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September 18, 2024·2 min read

Machine Learning at CERN: What's Actually Different

#CERN#Particle Physics#Life at CERN

Before joining CERN openlab, I assumed the main difference between industry ML and scientific ML would be the data — bigger, weirder, more specialized. That's true, but it's not the part that changed how I work day to day.

Being wrong has a different shape

In most applied ML, a wrong prediction is a bad experience for a user. In particle physics, a wrong prediction can look like a discovery. A model that's slightly miscalibrated in the wrong direction doesn't just hurt accuracy metrics — it can manufacture a signal that isn't there, or hide one that is. That changes the bar for what "good enough" means, and it changes how much of the job is calibration and validation rather than architecture design.

The detector is a co-author

Every model I build has to respect the physical constraints of the detector generating the data — its geometry, its resolution, its known blind spots. Ignoring that isn't a shortcut, it's a bug. Some of the most useful conversations I have in a week aren't with other ML engineers; they're with physicists explaining exactly what a particular sensor can and can't see.

Slower, on purpose

Release cycles here are intentionally slower than a typical product team's. A model doesn't ship until its behavior is understood, not just its accuracy. I've come to appreciate that pace — it's forced me to build better diagnostic tooling than I ever did when the incentive was just "ship it faster."

Why I'd choose this again

I came to CERN openlab for the technical challenge. I've stayed for the standard of rigor. It's made me a better engineer everywhere else the work touches, not just here.