DP Dwarkesh Patel Dwarkesh Patel Hosts the Dwarkesh Podcast, a long-form interview show on AI progress, timelines, and the people building frontier models, along with economists and historians.

“If I think about how the brain works versus what you're describing here, the differences might be that while you can do structured sparsity in these accelerators, in the brain there's unstructured sparsity — any neuron can connect to any other neuron, not in ways where they'd be column aligned. Then there's the fact that memory and compute are co-located. Maybe that actually isn't a big difference. The other difference is that the clock cycle in the brain is much slower than on computers, partly to preserve energy.”

Dwarkesh Podcast · AI Research & Frontier Labs · May 2026

“If I think about how the brain works versus what you're describing here, the differences might be that while you can do structured sparsity in these accelerators, in the brain there's unstructured sparsity — any neuron can connect to any other neuron, not in ways where they'd be column aligned. Then there's the fact that memory and compute are co-located. Maybe that actually isn't a big difference. The other difference is that the clock cycle in the brain is much slower than on computers, partly to preserve energy.” — Dwarkesh Patel, Dwarkesh Podcast

Offered near the end of a blackboard lecture on chip design, as Dwarkesh works out which brain-versus-silicon differences are actually fundamental and which are artifacts of how we build things. He talks himself out of one of his own three candidates mid-list. Pope's reply is that the co-location point is exactly right.

Dwarkesh Podcast · 2026-05-22 Listen to the episode → More from Dwarkesh Patel → More AI Research & Frontier Labs quotes →

Transcript

Dwarkesh Podcast Around 1:12:22 into the episode
Dwarkesh Patel

branch predictor to like execute both branches at once or what does it do?

Reiner Pope

So the issue is that when I've got a series of instructions like instructions, instructions, instructions, instructions, if I have a branch like here, if this instruction is branch, the actual processing step of processing an instruction takes a really long amount of time. It takes maybe five nanoseconds or something like that. So like the time to actually notice that I've got a branch and then like evaluate the Boolean, whether it's true, and then update the program counter to the new target and then read from the instruction memory for that. That could take actually five nanoseconds to finish. And so in reality, this may finish somewhere down here. I don't want to, but like I want to run a clock speed that is much faster than what five nanoseconds allows. Five nanoseconds is 200 megahertz clock speed. I would like to run at one or two gigahertz or something like that. And so I need to run other instructions while the branch is being evaluated. And so I really just want to keep running the following instructions that happen after me. But that might have been wrong. If the branch ended up being taken, then I need to know that instead of evaluating these instructions, I actually need to jump to wherever the target is and run these instructions instead. And so the purpose of the branch predictor is genuinely to predict based on before you even get to this instruction to be like five cycles earlier to predict there was going to be a branch that's going to happen.

Dwarkesh Patel

So if I think about how the brain works versus what you're describing here, at a high level, the differences might be that while you can do structured sparsity in these accelerators and then save yourself some area that you would have otherwise had to dedicate to these gates, in the brain, there's unstructured sparsity. Any neuron can connect to any other neuron and not in ways where they'd be column aligned or whatever. Then there's a fact that memory and computer are co-located. I guess you could say in a way the memory and computer are co-located on

Reiner Pope

this is exactly the co-location in some sense of the memory. That's right. That's right.

Dwarkesh Patel

Yeah. Yeah, so maybe that actually isn't a big difference. And the other, maybe a big difference is that the clock cycle on the brain is much slower than on computers. And partly that's to preserve energy because the faster the clock cycle, the bigger the voltage needs to be in order to identify for the signal to settle and to identify what state of transistor is at. That's right.

Reiner Pope

That's right.

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