6 ms·

Doesn't that imply our theories are "good enough" for all practical purposes? If they're impossible to empirically disprove?

• PlatoIsADisease 8mo ago
  If I have to make a guess, we are at the level of pre-copernicus in particle physics. We are finding local maximums(induction) but the establishment cannot handle deduction. Everything is an overly complex bandaid. At some point someone will find something elegant that can predict 70% as good, and at some point we will realize: 'Oh that's great, the sun is actually at the center of the solar system, Copernicious was slightly wrong thinking planets make circular rotations. We just needed to use ellipses!' But with particles.
  • davrosthedalek 8mo ago
    The sun is not at the center of the solar system. The intellectual leap was not to replace earth with the sun. Earth does not "revolve around the sun". The intellectual leap was to realize that the situation is somewhat symmetric -- they both attract each other, and they orbit around their center of gravity (which, yes, is in the sun. But not because the sun is the center.) This sounds like a distinction without consequence, but I think that's wrong. The sun is not special. It just has a lot of mass. If somebody learns: The earth orbits the sun-- They don't understand how two black holes can orbit each other. If somebody learns: The sun and the earth orbit their CM -- They will be able to understand that.
• doctoboggan 8mo ago
  The theories don't answer all the questions we can ask, namely questions about how gravity behaves at the quantum scale. (These questions pop up when exploring extremely dense regions of space - the very early universe and black holes).
• deleted 8mo ago
  [deleted]
• light_triad 8mo ago
  There's still huge gaps in our understanding: quantum gravity, dark matter, what happens before planck time, thermodynamics of life and many others. Part of the problem is that building bigger colliders, telescopes, and gravitational wave detectors requires huge resources and very powerful computers to store and crunch all the data. We're cutting research instead of funding it right now and sending our brightest researchers to Europe and China...
• idiotsecant 8mo ago
  Absolutely not. Newtonian physics was 'good enough' until we disproved it. Imagine where we would be if all we had was Newtonian physics.
  • nancyminusone 8mo ago
    You would still make it to the moon (so I've heard). Maybe you wouldn't have GPS systems?
  • mikkupikku 8mo ago
    Newtonian physics is good enough for almost everything that humans do. It's not good for predicting the shit we see in telescopes, and apparently it's not good for GPS, although honestly I think without general relativity, GPS would still get made but there'd be a fudge factor that people just shrug about. For just about anything else, Newton has us covered.
    • cozzyd 8mo ago
      quantum mechanics (also very much not Newtonian) is much more important to our day-to-day lives.
      • refulgentis 8mo ago
        Is it?
        • nerdsniper 8mo ago
          Flash memory (quantum tunneling), lasers (stimulated emission), transistors (band theory), MRI machines (nuclear spin), GPS (atomic transition), LED's (band gap), digital cameras (photoelectric effect), ...the list does, in fact, go on, and on, and on.
          • narcraft 8mo ago
            Did you intentionally list things that are clearly not essential to day-to-day life?
• Legend2440 8mo ago
  Typically whenever you look closely at an object with complex behavior, there is a system inside made of smaller, simpler objects interacting to produce the complexity. You'd expect that at the bottom, the smallest objects would be extremely simple and would follow some single physical law. But the smallest objects we know of still have pretty complex behavior! So there's probably another layer underneath that we don't know about yet, maybe more than one.
  • jhanschoo 8mo ago
    I agree, and I think that your claim is compatible with the comment that you are responding to. Indeed, perhaps it's turtles all the way down and there is systematic complexity upon systematic complexity governing our universe that humanity has been just too limited to experience. For a historical analogy, classical physics was and is sufficient for most practical purposes, and we didn't need relativity or quantum mechanics until we had instruments that could manipulate them, or that at least experienced them. While I guess that there were still macroscopic quantum phenomena, perhaps they could have just been treated as empirical material properties without a systematic universal theory accounting for them, when instruments would not have been precise enough to explore and exploit predictions of a systematic theory.
    • adrianN 8mo ago
      The experiments that lead to the invention of quantum theory are relatively simple and involve objects you can touch with your bare hands without damaging them. Some are done in high school, eg the photoelectric effect.
      • jhanschoo 8mo ago
        Whereas I did hedge my point regarding macroscopic quantum phenomena, I think that the quantum nature of the photoelectric effect would have been harder to discern without modern access to pure wavelength lighting. But you could still rely on precise optics to purify mixed light I suppose. But without even optics it should be even harder.
• csomar 8mo ago
  I think the problem is that GR and QFT are at odds with each other? (I am not quite versed in the subject and this is my high-level understanding of the “problem”)
  • ymolodtsov 8mo ago
    They require space to be two different things. And we kind of expect to be able to quantize gravity but none of the approaches that worked for three other interactions work here.
• hackingonempty 8mo ago
  Yes, for all practical purposes. This is the position of physicist Sean Carroll and probably others. We may not know what is happening in the middle of a black hole, or very close to the big bang, but here on Earth we do. "in the specific regime covering the particles and forces that make up human beings and their environments, we have good reason to think that all of the ingredients and their dynamics are understood to extremely high precision"[0] 0: https://philpapers.org/archive/CARCAT-33 https://philpapers.org/archive/CARCAT-33
  • throwaway81523 8mo ago
    ER=EPR says something completely shocking about the nature of the universe. If there is anything to it, we have almost no clue about how it works or what its consequences are. Sean Carroll's own favorite topics (emergent gravity, and the many worlds interpretation) are also things that we don't have any clue about. Yes there is stuff we can calculate to very high precision. Being able to calculate it, and understanding it, are not necessarily the same thing.
• recursivecaveat 8mo ago
  Maybe? We seem to be able to characterize all the stuff we have access to. That doesn't mean we couldn't say produce new and interesting materials with new knowledge. Before we knew about nuclear fission we didn't realize that we couldn't predict that anything would happen from a big chunk of uranium or the useful applications of that. New physics might be quite subtle or specific but still useful.
  • A_D_E_P_T 8mo ago
    All the stuff we have access to? There isn't even a general physical theory of window glass -- i.e. of how to resolve the Kauzmann paradox and define the nature of the glass transition. Glass is one of man's oldest materials, and yet it's still not understood. There's also, famously, no general theory for superconducting materials, so superconductors are found via alchemical trial-and-error processes. (Quite famously a couple of years ago, if you remember that circus.) Solid-state physics has a lot of big holes.
• sixo 8mo ago
  The point is not to make better predictions of the things we already know how to predict. The point is to determine what abstractions link the things we don't presently understand--because these abstraction tend to open many new doors in other directions. This has been the story of physics over and over: relativity, quantum theory, etc, not only answered the questions they were designed to answer but opened thousands of new doors in other directions.
• colechristensen 8mo ago
  Classical physics was indeed "good enough for all practical purposes" as well at the time... but those didn't include electronics, nuclear power, most all basic understanding of materials, chemistry, and just a tremendous amount of things. The point being it's not at all clear what we might be missing without these impractical little mysteries that so far are very distant from every day life.
• andreareina 8mo ago
  The fundamental theories are good enough in that we can't find a counterexample, but they're only useful up to a certain scale before the computational power needed is infeasible. We're still hoping to find higher-level emergent theories to describe larger systems. By analogy, in principle you could use Newton's laws of motion (1685) to predict what a gas in a room is going to do, or how fluid will flow in a pipe, but in practice it's intractable and we prefer to use the higher-level language of fluid mechanics: the ideal gas law, the navier-stokes equations, etc.
• adrian_b 8mo ago
  The existing theories are extremely far from being good enough for practical purposes. There exists a huge number of fundamental quantities that should be calculated from the parameters of the "standard model", but we cannot compute them, we can only measure them experimentally. For instance, the masses and magnetic moments of the proton, of the neutron and of all other hadrons, the masses and magnetic moments of the nuclei, the energy spectra of nuclei, of atoms, of ions, of molecules, and so on. The "standard model" can compute only things of negligible practical importance, like the statistical properties of the particle collisions that are performed at LHC. It cannot compute anything of value for practical engineering. All semiconductor devices, lasers and any other devices where quantum physics matters are not designed using any consistent theory of quantum physics, but they are designed using models based on a great number of empirical parameters determined by measurement, for which quantum physics is only an inspiration for how the model should look like and not a base from which the model can be derived rigorously.
  • jhrmnn 8mo ago
    This depends very much on what "practical purposes" are. For almost all conceivable technology, relativistic quantum mechanics for electrons and light, ie QED, is sufficient fundamental theory. This is unlike before quantum mechanics, when we basically didn't have fundamental laws for chemistry and solid-state physics.
    • adrian_b 8mo ago
      The vast majority of useful things cannot be computed with QED from fundamental principles. You cannot compute even simple atomic energy spectra. The fundamental laws of chemistry have not been changed much by quantum physics, they just became better understood and less mysterious. Quantum mechanics has explained various cases of unusual chemical bonds that appeared to contradict the simpler rules that were believed to be true before the development of quantum physics, but not much else has practical importance. Solid-state physics is a much better example, because little of it existed before quantum physics. Nevertheless, solid-state physics is also the most obvious example that the current quantum physics cannot be used to compute anything of practical value from first principles. All solid-state physics is based on experimentally-measured parameters, which cannot be computed. All mathematical models that are used in solid-state physics are based on guesses about how the solutions could behave, e.g. by introducing various fictitious averaged potentials in equations, like the Schroedinger equation, and they are not based on computations that use primary laws, without guesses that do not have any other justification, except that when the model is completed with the experimentally-measured values for its parameters, it can make reasonably accurate predictions. Using empirical mathematical models of semiconductor materials, e.g. for designing transistors, is perfectly fine and entire industries have been developed with such empirical models. However, the fact that one must develop custom empirical models for every kind of application, instead of being able to derive them from what are believed to be the universal laws of quantum physics, demonstrates that these are not good enough. We can live and progress very well with what we have, but if someone would discover a better theory or a mathematical strategy for obtaining solutions, that could be used to compute the parameters that we must now measure and which could be used to model everything that we need in a way for which there would be guarantees that the model is adequate, then that would be a great advance in physics.