CERN releases report on the feasibility of a possible Future Circular Collider

[0] https://backreaction.blogspot.com/2025/04/why-cerns-new-coll...

It's not true at all.

I'll come back and write some up over the next 20 minutes.

There hasn't been a significant new particle discovery, but none was expected other than Higgs, as far back as 2006 when I was still screwing around in graduate physics.

I honestly can't remember the last time a new particle was randomly discovered by experiment that wasn't already proposed and agreed to as sound-in-theory. It's much cheaper and faster to do theory, then built what you need to verify, than to crank up energy as high as you can and hope for the best (I'd hazard a guess this ran out of steam by the 50s/60s at the latest)

The shell games are:

1. claiming it is a proton collider[^1 source] designed to look for new particles [^2 comment].

2. false equivalence between China putting in their latest 5 year plan to make a plan to make something that will transition to being a proton collider. And it's worse than that:

If they immediately started after the plan was complete and on schedule, they'd be done in 2048 and transition from e/p to protons in 2066.

CERNs plan is to be done with e/p in 2042 and transition to protons in 2070. That's 4 years later, but it's comically irrelevant. That's not getting done sooner, that's just transitioning to doing stuff we already can do faster, the cool thing and why both are interested in building one is the electron/positron collider stuff, not scaled up proton collider stuff.

Content: - The project would transition to a proton collider at the end of its lifespan as a novel tool, in 2070.

- It is proposed to operate by 2042, assuming funds dispersed over 12 years, starting in 2030.

- It will operate as a electron-positron collider for the intervening ~3 decades before transitioning to essentially LHC with 4x power.

- Electron / positron is a unique collision form, chosen to allow for more precise measurement, such as the LHC discoveries of discrepancies in the Standard Model.

- This is very important work. The more precise you nail down these uncertainties, the more theorists can do to verify their work, allowing the experimentalists to know where to look for new stuff, if any.

[^1 source] Via Sabine link: "CERN wants to build a new particle collider which will smash protons together at roughly 6 times the energies seen at the Large Hadron Collider."

[^2 comment] This is the undercurrent of the whole criticism, I cannot explicitly source it to one sentence. It's also bizarre: I can't remember the last time experimentalists got to discover something without the theorists telling them where to look. It's cheaper that way! LHC was a failure too by that standard. There simply aren't any candidates in the theory that are accessible at humanities near-term energy levels, the Standard Model's worked beautifully, modulo these tantalizing discoveries at LHC of small discrepancies that electron/positron collisions let you explore.