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In my field we call this "overfitting." String theory and multiverse work are adherent to all experimental evidence by design and offer no predictive capabilit
by iaw 10y ago
In my field we call this "overfitting." String theory and multiverse work are adherent to all experimental evidence by design and offer no predictive capabilities (correct me if I'm wrong, please).
You can design arbitrary systems to fit observations without identifying the underlying mechanisms, especially if said arbitrary systems are complex (which symmetry arguments are).
If these models are only predictive after the fact, then what good are they? The vindication for Einstein is that his various predictions are still being proven out a century later. Hawking found evidence that ran contrary to our theoretical understanding and has spent his life trying to explain the divergence.
String theories aren't in contention outside of the fringes, they're interesting mathematical models but they are on a par with our study of the ether in the late 19th century, something that will be looked back upon as a diversion away from the truth of our universe.
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- akvadrako 10y agoThis may be true of string theory but not unitary quantum mechanics, which predicts a multiverse. It makes quite specific predictions which are tightly constrained by experiments, for example the Born rule.
- iaw 10y agoI think you're making a leap when you say it "predicts a multiverse." (please correct me if you have field expertise) To refresh my memory I ran through this paper [1] briefly. My understanding is that multiverse arguments based on the Born rule are circular. One possible interpretation of the Born rule is the existence of a multiverse but it is not the only interpretation and it requires one to make some pretty big assumptions that the existing Quantum mechanics models being perfect representations of reality (which we know it is not). [1] http://www.math.ru.nl/~landsman/Born.pdf http://www.math.ru.nl/~landsman/Born.pdf
- akvadrako 10y agoOver the past year I've developed a good grasp on the modern consensus, by reading everything I can find that might shed light on the subject and lurking on physicsforums.com. Despite the common physicist trait of shying away from philosophy, there is a general acceptance that decoherence can lead to an effective collapse, which reproduces our classical world (and many others). Some arguments deriving the Born rule may be circular; I don't know - I don't see how that matters - because others are not. There are some critics but they mostly start from philosophical considerations: that a multiverse is untestable outside the quantum scale, imposes a high cognitive burden or requires us to redefine probability. Those objections are only valid if you consider a multiverse a priori unlikely; the evidence and math is clearly in it's favour. If you want better answers I would look through that forum, or consult a recent review of the literature around decoherence.
- iaw 10y agoReading up on decoherence, the phenomenon itself doesn't lead to a many worlds hypothesis but allows for the conjecture of many worlds. Information becoming immeasurable/irretrievable is not proof in and of itself of a multiverse. I have some modest undergraduate work in modern Physics, I think you may be taking the dominant voice on the physicsforums.com at face value when there's a high potential for self-selection bias in online forums. Going back to the experiment evidence and underlying mathematics there just hasn't been a breakthrough of any sorts.
- akvadrako 10y agoThe point is more that there is no need for a breakthrough, because there is no need to postulate a mechanism for actual collapse, since decoherence is sufficient to explain the results of experiments. I'm not sure what your argument is, but nobody is proving a multiverse, it's just an observation.