The furthest most object yet to be discovered was announced recently. A galaxy 13.2 billion light years away, whose presence was discovered via the process of gravitational lensing.
What I'm having difficulty in coming to terms with however is the following...
If the light that we are now seeing from that galaxy has been traveling to us for 13.2 billion years, and keeping in mind that the universe is ever expanding, where in relation to our milky way galaxy was it 13.2 billion years ago? and where is it in reality now?
I find it quite daunting that everything that we see in the night sky is not actually there but rather we are seeing it as it was when the light actually left the object. Some of them may in fact not even be there anymore at all!
Actually, on the point of the ever expanding universe, does anyone know where the actual point where the big bang originated from is located? At first it would appear that if everything is expanding outward from the point of an initial explosion, objects near us would be traveling away from that point in a similar direction whereas objects on the opposite side of that point would be traveling away from us, but then I read that in actuality everything is moving away from everything else at the same rate (like dots on a deflated balloon which suddenly gets inflated).
I've tried reading Stephen Hawking on the matter but had to admit defeat after he started baffling me with maths. If anyone can enlighten me on any of my ramblings above or point me towards any sites that you've found useful on this subject I'd be grateful.
Well to me it sounds like you've got to grips with it.
I decided a long time ago that Douglas Adam's explination using sponge cake and chemists was the best way to think about the universe.
I'd love to talk about this one down the pub.
Sounds good to me, I always find that I feel more intelligent after a couple of pints.
I think it has something to do with the alcohol killing off the weaker brain cells thus leaving your brain more efficient!
Ah ha, the Darwin theory of brain cell development as used by students. Having never tried alcohol I have no idea what your going on about :wink:
This article seems to describe relevant theory in accessable manner(section II - cake again :smile:)and other stuff!
http://www.ncsu.edu/felder-public/kenny/papers/cosmo.html
Another thing to remember is that when you look at an object, for example the Andromeda Galaxy - what you are looking at is a warped view of the galaxy because, again, the light from the front of the galaxy reaches us before the light at the furthest part of the galaxy. Therefore, even our image of one object in space is totally wrong and what we are looking at is a warped image of something that would not resemble what it really looks like if the speed of light were infinite.
Your analogy of the balloon is a good one. As I understand it the redshift is caused by the fact that space itself is expanding, rather than that the galaxies are moving apart through space with Newtonian motion (although locally galaxies do move with respect to each other). This means that as space expands it changes the frequency of the light already moving through it. Apparently the most distant galaxies we see have had their light stretched by a factor of 6 and appear to be moving away from us at 90% light speed.
Like you I have difficulties coming to grasp with these theories, especially the relationship between the speed of light and time which seems to be at the core of undersanding modern cosmology. I think a couple of pints definately helps understanding!!
A great book to read on this is "The Universe in a Nutshell" by Hawking, and there's loads of others at the library.
There's also a series of talks on cosmology at Greenwich Maritime Museum next saturday if you're interested, entitled "The Big bang: the Beginning and End of our Universe". detauls on http://www.nmm.ac.uk/openmuseum
Some interesting references there, thanks everyone.
As Jim has already said, it is all to do with Space/Time. This is not a concept that can easily be grasped in our very human minds. Virtually everyone, including me, are so fixed with the idea that if we perceive an object at a distance locally, then it possosses not only a "fixed" distance but it also has a "fixed" time. Therefore we can unlock Space/Time, if we only talk about, say, the Earth. A good example of this unlocking of Space/Time is a Ordnance Survey map. It shows various places seemingly on a flat surface and at fixed distances. At no time does it attempt to show the Time relationship. On scales like these Time has such a small input we can "forget" it.
So all understanding of our universe is from a very singular point of view unlocked from the Space/Time concept. Therefore, when we want to try and understanding the much bigger picture where Space/Time cannot be unlocked, we find it impossible. It is as if we have been brainwashed since childhood into thinking Time is not a fundamental part of our universe and that we only need to understand Time in relation to catching a train or boiling an egg.
Sue has mentioned a link. This may help to understand the problem "we" have about distances and their relationship.
To show just how bad the situation is, when I think of the universe it even has an edge!
But is time something that can truly be quantified anyway? Is time real or is it just a concept created by humans to explain what they see around them?
...and what's the chance, given the general curvedness of space and all this other weirdness, of it turning out we're looking at our own galaxy in an earlier life in some of those deep field photos?
That;s an interesting idea. Rather than the universe being infinite, what if when you reached the edge you came back in at the other side, i.e. keep travelling in a perfect straight line and youend up back were you were if you travelled long enough. In which case with a very powerful scope you could indeed be looking at a very early version of our own galaxy.
Hmmmm........
Interesting stuff.
On the point of a finite versus an infinite universe what are your thoughts on Olber's Paradox? i.e. If space is filled with an infinite number of stars in every direction then our night sky should be permanently bright due to the fact that light would be traveling towards us from every part of the sky.
I've heard a number of different theories about this, one of which is that the further away a star is the faster it is receding and therefore the farthest stars are redshifted below the visible region. Personally though I do not believe that the universe is infinite but probably looks more like that diagram on the BBC site about the Hubble ultra deep field that was posted yesterday.
It's all very thought provoking though and I guess at some point we all just have to admit that nobody really knows the answer and until the technology exists we probably never will.
My God I never thought of that! - what a fascinating idea! Time travel springs to mind.