by Ann » Sun Oct 20, 2024 6:07 am
Well, that's a nice surprise! A non-comet, non-aurora APOD! We haven't had many of them lately.
My first thought, when I just glimpsed the APOD, was, "Wow, that's a lot of fireflies in that thicket of branches!".
Note that even the real fireflies follow the "filaments" and avoid the "voids"!
The cosmic web itself is made up of filaments and voids:
The picture above was used in a ResearchGate paper and I was going to quote from it, but I'll refrain, because these guys did not grow up speaking English, and their attempt at using it as a second language in a scientific paper was just moderately successful. However, the point they are trying to make is interesting, because they claim that the pressure of cosmic voids may be a source of both dark matter and dark energy.
Like this, perhaps?
So the authors said that the voids are like bubbles with surface tension that keep growing in size, thus "pushing" on the Universe, making it grow larger. They also said that the universe is in fact dominated by its large voids, and that the effects are felt locally more than globally. I couldn't follow their reasoning, however, both because of their less than perfect grasp of English and my own very far from perfect grasp of the underlying scientific concepts. Note that I stole the longer image caption above from the authors. I tried to improve their grammar, but I don't know if I succeeded. I think I know what they are trying to say, however.
The publication source is
here, but you have to download the PDF yourself if you want to read it.
But clearly, when the universe was young, it was much denser than it is today and the voids must have been much smaller. Not only are the voids now larger, but as the universe expands, the voids are dominating larger and larger parts of the universe.
For some reason I am reminded of the murmurations of starlings, when starlings form huge clouds of hundreds of thousands or even millions of individuals that fly and dance together in amazing configurations. They even create filaments and voids sometimes.
Click to play embedded YouTube video.
Now we just have to figure out what makes fireflies imitate that structure of the universe.
Ann
Well, that's a nice surprise! A non-comet, non-aurora APOD! We haven't had many of them lately.
[img3="Dark Matter in a Simulated Universe. Illustration Credit & Copyright: Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH"]https://apod.nasa.gov/apod/image/2410/DarkMatter_KipacAmnh_960.jpg[/img3]
My first thought, when I just glimpsed the APOD, was, "Wow, that's a lot of fireflies in that thicket of branches!".
[img3="Fireflies Event at Norton Creek 2021. Image credit: I don't know, but the picture can be found here: https://dlia.org/event/fireflies-2021/"]https://dlia.org/wp-content/uploads/2019/01/fireflies-DSC_2613.jpg[/img3]
Note that even the real fireflies follow the "filaments" and avoid the "voids"!
The cosmic web itself is made up of filaments and voids:
[img3="The cosmic web is mostly occupied by vast voids: The bright regions are clusters and filaments of galaxies, dark regions are voids and blue dots are single galaxies inside the cosmic voids. Image credit: Either Ebrahim Yusofi or the cosmic web page in www.outerspacecentral.com."]https://www.researchgate.net/profile/Ebrahim-Yusofi/publication/354884627/figure/fig1/AS:1072905530126336@1632812020493/The-cosmic-web-is-mostly-occupied-by-vast-voids-The-bright-regions-are-clusters-and.png[/img3]
The picture above was used in a ResearchGate paper and I was going to quote from it, but I'll refrain, because these guys did not grow up speaking English, and their attempt at using it as a second language in a scientific paper was just moderately successful. However, the point they are trying to make is interesting, because they claim that the pressure of cosmic voids may be a source of both dark matter and dark energy.
Like this, perhaps?
[float=right][img3="A schematic image of a void-dominated cosmic fluid that is occupied by vast voids: Negative pressure or repulsive force (like a concave lens) of vast voids on galaxies in the walls acts as the positive pressure or attractive force on it like a convex lens at a local scale (yellow circle)."]https://www.researchgate.net/profile/Ebrahim-Yusofi/publication/354884627/figure/fig2/AS:1072905530122240@1632812020554/Schematic-of-void-dominated-cosmic-fluid-that-occupied-by-vast-voids-Negative-pressure.png[/img3][/float][attachment=0]Growing voids in the cosmic web Ebrahim Yusofi.png[/attachment]
[clear][/clear]
So the authors said that the voids are like bubbles with surface tension that keep growing in size, thus "pushing" on the Universe, making it grow larger. They also said that the universe is in fact dominated by its large voids, and that the effects are felt locally more than globally. I couldn't follow their reasoning, however, both because of their less than perfect grasp of English and my own very far from perfect grasp of the underlying scientific concepts. Note that I stole the longer image caption above from the authors. I tried to improve their grammar, but I don't know if I succeeded. I think I know what they are trying to say, however.
The publication source is [url=https://www.researchgate.net/figure/The-cosmic-web-is-mostly-occupied-by-vast-voids-The-bright-regions-are-clusters-and_fig1_354884627]here[/url], but you have to download the PDF yourself if you want to read it.
But clearly, when the universe was young, it was much denser than it is today and the voids must have been much smaller. Not only are the voids now larger, but as the universe expands, the voids are dominating larger and larger parts of the universe.
[img3="Our expanding and accelerating universe. Credit: NASA/Jet Propulsion Laboratory (JPL)"]https://d2pn8kiwq2w21t.cloudfront.net/images/infographicsuploadsinfographicsfull10824.width-1320.jpg[/img3]
For some reason I am reminded of the murmurations of starlings, when starlings form huge clouds of hundreds of thousands or even millions of individuals that fly and dance together in amazing configurations. They even create filaments and voids sometimes.
[youtube]https://www.youtube.com/watch?v=uV54oa0SyMc[/youtube]
Now we just have to figure out what makes fireflies imitate that structure of the universe.
[img3="A firefly in a void, with no pals around it. Credit: Ali Majdfar/Getty Images"]https://i.guim.co.uk/img/media/fc47bab11c9a5e023d3c0d3e84c7c87474d0aa6b/466_507_3000_2000/master/3000.jpg?width=465&dpr=1&s=none&crop=none[/img3]
Ann