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Expanding on your second paragraph, off the top of my head I can cite superconducting magnets and high temperature superconductors, both of which have benefitted from funding/interest related to large particle accelerators. Now you have companies building tokamaks with this technology.

Whilst they are not commonly used today, it is not entirely improbable that they play a significant role in the future.

There’s also some developments related to grid computing, sensors, and electronics, which could be reasonably useful in other contexts.

So yeah, chasing the next fancy particle itself is not very relevant to most people (though still very important in our quest of trying to understand the world around us), but it still contributes to technological progress.

Another aspect is international collaboration. It’s not perfect, but CERN and ITER are organisations within which Chinese, Russians, Americans and Europeans (and many, many others) work together towards a common goal.

Thank you for expanding on this -- I agree with all of these points. There is a real and tangible, albeit in this case indirect, value to have highly skilled people try to push that boundaries of what is possible technologically. It is easy to forget that the world-wide-web itself had its inception in at CERN -- an institution whose focus is particle physics.

In my opinion, another important reason to support of keeping these large accelerators alive is there is a very real chance that the expertise to build these kind of devices could atrophy or be lost entirely given the long timescales involved. Even if one is opposed to building this specific collider, I think the prospect of losing this kind of institutional knowledge is concerning (though if one finds these things useless, you might care less if we lost that capability).

Oh yes, good point about the Web. I know there’s a lot of cutting edge research on storage and computing distributed across the world to handle the sheer amount of data coming out of the LHC. It’s not implausible that this could help improve the Internet’s architecture.

I entirely agree with your second point. I’ll add that it is also important to keep these people (from highly specialised technicians and physicists to diplomats and support staff) employed in positions where they can keep their skills sharp. Some of them then go back to their countries of origin to apply this experience and knowledge to help improve research and policy at home, whilst retaining personal links with their counterparts abroad.

In the grand scheme of things, the expenditure is a rounding error anyway.

It was lost in the US after the supercollider project was cancelled in the 90s.

That's the same argument as weapon developers use, and weapon development contributed much more to fundamental physics than particle accelerators. The majority of funds after the WWII flowed to physics thanks to the nuclear arms race.

So what's your point? The weapon developers are correct of course. But the difference between weapons and super colliders is that super colliders are designer to help humanity instead of destroy it.

I can assure you weapon developers also think they benefit society. They usually say: WWIII did not happen only because of nuclear weapons. The question here is, what would benefit society more, spending said $21B on virology research or on a collider? Or maybe if you spend $21B on AI research, the computer will solve all the remaining theoretical problems of string theory in 0.21 s.

Of course weapons benefit society. I didn't say they didn't...

I agree with you that the current physics output from the high energy experiments are far removed from practical usages today, and that this has immense value in itself. However I feel that you downplay the value of the developed hardware and (especially) software required to perform these experiments.

As an analogy, I currently work on developing a medical imaging system where we track the trajectories of protons and heavy ions after they traverse a patient - in order to infer their energy loss and also the patient's "stopping power" map. With better knowledge of the stopping power we will be able to improve cancer radiation treatment with protons and heavy ions.

We would be nowhere without recent work in particle physics on large scale pixel sensors, Monte Carlo simulation software, readout systems, experimental cross sectional data (although not directly from the high energy experiments), particle tracking algorithms, electronics design for very thin sensors and radiation hard equipment ++.

You're probably right that my statement about "indirect" applications was a bit strong. I agree that there are numerous applications some fairly direct (like medical physics) and some very indirect (like the WWW) that have come out of work in particle physics.

But I think my main point, that applications of particle physics itself (and not the human and technological advances made to support it) are essentially non-existent stands.

You may be right, but it may be a distinction of low relevance.

The technological advances made to support particle physics may not have been possible without the effort to do the particle physics.

I.e. they are actually a result of the effort to understand the universe, even though they aren’t written down in the standard model.

It’s not at all obvious that we would have devised them any other way.

If that's the reason one wants to continue funding particle accelerators -- and it's a good argument -- then one needs to make precisely that argument (and not the argument made a few levels up by the original poster).

Sorry, you’ll have to disambiguate. Which argument should not be made?

Sorry, I didn't realize how nested this had gotten; this statement:

> One would argue that modern electronics are possible because research was done about Quantum Physics, a fundamental nature of reality.

which was making the connection that understanding frontier physics from 100 years ago directly enabled new technology, and that was a reason to support particle physics today (presumably b/c it might directly lead to similar advancements).

It’s not clear to me why we should make the distinction between what we write down in the model of physics, and what we write down in the engineering science books as a result of these endeavors.

What does it mean to distinguish these two?

I agree the distinction can get a little fuzzy at the edges, i.e. for technologies that, while not dependent on frontier physics, would only have been developed in the pursuit of (say) building a larger collider.

But I think there is a real difference in expectations between technology that operates on known physical principles and that which involves wholly new ones. Historically the latter has been associated with dramatic shifts in what is possible, for example our understanding of electromagnetism and quantum mechanics enables much of the modern world.

So I think presenting the study of particle physics in that light could mislead the public on just what is being done and what kind of outcomes it might precipitate.

Ok, but isn’t the premise of this line of reasoning flawed?

We didn’t know what our understanding of electromagnetism and quantum mechanics would enable in advance.

Suggesting that any science would lead to specific outcomes would be misleading, otherwise it wouldn’t be science - it would just be engineering. R&D.

Science is always just exploration, and the outcome in terms of tools is always incidental.

> Ok, but isn’t the premise of this line of reasoning flawed? We didn’t know what our understanding of electromagnetism and quantum mechanics would enable in advance.

No, but we did know what we had large gaps in our knowledge, even of things at close to human scales -- before those theories were discovered and worked out. It was then reasonable to expect that filling in those gaps might lead to new technology and applications also at human scales. And I'm not talking about direct applications, I'm talking about applications decades or more out -- but the fact that the energy scales were somewhat close to home meant such thing were possible.

From what we know about the current frontier in particle physics, nothing informs physics at human scales. This is a strong statement -- its many many orders of magnitude off in energy scale.

It could be that we're wrong about some that (and that's one of the reasons I think this research should continue) -- but it's not something that should be reasonably expected.

> Science is always just exploration, and the outcome in terms of tools is always incidental.

My comments were about how the science should be presented to the public in an honest way. And I think trying to sell people on science by quoting past developments that are quite different in character and expectations to what is being done today is dishonest and is a disservice to everyone involved.

The point that should be made is exactly the one you make above: science is about exploration -- full stop -- and we shouldn't make exaggerated claims about applications to sell people on it.

I think that’s fair, but it cuts both ways.

We shouldn’t make pessimistic statements about the potential benefits of the process of doing the research itself.

Science is valuable because of what we find, but it’s also always valuable because of what we learn to do in the process.

I agree we shouldn’t make exaggerated claims about benefits, but neither should we act as though one part is somehow incidental and not fundamental to why we do the exploration.

I believe there is. Observed universe shines on us in a broad spectrum of electromagnetic and gravitational waves and particles, so knowing it well and expecting what may come from it is important, because we utilize more and more of this spectrum. If you build a neutrino detector, you are looking at the whole universe and trying to separate your own signal from the background. In space some strange recurring radio signal may interfere with satellite communications, you may need to distinguish it from something else. It’s all practical right now, even if we are not yet building machines to exploit some new physical law.

Arguably the particle accelerator technology is useful for free-electron lasers, to the point where Globalfoundries wanted to base their next node shrink on an FEL-based lithography process.

I was surprised to see in recent years quite a lot of applications of neutrinos in imagery. E.g. in geology, to visualize the inside of monuments (e.g. pyramids) without opening them, etc.

Muon detectors are also application of particle physics. I will not be surprised if we’ll see more exotic particles being used, maybe in some areas of manufacturing, as a convenient carrier of certain energy. Particle colliders are the way to develop accessible technology for that purpose.

The hope is that a fundamental discovery will open the door to many other discoveries which could lead us to an understanding of ways to transfer energy between fields in new ways.p Making a Star Trek warp drive may be the only way for humanity to leave our galaxy.

True, but if we continue on our current trajectory (climate change, social inequality), we won’t make it to that future. While I understand, we have enough curious people to invest many long-term possibilities and theories, I do think we should focus more on current pressing concerns when we decide on such a costly project. I can’t help but think of the possibilities of building renewable energy, sanitization for the parts of the world that has been historically and systematically left behind.

Do you think it's likely that any of the post-60s particle physics will lead to new useful inventions? Any idea what they might be or where I could read about them?

I don't know of any promising prospects.

I think nuclear physics provides an instructive example that sits in between some of these extremes. Here the energy scales are way way lower than current frontier standards, but also fairly divorced from things in everyday life. Yet nuclear physics has applications (in medicine, in power and [unfortunately] in war). These applications do tend however to be quite specialized (we don't have atomic cars, vacuum cleaners or whatever) so it didn't revolutionize the world the way our understanding of electromagnetism or quantum mechanics did. [I don't want to downplay the effect of nuclear science, but it isn't ubiquitous in our lives].

Barring a fundamental change in our understanding, I would expect that trade off between energy scale and specialization to continue to hold and any developments based on particle physics (of the 60s-present) to be very specialized.

Let me be clear though -- you don't know what you don't know. It could be that what I think are reasonable expectations are wrong, and there are surprises waiting for us (this is one of the reasons I think particle physics is worth supporting).

In a sense though - that's what we should have been expecting all along. Particle physics may have had surprises for the experts along the way, but what it did not have are hidden ways to use those newly discovered particles without those huge energies; and similarly for the weakly-interacting stuff.

That may not hold forever; but it's not a crazy assumption. Something who's existence you cannot deduce without energies that need specialized billion dollar equipment to reach is almost by definition not ever going to create or influence ubiquitous tech. That's quite different from stuff like quantum mechanics; those effects are quite visible in fairly everyday situations (e.g. the double-slit experiment doesn't need anything too exotic, and obviously lots of modern tech relies on tricks classical physics might observe but not predict).

That means that if particle physics is to be relevant, it's most likely going to be in places that are not ubiquitous. Maybe it'll help astronomers understand the universe, and maybe that has some application down the line. Or maybe it'll be in absurdly expensive high-energy devices that matter even with only a few copies in the world (and let's hope those aren't yet more weapons).

Still, seems reasonable to be pessimistic about the usefulness of particle physics investments of this type.

Does quantum computing count as particle physics? It seems like this may be the future of computing.

It's speculation that it will ever be practical for computing, let alone in the near future. And even then I'm not sure how much that'll be related to recent experiments in high energy particle physics.

The experimental platforms that I am aware of that are been used to try and build quantum computers are based on condensed matter physics (superconducting junctions), atomic physics (trapped ions) or photons (quantum optics). None of this involves particle physics. The theoretical side of quantum computing, while a rich and deep field on its own, is an application of quantum mechanics and does not share any deep connection with particle physics.

Quantum computing will never be the future of computing. If we manage to make it work, it will at best be something like a TPU: a specialized processor for accelerating specific tasks. It will always be faster and easier to build more powerful classical computers than an equivalently fast quantum machine.

Eli5

Quantum computing only solves a few specific problems. Like showing every possible outcome. For instance print(x), and your goal is to get a through z.

But if the problem is linear, like 2+2, it doesn't help to have quantum computing.