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Liam Fedus

Liam Fedus

Computer scientist

Oct 8, 2026

2:58
Mm-hmm.
2:59
Uh, our data comes from our physical labs, and this is sort of our ultimate truth.
3:05
It's not enough just to do optimization against, um, some answers that were known in some papers or textbooks, because we're going beyond that, and I think that's one of the biggest differences.
3:15
But along with that, there's issues of, say, decision-making under uncertainty.
3:19
So when you're doing optimization against math, there's a, a high precision to it.
3:23
You're not really dealing with, you know, kinda like variance or uncertainties or, you know, aberrant measurements, whereas that's very key to, to our process.
3:31
Like, um, for example, when we are doing materials discovery loop, things don't come off the, out of the furnace labeled, right? Even the labeling process can be stochastic and noisy.

1 HR 11 MINS LATER

SwyxHOST
75:06
Yeah
15:56
And talk a little bit more about why you chose to start Periodic and what you guys are building.
16:01
Yeah.
16:01
One of the biggest objectives, I think, for this technology is to start changing the course and trajectory and speed of science.
16:09
AI for science is a really popular, uh, area now.
16:13
I think that's kinda the end game of this technology.
16:15
If we can start building up new knowledge, not just sort of, um, resurfacing and, um, recombining existing knowledge, but really like pushing the frontier, this would lead to just a huge acceleration and overall productivity, um, gives us agency to kinda begin to construct and do things in our physical world.
16:35
But I felt in order to do this, it was necessary to connect to the physical world.
20:25
Hmm.
20:18
What is your origin story?
20:20
Yeah, origin.
20:20
So I grew up in Maine and also had like a really early love for physics.
20:26
And so in college, I was actually a bit between physics, chemistry, economics, and I was part of a dark matter detection program.
20:34
And one of the key pieces for that was reconstructing the particle tracks, which became like a physics model.
20:41
But it's really a physics-informed machine learning model.
20:45
And so I started doing machine learning in physics in a very early stage.

21 MINS LATER

41:52
And on the LM side as well, which...
34:32
Mm.
34:32
Mid-training allows you to inject some of your, um, company's knowledge or know-how that may not be in the existing model.
34:39
And so basically, how do you internalize that? And this is something you can do in addition to just giving a search or rag.
34:46
It's basically the difference of an employee showing up and having to figure things out on the fly versus they've already kind of internalized some of the knowledge.
34:53
And then we do reinforcement learning.
34:56
So given those three pieces, we now have agents where we can start with a, a model.
35:02
Uh, it could be extremely bad on our benchmarks.
35:55
Uh, from your perspective, what are these AI systems really good at?
6:37
talk about how... you created ChatGPT.
6:40
So ChatGPT originally, the technology evolved very rapidly over the last few years.
6:48
When we were first creating it, it was a very standard RLHF pipeline.
6:51
So you have a pre-trained model, And it's sort of like this raw substrate.
6:55
And what you're trying to do is take this auto-completion model and turn it into something useful.
7:00
The way we did it at that point was we would have supervised data.
7:04
So given some input, we would say this is a desired output.

33 MINS LATER

39:57
What else?

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