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Comment by mr_mitm | Hacker News Reader

It's also remarkable that the mathematical tools required for GR were developed just in the few decades before Einstein wrote down his equations.

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One way to view things is that GR was obvious to a smart person with good enough tools and that if Einstein wouldn't have discovered it someone else would have soon after.

Of all the physical theories, general relativity is probably the one that's least likely to be true of. Because it just wasn't needed in all its generality at that point of time. Instead of going from first principles like Einstein some other physicist could have developed it from the other end, and made corrections to Newton mechanics based on the observed precession of Mercury and the deflection of starlight by the Sun (if someone would have done that observation without the impetus of GR). It could have been akin to how quantum theory in its first 25 years was a collection of ad-hoc explanations of various phenomena using the quantized energy idea but having no generalized theory of them.

We'd have found out for sure when we first built a GPS system without relativity correction. It wouldn't work and that experimental error would have to be explained somehow and that in turn would lead to the discovery of GR if it had not been discovered through some other means at that time.

Quantum mechanics and relativity are both explanations of the interferometer from Michelson-Morley.

Which turns out to work, now called LIGO, if you apply relativistic and quantum corrections.

David Hilbert, for one, was apparently close. That said, I feel that it is a bit of a stretch to call it obvious (maybe more obvious in the sense of "this is the way to go" rather than that the answer was obvious.)

From what I remember, Hilbert actually got the equations first by applying the principle of least action, so a much more mathematical than Einstein's physical approach. However, everybody agreed that Einstein did all the heavy lifting (he worked closely with mathematicians for years to figure things out), so that's why they aren't called the Einstein-Hilbert equations.

Least action is a very physical approach?

Not compared to how Einstein derived the equations

Hmmm, when I studied GR, the consensus was that it came out of nowhere and if it wasn't for Einstein's genius, it would have taken at least a long time until someone else had discovered it. But you make a good point. Ultimately it's an unanswerable question, I guess.

When I studied GR my professor said that Maxwell was close and had he not died young it would’ve been him.

Yeah there’s definitely some singularity like stuff happening. While we don’t see visibly dramatic evolutions like GR happening, we are making incredible strides on unsolved problems and extravagantly complex discoveries at a blistering pace, so much so that they’re not noteworthy any more.

Very true.

From the perspective of something like a Tardigrade we are definitely well into a “singularity”.

From the perspective of a rock the Tardigrade itself is matter experiencing a “singularity”.

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