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Deepest Optical Image Of The Universe To Date

Posted by michael on from the asa-eight-million dept.

fenimor writes "The deepest optical view of the universe, obtained by Hubble Space Telescope, may turn out to be some of the earliest star-forming galaxies. The telescope has looked 95 percent of the way back to the beginning of time, to glimpse whether the hottest stars in these early galaxies may have provided enough radiation to 'cool' the universe after the big bang."

24 comments

  1. Still ditching Hubble? by Anonymous Coward · · Score: 0

    Even with stuff like this happening, are they still planning to ditch the Hubble?

  2. A question by T.Hobbes · · Score: 5, Insightful
    I was thinking about these photos, and came upon was seems to me to be a paradox. OK, so the Hubble takes this ultra-deep image of a point in space. This is said to be an image of the universe X billion years ago, and Y billion years after the big bang. All well and good.

    Now, so far as I know, intersteller distances are measured by the light year; Alpha Centuri is ~4 light years away, etc.

    I extrapolate from this that this ultra-deep and ultra-old image of the universe is both the _oldest_ and the _most distant_ image yet taken.

    The problem is this: You can point the hubble in any direction, and get an equally old image. Further, if you take a deep enough image, you can (theoretically) take an image of the Big Bang itself (or X million years after it, whatever).

    The paradox to me, is that this means the Big Bang can be conceptualized as a the outer edge of a sphere that surrounds us. You can, with the telescope, image in any direction in all three dimensions, and your limit wrt distance in any of those directions is the big bang. So the big bang is the edge.

    Now, this seems absurd to me, so I obviously got something wrong somewhere. Does anyone know what I got wrong?

    1. Re:A question by zrail · · Score: 5, Informative

      Technically, the furthest you can look back is about 300,000 years after the big bang, because thats approximately the point in time when the universe cooled down enough to become transparent. Before that, the universe basically consisted of a really hot soup of plasma.

      Try this page for some background information on cosmology and cosmic background radiation.

    2. Re:A question by Bootsy+Collins · · Score: 5, Informative

      Now, so far as I know, intersteller distances are measured by the light year; Alpha Centuri is ~4 light years away, etc.

      Well, actually, parsecs (and kiloparsecs and megaparsecs) are what tend to be used, for mainly traditional reasons. But it's a straightforward unit conversion.

      The problem is this: You can point the hubble in any direction, and get an equally old image. Further, if you take a deep enough image, you can (theoretically) take an image of the Big Bang itself (or X million years after it, whatever).

      In practical fact, you can't see back to the Big Bang, for a number of reasons. The first is that until a few hundred thousand years after the putative Big Bang, the Universe was opaque to radiation. Photons were simply too unlikely to pass much of any distance through the Universe without scattering off a charged particle of some sort. After that point, the Universe became transparent to photons. Consequently, that's as far back as you can see -- with photons, anyway. But you're right that you can see this change of state in the Universe (the so-called "surface of last scattering") in any direction you look, and in fact that's what astrophysicists are looking at when they map the cosmic microwave background radiation.

      The other thing that prevents you from seeing all the way back to the Big Bang is that as the Universe expands, light is redshifted (basically, its wavelengths are stretched out with the expansion). That's why we have to look in the infrared band for these distant galaxies, and that's why the light we observe from the surface of last scattering is in the microwave band. Light emitted at times closer and closer to the putative Big Bang is redshifted by larger and larger degrees, approaching infinite redshifting at the Big Bang itself (when the scale factor of the Universe, describing the expansion of space relative to today, is 0). So even if the surface of last scattering wasn't there, there'd be a practical limit to just how far back one could see, based on just how low-energy (long-wavelength) of photons one could detect and interpret.

      The paradox to me, is that this means the Big Bang can be conceptualized as a the outer edge of a sphere that surrounds us. You can, with the telescope, image in any direction in all three dimensions, and your limit wrt distance in any of those directions is the big bang. So the big bang is the edge.

      The Big Bang occurred everywhere. It occurred where you're sitting, where I'm sitting, and where Zaphod is sitting.

      Imagine some event -- say, the change of state that I described above, referred to as "decoupling", when the Universe became effectively transparent to photons, where before that it was opaque. This happened basically everywhere at once -- as the Universe expanded, densities and temperatures dropped until the scattering probabilities fell low enough. This happened everywhere, including right where you and I are now. But the photons that were around here then are long-gone now. They've been flying off in different directions since then. Similarly, the photons that were 10 light years away aren't around us either: the time they've had to fly, times the speed of light, is a long way from here. If you think about it, the photons you're going to see are ones that started out on a shell that's centered on us, with a radius equal to the distance light could travel in the time since decoupling (it's a little more complicated than that because of the expansion, but that's the basic idea). At any later time, from 1 second to 1 billion years later, that shell will be larger.

      So that's why we see a given time in the history of the Universe as a shell around us. It's not because these things (like the surface of last scattering, or the Big Bang itself) really are shells, but simply because that's all we can see. The photons that started at points interior to that shell aren't anywhere near us now; they've had enough time to propagate further than the distance between us and their starting points. The photons that started at points outside that shell haven't had enough time to reach us yet.

      Hope this clears things up some . . .

    3. Re:A question by NonSequor · · Score: 2, Insightful

      The universe isn't neccessarily Euclidean. There are all sorts of funky ways it can loop back on itself.

      --
      My only political goal is to see to it that no political party achieves its goals.
    4. Re:A question by tm2b · · Score: 1
      The problem is this: You can point the hubble in any direction, and get an equally old image. Further, if you take a deep enough image, you can (theoretically) take an image of the Big Bang itself (or X million years after it, whatever).
      Nope, we can only see back 14-15 Billion years. What's interesting is that our "horizon" is limited because the universe is expanding uniformly. IE, space is appearing between us and Alpha Centauri as much (per unit distance) as it is appearing between us and other galaxies.

      What this means is that there's a point out there beyond which we will never see because its distance is increasing from us (not moving: that would violate relativity) at "faster" than the speed of light. This horizon is "shrinking," too - there are stars that were within our horizon in the past that no longer are, because there's more space between us now than there used to be.

      That horizon is at 14-15 Billion years, where the Universe is thought to be about 156 Billion years wide.

      The clearest discussion I found of this on-line is here: http://www.pbs.org/wgbh/nova/universe/howbig.html
      --
      "It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny
    5. Re:A question by Jormundgandr · · Score: 1

      Or 13.7 billion if you follow the latest corrections to Big Bang theory.

      --
      -sig removed for tax purposes-
  3. a correction by T.Hobbes · · Score: 1
    Where I said "The paradox to me, is that this means the Big Bang can be conceptualized as a the outer edge of a sphere that surrounds us. You can, with the telescope, image in any direction in all three dimensions, and your limit wrt distance in any of those directions is the big bang. So the big bang is the edge."

    I should have just said "You can conceptualize the universe as a sphere, with the Earth (or Hubble) as the center, and the Big Bang as the outer edge. No matter what direction you travel in, the most distant point is always the big bang."

    (This stuff confuses me)

    1. Re:a correction by TMB · · Score: 2, Informative

      There's a big difference between those two statements! The first one is quite correct (well, except for issues relating to the opacity of the early universe - if you did it with a neutrino telescope or gravitational radiation telescope, you could theoretically see back to almost the Big Bang). The second isn't - if you travel, you're going forward in time, whereas when you look at light from far away, you are seeing back in time.

      [TMB]

  4. I think you're right by Anonymous Coward · · Score: 2, Interesting

    The Big Bang obviously no longer exists at a single point in space. The residual image is at the outermost edge of the universe. What's the paradox?

  5. Aha. by Anonymous Coward · · Score: 0

    No, the Earth isn't really the center of the universe (medieval theories notwithstanding). But regardless, the most distant point in any direction will be the residual image of the Big Bang. (Because the Earth isn't at the center, that most distant point might be farther in one direction than in another.)

    I believe that, in terms of overall distance, though, you may as well consider the Earth to be at the center. (A few hundred-thousand light years offset isn't significant compared to many billions of light years.)

    1. Re:Aha. by escher · · Score: 4, Informative

      (Because the Earth isn't at the center, that most distant point might be farther in one direction than in another.)

      A better way to look at it is that every point can be considered the center of the universe. No matter where you are, the egdes of the "big bang sphere border" will be equidistant from your location.

  6. Seems correct, but no paradox .. by RedLaggedTeut · · Score: 5, Informative

    I think what you say is basically correct:
    If you look out as far is possible, which should be either the point in time where the universal "balloon" expanded at the speed of light, or maybe so far that the Hubble constant times the distance is the speed of light, then you get to see the big bang.

    Most of it is called the cosmic microwave background.

    There are two reasons why there isn't as much of a paradox:
    One is that spacetime might look like this: Space is 3D, but consider that it as 2D, then the universe would look like a balloon that gets inflated: every point on the balloon seems to be at the center of the explosion called big bang.

    The second reason is that it gets harder to see the big bang itself, because Einsteins relativity theory predicts really big shifts in wavelength for stuff that moves away near the speed of light - so any electromagnetic waves and light from the big bang would be far below infrared and low in energy. And incrementally so as you get to look closer to the big bang.

    --
    I'm still trying to figure out what people mean by 'social skills' here.
  7. 95% Really? by redog · · Score: 3, Funny

    "The telescope has looked 95 percent of the way back to the beginning of time,""

    Then it can tell me where I put those keys a couple days ago?

    Right?

    Please!

  8. So did anybody see by Marxist+Hacker+42 · · Score: 2, Funny

    The Big Bang Burger Barn? (obRef, Restaurant at the End of the Universe).

    --
    SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
  9. Actually, you are correct... by j_cavera · · Score: 5, Interesting

    This is not a paradox, rather just a way of looking at it that is different than what you are used to. The universe at the beginning of time, existed as a point (more or less) that expanded (somehow) into what we see today. As you look out into the universe, you also look back in time. The farther back you go, the smaller the universe was.

    By logic, if you could look all the way back to the big bang itself, you would see a point of light. And this is where your percieved paradox occurs. But this is actually the correct way of thinking about it, because time = distance. So where does that point lie? Everywhere, at a distance of 15 billion (give or take) light-years from us! So no matter where you look, you see a "part of that point" from 15 billion years ago.

    OK, this is an oversimplification as the universe was opaque for some time after the big bang, but you get the idea. Here's a potentially useful (though not perfectly accurate) analogy. Go inside a large spherical room with white walls. Put a bright light bulb at the center (big-bang). The walls are evenly illuminated because no matter which way you look, your line of sight intersects with some of the rays of the bulb, that seem to come to you from all around you.

    In fact, if you had a good enough detector, you could determine the shape of the bulb's filament by irregularities in the light from the walls. This is what the cosmic background explorer (COBE) missions are about.

    BTW, yes IAAP (I am a physicist).

    --
    #include "humorous_pop_culture_reference.h"
    1. Re:Actually, you are correct... by Guignol · · Score: 2, Interesting

      Hi,
      Sorry for the offtopicc, but all seems quiet and since YAAP and seem to know about the stuff I thought I'd just ask :)

      I am wondering if, today, we have some real "expectations" about the universe course from big bang (if big bang there was) to now and if yes, if we have commonly believed aswers (or prefered models about this) about the following assumptions that I make myself when trying to imagine the whole picture:

      - The universe is roughly a 4D sphere, and we belong to its boundary (or the universe *is* this boundary however one wants to view it)
      - At big bang event, this sphere radius was nearing zero and is since then expanding
      - This expansion implies an expansion of the surface which is the "texture of the universe", it's not (not only) the universe elements that fly appart (matter and light) but there is more and more space to be moving around.
      - There can be thus combined expansions:
      we can see matter moving away for whichever reason (forces, initial velocity etc.), but "space" itself while expanding, can move its population around with its expansion. (this latter movement being not subject to physical limitations like speed of light I suppose)
      - However, since I think that we believe that matter is being moved by this space expansion, and since we can still see "things" around us, I suppose this expansion rate is well under lightspeed (at least today, I wonder if we think this speed has been varying since the beginning)

      So, if all of this makes sense, my idea, and main question is this:
      at one point, we could have had an universe large and old enough to see stars and galaxies forming, yet (maybe) small enough to be fully explorable in a fraction of the time given from them until now.
      (I mean that, at this time we could have started exploring the universe in a straight line and come back (since it's spherical) before (or at most until) today (travelling at lightspeed).
      Then, a star (or something brighter, like a group of galaxies) would send its light in a spherical way fast enough to reach the "Universe equator" and start contracting back to until reaching the oposite pole of the universe and from there expand back again (even self interfering on a surface which would be defined as a matter of the lifetime of said light source and the expansion speed of the universe).
      Is that correct ? if not why not ?
      If yes, couldn't be today witnessing such things like mirror effects ?
      I'm asking this because if indeed we believe having covered 95% of the whole universe and if those conditions are plausible, then maybe we can see "mirror effects". The mirror effects would be of different natures according to several considerations:
      We should see the mirror effect of lightsources that "were coming from some point at some time, and which appear from the oposite direction in the exact same (inversed) way at a precise later time. Those Timings and directions being influenced by our observer's relative position to an original source and "where was 'its' equator" ('its' because we all have one) then and now.
      Now, I am realy wondering how we could even tell an original from its mirror...
      and there are also two kind of incoming lights which must be somthing specal to see: expanding light versus contracting light. I suspect seeing contracting light coming to us (if we are on the other side of this particular source equator at the time we received its light) the we must be "feeling" it comes from another direction.
      Just like mass can deflect light, exept this would be then be very exessive bending.
      Now, if we are able to guess today's size of the universe, its expansion speed during the time and age of galaxies, couldn't a 95% map of the universe give us some definite clues about its very shape ?
      That is, if we witness those mirror effects, or if we should but don't, or if in some region the mirrors are "too late" or "too scatered" etc. couldn't we infere that; for instance, the universe is in fact, say,

    2. Re:Actually, you are correct... by div_B · · Score: 1

      We should see the mirror effect of lightsources that "were coming from some point at some time, and which appear from the oposite direction in the exact same (inversed) way at a precise later time. Those Timings and directions being influenced by our observer's relative position to an original source and "where was 'its' equator" ('its' because we all have one) then and now.

      I think there is active research into this, ie, we should be able to see an image of our own galaxy out there somewhere, and it is being looked for. There was an article about it in a New Scientist/Scientific American/??? a few years ago, sorry that's all info I have. :)

    3. Re:Actually, you are correct... by j_cavera · · Score: 1

      OK, that's a lot to process but here goes: > The universe is roughly a 4D sphere... Actually from the COBE experiments and the large scale structure of the universe (galactic superclusters and all), the universe is very close to flat, hyperspatially speaking. As of yet, no one knows how this came to be or what it means. > ...sphere radius was nearing zero and is since then expanding True enough, if you substitute "shape" for "sphere". It's almost meaningless to discuss the shape of the singularity at the big bang. It is, after all, a (hyperdimensional) point with no shape. The shape since the big bang is unknown, but probably some hyperspheric section. > This expansion implies an expansion of the surface... > ...we can see matter moving away for whichever reason... Both statements are substantially true. It is even possible for different regions of space to expand at different rates (though they don't seem to be doing that now). It is also possible for the expansion to occur faster than the speed of light. As you said, it's not really matter that's moving. Current thought is that the universe underwent a period of FTL expansion shortly after the big bang. This is (appropriately enough) called the "inflationary period". After a few hundred thousand or so years of this, the expansion rate slowed to more modest levels. BUT - the expansion rate is now increasing! No one is sure why... > (light mirror thoughts) You are actually correct in your assessment. It is possible that, at some time in the past and in some part of the universe, the hyperradius of space time was small enough for a beam of light to "catch itself". There is a very good reason that this didn't happen. Unfortunately, were not real sure of that reason. Current thought is that gravity, vaccum fluctuations, dark matter or just plain stuff got in the way and caused the light to scatter. Another thought is that the shape of the early universe was sufficiently "bizarre" to prevent such closed paths from occuring. That said, there is one place where this effect does occur. Around a black hole, there is a hypothetical surface called the light sphere, around which light can be captured and made to orbit the black hole forever. As the gravity of a black hole twists space-time into a nasty mess (technical term), this is physically identical to your smaller space time idea. > ... two kind of incoming lights which must be somthing specal to see: expanding light versus contracting light. Not sure what you mean by this. It is possible for an optical wavefront to converge and diverge. If this is what you mean, then we already have good examples. A black hole (or other massive object) can form a gravitational lens. If it is directly in front of a star, and appropriately aligned with earth, there may be multiple images of the star, or even a ring of light around the massive object. These are caused by the optical wavefronts bending around the object. In a sense, expanding and contracting the image of the star behind it. And yes, such pictures are really neat to see. > ...couldn't a 95% map of the universe give us some definite clues about its very shape? That's the plan! This is why the COBE satellites were launched and why the Hubble is still kept so busy. As I mentioned though, the universe still looks flat. Anyway, your ideas are good. Sorry for the delay in getting back to you and feel free to send e-mail to me at: j_cavera@yaDONTEVENTHINKOFSPAMMINGhoo.com

      --
      #include "humorous_pop_culture_reference.h"
  10. We were part of the big bang too. by geoswan · · Score: 2, Insightful
    The matter that makes up the Earth, you and I, the sun, our Galaxy, was all part of the explosion we call the Big Bang. So you don't have to look far away, and deep into the past to see something that was once part of the Big Bang. Everything you look at, including the nose on your face, was once part of the Big Bang. So, the Big Bang is not the edge of the Universe.

    1. Re:We were part of the big bang too. by plog · · Score: 1

      what was, is

      and what is, won't be

      because you have seen it into being

    2. Re:We were part of the big bang too. by luna69 · · Score: 2, Interesting

      > The matter that makes up the Earth, you and I, the
      > sun, our Galaxy, was all part of the explosion we
      > call the Big Bang.

      Well, yes, and no. "The matter" was indeed formed during the big bang (well, shortly after it, during nucleosynthesis). But only Hydrogen, Helium and a little Lithium. The rest of the actual atoms you and I are made of were formed in stellar cores as a result of fusion (for elements lighter than and including Iron) or in stellar supernovae (for all elements heavier than Iron).

      Pretty cool to look at a gold ring on your finger and contemplate its origin in an exploding star.

      See: http://en.wikipedia.org/wiki/Big_bang_nucleosynthe sis

      and

      --
      No gods, no demons, and no masters. Secular Humanism!
  11. Really Hot Soup of Plasma by Anonymous Coward · · Score: 0

    I had a bowl of that the other day: not as good as Moroccan Chicken, say, but WAY better than Cream of Asparagus!