Universe has 2 trillion galaxies, astronomers say

Oct 14, 2016

By AFP in Paris

There are a dizzying two trillion galaxies in the universe, up to 20 times more than previously thought, astronomers reported on Thursday. The surprising finding, based on 3D modeling of images collected over 20 years by the Hubble Space Telescope, was published in the Astronomical Journal.

Scientists have puzzled over how many galaxies the cosmos harbors at least since US astronomer Edwin Hubble showed in 1924 that Andromeda, a neighboring galaxy, was not part of our own Milky Way. But even in the era of modern astronomy, getting an accurate tally has proven difficult.

To begin with, there is only part of the cosmos where light given off by distant objects has had time to reach Earth. The rest is effectively beyond our reach. And even within this “observable universe”, current technology only allows us to glimpse 10% of what is out there, according to the new findings.


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35 comments on “Universe has 2 trillion galaxies, astronomers say

  • 1
    Pinball1970 says:

    Two trillion 10 >12 or 10 >18?

    It still is a lot either way

    Does this mean that the estimates for the overall density are out?

    Does this in anyway account for any missing matter?

    If not, all that extra matter yet the universe is still expanding at an accelerated rate.

    I need Quatermass (I think that is the name) and Phil on this.



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  • @OP – To begin with, there is only part of the cosmos where light given off by distant objects has had time to reach Earth. The rest is effectively beyond our reach.

    This is “the observable universe” which the laws of physics and light speed, allow us to see.

    And even within this “observable universe”, current technology only allows us to glimpse 10% of what is out there, according to the new findings.

    Then there are the limitations of our present technology which only detect a percentage of this – some of it, only with the aid of gravitational lensing where there is assistance from a favourable line up of galaxies and stars.



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  • Mods, are you aware that the title of this article has changed since this was posted (see footnote at bottom of OP)? It’s now called “Universe has 2 trillion galaxies, astronomers say”, rather than “Universe has two trillion more galaxies than previously thought”.



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  • I am going to make a bold prediction (tongue in cheek).

    The number of galaxies will continue to increase as we refine our techniques. I’d not be surprised at all if, by the time I am an oldster (on my way) we are talking about twice as many galaxies as we currently can observe. And, the lurking variable, here, has to be our complete inability to reliably estimate all we don’t “see”.



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  • crookedshoes #8
    Oct 14, 2016 at 2:06 pm

    The number of galaxies will continue to increase as we refine our techniques.

    Well yes and no!

    If we are seeing as far back as 13 billion years, that does not leave a long way to go to the big-bang.

    Also, distant galaxies are receding from us, while the arrow of time moves forward, so the boundary of the observable universe keeps changing.

    Also, as the nature of galactic evolution is that galaxies merge, and large galaxies grow by sucking in and absorbing smaller galaxies, the actual number of galaxies will get smaller, as the mass consolidates into larger galaxies.

    http://spaceplace.nasa.gov/satellite-galaxies/en/



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  • 10
    Pinball1970 says:

    Ok good we got the big guns

    so to recap, this is not an issue of models being wrong? It is all about resolution of images?

    If we can see back 13 billion years (I presume in all directions?) is that not ALL the universe?

    Whats left?

    If my questions are seem naive and confused that is because I have little idea about what I am talking about.

    I have read a lot of books regarding points on this but I struggle with size and shape of the universe and how far back we can “see”

    2 trillion extra galaxies seems a lot to add, will this not alter things like the critical density? Expansion rate?



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  • Galaxies in the early universe were much smaller with fewer stars, they were also much more numerous. As time passed they bumped into each other and coalesced, becoming bigger galaxies but with more stars. (An incidental interesting question is how their core black holes and any dark matter interact. Do their black holes inevitably coalesce? I woud guess almost certainly, with spectacular results. A further question, is the suspected black hole heart of galaxies of studied, big near galaxies, in fact, caused first by collision and coalescing? Or were black holes needed to form those smaller virgin galaxies?)

    As we look out across the universe the further we look the longer ago we look, the smaller and more numerous the galaxies. These are less bright as seen by us now both because they are smaller and because their apparent brightness falls off with the square of the distance in the usual way. It has been very difficult to assess how many more and how much smaller when they were first formed.

    None of this is unexpected, its jut that careful and methodical study of the latest Hubble images has given us a more definitive estimate of the number of galaxies that were originally formed.

    Today, across the universe, there are not 2E12 galaxies but some lesser number. But as we look out a long way we can only see long ago. We simply presume that observers ten billion lightyears away see their local galaxies as big and many starred also.

    No extra matter has been detected in this way nor any net density difference when assessed at the biggest scales, just a greater homogeneity at lesser scales.

    E is for exponent and what you see on scientific calculators as a shorthand for n “times ten raised to the power” m, where n and m in our case are two and plus 12 respectively.

    The ASCII text shorthand 10^12 is of course ten raised to the power (plus) twelve.

    Sorry this is a bit basic but covers this pretty well and others may choose to refresh their school maths. Note its good for tiny numbers also. 2E-12, is two trillionths.

    https://www.mathsisfun.com/index-notation-powers.html



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  • Silly question?

    Is there a way of telling whether any of these galaxies are the same galaxy that has had its light bent many times and reflected back to us and are viewed at different stages of its time?



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  • Olgun #14
    Oct 15, 2016 at 7:27 am

    Is there a way of telling whether any of these galaxies are the same galaxy that has had its light bent many times and reflected back to us and are viewed at different stages of its time?

    When a double (or maybe a quadruple) image is produced by gravitational lensing, the images are close together and match each other’s properties. The large mass which is causing the lensing effect can also be found between the imaged object and the observing telescope.

    https://www.nasa.gov/content/goddard/hubble-hubble-seeing-double/#.WAIWZ_RHpVk

    In this new Hubble image two objects are clearly visible, shining brightly. When they were first discovered in 1979, they were thought to be separate objects — however, astronomers soon realized that these twins are a little too identical! They are close together, lie at the same distance from us, and have surprisingly similar properties. The reason they are so similar is not some bizarre coincidence; they are in fact the same object.

    These cosmic doppelgangers make up a double quasar known as QSO 0957+561, also known as the “Twin Quasar,” which lies just under 14 billion light-years from Earth. Quasars are the intensely powerful centers of distant galaxies. So, why are we seeing this quasar twice?

    Some 4 billion light-years from Earth — and directly in our line of sight — is the huge galaxy YGKOW G1. This galaxy was the first ever observed gravitational lens, an object with a mass so great that it can bend the light from objects lying behind it. This phenomenon not only allows us to see objects that would otherwise be too remote, in cases like this it also allows us to see them twice over.

    Along with the cluster of galaxies in which it resides, YGKOW G1 exerts an enormous gravitational force. This doesn’t just affect the galaxy’s shape, the stars that it forms, and the objects around it — it affects the very space it sits in, warping and bending the environment and producing bizarre effects, such as this quasar double image.

    The first detection of gravitational lensing meant more than just the discovery of an impressive optical illusion allowing telescopes like Hubble to effectively see behind an intervening galaxy. It was evidence for Einstein’s theory of general relativity. This theory had identified gravitational lensing as one of its only observable effects, but until the observation of these quasar “twins,” no such lensing had been observed since the idea was first mooted in 1936.



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  • Thanks Alan. But can the same effect sort of ounce around the universe and come at us from opposite direction and because of the extra distance travelled show us the same galaxy millions of years apart in time?



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  • Olgun, light is rather more “refracted” than reflected. Bending is the accurate term. The amounts of bending involved in the hundreds of gravitational lensing observations made to date are modest with small angles involved and very small relative differences in time delay. The “lensing” effect does not produce an image as such like a real lens. Any image survives only if the bending is slight. The dramatic bending you might get near the (tiny) event horizon of a black hole would destroy any coherent image so bending like a “reflection” would result in a pretty meaningless spray of light.



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  • Olgun #16
    Oct 15, 2016 at 7:58 am

    Thanks Alan. But can the same effect sort of ounce around the universe and come at us from opposite direction and because of the extra distance travelled show us the same galaxy millions of years apart in time?

    I don’t think that is at all likely:-
    first all, because this is a narrow angle lensing and not a mirror effect,
    and secondly light travelling “around” the outer limits of the universe, would head outside of the visible universe, and limited by light speed, would never have the time needed to come back.
    Light from out there, beyond the boundary of the visible universe, is too slow to reach us even on a one-way trip.



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  • I was thinking along the lines of bending Phil with lots of little bends resulting in the angle needed but wasn’t sure if energy or clarity was lost. In my mind, it would not need to reach the outer edge of the universe but would still have to travel a long long way like a tanker turning. Probably in the realms of science fiction rather than fact. Thanks again to both you and Alan.
    I think bounce (or ounce as I misspelled above) was the wrong word and not what I meant at all.



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  • Olgun,

    Clarity would be lost at each stage (and chaotically so) defeating any coherence well before 180 degree total bend could be achieved. The added time delay (and incidentally light intensity fall off) of much longer path lengths as Alan mentions will limit observation to much nearer fields of view anyway, rather defeating the intention of analysing the distant.



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  • Alan4, Phil, Olgun, pinball,

    I am so not versed in this type of discussion. I look through a microscope and am comfortable if my estimates are off by a bit but not by too much. Standard deviations, t tests, f tests, chi square analysis… etc… bears me “confidence intervals”… With this “updated number”, I do not know whether to be comfortable or confident because being off by a factor of X20 seems (to a microbiology guy) to be pretty far off. Is it? Is this an acceptable amount of error? Does it make the “old” numbers suspicious?



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  • crookedshoes #21
    Oct 15, 2016 at 4:14 pm

    With this “updated number”, I do not know whether to be comfortable or confident because being off by a factor of X20 seems (to a microbiology guy) to be pretty far off. Is it? Is this an acceptable amount of error? Does it make the “old” numbers suspicious?

    When we talk about images of small distant patches acquired by using gravitational lensing to see well beyond the normal range of our instruments, we are talking about estimates from very small sample areas using low resolution images.

    On top of this, because of light speed and light-year distances, the images of very distant galaxies, are as they were billions of years ago, when galaxies were smaller, less consolidated into larger ones, and more numerous.

    Does it make the “old” numbers suspicious?

    The improvements in the technology and methodology, have revealed much greater numbers and more details than previously believed – but that is true of the whole history of astronomy – and of science in general.



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  • Does it make the “old” numbers suspicious?

    Not really. We weren’t around to see the size of galaxies in our local neighbourhood then, when they would be more numerous and smaller. And though we can see back in time when they are far away we fail to see the smaller ones even more than we fail to see the big ones. Its like perspective diminution squared.

    Heaven knows how Father Ted would explain it to Dougal.

    https://www.youtube.com/watch?v=dS12p0Zqlt0



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  • Alan4, phil et al,
    I am used to the “science in general” progression of more and more detail (yielded by more and more techno breakthroughs)…. I am comfy with it. However, that comfort is typically tempered by the idea that our models are fundamentally sound and will always endure refinement.

    I am just confused by the seeming magnitude of the “new” data. And confounded because my “prediction” of more and more galaxies in the future turns out to be lukewarm. It’s puzzling. Is it like looking into a fractal and seeing increasing complexity with increasing magnification? Is it like that weird shit that starts to occur in the quantum world? Or, is it likely that we are only part the way there with our estimate of galaxy number?

    I mean the “plum pudding” model of the atom was “wrong” but it tempered the “update” and really paved the way for our current models. It just seems that being off by a factor of 20 indicates that we still could be off by another factor of 20 (or more). Please advise.



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  • crookedshoes #24
    Oct 15, 2016 at 5:43 pm

    It just seems that being off by a factor of 20 indicates that we still could be off by another factor of 20 (or more).

    We could easily be that wrong or more (as astronomers have been in the past), but that is just projected speculation on my part.
    There is still a huge percentage of the universe and of time, we have simply not observed, cannot observe with present technology, or cannot observe at all!

    All these guestimates are based on small samples of what we can see.

    After all, it’s not yet a hundred years since Hubble confirmed there were stars and other galaxies outside of the Milky Way!

    http://amazingspace.org/resources/explorations/groundup/lesson/scopes/mt_wilson/discovery.php

    In the early 1900s, astronomers were debating the makeup of spiral nebulae — cloudy, spiral-shaped objects found throughout the night sky. Were they gas clouds located within our Milky Way galaxy, or were they vast groups of stars located far beyond our galaxy?

    In 1923, Hubble found dozens of these variable stars in Andromeda, and determined their distance. He calculated that Andromeda must be at least 10 times farther away than the farthest stars in the Milky Way. The Andromeda nebula was really the Andromeda galaxy. This discovery implied that the other, even fainter, spirals were probably also galaxies even farther away.

    Hubble published his work in 1929 and changed forever our view of the universe. Astronomers no longer thought our galaxy was the entire universe. Now they knew that the universe was composed of many, many galaxies.



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  • Crooked

    I am just confused by the seeming magnitude of the “new” data

    But there wasn’t really any old data for the initial number of galaxies. There was/is a number for the mass of the universe and that hasn’t changed. I think people assumed we may have had a larger number of smaller galaxies at the time of galaxy formation, but given the the modest number of galactic collisions we see happening in our locality we might have estimated a rather low greater initial number. In fact it transpires that that there was probably a very large number of very small galaxies that collided and coalesced like mad until things settled down a bit.

    What they did was look at the number and percentage of progressively smaller galaxies in the mid field as far as they could reliably see and create a model for how galaxies appear to have clumped in relation to time, then projected back to the far field where they couldn’t see such details.

    The Guardian article is very misleading. The replacement headline is still wrong. There aren’t 2E12 galaxies any more. There are 1.5E11, though we,of course, seem to see more than that in the sky. This is far less significant than it was made to sound.



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  • Anyone care to speculate about the limits of what is observable? I’m positing that if you look progressively farther, you’ll see more galaxies come into view. What if there is no end to time space/time. Even though we trace everything back to a big bang, if it goes space/time forever, isn’t it a default formula for, dare I say it Hoyle’s steady state universe. Lastly, the big bang looks infinitely small to us, why isn’t it infinitely large to something else within it. An analogy is that it kind of reminds me of the funnel problem in Calculus. It has an apparent finite volume, but a lengthwise cross-section has an infinite surface area.



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  • savroD #27
    Oct 15, 2016 at 7:48 pm

    Anyone care to speculate about the limits of what is observable?

    The “observable (part of) the universe”,is the sphere around us where the distance in light-years is equal to, or less than the age of the universe since the big-bang. Any light from more distant objects has not yet had time to reach travelling at light-speed.

    Due to the limitations of our technology the areas and distances we can actually observe at present, is considerably smaller than this theoretical maximum.

    I’m positing that if you look progressively farther, you’ll see more galaxies come into view.

    That has been happening as the technology has improved, but we will not see any light from objects at a distance which requires the light to travel for longer than the age of the universe generated by the big-bang.

    What if there is no end to time space/time.

    There are various theories and speculations about this but the Universe has billions of years to run anyway. – long after our Sun fries the Earth and the Andromeda galaxy merges with the Milky Way.

    isn’t it a default formula for, dare I say it Hoyle’s steady state universe.

    There is solid evidence for the big-bang from the inflationary stage onwards. Hoyle’s theory was refuted, although stars do continue to form from primordial hydrogen, clumping under the force of gravity.

    Lastly, the big bang looks infinitely small to us, why isn’t it infinitely large to something else within it.

    The initial pre-Planck epoch, Grand unification epoch/ pre-inflation stages, of the big-bang are unknown at present.

    https://en.wikipedia.org/wiki/Chronology_of_the_universe



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  • very cool conversation. thanks for taking your time to share your knowledge. Dovras, your last post was what I call a “pot thought” or a “highdea”…. like in the movie Animal house when Donald Southerland’s character “potificates” about the universe. your post has me thinking and deeply in waters that i am out of my comfort zone in. Well done people!!!



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  • Melvin #30
    Oct 16, 2016 at 9:11 pm

    Does this mean I am trillions of trillions times less significant than I thought I was in September?

    Once-upon-a-time, the whole universe was viewed only a flat Earth populated by ego-centric humans, surrounded by celestial spheres inhabited above the clouds, by angels!

    Then the geocentrists re-wrote the story with the Sun as the centre of the universe and human egos took a small knock! – while “angels” were becoming homeless!

    Later, it was discovered that our Sun was a star, and there were numerous other stars in the galaxy which made up “our universe”.
    Not only that, but these other suns might have planets – even inhabited planets!!

    Then in the 1920s Edwin Hubble went and showed that our Milky Way galaxy was not the entire universe, but other galaxies also existed.

    As the telescopes and technologies improved, the size of the observed universe and the count of stars and galaxies just keeps going up, with the ego-centric theist claim that the trrrroooo god’s human worshippers are THE central feature of the Universe, diminishing, (along with planet Earth), to the status of a sub-microscopic percentage of a vast universe! –
    So small in relation to the overall mass of the galaxies, , that for the usual level of scientific measurements and functions of the whole, they would be a negligible trace of negligible consequence!



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  • When I worked for Buckminster Fuller in the late 1970s, he would sometimes tell a story about how small we are, as a creature on the Earth and in the Universe.

    It would be an interesting thing if people would relate the relative size (to human beings or the Earth) of what they write about, like in this article about vastness of the Universe, it does not say anything about the relative size of human beings to this vastness. Or perhaps a separate feature about the relationship we have with the world (Earth, Sky, Solar System, Milky Way, etc.) in a relative way, you know, scale and orders of magnitude. This conveys to the senses our place in the real world.

    I can repeat some of Fuller’s story, not verbatim…

    The Earth is approximately 8,000 miles in diameter. If the Earth were scaled exactly to 6 feet in diameter, standing in front of it, and touching it, its surface would appear as a perfectly polished sphere, you would not be able to feel the mountains and ocean depths, they would be too smooth to detect by touch, or even by sight. The Atmosphere would only be the thickness of a sheet of paper. Breath on the surface to leave the fog of your breath, that would equal the relative depth of the oceans.

    I could go on and on…



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  • I am not completely sure about my figures but; the combined science of all our observations with telescopes, visible, x-ray, gamma-ray, radio, microwave, gravity-wave, etc; only records information from about 20% of what is suspected to exist outside detectability. The James Webb telescope hopes to expand that another few percent, to a region currently undetectable but known to exist. The universe was opaque for hundreds of millions of years with no photons whatsoever, then the hundreds of millions of years after that time is red shifted so much rendering it undetectable and may always be undetectable. Who knows what wonders Science can come up with that I can not even imagine, to detect and record things that currently are outside detection.



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  • Sadly, Jay, Fuller was inaccurate, The earth is exactly ten thousand (old) kilometres from pole to equator. (The original definition of a metre.) Everest is getting on for ten thousand metres high, one thousandth of that distance.

    A sphere of 4 metres circumference (one metre from equator to pole or 4.13 feet diametre) would have Everest as a (nearly) one millimetre bump. The Himalayas would definitely feel scratchy on a four foot earth.



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  • Melvin #30
    Oct 16, 2016 at 9:11 pm

    Does this mean I am trillions of trillions times less significant than I thought I was in September?

    I can’t read your mind or interpret it from the zodiac, but I guess it could be so!

    However there are those who consider themselves to be an important feature, directing human activities from watching the stars of the Universe, despite a lack of any scientific knowledge of astronomy!!

    https://www.richarddawkins.net/2016/09/nasa-we-didnt-change-your-zodiac-sign-astrology-isnt-real/#li-comment-212874



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