I am not remotely qualified to understand this letter. https://academic.oup.com/mnrasl/article ... 55/7926647
Does it mean that general relativity accounts for “dark energy”?
The end of dark energy?
The end of dark energy?
where once I used to scintillate
now I sin till ten past three
now I sin till ten past three
Re: The end of dark energy?
At first glance, it conflicts with the large amount of cleaner CMB evidence.
Re: The end of dark energy?
There's lots of evidence that our cosmological models are wrong. This is just another piece. Whilst these authors show that an alternative theory explains one particular anomaly better than the standard cosmological model, there's lots of other problems. So I'm not convinced that this is anything different from the general well known issue.
Meanwhile, we have recently found evidence of general relativity breaking down in some cases, as Sabine H (youtube 7 mins) explained a few weeks ago. This isn't such a surprise. There are some fundamental reasons for thinking that relativity should break down in extreme situations, which is why people have been looking hard for it. But it potentially warns against looking to relativity as a fix for other stuff that doesn't work.
Then there is the issue that maybe you can't even represent the generality of physics with maths. Sabine H again (youtube 7 mins) describes recent work showing that some physics measures are uncomputable. My initial reaction to that is that lots of stuff is uncomputable, and it isn't generally a big issue.* For example, not quite the same thing, but the Navier-Stokes equations which describe the motions of fluids are - in generality - intractable, but that's not such a huge problem. But raises the possibility that there may not be a mathematical description of some more extreme stuff, which might be the reason why we haven't been getting anywhere with fundamental theoretical physics since about 1990.
*(footnote for people with enough maths) Essentially, these uncomputability issues tend to come down to the observation that quantity of true things in a formal mathematical system is uncountably infinite, but the number of constructions or proofs in such a system is only countably infinite. So there is an uncountably infinite number of true things you can't prove/construct within a formal mathematical system. But, rather like the paradoxes arising from the axiom of choice/Zorn's Lemma, these unconstructable things are mostly so artificial or unphysical as to be irrelevant. But we already knew of some more normal looking things that are uncomputable, but even those don't frighten the horses.
Meanwhile, we have recently found evidence of general relativity breaking down in some cases, as Sabine H (youtube 7 mins) explained a few weeks ago. This isn't such a surprise. There are some fundamental reasons for thinking that relativity should break down in extreme situations, which is why people have been looking hard for it. But it potentially warns against looking to relativity as a fix for other stuff that doesn't work.
Then there is the issue that maybe you can't even represent the generality of physics with maths. Sabine H again (youtube 7 mins) describes recent work showing that some physics measures are uncomputable. My initial reaction to that is that lots of stuff is uncomputable, and it isn't generally a big issue.* For example, not quite the same thing, but the Navier-Stokes equations which describe the motions of fluids are - in generality - intractable, but that's not such a huge problem. But raises the possibility that there may not be a mathematical description of some more extreme stuff, which might be the reason why we haven't been getting anywhere with fundamental theoretical physics since about 1990.
*(footnote for people with enough maths) Essentially, these uncomputability issues tend to come down to the observation that quantity of true things in a formal mathematical system is uncountably infinite, but the number of constructions or proofs in such a system is only countably infinite. So there is an uncountably infinite number of true things you can't prove/construct within a formal mathematical system. But, rather like the paradoxes arising from the axiom of choice/Zorn's Lemma, these unconstructable things are mostly so artificial or unphysical as to be irrelevant. But we already knew of some more normal looking things that are uncomputable, but even those don't frighten the horses.
Re: The end of dark energy?
I think the claim is that clocks run faster in the voids between clusters of galaxies - which is a consequence of GR. This could explain the apparent acceleration in the cosmic expansion rate that is currently attributed to 'Dark Energy'.Grumble wrote: ↑Mon Dec 23, 2024 9:52 amI am not remotely qualified to understand this letter. https://academic.oup.com/mnrasl/article ... 55/7926647
Does it mean that general relativity accounts for “dark energy”?
I'm not in a position to judge the interpretation of the data
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
Meta? I'd say so!
ETA 5/8/20: I've been advised that the result was correct, it was the initial interpretation that needed to be withdrawn
Meta? I'd say so!