How Can We See Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?

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Tue, Feb 6 - 1:50 pm EDT | 7 years ago by
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HubbleultradeepfieldThis is my second post in the Just Science Week Challenge.

This 2003 paper in Physical Review Letters puts a lower limit on the size of the universe at no smaller than 46.5 billion light years in radius. If the universe is geometrically flat, that is.

In this video I made on the Hubble Deep Field, I mentioned this number and was immediately inundated with questions and comments from people screaming that that number could not possibly be correct. How can the universe be that big if the fastest anything can travel is the speed of light? The universe simply CAN’T be larger than the distance light travels during age of the universe, right?

Wrong.

It is true that the universe is 13.5 billion years old, and it is also true that nothing can travel faster than the speed of light. But it does NOT follow that the size of the universe is simply the distance light traveled in 13.5 billion years. You can’t stop there. Why?

Because the universe is expanding, and has been for 13.5 billion years.

Remember yesterday’s post? Everything in the entire universe is flying away from each other at a rate linearly proportional to its distance. That’s Hubble’s Law. The distance that light has to travel over time is continuously getting bigger and you MUST take that into account.

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Remember in my last post, we’ve established that the universe is expanding at roughly the Hubble Constant, and that number is a function of time. It matters WHEN you take your measurement of the redshifts of far away galaxies. Right now, the universe is expanding at about 71 km/sec/Mpc and is accelerating.

A somewhat simpler way to think of the expansion rate of the universe is that it expands at roughly the age of the universe to the 2/3 power: AgeOfUniverse^(2/3). Unfortunately, it’s not simply a plug and chug formula, since the expansion is occurring continuously, you need to apply some calculus. Here’s the formula, but I’ll go through a simple example a little later:

Horizon-Eq
Illustration Credit: Ned Wright

The above integral just takes the ratio of elapsed expansion time to the age of the universe raises it to the 2/3 power and does this over the entire time the expansion is occurring.

What all of this means is that whenever you discuss the size of the universe, you need to apply a scale factor that is relevant TO THE TIME you are interested in. The issue of when is very important because the size of the universe, and the rate at which it was expanding has changed since the universe began.

So, for RIGHT NOW, the size of the universe has expanded to roughly 46.5 billion light years since the Big Bang.

Let’s break down the above integral into some smaller intervals and watch what happens. Let’s use 13 billion years as the age of the universe and let the universe expand for an average of five billion years at three different points in time: 2, 7, and 12 billion years after the Big Bang:

  • At age of universe = 2 billion light years: the universe has expanded by a factor of (13/2)^2/3 = 3.48
  • At age of universe = 7 billion light years: the universe has expanded by a factor of (13/7)^2/3 = 1.51
  • At age of universe = 12 billion light years: the universe has expanded by a factor of (13/12)^2/3 = 1.08

So combining these scale factors over the two intervals above, the universe has expanded to a size of:

(average distance light travels over interval of interest) * (sum of all scale factors).

Plugging in the numbers (we used an elapsed time interval of 5 billion years):
(5 billion light years) * (3.48+1.51+1.08) = 30.37 billion light years.

The 5 billion light year number above is the average distance light traveled in 5 billion years so the units are in light years.

Now, this is a discreet example, taking only three points in time, but already we have a number bigger than 13 billion light years. Since the universe is expanding continuously, we actually need to do the integral above and when you do that, the answer approaches 47 or so billion light years.

Actually, this is a little misleading, the number cited in the above paper does a different analysis and I’m doing something a little different that what the authors of that paper did, so I’m trying to make a number fit that was derived using different techniques in my example above and it won’t work out that way. Still, the end results are similar and nothing is really lost by doing that.

But, ignoring the details for a minute, what I’m really trying to do here is show that the size of the universe isn’t simply the light travel time over the age of the universe. The expansion of the universe requires that you apply a scale factor as outlined above.

If the math is confusing you, just remember this: that scale factor is important. It accounts for the distance the universe has expanded over the time period you’re interested in. It doesn’t go far enough to say that the size of the universe is simply the distance light travels over the course of the age of the universe. Since the creation of time, everything has gotten farther apart, remember Hubble’s Law: everything is speeding away from everything else, all the time.

So, when the Hubble telescope took the deep field images, it provided us with the deepest views we’ve ever seen into the universe. Those galaxies were approaching the farthest edges of our cosmic home, and they weren’t 13.5 billion light years away, they were much, much farther.

UPDATE: Here’s a good graph I found on Universe-Review.ca, they have kindly given permission for me to post this.

Universe-Inflation-1
Illustration Credit: Universe-Review.ca

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  • r06u3AP

    You have provided us with an excellent description of why the SIZE of the Universe is greater than 13.7 Glyr in radius. But the size of the Universe is NOT in dispute. The scale factor due to the expansion is WELL UNDERSTOOD (at least, I THINK that I understand it.)

    But you entitle this article “How Can We SEE Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?” and your final paragraph states:

    “…the Hubble telescope … provided us with the deepest views we’ve ever SEEN … Those galaxies were approaching the farthest edges of our cosmic home, and they weren’t 13.5 billion light years away, they were much, much farther.”

    I really don’t think so, Tony!

    The argument is about what is “OBSERVABLE”. OF COURSE there are objects out beyond the horizon! OF
    COURSE they’re greater than 13.7 Glyr away. But do we actually see them? NO! That’s why it’s an event horizon! There’s only been 13.7 Billion years worth of time for ANY electromagnetic emission from ANYTHING to travel across the Universe, regardless of the geometry and regardless of the
    expansion.

    Let’s see if I can simplify the problem. Let’s call the age of the Universe a “Cosmic Epoch”. Let’s further say that there are two objects, shortly after the big bang that are relatively close to each other. Now, follow what happens as the expansion pulls them apart to a distance of
    2 light-epochs from each other. The expansion is nearly constant, but since more and more expanding space is being added between them, the rate at which they separate accelerates as time marches on until they each go beyond their mutual event horizon, when their velocity relative to each other exceeds the speed of light. Just prior to that point, cosmically speaking, the image of one as seen from the other is just 1 Cosmic Epoch old and is doppler shifted down far into the microwaves if not lower. It’s just like watching something fall into a black hole approaching the horizon.

    So, there is obviously no way that the image of one object as seen from the other object can ever be greater than 1 epoch old; the universe has only been around that long! Which is also why you will never ever observe anything beyond the cosmic event horizon, which must >> of necessity

  • http://www.astronomybuff.com tony

    @r06u3AP:

    Excellent comment. Thanks for taking the time to leave it, I really appreciate it.

    I used to argue the same thing, until I read some texts and discovered that we can actually see these things from these distances.

    I will admit, that this topic is stretching my writing ability, so let’s see if this helps (taken from Ned Wright):

    “Another way of seeing this is to consider a photon and a galaxy 42 billion light years away from us now, 14 billion years after the Big Bang. The distance of this photon satisfies D = 3ct. If we wait for 0.1 billion years, the Universe will grow by a factor of (14.1/14)^2/3 = 1.0048, so the galaxy will be 1.0048*42 = 42.2 billion light years away. But the light will have traveled 0.1 billion light years further than the galaxy because it moves at the speed of light relative to the matter in its vicinity and will thus be at D = 42.3 billion light years, so D = 3ct is still satisfied.”

    The key phrase there is: light is moving from the distant galaxy “relative to the matter in its vicinity”.

    Taken from Ned Wright’s Cosmological FAQ:
    http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN.

    He is talking about the integral that I left above (which was also taken from his FAQ).

    Does this help?

    Thanks again for leaving that comment!

  • http://www.astronomybuff.com tony

    @r06u3AP:

    BTW, what’s the story behind that handle? It is quite unusual, I’ve been trying to figure it out, but I think it’s an inside joke or something, I’d have to know you to get it.

  • r06u3AP

    You are very perceptive, the handle is a whimsical sort-of inside joke. The hacker-esque “R06u3AP” refers to unauthorized wireless Access Points sometimes installed by people for convenience at their workplace, unbeknownst to their boss. The trouble with doing that is that they expose the company network and everything on it to unauthorized access by others outside the facility. Hence, they are termed “rogue AP”s. As a worker in the IT biz, dealing with wireless networks and the detection of such rogue APs, I thought it made a neat handle.

    BTW, I noticed that my original comment didn’t post in its entirety, I don’t know if there’s a limit or if you cut it off. In any case, I’ll attempt to post the rest of it here:

    …..Which is also why you will never ever observe anything beyond the cosmic event horizon, which must >> of necessity

  • r06u3AP

    ALWAYS be 1 light-epoch away in all directions, receding from the observer at the speed of light.

    To see anything more distant would require that the light from it travel backward in time! If there is any other way for EM radiation of any wavelength to have travelled for longer than 13.7 billion years in our Universe, I certainly cannot see how.

    If I’m wrong, just shoot me, because the reason I’m wrong must be totally beyond my ability to comprehend.

    I also have a problem with the article “Constraining the Topology of the Universe”. Now, maybe I’m just not smart enough to get my head around all the fancy math and all but I always thought that EM radiation obeyed the principle of superposition such that even if you do have patterns of the CMB sky repeating around the 2-sphere they would necessarily have to combine additively(?) with what is naturally there to begin with thus yielding an essentially random pattern with no detectable repetition anyway. But I admit, I am by no means a brilliant degreed cosmologist so I’m sure that those more learned than I would surely have thought of that all too obvious hitch and clearly knows how to extract random patterns out from, uh….., random patterns???

    Huh? Oh well, like I said, just shoot me because I’m just too dumb to understand it.

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  • Dominic

    I’m just curious,if the big bang happened hurling our matter (planet) at the speed of light and then a millionth of a milisecond later there was a flash of light we would never see anything untill we slowed down to sub light speed relative to said light,so how can anyone know for sure how old any observed light really is without knowing how the universe accelerated or decelerated relative to the singularity?

  • James Dunn

    I only have a trivial understanding of what is currently known about the Universe. However.

    1) My problem with your supposition is that we are using a scale factor as a fudge factor.

    2) The Hubble Telescope can detect energy that appears to be coming from beyond the limits of the distant galaxies it can see. So the size of the Universe is not known as yet.

    3) The apparent expansion of the Universe is not as yet conclusive.

    4) After the supposed Big Bang (interesting support, but still a theory), as the energy masses formed varying densities as the energies raced out into space (assuming for the moment that nothing travels faster than the speed of light, even though we now know that is not true; see “entangled pairs”) the energy bundles would dominantly be moving under the speed of light. Since mass at the speed of light supposedly is infinite mass and we would be living in fluidic space.

    If the mass is escaping at a rate that continues to allow accelerating expansion, then at no time would the masses have slowed down. Unless there were multiple forces involved that acted on the masses non-linearly. As such, no simple calculation would explain the age of the Universe.

    As I said, I only know a trivial amount regarding the Universe, but the supposition that the Universe is of any specific age seems to be nieve given all the variables we do not know about.

    With respectful guarded interest,

    James

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  • cosmo

    There is a simple reason why the scaling has to be taken into account, and while it’s true that you can say that a galaxy is “12 billion light years away” in our frame of reference, you have to remember that its redshift indicates (roughly) also how much space has expanded since the light was emitted by the galaxy.

    Here 12 Glyr is just a measured distance in time, not necessarily in space. While the light has takes 12 billion years to reach us, space has expanded since then. There is no real limit to how fast space can expand, though c is the maximum speed at which any information can move within space.

    Thus you can suppose that the object which we see at 12 Glyr is actually at 46 or more Glyr. It’s just looking at the same thing from a different point of reference. There’s no problem there, it’s all plain and simple general relativity.

  • http://www.ouija-board-store.com DragonOak

    It boggles me mind…….my head hurts

  • Charlie Shread

    Hi, to put it in simple words: my opinion would originally be a state-the-obvious in that it is impossible to see anything older 13.5 billion years away, because there was no light created before that time. Is this not true?
    But then again, you have almost made me reconsider this opinion with light traveling at a speed relative to other mass near by, which would mean you could see things further away. But I guess that also means that light has moved faster in our perception of time? This surely breaks the law that light has a constant SPEED (Distance/TIME). So I am a little confused at the possibility of light reaching us from further away than the age of the universe is. Please could you shed light (hehe) on these queries. thanks,
    Charlie.

  • Si7ver6

    How do you know how fast the universe is expanding and put that into a number? And wouldn’t the universe have to be expanding between us and a distant object to make it further away. Is the universe expanding in places other than the event horizon or is the universe streaching rather than expanding? How do you know the universe is expanding at a constant rate? How do you know that the speed of light has keep constant from the start of time? How can you tell the universe is expanding at all? How do you know the age of the universe? Is there a way to mathmaticly calculate the age of the universe or is it a theoretical number? It seems like it would be impossible to prove mathmaticly or scientficly that any numbers regarding the age or size or expantion or anything in general about the universe as a whole or even as a part. Are there things bigger than science or our own minds can understand? If there is the size and age of the universe would be two of them.

  • http://www.monroeinstitute.org Skip Atwater

    To get my head around all this . . . by the time the light from an object reaches us on Earth, the thing we are seeing has moved further away from us. Seems simple enough.

  • Wiz Shack

    The universe was never “born”…..based on 1 simple fact. “Matter or Energy cannot be created nor destroyed”

  • sil-chan

    James Dunn:
    You betray yourself with the “it’s just a theory” quote.

    A scientific theory is a set of ideas and formulae that describe the known facts about some phenomenon. A theory is a rather sound scientific principle with a lot of proof.

    While no theory can be proven in totality, a theory is still not a “guess” as you make it seem with those words.

  • meiliken

    Umm, yes, the universe is indeed expanding and all that jazz, but sorry, there is no way in hguman understanding, unless you’re divine or celestial or non mortal to know the age of the universe, or really existence. Without a common frame of reference, i.e. something before existence, there is nothing to calculate against. So anyone saying they know the age of the universe or existence is full of shit. Go back to the caves hippies, or stop doing drugs.

  • James

    I doubt the entire universe is expanding. We can only see a piece of it. There can always be something out there further away. We have only 1 perspective of the universe, and that’s from the milky way galaxy, we haven’t been to other galaxies yet. So I doubt such a general conclusion. There can be galaxies further out hiding behind the galaxies in front of your telescope and you wouldn’t be able to see past that.

  • Pot Head

    So…Basically, it’s like light is trying to walk DOWN the UP escalators? I mean I read all of this, and I understood most of it, but for people that might not quite catch it, would that be an acceptable analogy?

  • Phil E. Drifter

    ‘Things’ CAN travel faster than the speed of light, since a.) the ‘speed of light’ constant IS a constant because it’s the measurement of how far light travels in one year IN A VACUUM. Scientists have recently been able to ‘fudge’ the speed of light, as well as actually beaming light into (i dont know the word for it) but they’ve actually been able to see the light *arrive at it’s destination* before it’s left.

    try wrappin’ your head around that.

    Anyway…light follows the predictions of matter and must therefore then have mass, because when astronomers see distant stars ‘wobble’ it is because of the gravitational pull of the planets that then must be orbiting them.

    But because light only travels, ahem, at the speed of light, that doesn’t mean things can’t move faster than it, it only means that *we can’t see them moving faster*.

    I’m somewhat interested in this discussion, being amazed by the universe myself, so I’m going to subscribe to follow up comments.

    AMAZE ME!

  • Phil E. Drifter

    ps: it was a ‘no-brainer’ for me to understand the title question; as soon as I read it I already understood it; things blasting away from each other 13 billion years ago, just as a rough estimate, says we’d be 26 billion light years apart.

  • Chris

    Ok, really simple question here:

    If I just look at an object on one side of the galaxy (A) and an object on the other side (B), are the two objects moving away from each other at more than the speed of light? With my basic understanding of relativity, that surely can’t be possible, as from A’s perspective, B is moving faster than light speed away from it.

    Basically I’m asking that if I’m in the middle, and to my right I see an object hurtling away at 0.6c (let’s say), and to my left is another going at -0.6c, surely from the view of one of the objects, the other is going at +/-1.2c relative to it. How can that be possible. It goes over the speed limit of 1c.

    For the diameter of the universe (in light years) to be bigger than the age (in years), that would have to be possible, but I don’t see how. Saying, “relative to the matter around it,” doesn’t really seem to solve anything, as what about “relative to the matter on the other side of the universe speeding away from it”?

    This is why I don’t feel I can begin to accept your scale factors as a solution (not that I really understand them, but as long as they don’t change the restrictions of light speed, I don’t really see how they’re relevant).

  • Daniel

    “For the moment, we lack completely the intellectual instruments to envisage in new terms the framework within which we could achieve our goals.”

    -Michel Foucault

  • Greg

    The problem I see with this is the idea of redshift. It is only an assumption that the shifting of the electromagnetic energy observed from distant objects is the result of its movement relative to us. In actuality it is quite possible that this shifting is the result of the distance that the waveforms are traveling. Instead of slowing down the speed of light from these observed galaxies losses its energy indicated by the shifting; that is as an electromagnetic wave looses its energy through time and distance both its frequency and amplitude diminish. Remember space is not a vacuum. The quantum ‘soup’ is all pervasive throughout space. The greater the time an electromagnetic wave spends travelling through this quantum soup the greater the potential to interact and loose energy; again both through amplitude and frequency. The so called microwave background radiation is not a remnant of the big band but the source of even further objects, which if its total energies where virtually amplified you would no longer have a dark sky; We would have a bright sky at night, as if the sky was filled with stars. In fact we do have a sky filled with stars completely, but because the distance of these stars and galaxies is so far they shift so far that we no longer see them. There is no end boundary to the universe, we can only see so far because of probabilities, the greater the distance the less the probability to observe.

  • Asadow

    Hmm… it’s a bit confusing, but first of all we should differentiate 4 things: size of the universe, size of the observable universe, distance to the object when the light which is reaching the observer now was emitted, and distance to the object at the moment in time when it’s light is reaching the observer.
    Now:
    1. Size of the universe – speed of light has nothing to do with it (at least there is no simple, direct relation). No object can travel faster then light but this doesn’t necessarily apply to the space, right?
    2. Size of the observable universe = age * c + expansion factor. Light is LOCALLY traveling with the… speed of light, but as the SPACE itself is expanding, so the effective speed is higher.
    3. Distance to the object when it emitted the light we see: will be bigger than c*t (t – relative age of the observable object) because of the space expansion.
    4. Distance to the object NOW, when the light it emitted is reaching us: like above + the distance the object went according to the Hubble principle (integrated with Hubble const. variable in time).

    But isn’t it that if the light is moving like the traveler going on a moving walkway (like they use in airports) ? We have source galaxy at the fixed end of the walkway (space between us and the galaxy) and we are moving on it (resting relative to the walkway’s surface) – as the universe expands. Now the galaxy emitted a photon (traveler) which is walking on the walkway (the later is actually changing speed, never mind). When the traveler/light is reaching us, the distance between us and the galaxy is bigger than the speed of light (speed of the traveler walking) multiplied by the time it has taken to reach us.
    In Special Theory of Relativity all observers would measure the same speed of light, regardless of their relative speeds, but this is not applicable when the space itself is expanding.

  • Jonathan

    @Phil

    The speed of light is a velocity, not a distance, but you are right in that the typically quoted speed (300,000 km/sec) is its speed in a vacuum. That being said, scientists can slow light down by passing it through various materials, but they cannot speed it up. No information, or “things,” can travel faster than the speed of light. Perhaps what you are referring to is the fact that you can slow a beam of light down, and thus beat that beam of light to its destination.

    Light does NOT have mass. Photons are massless, but they follow the gravitational curvature of space, and thus are affected by strong gravitational fields. This has nothing to do with orbiting planets, however. See information on “gravitational lensing” for an explanation of light being effected by gravity.

    Things in the Universe CAN be farther than 13.7 billion light years apart, due to the inflationary epoch seen on the above graph, but we cannot SEE anything that is farther away than 13.7 billion light years. During inflation, space itself was expanding, and thus objects were flung apart at relative speeds greater than the speed of light. Since space itself was expanding, nothing was actually traveling faster than the speed of light. However, since the Universe is only 13.7 billion years old, light emitted from objects that are farther that 13.7 billion light years away has not had time to reach us yet. Thus, we can see 13.7 billion light years in every direction, and no farther.

  • http://current.pic.tv Colin

    Please correct me if I’m wrong. It seems you are trying to say the visible light from some distant galaxies were first emitted 13.5 billion years ago (our event horizon) but because of the rate of expansion, some of those galaxies are now over 40 billion light years away from us and moving further away.

    Correct? Am I missing something? Thanks for the very intelligent post.

    Cheers,
    Colin

  • Symber

    This is just a response to r06u3AP, who – while making good points I believe missed one key thing, which is what I believe Tony was trying to point out.

    I believe he is saying that the objects pictured in the Hubble Deep Field were indeed 13.5 billion light years away when the light embarked towards Earth… but in that 13.5 billion years that the light was travelling, the actual objects pictured have continued to get farther away to the point where they were about 46.5 billion light years away when the light reached the Hubble telescope.

  • Common Sense

    scientists don’t know how old the universe really is. that’s why.

  • Al

    Here’s an easy way to picture it. Take two people Mr. A and Mr. B and put them at either end of a flat escalator measuring 100 ft. Have Mr. A roll a ball toward Mr. B. By the time the ball reaches Mr. B it’s traveled 100 ft. Now Start the escalator traveling toward Mr. A at half the speed that Mr. A rolls the ball. The ball has to travel 200ft before it reaches Mr. B 100ft away. Lastly add a constant acceleration to the escalator and have Mr. A roll the ball to Mr. B. You can do the math.

  • http://none zboson

    Well, here, try this. Suppose light left a galaxy 5 billion years ago about the time our sun was being formed. We see the galaxy as it was 5 billion years ago. But, where is the this galaxy right now? 30 billion light years away according to the above calculation by the OP. Light leaving this galaxy today will arrive at our solar system (or where our solar system used to be) in 30 billion years.

  • Al

    Sorry to post twice here,

    Phil:

    Things with mass cannot move faster then the speed of light. As velocity approaches the speed of light, mass approaches infinity (see Einstein’s Theory of Special Relativity.) Since the universe does not contain infinite mass it is impossible to travel faster then c. Also, since energy = mc^2 that means that it would require infinite energy to accelerate anything with mass to c. The universe doesn’t contain infinite energy either. But since energy and matter are the same thing in different forms it really doesn’t matter.

    Traveling faster then c doesn’t really mean traveling faster then c. We know pretty much nothing of the universe. Discovery and Technology are exponential. Sometime in the future we may be able to say… fold space, make the speed traveled 0 but the distance traveled quite a long way. But in the end anything with mass can never travel faster then the speed of light and speculation lays in the fiction part of science.

  • http://pajarittaazul.blogspot.com lulu

    fuckin nerd, you rule!

  • tim

    what a dumb page. the answer to the original question is simple… the question is meaningless.

    the idiot who asks the question thinks that light ‘years’ are measurements of time instead of disance. the question is fallacious.. exactly like… ‘how can london be 200 miles from liverpool when it’s only 3 hours since i had breakfast’

  • Jack Jaeger

    The universe is expanding into what?

  • http://hed.com hede

    Your logic is flawed. We wouldn’t be able to see galaxies which are 45 billion years away if the universe wasn’t older than 45 billion years. Because these 45 billion years far galaxies’ light takes 45 billion light years to reach us ergo universe is older than 45 billion years.

  • Vlad

    I became outraged before I even finished the article but wanted to see where it was going. Then it turned out that the very first post was talking about the issues I have with this article, so I will only contribute to it without restating what has already been said. So r06u3AP, no need to die, you’re absolutely right, I have been interested in astronomy since I learned how to read and have taken 2 years worth of astronomy courses in University of Toronto with professors who have been working among other things on research such as expansion of the universe, observations of the hubble, detecting the weakest of energies from outer space, etc. Tony, way to confuse us with your explanations and changing the subject… Going in chronological order, Dominic, we were never moving at at a speed of light, and especially relative to anything else. Funny you should use the word relative, since it is the theory of relativity that states that something magical happens as you approach the speed of light – time slows down, matter turns to energy, etc. One of these effects, the time change, will make sure to compensate for the fact that something else might be moving away in the opposite direction at the speed of light – it wont appear as such, physics as we know/percieve it breaks down. As for knowing the age/distance of observed light, astronomers know it with astounding precision using many fairly straightforward tools such as the doppler shift. Unfortunately I can’t for the life of me recall the whole procedure, but I’m sure if you look up this information you will find it in a breeze. Now James… oh James, “2) The Hubble Telescope can detect energy that appears to be coming from beyond the limits of the distant galaxies it can see.” The energy the Hubble detecs IS what it can see! “3) The apparent expansion of the Universe is not as yet conclusive.” The only thing not 100% conclusive is whether it is slowing down, accelerating uniformly, or speeding up. And even then, there is most evidence for the speeding up scenario, e.g. doppler shift again. “4) After the supposed Big Bang (interesting support, but still a theory), as the energy masses formed varying densities as the energies raced out into space (assuming for the moment that nothing travels faster than the speed of light, even though we now know that is not true; see “entangled pairs”) the energy bundles would dominantly be moving under the speed of light. Since mass at the speed of light supposedly is infinite mass and we would be living in fluidic space.” WOW – so you consider Big Bang, expansion of the universe, theory of relativity (nothing travels faster than light), and the fact that in your words “unless there were multiple forces involved that acted on the masses non-linearly” all just supposed propositions, but the far-fetched, new, theory-in-progress idea of entangled pairs as something “we [] KNOW [] is [] true”? And what is with mass at the speed of light being infinite mass? It isn’t, it just turns into energy, IN THEORY. The next thing you said is the most amusing “fluidic space”, at first I just thought “what the hell?” Then my Sci-Fi fan girlfriend laughed, it’s from Star Trek… Phil: now I don’t know at all what you’re talking about (in a good way), but I wrap my head around what you said by thinking maybe there was more than one scientist involved and/or there were devices at the other end to detect the light, I don’t think one guy sent a beam and ran to the other end to catch it… Also, what does seeing stars wobble have to do with the fact that light has mass? I apologize to anyone offended by my comments, it is just the way I talk, I’m an asshole, but I also feel like people need to have a better understanding and a broader idea about subjects before they talk about them, and especially write about them, listen more and talk less. Take a course in university and get the info first hand from the people that are involved in research thenselves – my prof was the guy that led the research in antarctica 3-4 years back (hope that’s enough info to google). Internet is a wonderful place except that you can’t believe most things on it because of, well, shit like this (just a figure of speech). Looks legit to most folk…

  • Chris S.

    The age of the universe is about 13.5 Bn years, meaning we can’t “see” any further away than the 13.5bn light years, IF the universe was static.

    However, Just for simplicity of explanation – assume the following, and it might be easier to understand how things relate:

    Two cars (galaxies) are sitting next to each other, parked, at a distance of 100km. The speed of light is 100km/h, and hour universe is 1 hour old.

    For us to see the light from the other galaxy, we would have to wait 1 hr for the light to travel 100km.

    Now, assume that we instead have a universe that is expanding at a constant speed, meaning that the cars are driving away from each other at 10 km/h.

    The light begins it’s travel from the observed car at a given point in time (1 hr), but when it arrives at our car, we will see it as it was 1.1 hour ago, this because the light has had to travel the extra distance we have traveled in that hour – that is the extra 10 km. (the speed of light is 100km/h relative to space, but relative to us, it’s 90km/h, and this is why you get the red or blue shift)

    This means that while only 1.1 hour has passed when we observe the light from the other, the other car, is actually no longer 100km away, but the initial 100km, plus the 10km it has traveled, plus our 10 km, making a total of 120 km, and while our light is only 1.1 hour (10km = 6 light minutes or 1/10th of the hour), what we see, is actually 1.2 hour away, however, we just do not see it as it is now, but as it was 1.1 hour ago.

    Now, remember that when we observe the light from the othert car, our universe is actually 2.1 hours old.

    So, while our universe is only 2.1 hour old, we would actually be able to see the other car at a distance of 2.2 light hours.

    This is due to the expansion factor of the distance between the cars, or the speed at which the cars drive away from each other, which in this case is 1.2.

    This means that if we actually detect something being 30 minutes away (50km), it is actually 36 minutes (60km, or 30km + 3km + 3km) away when we see it, and likewise, 200km means 240 in reality, as you would have distance = expansion factor * time, where time is actually a distance in relation to our location.

    The speed of the light is constant, but ours is not, as the universe is expanding, which means the distances in light years that we can see, grows beyond the age of the universe.

    However, we can not see any further back in time than 13.5bn years, as that would be looking beyond the inflation (big bang), but as you can see from this, we can actually see objects a whole lot further away than 13.5 bn light years.

    Distance is equal to time * speed, but again, since the speed increases over time, you can see that distance will not be linear, but actually grow as we look further away.

    Hope this has managed to explain it in a bit simpler form, without any complicated maths.

  • Arun

    If the universe is only 13 billion years old…….then the maximum possible diameter or width of the universe can only be 26 billion light years…..not more than that….since any radiation/particle/object cannot travel more than the speed of light, lets assume 2 particles exploded in exactly opposite directions travelling at the speed of light….those 2 particles would now be 26 billion light years away. simple.

  • USFBULLSROCK

    OK, I posted this on another site. Maybe someone here can give me an answer. Since the big bang our universe is expanding and accelerating faster than the speed of light. How is it we can see objects on the other side of the universe? To paint a clearer picture, the big bang happened at a certain point. The stuff that eventually became our galaxy went in one direction while other stuff went in the other direction (yes I know in all directions). So if we are now traveling faster than the speed of light, how can we see past the point of the big bang to see the other galaxies traveling in the other direction in the same speeds? Wouldn’t it make sense that we can only see galaxies on our half of the universe since light travels at a constant speed? Which means it would only be possible to see half of the universe. Depending on the vectors of the other matter traveling we would see dimmed versions of other galaxies (redshift). Is that understandable???? Someone please let me know.

  • Joe Alien

    @Phil E. Drifter: You assume much in your statement. Keep in mind that “space” is not shaped as you think it is (relative to stuff blasting apart from each other). The shape of space may be more like the surface of a balloon as it expands (not the stuff inside the balloon). Imagine you on the surface of a balloon. As it expands, what you would see over time?

  • USFBULLSROCK

    Joe Alien: So if space is like the surface of a balloon expanding, why can we see galaxies and stars in all directions? If space is shaped like the surface of a ballon, from our view everything in the viewable universe should be viewable as an arc from our perspective. That makes no sense. So what’s inside the balloon? That logic makes no sense.

  • sonofaphysicist

    First, a few things:

    1) Before the Big Bang, there was no space and time. The Big Bang is the creation of space and time and so it occurred EVERYWHERE in the universe (as the universe is space) at approximately 13.7 billion years ago. The Big Bang did not happen IN space.

    2) The universe is expanding at an ever faster rate (initially inflated by negative-pressure vacuum energy density and now accelerated by something called dark energy). Imagine a balloon with 2 colonies of ants on it. Initially the distance for an ant to travel from colony A to colony B is very close. But as the balloon gets inflated continuously, the distance between the 2 colonies increases but the speed at which the ant moves is constant. So when that ant tells colony B that it took him 1 hour to arrive from colony A, it would actually take a second ant from A 9 hours at that moment in time to get to B now moving at constant ant speed due to that inflating distance.

    3) The diameter of the visible universe is approximately 93 billion light years. To simplify things (Galaxy A and B are at the edge of the universe), let’s say you point Hubble in one direction and observe light from Galaxy A that departed 13.7 billion light years ago near the instant of the Big Bang, it would take light 46.5 billion light years to reach you if that light were to leave Galaxy A right now. If you whip Hubble around 180 degrees to observe Galaxy B, you would see 13.7 billion-year-old light arriving, but Galaxy B is now 46.5 billion light years away. Add those two distances up and you get a diameter of 93 billion light years. You can think of the visible universe as a sphere with a diameter of 93 billion light years.

    4) The universe is much bigger than the visible universe at 93 billion light years. See my crude drawing below:
    Galaxy A ——–Hubble——–Galaxy B
    An alien in Galaxy A maybe able to observe the Milky Way at the edge of HIS visible universe but he will not be able to observe Galaxy B, and vice versa. The universe maybe infinitely big as far as we’re concerned because we will not be able to observe anything beyond our observable universe.

  • http://j.chistopher60@yahoo.com christopher

    what proof is there to say there are no other universe in existense there could many universes in existense which could be billions and billions of light years away.

  • http://j.chistopher60@yahoo.com christopher

    there could be hundreds of universes beyond can you proove there is just one universe in existense?

  • Stephen Garramone

    Seems like you are saying the universe is some 14 billion years old but the distance to the furthest object we can “see” is some 40-50 billion years. That means the expanding universe carried the most distant objects out such that light travels some 40 billion light years when in original time it would have travelled only 14 billion light years. Hence, the expansion of the universe is actually functionally increasing the speed of light because that object we see at 40 billion light years is really only 14 billion years old.

    Does that make sense???

  • http://www.mdmcp.com Mark

    If the universe began with the big bang and expanded spherically for simplicity, photons from the “edge” of the expanding sphere would travel toward the center–or in every direction for that matter–since ALL particles in the universe are part of the bang they must be able to see “each other” ALL OF THE “TIME.” Since the expansion is at a rate “less than the speed of light” all of the universe MUST be observable by all other parts. Otherwise there would be an “expanding” event horizon as the “sphere” of observability would be expanding faster than the expansion such that the “new parts are revealed” as the radial spherical event horizon expands by one light year every year.

  • http://www.mdmcp.com Mark

    The balloon surface analogy is interesting. Consider that the universe is “flat” or as flat as we small bugs on a big balloon can measure. Now consider that the big bang occurred 14 billion years ago and we are on the SURFACE of a “balloon” with radius 14 billion light year radius. The “distance” to the furthest part would be Pi times 14 light years away AND expanding faster the further it is away from us. This makes the “perceived” maximum distance 43 billion light years and expanding faster than the closer portions. Of course we can “see” everything in “our” balloon since it was on the balloon and close enough to see from the original bang and will always be that way. The universe is as “flat” to us as a sphere 14 billion light years in radius.

  • Stephen Garramone

    If one object is moving away from an arbitrary point (call it 0,0,0) at +c and other object is moving away from 0,0,0 at -c they are not moving from each other at 1.2 c. Time dilation, also part of the Relativity theory states that they are travelling from each other at 0.7296 c

  • Stephen Garramone

    I correct myself from above.

    use the same reference point 0,0,0. If an object is mocing away (on the x-axis) from the origin (0,0,0) at +0.6c and another object is moving away from the origin (0,0,0) on the x-axis at
    -0.6c, their relational velocity to each other is NOT 1.2c.

    It is ((0.6c -(-0.6c))/(1 + (0.6c * 0.6c)/c^2) =
    (0.8823…)*c which is NOT > c.

    Source: Einstein A. Relativity by Einstein The Special and the General Theory. New York 2005 Tess Press, 40.

    Remember, you never, never, never can bust the speed of light or “c” as it is represented.

    Second question… I cxannot discern it from the blogs. Have “we” (I mean astronomers) seen, by whatever means, stars or radiation or anything some seventy or eighty billion light years away. I don’t mean have we extrapolated to that, I mean have we seen it with astronomical tools?

  • http://sadfasdf.com Jebus

    So are you saying the universe is expanding at about 3.6 times the speed of light?

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  • FeTaL

    The point that tony has made is correct but the question “How Can We See Galaxies 47 Billion Light Years Away When the Universe is Only 13 Billion Years Old?” is incorrect. Because we cannot see galaxies 47 billion light years away. but we can see what a galaxy that at this very moment is 47 billion light years old looked like when it 13.7 billion light years ago.
    Two Galaxies Us and our FriendGalaxy which is 13.7 billion light years away are traveling away from each other increasing speed constantly. Our FriendGalaxy takes a picture of himself and sends it to us in a photonEMAIL which can only travel the speed of light. We Receive our FriendGalaxies email 13.7 billion years later. we have continued to move apart. meaning when we received the email not only has 13.7 billion light years passed we have also moved even further away making the distance between us and our friendgalaxy 47 billion light years away. So we can see what our friend looked like when he was 13.7 billion light years away. but we will never be able to see what he looks like now or any time after 13.7 billion years ago. Hopefully i did not make that more complicated than i originally had it in my head.
    and correct me if i’m wrong.

  • http://utenti.lycos.it/fxcuqos/cheap0e4.html pGakefeses
  • Mark

    While it is correct that the photons arriving were produced NO LONGER than 13 billion years ago–however–photons don’t age or have rest mass–we will ALWAYS be able to see that galaxy AND what it looks like “now” EVENTUALLY!!! It is simply impossible for us to “have seen it” and be CONSTANTLY RECEIVING PHOTONS at some PRIOR TIME and then suddenly STOP SEEING THE PHOTONS.

    We will simply be able to see what that location looks like NOW (there) in 47 billion years!!!! (at which time it will be, what, at least 94 billion light years away, more likely 200 billion light years away!!!)

    It will NEVER DISAPPEAR!!!–unless quantimechanically the solid angle of the source becomes so small that we only see as a packetized source which begins to “flicker”–but that is still DATA about its then/was configuration.

    Stop thinking about space as three space and start thinking about the 3 space we see as the surface of an expanding sphere with dark matter being converted into the sphere (space itself) and dark energy proving the energy to expand the sphere–making things blow apart–because they are in the same place in space AND SPACE IS EXPANDING BETWEEN THEM–they are not moving through space–except to the extent that they are governed by the forces we can measure interacting among each other within the space that exists.

  • Steve

    Mark,

    It would appear that you are saying that although light itself moves at 300,000 km/sec, the expansion of space itself makes the actual distance become the 40+ billion light years and the light, which would have normally travelled some 13 billion light years has appeared to travel the 40+ billion light years in the same time (the 13+ billion light years).

    It isn’t that light has picked up speed, but that space itself has expanded which puts an additional “kick” into the speed of light.

    This, of course, would not be reflected in a Doppler red shift as the space that light is in makes the wavelengths still the same as they would have been if space did not expand.

    This is almost as bad as the the stimulus package which is expanding faster than the speed of light.

    We hope President Obama has a way of slowing it down.

    DO I HAVE THIS RIGHT?

    Steve Garramone,
    Melbourne FL

  • Mark

    It is the expansion of space that causes the doppler shift. It doesn’t matter to us if the light source is moving away from us or if the space between us is stretched, there is still a doppler shift.

    The only way I could think of this is to think of THREE space as actually being the same as TWO space on a sphere. Consider that the big bang was a point and that the explosion burst the point OUTWARDS. There is NOTHING at the center–JUST THE SURFACE. And it is expanding because the “energy” (dark energy) of the explosion is not depleted. That is the only construct I can come up with that provides for the “energy” to have all objects moving away from each other at increasing speeds!!! The “dark matter” is just like the surface of the sphere expanding being CONVERTED into space. It affects light because it is SPACE–just crunched up–not fully stretched space.

    The “sphere” metaphor is also good in that the expansion is from the edges. Multiply Pi times 13 billion and you get nearly 46 billion–add the “inflation” and you can get there. There is a lot more complicated mathematics that I don’t understand, but how else can stuff be further away than there is time for if it all started from the same spot?

    I hypothesize that there will be no NATURAL interaction between dark matter and ordinary matter because dark matter is being converted into SPACE and has the characteristics of “lumpy” space which disrupts light. As the dark energy wears down it will stretch the lumpy dark matter into smooth ordinary space until there will be nothing left other than the regular matter far away from itself in a smooth energy less/dark energy less space.

    You will ALWAYS see anything YOU CAN SEE–AND WE CAN SEE THE ENTIRE UNIVERSE (from the original big bang) because at ONE TIME IT WAS CLOSE ENOUGH TO SEE–zero distance or certainly less than 13 billion light years. Since we DID SEE THEM–and they cannot be moving away faster than LIGHT–WE WILL ALWAYS SEE THEM–just getting dimmer and red shifted away and with a big time delay.

    The “seeable” universe is also a falacy because there would be an expanding zone of new seeable stuff as the “seeable” event horizon would be expanding and MORE NEW STUFF would be seen which is not the case.

    Imagine the sphere analogy that says you look in any direction to infinity–around the sphere to the other side.

    No illegally topologically change the sphere into a flat surface with infinite edges from your perspective–but everyone has the same perspective. Hence everyone sees the universe expanding AWAY from them when it is all connected.

    The disappearing universe is a contradiction. Consider I DID SEE YOU. You cannot be moving away from me faster than the speed of light. Hence I will always be able to see you! qed/wzbw Also it follows: We can SEE THE ENTIRE UNIVERSE NOW!!! The far stuff is just getting hard to see and the information is becoming very dated.

  • Mark

    On the Obama stimulus package. Just keep in mind one thing: It is the WORK that makes the money strong, not the money that makes work strong. What would your savings or anyone’s for that matter be if we all stopped working tomorrow!? The stimulus package needs to CREATE something of VALUE that can be used to reduce future costs or improve future productivity.

    Perhaps the auto workers should GO BACK TO WORK and produce really INEXPENSIVE CARS! Or we should build 50 nuclear plants–if the operating costs/not capital costs are LOWER than producing electricity from coal. Or we could build 5,000 windmills if the operating costs were less than coal!

    But as an economist, IT MUST BE THAT even the operating costs of wind power cannot compete with the fully loaded cost of fossil fuels–so dig and drill we do.

    The roads and infrastructure of the post war provided for MASSIVE efficiency in goods movement along with CHEAP gasoline. Add to this the benefit of running water and air conditioning to make the southwest habitable AND diesel fued used in farming and you have the economic drivers of the last half of last century.

    Women in the work force and computers drove the 80-2000 boom. Thinking everyone was productive and creditworthy caused the financial boom of 90-2008.

    Fundamentally, what Obama faces is a means to be sure that the entire population is PRODUCTIVE because it is THEIR WORK that makes the economy strong.

    As a physicist, in the auto industry: if wages are the problem for costs in the industry–why would you pay people 80% of their pay NOT TO WORK for two days. Shouldn’t we take all of the auto workers that are being paid AND PUT THEM TO WORK DOING WHAT THEY DO BEST–making cars! Doesn’t having them work FIVE DAYS while paying them FOR ONLY ONE MORE provide lots of productivity!

    And the assets in your bank are only as good as the promise to pay (ability to pay and to be productive) of the person borrowing the money. Think of it–when someone “stretches” to buy a house they are actually committing to give 20-30% of their income for 30 years. All of that future value has been converted into an asset we consider as liquid as CASH. (Which of course is only the governments promise to pay you–tomorrow–and your ability to make someone else accept that promise for their work today!) [Of note: did Popeye ever give Whimpy a hamburger today?]

  • Steve

    Mark -

    I was tongue-in-cheek about the recovery stimulus… I just thought that it was interesting about the similarity in numbers between the National Debt and the age of the universe…

    I still cannot wrap brain around this 40+ vs 13+ billion years…

    Is the universe 13+ billion years old or 40+ billion years old.

    If it is 13+ billion years old but 40+ billion light years in radius from us then light must have travelled at 3 times the 300,000 km/sec or some 600,000 km/sec in order for us to see that far.

    OR

    Because the universe is expanding so fast that relative to us time slows down (time dilation) and in its own framework the light it ihas travelled for only 13+ years while in our framework that is 40+ billion years

    OR

    length contraction – same relative reasoning. 40+ billion light years in its own framework is equivalent to 13+ billion light years in our reference.

    Thus, we “think” time has existed for some 13+ billion years but in reality, it has existed for at least 40+ billion light years. By your reasoning, it could be virtually limitless as the faster one goes, the more length contracts or time expands so there is no limit as the denominator
    sqrt [(c^2 - v^2)/c^2] approaches zero.

    (Lorentz Transformations)

    That Lorentz guy and the others who worked with him or before him (he was not alone) were bloody geniuses.

    Pretty soon our National Debt will exceed any conceivable Lorentz calculated figure, so maybe he wasn’t such a genius after all.
    Maybe I am a simpleton

  • matt

    no one knows how old the universe is haha i think its funny how you all think you know so much when really you know nothing at all.

  • http://www.donthaveone.com Private-Freedom

    Tony, please help me understand this correctly. I say something, and you tell me if it makes sense.

    Are you saying that the universe is bigger *now* than how far the light traveled from the furthest images we can *now* see?

    In other words, yes, the light from the deepest part of space that we *now* see took 13.5 billion years to get to us, but because whatever made that light has since moved away from us (Hubble acceleration), those deep space objects are now in excess of 47 billion light years away?

    If I give you an example using the principle I am talking about, maybe it will be easier to criticize what I am saying.

    Imagine two rocketships traveling in space, one following the other at a current distance of 1 light year. Imagine that the rocketship in front is traveling at 1.5 times faster than the second rocketship. The distance between the two will increase over time naturally. We can treat these two rocketships as stars or galaxies or whatever.

    Now imagine that the rocketship in front points a laser beam back towards the second rocket ship. After one year, the laser will reach the second rocketship and the astronauts onboard will observe the light. Of course they will say aha, that laser must have started *at least* 1 year ago, because the second ship astronauts didn’t see it before (imagine they can see light more than 1 light year ahead using their onboard telescope).

    However, during the last year, when the laser light was traveling, the first rocketship has since traveled away from the second rocketship at 1.5 times the original distance, the astronauts in the second rocketship are observing light from something that *now* exists much further away than 1 light year.

    If we proxy the two rocketships as marking the extremities of the universe, then the example generalizes to mean that the light that we think is coming from objects 13.5 billion years away actually came from objects that are *now* much further away because they have accelerated away from us since they shone the light that we now see!

    Am I getting this right?

  • Jeremy

    This is a terrific post. Your description plus the links answered so many questions that I have.

    I guess I’m wondering one thing, though. I did a search on what the most distant galaxies we’ve seen are. What I found was A1689-zD1 (http://blogs.discovermagazine.com/badastronomy/2008/02/12/hubble-and-spitzer-find-most-distant-galaxy/) which was viewed by Hubble and Spitzer. But that one is only something like 12 billion light years away and the various articles say it formed just after the “Dark Ages” of the galaxy. So is it correct to say that even though we could theoretically see a galaxy that’s 47 billion light years away, we never will? If a galaxy that is just 12 billion light years away was formed at the beginning of the universe, how could we ever see a galaxy that is farther away? I can’t quite articulate my question, but how do we know that A1689-zD1 is at the beginning of the universe if we could theoretically see something that’s much farther? Sorry for the clumsy question and again, thanks for the post!

  • Jeremy

    correction: I said that A1689-zD1 formed just after the “Dark Ages” of the galaxy. I meant the “Dark Ages” of the universe.

  • Greg

    Uh, doesn’t this then violate the principle that nothing can travel faster than light. If the universe is 16.8 billion years old, but it was the size of a pin head before the big bang, but since then (it’s birth) it has spread out to a size of 47 billion light years, isn’t the universe expanding at a rate faster than light travels? Hence moving at a rate faster than light travels?

  • Michael

    So I’m interpreting this as the distance from the point where the photon originated might be X light years from us, but because of the expansion, the actual thing we’re observing is now further than that.

    So when you say that we’re “observing” something further than 13.5 billion light years, you really mean we’re receiving photons that originated closer than that, but those photons were emitted by and thus represent objects that are now further than that.

    Is this an accurate take-away, or is the issue actually more subtle?

  • TheRafMan

    Did anyone ever see the “Powers of 10” video where everything microscopic eerily resembles everything astronomic? (http://www.youtube.com/watch?v=A2cmlhfdxuY)
    Sorry to crush everyone’s dreams but the big bang was nothing more than a spark plug ignition in someone’s engine, our perceived universe is contained inside one of the engine’s cylinder and the human race is nothing more than parasites on one of the billions of atoms that could be either exhaust or unburnt fuel. What if? What if our perception of our universe is nothing like we try to imagine?
    My head hurts thinking about how meaningless we are compared to the scale of “our universe”…
    My head is o the verge of exploding when I think about the possibility that we are in someone’s Formula 1 engine that revs at 20,000 RPM, the equivalent of 5,000 big bangs in one minute or 83 big bangs in one second when we are currently living through only one of those big bangs.
    I better stop and go to sleep before I cause my self an aneurysm.

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  • Abdul Rahim Bin Osman(Singapore)

    tim
    Sep 15, 2008 at 3:46 pm

    what a dumb page. the answer to the original question is simple… the question is meaningless.

    the idiot who asks the question thinks that light ‘years’ are measurements of time instead of disance. the question is fallacious.. exactly like… ‘how can london be 200 miles from liverpool when it’s only 3 hours since i had breakfast’

    Oh, yes, Tim got it right that the question itself is meaningless at all.

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  • pooldaemon

    “At age of universe = 2 billion light years:”
    You cannot measure the age in light years!!!!!! Fix this please!!!

  • http://math.expectable.net victor

    This is a hilarious question indeed. Are you trying to confuse people or yourself? You are comparing time with distance? The question is basically similar to this one: how can 3 kilometers larger than 2 hours? How do you answer this question? Isn’t this hilarious?

  • Stephen Garramone

    Let’s not get insulting to each other by denigrating or poo-pooing anything anyone says. After all, none of us were around when this all started.

    I have been taught the the unversal constant in the ubiverse is the speed of light, some 300,000 km/sec. One cannot add a linear velocity onto another linear velocity and come up with a final speed greater than c (or 300,000 km/sec). Thus, on the x-axis, and object or frame of reference (call it “A”) travelling to the right at, say 200,000 km/sec relative to the origin, then a second object (call it “B”) travelling to the right with respect to “A” is NOT travelling at 400,000 km/sec with respect to the origin. There is some formula somewhere that tells what it is (obviousy from the Lorentz equations of 1903-4.) But this is beyond my paygrade to know what that is.

    So, someone, please help us out. If you answer that question, this mystery will unfold.

    The applicable Lorentz transformation is on page 34 “Relativity,” by Albert Einstein (translated from German) but I cannot make heads or tails of it.

  • Stephen Garramone

    Addendum:

    That sentence should read, “Thus, on the x-axis, an object or frame of reference (call it “A”) travelling to the right at, say 200,000 km/sec relative to the origin, then a second object (call it “B”) travelling to the right with respect to “A” at 200,000 km/sec is NOT travelling at 400,000 km/sec with respect to the origin.”

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  • Mark

    USE THE SPHERE ANALOGY. The surface is expanding because the “sphere” is being blown out from the center. Our “universe” is the surface of the sphere (or more complicated conic). It is “expanding” and further points are expanding away faster as the sphere expands the points on the sphere are moving away. We are all 47 billion light years from the furthest point AND THERE IS NO EDGE OR END–just like no edge of a sphere. The energy “expanding” the universe could be the dark energy with the dark matter becoming space–surface of the sphere. It will eventually slow down when the dark energy is dissapated and dark matter has been converted into space. But as long as the sphere is GROWING the universe is expanding and the objects are moving away from themselves faster than they were yesterday.

    The time / size question is relevant in that the Big Bang BOUNDS the problem with space and time equal ZERO at big bang. So how does something get to be further away than light and time allow.

    Force and energy expanding universe are not acting in THREE SPACE.

  • TheRafMan

    Regarding Stephen Garramone’s Addendum:
    Why not? Because of Einstein’s Relativity theory that says nothing can travel faster than light?
    If the two objects where going in opposite directions, relative to each other, A and B would be traveling at the sum of their speed: 400,000 km/sec, but from the origin they would be appearing to be traveling at 200,000 km/sec in opposite directions. From m understanding, this is the basis of this article, if the universe is 13 billions years old and matter was still traveling at the speed of light since the big bang, from opposite end of the universe we would appear to be 26 billion light years away. It’s the 47 billions number I don’t get…

  • Stephen Garramone

    To Rafman -

    Not according to Lorentz. Using his transformation the two objects, travelling in opposite directions at 200,000 km/sec would NOT be travelling away from each other at 400,000 km/sec.

    I still cannot wrap my brain around it and I don’t know how to plug numbers into his formula.

    Anyone… HELP!

    Steve G

  • Chris C

    Just quickly, to all the people saying it’s a stupid question, you’ve got to think about what it means.
    For someone like me, who isn’t “stupid” about this issue, the speed limit of stuff is “c”. A light year is 1year*c. In one year, at speed c, you go a light year of distance at max speed. So, in 13 billion years, stuff can only go 13 billion light-years of distance. So, the universe must be a sphere with radius 13 billion light-years, so stuff must be at max 26 billion light-years away.
    This is what the average Joe would know, and one would not be stupid for thinking this, okay? This makes the most obvious sense.
    Now I know now that it’s actually a lot more complicated – what with expanding space and RELATIVE speed limit of c (something about “relative to local space”, and Lorentz?). Also, that’s just “how can stuff be 47billion light-years away…?”. ‘Seeing’ these galaxies is more complicated, because are we seeing them as they are now? as they were in the past, and when? how far were they then? how far are they now? does the expanding of the universe help or impede light’s journey from them? what do you mean expanding universe – what does it mean to “add space”? etc.
    That is what this article should explain – going into expansion factors and whatnot is all good and well once you’ve settled the more basic confusions for most people – and definitely a lot of the people (including me) posting here.

  • Stephen Garramone

    Further elucidation on Lorentz.

    The relative speed of the two spaceships, each travelling at 200,000 km/sec in opposite directions (i.e., the speed of separation) is
    (200,000 x 200,000)/[1 + (200,000x 200,000)/(300,000x 300,000)] = 276,923 km/sec which is less than 300,000 km/sec (the speed of light.) In fact, the maximum possible velocity of separation would be 300,000 km/sec.

    So, from the Earth’s perspective, 13×10^9 lightyears which would take light 13×10^9 years to travel represents only 13X10^9 light years across from one of the universe end to the other with the earth in the middle and it would still be 13×10^9 lightyears from the Earth to either end.

    I don’t know how to say this but. to put it in the colloquial,

    This is weird shit!

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  • Stephen Garramone

    No such thing as a stupid question but this is still weird, to me. My brain is too limited.

  • TheRafman

    I like topics like these, it pushes our minds to the extreme.
    There is something here that does not compute: either the age of the universe is much older or the galaxies that we think are 47 Billion light year away are much closer (some kind of distortion in between is causing the discrepancies perhaps?).
    If the age of the universe is 13 Billion light years and let us say it was expanding at the constant speed of light (which is not) then similar to the example of my previous post where if the two objects where going in opposite directions at 300,000 km/sec, relative to each other, A and B would be traveling at the sum of their speed: 600,000 km/sec (forget Lorentz for a moment); however they would never be able to see each other while traveling at that speed because the sum is greater than the speed of light; my point is if the universe is 13 billions years old and matter was still traveling at the maximum velocity, the speed of light since the big bang, from opposite end A and B would appear to be 26 billion light years away (although they would not be able to see each other).
    Also if the rate of expansion of the universe is currently increasing, it should never surpass the speed of light according to Einstein’s theory; there is no way we should be able to see galaxies as far as we think they are while the universe is smaller than the straight line distance between us and the this particular galaxy, so either the age of the universe is much older or the galaxies that we think are 47 Billion light year away are much closer.
    I am going to sleep, good night.

  • Stephen Garramone

    To The Rafman -

    See… it wore you out, too. Lorentz et al are conjectures but so far these hypotheses have been borne out by what limited experimental evidence we have. The slowing of time at high speeds using atomic clocks on GPS satellites, for example.

    Is it conceivable that we can have three points in space (L, C, R) and all be equidistant apart and yet opposite from the central point (C)? Yes – on a sphere. In this case CL = CR = LR. BUT, to get from L to R under this paradigm one does not have to go through C, that there is a more direct route across the two dimensions which bypasses C (the common starting point.) This involves going out of the two dimensions into a third dimension, where C does not exist and going directly.

    To analogize, in three dimensions, this could be possible that we jump across of fourth dimension to achive the same thing. Take a hypothetical beginning point in 3D whhere space “explodes” as is postulated by the Big Bang and imagine 3 objects traveling out from the center but remaining equidistant apart and with the center -that’s a tetrahedron with the sphere circumventing all four points (the three new points plus the center. Each point can access the other three without going through a common central point yet everything be equidistant apart. That would require a four dimensional “sphere” x^2 + y^2 + z^2 + w^2 = r^2. Lorentz thinks that “w” is time and there are a multitude of equations bringing time into play which imply such a fourth dimensional universe. Yet, we can travel back and fourth against three dimensions but not time, so what gives?
    Again, this is beyond my pay grade and I agree with The The Rafman – it is time to “go to bed.”

    So as Edward R. Murrow use to say, “Good Night and Good Luck.”

  • TheRafMan

    Stephen,

    Just because we don’t know how to travel back and forth in time it does not necessarily mean it is not possible, after all we don’t want to be like the ones that claimed that the earth is flat and at the center of the universe.
    You make a very good point that we seem to forget rather quickly: ”Lorentz et al are conjectures but so far these hypotheses have been borne out by what limited experimental evidence we have.” … and that includes Mr. Einstein, bless his soul.

  • Stephen Garramone

    No argument…

    Einstein sure was a genius with his application of the Lorentz equations and General Relativity proven in May 1919 or was it 1923 (with the total eclipse of the sun and the changing of position of stars behind the sun?)

    I don’t think the world is flat… my brain may be, but not the world.

    Looks like the universe is 39 billion light years around. Why?, Because it takes 13 billion light years to reach the furthest point, so far, and by Lorentz, if he and Einstein were right, is 13 billion light years from a point on the opposite side – making a perfect circle with the three points being equidistant from each other all 13 billion light years away from each other.

    What a concept…

  • http://jlj123@shaw.ca james jackman

    Brand New newcomer:

    for some reason this question has been bugging me. am very uneducated in this area, but,

    is there any information about the universe ever having slowed down in the past(?) and re-started?

    in any explosion there are several phases:why could not the ‘big bang’ have the same pattern?

    hope I don’t sound goofy.

  • phil

    Look I am as thick as they come, but how the heck do we come to a figure of 13.7 billion years old for the Universe. It seems to me that everything and I mean everything is either round or formed from round elements and even the elements are formed from round atoms and even the atoms are formed from round, do you get the picture? So if everything is round and the Universe is expanding at an ever increasing rate all you can see to get the 13.7 billion lifespan is a linear observation or have we learned a way to go back 13.7 billion years and then bend time so as to observe around the horizon? It just doesn’t make sense! Clever these scientists unfortunately I think outside the box and do not accept conventional mathematics.

  • Jock

    The problem with trying to explain this stuff to Americans is first getting them to understand that they are not the center of the universe!

    • noveds

      Even we Americans, and I’m going on a limb that you mean US citizens, understand that our nationality means nothing when compared to 14 billion years.

  • Skeptic

    The most interesting thing is the universe is expanding only when there is no star involved because stars have gravity on each other. So, we have this singularity that exploded into “47 billion light years” wide in 13 billion years all because of the “expanding space.” Galaxies are moving away from each other, but the stars in them are not. If the big bang theory is to hold, there was a time when galaxies were close to each other like stars are today, but that didn’t prevent them from moving away from each other.

  • peter cross

    is it possibly that the author here has underestimated the actual point being referenced by some of his critics. perhaps what some of the emails meant was “if the universe has a diameter of 2×46.5 billion light and has been flying away for 13.5 billions years. then the average speed of two furthest points is faster than the speed of light”. such a situation would indeed contradict special relativity, but doesn’t because of a loop hole in relativity. the answer is that the matter of the universe isn’t merely moving apart, the space it’s self is being stretched. einsteins theory refers to movement through “space” as being limited. while space it’s self can be stretched, warped or even punctured without causing any violation to the theory.

  • peter cross

    .. relative to matter the two furthest points of the universe are in fact travelling faster than the speed of light. some readers may be surprised to hear this but photons have already traveled, faster than the speed of light in a number of experiments.

  • Andrew Thurlow

    If red shifting allows us to calculate that the universe is 13.5 billion years old. Are we not concluding the age based on our light horizon.

    If we can only see 13.5 Billion years spherical radius (trying not to think 2D or even 3D at this point (of course time becomes a factor as well) from our current position, and the universe has since stretched beyond that to 47 Billion Light years. How do we know what our relative position or distance from the center of the bang is?

    Is the bang itself within our light horizon? What about an observer that therotecially exists at the edge of our light horizon, who can see 13.5 Billion years further “out” or “in” than we can

    Forgive me if this seems like a primitive thought pattern, its very tough for someone with standard TV documentary understanding to grasp such fundamentals of magnitude… its like asking a Computer program to contemplate the existance of the VIC-20 that its running inside of…. but I’m working on it!!

  • Andrew Thurlow

    Now,

    At the risk of making the head of everybody who has an IQ less than 139 explode. I propose that:-

    Space travels faster than light, thats why you can’t see it, thats why its black, because it doesn’t emit any light.

    Light is a by-product, an “effect” an “emission” so is space in fact (preceded only by the bang that unleashed it.. or the function call in the computer that ran it). Space is less dense than light and of lower mass.

    Black Holes are so dense they trap light, but they only BEND space (or Space-Time) they don’t trap it. poor Light, its obsolete, slow and antiquated. Look at it from a Universal Scale, how slow is light compared to the magnitude and distances we know exist based only on what we can see. Space is a lot bigger than the range of light (even from teh POV of the Big Bang) by a lot, I don’t mean Billions of Light Years, I mean googleplexes of Light Years.

    Space is the speed limit o fthe universe, you cannot exceed the speed of space, you cannot overtake space. the real size of the universe is where the edge of space is..

    Now theres a hypothesis for the scientists… go prove it… I expect results on my desk in the morning 8-).

    • Anon

      What the hell Andrew?

  • Linro

    Ok. I have no idea on space or whatever. But the arguement here is that we are not able to see things that are furthest away from us (47 billion light years). I believe that is true. Since the universe is expanding and the fact that not all light forming stars were created right after the big bang. Therefore this gap between the furthest star or galaxy and the time it formed makes us unable to see them. So i assume that we are blind to approximately half a billion light years of stuff. Sorry if what i wrote is rubbish.

  • http://www.diacad.com David Ecklein

    Now that I think about it, there may be a simple way to answer this paradox. Those who cannot believe Hubble saw a galaxy 47 light-years away because the universe is only 13.5 billion years old are right in a sense. Hubble does not see such a galaxy as it is today, but only as it was when light left it long ago. Meanwhile, it has been moving away from us, due to the expansion of the universe. Light from such a galaxy would have to take less time to get here than 47 billion years, so we are looking at the past, not the present. To speak of a simultaneous “present” has no real physical meaning on this scale of observation.

  • Andrew Thurlow

    After evaluating and re-evaluating and re-evaluating what I have read, including my own comments I think I finally get the picture, if not then this is where I reach my own impass.

    I see 2 alternatives from the way I currently understand the discussion, and I think the second is correct (if either of them is). If neither of them is well then I’m going to need a sedative to switch my brain off.

    1) If all light, energy, time, matter etc all starts on its journey from a singular point, and the outer edge of the Universe is expanding (increasing the distance light has to travel to catch up). Then it must be moving faster than light. If Light is running the hundred meters at full speed and the finish line is getting further away, then it would seem logical that the finish line is moving faster than light (or the universe is expanding faster than light)….. unless (and this is what I think Tony & Steve are trying to say) as part of the expansion and stretching of space light is…

    2) ….stretching with it as Steve suggests, getting pulled along with it (kind of like running on a treadmill… thats on the back of a moving truck). Does this mean in this case Light has actually travelled the 46.7 Billion Light Years (spherical radius), by ownly making 13.7 Billion Years of effort. Scenario 2 is the only way I can see it occuring without violating the speed of lights limit.

    But what of Particle Physics? What about quantum particles that are supposed to exceed the speed of light (and in fact cannot go slower than light). How do they fit in, or is this just unproven conjecture

    Also if the expansion of the universe is accelerating (as per Hubbles constant), then wouldn’t it eventually expand at the speed of light also, and once it reaches that speed it couldn’t go any faster. This would mean it could only either remain at a constant speed of growth (Light Speed) or slow down (if something interupts its inertia and pulls it back in)

    How am I doing?

  • arnold

    Agreed that universe is expanding, but the distance to the farthest object cannot be the age of the universe.

    The distance to the farthest object can be 45 (whatever) billion light years- although the age established is only 14 (whatever) billion light years.

    Think of the center of the universe as the center of the earth- the radius is only 6400 km- we live only on the surface of the earth- distance between any two points can be as much as 12000 km.

    Thus 45 billion light years can be the distance between individual stars- but cannot compare it with age of universe.

    Universe is still expanding- will expand to a level- then contract to big crunch- only for another big bang- we will still be discussing same question after another 100 billion light years.

  • arnold

    Further to my previous comment-

    The age of universe is 13.75 billion years (time) – not 13.75 billion light years (distance).

    Hence the initial question although deserves merit- is irrelevant.

    Cheers
    AB

  • Andrew Thurlow

    I’ve made a breakthrough…. I have decided that the Universe is not yet expanding at the speed of light (or indeed faster than it). The following thought process led me to this conclusion (it assumes that somethings are actually blue shifting from our relative POV).

    If the Universe expands forever…..

    Our Light Horizon is said to be 13.5 Billion Light Years in Spherical Radius.

    If an object NOW was PHYSICALLY 13.5 Billion Light Years away from us (eg a Galaxy for the sake of argument). The object would be at the edge of hour light horizon and as the Universe continues to expand at an accelerating rate it would very quickly cross the point at which light emitted from the Galaxy would never reach us. The last light it emits before it crosses the horizon would take 13.5 Billion Years to reach us if it happened NOW.

    However our visibility of it NOW (at the same time it is is crossing the horizon) would be how it was 13.5 Billion years ago. If we continued to watch the galaxy for 13.5 Billion years longer from our POV we would suddenly see it disappear (it would quite literally wink out).

    Applying this Logic….

    Assuming the Universe continued to survive and expand for a long enough duration (ever accelerating as it does so – possibly until it expands at the speed of light). Also assuming that the Earth would also be around to see (which it wouldn’t because our Sun would be long dead – but say we left a camera in its place to continue watching). Also assuming that anyone is still around to care.. and that the Universe hasn’t actually crunched and keeps expanding. Eventually everything would wink out completely because the inflating universe ballooning concept of everything red shifting away from us would cause everything around us to eventually move more than 13.5 Billion Light Years away. The sky would become completely dark (not all at once of course and only after the closest galaxy to us had finally crossed the horizon after who knows how many billions and billions of years). In fact the only stars we would see would be our own Galaxy (again assuming it maintains its own harmonious equilibrium of rotation around whatever is at the centre for all this time)

    If The Universe does a Big Crunch (or expands to a static size)

    If one day we look at objects that are currently redshifting now, and they neither show a red or a blue shift, then the Universe has stopped expanding and there position away from us remains constant or static, if those same objects then show a blue shift (NOTE: There would be countless Billions of years between each phase), then the Universe would be starting to Crunch.

    If the Ballooning expansion of the Universe theory is correct, then how can anything be blueshifting at all. If everything further out from the Big Bang is moving away from us (red shifting) then we are also moving away from everything further behind us. Ultimately if everything is moving away from everything else, the the doppler can never be blue.

    If an Ambulance is coming towards me, then the doppler is blue, more so if I’m moving towards it as well. If the Ambulance is moving away it would red shift, more the further away it gets, until it passes beyond my audio horizon. If the Ambulance is following me but my distance from it is ever increasing as the universe expands, then the doppler coming towards me….

    AHAH!!!! have I just answered my own question….If the Light is coming towards me faster than I’m moving away it would still be blue shifted, if I stopped then the light shift would be more blue shifted as it would then get to me quicker.

    Okay so I can see why MOST things are red shifted, but not everything…. Unless I was moving away at an expansion rate faster than Light only then would everything be red shifted. This is supporting evidence that Space-Time is not expanding faster than the speed of light (at least not yet).

    I think I just made an important link in grasping this, I’m excited!!!

    If anybody is still reading this, please desk check my logic!!!!

  • arnold

    Nice thoughts Andrew!

    The age of the Universe is about 13.7 billion years. Nothing travels faster than light, but it is a misconception that the radius of the observable universe must therefore amount to only 13.7 billion light-years. This reasoning makes sense only if the Universe is the flat spacetime of special relativity; in the real Universe, spacetime is highly curved on cosmological scales, which means that 3-space (which is roughly flat) is expanding, as evidenced by Hubble’s law. Distances obtained as the speed of light multiplied by a cosmological time interval have no direct physical significance.

    To add, just as need a speed equal to escape velocity to leave earth’s gravitational field- do we have a concept of escape velocity to leave the 47 billion light year diameter universe.
    Your inputs are welcome.

    • Andrew

      8-)

      Now let me get this straight., The universe today is bigger than it was yesterday (or even further back). So looking at the same fixed point… say a Galaxy 13.7 billion light years way), while the light is travelling from the fixed point to us, the universe is also expanding, so it might actually take longer to reach us as it is running on a tread mill at a fixed velicity but the treadmill is getting faster, which means “relatively speaking” light gets slower as it travels further even though it travels at the same speed (of light). I can see how this would effect both the actual size, and observable size of the universe, and why it has time to expand beyond the range of light “when considered from the relative perspective of light”.

      Could this mean that the escape velocity of the universe is not possible to be achieved, because the universe will always be larger than the maximum velocity of light so you could never reach the edge to escape (unless the universe stops expanding or begins to crunch).

      Then there is the other question, if you could reach the escape velocity of the universe, escape to where? What happens if you cross the event horizon of the universe.

      I believe I’m beginning to understand the concept of the “event horizon’ and “Time dilation” a little better. The edge of the universe is simply an event horizon, as we get ever further away from the ground zero “event” of the big bang, so the edge of the universe gets further away from us. It would be similar to being caught in the event horizon of a black hole, you can never achieve escape velocity, not even if you are light, because of “Time Dilation”.

      Physically the universe could exist as a near flat plane, but surely only if there is something at the center to cause an axis to be created (eg a nucleus of immense gravitational force (enough to eventually pull black holes back in, and eventually crunch teh universe). This would be acceptable based on what we know of Planets revolve around suns, Suns revolve arround Galactic Centres, so it could be feasible that Galaxies are all revolving around the central core of the universe, which would cause the universe to exist as a “plane” with some level of depth or thickness, but essentially a flat disc like a galaxy)

      It would aslo mean that all the visible universe (including us) as well as the non visible universe of stars and galaxies outside our perception (all Matter and/ or dark matter) would all be on that outer event horizon (as it is all on the surface of the ever expanding surface or “crust” (spherical balloon – that inflates from the centre, or expands because of vacuuum, whichever way you want top look at it).

      Everything back from the crust to ground zero would be empty space-time, even devoid of light as all the light has long since travelled past the source, but has not yet caught up or overtaken us as we can always stay ahead of it due to the inflation of the universe. The things we see as observable now are mostly due to the light, that travels with us, that has travelled with us since the dawn of time because it can reach us from its emission point.

      Only took 2 years to reply, not a bad effort!, I’m losing focus so I’ll stop now.

  • karl

    is there anyway to look so far into space you can see the big bang,might be a a stupid question but just wondered.

  • prabha

    we are talking abt billion s of light years and still see the same stars that we saw through naked eyes nothing beyond its a waste of time and effort ,, its too late for our generation to see what the edge of universe looks like . need to put a 1000 times bigger than hubble kind of telescope . so we should be talking about 1300 billion light years and so on ..

  • http://news.com.au Jordan

    Noone on this planet can answer these questions,soo stop wasting you time with these silly numbers,

    • Andrew

      8-)

      Hence my earlier comment, its like a a byte of computer data, trying to comprehend the VIC-20 that it exists inside of.

      One single brain cannot compute the whole picture. But Network them!!!!

  • partha

    is there an absolute distance “end pont to end point” of Universe?

    if so how much in terms of light years

    Mind tries to calculate a number?
    Heart says- stop it!

    Conciousness prevails- & says…….you can’t.
    Subconcious mind says-it’s 4 dimensional wrt to time- God ….as Church would insist on! Scientists would dwell betwwen Neils Bohr….Enstein, Hubble, Hawkins and rest!

    Two things we will never probably percieve…. the smallest particle and the end point distance of Universe. Its not on “linear scale” its…. trans-dimensional.

    I am not sure…i can only partly concieve….when i close my eyes…close my normal instincts…my normal thought process…its an endless haze of galaxies, dark holes, expansion/contraction, ………. “n” dimension scale of distance & time , “E” factor of mass & energy intermingled….& some springled antidote of light speed constantly keeps popping up.

    Its like a matrix

    Not sure of this crazy idea

    Is it a blind man inside a dark confined room & looking for a black cat which actually does not exist!

  • PC

    How come you do not take into consideration Relativity Theory?
    Are you saying that the Galaxy was close to Us when the light came out towardes earth, but because of Universe expansion we are much further away, that why the Galaxy appears to be much futher away from us!!!
    For example The Galaxy was 1 billons years away, 1 billons years ago.
    The light that started 1 billons ago will reach us in 5 billons years!
    Whose 5 billons years is it, the Galaxy or our earth’s time?
    Scientist like other humans tends to use rules or calculation to their advantage, neglecting others.
    Shouldn’t the light from these galaxies apper “Reader”!!!
    Am I missing something?

    • Andrew

      In a nuthsell, and this is the best I can do on my 8 bit brain in a 64 bit world, among an incalculable amount of bit universe…..

      Billions of years ago, the galaxies were closer. Its kind of similar to Continental Drift, when the planet was 1 super continent, and the countries all spread out, but imagine that as that is happening the planet would also be getting larger and expanding.

      As the universe expands everything spreads out, relatively speaking its expanding faster and faster, but it is also stretching as it expands (just like the rubber on a balloon as it inflates). But then if the universe exists on a “plane” liek a solare syatem or a galaxy, then it wouldn’t be spherical but flat.

      I still tend to think of it as spherical in nature however.

      Light that started from a galaxy that is 1 billion LIGHT years away from us will reach us in a billion years (plus the amount of the amount of addiitonal time needed to traverse the additonal distance from a billion years of expansion). The stretching shouldn’t effect it as light stretches with it (the wavelength of teh light stretches from visible light to Infrared (this is how the red shift occurs).

      When Space strectches, that which it is carrying also stretches (and warps), this is where Time Dilation, Event Horizons, Mass and Gravity wells play apart in allwoing the universe to be physically bigger in size, than what is possible for light to travel in that time.

      In the same time it takes light to travel 13 billion years, the Universe is able to expand to 47 Billion Light Years (at leats, that is what is observable) , because 34 Billion Light years of inflation has occured while the light has been travelling which has stretched the light as well. Effectively the light has travelled 47 Billion Light years, with 13.7 billion light years of effort, because of the “piggy back”.

      Get an accountant to expalin “Inflation” to you, the concept is similar. Basically you by a house for $250,000, you pay $700,000 by the time the mortgae is over in 20 years, you sell it for 1,000,000 after 30 years, you have made $300,000 wow, lot of money, but inflation means that 30 years later it now costs 1,300,000 to by the average house, so no profit. This is why the banks suck, and funadementally why the the universe sucks, I funamentally believe tha the universe expands because all that vacuum means it sucks, and its being sucked outwards.

      ;-), but thats just my relative POV today. May change tomorrow, I’m usually more optimistic at the start of the day, and as I get tired, my reality warps, and my perspective changes, but that just demonstrates the nature of relativity.

  • Peter Morris

    I still don’t get it :-)

    If the universe has been expanding at less than the speed of light for 13.7 years then how can it span further than 27.4 light years?

  • The Expert

    Guys u dont hav to be so complicated about the size of the universe.
    We cant tell the size or age, because 13.7 billion light years is the farthest we
    can see! So no matter how advanced technology we get, we cant see farther
    than 13.7 billion light years, because the light hasn’t reached us yet!

  • grady deed

    This is a mind warping topic. For those in the know, werent we all close together 13 billion light years ago? and if so, shouldnt the light from 13billion years ago at least give a false location?

  • EternalSkeptic

    I hope my intervention here is pertinent, as I have a question.

    Now, I do not dispute the information provided in the video and the essay posted here, but it is my understanding that the hubble telescope, as it took these pictures, was orbiting the earth, correct?

    My question is this: If the telescope indeed captured images which are 47 billion light years away, how does it logically follow that the radius of the Universe is an equal 47 billion light years?

    Does this not imply the premise that the earth is at the center of the Universe? I thought we’d already concluded this was not quite the case…

    • Samuel

      Hey EternalSkeptic,

      I’m aware that this was posted a year ago but i thought i might give it a shot anyways. Actually, where you are sitting right now is where the big bang occurred. Everywhere is where the big bang occurred. Following the same train of thought, your living room is the center of the universe. If the universe is bent in upon itself like some posit, then everywhere is the center of the universe. Hope this helps.

  • Ravi

    If everything is expanding in other words if everything is moving away from everything else then why the distance between Sun and Earth remain same OR why Galaxies are colliding, There is a theory that Andromeda and Milk way will collide after some billions/millions of years, I think there are some conflicting theories

  • Tom

    cool m8

  • vlooi

    our galaxy comes from past like the first galaxy we can see, why can we see them but not our own or do we see only galaxys that shoot to the opposite diracton of us

    • Andrew

      Hi vlooi,

      we can see our own Galaxy, but only from inside it. Its like asking why can’t you see the outsie of your house when you are sittying in the living room. If you mount a camera across the street, you will be able too.

      We cannot look back at earlier light from our own galaxy, unless we are far enough away from it to observe the light that has already been emitted from it.

      As we are local to our own galaxy we can only see light from our nearby stars. When you look up at the night sky (if you travel far enough into the countryside, way from the lights). You will indeed see our galaxy, as a vast and densely populated field of stars, in a thick band. This is the Milky way looking towards the centre of the Galaxy.

      City lights, street lights, and the moon all interfere with the visibility of it under normal suburban circumstances, which is why you only see the brightest stars and planets on most given nights. This is known as “Glare” in true darkness of night, out in the sticks, you can see the splendour of the milky way. It is why most telescope observatories, are miles away from anywhere.

    • Andrew

      So you can only see back as far as the distance an object in teh sky is away from you.

      Stars in our Galaxy are relatively close, so those we can see as wee look inwards towards the centre (as well as the few we can see when we look outwards that are very local to us) are between 5 LY to 100,000 Light years away. So the furthest we can see into history in our own galaxy is about 100,000 years.

  • Naasson

    Question: In order for light to travel, doesn’t that light need a SOURCE in order to continue traveling? How can it continue traveling without some ongoing source to keep it illumintated? Or is this all just theoretical talk? I mean, it makes sense when applied practically, like turning on a flashlight for instance, but talking about some ongoing ‘traveling light’ hardly seems plausible.

    • kody

      a flashlight dims around 10 feet rather than being bright enough to see 47 billion light years away. it took light thousands of years to get her so it will take longer for it to go away now since the universe is expanding

    • bruce

      Naasson asked about the light source. Light moves away from its source much like water from a hose. Even when the hose is turned off the water already on its way continues until it hits something. So when we shine a flashlight (or torch) up into the sky for a second it creates a slug of light that travels alond, spreading out and is only 1 light-second in length.

    • Andrew

      Hi Naasson,

      Once an object has emitted light, the light that has already been emitted will keep travelling until is absorbed.

      If I turn on a light in my house, it continues to emitt light in all directions while it is turned on. If I turn it off it stops emitting light, but light that has already been emitted is still “airborne”. Practically speaking the distance between you and the light is so close that it seems near instantaneous”. In reality it is like waching a supersonic jet plane fly past, you see it fly past, and then you hear it. Same with lightning, yo see it, then you hear the thunder.

      With light, it is similar, if the sun exploded now, right this second, you wouldn’t know about it for 8 minutes. The reason is Light already emitted from the sun 8 minutes ago, is only just reaching us now. In realtime the sun is 8 minutes in the future from our “relative” perspective. Even though the sun dies, teh light already emitted is still travelling.

      A simple example is, you just left the city (sun) in your car (light). You have a 10 kms to travel to get to me (earth). Then 2 minutes into your journey, the city gets destroyed, but you don’t. Some 6 minutes later, you rock up and say how lovely it is in the city, nice and calm, unaware until another car arrives 2 minutes after you filled with screaming people fleeing in panic.

      8-)

    • Andrew

      The flashlight dims at 10 feet, because the photons spread out as they move further away from the source. Similar to what happens to the Universe as it moves further way from the source, the light stretches however as the universe does.

      This is another factor in why some objects may not be visible, because their light intensity might not reach as far, so only a small amount of light reaches us, or something might be in the way, that light can’t penetrate.

      This is why lasers are more intense, because the photons are more focused so they don’t disperse so easilly.

    • tom

      What does the size of the universe mean exactly? Does it mean there are objects within that area? Then if the universe is bigger than 27 billion light years across because of the fact that space can expand faster than the speed of light – how did objects get beyond the 13.5 billion lights years in distance from wherever the big bang occurred since we know that they couldnt have traveled faster than the speed of light? Can objects move in distance by the mere fact that the space they are in is expanding? What does that mean?

  • Gaurav Bhagat

    I don’t understand one thing that why no one thinks that if we see something 47 billion light years away then we are seeing something what it was in distant past. That galaxy will not be there anymore… in the time it took the light to be visible from here the galaxy might have gone further far even more than 94 billion light years away as the moving away speed is accelerating… Or I am missing something here?

    • Andrew

      No, you are not missing something, and it is a phenomenon that does make it difficult to compute the reality of the universe.

      It is indeed entirely possible that what we see may not exist. In fact the further away it is, the more likely that it doesn’t (or at the very leat it would look very different to how we see it now).

      It is also valid, that there is a limit to what we can see due to the expansion of the universe, that object may exist that we will never see, because they are too far away for the light to ever reach us.

      It is for this reason, that relativity is so important. It teaches us that “relatity itself is relative, and really there is no such thing as a true definable reality”, as it is different for everyone and everything depending on the circumstances, and the relation of one thing, to everything else.

      Consider this, when you empty the bath or flush the toilet, most people are aware that in the the northen hemisphere the water spins down the drain in the opposite direction to the southern hemisphere. This is called teh coriolis effect. It demonstrates however, the illusion of reality. It is actually spinning in the same direction. The relative position of the observer changes, in the northern hemisphere the observer is looking at it from on “side” and in teh southern, the observer from the other”. Its like one person standing in front of a transparent clock, and the other standing behind it.

      Clockwise to observer 1, is anti-clockwise to observer 2. This demonstrates the illusion of reality. Realising such things, helps break down an unlearn what we have learned helping us understand “Relativity” and to see the universe in a relative way. However this too is just another interpretation of relativity. So relativity must also be relative.

      This very comment is relative, as its based on the ay I see things, and currently interpret them.

  • coys

    how dumb does the writer of the article feel knowing now that there is something that moves faster then the speed of light.

  • Ralpy

    They say that when the big bang happened that it expanded faster than the speed of light but how is that when nothing is faster then the speed of light. That would mean if say we were there during the big bang it would expand past us in a billionth of a second and we would never see it coming. I wish i was smart enough to understand all of this cause its a passion that i have but this just seems really confusing. Im also repeating all of this from how the universe works and Dr. Michio Kaku is the one who said it.

  • Chris J Sayers

    If what we are seeing from the edge of the Univers is 14 billion years old, #1 What does it look like today. ???
    #2 How do we know that the big crunch has not already started. ???

    • AL

      there is no more big crunch since they discovered that the expansion of the universe is accelerating, hence, dark energy and dark matter

  • ryan

    I have a few questions about this whole universe thing:

    how do you look at light that is millions of years old and deduce that the universe is currently expanding? yeah acceleration doesn’t cut it seeing as it’s all in a very distant past. Is the fact that there are blue shifted galaxies not a problem for anyone? and what does Andromeda tell you? does that not negate Hubble’s law? dark matter and dark energy we have not discovered? that’s the theories proof? uniform radiation that isn’t uniform? why do all Galaxies center’s appear extremely bright from any angle viewed but there is nothing bright for us to see in our own because there is dust n the way? really? with so much dust we must not be able to see anything on the opposite side of our galaxy hey? would Entropy not need an external source of energy applied on the system for the system to be able to form order? will this extra energy applied from externally not have to be more than the effects of the energy? So there should be extra radiation that cannot account for the internal order of the universe. this radiation should also not be uniform as it would be more intense where applied. if this force as entropy suggests is outside of the universe then this force will be eternal as well as super natural? please if my science is wrong please help me! think i’m finding religion

  • Hugh fuve

    If space time is elastic, and compresses within black holes. Then why wouldn’t all matter cause compression and shrinking, everywhere? Even a single atom could contribute to total universe contraction from its point in space time. How would we know the difference between everything shrinking and everything expanding away from each other?
    If everything is shrinking then you don’t need a big bang, you just need matter to come into existence somehow at any place and anywhere; say just basic hydrogen atoms which become more complex in stars and are created in the gaps where space time rips near black holes. The universe now can be in constant collapse, infinitely larger and older than we can imagine, we just observe the rest of the universe as low frequency radiation, as if we are inside a black hole and looking out, where Time slows around us and we can only see as far as the event horizon. Isn’t it just a little bit suspect that we appear to be at the center of the universe? With red shift in all directions? Everything being in collapse makes more sense doesn’t it? How can we prove/disprove this?

  • http://www.facebook.com/people/Keith-Stafford/844132267 Keith Stafford

    Thanks for this explanation. It boiled it down to fairly common-sense language for me.

    I had seen a posting at the Facebook group “I fucking love science”, which I subscribe to, where the poster laid out the 47 billion light-year size claim. And from my initial knowledge, I posted some comments about how they were wrong and even backed it up with some weblinks to NASA and Harvard’s Center for Astrophysics. Turns out I was wrong

    But this cleared it up. The way I see it in my mind is imagine 2 cars out on an Interstate highway. Both initially 50 miles apart. The lead one going west goes 50 mph (our galaxy) while the trailing car does 60 mph (the speed of light). The trail car will eventually overtake the lead car, but when it does the total distance covered will be well over 50 miles.

    Thanks again

  • James Jenkins

    The measurement was made using the collection of photons on the hubble lens over an 11 day period (I believe). The result was a collection of photons which originated from the source, estimated at approx 47 billion light years away at the time of origination.

    Regardless of the expansion of the universe (which would imply the galaxies which emitted the collected photons are further away now, if still in existence), you can not escape the fact that the hubble collected photons from a source that was apparently about 47 billion light years away from where we are now.

    I have yet to see a logical response that directly addresses the apparent 47 billion year old photons, assuming the speed limit for photons is near the speed of light, which if anything, is overestimated due to the slowing effect light experiences when it encounters particles, of which space is not totally void. It seems to me that many are focusing incorrectly on the theoretic positions of these galaxies and avoid this issue regarding the age of the collected photons. Can anyone explain to me how the time span of the photons apparent journey could possibly be less than the natural limitations on the speed of photons?

  • Topik

    What is the distance traveled by Light from 46.5 Billion Light years of the expanded universe?
    and the formula to compute for distance of light

  • Nico

    Big problem. “Everything in the entire universe is flying away from each other at a rate linearly proportional to its distance.”
    No it is not. Why then do you get galaxies crashing into each other? Why then do they calculate that Andromeda will crash into the Milky way in the future?
    Why do people always state things like the above when it is not true???

  • Steve G

    Hey, I like that…

  • lee

    bloodly oath

  • Greg

    For critical thought: Say we are looking east at A1689-zD1 and realize it is that far away. Then say we are standing on A1689-zD1. If we look up are we surrounded by star fields? If we look to the east will we see photons of remnants of the past equally as far away? I know if we look west we should see us, but what about looking east or south or north? Greg

  • Andrew Thurlow

    Hi Peter,

    I was just watching a History Channel documentary that suggested that the galaxies furthest away “with the greatest red shift” where actually moving away faster than the speed of light, this would indicate that at some point in the future they would cease to be visible (and might have already passed our light horizon, but we wouldn’t know about it for another 13.5 Billion years.

    It also pointed out that due to this fact, it was space itself that was travelling faster than the speed of light as it strecthes, indicating that space can exceed the speed of light, but the matter within it was simply being carried along while it continued to move at its regular speed of light.

    This begs the question, we may be moving fairly slowly around our sun, and our sun fairly slowly around our galaxy, but our whole galaxy could be getting carried along faster than the speed of light by space itself without us even realising it (especially relative to objects that we are red shifting away from).

    What do you make of that, if anything?

  • Andrew Thurlow

    Hehe

    It is understandable for the average joe to get confused between years and light years.

    I have to constantly remind myself that
    1 Light year = approx 5,865,696,000,000 (Miles)
    and that this is the DISTANCE Light TRAVELS in a year.

    The age it of light that travels said distance is 1 year. This tends to make the Distance Light Travels in Light Years also equate to the Age (as 13.5 Billion YEARS spent travelling also equates to 13.5 Billion LIGHT YEARS distance

    It is then reasonable (if not confusing) that Light year is just as valid as measuremnt of time (or age) as well as distance. What it doesn’t allow for is that not everything in the Universe is visible, and that just becasue light hasn’t had enough time to travel that far, it doesn’t mean that space hasn’t had that much time.

    I can understand how the Universe might be a greater size (than 13.5 billion Light Years) and age (of 13.5 Billion years) based on the stretching of space beyond the range of light (if space at the extreme red shift is actually stretching faster than light).

    I can also understand that the Universe could be 47 Billion light Years in Diameter, but everything further than 13.5 billion years would in fact NOT be visible, including the big bang itself (unless we were closer than 13.5 Billion light years to it (which would make us very young compared to the highly redshifted areas), but… whats the circumference, and the area of the sphere heheh 8-)

    If Red shifting calculates the Universe as approx 13.5 Billion years old, indicating that Light has only had enough time to travel for that long, As such we apparently cannot see further than than 13.5 Billion Years, I can accept that, and also understand that it does not imply that this means the universe is only 13.5 Billion Light Years in size, in fact if the maximum range of our visibility is 13.5 Billion years (Our Light Horizon), then the minimum size of the universe must be 27 Billion Light Years diameter (thats assuming it stops at the limit of our visual perception, and that we are at the center).

    As we are not at the center, but the big bang is, then it could be a lot greater in size.

    The bit I wan’t to know is:-

    What is our relative distance from the Big Bang, as the Universe must be at least 13.5 Billion Light Years in Spherical Radius Wider than that figure, assuming it stops at our furthermost red shifted visible distance (which it would be foolish to think that it does).

    In My (limited flat brained opinion). Similar to Lightning and Sound.

    The Bang preceded the existnace of light. Space is the Medium in which all matter (and things not of Matter exist).

    Pressure and Enery came first and built up to a point of realease
    Then the medium blew forth (Space)
    Then there wasa flash of light (emitted from the bang) which means the bang happened prior to the light (meaning that light is an event horizon)
    Then came the matter (some of it emitting light itself.. galaxies etc)

    If light came after space, then space is ahead of light, it doesn’t mean its travelling faster (although it probably is because it would be of lesser mass than light), it just has a head start, and thus the medium is greater than the percevied size.

    Now pick this apart and tell me how average a Joe I am

    8-)

  • Andrew

    Yes Linro,

    I think along the line that you are. The big bang prededed space, and space preceded light.

    So at the very least space has a head start, light can only travel so fast, and space is “ballooning faster than it”. Even if its ballooning at the same speed as light (to satisfy light limit of the universe die hards). Light can never close the gap. This makes it possible for space to be of a greater size than the distance light has travelled from the big bang.

    As for the distance we can see, well that comes down to how far the object is away combined with how far light can travel since the light at the source began emitting, as well as how fast we are moving away from it, or it away from us.

    Now here is another head rattler. If we can see an object that is X number of light years away, then it is X number of years old what we are seeing. If we have a hypothetical Galaxy that is 13 billion light years away and is visible in the sky tonight, how do we know its still there. If its in the sky tonight, but not tomorrow then we would know that it ceased to exist 13 Billion years ago. Does that get taken into account when we work out the size of the universe.

    In fact the Universe might be smaller than we think, the further out you look, the more likely that the area no longer exists, and we are seeing an echo… a ripple if you like. Clearly what you see is not what you get!!!

    I know that there are simulations that extrapolate positions of galaxies, based on the motion observed so far, but there could be many variables. The visible universe could be an illusion. Just like if our sun was to explode now, we wouldn’t know about it for 8 minutes, how do we know that the universe isn’t already collapsing, and we just can’t see it yet (it still looks like its expanding from our point of view). On the other hand, how do we know the big bang isn’t still spewing forth stellar material, if the centre of the universe is beyond our visible range of light.

    regards
    Andrew

  • Andrew Thurlow

    It would be 13 Billion Years Old but 47 Billion Light Years wide.

    That doesn’t mean Light has travelled 47 Billion years, it is simply stating it as measurement of distance (using the Light Year as a measurement).

    In laymen’s terms it would make more sense stated:-

    The Universe is 47 Billion multipled by 5,865,696,000,000 miles in diameter), but it is only 13.5 Billion Years old because light has only had time to travel 13.5 Billion multipled by 5,865,696,000,000 miles from the big bang. NOTE: That is light emitted from the central bang point.

    That doesn’t mean the other 33.5 Billion Light Years of Space is devoid of light just because light from the center hasn’t reached it yet. There are other sources of light other than the big bang for light to travel from.

    Every star and galaxy emits light, some are closer to the bang some are further away, light shines in all directions. A Galaxy at the edge of the 47 Billion Light Year Universe would also transmit light back towards the center.

    8-)

  • Andrew Thurlow

    Hehe,

    Its even simpler than that.

    How can a city be 47km wide when its only 13 months old. It would take some rapid construction to achieve in such a time frame. But if 8 Billion people all built a house each (with the right training and tools). It demonstrates that its not impossible. The age of something does not relate to the size (something hinted at in earlier posts)

    It depends on how fast you build it.

    This whole discussion revolves around the simple question (Which is the real question that is being asked at the start of the topic):-

    Is it possible for something to exist that is larger than the distance light could travel if it was all created from the same point simultaneously, and nothing can exceed the speed of light?

    This is what the author is really asking. If The Universe was created and Light has only managed to travel 13.5 Billion Light Years (making the Universe 13.5 Billion Years old), how is it possible for The Universe to be bigger than that (47 Billion Light Years).

    The original question was confused between Light Year as Age instead of Distance. However the question still has merit.

    Its for that reason that stretching and distortion of space seems to be the accepted answer. That Space stretches, but if this was the case, light would stretch with it (or the distance between the photons would increase).

    In my opinion its because space spewed forth from the bang before light and got a head start, but also because space is the medium that light travels in. We all know what happens to light when it hits glass or water….(pencil in a jar) It bends, distorting what we perceive.

    Herein lies the key. Perception!!!. Light is a perception altering factor. As you have stated (and I agree by the way). It is an illusion and unreliible as a tool of measurement when it comes to distances so vast, because if ever increasing innacuracy, combined with distortion that can occur under intense gravitational effects. light is not immune to the laws of inertia. Its also hard to compensate for the quirks of light over such distances. This is why the mathematics becomes so important I guess.

    Even space itself may not be immune to inertial laws. In essence Space is bigger than light. Light does not occupy all of space. A single component of space has a lower mass than a single component of light, so it can potentially move faster (similar to quarks and particles). It is thought that items with lower mass than light (such as particles) do travel faster than light, in fact they can’t travel slower than light, because they will never become dense enough.

    Space is in this category, and I believe (or at least my electronic monk…albeit probably foolishly) that space is moving or expanding faster than light, and that we are being carried along with it at such speeds, but are unaware of it due to our relative position to everything else also moving in such away.

    Also on a final note to finish, Space is not a vacuum… I repeat NOT a vacuum. Sure its extremely low in pressure, because it is of such low mass and so spread out. The Phrase “Nothing can exist in a vacuum” leads me to the conclusion that space is not a vacuum because there is plenty of “stuff” existing in it. For example, Galaxies, Planets, Stars, Light, Matter etc.

    It is our understanding of space itself that is key to this discussion, not our understanding of light. Now I must go, the guys in the white suits are back to take me to my padded cell again 8-)

  • Andrew Thurlow

    Now I’m going to start debating my own comments 8-)

    I’m being so 3 Dimensional in my POV. There is more that I am starting to realise. It is clear that the common perception of the average Joe is based on the Newtonian Model of Gravity, rather than the General Theory of relativity that actually applies to such vast distances and times (as Newtonian principals are not practical on such a scale, especially when dealing with light).

    We are dealing with Space-Time, not space, we are dealing in curvature of Space-Time, not straight lines. We are dealing with Time Dilation as well as Expansion of Space-Time.

    The Balloon expansion does not cut it for me. The surface of a balloon is 2 dimensional and it is not spherical in nature. A balloon expands from one edge (not the centre). I think it is more accurate as follows:-

    Please fill the balloon with matter, and then expand all parts away from the centre. The outer surface of the balloon, ever increasing in velocity as it moves away from the center. The objects betweeen the outer surface and the center (planets, galaxies, interstellar material) etc also moving away from the center (at varying velocities depending on their distance from the center) and also away from each other. Now add Time Dilation. Closer to the center the passage of time occurs at a different relative speed to that at the outer edge. Matter is closer together at the center, and space is more concentrated (less stretched). An atomic clock at the center and an atomic clock at the outer edge would tick over at vastly different rates, as one would expect greater gravitational forces nearer the center.

    As space expands the gravitational field effecting it is less at the outer edge (most likely ever reducing relative to the acceleration of the expansion).

    Light is moving from any light emitting source (at any x,y,z and t coordinate) in every direction (both from the centre and towards it). However the distance light travels in a Light Year is calculated based on vacuum (no force acting upon it). Relativity says that when Light enters a gravitational field it bends. Gravitaional fields cause things to bend (light, space & time – this scraps an earlier statement I made).

    This could mean that Light is not always travelling at maximum speed. Also as time dilation is a factor as well this could all contribute to expansion of the universe occuring at a rate larger than the distance light can traverse from the same starting point, exactly how though I’m not clear on

    8-)

  • Andrew Thurlow

    Agreed,

    but in 13.75 billion years, light can only travel 13.75 Billion Light Years.

    So the age is just confusing the matter. The real question is, how can the universe be 94 Billion Light years in Spherical Diameter, if light can only have travelled 13.75 Billion Light years since the big bang. The question is simply trying to determine how expansion of the Universe can exceed the distance light can travel (within the allotted time), if all started out simultaneously at the same point in space-time, and without violating the speed of light.

    I find myself stuck between different concepts of the following possibilities (of which all could be wrong and could completely expose my own ignorance to those who are well studied in this kind of thing). Some is no doubt caused by not being able to fully grasp relativity, and trying to apply newtonian principles where they don’t apply (even some of those I’m not quite clear on beyond the every day practical understanding).

    1) Particle Physics – If there exists particles with lower mass than a photon. Then starting the journey from the big bang would allow the expansion to get ahead of light, because these particles could exceed the speed of light (and in fact could not go slower than it). This could mean that we could all be drifting faster than the speed of light, and aren’t aware of the fact that we are playing ping pong on “The Train” in the first place. This is a question of relativity!.

    2) Causality – The Bang itself preceeds the light that is emitted. When A lightning strike occurs, the event or Energy being released occurs before we see the light. Due to our proximity being so close, it seems instantaneous compared to the delay in hearing it. But in actual fact the event happens first, and then we see the light. A concept supported by a visible event at the sun being delayed by 8 minutes before we become aware of it. This could mean that the Universe is not expanding faster than light but has a head start. However even hubbles constant would support that due to increasing accelaration, one day it would expand at least as fast as the speed of light.

    3) Inflation – Expansion of the Universe with mass, density and time dilation taken into account (not to mention the visible Light Horizon at which anything beyond it can never be seen due to the expansion). That closer to the centre space-time and reality are more compact, and closer to the edge, space-time and reality are more spreadout, but Light remains constant.

    However I don’t believe in a “constant” The only constant in the universe is that everything is contantly changing. This is a QED statement as constant implies unchanging, however everything is always moving, hence the dificulty with determining when an object is at rest “at rest”. Light travels in waves however, and the wavelengths change the more they become red shifted. This supports that Light can reach the 94 Billion Light Years distance by only actually making 13.75 Billion light years effort. Light has stretched into the Microwave range.

    There is a lot of variables to process. The mathematics is just to complex for the everday perception of the average person like me (not educated in Calculus). Its not uncommon to take small components and understand small parts, the trouble is trying to put all that you know together to form a big picture. In essence a personal attempt by each of us to grasp the big picture of what is currently understood of the attempts to determine a Grand Unified Theory of everything.

    Each time you re-evaluate it, some aspects become clear, others then become confused, and you forget things, or just end up with more questioning. Each time someone posts a new angle, it takes all manner of thinking just to analyse it, and then it spanners everything that you thought you’d got straight, so you have to start again. Eventually it gets tiresome and the brain goes to mush. Its like trying to track the Algrothim of the entire Quake Engine source code in your head when you only have enough RAM to process a few of the subroutines.

    Haha its great fun trying though (if not futile)!!

    My own constant re-evaluation makes me realise just how difficult it is to perceive something so far from our everyday sensory experience. I’ve now started reading “A Briefer History Of Time”, with this question in mind, to better understand it from a “practical” point of view. As you read it the individual concepts make sense, but when you try to apply it on a grand scale it does your head in. So I try to miniaturise it to fit in my head but it just leads me to more questions and it all unravels. Then you have a good sleep and start again!!

    Makes me realise just how Intelligent Einstein and Hawking are. It takes a monumental effort and constant thinking and re-evaluating, to even grasp how they seem to think all the time as “Second Nature”.

    To have such incredible clarity would be sure be nice” But if you ask them a question about it, would it take them a week to get back to you, while they run the math? Or could they answer without batting an eyelid?

    8-)

    Glad there are still a few people reading this thread from time to time. I’ve almost started using it as a personal notepad for recording things that I’m wrestling with to look back on and re-evaulate along with what everybody else has written.

    I seem to be at an impass however, without actually going back to school to fill in the gaps in my understanding. Bioloigy was the only science I was good at. IT has helped my Logical understanding alot, and I always considered my spatial reasoning to be better than average based on all the documentaries I watch. But I just can’t think that vastly for sustained periods of time (long enough to get it)

  • Andrew Thurlow

    The big crunch versus continued expansion (and ultimate dissipation). This is another one of lifes headaches. There are too many unkonwns in my book, I’m still undecided on this. Although I can see arguments for either angle as being just as valid.

    If the universe is expanding, and apparently faster and faster, then its not slowing down (at least not currently). For it to crunch, it would have to decelerate. Maybe once expansion reaches the speed of light, it would only have the option of slowing down (as it can’t go any faster) and then it starts to crunch.

    I wonder if its valid (from a particle physics perception). Could there be a horizon. That which is slower than light (of greater mass) implodes to a crunch, and that which is faster than light (lower mass particles) keeps dispersing.

    Is there a singularity at the source of the bang or is material still spewing forth (is someone still blowing into the balloon and contributing to continued expansion). Maybe our universe inflates in direct corelation to one that deflates (kind of like infalting a balloon, and then breathing it back in again).

    Is the big bang like a Supernova. It implodes to a point where it then explodes. Some material (including light) escapes from the force of teh explosion, but a core is left behind (like a black hole) which starts to pull material in again. Could this be how a big crunch might work?

    Are black holes part of the handbrake that eventually coalesces everything back and then puts it into reverse and pulls everything back towards each other, and then the black holes themselves crunch intp each other, ultimately back to a single point.

    What is at the centre of each Galaxy, must be something of massive gravitational pull? Does a galactic orbit slowly decay. Will we eventually be pulled into teh centre of the Milky way? Or is there harmonious equilibrium caused by the sheer amount of vacuum surrounding the galaxy, that keeps it spiraling indefinately as a perfect counter balance!

    Some of this brainstorm can probably be ruled out, by what is already known mathematically no doubt! I haven’t really paused to think about any of this yet, its all just soming out as I type (more to process and evaluate).

    I really need to focus on what thing at a time I guess. Thuis could be part of my problem. Not tackling it from a structured and logical perspective. Althoughthe bang itself seems like a logocal starting point. But that immediately raisee the question of what caused the bang.

    8-)

  • partha

    I think I understood.

    end of the day, where science ends philisophy begins, where philisophy ends Almighty comes in.

    Having said so, yes, 13.7 b old picture is captured “now” when it has moved 47 b away “now”

    its moving further away, but

    how further? what is the end point?

    What is end to end distance of Universe

    no u did not complicate, you made it simple