Re:New research: Dark Energy might not exist after all
by astro123 on Thursday November 28, 2019 @09:07PM
(#21661458)
Not to go into much detail, but these author's views are not shared broadly in the cosmology community. There was a recent paper [1] put on the arxiv that talked a bit about this. I'm not an expert on supernova cosmology (I work on cosmology using other methods) but people I know who are experts claim there are issues.
There are also a ton of other reasons to think that the universe is flat (see the CMB [2]) and to think that there is dark energy (large scale structure [3]).
We still have no idea what DE is and it might not be an "Energy" but rather some modification of gravity or something else. But we're pretty confident in the phenomenology - there is something there that appears to be pulling things apart.
Re:New research: Dark Energy might not exist after all
by ic147 on Friday November 29, 2019 @05:13PM
(#21667141)
I find it funny that a nearly identical comment (different wording, but ssame joke and no follow-up) in this thread hasn't been receiving the same negative attention.
Re:New research: Dark Energy might not exist after all
by jbotz on Friday November 29, 2019 @05:30AM
(#21663502)
Sorry, but the article you linked says nothing about "reversing the results" of the OP article, it is about the same research as the OP article... Which at best you might say reverses the results from the 90s which originally found acceleration of cosmic expansion.
Re:New research: Dark Energy might not exist after all
by empath75 on Friday November 29, 2019 @08:23AM
(#21664189)
According to Riess, however, the supernovae data used by Sarkar’s group are out of date. He says that he and some colleagues, including D’Arcy Kenworthy of Johns Hopkins University, plugged data from a sample of about 1300 supernovae with lower systematic uncertainties into the model used in the latest work. The results, he says, were unambiguous, with the existence of a dipole rejected at more than 4σ and cosmic acceleration confirmed at over 6σ.
More importantly, says Riess, the objections against Sarkar and colleagues’ original statistical analysis still stand, as do the criticisms of neglecting other data. “The evidence for cosmic acceleration and dark energy are much broader than only the supernovae Ia sample, and any scientific case against cosmic acceleration needs to take those into account,” he says.
Re:New research: Dark Energy might not exist after all
by jbotz on Friday November 29, 2019 @11:45AM
(#21665327)
Oh yeah, toward the end of the article it does mention that... but those results by Adam Riess are unpublished, so it's just a spurious claim by a guy with a lot of vested interest for now.
Re:New research: Dark Energy might not exist after all
by empath75 on Friday November 29, 2019 @01:13PM
(#21665888)
Why do you think he has a vested interest? If he could get similar, convincing results on a larger data set, that would be a career-making paper. It’s not like there is a dark energy industry trying to cover up a hoax.
Re:New research: Dark Energy might not exist after all
by jbotz on Monday December 02, 2019 @05:14AM
(#21681233)
"Vested interest" doesn't have to be financial. They are not going to take away his Nobel price if it turns out that the expansion of the Universe is not accelerating, but nobody wants to spend the rest of their life saying "I got a Nobel price for X, but it turns out X was wrong." That's some pretty heavy psychological "vested interest", I think.
Re:New research: Dark Energy might not exist after all
by joe_the_user on Thursday November 28, 2019 @08:24PM
(#21661278)
OK, looking at the comments, I have to note that Dark Matter[1] and Dark Energy[2] are two different but related hypotheses. The basic existence of Dark Matter is on a fairly strong footing experimentally and afaik this article doesn't cast doubt on its existence (it has been observed, on the cosmic scale, as accurately as many form ordinary matter, for example). Again, this is the dark energy issue. Just sayin'
Re:New research: Dark Energy might not exist after all
by gus_massa on Friday November 29, 2019 @01:23PM
(#21665932)
Another important difference is that:
Dark Matter is not uniformly distributed, for example if forms big blobs that surround the visible parts of the galaxies.
Dark Energy is uniformly distributed, but the (equivalent?) density is very small, so the effect is important in the very empty space between galaxies.
Re:New research: Dark Energy might not exist after all
by LessDmesg on Friday November 29, 2019 @08:44AM
(#21664296)
As my physics lab teacher taught us, all breakthroughs in physics happen after new better measuring instruments become available. Modern cosmology is starved of such new equipment, hence devoid of any real progress, having to wallow in theoretical bogmires instead. I would suggest all those funds and scientists be instead diverted to researching nuclear fusion, which is the more pressing goal for humanity right now.
Re:New research: Dark Energy might not exist after all
by edw on Thursday November 28, 2019 @08:16PM
(#21661236)
Intuitive appeal is overrated. Aristotelian physics (motion derives from continuous application of force) was intuitive to a lot of people for a very long time. And then Galileo came along.
Re:New research: Dark Energy might not exist after all
by NikolaeVarius on Thursday November 28, 2019 @08:24PM
(#21661284)
Not the best example, Galileo argued plenty from positions he saw as intuitive, even though he was completely wrong.
Also, according to the physics of the day, its completely understandable as to why they thought that way, intuition comes from observing nature, even if those observations may be incorrect simply from not being able to gather the data properly.
Re:New research: Dark Energy might not exist after all
by knzhou on Thursday November 28, 2019 @10:20PM
(#21661752)
It's not about first impression intuition. I'll bet you'll find relativistic quantum field theory less intuitive, at the popular level, than either string theory or dark energy -- but it has more empirical support than almost anything else in physics.
Re:New research: Dark Energy might not exist after all
by knzhou on Thursday November 28, 2019 @10:18PM
(#21661742)
It was an application of Occam's razor. Dark energy arises automatically in the Standard Model. That is, you don't put it in by hand -- it emerges no matter what you do. In fact, we often get too much of it; this is the cosmological constant problem.
There are also a ton of other reasons to think that the universe is flat (see the CMB [2]) and to think that there is dark energy (large scale structure [3]).
We still have no idea what DE is and it might not be an "Energy" but rather some modification of gravity or something else. But we're pretty confident in the phenomenology - there is something there that appears to be pulling things apart.
[1] https://arxiv.org/pdf/1911.06456.pdf [2] https://physics.stackexchange.com/questions/439535/why-does-... [3] https://www.darkenergysurvey.org/supporting-science/large-sc...
Of course this is totally different than saying it is 2D flat. We know this because of cats.
The issue isn't humor, it's lame humor, which is the kudzu of the internet.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...
Downvotes are just saying that maybe that comment wasn't welcome in this thread not that you aren't in any thread.
It's a much cleaner downvote than those against controversial, but thought out opinions.
According to this article, using the model from this paper with more up to date data sets completely reverses their results.
I would love to see a PBS SpaceTime video explaining all of this. They do a fantastic job with new papers such as this one.
More importantly, says Riess, the objections against Sarkar and colleagues’ original statistical analysis still stand, as do the criticisms of neglecting other data. “The evidence for cosmic acceleration and dark energy are much broader than only the supernovae Ia sample, and any scientific case against cosmic acceleration needs to take those into account,” he says.
[1] https://en.wikipedia.org/wiki/Dark_matter [2] https://en.wikipedia.org/wiki/Dark_energy
'Dark Energy' is physicist code for: anti-gravitating non-stuff that we cannot see.
(i.e. Dark Energy, aka Einstein's Cosmological Constant, is a property of the vacuum.)
Dark Matter is not uniformly distributed, for example if forms big blobs that surround the visible parts of the galaxies.
Dark Energy is uniformly distributed, but the (equivalent?) density is very small, so the effect is important in the very empty space between galaxies.
https://news.ycombinator.com/newsguidelines.html
https://news.ycombinator.com/newsguidelines.html
Also, according to the physics of the day, its completely understandable as to why they thought that way, intuition comes from observing nature, even if those observations may be incorrect simply from not being able to gather the data properly.
Who awards these Nobel Prizes, anyway?
(My first thought when I heard about this Dark Energy thing was, "which part of Occam's Razor don't you get?")
https://news.ycombinator.com/newsguidelines.html
Well, you would know.
Papers published anyway.
It's easy to sit back and feel smug because physicists might be wrong -- but it's impossible to do anything worthwhile without taking on that risk.
It could be. Confirming results is part of the scientific process.
Of course, very little ever meets that description.