Galaxies swarm and light bends under dark matter's sway

By Phil Plait | October 14, 2011 7:08 am

Before I do anything else, I simply have to present this insanely cool Hubble image of the galaxy cluster MACS J1206, which lies at the mind-numbing distance of 4.5 billion light years from Earth:

[Click to enclusternate, or grab the bigger 2564 x 2328 pixel version.]

Like I said, insanely cool. The cluster has thousands of galaxies in it, and a total mass of something like a quadrillion — that’s 1,000,000,000,000,000 — times the mass of our Sun!

The image was taken as part of a program called CLASH, for Cluster Lensing And Supernova survey with Hubble. A large group of astronomers from ten different countries are observing more than two dozen such distant clusters to look for many interesting things, including exploding stars (which help us gauge the expansion rate of the Universe), very distant galaxies (to help us understand the early Universe), and to look for dark matter.

Dark matter is stuff that doesn’t emit light, but has mass. Careful observations over the years have ruled out pretty much every form of normal matter we can think of, from simple hydrogen clouds to black holes. Whatever this stuff is, it’s weird, not matter as we know it.

But we do know it’s there. Its gravity affects how spiral galaxies rotate, how clusters like MACS 1206 stay together, and can even bend light from more distant galaxies as it passes through. That last bit is the big deal here.

Take a look at the cluster again. See those bright, weirdly drawn-out smears, as if someone grabbed a galaxy at both ends and stretched? Those are galaxies on the other side of the cluster from us, farther away. As the light from those galaxies passes through the cluster on the way to Earth, it gets distorted by the gravity of the galaxies in the cluster, and so we see the shape distorted. This is called gravitational lensing, and by carefully mapping that distortion, the distribution and amount of dark matter in MACS 1206 can be determined!

And that’s the whole point.

Now take another look at the picture. See how so many of the galaxies appear to lie perpendicular to the galaxy center? That’s another effect of the dark matter distortion; the smearing is tangential to the direction to the cluster center. So a lot of those distorted galaxies aren’t just smeared out, they look like little arcs, centered on the cluster center. Again, by measuring this, we can figure out a lot about the dark matter in the cluster.

I also got a kick out of this wiggly galaxy off to the right of the cluster center. How weird is that thing? It appears to snake around those two galaxies I marked, and I have to wonder if they have enough gravity to actually distort the light from that more distant galaxy that much, or if it’s just a coincidence. I’m having a hard time thinking it’s anything but the gravitational influence of those two galaxies doing that, but I’ve never seen anything like it! The astronomers published a paper about the program, but didn’t mention that squirmy guy in particular.

Also, if you look at the embiggened picture of the cluster, you’ll see it dotted with tiny red galaxies (I’ve cropped out a section here and marked three of them; many more can be found). I’m really wondering about those. Are they smaller cluster members, galaxies with so much dust that the starlight from them is reddened (the same way sunlight is redder at sunset), or are they big galaxies so far away they’re diminished in size through sheer distance, their light red shifted to that ruddy glow?

I don’t know. But the astronomers running CLASH will find out. Part of the program is to use the Very Large Telescope to get spectra of some of the galaxies in the survey, and I would bet a lot of money some of those little red dudes will be targeted. If they really are very far away, then they could prove very useful in understanding a lot about the early Universe.

I’m really impressed with this work so far, and in the ambitious nature of the survey. I literally gasped when I read that CLASH will get 524 orbits of Hubble to do this survey! That’s at least 300 hours of solid observing time, which is incredible. When I worked on Hubble, I was on some projects that got two orbits, and we were happy to get them! So 524 is an astonishing amount, and indicates pretty clearly that the folks in charge of giving astronomers time on Hubble think very highly of this project.

Given how much data they’ll be getting, I expect we’ll learn a lot about the mid- to very distant Universe in this survey, including how galaxies behave when they’re young, how the invisible fingers of dark matter shape normal matter, and even how the Universe itself is expanding on large scales. All of that, and much more, by taking a telescope, putting it up above our atmosphere, and letting it stare at one target after another for a long, long time.

That, plus the human ability to make sense of nature — which is what science is. That goes a long way, too.

Image credit: Credit: NASA, ESA, M. Postman (STScI) and the CLASH Survey Team


Related posts:

- Opening the lid on Pandora’s Cluster
- Astronomers have found when and how the cosmic fog was lifted
- Dark matter is alive and well, thankyouverymuch
- Found: 90% of the distant Universe
- Fermi may have spotted dark matter

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (47)

  1. Pete Jackson

    Great picture Phil! There is so much amazing stuff in it that one could look at it for hours!

    “See how so many of the galaxies appear to lie perpendicular to the galaxy center? ”

    Did you mean to say: “See how many of the galaxies are elongated perpendicular to the line joining them to the center of the cluster”?

    That squiggly galaxy looks like it is suffering from bad chromatic aberration, with the red light separated out to the right. Of course that isn’t really the case, unless the dark matter, not Hubble, is causing the chromatic aberration in some way. Weird.

  2. That’s an Space Eel! We need to prepare our fleet!!!

  3. Tony DeBlasio

    4.5 Billion light years!
    That light from the cluster left when the Earth was born.

    Amazing picture Phil.

  4. Beau Kemp

    Forgive my ignorance, but which object is MACS J1206? Is it basically the whole picture or the bright glob at the center?

  5. Ian

    Hi Phil,
    actually, individual galaxies can have very significant effects on the arc positions and shape–if you’re very close to the critical density, it doesn’t take a lot to bump you one way or the other. For an example, check out the arcs of CL0024+1654…
    Ian

  6. Trebuchet

    Aren’t you glad Sean O’Keefe didn’t get to carry through with dumping Hubble into the sea like he wanted? I am!

  7. PSP

    Yet another reason for funding the JWST. Since the Hubble has been (arguably) the most inspiring NASA effort of the past quarter century (oh, and fondness for Spirit and Opportunity remains high), we need to continue our robotic, grand scientific missions to probe the Universe at the greatest depths possible.

  8. IANAP

    IANAP, but how did they rule out black-holes in this case? I squirm whenever I hear “dark matter”.

  9. Endyo

    I also enjoy the squirmy galaxy. Gravitational lensing itself just sort of blows my mind. The idea that something I can’t see is distorting light with massive amounts of gravity on that scale is beyond what I can truly envision. Bending all that light… just wild stuff. I can see why they’re getting so many Hubble orbits for this though. It’s thoroughly exciting.

  10. VinceRN

    Seems weird they didn’t mention the space eel, especially if it is caused by the effects they are studying. It’s the first thing that jumps out of the image, and if your guess is right it’s the most dramatic example of gravitational lensing I’ve ever seen (not that I’ve seen near as much as you or the guys on this project).

    I wonder if there is some other explanation for it that led them to exclude it? Is it possible it could be some kind of artifact, or something else?

    As PSP above says, yet another reason the fund JWST.

  11. Ron1

    One the most primal of human desires is curiosity to see what’s around the bend, and this image offers quite a number of (gravitational) bends around which I’m really, really curious to see. So curious, in fact, that I’m ready and willing to beg that you Americans launch and provide on-going funding to the James Webb.

    Personally, I feel so strongly that James Webb is THE most important space mission going forward that I’d ask you guys and your government to consider opening up funding to the nations and individuals of the world. Let us help.

    Cheers

    ps. Phil, you’ve done absolutely spectacular work populizing astronomy over the last couple of days and it’s been a total joy reading the interactions of the newbies and the pros. This is BIG science, big reality that you are making available to all readers, regardless of their knowledge level. Well done.

  12. noen

    It’s all wibbly wobbly, timey wimey… stuff.

  13. Jon

    One question. How can we tell that it’s the cluster bending light, and not a black hole between us and that area of the sky distorting the light coming to us to look like that?

  14. Roger

    This just goes to show that Hubble is still very important to our learning about the universe and like having more than 1 ground based telescope, leave Hubble up there as another tool with the JWST to continue the endeavor to see stuff that inspires aw in us all on this blog.

  15. I work with the CLASH team (although I am not a member, I support them) and wanted to address the question of what those red dots were. According to Dan Coe (an actual team member), two of the three dots (the top one and the bottom one in Phil’s cutout) are mirror images of the same galaxy. There is a third mirror image of that galaxy just outside the FOV of the image from the press release. There isn’t an identified mirror to the middle dot.

    They are red because they are likely early-type galaxies at z~1.8 as opposed to z > 7 and high-z galaxies are bluer in these IR images.

    Hope this helps.

  16. Beau Kemp

    I’ll ask this again, maybe everyone just missed it.
    Forgive my ignorance, but which object is MACS J1206? Is it basically the whole picture or the bright glob at the center?

  17. @Beau Kemp The entire cluster is called MACS 1206, with a center of mass near the brightest galaxy of the image. All galaxies in the image are members of the cluster.

    One way to get a rough idea of the center of mass is to look at the orientation of all the arcs, they tend to make a big circle around the center of mass.

  18. Beau Kemp

    Thank you for the reply Tony, very helpful. FYI I love Deep Astronomy!

    I feel like a lot of times when astronomy pics are annotated by folks that look at them all the time, they forget that there are folks like me looking/reading. I need a little more “hand holding” for some things. I don’t know how many times I’ve looked at APOD or some other picture and been dumbfounded as to what the caption was actually referring to in the picture.

  19. Beau Kemp

    Like IANAP, the term “Dark Matter” also makes me squirm. I just don’t feel right about it. Not that I understand the math behind it or anything, but I just feel like that at some point in the future we will look back on dark matter and laugh. As this picture seems to indicate, dark matter adds to the overall gravity of the cluster and aids in gravitational lensing.
    Maybe scientists are wrong about how massive objects bend spacetime, or that space itself is “lumpy” and those lumps attribute to the dark matter phenomenon.

  20. Ron1

    @16 Beau Kemp and @17 Tony Darnell

    Gentlemen, it’s conversations like yours that make this blog such a joy. Great question and reply.

    @19. Beau Kemp, Dark Matter is, for me, simply a placeholder and, as a label, is no worse than some of the other silly terms physicists (geek gods that they are) use.

    Cheers

  21. When I see these gravitational lensing effects I wonder if it’s possible to “straighten out” the image with a bit of number crunching and see what it would look like without the distortion? A comparison between the two would then be even more dramatic, I reckon.

  22. L.Walker

    I dub you, Sir Squiggles of Bacon!
    Awesome photo – it’s so exciting! ^^

  23. The Hitch Hiker’s Guide to the Galaxy is a wholly remarkable book. The introduction begins like this:

    “Space,” it says, “is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.

  24. When I worked on Hubble, I was on some projects that got two orbits, and we were happy to get them!

    Is this our cue to start an astronomers’ version of the Four Yorkshiremen sketch?

    Two Hubble orbits? Bah! When I started doing astronomy, we had to wait until the end of the Milton Berle show before people would let us borrow their radios to build a VLA. And we liked it!

    Of course, my grandma could tell you a thing or two. You kids have it so easy, with your transparent universe and everything.

  25. Torbjorn Larsson, OM

    - Dark matter is a prediction of standard cosmology, so it is in no way an empty “place holder” or something totally mysterious.

    - We know it has mass and that it doesn’t interact much or at all with EM, which is why it is called “dark matter”, and all sorts of ordinary matter (inclusively black holes) have been invalidated as making the same predictions at some time or other.

    This is standard procedure. “Atoms” were “a placeholder” for ~ 2000 years (from natural philosophy), a predictive hypothesis for ~ 200 years (from chemistry), an accepted hypothesis for ~ 100 years (from Einstein predicting brownian motion), and earliest visualized as highs and lows in AFM images or as blinking ions in traps for ~ 10 years or so.

    We know more of DM/DE than chemists knew of atoms at the time they first realized it should be a feature of nature. So why do you expect to laugh at DM (or DE) when you don’t laugh at atoms any longer?

    I would say that if someone is skeptical at this stage, it isn’t based in an understanding of science and how it makes progress. All alternative theories have now fallen (we can model galaxies with DM!), and that means it is highly unlikely to be anything else than a done deal.

  26. Torbjorn Larsson, OM

    Oops. I meant to say that “We know it behaves as cold particles and …”.

  27. Cole A

    This is such a farce, the universe is only six thousand years old.

  28. yellow

    apparently it’s caused by some kind of mega-forces…

  29. Peter B

    Cole A @ #27 says: “This is such a farce, the universe is only six thousand years old.”

    If it is, then God created it in such a way that it looks much older.

    Are you happy to worship such a deceptive God?

    To put it another way, the reason astronomers talk of a universe that’s 13.7 billion years old is because they’ve gone where the evidence has led them. Remember there are plenty of Christian astronomers who have no problem with a universe that old.

  30. david

    “[W]e can model galaxies with DM!”

    OK, but I want someone to figure out why the DM generally seems to arrange itself so that MOND’s non-DM predictions work. When that happens, I think most of the skeptics will become believers. I know that if I was a DM cosmologist, I’d be losing sleep constantly over how the “baryonic tail” can be wagging the “DM dog”.

  31. Ron1

    @25. Torbjorn Larsson, OM Said: “Dark matter is a prediction of standard cosmology, so it is in no way an empty “place holder” or something totally mysterious. ”

    …………………….

    ??? I admit I’m scratching my head as to how you came to this conclusion. If you’re referring to my @20 comment, I was referring to the name, not dark matter itself.

    Cheers

  32. lisarenee3505

    I’m sorry Phil, but you are taking some pretty big liberties by claiming that “…we do know it’s [Dark Matter] there.” In fact, we don’t. Dark Matter is nothing more than a hypothesis, a stop-gap to plug the holes in Einstein’s theories, to explain the observational evidence that Einstein can’t. Kind of like how religion seeks to posit explanations of the otherwise unexplained by offering wild-eyed speculation and calling it “gospel.”. It is entirely possible – and in fact Occam’s Razor dictates that it is likely – that our understanding of physics is simply deeply flawed. What we need is a cadre, indeed an entire generation, of scientists who are willing to accept and embrace the idea that Einstein may have been wrong about Relativity. Not entirely, catastrophically wrong, but incorrect enough that it warrants admitting that while he may have been on the right track, he missed the real mark of truth by several degrees. Cosmologists and physicists are so entrapped by the ideas of Einstein that it has become anathema to suggest that perhaps we don’t understand the universe as well as we like to think we do. It is human nature to fear the unexplained, and to seek easy, pat answer for those phenomena. Scientists seem to be just as guilty as theists of clinging to the popularly accepted answers to the big questions, regardless of the evidence that suggests that their answers are incorrect. They seek to plug the holes with wild speculation that “feels good”, but simply does not fit the observational conclusions. As the popular hero of modern rational thought, Dr. Carl Sagan, once said “The critical issue is the quality of the purported evidence, rigorously and skeptically scrutinized, not what sounds plausible.”

  33. Kees Bijker

    I have been “stealing” hubble pictures for my computer for years, sorry guys but they are better than NSFW images!
    I have therefore quite some other gravitational lens pictures from H and I can safely say that in all of them are signs of the artifacts we are talking about here.

    The “red dudes” are in all of them but maybe less so than in this particular image which is outstanding on many fronts.

    The “space eel” is not immediately observed but with imagination you can understand the principle. If in the other images you would increase the compacting of the image towards the central section of the lens, you can see that some of the distorted galaxies would start to look like space eels as well. I think therefore that this eel is not the result of those 2 galaxies at either side of it alone but an accumulation of both that, and the lens effect. Just because this lens is so strong it compacts everything in a thin line and the orginal shape is lost to our eyes.

    The orientation perpendicular to the radiant of the lens is also present in all the other ones. I think that they all started out as round or near round galaxies which are orientated in random. The lens just pulls the light inward and squashes them in a circular fashion around itself.

    You might see the pictures yourself if you go to hubble site or the archives and find the following ones ( I hope the names are still the same as some are from hubbles early years)

    hs-2003-01-a
    hs-2006-23-a

    most were there in small and full format but I am not sure what they have left there today.

    I am sure that you guys can find even more pictures with the same effects, I just scanned my folders and found these 2 best ones to talk about.

    With regards to trolls…….I thought we didn’t talk to them here, so why the responses to the religious flavoured comments?

  34. … dark matter bends your mind, but not mine, ef dark matter, it is mine!

    Mind over dark matter! I see what it is doing, but then We already knew.

  35. DrFlimmer

    @ #30 david

    Well, four years ago I thought MOND was a good idea, too. However, MOND has one severe problem. Although you can explain many phenomena with it, different phenomena require different parameters within MOND making it inconsistent.
    And the worst thing for MOND is the Bullet Cluster, where the center of mass is clearly separated from the shine atomic stuff we are made of. This cannot explained by MOND, but by Dark Matter.

    @ #32 lisarenee3505

    Stating that Occam’s razor implies that our understanding of physics is deeply flawed, as you suggest, may seem an easy solution to avoid any meaningful discussions, however, it is not how science works. Sure, we should question our results from time to time, but not if they have been tested and tested and tested over and over again, and passed every single one with great success.
    If you think that General Relativity (GR) might “just be a theory”, you should check the evidence. GR works really fine. It is the best theory physics has ever achieved, along with Quantum Mechanics, of course. Your GPS wouldn’t work without it. The gravitational lens effect (which is the underlying effect mentioned in the article by Phil above) has been proven not only during solar eclipses, but also the predictions of the so-called Einstein rings turned out to be correct. Gravitational redshift (not to confuse with cosmological redshift, these are different things!) has been observed in several experiments. As a matter of fact, our atomic clocks become so precise that we have to take into account where we place them, because time runs differently on different heights above sea level. And there are many more.

    In short, before you question a (VERY) well tested theory, you must find evidence first that it might be incorrect! (And no, the one neutrino of recent doesn’t count. That claim is so extraordinary that it requires extraordinary evidence, i.e. more! Until then, one should stay quite skeptical about it.)

    Or in other words: What’s your theory that describes all these effects, and does so better than GR?

  36. Messier Tidy Upper

    Wow. That is one superluminous galaxy cluster image. :-)

    It almost looks like the galaxies there are moving – spiralling inwards towards the centre like a whilpool in a lake.

    @27. Cole A : “This is such a farce, the universe is only six thousand years old.”

    If you were doing a Poe there you need to try harder and add a ;-) emoticon at the end for clarity. If not, oh for pity’s sake, that’s just sad. Creationism has been debunked so many times in so many ways and is completely unsatisfactory as an explanation for the grand comos we observe all around in, well, images like this, the Hubble (Ultra-)Deep Fields and so many more.

    Six thousand years? We have ice cores and ancient cities older than that just here on Earth to say nothing of radiocarbon dating and so forth.

    So, please, Cole A, tell us whether you were joking or serious there and, if you were serious, what you think explains this “farcical” image if not modern science and what evidence you think suggests this glactic cluster is 6,000 years old or younger?

    Or as (#33.) Dr Flimmer put it above :

    In short, before you question a (VERY) well tested theory, you must find evidence first that it might be incorrect! (And no, the one neutrino of recent doesn’t count. That claim is so extraordinary that it requires extraordinary evidence, i.e. more! Until then, one should stay quite skeptical about it.) Or in other words: What’s your theory that describes all these effects, and does so better than GR?

    Or in your case, Cole A, what alternative theory do you offer explains MACS J1206 better than our modern cosmological understanding of the Big Bang and galaxy cluster formation and what evidence do you offer to support your ideas?

    Failure to answer that challenge reasonably would be, well, farcical really!

    @22. L.Walker : “I dub you, Sir Squiggles of Bacon!”

    Yes! :-)

    I second that name for that “wiggly galaxy off to the right of the cluster center” shown in the second photo here – it does, indeed, look just like rasher of bacon!

  37. david

    @ DrFlimmer

    Yes, I agree that MOND as a general theory is bogus. As it’s only a phenomonological hack, that’s hardly unexpected. What is unexpected (and deeply troubling given the current state of DM) is that it manages to do so many things so well with basically one parameter. The phenomena that it predicts on the galactic scale are just too darn impressive. IMO, DM people desperately need to explain how all the complicated possible galactic behaviors that would seem to be allowed by DM don’t happen, and instead how all the DM arranges itself so that MOND appears to be correct at the galactic scale.

    In other words, while MOND is bogus, the behavior it predicts on the galactic scale is real. DM must be able to give those same predictions, otherwise it’s also bogus. The DM people don’t seem to appreciate this nearly enough.

  38. Ganzyman

    Very nice. It’s like a galactic hall of mirrors. It certainly does appear that the ‘ghost’ image of that streaky bacon galaxy is being distorted again by those two smaller galaxies between us and the ghost image. Even the smaller galaxy two thirds of the way up the sbg appears to be distorting it too.

  39. @Kees Bijker: With regards to trolls…….I thought we didn’t talk to them here, so why the responses to the religious flavoured comments?

    Just because somebody else is rude doesn’t mean we have to be! ;-)

    I’m not sure whether Cole A is a troll or a Poe. Personally, I don’t think it hurts to calmly respond with facts & logic instead of leaving nonsense comments unanswered. I’m not getting upset or flaming anybody just putting in my view on what was said. Oh & I responded because I wanted to. I’m not saying others have to. Maybe you’re right & it is a bad idea. But maybe it’ll make the troll or some by-standers think anew and maybe its a good tool for keeping the mind somewhat sharp? Heck some of us [Mea culpa] just like discussing and even (politely) arguing things.

  40. Ron1

    @39 MTU

    Face it, you’re a good person, helpful and with good intentions. However, feeding the troll distracts the thread and often results in a foundation for thread hijacking. You know this ’cause you’re a Bad Astronomy ‘old fart’, like me.

    The Poe be damned, they’re worse than the pun.

    Cheers and good night.

  41. JohnLittle

    Dark matter is not dark, it is either see through matter, or SO dense that it can effect the light of a galaxy passing around it, yet so small as to not block any light that would make it detectable. M y pet hypothosis is that what we are seeing is the gravity of neighboring universes bleeding over into our own. What do you think BA?

  42. John Hannan

    I have heard through documentaries of the Hubble Space Telescope that the radius of the universe at this time is 47 billion light years from the birth of the big bang due to the expansion of space-time. This would make the diameter about 94 billion light years across and the circumference about 148 billion light years around, provided the universe is shaped like a sphere.
    So the Hubble Space Telescope takes photos of photons and a photon travels at the speed of light which is approximately 186,282 miles per second or approximately 97,909,819,200 miles per year. This being said, these photons could only be traveling for 13.8 billion light years.
    My question is, especially with the expansion of space time which seems to moves everything farther apart from everything else (I would assume that this includes photons), if the universe was brought into existence 13.8 billion years ago and that distance has been increased by 3.4 times, to equal the radius of 47 billion light years. Wouldn’t that mean that the furthest we could see anything at this point would be 4.05 billion light years away (13.8 billion divided be 3.4).
    And secondly, if this adjustment for the space time factor is not a factor at all for some reason. How is it that the Hubble Space Telescope can see galaxies that are 47 billion light years away when the photons from these galaxies have only traveled a maximum of 13.8 billion light years? It would seem as though they would be coming up about 33.2 billion light years short.

  43. flip

    #33, Kees

    If they’re in every photo, how can you tell it’s an artifact and not a common feature of the universe?

    And if it’s just a problem with the lenses, then you’d think the scientists would have noticed and corrected for it by now.

  44. Ron1

    @42 John Hannan said, “I have heard through documentaries of the Hubble Space Telescope that the radius of the universe at this time is 47 billion light years from the birth of the big bang due to the expansion of space-time. This would make the diameter about 94 billion light years across and the circumference about 148 billion light years around, provided the universe is shaped like a sphere.”

    …………………………………….

    Keep in mind that the radius of 47 billion light years is merely that of our observeable universe, not the entire universe. Cool, huh?

  45. icemith

    OK. Where and when did this figure of 47bn light years come about. I thought the operative figure was 13.7bn lys. Though I did wonder aloud in a previous blog (like yesterday), about the true physical nature of the Universe, I am thankful that something just happened to turn up, but I would like some justification.

    Unlike the Mayan calendar, which happens to “run-out” soon, I can conceive of much larger figures than the extended maths which gives us these measurements. I don’t figure it as “wishful thinking”, just an extension of good old Euclidean geometry.

    @42 John Hannan ……..” 47 … 94 … 148 …”

    These figures are mentioned, among others, and I have a pet beef regarding the quoting of circumference as if it matters, when we are dealing essentially with straight line distances from objects that are so very far away. If one was going to put up a boundary fence – yeah, it might be pertinent!

    Along the same line I hiss at the usual “mind-blowing distance”, the ISS has travelled since launch, or the latest SpaceShuttle or Probe for that matter, breaking records and toting up the miles. I know it is promulgated by the Popular Press, but why can’t the NASA agencies, TV News and writers of Reports, understand the public can comprehend these distances without going to the largest possible figure which is meaningless in the context of a short report?

    PS. I exclude that “largest possible figure” remark from the question of using “miles/kilometers”, as world practice dictates, where most of us use Metric measurements, and I am grateful Phil does too now, mostly, and first, where he does give the alternative.

    (Ha ha, metric is more!!!!) Insert emoticon here! (I’ve run out of yellow ink).

    Ivan.

  46. dtmfdude

    I think what dark matter is is matter from other dimensions. Scientists believe that there are “multi-verses”, can’t explain why there is so much matter compared to anti-matter and and so little visible matter when there should be so much more.

    If we were to go off on a tangent, doesn’t that seem “possible” that what we are seeing are the effects of other dimensions and it’s galaxies on our own? Where is all the anti-matter we think should have destroyed “our” matter in our universe, maybe that’s what makes up dimension (2) Yin / Yang?

  47. Matt B.

    @ John Hannan #42

    “So the Hubble Space Telescope takes photos of photons and a photon travels at the speed of light which is approximately 186,282 miles per second or approximately 97,909,819,200 miles per year. This being said, these photons could only be traveling for 13.8 billion light years.
    My question is, especially with the expansion of space time which seems to moves everything farther apart from everything else (I would assume that this includes photons), if the universe was brought into existence 13.8 billion years ago and that distance has been increased by 3.4 times, to equal the radius of 47 billion light years. Wouldn’t that mean that the furthest we could see anything at this point would be 4.05 billion light years away (13.8 billion divided be 3.4).
    And secondly, if this adjustment for the space time factor is not a factor at all for some reason. How is it that the Hubble Space Telescope can see galaxies that are 47 billion light years away when the photons from these galaxies have only traveled a maximum of 13.8 billion light years? It would seem as though they would be coming up about 33.2 billion light years short.”

    You’re doing the math backward. Imagine you run at light speed from one end of a wide slinky to the other, which starts out compressed. As you run, the slinky is being stretched out, so that, by the time you reach the other end, the slinky is now 47 billion light-years long. (We’ll presume that no matter how stretched out the slinky gets, you won’t fall between the coils. Also, your speed is relative to the part of the slinky you’re running on.)

    But as it turns out, you ran for only 13.8 billion years, because parts of the slinky that are now a light-year long were always less than that when you were running on them. And since every part of the slinky was somewhat stretched by the time you got to it, the starting length of the slinky must have been less than 13.8 billion light-years.

    So in a sense, the 13.8-billion-year age of the photons is an average between the short distance the photons started with and the long distance that exists now.

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