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Comment by Bostonian | Hacker News Reader

I think in some areas of physics, such as high-energy physics, there is not much left to discover. The Standard Model works. What branches of physics are likely to see progress?

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I guess it's hard to say, because we don't know what we don't know. The famous example is Newtonian physics which seemed to perfectly explain everything.... until new tools and methods came out that were capable of showing it break down under extreme circumstances. That's how we ended up with Einsteinian physics, where it accounted for the old model and the new observed discrepancies.

So... how do we know that we will not find some bizarre scenario in the future the throws the Standard Model into a similar existential crisis?

I say keep your mind open.

Einstein's theory hasn't yet been reconciled with quantum theory. That's a good place to watch for progress.

I wonder if there is a Future Circular Collider that could help expand the standard model into this regime.

There unfortunately isn't, at least not at a scale that's feasible right now. [0]

[0]: http://backreaction.blogspot.com/2019/03/nonsense-arguments-...

That may require waiting to become a Kardashev III[1] civilization so we can do experiments where we know General Relativity and the Standard Model give different results. The energies required for the disagreements to show up are really insane.

[1]https://en.wikipedia.org/wiki/Kardashev_scale

More or less. We can hope that something more clever would be possible, like in the novel Schild's Ladder...

Though we'd have to hope that, unlike that novel, we don't accidentally set off a vacuum collapse. That would be unfortunate.

It will also be a civilization-scale experiment on quantum immortality, where we can't get negative result.

You'll excuse me for not wanting to test that.

Not really sure about that. Physicists are getting really frustrated by the fact that the LHC has found exactly the missing piece that the SM predicted (the Higgs) and zero evidence of any physics beyond that, anything that would get us closer to quantum gravity. No strings, no supersymmetry, not even any hints as to the nature of dark matter. All it has done is give new lower bounds to the energy scales at which something interesting might start to happen. For all we know, we might need a solar system size collider to attain the required energies.

>For all we know, we might need a solar system size collider to attain the required energies.

We just need to observe the collisions happening at these energies - we don't necessarily need to produce them ourselves.

Some physicists are starting to think about how we might be able to observe naturally occurring collisions at these energy levels rather than producing them ourselves.

IIRC that only buys you 2-3 orders over LHC energy.

Considering this would represent a continent-sized collider... I'll take it.

AIUI, the trick with colliders isn't so much creating high-energy collisions, but creating them exactly inside gigantic detectors that can measure what happens in those collisions, as well as the collisions having a known amount of energy and contents.

Well, to the best of my understanding, both are an issue with current colliders. I've not read any of the papers around the idea of observing collisions caused by high energy events elsewhere in the galaxy/universe, but the articles I read made it sound like this would solve a portion of the problem that we otherwise might not be able to without a solar system sized collider. They didn't make it sound like this would be anything we could do anytime soon, however. But potentially sooner than we'd be able to generate the energy needed to cause collisions at those energy levels.

I'm having trouble finding the articles I've read on the subject - I'll follow back up if I do manage to find 'em.

Although Einstein apparently knew about the Michelson-Morley experiment, it's unclear how much his development of relativity depended on it. He seems to have moved on to being motivated mainly by rationalist abstraction and the use of gedanken experiments, rather than actual experiments. The predictions of relativity were then confirmed by later observations and experiments.

"On the role of the Michelson-Morley experiment: Einstein in Chicago" http://philsci-archive.pitt.edu/4778/1/Einstein_Chicago_Web2...

It seems that the development of quantum mechanics has been much more driven by experimental results, although there are exceptions, such as Dirac's prediction of the positron.

There are lots of unexplained things that we already know about that are outside of the standard model. For example:

- The standard model doesn't explain any of the rest masses of the fundamental particles nor any of the coupling constants and a bunch of mixing angles. I think in total there are more than 30 input parameters that are completely unexplained

- Neutrino oscillation/masses are NOT part of the standard model as it predicts them to be massless

- Gravity is just not part of the standard model and currently cannot be combined properly with the other fundamental interactions

Someone please help correct my intuition here:

the harder it is to find flaws in the Standard Model, the harder it would be to use such new physics in engineering.

Basically I'm curious whether continuing failures to find new physics can be taken as evidence that, if and when we find the new physics, it will be very difficult to apply.

I'm not against science for its own sake, however. Just more of an engineer than a scientist, myself.

Don't forget that our engineering ability grows as well. I guess that when Einstein proposed his relativity theories, it seemed totally inapplicable. But fast forward a few decades, and we got GPS which wouldn't work without them.

Much more impressive are the gravitational wave detectors.

I remember that when they discovered electrons they thought that it’s also totally useless.

"the harder it is to find flaws in the Standard Model, the harder it would be to use such new physics in engineering."

I think that is very likely, but not necessarily guaranteed. I use similar logic with regard to FTL and time travel; if physics has not quite entirely ruled it out, the window is getting smaller and smaller, and is already to the point it's entirely plausible that even if it's theoretically possible there may be no conceivable engineering path to get to it, even for a hypothetical civilization that can fling black holes around.

However, we can't entirely rule out the possibility that some new physics will come along that will reveal how to easily "flip" matter into anti-matter (there seems to be no fundamental reason why this is impossible, it's just... too hard to be useful), or enable the creation of some state of matter or energy that may be exceedingly unlikely to be created naturally [1], but once created could be leveraged into something useful, or other such things. Stabilized muon fusion [2]? Relatively & QM fusion will certainly reveal something new about gravity; it can't be entirely ruled out that it will in some way be useful to engineering. (Although in this particular case, remember we can eliminate not just the "scientific" theories, but also observe engineers have yet to blunder into anything that seems to indicate any manipulation of gravity in any sensible way. Every real-world device ever built is also a test that shows that particular device must not be doing large-scale gravity manipulation.) Will quantum computers reveal some limit of reality's ability to calculate, and will that limit somehow itself turn out to be useful? Maybe.

Still, I tend to think that as much fun as flights of fancy about time travel, FTL, or bizarre alien tech can be, that the most likely hypothesis by far is that we are indeed very unlikely to discover anything in particle physics anymore that will be of any engineering value.

But I wouldn't counsel disappointment. There's still a lot of room at the bottom. We're not going to run out of technology in our lifetimes. If particle physics bores you, check out what's going on in materials science. They're making qubits sing and dance on command. It may still not build UFOs, but they're doing weird stuff in there.

[1]: As a sort of example, see: https://en.wikipedia.org/wiki/Strangelet#Dangers (Stranger Danger has nothing on Stranglet Danger.)

[2]: https://en.wikipedia.org/wiki/Muon-catalyzed_fusion

If applying the new physics requires gigantic particle accelerators, sure.

But maybe it's under a completely different rock, that we haven't thought of turning over.

The nice thing about precision nuclear physics is that often lower energies are enough -- most accelerators actually have too much energy to measure the proton radius for example. And energy recovering linacs for these energies can be build quite small. Think Basketball court.

Depends on the kind of difficulty. If it's quantitative, as in requiring orders of magnitude more energy, mass or time, then yes.

But it might be just more difficult qualitatively, like some different and non-intuitive way of interpreting everything, which might only require switching a few equations and changing some procedures.

If the effects require an accelerator the size of a small country to show up, then it's unlikely they'll be useful in anything small.

I think people have been misled by science fiction. Stories posit all sorts of interesting and exciting physics not because that's plausible, but because it makes interesting stories.

The Standard Model works with two significant asterisks. It is almost certainly not mathematically consistent, due to the presence of Landau poles in the hypercharge and in the Higgs self-coupling. It also does not include gravity. Neither of these caveats is a problem at experimentally accessible energies, but they do indicate that there's something left to discover. It's a bit irritating: We know we're missing something. We just don't know what.

Gravity, dark energy, dark matter. There is still a lot to discover.

The standard model lacks gravity.

I would like to believe this is a double entendre.

There's still physics in every successive new digit of the physical constants. The gravitational constant is only known to roughly 5 digits. Get to work!

While it is never safe to affirm that the future of Physical Science has no marvels in store even more astonishing than those of the past, it seems probable that most of the grand underlying principles have been firmly established and that further advances are to be sought chiefly in the rigorous application of these principles to all the phenomena which come under our notice. It is here that the science of measurement shows its importance — where quantitative work is more to be desired than qualitative work. An eminent physicist remarked that the future truths of physical science are to be looked for in the sixth place of decimals.

Albert A. Michelson, 1894, just 11 years before Einstein first published about special relativity.

One thing that's always interested me is that the recent history of breakthroughs doesn't tell you when the next one will arrive. For instance reconciling quantum mechanics and gravity, we don't know if we're within 11 years, 110 years, or even 1100 years!

It seems people like newton or Einstein come around every few hundred years. So another huge leap may take a while.

Seems like a good reason to make sure everyone is given the opportunity to achieve their fullest potential. The more we keep ourselves as a species oppressed by one another, the less likely we are to experience the Newtons and Einsteins condemned to rice fields and coal mines.

It may be unlikely to see progress in a subfield even if there are major unsolved problems. Particle physics is one of those branches.

But see https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_p...

It would be neat if we had a better model for superconduction.

The standard model still doesn’t explain gravity, dark matter, or dark energy. There are still ways to go.

Complex systems and emergent behavior in these.

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