[gglon]

> Isn’t it nice (...) advance our understanding of the fundamental forces of nature?

The criticism is that the ROI = (the potential advance) / (invested money) is too small. As you pointed out it can be argued that the real goal is elsewhere: in the engineering / technology or science of complex systems. Creating a big machine that verifiably works brings many unexpected advances in many fields. And what is more important it is a symbol of human advancement which unites people and inspires them to pursue science. Since humans need a clear goal to invest much resources in a constructive endeavor. It may not be that important though that the ROI in fundamental physics is small, as long as people work hard together. But it can be argued that the whole process begins to resemble religion more than a scientific method; which can be problematic as religions have a bad reputation among scientific community.

[orbifold]

An organisation like CERN is extremely hard to replicate and easily destroyed and dragged down by a thousand cuts. The EU is funding similar moonshots in Neuroscience , Graphene, Quantum Computing and most recently machine learning. They all provide case studies what can go wrong in such a big science project (in fighting, diverging goals, huge administrative overhead, bureaucracy, political grand-standing).

The people working at CERN directly and their collaborators truly belief in the goal of understanding the fundamental forces of nature. And they had tremendous success doing so. They are the gold standard for a well managed long running big science project. Just recently they found the Higgs boson. Hossfelder worked for years on extremely speculative ideas in quantum gravity, they weren’t super well received, most people liked string theory better. Bottom up and top down reasoning in particle physics phenomenology suggests there are more discoveries to be made at the energy frontier. I like to see a future where eventually we build a solar system sized particle accelerator not stop at a radius of ~100 km

[Joker_vD]

> ROI = (the potential advance) / (invested money) is too small

That's unknown in advance. To take example from maths, the conic sections, braid theory, number theory—they all used to be very abstract and un-applicable parts maths, until one day.

[TheOtherHobbes]

If it's unknown in advance surely it's more rational to spread the research out instead of putting most of the available eggs in a single basket.

CERN found Higgs - which was proposed decades before CERN was built. There is nothing like the Higgs proposal around today.

That's the real problem. Spend $20bn on some new models, and then you can spend $20bn chasing the most interesting prospects.

That's far more likely to get you somewhere exciting than the experimental equivalent of throwing more spaghetti at the wall and hoping some of it does something unexpected.

[SiempreViernes]

> Spend $20bn on some new models, and then you can spend $20bn chasing the most interesting prospects.

This is a very incorrect description of the problem. The situation in basic particle physics is that models are super plentiful; Six months in 2016 saw 500 different papers written to explain a novel signal that ended up not being real, so it's not models that are missing.

[thiagotomei]

"CERN found Higgs - which was proposed decades before CERN was built." ---> This is factually incorrect.

   * CERN: founded 1954, as a lab for nuclear physics

   * PRL electroweak symmetry breaking papers: 1964

[tsimionescu]

Professor Hossenfelder and others have written long books about why the probability of finding new physics based on not liking the aesthetics of the current maths (naturalness, supersimetry, grand unification) is extremely likely to fail, and has been constantly failing for ~50 years.

If our way of generating new theories has given bad predictions for 50 years, at what time should we stop and try out other ways of extending the confirmed theories?

It is unknown in advance if putting your hand through a fire will hurt you this time as well, but after 50 years of doing so, perhaps it's time to stop.

[SiempreViernes]

They make qualitative arguments, nobody has any realistic prediction of what the probabilities are.

And the problem has never been making new theories, the problem is always that we have a very good model, and no principled way for choosing between all the possible theories that gives rise to almost precisely that model.

So people tried to invent reasons and so far nobody has had any luck. And Hossenfelder is correct that in hindsight naturalness wasn't a very good rule.

But by the same hindsight, no theory that could be detected in previous experiments would have worked either. In this view, making the experiments at all was a complete waste, we should just have drawn the winning theory from a hat and stopped all further work.

[tsimionescu]

The point is that there are known problems in the foundations of physics (the measurement problem, the reconciliation of general relativity and quantum mechanics to name the 2 best known ones) and that they should be by far the biggest focus for new research - not GUTs and solutions for un-naturalness.

If we have a theory that could solve the measurement problem (or detect quantum gravity etc.), and a plausible experiment for that theory, we should perform this experiment - it may well yield valuable data whatever result we get.

Conversely, if we have a theory that predicts that more particles may exist at higher levels of energy and nothing else, then there is no good reason to perform this experiment. Especially if the precise level of energy is a free parameter of the theory, so the theory won't change if the experiment fails.

> And Hossenfelder is correct that in hindsight naturalness wasn't a very good rule.

I believe that she is correct that naturalness wasn't a very good rule at all, not just in hindsight. It's as good a rule as it would have been to expect all numbers to be multiples of Pi.

[SiempreViernes]

To claim that the standard model has nothing to do with the quantization of gravity is very strange, part of the motivation for a GUT is that it would be a huge help towards making a theory of everything. And a TOE is precisely a unified treatment of the standard model forces and gravity.

The measurement problem isn't a physics thing, just like naturalness that's more of a life-style choice. In fact, the only reason to have problems with wave-function collapse is precisely a naturalness reasoning, technically it makes very accurate predictions just fine.

[tsimionescu]

> part of the motivation for a GUT is that it would be a huge help towards making a theory of everything. And a TOE is precisely a unified treatment of the standard model forces and gravity.

A GUT is specifically the part of a TOE that has nothing to do with gravity... A TOE is a GUT + a theory of quantum gravity.

If we had the Standard Model + a theory of quantum gravity, this could be a complete theory of the universe (pending explanations for dark matter, dark energy etc.). These could very well be completely separate phenomena, there is no reason to believe they reduce to a single phenomenon - that there exists a TOE.

> The measurement problem isn't a physics thing, just like naturalness that's more of a life-style choice. In fact, the only reason to have problems with wave-function collapse is precisely a naturalness reasoning, technically it makes very accurate predictions just fine.

This isn't entirely accurate. There is a very clear quantitative question behind the measurement problem: what kind of system constitutes a measurement device, in the sense of invoking the need for the Born rule? There must be some precise size/kind of system that, when a particle interacts with it, you can no longer use Schrodinger's equation to predict its movement after that interaction - you must apply the Born rule. We know that this doesn't happen after a particle collision, but that it does happen after a collision with a "detector".

This is a clear empirical question (you don't need to call it a problem), well within the realm of physics. It may be extremely difficult to answer, but I see no reason to imagine it is a priori impossible to resolve.