The Nature of Space and Time · HackerPapers discussions

The Nature of Space and Time — mentioned by codethief

Mon, 10 Jul 2023 18:59:04 GMT

> 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

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The Nature of Space and Time — mentioned by codethief

Thu, 27 Apr 2023 16:54:40 GMT

My favorite "fun fact" about gravity is still this one[0]: > [Gravity] shapes the arena in which it acts, unlike other fields which act in a fixed spacetime background. From what I've seen, this fact is rather underappreciated by many of the folks doing (what they call) "quantum gravity" these days. They often try to treat gravity as a rather ordinary quantum (or string) field theory, living on a fixed background. As Hawking says in [0], "It would be rather boring if this were the case. Gravity would be just like any other field." [0]: Hawking: The Nature of Space and Time (1994), p. 2…

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The Nature of Space and Time — mentioned by codethief

Tue, 25 Apr 2023 18:32:46 GMT

> If gravity wasn't self interacting it wouldn't follow the shortest path that gravity itself creates. I don't know if this is the right way to think about this. Gravity follows all paths. In a sense, it is the path. Or, as Hawking described it[0]: > [Gravity] shapes the arena in which it acts, unlike other fields which act in a fixed spacetime background. Back to your comment: > So gravity is almost certainly self interacting. I'm confused by the "almost certainly". I think this has long been established[1], but for entirely different reasons: The Einstein field equations are highly…

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The Nature of Space and Time — mentioned by codethief

Thu, 11 Mar 2021 10:17:34 GMT

> If a photon follows a curve around a large mass, it does so because that curve is the shortest path through spacetime, if I am not mistaken. Correct! > Maybe I am missing something, but how could a quantum theory of gravity explain curvature of spacetime? […] how would a theoretical graviton explain this effect? Note that a quantum theory of gravity need not involve gravitons. The latter only appear in approaches that assume that gravity is a more or less ordinary [string] quantum field theory (QFT). Personally, I've never found this very convincing. Neither did Hawking by the way, who once…

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The Nature of Space and Time — mentioned by stochastic_monk

Wed, 14 Mar 2018 13:58:53 GMT

Many of you will be familiar with the Moore-Penrose pseudoinverse [0], a generalization of the matrix inverse which is defined for non-square matrices and zero matrices, frequently applied in machine learning and statistics. However, like Hawking, with whom he was a collaborator (as you read in the article), he also wrote several highly successful popular books. I haven't yet read the Emperor's New Mind and look forward to doing so, but I have read the excellent The Road To Reality: A Complete Guide to the Laws of the Universe [1]. I might also recommend some joint lectures between the two of…

Paper and discussion history. A mention is not an endorsement.