A three-dimensional map of the Universe

July 28, 2020 • 1:45 pm

Well, I can’t say I fully understand what’s being shown here, except that it depicts the detectable galaxies in the Universe (some not seen because the Milky Way hides them).  Cosmos has an explanation that I put below the video. If you’re an astronomy buff, you’ll probably understand this, and I’m hoping the cosmology mavens in the crowd will explain in the comments what we’re seeing.

Here’s one video, and another is below:

An explanation from Cosmos:

Astrophysicists have created the largest and most complete 3D map of the Universe.

It includes measurements of more than two million galaxies and quasars covering 11 billion years of cosmic time and involved 20 years of watching the skies and subsequent analysis by an international collaboration of more than a hundred researchers.

It is based on the latest observations of the Sloan Digital Sky Survey (SDSS), titled the extended Baryon Oscillation Spectroscopic Survey (eBOSS). The results and data have been released in more than 20 scientific papers running to 500+ pages.

Prior to eBOSS, scientists only knew where objects such as galaxies and quasars were as viewed from Earth. The new survey provides the distance to each object, allowing them to build a 3D model.

And that adds significantly to our understanding of the expansion of the Universe.

“We know both the ancient history of the Universe and its recent expansion history fairly well, but there’s a troublesome gap in the middle 11 billion years,” says Kyle Dawson, from the University of Utah, US.

“For five years, we have worked to fill in that gap, and we are using that information to provide some of the most substantial advances in cosmology in the last decade.”

The map has been published as a still image and as a 3D animation (below). A close look at the image reveals the filaments and voids that define the structure in the Universe, the researchers say, starting from when it was only about 300,000 years old.

h/t: Barry

47 thoughts on “A three-dimensional map of the Universe

    1. Ditto.

      “It includes measurements […] covering 11 billion years of cosmic time and involved 20 years of watching the skies […]”: doesn’t that make it 4D?

      1. For each galaxy they have its position on the sky (RA/Dec, pretty similar to latitude and longitude), plus its distance away, which is then equivalent to the time in the past at which we are seeing that galaxy. Since the last two are equivalent, it’s really only a 3-dimensional map.

          1. From the LCDM model we can tell, I think, how the universe will develop in coarse graining. The problem – which seems to be the new frontier (except for the tension in the expansion rate estimates) – is to grok galaxies, stars and their development.

  1. A timely thought

    I saw a bumper sticker about 3 hours ago that said:

    “The Big Bang was neither!”

    Amusing, perhaps. A Big Bang sticker on a … whatever it was … Ford neo-pickup-SUV monstrosity.

    With apologies to Don Henley.

  2. I remember seeing this data a few years ago in an interactive map. So this must be an update.

  3. ‘Once Upon A Time there was nothing and then there was a bloody Big Bang’. It’s late in the night here but is there anyone else out there who worries The Big Bang – for all its explanatory power – is the creation myth in long pants?

    1. “ … is there anyone else out there who worries The Big Bang – for all its explanatory power – is the creation myth in long pants?“

      … well, yes, I’m sure there are – not me – but I’m not worried about it – as there is nothing that can be done about it. Unless there is something that can be done about it, in which case, I am also not worried about it….

      … which makes this sounds like a case of the wrong question – if anyone is worried.

      1. For this reason, when I was young, I was confident the steady state theory was the right one. And then Penzias and Wilson discovered the Cosmic Microwave Background.

        1. This comment isn’t meant to sound aggressive – I’m just emphasizing a point, just for the record:

          The Big Bang, Cosmic Microwave Background, nor the steady state theory are or ever were any sort of creation _myth_. Phlogiston is not nor was it ever a myth.

          1. Didn’t take it as aggressive. Just saying that the steady state theory was more attractive to me, because of my atheism, than the big bang theory. But, unlike faithists, we can accept evidence that what we wish were true can be wrong.

              1. I was speaking for myself, not for all atheists. I found no beginning and no end more consistent with atheism. No need for a creator, or an end time. A beginning, like “Let there be light…” seemed religious to me. But it is a fact, so I accepted it. Although it still bothers me a bit, quantum fluctuation theory notwithstanding.

              2. Well it may make you feel better to know there was no beginning because time came into existence without the Big Bang.

              3. True, I suppose. The continuous creation of matter assumed by the steady state theory could be conceived as God’s continuous creative involvement in the universe.

              4. Sorry, I misinterpreted your comment, Diana. Yes, time without a Genesis type beginning was a big part of the appeal of the steady state model, for me at least.

              5. “Why would steady state be more acceptable to atheists than the Big Bang?”

                The irony here is that if the BOSS paper listing Weinberg’s selection bias as explaining the value of the vacuum energy, the larger multiverse it describes is a frustrated steady state. Lots (infinities) of local universe hot big bangs though – and if space is flat there is no energetic difference in any of them.

                “I thought the big bang started time according to Hartle and Hawking.”

                I *think* that inflation prevents HH tunneling from having happened, the energy in the inflation field is too low and the geometry of space is too nice to have started in a singularity. (I.e. you can’t derive a general relativity singularity.) But maybe the experts have other ideas.

              6. Also, I forgot the “< 5 % of comments" rule. :-/ So I shouldn't have responded as much.

              7. I’ve had a couple questions about all this, but one is the beginning of time and space. From the standpoint of eternal inflation in a multiverse, isn’t it evident that time and space did not begin with our Big Bang, 13.8 bya? There has to be continual time and space into which new universes continually form.

              8. The answer I e heard to that is the multiverse may have existed forever And who knows what kinds of time and space laws are in other universes.

              9. Mark,

                “From the standpoint of eternal inflation in a multiverse, isn’t it evident that time and space did not begin with our Big Bang, 13.8 bya? There has to be continual time and space into which new universes continually form.”

                From what I understand the Big Bang model simply dissolves into nonsense at some tiny fraction of a second prior to the actual Bang, so it doesn’t have any explanatory power further back than that. Which means that we don’t have any idea what anything was like prior to that time, or point or whatever.

                According to the Big Bang theory our space-time did not exist prior to the Big Bang. Whatever it is that our space-time expanded into, we simply don’t have any well verified hypotheses to describe it, and we don’t even really know if it is a sensible question.

                Intuitively it does make sense to suppose that there could be some larger, higher level, universe of which ours is but a part, but human intuition often fails, particularly at these scales. There are plenty of hypotheses/theories about such larger universes but they all suffer a verification problem. As best we can tell now we can’t observe anything outside of our universe so any theories about a larger scale universe can only be verified if they entail a unique feature in our own universe. And even then that would be pretty slim verification.

              10. “..Whatever it is that our space-time expanded into..”

                appeared above and it seems important to note that there is no need whatsoever for there to be something like that.

                This is analogous in a way to objects in geometry (‘manifolds’, to get overly technical) are always humanly pictured in most of our minds as sitting inside our picture of ordinary 3-dimensional space, like a beachball or an inner tube. But that is unneeded although it presents a useful math concept. Very roughly it’s a theorem that any, say 5-dimensional manifold can be ‘fitted’ into 10-dimensional (often less) ordinary space (i.e. all the points, each a string of 10 numbers). And the 5 and 10 above are really meant to exemplify ‘into ordinary space of about DOUBLE the dimension of the manifold’.

                Back to physics, the 4-dimensional spacetimes of classical (non-quantum) physics (GR) are studied almost always with no specific stuffing of them (’embedding’ they say) into any 7 or 8 or 9 dimensional ordinary space.

              11. @Mark: “From what I understand the Big Bang model simply dissolves into nonsense at some tiny fraction of a second prior to the actual Bang, … Whatever it is that our space-time expanded into,”.

                That this does not work as cosmology since 40 years back is what I tried to convey in the comment with the video: “you can’t make the homogeneous and isotropic universe we see out of the original “big bang” recipe. ” The video explains all that.

                And I believe the notion of something else “that our space-time expanded into” is an even older, pre-relativity notion of the hot big bang as ‘an explosion’. Einstein’s equations are self consistent, without any need for pre-existing space, when they are used in so called FLRW simplest possible models of the universe they instead use a scale factor to expand space [ https://en.wikipedia.org/wiki/Scale_factor_(cosmology) ].

                But you may first go to the video if you are interested in how modern cosmology work out – I hearthily recommend it! An acceptable understanding of how cosmologists think about the scale factor and the universe expansion didn’t appear for me before I watched 10 or so hours of Susskind’s MOOCs on cosmology – Wikipedia isn’t wrong, it just isn’t sufficient for some beginners.

                @phoffman56: “Back to physics, the 4-dimensional spacetimes of classical (non-quantum) physics (GR) are studied almost always with no specific stuffing of them (’embedding’ they say) into any 7 or 8 or 9 dimensional ordinary space.”

                Exactly! I don’t think embeddings such as string theory makes much sense any longer except as math, and the rest – but also with 4D quantum field theory – I responded specifically on your other comments here.

                [I might add on dimensionality that Tegmark makes an interesting observation that only 3D space can have non-leaky bags for cells. But IIRC Weinberg on his not-entirely-proven suggestion why gravitons are spin-2 vectors, that is also the only dimensionality of space that works for having gravity. And it is needed to “top off” physics under relativity to obey Lorentz invariance (obeying causality and having interesting local particulate objects). Either or both of those are consistent with Weinberg’s multiverse theory.]

    2. Not really, no more.

      The recent discovery that space is on average flat over sufficiently vast distances means it is on average zero energy density.

      So if you worry about something before, it took no outside work between then and now – it is spontaneous and nothing of matter or energy is “created”. (And space, whatever it is, is simply expanded.)

      Also, you can’t make the homogeneous and isotropic universe we see out of the original “big bang” recipe. That, and other observations like BOSS here, has ushered in an inflationary “hot big bang” cosmology. There the hot big bang can be defined as happening after the Hubble parameter gets down towards low values as today – there are several definitions, so you may have to read carefully.

      I will try not to embed a video that is helpful, based on a script from a know astrophysicist. It is short, and expand on the initial part at the end for clarity, so you may want to watch all of it. (It is silent on mechanisms, which saves time.)

      1. … and I failed to prevent embedding somehow, despite following what seemed like professional instructions. Sorry about that.

    3. General comment related to this and others:

      Forget about time for the moment. The universe, in the sense ‘all there is’, perhaps is a meaningful notion, but would include time as part of it, so it simply would exist, period, not ‘come into existence’, since the latter would involve another sense of time, not a part of it.

      This picture, which I don’t understand, has only to do with the visible universe, not ‘all there is’ certainly. Whether 2-dimensional(after all it’s a picture on a 2-dimensional page); or 3-dim. (just space which may simply be something which emerges from quantum field theory; or 4 dim. (including time, similarly emerging but QFT seems to need time in its very definition??); surely really depends on being clear what you’re talking about. So I’m not much help there.

      “Big bang” was originated by Fred Hoyle as a derisive term. He had partly originated the Steady State theory, but cosmic microwaves and expansion killed that. In any case, what is observed as that big bang ‘originated’ something like 280,000 (IIRC) years after the backwards-in-time theoretical shrinkage of the visible universe to a point, so it seems to have little to do with so-called ‘moment of creation’.

      “Creation myth in long pants” is just cutesy ignorance verbiage. A myth is something for which there is no evidence whatsoever. There is enormous evidence for what’s called CMB and expansion above. Whether scientists in the far future end up theoretically describing it quite differently than they do now will always be a part of scientific thought, even at that future time if it ever happens.

        1. It is and it isn’t.

          Time and space are not UNIQUE is the big first lesson from Einstein (even though many prefer to erroneously say they don’t EXIST). But there is a big difference between time-like curves and spacelike curves (or just lines in Special versus General relativity).

          1. It may be helpful to note that all we see can currently in principle be explained by low energy quantum field theory. This is Wilczek’s Core Theory [ http://www.preposterousuniverse.com/blog/2015/09/29/core-theory-t-shirts/ ], and it works for gravity [ http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory ]. And of course it helps that space is cosmologically (large scale) flat. Seems to me space curvature is the classical approximation to Feynman’s path integrals in gravity analogous to how field lines are in other quantum field theories.

            I’m hip with having space and time set by Noether’s theorem in Weinberg’s multiverse. Habitable universes may have values of fundamental parameters set accordingly, and having homogeneity and isotropy as a needed basis. Then you get conservation of properties simultaneously with getting the same laws as you move about inside your universe. Dunno what would be the rat or the rope in that, since gravity and inflation is necessary global fields. I can imagine that the universal speed limit (which is set by mass less gravitons in that picture) may vary. So what would Feynman’s path integrals say on that!? Hawking would have a “field” day.

            1. Speaking of Frank Wilczek, I am very enthusiastic about his fairly recent popular level book “A Beautiful Question”. Learning from that book at least a bit about his Core Theory is easier for non-physicists like me than anywhere else. With his supervisor Gross and another guy Politzer, they got a Nobel about 2000 for the work in mid ’70s, getting a quantum field theory to work for quarks etc. with the idea of asymptotic freedom–lots of others, e.g. Weinberg, Gell-Mann, had contributed beforehand.

              Wilczek had been a mathematics undergrad at UChicago just earlier (when I was there briefly I think, but he’s 10 years younger). Then he did his physics Ph.D. at Harvard. I feel just a bit personally connected also because a friend who was my math/physics classmate at Toronto as undergrads became Dean of Science at MIT, Bob Birgeneau. And as I understand it, he recruited Wilczek away from the Institute for Advanced Study to MIT, where he still is. (Bob became chancellor at Berkeley and does high temperature super conductivity kind of things.)

              Us old farts like to reminisce, sorry.

              Anyway, and you mentioned Emmy Noether, known mostly as probably the deepest, most productive female mathematician ever. But there’s more. And it’s connected to that Wilczek book above:
              To quote top of page 280:
              “And here we can display a precious gem. It is, I think, the single MOST PROFOUND RESULT IN ALL OF PHYSICS” (my caps)

              He then describes what physicists call simply Noether’s Theorem, connecting conserved quantities to symmetries (e.g. energy conservation comes from time translation symmetry, momentum from space translation, angular momentum from rotational invariance.) Many mathematicians seem to be unaware of how she did such wonderful work in physics (after Einstein and Hilbert asked her a question IIRC), while being well aware of all she did in algebra. Hitler drove her out of Europe with many other Jewish scientists, and she died in U.S. much too young.

              1. Thanks for the book tip, as well as the anecdote, much appreciated!

                For what its’ worth, here is Wilczek in his latest [?] exploit:

                “Even coherent gravitational waves produce graviton noise, but — as Dyson also found — it’s far too small to ever measure. This is because the jitter created as the detector absorbs gravitons is “exquisitely balanced” with the jitter created when it emits gravitons, said Wilczek, who had hoped that their calculation would lead to a bigger noise for coherent states. “It was a little disappointing,” he said.

                Undeterred, Parikh, Wilczek and Zahariade examined several other types of gravitational waves that Dyson did not consider. They found that one quantum state in particular, called a squeezed state, produces a much more pronounced graviton noise. In fact, Parikh, Wilczek and Zahariade found that the noise increases exponentially the more the gravitons are squeezed.

                Their theoretical exploration suggested — against prevailing wisdom — that graviton noise is in principle observable. Moreover, detecting this noise would tell physicists about the exotic sources that might create squeezed gravitational waves.”

                [ https://www.quantamagazine.org/gravitons-revealed-in-the-noise-of-gravitational-waves-20200723/ ]

                If we can see gravitons that would be huge! (Also, we would learn more about sources of gravitational waves.)

                It would be consistent with Wilczek’s theory, and it is also what they used in the work.

                Yes, Noether seems to have worked in the context of basic science – despite that she ‘was not supposed to’ – which is unusual for a mathematician. Einstein needed it for developing general relativity, I think, but that would not necessarily differ from math in general. But conservation laws and symmetries have been extracted and tested many times over, so that is physics when you apply it.

              2. Maybe humans will someday collect gravitational wave evidence from BEFORE the 380,000 (not my misremembered 280,000) years age of the cosmic microwave background, from before which ‘usual’ particles, even photons, can never be detected.

                Those are not related to this Wilczek, etc. work, I think?

    4. Personally I have no interest at all in the question of “..acceptable to atheists..” relating to scientific theories of any kind. The world is as it is, and we’re finding many things about it by science and only ever by science, but construed quite generally as discussed a few days ago.

      It seems to me that theologians have never had any idea, and surely never will have, about their god(s) as existing within time or not, just plain clueless IMHO on this and therefore even on the meaning of “creation of everything except the bloody creator herself or himself or itself”.

      1. The very idea of “nothing” when all we see looking back is something is an extraordinary notion without extraordinary evidence and also never quantified.

        My thinking is that it is the evolved capability to arrive at a notion of “object permanence” in babies that is the theological basis. They simply think in terms of objects and so agents, never in terms of dynamical processes. It really is “the universe, ELIF” to them.

  4. Thanks, the universe is much appreciated!

    Part of this I have said before, but now I have reason to put my entire initial reaction up:

    Being an integrative cosmological summary based on the baryonic acoustic oscillations and the cosmic microwave background to establish flatness it reinforce the standard model nicely.

    The structure data in the survey strongly fit dark matter evolving according to general relativity. The flatness of space is now 10^-4 – yielding a universe volume at least 100 million times larger than the observable – which is just an order of magnitude from the detection limit.

    Dark energy can be detected at 8 sigma based on accepting flatness, it is constant and yields a current expansion rate at H0 = 68.20 +/- 0,81 km s^-1 Mpc^-1 which likely means no physics (< 72 km s^-1 Mpc^-1 at nearly 3 sigma) and is consistent with simplest anthropic finetuning which they point out as possible and substantially strengthened explanation.

    "Nevertheless, the observed consistency with flat ΛCDM at the higher precision of this work points increasingly towards a pure cosmological constant solution, for example, as would be produced by a vacuum energy finetuned to have a small value. This fine-tuning represents a theoretical difficulty without any agreed-upon resolution and one that may not be resolvable through fundamental physics considerations alone (Weinberg 1989; Brax & Valageas 2019). This difficulty has been substantially sharpened by the observations presented here."

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