[Maro]

Are you a physicist? Not trying to be snarky.

I think GR is at Newton's level. They say most of Physics is very iterative, and if X didn't discover Z, the probably another person Y would have 5-10 yrs later. But this is not true for GR. GR came out of the blue, it wasn't strictly required to explain anything important back then. It was just Einstein sitting down, doing thought experiments about elevators in space, then a huge, incomprehensible (to me) mental leap to manifolds and tensors, and the Einstein equation. You can try this yourself: read his popular GR book (it's excellent), then pick up a GR textbook and read the first chapter, and see if you could get from the thought experiments to constructing the math.

It's hard to compare it to Newton, bc Newton also had to invent Calculus, but it's up there.

[T-A]

This is actually the subject of a long-running dispute. Fun fact: Hilbert submitted a paper with the field equations of GR before Einstein - but it was published later.

https://en.wikipedia.org/wiki/Relativity_priority_dispute#Ge...

[cyphar]

> Are you a physicist? Not trying to be snarky.

Yes, I've studied and done physics research (I have yet to finish my degree, but I've completed all of the physics topics). (My research topics were on astroseismology and non-linear optics -- not related to SR or GR, but we went through the derivations and reasoning of SR in class.)

> I think GR is at Newton's level.

I think you've misunderstood what I meant by "people over-complicate Einstein's work". My point wasn't that Einstein is somehow inferior to Newton, it was that a large part of Einstein's work is actually incredibly simple (compared to how it is pitched) which to me makes it all the more genius.

> GR came out of the blue, it wasn't strictly required to explain anything important back then.

The core idea behind GR came from thought experiments trying to understand how SR might be extended to non-inertial frames. In many ways this is the most obvious thing to consider after you've come up with SR: "what if we start accelerating?"

Also, SR similarly wasn't required to explain anything important. Einstein was thinking very deeply about what does it mean to "measure" something, and the first section of his paper was discussions of synchronized clocks and how they relate to measurements (possibly the furthest thing from a "real" problem you can have).

> then a huge, incomprehensible (to me) mental leap to manifolds and tensors, and the Einstein equation.

In Einstein's case, he had quite a bit of help with the mathematics (again, not to detract at all -- but we should separate the mathematical derivation from intuition). Intuition is the driving force in physics (with mathematics fleshing out what the logical conclusion of an intuition must be), and so I find discussing the intuition to be far more critical when talking about physical theories.

The core genius was the realisation that acceleration changes how light beams look to observers -- and the intuition that acceleration must have an equivalence to gravity. Neither of these things are complicated, and you could explain them to anyone who has seen a projectile or stood in an elevator. But the conclusion you come to is far from obvious.

And that, to me, is the beauty of physics. Obviously the intuition is just the first step, and there is plenty of brilliance in all of the manifold and tensor equations (it's definitely above my pay-grade), but I think that over-hyping the mathematics isn't quite right either.

> It's hard to compare it to Newton, bc Newton also had to invent Calculus, but it's up there.

That is effectively what I was saying. Newton had Principa Mathematica and in many ways pioneered the mathematical viewpoint that we use in physics today.

[meekaaku]

"SR similarly wasn't required to explain anything important"

Wasnt it the case that no one was able to explain Michaelson-Morley experiment? That speed of light was measured to be the same irresective of observer speed? Ppl came with all sorts of explanations (ether/lorentz tx etc), but it was Einstein who had the creativity to suggest that maybe time itself was slowing down. With that insight, the rest was beautifuly derivable.

And this is also why, Hilbert was able to (and otherws were racing to) derive the field equations before Einstein, since Einstein needed help from mathematicians (Grossman?), and Hilbert was an already excellent mathematician. SR and GR is derivable from beautifuly simple insights (time slowdown, gravity/acceleration equivalence).

One could say Einstein came with this insight out of the blue, but Poincare was also investigating time dilation, but stopped because it was too counter-intuitive.

Edit: typos

[Maro]

"SR similarly wasn't required to explain anything important"

I don't agree. The Maxwell equations (1865-1875) already implicitly encode the Lorentz transformation as the symmetry group, that's one of those "sooner or later somebody would have come along and put a spacetime theory behind it" thing, in this sense it's not up there with Newton. As you probably know there were a bunch of physicists who were looking at this (eg. Lorentz, Poincare, Larmor, etc). Then it was Einstein who tied it all together, and it was called the Special Theory of Relativity. (But this is one of those cases where this was going to happen anyway.)

I agree that Einstein was able to borrow manifolds and tensor calculus from the mathematicians, unlike Newton, who had to invent everything.

Btw. this is a great discussion.

[posterboy]

> read his popular GR book (it's excellent)

No it's not, "and that, my friend, you will surely believe me".

[Maro]

Not sure what you mean here.

I mean this book: https://www.amazon.com/Relativity-Special-General-Albert-Ein...

It's excellent.