6 ms·
Has the hidden matter of the universe been discovered?
- Cancan82 6y agoIs this different than dark matter? This is actually just normal matter that we think should exist based on evidence but we can’t see? Any physicist bored and want to do a “explain it like I’m five?”
- nfc 6y agoYes, this is different from dark matter. This is baryonic "matter" that is predicted by our theories but that had not been previously detected. However the title is misleading, this is not the discovery of this matter even if the press release makes it look so. Previous detections of this matter had been discussed on HN before https://news.ycombinator.com/item?id=17953600 https://news.ycombinator.com/item?id=17953600 What this is is an advance on our understanding of this previously undetected matter. You can read more about it here https://www.aanda.org/articles/aa/full_html/2020/11/aa38521-20/aa38521-20.html https://www.aanda.org/articles/aa/full_html/2020/11/aa38521-..., this work has advanced our knowledge of the temperature and density of the cosmic filaments where this previously undetected matter is. I'm not an astrophysicist but I did my PhD about the stacking technique used in this paper (but applied to other problem). It was a long time ago though, I could be forgetting something important.
- mudita 6y agoCould you say more about what this stacking technique is? I got the impression that it's about combining different images by aligning and averaging them to get a better signal-to-noise-ratio, is this correct?
- AnHonestComment 6y agoMy understanding is like this: Imagine that you get one pixel for each hole in a chain link fence — the average color of light coming through that hole. If you take a second fence, that’s out of alignment with the first — you get better resolution because each hole in the original fence overlaps with several in the second fence, and you can examine their overlaps. The “size” of pixel of the two fences together is smaller than the size of the fence grating. A bunch of different overlaps, and some fancy statistics, lets you actually do that with space pictures. In essence, you reduce from the normal pixel size to the area of overlap between pixels. But if you only have the snapshot averages, you have to guess at what the original was — so statistical result.
- Cancan82 6y agoThis was a really great explanation. I love smart people who can dumb it down for me. Thank you. Very cool.
- SiempreViernes 6y agoOpen access <3
- Cancan82 6y agoThank you - this is really and the background here is helpful. Appreciate it very much.
- toxicFork 6y ago> Today, scientists at the Institut d'Astrophysique Spatiale (CNRS/Université Paris-Saclay) may have detected, for the first time, this hidden matter through an innovative statistical analysis of 20-year-old data. Their findings are published on November 6, 2020 in Astronomy & Astrophysics. Any links to the findings? Any search from me points of copies of the article rather than the source. Edit: https://www.aanda.org/articles/aa/abs/2020/11/aa38521-20/aa38521-20.html https://www.aanda.org/articles/aa/abs/2020/11/aa38521-20/aa3...
- deleted 6y ago[deleted]
- hi41 6y ago>> However, the signal emitted by this diffuse gas is so weak that in reality 40 to 50% of the baryons go undetected Since 40 to 50 percent of matter has been accounted for, does it mean that we no longer need dark matter to explain the missing matter?
- ttul 6y agoI believe they are just talking here about the missing baryonic matter; not dark matter. Dark matter remains a mystery.
- santoshalper 6y agoYeah, not only is a big chunk of gravity unaccounted for (potentially dark matter), but also a big chunk of actual matter could not be observed.
- fortranfourier 6y agoWhile a valid topic for a lecture or handful of folks, missing gravity or matter at distances greater than we’ll ever travel are like missing white kids’ pictures being put on milk cartons in the 80s: https://en.m.wikipedia.org/wiki/Missing-children_milk_carton https://en.m.wikipedia.org/wiki/Missing-children_milk_carton Part of the universe will remain unobservable, until we can bend space that far safely. What about making liquid nuclear fission better instead?
- monocasa 6y agoThinking about these concepts are what made systems like GPS possible. Shitting on pure research leaves you not knowing what you don't know to a much greater degree.
- fortranfourier 6y agoThe meaning of life is essential also. Feynman was curious. Where would we be if he obsessed over cosmology?
- LockAndLol 6y agoCosmic filament? What's that?
- dvh 6y agoGalaxies are not randomly distributed but they form lines or web instead of clumps.
- Eyght 6y agoHere is an image that shows how the cosmic web is usually illustrated: https://cdn.mos.cms.futurecdn.net/5mBKPZgrdD6ebdRtV8NEDZ-970-80.jpg.webp https://cdn.mos.cms.futurecdn.net/5mBKPZgrdD6ebdRtV8NEDZ-970...
- justadrunkJP 6y ago'Matter?' The obligatory dang-bait. Downvote me if you can. I subscribe to the Japanese philosophies.
- devenblake 6y agoIn accounting, when there are large discrepancies in their maths, they either hide the problem from their boss or re-do their work. In astrophysics they postulate about "hidden matter". However one must admit that, while astrophysicists have brought us memory foam, GPS, and satellite television, accountants have brought us only pain.
- andrewflnr 6y agoIt would be more accurate to think of astrophysicists as forensic accountants, figuring out the discrepancies someone else left in their work.
- jungletime 6y agoWell, scientist aren't sure yet. But they think it might be Joe's Ballots. They keep finding them in the darkest places.
- dschuetz 6y agoI don't like those click-baity headlines, especially when the article lacks substance and details.