Sabine Hossenfelder put the case against a new collider recently:
It is possible that in the data yet to come some new particle eventually shows up. But particle physicists are nervous. It’s not looking good – besides a few anomalies that are not statistically significant, there is no evidence for anything out of the normal. And if the LHC finds nothing new, there is no reason to think the next larger collider will. In which case, why build one? Sabine Hossenfelder, “How the LHC may spell the end of particle physics” at BackRe(Action)
Now here’s the case for it, addressing her concerns:
3) Particle theory is in a crisis. As my friend and colleague Gian Francesco Giudice likes to point out, crises are typically a productive moment. Since supersymmetry cannot be found by experiments, and the breathing space of its most natural instantiations is shrinking by the day, many theorists have turned to more complex ideas or to “effective theories” that describe new phenomena in a way that fits well with the measurements that experiments can produce. The point here is that at this juncture we cannot rely on theory to indicate the way. Should we then sit and wait for a new Weinberg to come along? It makes no sense. …
Concerning Sabine’s post
Sabine Hossenfelder, the star blogger and author of a bestselling book on the matter (“Lost in Math”, money very well spent if you ask me!), argues at her Backreaction site that the advocates of the FCC plan are overhyping the potential of their plan as well as the chances that it finds new physics. In a way, what she says is correct: the indicia that new physics be just around the corner are not strong at all…
Where I think Sabine is misguided (as has been pointed out by many commenters in her blog and in her Facebook thread) is, in my opinion too, that the absence of theoretical indications should never become a show-stopper to the investigation of Nature. To me, the fact that we can produce 40 TeV resonances if there exist any, is by itself a sufficient motivation to go out and try to do precisely that. Are there not enough anomalies in present-day data to indicate what we should look for in detail? Too bad, let us look for anything we can find, as Katie McAlpine explained well in her LHC rap. Tommaso Dorigo, “Why We Need A New Collider” at Science 2.0
So we should do it because we can, not because we really expect to learn very much? It may be that Dorigo is just not a good spokesperson for his position; he spends a good deal of time attacking Hossenfelder and her book.
Somehow, naturalism (nature is all there is) isn’t providing the hoped-for return on investments.
See also: Will the Large Hadron Collider doom particle physics? They’ll find the money to continue. Consider: The Standard Model begins with the hated Big Bang. Nothing that supports string theory, eternal cosmic inflation, or a multiverse has been found. Don’t many people just have to keep looking and keep quiet about what they find that wasn’t what they hoped for?
Sabine Hossenfelder: Particle Physics Now Belly Up. As It Happens, Her Book Is A Solid String Of 1’S At Amazon
and
Our universe understood at last: An expanding bubble in an extra dimension! The authors hope that their work will “pave the way for methods of testing string theory.” That could come in handy, you never know.
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