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New theory seeks to unite Einstein's gravity with quantum mechanics
- atombender 3y agoPrevious: https://news.ycombinator.com/item?id=38526877 https://news.ycombinator.com/item?id=38526877
- dang 3y agoThanks! Macroexpanded: New theory claims to unite Einstein's gravity with quantum mechanics - https://news.ycombinator.com/item?id=38526877 https://news.ycombinator.com/item?id=38526877 - Dec 2023 (196 comments)
- AnimalMuppet 3y agoIt's testable! And maybe not just theoretically testable, but realistically testable. So they're not just pontificating, nor even pontificating in a mathematically consistent way. TL;DR: They're assuming that spacetime is not quantized, but is as GR describes it. This produces a consistent theory that predicts that measured mass will fluctuate very slightly.
- wegfawefgawefg 3y agoPersonally I think the universe is a cellular automaton rule. Particles dont exist they are just percieved gliders in rule following substrate. A wave in the ocean doesnt exist any more than any other part of the water that isnt in the wave. We just focus on the wave because our brains are good at seeing moving shapes for hunting. The substrate graph is updated by travelling rule applicators which dont require energy. Theyre like the updating edge of stacking faults between planes in crystalography. Gravity slowing down light is just due to the travel speed of rule applicators being fixed. Higher graph density but fixed node updates per time means it takes longer to update a given volume.
- j4yav 3y agoAnd here's Tom with the weather.
- nradov 3y agoSo how would we test that hypothesis?
- optimalsolver 3y agoAsk the string theorists.
- wegfawefgawefg 3y agoIm agnostic until we have very tiny microscopes. Until then we are stuck at a funky high level abstraction. The table of quarks and particles we have is like what would happen if we were trying to figure out what our computers were made of by interacting with a url bar, and coming to the conclusion that the fundamental components of a computer are like... a table of HTTP response status codes. Not to say that its useless, just that its not zoomed in enough.
- inputdev 3y agoWhat do you mean by "travelling rule applicators"? Also by "travel speed of rule applicators being fixed"? Is there a fundamental space and time in which the rule applicators exist?
- wegfawefgawefg 3y agoYou wouldnt need an explicit time. The rule applicator just traverses the graph and updates a node based on adjacent nodes. Time for us is just the difference in relative sequence lengths between updates applied to volumes at our scale.
- qubex 3y agoWolfram, is that you?
- DylanBohlender 3y ago
- foobarian 3y agoI like that random fluctuation is a key part of the experiment. I would love to see more results on the nature of randomness in the universe where things like Boltzmann brains and antimatter asymmetry are a thing.
- loceng 3y agoAt first I thought this would be referencing Eric Weinstein's Geometric Unity theory, which he claims does just what the title states - which he developed over a 35 year period. I wonder if this research piggybacks or was inspired by Eric's work, whether acknowledged or not? Time will tell if their math and experiments fit in with Eric's and which is most foundational.
- edgyquant 3y agoWasn’t this theory mostly laughed off by both the industry and online? Iirc his introduction of it was claiming he was being oppressed and his theory never taken seriously
- flappyeagle 3y agoYeah EW is delusional in more ways than one
- javajosh 3y agoI have a physics degree and continue to learn about math, but in one talk I saw, Eric started off using math I'd never heard of, and didn't bother to introduce it or even motivate it's use. If he's looking for popular support, that is not the way to go about it, IMHO. But frankly it seems to me that he'd rather get the juice from claimed persecution than actually advance the field.
- loceng 3y agoRe: "I have a physics degree and continue to learn about math, but in one talk I saw, Eric started off using math I'd never heard of, and didn't bother to introduce it or even motivate it's use" So what you're saying is you don't even have the ability to start to understand if what he's saying is true, as you've not been willing to put the effort into learning the math he's referencing - that you've never heard of - and instead essentially doing high-level ad hominem saying "he'd rather get the juice from claimed persecution than actually advance the field"? Sounds to me like Eric is right about what he says about the field in general, and why there's been little to no uptake in the indoctrinated-seemingly ideological field of physics studies. I agree his tactics may be lacking, and that clearly he'll have to do a better job eventually - to handhold for people who have the capability to understand but your comment here supports the difficulties Eric states he's encountered with academia. Did you try sending him an email to ask him for more guidance? That would not only help you - whether that leads to believe he's just a charlatan or helps you learn new math - but it would be an opportunity for him to learn to be a better teacher too. Arguably the most efficient path for Eric as well, since everyone has limited time and resources, is to work with people who actually show and put in an minimally adequate effort to understanding - where connecting with him directly is perhaps the first necessary barrier to breach, so that you can have a productive conversation and at least a chance to be on the same page; and if you don't even know the math he's referencing, and can't talk his lingo, then you'd have to begin to learn the language he's speaking as a prerequisite - especially before judging him - the irony here is your ad hominem is in fact an example of persecution - and from the physics' community's mouth itself.
- scotty79 3y agoQuantum gravity always felt like instance of "if all you have is a hammer, everything looks like a nail". The novelty of this theory gives hope.
- beretguy 3y agoTo me, intuitively, it makes sense for gravity to be classical, since gravity is not a force but a curvature of space-time. I hope we see results of their tests soon.
- jerf 3y agoGravity is a curvature of space-time in the theory of General Relativity. It is not known what it will be in the final theory. It could end up being a "force" after all, or it could be that all forces are "curvatures" of a sufficiently complicated understanding of "space time", in which case force would be likely be redefined to be "curvatures" of space time anyhow, or other possibilities. It may be easier to understand this point by looking at the current theory of Quantum Mechanics, in which gravity doesn't exist at all. We are not entitled to make conclusions about gravity from that fact, since the conclusion would be "gravity doesn't exist", which is clearly false.
- DiogenesKynikos 3y agoIn General Relativity, the curvature of spacetime is affected by matter. Matter is governed by quantum mechanical physical laws, so General Relativity has to interface with quantum mechanics. To illustrate the problem: If an electron is not in a fixed position, but is rather spread over a range of possible locations (described by a wavefunction), then what is the gravitational effect of the electron? General Relativity, being a classical theory, contains the assumption that the electron's location and velocity can be precisely determined, so that its effect on the curvature of spacetime can be calculated. There's no way in General Relativity (as presently formulated) to take into account the electron wavefunction. If you start thinking about ways to interface General Relativity (GR) with quantum mechanics, you quickly realize that GR itself has to become quantum mechanical. Quantum mechanics is like a virus: once it gets into one part of the theory, it spreads everywhere. There's no way to build a logically coherent theory of the Universe that is only partly quantum mechanical. It's 100% or 0%.
- eigenket 3y agoThis is not completely accurate. The theory proposed by Oppenheim and his collaborators appears to be a consistent theory with classical gravity interacting with quantum stuff. It is subjectively rather ugly, but it does appear to be a counterexample to this 100% or 0% dichotomy.
- verisimi 3y agoProfessor Oppenheim? Dr Šoda? Professor Bose?
- Mizza 3y agoI'd love to know more about the "random fluctuations" of spacetime. I thought the only "randomness" in the universe was nuclear decay. Where can I learn more about the "random fluctuations in the curvature of spacetime"?
- K0balt 3y agoLook into Quantum foam and Casimir force. In simple terms it’s basically the physical manifestation of the uncertainty of position and energy of all matter within the universe.
- eigenket 3y agoAccording to quantum mechanics there is plenty of true randomness around. If you get an electron or ion and pass it through a Stern-Gerlach apparatus [1] or a photon and pass it through a polarising beam splitter. Then in each case you can set it up so you get the thing going in 1 off two directions with 50:50 probability. [1] https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experiment https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime...
- aport 3y agoQuestion for any physicists out there. If the theory can be tested with just a 1 kg mass on Earth, could the fluctuation in mass of GPS satellites also be detectable from their timing data?
- eigenket 3y agoI'm a physicist but not an expert in this field, but my guess would be the answer a comprehensive "no". The way satellites orbit is incredibly well described by Newtonian mechanics and there the impact of their mass on the shape/timing of the orbit is by changing the center of mass of the combined satellite-earth system. That is you only get measurable effects if the fluctuation in the mass are big enough compared to the mass of the earth.
- visionscaper 3y ago> Instead of modifying spacetime, the theory – dubbed a “postquantum theory of classical gravity” – modifies quantum theory and predicts an intrinsic breakdown in predictability that is mediated by spacetime itself. This results in random and violent fluctuations in spacetime that are larger than envisaged under quantum theory, rendering the apparent weight of objects unpredictable if measured precisely enough. I have so many questions about this paragraph; how did they change quantum theory? Are they saying that breakdown in predictability at the quantum level is actually caused by space-time? Why does this result in violent fluctuations in space-time? And why are the space-time fluctuations larger than in the case of quantum gravity?
- eigenket 3y agoSo the fundamental problem in quantum gravity is something like this (arguably). Particles with mass distort space-time (according to general relativity). Particles can be in superpositions where different parts of the superposition are in different physical positions (according to quantum mechanics). We don't know how to make gravity quantum and it seems to be difficult. So we don't have any damn clue what happens to space-time when an object with mass is in a superposition of different positions. The suggestion by Oppenheim and friends is that space-time is fundamentally classical and what happens when you put an object with mass in superposition is that random fluctuations in the space-time force the object out of superposition and into a classical random state. I.e. where quantum mechanics says you'd have a particle in a superposition of being in place A and place B, this new theory says you'd end up with a random choice being made between A and B, and it ends up in one based on something like a coin-flip. Disclaimer: I don't work on this stuff directly. My expertise is entirely that I attended a talk Jonathan Oppenheim gave at a conference last year.
- tbrownaw 3y agoWould this put a limit on how well a quantum computer (or any other large entangled system) can be isolated from its environment (how long it can be kept from decohering)? Or was a similar limit already there and this just describes it differently?
- satvikpendem 3y agoThe 1 kilogram weights previously used to define the unit have mysteriously diverged from their supposed weight [0], so I wonder if this divergence was an early sign of this theory. [0] https://en.wikipedia.org/wiki/International_Prototype_of_the_Kilogram#Stability_of_the_IPK https://en.wikipedia.org/wiki/International_Prototype_of_the...
- deleted 3y ago[deleted]
- graphe 3y ago>What is known specifically about the IPK is that it exhibits a short-term instability of about 30 μg over a period of about a month in its after-cleaned mass. The precise reason for this short-term instability is not understood but is thought to entail surface effects: microscopic differences between the prototypes' polished surfaces, possibly aggravated by hydrogen absorption due to catalysis of the volatile organic compounds that slowly deposit onto the prototypes as well as the hydrocarbon-based solvents used to clean them.
- airstrike 3y agoSee also, interestingly, https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba...
- beezle 3y agoPhysical Review X is open access so you can get the original paper for no charge at https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.041040 https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.04... Though I have a physics background, this is niche stuff.
- zeusfyi 3y ago[flagged]