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> But when they tried to quantize gravity, they ran into unnatural infinities that had to be sidestepped with clumsy mathematical tricks. Maybe they run into u
by naasking 3y ago
> But when they tried to quantize gravity, they ran into unnatural infinities that had to be sidestepped with clumsy mathematical tricks.
Maybe they run into unnatural infinities because all of our formalisms in physics are still fundamentally continuous rather than discrete. Uncountable infinities are baked right into the foundations of how we use reason about these systems, so infinities will naturally result. Physics has repeatedly had to tame infinities by elaborate tricks, or by eliminating them entirely [1].
Some people are increasingly looking to discrete formalisms, and I think this is a promising way forward, both for mathematics and physics.
[1] Struggles with the Continuum, https://arxiv.org/abs/1609.01421 https://arxiv.org/abs/1609.01421
- qazpot 3y ago> Physics has repeatedly had to tame infinities by elaborate tricks, or by eliminating them entirely or In case of black holes by actually interpreting infinity as a real place in the universe.
- CuriouslyC 3y agoIf I were a betting man I'd say black holes have no singularity, but rather a core of extremely dense exotic matter (probably formed from top/bottom quarks) which we haven't detected because it decays quickly under less extreme circumstances.
- mr_toad 3y agoI think it’s true that once an event horizon forms no physical force (known or hypothetical) can stop a singularity forming. There may be some form of very dense matter that stops large stars from collapsing to the point where an event horizon forms in the first place, but that doesn’t seem to apply to super massive black holes. For super massive black holes the event horizon grows too fast.
- naasking 3y agoSingularities are a deficiency in GR, they don't really exist.
- GoblinSlayer 3y agoIt takes infinite time for event horizon to form, before that it's just dense. It's time dilation that stops formation.
- abdullahkhalids 3y agoI can't help but suggest "Information, physics, quantum: The search for links" [1] by the one and only John Wheeler. This philosophical paper is bold, bolder than most physicists ever would be. > Abstract: This report reviews what quantum physics and information theory have to tell us about the age-old question, How come existence? No escape is evident from four conclusions: (1) The world cannot be a giant machine, ruled by any preestablished continuum physical law. (2) There is no such thing at the microscopic level as space or time or spacetime continuum. (3) The familiar probability function or functional, and wave equation or functional wave equation, of standard quantum theory provide mere continuum idealizations and by reason of this circumstance conceal the information-theoretic source from which they derive. (4) No element in the description of physics shows itself as closer to primordial than the elementary quantum phenomenon, that is, the elementary device-intermediated act of posing a yes-no physical question and eliciting an answer or, in brief, the elementary act of observer-participancy. Otherwise stated, every physical quantity, every it, derives its ultimate significance from bits, binary yes-or-no indications, a conclusion which we epitomize in the phrase, it from bit. [1] https://philarchive.org/archive/WHEIPQ https://philarchive.org/archive/WHEIPQ
- CuriouslyC 3y agoDigital physics seems so obviously the correct approach from a philosophical perspective, it's a shame it blows up the math. Real numbers are the most ironically named thing ever, and infinity is a thought experiment - not a real thing. Any model of the universe based on such constructs should be heavily suspect outside the range of established observations, and taking predicted limit behavior seriously is just foolish.
- naasking 3y agoI think naive approaches to digital physics have been inadequate, but newer works have made good progress on important questions. Arguably one of the biggest tools in the physicists' toolbox are symmetries, and there's now a good account for those: A Noether Theorem for discrete Covariant Mechanics, https://arxiv.org/abs/1902.08997 https://arxiv.org/abs/1902.08997
- eigenket 3y agoSpeaking as a physicist I think its very far from obvious that digital physics (or anything else) is the correct approach from a philosophical perspective. Real numbers are so ubiquitous in physics because space-time (and other quantities) look really continuous.
- consilient 3y agoAgreed that digital physics is far from obvious, but the use of real numbers as our default model of the continuum is at least in part historical accident. We could have for instance easily ended up with locale-theoretic foundations instead, though I doubt the finitist crowd would find that any more satisfying.
- CuriouslyC 3y agoRational numbers can produce "continuous" values to a precision way beyond what any equipment you could get your hands on could differentiate without physically ludicrous postulates.
- 3y ago