027 edition?

JEFF DEAN: I think you will see a lot more automation of ML systems themselves — basically getting ML systems to improve their capabilities by running lots of experiments, breaking things down into subproblems, running those subproblems in a tight automatic experimentation loop, putting the results together, and being able to get some improved system out from that fully automated problem decomposition and automated experimentation.

I think that’s going to be really exciting. That also applies not just to ML, but to other fields of science and engineering. Basically anything where you can have a measurable objective, I think you can make a lot of progress these days.

The “It Fits in Memory” Moment for 2026

DIANA HU: Now let’s go back a little in history. Back in 2001, Google Search used to run on hard drives. You and Sanjay did the math and realized that at some point the whole search index would finally fit in all of the RAM of all the computers you had running. You made that radical realization, and in a few days with Sanjay you shipped in production a whole new search version that worked in RAM rather than on hard drive. That was the thing that got Google searches to be so fast.

History tends to remix. What is the “it fits in memory” moment right now in 2026 that everyone in this room should be thinking about and designing for?

JEFF DEAN: It’s a little different, but I think you’re going to see more and more high-performance, low-energy inference hardware systems, because everyone is now realizing that inference is the key to making these agent-based systems available to more and more people, and that latency is really important.

Specialization of the hardware is a key way you can make things more energy efficient and lower latency than more general-purpose computational devices like GPUs or TPUs.

DIANA HU: Because I think everyone here is used to waiting for responses on models.

JEFF DEAN: Waiting is no fun.

DIANA HU: Master of speed. So you’re saying, what if we don’t have to wait anymore?

JEFF DEAN: I think — imagine what you could do with something where the latency is 50x better.

DIANA HU: Interesting thought. Now, what’s one assumption that perhaps 6,000 people in this room hold as already false about AI?

JEFF DEAN: That’s a good question. I think probably one thing is people don’t quite realize how possible it is to have agent-based systems that can run not just for an hour or two on a problem you care about, but for some problem domains, and with highly capable models underlying them, you can get them to run for days or weeks and do really complicated tasks.

Some people are starting to see inklings of this, but I don’t think everyone has really internalized it, and that’s going to be a pretty big deal.

DIANA HU: What’s a particular task that you have run that has run for weeks? What did you tell the agents to solve?

JEFF DEAN: You can tell agents to go off and implement completely new versions of software in different programming languages that might have better safety properties or better performance properties, and then they can go off and actually do that in a pretty serious way.

Napkin Math and the Origin of the TPU

DIANA HU: That’s pretty cool. Now, one thing you’ve been very well known for is that you’re really good at napkin math. One of the stories about you is that back in 2013, when speech recognition started to work at Google, you did the napkin math where if every Google user used their phone and talked to it — used the speech recognition system for just three minutes a day — you found that the system would require doubling the server fleet, which would be really expensive just to do speech translation.

JEFF DEAN: Yeah.

DIANA HU: And instead you basically built a custom chip.