7 ms·
> It’s become dogma. All the other fields in nature are quantized. There’s a sense that there’s nothing special about gravity — it’s just a field like any other
by codethief 3y ago
> It’s become dogma. All the other fields in nature are quantized. There’s a sense that there’s nothing special about gravity — it’s just a field like any other — and therefore we should quantize it.
I keep on citing Stephen Hawking here on HN, but it again seems very appropriate:
> It would be rather boring if this were the case. Gravity would be just like any other field. But I believe it is distinctively different, because it shapes the arena in which it acts, unlike other fields which act in a fixed spacetime background.[0]
[0]: https://arxiv.org/abs/hep-th/9409195v1 https://arxiv.org/abs/hep-th/9409195v1
- hughesjj 3y agoI'm definitely into the "it's an emergent phenomena" camp. I think it's inherently relational, as that's a more efficient way to encode geometry rather than space itself being a quantized "thing". Afaik this theory is the "leading"/imho most promising theory of "quantum gravity", that being the "gravity = entanglement" conjecture and the related ideas of "Complexity= action/volume/whatever" that susskind and many others have been developing for the past 20 so years. All that said I'm nowhere near a physicist and am probably just spewing a total misunderstanding of the situation from my armchair. That said, I've been incessantly watching lectures in this space to try to beat an understanding into my dumb dumb brain because it's super, super fucking cool. - https://youtu.be/6_7aKoEx_kk https://youtu.be/6_7aKoEx_kk - https://youtu.be/6OpAreb779U https://youtu.be/6OpAreb779U - https://youtu.be/9crggox5rbc https://youtu.be/9crggox5rbc - https://youtu.be/OBPpRqxY8Uw https://youtu.be/OBPpRqxY8Uw - https://youtube.com/@isqg423 https://youtube.com/@isqg423 I'm also fascinated by the idea of phase transitions, which seems to be how the laws of physics have "evolved" so far. It's crazy how much quantum computation is coming into play with this stuff, ex last year's Nobel prize with the bell inequality. That said I'm sure being a programmer I'm biased to think the universe is inherently computation/math.
- EvgeniyZh 3y agoThere are some pretty strict limitations on emergent phenomena, like Weinberg–Witten theorem. It doesn't rule out emergence of gravity but it makes it less likely
- hughesjj 3y agoTo my understanding that's only if you're trying to quantize the graviton as an emergent particle. I'm personally of the belief that spacetime itself is an emergent phenomena https://en.m.wikipedia.org/wiki/Composite_gravity https://en.m.wikipedia.org/wiki/Composite_gravity
- ethn 3y agoIt's not relational. There's several rigorous proofs against Spinoza's relational theory. Namely that of Kant and Einstein: "even if space is composed of nothing but relations between observers and events, it would be conceptually possible for all observers to agree on their measurements, whereas relativity implies they will disagree" [0] 0: https://en.wikipedia.org/wiki/Relational_space https://en.wikipedia.org/wiki/Relational_space
- ImHereToVote 3y agoUnless one of the observers accelerates for some reason. Now his observation is privileged.
- lgas 3y agoDoesn't relativity mean there's no difference between that observer accelerating in one direction and everything else accelerating in the opposite direction? So wouldn't everyone's observation be equally privileged? I'm asking honestly as am (obviously) not a physicist.
- ImHereToVote 3y agoYou would think so, but no. There is something magical about acceleration, specifically how much spacetime you increasingly or decreasingly traverse.
- nomel 3y ago> it’s just a field like any other — and therefore we should quantize it. So, trade dogma for tradition!
- skinner_ 3y agoI believe you are misparsing that sentence. The dogma and the tradition are the same thing.
- gerdesj 3y agoDogma and tradition are two very different concepts. Dogma is forced down from "above" and tradition is consensual. Tradition is "organic", dogma is proscribed. Tradition: "We chase a wheel of cheese down Coopers hill in Gloucestershire and invite severe injury, for a laugh" - won by a somewhat concussed Canadian lass this year, well done her. https://www.theguardian.com/food/2023/may/29/woman-wins-coopers-hill-cheese-rolling-race-despite-being-knocked-out https://www.theguardian.com/food/2023/may/29/woman-wins-coop... Dogma: "This is what we believe". Here is an example - https://www.catholicnewsagency.com/resource/55423/the-four-marian-dogmas https://www.catholicnewsagency.com/resource/55423/the-four-m... Dogma is a religious thing. Originally Catholic but seems to have spread further. Tradition is something that is done because that is how it was done. "Was hal" - be you hale ... that's where "wassail" came from.
- drdeca 3y agoSkinner_ is saying that the description which nomel interpreted as describing "an alternative to the thing being called dogma" and as "tradition", was a description of the thing being described as "dogma", and not, as nomel interpreted, as an alternative thing to the thing that the quote was considering "dogma".
- mensetmanusman 3y agoDogma is tradition formalized.
- prometheus76 3y ago
- miga 3y agoWhy would gravity behave different than Higgs field?
- krastanov 3y agoAny reason you are specifically picking the Higgs field in your question? I am asking, because this sounds a bit like you are riffing on a common misconception that the Higgs field has something to do with gravity, which is not the case. The interaction with the Higgs field is the reason some (only some) of the particles have a mass, but explaining gravity does not need to have anything to do with the Higgs field. But yeah, it is fair to ask why gravity should behave any differently than any other quantum field -- in the context of Quantum Field Theory (one of the two incredibly successful theories of physics) that is a great question. One handwavy reason it seems different is that in General Relativity (the other incredibly success theory of physics), gravity has to do with the geometry of space and time, not with what other fields exist in that space and time (and as such is explicitly different than the other fields).
- pravus 3y agoMy understanding is that the Higgs field should be simpler than gravity because it's just a static value whereas gravity is SU(1)? At least to me it seems logical that if the Higgs is quantized, surely more complicated fields would be as well?
- 26fingies 3y agothe way the quote reads it sounds like this physicist is saying that gravity is not a field at all.
- drdeca 3y agoSU(1) is the trivial group. SU(n) is the group of unitary nxn matrices with determinant 1. There is only one 1x1 unitary matrix with determinant 1, and in fact there is only one 1x1 matrix with determinant 1 period, namely, the 1x1 matrix whose only entry is the number 1. So, to associated something with a symmetry group of SU(1) would be effectively the same as not associating it with a symmetry group.
- Aardwolf 3y agoIf gravity is not quantized, would that not mean that it has infinite information (the accuracy to represent its values to infinite digits of precision), and thus cause a black hole due to such high information density?
- chownie 3y agoIs that not what it does?
- mr_toad 3y agoGeneral relativity requires singularities, QM prohibits them. It’s a puzzle.
- XorNot 3y agoKeep in mind in GR singularities don't really make sense either: i.e. when you pass the event horizon of a black hole, under GR the rules say that you must always been traveling towards the singularity. But the corollary of this is that it's not actually possible - mathematically - to arrive at the singularity (because then you'd be moving parallel with it rather then towards it). So while we can define what happens very well under GR for the "most" of the inside of a black hole, we can't actually explain what happens to objects which reach the center. There has to be some type of discontinuity whatever happens - i.e. if the object disappears, that's still a discontinuity even if it would resolve the paradox. EDIT: Which is of course where GR and QM need to reconcile as well - as you get infinitely close to the singularity, the size scale is getting small enough that QM should be well in play.
- onesphere 3y agoIn General Relativity, matter curves spacetime, so instead of saying that all the “other fields” act within spacetime, perhaps “the metric [tensor] is determined by the matter and energy content of spacetime?” If geometry is described fully with a (tensor) field, perhaps we’re really just looking for a gauge theory but then that would be QM. Now I’m trying to imagine a tensor computing some infinite curvature supposedly necessary in GR.
- pyinstallwoes 3y agoPerhaps it’s a fictitious force just like centrifugal motion and otherwise. :)