Suppose for a minute that there is life at the outer edges of the universe. Since the supposed 'big bang' the outer edges should be slowing down since they have been traveling longer, and anything 'inside' the outer edge would be going faster! Would it not appear to those civilizations on the outer edge, that everything is shifted toward the blue, suggesting a collapsing universe? On the other hand, if the outer edge is moving faster than the 'inside' they must see us moving toward the red also suggesting a collapsing universe because we are closer to the middle. -blueshift
The answer as given by modern cosmology, is "simple". There is no edge to spacetime, and it is expanding uniformly and at the same rate everywhere at once. If you have problems imagining an infinite entity expanding, you can try to imagine that spacetime loops back upon itself, like a sphere with a 3-dimensional surface (a hypothesized alternative to infinitely long dimensions; that is, in the case of the sphere, if you travel long enough in any direction, you will return to your point of origin, unless the sphere expands faster than you can circumscribe it.) Actually, either of these things is pretty damn hard to imagine, so choose whatever works, as there currently is no evidence one way or another (though I believe M-theory, formerly known as string theory, argues for the sphere.) To take a longer-term perspective, it is probable that our entire concept of spacetime is wrong -- similar to how the anscient concept of the firmament of heaven with celestial bodies affixed to moving celestial spheres turned out to be utter nonsense.
Spectral Anaylsis/Expanding Possibly I was not clear. I am not talking about Space, but the bodies (planets, stars, galaxies) in space. If everything is expanding at a uniform rate, how do we get the shift? -blueshift
Unbelievable as it sounds, what I'm going to do is tell you what you really were talking about. Bodies of matter are immune to expansion of space because they are held together by strong quantized forces (electromagnetic, strong and weak nuclear) that are able to counteract the expansion of space. So, space is expanding everywhere, but it's in a way slipping through material objects, unable to pull them apart with it. Objects which are separated, however, in effect get dragged by the expanding space away from each other, as the space between them expands. The expansion is very minute, so we don't notice it. For example, it is dragging the Earth further away from the Sun all the time -- but we do not notice this effect because it is so weak as to be beyond our sensitivity to observe. However, since every unit length of space is expanding by a minute amount, if you take many such lengths of space arranged end to end, their individual expansions add up to a significant total. Thus, the two endpoints of such an enormously long ruler will be moving away from each other with appreciable speed, while any two points on the ruler near each other will be moving away from each other with only an imperceptibly small velocity. So the general rule is, the further away two points are in the expanding space, the faster they are moving away from each other -- even though they are actually standing still with respect to their local space environment; it is the space between the points that is growing. The redshift comes as photons traverse the distance between two such points. A photon is merely a wave-like disturbance in the electromagnetic field. However, the expanding spacetime is the backbone of the field, so as the spacetime expands the field "expands" with it. Thus, traveling waves in the field that were originally very sharp with a short wavelength get stretched out more the longer they travel through their expanding medium. And so, high-frequency light gets shifted to lower and lower frequencies the longer it travels through space. Of course, length of travel for light is just another measure of distance that the light travels. And so it is that the farther an emitter is removed from the observer, the greater will be the redshift in the emitted light by the time it finally arrives. It so happens that the gentle expansion of space becomes noticeable through the redshift in light only over tremendous distances, such as ones that separate one galactic cluster from another. Of course, the ultimate limit of observation is dictated by the age of the universe, which is about 15 billion years give or take a couple billion. Hence, the oldest light emitted by the earliest objects could only travel a maximum distance of 15 billion light years since the universe's birth. Hence, it is physically impossible to observe anything that is farther away from us than 15 billion light years. Within that theoretical limit resides a practical limit supplied by the power of existing telescopes. And within that practical limit, Hubble observed that the further away an object is (and hence the older it is as it's represented by the currently-perceived light), the more red-shifted it looks. And so, the degree of redshift happens to correlate with both distance and age. Anyway, I hope by now you see that you actually were talking about space after all. Please Register or Log in to view the hidden image!
Spectral Analysis/Expanding Boris, Thanks much for taking the time to explain. You get an "A". -blueshift
