from Hacker News

Scientists say they may have detected dark energy

by Osiris30 on 9/16/21, 11:25 AM with 62 comments

  • by mabbo on 9/17/21, 2:45 PM

    This is neat, but I would take it with so many grains of salt.

    We don't know what dark matter is. We have some ideas. XENON1T was/is testing some of those theories about dark matter.

    We know next to nothing at all about dark energy. We're pretty sure it's a thing, or else our model of the universe is just completely wrong and it's not anything at all.

    So if XENON1T finds something that doesn't fit their model of dark matter, going on a limb and saying "I dunno, maybe it's dark energy?" is a fun thought experiment and model, but at best it might lead to further experiments to see how likely that model is to be true. And from what I'm reading, that's the attitude the scientists behind XENON1T are taking here.

    But alas, we all know that tomorrow we can expect pop-sci articles saying "DARK ENERGY HAS BEEN SOLVED".

  • by raattgift on 9/17/21, 2:50 PM

    The original text which the link at the top simply duplicates minus the hyperlinks is at :

    https://www.cam.ac.uk/research/news/have-we-detected-dark-en...

    which links to the open access paper at Phys.Rev.D :

    https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.0...

  • by eterevsky on 9/17/21, 3:17 PM

    I would bet at 10 to 1 rate that this will turn out not to be dark energy. We haven't observed any dark energy effects with scales less than billions light years. I would've been much less skeptical if they announced that they found dark matter.

  • by tppiotrowski on 9/17/21, 3:38 PM

    > About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an accelerated rate.

    I understand that matter slows and energy accelerates the expansion of the universe but how is this ratio calculated? It seems like we would need to know the strength of dark energy to arrive at this reasoning.

  • by dirtbag__dad on 9/17/21, 4:10 PM

    This article was a breeze to read. (As opposed to the complicated scientific abstracts I usually give up on after a few paragraphs.)

    Anyone have recommendations for approachable coverage of science journals and news?

  • by jjtheblunt on 9/17/21, 4:46 PM

    "may" -> subjunctive mood verb -> usually turns out false when in headlines, it seems

  • by paulpauper on 9/17/21, 2:40 PM

    This is why I don't belive there is scientific stagnation. New discoveries and theories are constant being made and proposed. Its only because the problems have gotten harder that progress seems slower.

  • by snambi on 9/17/21, 4:13 PM

    Are the scientists not sure?

  • by verytrivial on 9/17/21, 3:06 PM

    "detected dark energy" Ooo! This could be really interes--

    "(phys.org)" .... Oh. Expectations adjusted accordingly.

  • by mcguire on 9/17/21, 5:51 PM

    I haven't been following cosmology very closely in a while; could someone update my knowledge a bit?

    * The only evidence for dark matter is that galaxies and galactic clusters are moving faster than they should be; i.e. they are acting like there is more gravitational mass around.

    * The only evidence for dark energy is that the redshift of distant objects is higher than it should be; i.e. they seem to be accelerating away rather than decelerating.

    * All of the other properties of dark matter and dark energy are negative: we have not been able to observe anything, so we know what it's not.

  • by peter_retief on 9/17/21, 5:43 PM

    Right, I wouldnt hold my breath about the dark matter theory. It is up there with alien space ships and santa.

  • by aszantu on 9/17/21, 6:48 PM

    I just thought: if fusion makes heavier elements, it makes sense that the universe expands faster... And I don't even know how I got there...

    fusion makes elements heavier.

    Heavier collections of elements make more gravity.

    (is the creation of matter limited in our universe?) In bucket with limited supply of new matter, through fusion the existing matter makes clumps which get heavier and heavier. But the substrate will thin everywhere else.

    Supermassive black holes make more gravity.

    The more compression there is, the more heat is generated,

    And matter switches state at some point. (solid -> gaseous -> plasma -> another step -> another step?)

    If the matter "becomes" dark energy as a new sort of state, it could get "flung" out like two electrons with the same poles.

    Since Energy doesn't get lost, there's no other way than to "collect" at the fringes of the universe

    If the universe was like a baloon in the universe it would push the boundaries of the bucket indefinitely.

    Gravity is kinda like our substrate, not sure if fish are aware about their water being "heavier or less heavy", not sure if this analogy will ever hold up...

    can someone let me know if I got some of it right?