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Physics is caught at a strange point in its evolution: At the moment it is deeply dissatisfying that our theories describe the universe that is accessible to o
by niemandhier 3y ago
Physics is caught at a strange point in its evolution:
At the moment it is deeply dissatisfying that our theories describe the universe that is accessible to our experiments so well.
- PartiallyTyped 3y agoEven worse is that some of our predictive theories about the nature of the universe can not be tested. Unlike string-theory that has no predictive power, these theories make predictions on such extreme scales that are just impossible - with our current knowledge and tech - to verify, such as exotic forms of matter like strange matter [1]. [1] https://en.wikipedia.org/wiki/Strange_matter https://en.wikipedia.org/wiki/Strange_matter
- pmoriarty 3y agoWhat technical advances do we need in order to test them?
- Filligree 3y agoA Kardashev 2 to 3 civilization. Unless we're missing something big, the way to test it will involve light-year-sized particle accelerators.
- brabel 3y agoI am not sure about that. Observing astronomical events like black hole collisions, for example, which perhaps amplify quantum mechanics effects to phenomena we may be able to observe one day, even from light-years away... may be one way around this... Or creative ways of using large masses, like planets and even stars, to make measurements of tiny things - similar to how Earth-size telescopes can be approximated by much smaller ones, spread over a large area.
- PartiallyTyped 3y agoSpeaking of, some recent papers who that we can use pulsars to make galaxy scale gravitational measurements. By obseeving changes in pulse frequency and we can track whether a gravitational wave is going through it!
- nonameiguess 3y agoElectroweak theory was confirmed when we had large enough particle accelerators. I remember reading at some point that grand-unified theories that combine electroweak with strong force can be tested by a sufficiently high-energy accelerator, but the estimated size of such an accelerators would be around the orbit of Pluto.
- PartiallyTyped 3y agoIf we could bend gravity enough in the “opposite” direction (eg “negative energy” if such a thing even exists), and we could somehow manipulate magnetic fields enough to get all close and personal to neutron stars without getting sphaghettified and somehow could sample their inner core and see whether they are made of strange matter.. well we’d have an answer. But this for example is so freakishly absurd that it seems impossible even for scifi. A type 3 civ, if it exists, could potentially do that; but it’s one thing to extract energy off stars, type 2 and 3 and another thing to manipulate the inner core of neutron stars.
- Byamarro 3y agoThe question is also whether it's meaningful to polish our deeply mathematical models to scales so extreme that we may have troubles in reaching them. Keep in mind that this is just some model of reality, not necessarily how reality truly works. A true paradigm shift that would have implications in our scales would be much more meaningful.
- phkahler 3y ago>> At the moment it is deeply dissatisfying that our theories describe the universe that is accessible to our experiments so well. That should be very satisfying.
- darkwater 3y agoThe dissatisfying part comes probably from the fact that our technology will be limited to more or less what we already have, if there are no experimental breakthroughs that prove theories as inadequate.
- marcosdumay 3y agoYeah, that would be the case if the theories taken together made sense, and if the Universe wasn't full of unexplained things that should fit what we observe at the experiments.
- deleted 3y ago[deleted]
- sidlls 3y agoIt's satisfying to (continue to) verify existing theory. If we perform an experiment which may shed light on the gaps and flaws in our current models and it simply confirms them, it's unsatisfying. We know our current models in physics are incomplete. But we are struggling mightily to bridge models in different domains (relativity/quantum mechanics) and to fill in gaps within domains (as here, in quantum mechanics). And if we can't make progress, i.e., if our experiments aren't helping us fix the gaps, it's disappointing.
- phkahler 3y agoI think the gaps in theory need to be addressed first. A theory that correctly bridges the gap should also shed light on why the situation today is this way. What if QM and relativity are both correct in the context we view them? What if higher energy isn't what's needed to reconcile them? Einstein "simply" took the observation that the speed of light is constant in all reference frames, and relativity followed from that. Granted, he had to throw out the idea that time is constant. So what assumption might we take for granted that needs to be thrown out? Or more specifically what is the core set of things that conflict between QM and relativity? I'm asking for something far more specific that "QM and relativity can't both be right". It's in details that are probably way beyond my understanding.
- alexfromapex 3y agoThe strangest part of modern physics to me is how inaccessible the concepts are. The terminology and ontology are extremely complex and it seems no one has a grasp of the fundamentals like what actually is a photon and what medium is present in a vacuum that allows things like gravity to propagate?
- tines 3y agoThe medium for gravity is spacetime, as gravity is not a force but instead just a deformation of spacetime. A photon is an excitation of the EM field.
- RajT88 3y agoThis was what I was taught in high school.
- svachalek 3y agoThis is the definition in relativity. They haven't been able to make that idea work in quantum physics, despite it explaining practically everything else, so one theory or the other needs an adjustment.
- contravariant 3y agoMy hot take is that they haven't quite been able to make it work for quantum physics either, they just got lucky that their makeshift solution works provided things don't couple together too tightly. Also quantum field theory seems be just plain bad at explaining classical phenomena, which dominate general relativity. To me at least it seems quite difficult to describe a basic electromagnetic from the QFT, other than pointing at the Lagrangian in the path integral and saying something about how contributions outside its extremum will cancel out. Though perhaps I'm simply missing some trick here.
- tux3 3y ago>what actually is a photon It depends what answer you're looking for! We can tell you how photons behave, how to recognize them, and how to predict what they do. For hard philosophy questions, that's more under sections 100-119 of the Dewey Decimal than something physics aims to answer >what medium is present in a vacuum that allows things like gravity to propagate That's a little like asking who is in charge of pushing the sun around the Earth. There's a presupposition in that question, you should first ask why you expect there to be a medium, besides nondescript vacuum
- sesm 3y agoIt feels dissatisfying because most of those theories are overfitting of models with tons of free parameters to all available experimental data, and when new experimental data appears a new free parameter is introduced to the model. The actually useful theories, that reduce the number of free parameters are yet to be discovered.
- nologic01 3y agoNot the case. We are talking physical theory not LLM's. It is only in cosmology where there is arguably quite a bit of parametric freedom.
- PartiallyTyped 3y agoAdding, physical theories are predictive. The theory is constructed first and is more constrained than what it aims to predict. It’s not machine learning where you learn a model from data, we build the model and then verify its predictions. We is used colloquially. I am not a physicist. I am a mathematician working as an SDE.
- spacebanana7 3y agoParameter estimation on its own isn't real science. Hypothesis should be statements about reality, like that a given material is a superconductor. With enough lawyering, one can argue that statements around whether model #53sa7r describes a phenomenon accurately qualify as hypothesis. But the success or failure of such hypothesis rarely make for interesting papers to anyone but statisticians. And they don't often contribute to the human ability to reason about reality, build new things or predict the future. Like econometric models that never forecast with accuracy >10 years in advance.
- Nifty3929 3y agoThis exactly. Or at least it seems this way to me, as a non expert with some knowledge. Add another particle, or term, or whatever to make it match. Feels very inelegant. I like your description of overfit, which hadn’t occurred to me before, ironically though I spend a lot of time with ML. When teaching ML I talk about adding loops to the Ptolemaic planets-orbit-the-Earth-model - and how it actually worked pretty well because they spent a lot of time adding loops to the orbits to make it fit. It was overfit.
- nologic01 3y agoIs that really the case though? If we rank phenomena along the energy scale the accuracy of the description starts fraying at the low energy ends. Tangible ambiguities and loose ends are mostly evident in cosmology,eg in the form of this or that "dark stuff" but it is conceivable there are other very subtle phenomena hidding in plain sight (e.g., accessible with desktop experiments)
- IKantRead 3y agoIt feels a bit like contemporary physics has caught up to the concerns of 18/19th century philosophers. Descartes, Leibniz, Hume, Kant and others, while disagreeing with each other in major ways, all agree on one big concern: We're fundamentally limited in our knowledge about "things in themselves" outside of our consciousness and the perceptions we receive. Naively we think "oh, looks there's a flower!" but for these philosophers a big question was: how much can we really know about the actual thing that is the flower, beyond the (potentially suspect) information that our mind receives through the senses and our mental models (include the concept of 'flower'). In a very practical way I think we might be bumping into these limits. Which isn't surprising since what was driving these questions for those philosophers was concerns about the foundations of the then rapidly emerging scientific fields.
- civilized 3y agoI am not sure philosophers have so much identified limits to our knowledge, as perhaps "thing in itself" is a vague and contentless concept that we struggle to let go of.
- mjburgess 3y agoThat isn't naive at all. Oh look, there really is a flower. The set of sceptical propositions, say S, which make this "naive" are far more naive than the truth of there being a flower. That era of philosophy had yet to learn that philosophical propositions are themselves subject to scepticism, and when balanced against the ordinary, are far far more doubtful. What falls away, as naive, under scepticism is scepticism itself.
- indigochill 3y agoI probably fall in the middle. We can only make statements about what's more or less probable by getting insight into what exists beyond our perception, but by definition we can't perceive what's beyond our perception so we have no data to determine which is more or less likely. Either position is one of faith, not logic. For that matter, trusting that logic is sound is itself a position of faith. Hofstadter in GEB refers to positions like these as "axioms": statements that are impossible to formally prove within a particular system but from which we can derive statements that follow from those axioms through rules (the most fundamental of which are themselves axioms, like the statement in geometry that two points make a line) governing symbolic manipulation within a particular system. I like the concept and find it useful for wrangling logic and philosophy although I also note that it is itself subject to accepting certain axioms.