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Laniakea Supercluster
- cdelsolar 3y agoWhy are there so many stars and galaxies?
- q845712 3y agoif it helps, that's just the stars and galaxies we're capable of observing. There's probably more :)
- qup 3y agoIt's fun that we can't say for sure. I wonder how long before we can
- PartiallyTyped 3y agoThe other side to this is that given enough time, some civilisation will be oblivious to the rest of the universe. Their visible universe will just be their own galaxy.
- alx 3y agoand what could they deduce from the void they have in front of them?
- PartiallyTyped 3y agoProbably nothing. The problem is that at such timescales, the CMB will have shifted sooooooooo much that there’s nothing they will be able to deduce, all light has redshifted to absurd scales, and worst of all, everything will be so far away that light will never reach the galaxy.
- BitwiseFool 3y agoThat means they would have no way of discovering that the universe is expanding, right?
- PartiallyTyped 3y agoNB: Armchair """""physicist""""" If their physics is correct, they will figure it out. We did because we verified that expansion is accelerating even though our physics are incomplete. Until the late 90s, physicists accepted a cosmological constant of 0, which meant no acceleration. Turns out that that was wrong. It may be possible that they figure it out via Quantum Mechanics because it seems that acceleration of the universe is related to the energy density of a vacuum / empty space. The problem is that they won't be able to empirically verify that I think.
- r2_pilot 3y agoThe physical continuing expansion of the universe eventually causes any photon to be so far redshifted as to be unobservable, so it actually goes the opposite way. One day long from now, an alien civilization might look out into their night sky and only see their galaxy, and be completely unable to tell the previous history of the universe from observing the sky.
- Sanzig 3y agoThere's also a possibility that a sizeable fraction of all stars exist in the intergalactic medium [1], having been ejected from the galaxies where they formed due to galactic collisions or encounters with their original galaxy's supermassive black hole. A civilization evolving around one of these stars in the far future would be totally unaware of the universe outside their own solar system due to cosmic expansion. [1] https://en.wikipedia.org/wiki/Intergalactic_star https://en.wikipedia.org/wiki/Intergalactic_star
- asimovfan 3y agoI agree, things couldn't be fun if we actually knew what they were
- ceejayoz 3y agoThere are probably hundreds of possible answers to that, depending on which aspect you're interested in, ranging from "God" to "gravity" to "42" to "because" to "I dunno".
- deleted 3y ago[deleted]
- igleria 3y agoat risk of being too tautologic: Because for us this is "so many". Because of that we try to compare the scale of the universe with the amount of sand on earth etc etc. At least for me, that type of information does not give me a "better" idea of the problem at hand other than "duuuuuuuuude what".
- kirykl 3y agosee Feynman on "why" https://www.youtube.com/watch?v=36GT2zI8lVA https://www.youtube.com/watch?v=36GT2zI8lVA
- TechBro8615 3y agoProbably for the same reason there are not zero.
- Koshkin 3y agoProbably because there may be an upper limit on the size of an individual celestial object (and thus on how many particles it can consist of) - for it to be anything other than a black hole, anyway. In the future, the Universe will entirely consist of black holes, whose number will be much smaller.
- dredmorbius 3y agoI don't know what limits there are on the size of galaxies, though I suspect it share some characteristics with that of stars. For star formation, however, the tension is between the outward flow of matter and simple photonic pressure on interstellar gas, competing against the inward pull of gravity. That is: stars form as large "dust" clouds (mostly hydrogen atoms, obviously), collapse. Once those reach a critical mass, fusion initiates within the stellar core. The rate of fusion is moderated by the pull of gravity, such that larger stars, fighting more inward mass, burn far hotter (and faster, and live comparatively short lives: a few tens of millions of years for the very largest, as compared with ~10 billion for the Sun, and potentially trillions for brown dwarfs which eke out their fuel slowly). In a curious bit of physical synchronicity, the energy density of the Sun's core (the part which is actively generating energy), in terms of watts/kg, is roughly equivalent to that of mammalian metabolism. It's just that there's a whole lot more mass to the Sun's core than there are mammals, and of course, we're comparing nuclear reactions with chemical ones (the Krebs Cycle). Back to stars: as they ignite, they start blowing the dust that's forming them away, and so limit their maximum growth potential. The least massive stars (brown dwarfs) are roughly 10x the mass of Jupiter, or about 1/100th the mass of our Sun, the most massive stars are roughly 100x the mass of the Sun, giving a total effective range of roughly 1:10,000. The upper bound, called the Eddington Mass Limit, is about 120 solar masses, and is based on total luminosity which translates to outward pressure exerted by the star against the stellar medium surrounding it: <https://en.wikipedia.org/wiki/Eddington_luminosity https://en.wikipedia.org/wiki/Eddington_luminosity> I don't know what the dynamics governing galaxy growth are, though a few ideas come to mind. Apparently the most massive galaxies are about 100x the size of the Milky Way (so we're at roughly similar ends of the scale for both stars and galaxies in that regard) in the Physics StackExchange post below. The discussion there does mention luminosity and pressure, though there's also some disagreement over just what constitutes a galaxy, and where to draw borders. <https://physics.stackexchange.com/questions/172953/what-is-the-limit-for-the-size-of-a-galaxy https://physics.stackexchange.com/questions/172953/what-is-t...>
- StackOverlord 3y agohttps://en.wikipedia.org/wiki/Dipole_repeller https://en.wikipedia.org/wiki/Dipole_repeller
- kibwen 3y agoThe next time you address a package to someone, err on the side of caution and append "Earth, Solar System, Local Interstellar Cloud, Local Bubble, Gould Belt, Orion Arm, Milky Way, Milky Way Subgroup, Local Group, Local Sheet, Virgo Supercluster, Laniakea Supercluster, KBC Void, Observable Universe, Universe", to help the package carrier disambiguate.
- deleted 3y ago[deleted]
- kunwon1 3y agoWe're going to run out of address space, time to migrate to zip code v6
- atonse 3y agoWill the 128 bits be enough to address all atoms in all universes?
- NoMoreNicksLeft 3y agoYes, in all 2 universes.
- stvltvs 3y agoLooks like we'll need to upgrade to 512-bit addresses to be on the safe side. https://www.wolframalpha.com/input?i=log2%2810%5E80%29 https://www.wolframalpha.com/input?i=log2%2810%5E80%29 https://www.thoughtco.com/number-of-atoms-in-the-universe-603795 https://www.thoughtco.com/number-of-atoms-in-the-universe-60...
- m3kw9 3y agoWe just need (universe)UPS coordinates.
- jamesgreenleaf 3y agoYou don't have to specify "Multiverse" on the end, because your package will be automatically delivered to all of them.
- FrustratedMonky 3y agoanybody have super high res pic of this?
- stronglikedan 3y agoIt's available right on that page (after clicking the preview): https://upload.wikimedia.org/wikipedia/commons/8/81/07-Laniakea_%28LofE07240%29.png https://upload.wikimedia.org/wikipedia/commons/8/81/07-Lania...
- escapecharacter 3y agoI do, but it is the same number of bytes as the entire universe
- pmlnr 3y agoThere's also a short video on this: https://www.youtube.com/watch?v=rENyyRwxpHo https://www.youtube.com/watch?v=rENyyRwxpHo Plus there's that scene from Stargate Universe: - Are those stars? - No, those are galaxies.
- ktm5j 3y agoSGU was by far my favorite Stargate and I'm forever sad that it only lasted two seasons
- deleted 3y ago[deleted]
- haunter 3y agoThis will sound stupid... but as we find out that the universe is bigger and bigger and there are more clusters, galaxies, stars, and planets then we have imagined before (Laniakea have 100,000–150,000 galaxies and the Milky Way _alone_ have 100–400 billion stars) so does that increase or lower the chance that there is _any_ kind of life outside there? Maybe not carbon-based life but any kind. Next question would be I guess that what is "life" Fascinating stuff nonetheless
- pfdietz 3y agoRealize that if the cosmological constant has the nonzero value that appears to be the case (in the lambda-CDM model), then only about 6% of the galaxies we see are still reachable. The rest will be carried away by accelerating expansion so quickly that a photon emitted from us right now (or any slower than light spaceship) will never reach them. Of course more stars increases the chance of life out there, but without a good handle on the chance of life arising around a random star, we cannot set any lower bound on the probability that life is out there on the stars we see.
- kibwen 3y agoA good and accessible video on this topic: https://www.youtube.com/watch?v=uzkD5SeuwzM https://www.youtube.com/watch?v=uzkD5SeuwzM
- taneq 3y agoSo it’s a fancy skybox. ;)
- dougmwne 3y agoOne that functions as the greatest physics experiment we could never run and has revealed countless laws of the cosmos, yes!
- johncessna 3y agoWild, I've def heard of some reasons how the Fermi paradox could be resolved, but I missed this explanation. A quick headline scan of the wiki article also doesn't mention it. [1] You'd think that 94% of the observable universe not being reachable would get more of a mention. Granted, we can still look for artifacts such as radio signals or something similar, but it does seem to cut out why a type 3 civ hasn't shown up at our door. [1] https://en.wikipedia.org/wiki/Fermi_paradox https://en.wikipedia.org/wiki/Fermi_paradox
- Steltek 3y agoFor the neverending stream of talk about VR this, metaverse that, and WebGPU there, there should really be a KISS 3D format for the web so we can view things like this properly. Like Markdown simple. No shaders or animation or anything like that. Default lighting only. It feels sad to look at a 2D image of the most 3D of all things.
- Tommstein 3y agoHow about VRML or its successor X3D? They support fanciness, but you don't have to use it any more than you have to use every random feature in Markdown.
- Koshkin 3y agoCame here to learn about some new HPC supercluster... Oh well.
- aktuel 3y agoyeah this supercluster is pretty high performance it might even do some compute but it is definitely not new
- frinxor 3y agoFollowed some links around, and this was interesting https://en.wikipedia.org/wiki/Abell_3266 https://en.wikipedia.org/wiki/Abell_3266 ! "The Department of Physics at the University of Maryland, Baltimore County discovered that a large mass of gas is hurtling through the cluster at a speed of 750 km/s (466 miles/second). The mass is billions of solar masses, approximately 3 million light-years in diameter and is the largest of its kind discovered as of June 2006."
- NKosmatos 3y agoWe need Faster Than Light (FTL) travel otherwise we’re stuck here on Earth. I believe that there are other beings out there, but the vast distances prevent contact. If they haven’t discovered exotic means of travel like wormholes, hyperspace, warp drives, or something else, then we’re doomed to remain separated :-( https://en.wikipedia.org/wiki/Faster-than-light https://en.wikipedia.org/wiki/Faster-than-light
- xwdv 3y agoWe’re not doomed and we don’t need to be separate. We just need to be patient. We must be willing to send generations of humans on thousand year journeys.
- dredmorbius 3y agoEven with generation ships, the expansion of the universe means that most of what we can now see we can never reach, even at lightspeed. Patience ... is not sufficient in this case. (It may still be all we have, and quite possibly more than we have.)
- antonvs 3y agoPhysics has all but ruled out faster than light travel for squishy beings like humans, or for that matter even sensitive electronics. The equations that allow for wormholes or Alcubierre drives don't mean it's possible for living beings or working electronics to actually successfully make a trip through such extreme and unlikely phenomena. It's a bit like saying you'll slingshot around a black hole close to its event horizon to gain enormous speed: you could do that, but tidal forces will rip you apart in the process. Except wormholes and other such spacetime anomalies are worse.
- cthalupa 3y agoTidal forces are highly dependent on the mass of the black hole. The more massive, the less tidal forces you have to contend with. The bigger problem is finding such a black hole that doesn't have a very unfriendly to life and electronics accretion disk. I've seen some arguments that alcubierre drives could allow for safe transportation with materials science advancements that we believe to be possible. Safe for the people traveling, at any rate. Not so safe for your destination and whatever else is in a large cone in front of your ship. I've not seen any convincing arguments that would allow for anyone to safely traverse a worm hole, however.
- graycat 3y agoStart with an analogy: We've never seen a car before but find one, learn how to drive it, and are amazed, and ask "How does this amazing thing work?". We study the rubber in the tires, the disk brakes, the air conditioning, the universal joints, differential, the transmission, the pistons. Then we see the box that has the computer for controlling the fuel injection and ignition and start to take it apart to see how it works when one of us says: "Stop. In broad terms, I can tell you how it works: It does what it needs to do so that the car can work. But by now we have gone so deep into how this car works that it is time to ask What is the purpose of this car?" The universe as it seems from current astronomy, ..., is one huge and intricate construction. Sorry, but tough to believe that all of this has no purpose. Ah, two possibilities: (1) We really are the center of the universe and the only life. There is a lot less to the universe than what seems from current astronomy. In particular, objects we can never reach due to the speed of light limit are just fake, something like a painted screen. (2) We have not found it yet, but there is a way to violate the speed of light. The whole universe is ours for the taking once we see how to exceed the speed of light. There is a game: For the laws of physics, how long will it take for life to develop to understand these laws and, in particular, how to exceed the speed of light? For either of (1) or (2), maybe we should start a new subject, super cosmology, that assumes that the universe has a purpose. We look for that purpose and, for each discovery we make, e.g., dark matter, quantum mechanics, black holes, quasars, gravitational waves, ..., ask what its role is in the purpose of the universe.