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That's arguably what String Theory is good for, producing interesting, entertaining, and possibly even useful math. What it seems to fail at is making realistic

• ekjhgkejhgk 10mo ago
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  • bsaul 10mo ago
    as i know really nothing about the subject, could someone explain why parent was downvoted ? is it for the tone, or the content ? Because, i , having viewed the youtubers in question, had the same opinion about string theory.
    • shin_lao 10mo ago
      Because String Theory hasn't delivered falsifiable predictions, yet keeps expanding to accommodate failure.
      • ekjhgkejhgk 10mo ago
        What do you mean by "falsifiable"? Do you mean that have been falsified? Of course, no standing theory delivers falsified predictions, when that happens you throw the theory in the garbage. Do you mean that can be falsified in principle? In that case String Theory has falsifiable predictions, I gave you one. In principle, we can make experiment that would falsify special relativity. In fact, we've made such experiments in the past and those experiments have never seen special relativity being violated. The test of special relativity are the most precise tests existing in science.
        • drdeca 10mo ago
          I suspect what they mean is that there is no outcome of an experiment such that, prior to the experiment, people computed that string theory says that the experiment should have such a result, but our other theories in best standing would say something else would happen, and then upon doing the experiment, it was found that things happened the way string theory said (as far as measurements can tell).
          • ekjhgkejhgk 10mo ago
            But there are such experiments. String theory says that the result of such experiment is: Lorentz invariance not violated. > but our other theories This is not how scientific research is done. The way you do it is you a theory, the theory makes predictions, you make experiments, and the predictions fail, you reject that theory. The fact that you might have other theories saying other things doens't matter for that theory. So string theories said "Lorentz invariance not violated", we've made the experiments, and the prediction wasn't wrong, so you don't reject the theory. The logic is not unlike that of p-testing. You don't prove a theory correct is the experiments agree with it. Instead you prove it false if the experiments disagree with it.
            • ogogmad 10mo ago
              > But there are such experiments. String theory says that the result of such experiment is: Lorentz invariance not violated. This is not a new prediction... String theory makes no new predictions, I hear. I don't understand why you need to be told this. To your point, there exist various reformulations of physics theories, like Lagrangian mechanics and Hamiltonian mechanics, which are both reformulations of Newtonian mechanics. But these don't make new predictions. They're just better for calculating or understanding certain things. That's quite different from proposing special relativity for the first time, or thermodynamics for the first time, which do make novel predictions compared to Newton.
              • ekjhgkejhgk 10mo ago
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      • drdeca 10mo ago
        It has delivered falsifiable postdictions though. Like, there are some measurable quantities which string theory says must be in a particular (though rather wide) finite range, and indeed the measured value is in that range. The value was measured to much greater precision than that range before it was shown that string theory implies the value being in that range though. Uh, iirc . I don’t remember what value specifically. Some ratio of masses or something? Idr. And I certainly don’t know the calculation.
      • sesm 10mo ago
        The word 'falsifiable' comes from Popper's criterion, which is central to scientific methodology. What it means: if theory predicts something, and later observations show that prediction doesn't hold, then the theory is incorrect. String theory doesn't work this way, whatever was measured will be explained as an afterthought by free parameter tuning.
    • ekjhgkejhgk 10mo ago
      Because a lot of people felt this applied to them (this was the intention) and were hurt. Good on you for being able to articulate it. Respect.
  • jameshart 10mo ago
    Forgive my non specialist questions here, but doesn’t special relativity predict that special relativity is preserved at all scales?
    • ekjhgkejhgk 10mo ago
      No. Special relativity postulates that special relativity is preserved at all scales. It's an axiom. Comes from nowhere. It's assumed. This is what a theory is: assume XYZ is true, and see how much of the world you can explain. Why is XYZ? That theory doesn't explain it. Theoretical physics is: what is the smallest set of XYZ assumptions that can explain other theories. So if you can come up with a theory that's internally self-consistent that _predicts_ something which is postulated by another successful theory, that's a very convincing result.
      • drdeca 10mo ago
        Pardon, but, huh? I very much thought that Lorentz invariance was built into the assumptions of string theory. Concluding from “A AND B” that “A”, while it does reach a conclusion that is distinct from the assumption, is not impressive. If string theory does not bake SR into its assumptions, wouldn’t that make the way it is formulated, not manifestly Lorentz invariant? Don’t physicists typically prefer that their theories be, not just Lorentz invariant, but ideally formulated in a way that is manifestly Lorentz invariant? Of course, not that it is a critical requirement, but it is very much something I thought string theory satisfied. Why wouldn’t it be? Like, just don’t combine coordinates in ways that aren’t automatically compatible with Lorentz invariance, right? If you formulate a theory in a way that is manifestly Lorentz invariant, claiming to have derived Lorentz invariance from it, seems to me a bit like saying you derived “A” from “A AND B”. If string theory isn’t manifestly Lorentz invariant, then, I have to ask: why not??
        • ekjhgkejhgk 10mo ago
          Lorentz invariance is built into some descriptions of some stringy theories. For example chapter 1 of the Polchinski, you have the 26-dimensional bosonic string which is constructed to be Lorentz invariance. Obviously in this case it's not a "prediction", but then again, it's just a toy-model. Our Universe doesn't have 26 dimensions and doesn't have only bosons.
  • munchler 10mo ago
    That’s just piggybacking on a prediction of special relativity itself. If string theory predicted something novel that’s testable, that would be a lot more noteworthy.
    • ekjhgkejhgk 10mo ago
      > That’s just piggybacking on a prediction of special relativity itself. Let me stop you right now to inform you you don't understand how scientific theories are structured. Special relativity is not a prediction of special relativity. Likewise, 1+1=2 isn't a predict of arithmetic, it's the starting point.
      • munchler 10mo ago
        If you are suggesting that string theory is somehow more fundamental or powerful than special relativity, and so SR is a mere consequence of ST, that’s a claim that probably requires more explanation or evidence.
        • ekjhgkejhgk 10mo ago
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  • noone_important 10mo ago
    I am not sure what you are refering to. You absolutely can break Lorentz Invariance in string theory[1]. There is a reason why even some string theory researchers call it the theory of anything. [1] https://inspirehep.net/literature/262241 https://inspirehep.net/literature/262241
    • ekjhgkejhgk 10mo ago
      Wellllll. Despite the title, the paper does not make a claim about string theory. The starting point is the "Witten string field theory" which is a field theory engineered to have properties like string theory. Nothing guarantees that theory is exactly like string theory. In addition, the idea is perturbative in nature, there's no guarantee that perturbative effects are in fact realized in the full quantum theory - exoteric cancellations happen often in field theories with many symmetries. This is two degrees of questionable. So A) the paper isn't actually about string theory and B) it's not clear that the claim it makes is actually correct for the field theory it supposedly applies to.
      • noone_important 10mo ago
        Well this is just an early example of the lorentz breaking string theory niche. You can find a lot more. In the short time frame where opera had this supposedly faster than light neutrinos, a lot of papers were published in that regard. For example you can have string theories that lead to finsler spacetimes, which were used to explain the opera results.
        • ekjhgkejhgk 10mo ago
          I literally have no idea what our conversation has to do with opera results, or what you think that shows, but just lost all interest in continuing this conversation.
          • wizzwizz4 10mo ago
            People are not likely to look for unphysical models, if they're trying to do physics. The connection is social.
• jfengel 10mo ago
  No Theory of Everything is going to make realistically testable predictions. That's a problem of the domain, not the theory. The unification energy between the graviton and quantum field theory is on the order of 10^19 GeV, over a dozen orders of magnitude beyond anything we can generate. We might get lucky that some ToE would generate low-energy predictions different from GR and QFT, but there's no reason to think that it must. It's not like there's some great low-energy predictions that we're just ignoring. The difficulty of a beyond-Standard-Model theory is inherent to the domain of the question, and that's going to plague any alternative to String Theory just as much.
  • munchler 10mo ago
    I think that’s highly debatable. For example, dark matter particles with testable properties could be a prediction of a ToE. Or the ToE could resolve the quantum measurement problem (collapse of the wave function) in a testable way.
    • yablak 10mo ago
      What's the "quantum measurement problem"? And why is it a problem? I get the wave function collapses when you measure bit. But which part of this do you want to resolve in a testable way?
      • munchler 10mo ago
        It’s the question of how the wave function collapses during a measurement. What exactly constitutes a “measurement”? Does the collapse happen instantaneously? Is it a real physical phenomenon or a mathematical trick?
        • yablak 10mo ago
          I thought that what constitutes a measurement is well understood; it's just the entanglement between the experiment and the observer, and the process is called decoherence - and the collapse itself is a probabilistic process as a result. AFAIK an EoT is not required to design experiments to determine if it's a real physical phenomenon vs. a mathematical trick; people are trying to think up those experiments now (at least for hidden variable models of QM).