Part of this is the fact that everyone in the field works very hard to find a crack in GR's armor, and so far it has resisted everyone.
The other part is that GR has a romantic beauty to it, both in structure and in predictions. Each time GR matches reality in a new context, the feeling is akin to watching a beautiful sunrise on a summer's morning. You've seen it before, but darn if it isn't pretty.
(That's counterbalanced with the tears shed over your midterm grades.)
That's beautifully worded. It brings up the respect scientists can have for one another's work (in the best case scenarii, let's skip the bad seeds for a moment).
Everyone is different, but most scientists seek areas where experiment doesn’t match the predictions. It’s the only way we learn.
One such instance is the W Boson Anomaly: https://vm.tiktok.com/ZTdpwrmoj/?k=1
If the equations were right, the experimental error would be zero (modulo uncertainty bars). Instead, we’re quite confident the standard model is wrong (or “incomplete” to phrase it diplomatically).
As an aside, this is also a great example of TikTok turning a corner. I now have 184 educational videos saved, along with dozens of science videos. I learn more on TikTok than any other source now, which I didn’t expect. There’s an avid physicist community, and I made friends with someone who works at CERN. https://twitter.com/simoneragoni?s=21&t=xIkxhA--TzKDWA5XN3ve... Get ready for TikTok to become the new Wikipedia within a decade.
I too have been surprised with the amount of genuinely educational and interesting material on TikTok. It won't replace Wikipedia but it's a great companion to it.
I've also learned a lot from TikTok, where short form content has led to 30 second tutorials that leave 30 minute YouTube equivalents in their dust. My learning topics include smartphone photography, wood working, and knots. I was also surprised at how informative it can be.
It'll be interesting to see how TikTok's content moderation compares against Wikipedia. We won't have notability wars, but there is massive scope for disinformation and banal wrongness.
That said, the mathematical fundamentals of GR do not directly incorporate notions of the uncertainty principle. That fact alone, I believe, means that GR is an incomplete description of space/time/physics.
We have a lot more to learn about gravity, especially at laboratory scale and smaller.
While we can only measure G to ~10 ppm, the equivalence principle has been tested at the 10^{-14} level (and ~10^{-9} at meter-scales). The EP is the property that makes gravity really special and simultaneously the thing that makes gravity hard to test.
The core assertion that all things fall the same way is axiomatic to GR and has been very well tested. We have everything left to learn about gravity, but at the same time, GR has held up far better than it "should" have against a battery of really great experiments.
I have been thinking about this off and on since reading your comment. Is it really the structure that is beautiful, or is it that we can convert a large wall of symbols[3] into about eight easily memorized ones? That is, is it the notation that is beautiful, rather than the calculations it describes?
Relatedly:
> ... and in predictions. Each time GR matches reality in a new context, the feeling is akin to watching a beautiful sunrise on a summer's morning.
But how does one get predictions?
If you use white chalk on a blackboard to write down the constraints, boundary conditions, a realistic stress-energy (like, oh, anything satisfying Klein-Gordon or the way Weinberg writes down Belinfante), and so forth, to actually capture a realistic physical system in our universe (with actual broken global symmetries), the chalkboard's albedo sure gets higher. I'm certain you know this, and within an hour or two would go reaching for Etk/Cactus or even NRPy+/SENR. :-) And I haven't even gotten into things like Israel Junction conditions and other approaches to more-than-one-source problems.
I agree that conceptually GR is (or really, the EFEs are) amazing, and that it's a nice sandbox (oh the fun you can have in a (-,+) or (+,+,+,+,+,+,+,+,+,+,+,+,...,+) spacetime! Or Misner's mixmaster! Or lots of the entries in <https://www.cambridge.org/core/books/exact-solutions-of-eins...>), but when it comes to doing (and especially intuiting[1]) actual physics maybe familiarity breeds frustration or something. It is wonderful that the "sandbox" can, with effort and additional details (NS EoS, say), grind out astrophysical, cosmological, and even laboratory observables.
> darn if it isn't pretty
Darn if it isn't impressive how much work (including observation/experiment) went into the matching. :-)
- --
[1] Is it sharp enough to cut paper? Your answer to the question about the "sharpness" (in a different sense) of the event horizon got me wondering about extended objects, like what happens to a tissue-paper space capsule on a hyperbolic orbit grazing the point of no return, if a tiny corner of the space capsule is allowed to dip below it? Does it tear? Does it drag the rest of the capsule in, even though a good sneeze could rip its structure apart? Is the answer <https://en.wikipedia.org/wiki/Mu_(negative)> because of the nature of the horizon?
I started scribbling on this, then decided I really wanted to pretend the Weyl curvature tensor away so started thinking of really really massive BH -> Rindler approach (hoping Egan [2] had done the work already), abandoned that (because I don't think it works in general -- binding energy even in tissue paper might raise a "bump" (and thus tidal forces) on the BH horizon but I don't see how that works for the Rindler horizon, and I don't really trust intuitions built on staticity), and so on.
So, maybe I'm being a bit dumb at the moment, but a simple "what if?" turned into an "I have no idea" in spite of reasonable working knowledge of GR and some ideas about how to get the idea (with a sinking feeling that anything I arrive at is going to annoy me even more than not knowing at all, especially when trying to make sense of "no drama").
I dunno: something so hard to work with doesn't (to me) evoke romance. It's more like the feeling of summoning a cat who really doesn't want to come until your pspspspsing arrives at an acceptable-to-the-cat approximation of cat food being dispensed.
[2] http://www.gregegan.net/SCIENCE/Rindler/RindlerHorizon.html ("a constantly accelerating observer in flat spacetime trailing an object behind them")
[3] For anyone who has stumbled upon this rant and who has never seen anything like the full horror, check the tip of the iceberg at <https://profoundphysics.com/einstein-field-equations-fully-w...> (eyeballing just that page, things look reasonably OK; I have not really looked at anything else on that site).
[4] Oh, "Contritutions" (sic). <http://einsteintoolkit.org/guidelines.html> I'm starting to feel better now.
The best place to look for new data where we might find reality disagreeing with either model is in the extreme parts of the universe, like black holes. If there was even a hint in this photo that General Relativity wasn't perfectly accurate, we might be able to take the discrepancy and build a new model that solves the disagreement.
Whoever does that gets a Nobel Prize and has their name as immortalized as "Einstein".
The fact that general relativity continues to hold up to every observation we can make is remarkable.
Granted, I only ever got as far as E&M physics in college so I could be way off here but that scenario has turned up so many times in history.
This is a semantic nitpick, but I don’t think it’s useful to think of these theories as “wrong”. They are both models that make predictions about physical phenomena that, when tested, are extremely accurate. They provide incomplete and inconsistent predictions of what happens at the very edges of physical reality, and they need reconciled.
It might just not be possible to see anything odd without having a black hole right there to study, but there’s always hope that the next new observation will provide a clue as the previous ones repeatedly have not.
https://gizmodo.com/why-cant-einstein-and-quantum-mechanics-...
https://www.theguardian.com/news/2015/nov/04/relativity-quan...
https://en.wikipedia.org/wiki/Problem_of_time
https://physics.stackexchange.com/questions/387/a-list-of-in...
For a good general source if you want to learn a lot more from a good popular science point of view (but one that takes great care to not accidentally mislead by oversimplification as often happens with popular science) about general relativity and quantum mechanics, try PBS Space Time, especially after Dr. Matt O'Dowd took over as host and main writer.
I'll add an additional recommendation: Stephen Hawking - The Theory Of Everything
https://www.quantamagazine.org/where-do-space-time-and-gravi...
Black holes are a solution to the general relativity equations, but Einstein thought they were just a mathematical quirk, and that in real life, they wouldn't have been able to form.
So ever time someone says "Einstein was right" when talking about black holes, then no. He was right about general relativity, but he was wrong about the existence of black holes.
You wouldn't be surprised if your door opened just as usual when you put your key in the lock. The day it starts jamming however, you get very interested.
And ten thousand physicists sighed disappointingly.