Is Dark Energy Weakening? (bbc.com)
- Reference: 0180467283
- News link: https://science.slashdot.org/story/25/12/28/0234206/is-dark-energy-weakening
- Source link: https://www.bbc.com/news/articles/c17xe5kl78vo
> There is growing controversy over recent evidence suggesting that a mysterious force known as dark energy might be changing in a way that challenges our current understanding of time and space. An analysis by a South Korean team has hinted that, rather than the Universe continuing to expand, galaxies could be pulled back together by gravity, ending in what astronomers call a "Big Crunch".
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> The scientists involved believe that they may be on the verge of one of the biggest discoveries in astronomy for a generation. Other astronomers have questioned these findings, but these critics have not been able to completely dismiss the South Korean team's assertions...
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> The controversy began in March with unexpected results from an instrument on a telescope in the Arizona desert called the Dark Energy Spectroscopic Instrument (Desi)... The data hinted that acceleration of the galaxies had changed over time, something not in line with the standard picture, according to Prof Ofer Lehav of University College London, who is involved with the Desi project. "Now with this changing dark energy going up and then down, again, we need a new mechanism. And this could be a shake up for the whole of physics," he says. Then in November [2]the Royal Astronomical Society (RAS) published research from a South Korean team that seems to back the view that the weirdness of dark energy is weirder still.
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> Prof Young Wook Lee of Yonsei University in Seoul and his team went back to the kind of supernova data that first revealed dark energy 27 years ago. Instead of treating these stellar explosions as having one standard brightness, they adjusted for the ages of the galaxies they came from and worked out how bright the supernovas really were. This adjustment showed that not only had dark energy changed over time, but, shockingly, that the acceleration was slowing down... If, as Prof Lee's results suggest, the force that is pushing galaxies away from each other — dark energy — is weakening, then one possibility is that it becomes so weak that gravity begins to pull the galaxies back together.
[1] https://www.bbc.com/news/articles/c17xe5kl78vo
[2] https://academic.oup.com/mnras/article/544/1/975/8281988?login=false
No such thing as dark energy (Score:2)
Dark energy, to my understanding, is the fruit of supernova observations, which seems to show expanding universe, which would then require dark energy. It is deferents and epicycles once again - more and more complex mathematical models needed to explain a false hypothesis, as new observations surface.
I hope alternative models of explaining the supernova measurements would get more attention, so that some day we could admit that this geocentric..., sorry, this dark energy model was wrong after all.
Re: (Score:3)
Like physicists are not trying to provide evidence for or disprove the dark energy model. Anyone, or more likely an international team, that does might get Nobel Prize. One experiment or analysis is not enough. One plausible theory is that dark energy is simply not constant, the constant value is an assumption, but only that.
Re: (Score:2)
> Like physicists are not trying to provide evidence for or disprove the dark energy model.
Actually, no, they are not. Meaning that dark energy is now mainstream physics, and if you dare to think otherwise, you are sidelined - very difficult to get funding for studies, or publications in peer reviewed journals. Hence, the only ones trying to prove otherwise are considered crackpots.
> One plausible theory is that dark energy is simply not constant, the constant value is an assumption, but only that.
Again, epicycles.... Instead of trying to create a mathematical model for dark energy, one can explain the supernova observations themselves with e.g. variable light speed theory (i.e. in the past light travelled slowe
Re: (Score:1)
[1]Transportation safety is an issue [youtube.com], so I oppose it.
[1] https://www.youtube.com/watch?v=7zo9PqubWSg
Re: I'm not worried (Score:2, Offtopic)
And there it is. Third comment. Every single goddamn discussion on this website.
New? (Score:5, Interesting)
Isn't this what was always predicted, the cycle of the big bang to collapse and repeating?
Re: (Score:2)
Certainly seems to fit with what I was taught in school. But, then there were news stories saying that the universe would expand forever. Some said the expansion was accelerating. Others say that the expansion is slowing.
I think it will expand for a long-ass time, and then it will contract for a long-ass time, and then singularity and then boom.
We simply need to observe it for the next 60-90 billion years and we'll have proof.
Re: New? (Score:2)
It depends on various parameters of the universe. In some parts of the space we get a Big Crunch. In others we get a Big Freeze. There's also a version called the Big Rip.
Re: (Score:2)
> There's also a version called the Big Rip.
Sounds like the version Cheech and Chong envisaged after taking a big bong rip.
Clues to what it is (Score:2)
Each observation, like ones that appear to show "dark energy" weakening, give astronomers clues that may eventually reveal exactly what "dark energy" is. Dark energy is an unknown factor, something that doesn't quite fit our current mathematical models. When you make a mathematical model, and it turns out not to exactly match physical observations, the most logical conclusion is that the mathematical model is missing something, not that there is some mystical "dark" thing out there that can't be observed. W
Re: (Score:2)
In hindsight, "dark" is an unfortunate word choice. It has always meant "unknown," not literally "dark" (as in the opposite of "light").
Re: (Score:2)
Not really unfortunate. Because the term was coined to describe something that doesn't interact with light (electromagnetic radiation). Making it difficult to observe.
Re: (Score:2)
You are referring to dark *matter* while the article here is talking about dark *energy*. But the principles are the same.
Astronomers *theorize* that "dark matter" doesn't interact with light. It could also be that the models aren't quite right, or that there's a whole lot of unexpected dust out there, or rogue plants, or some other thing or things we haven't accounted for.
Re: (Score:2)
I don't think it's just an unfortunate (unlucky) word choice. There has been a lot of speculation that this dark matter and dark energy really are unobservable. This is not just due to vocabulary.
Re: (Score:2)
It doesn't interact with ordinary matter nor the strong nor weak nuclear forces either, so it's not just light. The name "dark energy" was chosen in part to parallel the already-existing term of "dark matter." In the case of the latter, it really does mean "unknown" since dark matter might not actually be any form of matter at all, just a misunderstanding of gravity. Hence the choice of "dark" for "dark matter" was unfortunate first.
Re: (Score:2)
This.
Physicists and astronomers are often overly attached to their observations. Just try to lop a few significant figures off some measurement and watch them scream. And then someone finds a cable that wasn't plugged in properly.
Dark energy doesn't exist (Score:2)
In some higher dimensional or “brane world” models, our 3D universe is treated as a hypersurface (a brane) embedded in a higherdimensional bulk spacetime, and what we call dark energy arises from geometric properties of that embedding rather than from a fundamental vacuum fluid. for the rotation of galaxies effectively mimicking a darkmatter halo in 4D space.
Re: (Score:1)
Prove it.
Re: (Score:2)
The burden isn't on him to correct the deficiencies in your so-called theories.
Re: (Score:3)
Oh! I have a marvelous proof of this theorem which unfortunately is too large to fit in this margin.
Re: (Score:3)
Everyone and their uncle's dog has a universe model. One should be careful not to mistake mathematical structure and morphisms for actual physics.