11 ms·
> “We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity," And ten thousand physicists sighed d
by mabbo 4y ago
> “We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity,"
And ten thousand physicists sighed disappointingly.
- markus_zhang 4y agoJust curious but why?
- onceiwasthere 4y agoThey want an exciting disruption to current theory.
- BurningFrog 4y agoBasically they're bored/want mysteries to solve.
- zeven7 4y agotbf, there is already a mystery to solve. This just means we have no new information to help us solve it.
- ohgodplsno 4y agoWe're kind of at a dead end between both leading theories. A counterexample to either of them would mean that we got it wrong somewhere, and might help us figure out where, potentially unlocking more later. 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.
- GuB-42 4y agoSide note: Einstein didn't believe in black holes, at least initially. 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.
- _joel 4y agoMany papers/authors postulating something different to what Einstein did?
- adgjlsfhk1 4y agoGR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.
- jeremyjh 4y agoWhy would that matter at this scale ?
- markus_zhang 4y agoThanks. Can you please point me to some popular science article that explains why the two do not agree with each other?
- boschnix 4y agoI liked Sean Carroll's take on this with Steven Strogatz in the recent episode of Joy of Why. https://www.quantamagazine.org/where-do-space-time-and-gravity-come-from-20220504/ https://www.quantamagazine.org/where-do-space-time-and-gravi...
- rootbear 4y agoBrian Greene's "The Elegant Universe" does a very good, completely non-technical, job of explaining the conflict between the two theories. It then goes on to explain why String Theory is one possible solution to the problem.
- kuekacang 4y agoSometimes physicists like the theories--especially the battle-tested ones--proven wrong so that those theories needs to be refined or reevaluated. Something related to the joy of problem solving.
- mabbo 4y agoQuantum Physics and General Relativity make different predictions in specific circumstances which are beyond our ability to test to figure out which one is wrong. They can't both be perfectly correct. But in every test we can make, both seem to model reality really well. 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".
- deleted 4y ago[deleted]
- zeven7 4y agoRelatedly, before general relativity, people already knew something was wrong with Newton's theory of gravity from observing the orbit of Mercury, which didn't follow the theory accurately. At that time Mercury, being so close to the Sun, was an extreme condition that showed the flaws in the theory. The fact that general relativity continues to hold up to every observation we can make is remarkable.
- albrewer 4y agoI'd be willing to bet that the discrepancy is something that we generally consider invariant but in reality should be a ratio between two things that are very large, but get bigger or smaller at _slightly_ different rates depending on the scale or distances you're working with. 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.
- lordnacho 4y agoCould it happen that the universe simply never provides us with the required evidence? Eg if there's an anomaly but only when something that never happens happens. Like a large enough mass/charge/etc or some flavor of unlikely coincidental occurrence, like an eclipse is a bit of a coincidence.
- mhandley 4y agoAny evidence supporting general relativity at these scales is presumably also evidence in favour of dark matter actually being matter, as opposed to gravitational theory needing modification. Seems like we can still learn quite a bit from ruling out alternatives, even if it's not the quick answer we might like.
- nerdponx 4y agoWhy is that the case?
- cozzyd 4y agoWell maybe it's more evidence against MOND-like theories explaining dark matter, but those already have little buy-in nowadays.
- monocasa 4y agoThe Schwarzschild radius of a 4M solar mass black hole like Sagittarius A* is only (lol) about 7M km. Most of the MOND theories I've seen are about fall off curves at very large distances (ie. galatic scales) being more complex than GR suggests, so I'm not sure this is really proof either way. (And I say this as not a MOND adherent).
- ISL 4y agoGravitational physicist here. Every time we look in a new place and see that GR still works, it is pretty amazing. 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.
- zeven7 4y agoIt seems the common expectation is that GR is more likely to be the theory that needs to be modified the most - or more or less tossed out and replaced with a quantum theory of gravity. Is it possible that GR is just "right" and QM needs to be modified to fit into it?
- ISL 4y agoWhenever we learn more about the connections between GR and the rest of physics, the early corrections are likely to appear as "GR+new stuff" or "QM+new stuff". Both theories have enough predictive power that we'll hang on to them as effective theories for the rest of humanity's existence. 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.
- raattgift 4y agoJust to cause trouble, since we're straying far far from today's presentations (except arguably UCL's Z. Younsi in the ongoing ESO Q&A panel). :-) Can we write down the uncertainty principle in covariant form? Maybe! There is active theoretical work ongoing (e.g.) <https://arxiv.org/abs/2110.15951v2 https://arxiv.org/abs/2110.15951v2> ("... a geometric formalism for the generalised uncertainty principle which is covariant and connects features of the underlying geometry with the deformation of canonical commutator relations ... [and] an elegant interpretation for the standard dispersion relation p^2=−m^2: it describes flat spacetime in the Milne coordinates, with rest mass m giving the measure of geodesic length from origin").
- deleted 4y ago[deleted]