Particle accelerators are pinging the deepest layers of reality that we can possibly reach. Deeper than anyone could have imagined just a few generations ago. That anyone can be cynical about that is hard to understand.
Technically, yes. But imagine our focus is Earth science. The name of the game is drill the deepest borehold. Now, the Kola Superdeep team could rightfully claim they are digging into the deepest layers of our terrestrial reality that humans, heretofore, have ever reached.
But if you only dig boreholes, you're not reaching our planet's iron core. At least not for, at the very least, centuries for materials science to catch up with science fiction. Instead, the secrets will be unveiled through seismology.
Similarly, it's fair to ask whether building bigger and bigger synchrotrons is akin to trying to discover the secrets of Earth's interior by drilling deeper and deeper boreholes. (Disclaimer: I have zero background in particle physics.)
I'd be happy to hear about other promising experiments we're ignoring, but unless there are very promising and expensive alternative experiments we're ignoring, there's no good reason not to keep pushing particle accelerators. Why stop following the best approach we have so far?
So, even if there is no alternative, there's no reason to spend the money. There is no rule of science or economics that if we spend 17bn euro on a new collider we'll get some new science. It's very much possible we'll get ~nothing, and thus the money is better spent on other research. If the astronomy community doesn't have a better use for it as you claim (I highly doubt that), then I'm sure some other important science does - maybe materials science, maybe in bio sciences etc. If particle physics has run its course with current technology levels, then we can put it on pause and invest in other more promising areas of physics.
1) you presume a collider only brings value if it can definitively prove/refute a theory, but the Wikipedia article lists a number of incremental improvements (ruling out "a very broad class of models for weakly interacting massive particles (WIMPs) in the GeV – tens of TeV mass scale" as explanations for dark matter, improvements "in precision measurements of Electroweak precision observables" which supports other research, as well as "new avenues in the study of the collective properties of quarks and gluons"). Can you prove these incremental improvements have a lower RoI than other experiments that we're currently ignoring?
2) the 17bn euro don't disappear into a black hole. The development of these experiments requires R&D in areas (e.g. cryogenics & magnetics) that have produced a lot of value, but are often expensive to advance. Pushing these fields means that a portion of the budget will follow your suggestion, but it will be focused on important topics. It's hard for me to gauge the RoI of your suggested approach because you haven't suggested such a focus - can you give some examples?
In conclusion: you're treating the RoI of accelerators as boolean, but it's not. There's a bunch of definitive incremental improvements as well as useful side effects, even when disregarding the potential for discovering unknown physics.
I am also one of the people whose money would be used to pay for this, so I have at least some entitlement to an opinion on the matter. Ultimately, they need to convince ordinary EU citizens like myself that it's worth investing in this.
Now, if I were in a position to write proposals that had even a small chance to attract 17bn euro of investments to a project I'd like to work on, I can assure you I could come up with dozens if not hundreds of small advantages the project could bring, without lying. Most of them would of course be bullshit and far from actually worth the money, but hey, that's the game. The reasons you quote from Wikipedia all strike me as an aspect of this: real things that the FCC could probably really do, but ultimately irrelevant.
For example, it could rule out a broad class of models of WIMPs as candidates for dark matter. Great. But does this actually mean anything for the advancement of science? Not really: there would still remain many other broad classes of models of WIMPs that are far beyond what could be proved with an accelerator. And there are many other at least as good theories of what dark matter could be that are also well outside this range. So, ruling out some models, ones that we anyway don't have any particular reason to believe are the best models, is in fact almost useless.
I know less about the others to understand whether they are as much bullshit or not. And even if they all are, this doesn't mean there is 0 RoI. But I also don't thing the RoI is as high as in other, less well studied areas of physics.
As for the engineering advances, the problem with that line of argument is always the same: if buidling the FCC has minor value, but will have positive side-effects of improving our ability to build X, then investing directly in X would be even better.
Your approval as a citizen sadly doesn't mean much - the EU is not a direct democracy, and I haven't come across data showing that this issue would influence elections in a meaningful way (please share any you should find!). The representative nature of our shared democracy can often be frustrating, but as a fellow citizen you'll have to convince me that it should turn into such an issue when I vote the next time, however the way you're assigning negative intentions without providing examples of better investments doesn't convince me that you're treating the subject in an objective way.
> And there are many other at least as good theories of what dark matter could be that are also well outside this range. So, ruling out some models, ones that we anyway don't have any particular reason to believe are the best models, is in fact almost useless.
Have you read studies that analyze existing theories regarding "discoverability" (for lack of a better term)? Or how did you arrive at "almost useless"? It's hard for me to know if the likelihood is closer to 0.0000000001% or 1%, and at least some analysis on this should be doable, even if just by counting the raw amount of possibly achievable/non-achievable theories.
> I know less about the others to understand whether they are as much bullshit or not. And even if they all are, this doesn't mean there is 0 RoI. But I also don't thing the RoI is as high as in other, less well studied areas of physics.
Okay, and what are those areas? What would the required investments be for what kind of RoI?
> As for the engineering advances, the problem with that line of argument is always the same: if buidling the FCC has minor value, but will have positive side-effects of improving our ability to build X, then investing directly in X would be even better.
Only if the expected RoI of the FCC is lower than the additional RoI of investing in X. I'm open to this being the case, but since both of us aren't physicists (and probably not knowledgeable in these kinds of budgetary questions), I need more than your word.
Particle accelerators are the very definition of diminishing returns currently.
I'm not saying that no such examples exist, but I need concrete examples. Possible new research for the FCC is pretty well defined, meeting similar requirements should be easy if there really are so many better places to invest the money.