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redshift is representative of a change in the geometry of the space in which the galaxies are sitting.
Redshift measures the rate of expansion of the universe. There is nothing pushing on galaxies, redshift is representative of a change in the geometry of the space in which the galaxies are sitting. Looking at the redshifts of galaxies over a range of distances gives us a measurement of the change in the rate of expansion. This provides a measurement of the cosmological constant.
Space-time is being stretched, according to current thinking, and I guess this will stretch locally too. I would be interested in reference to any papers on the potential effects of this on the atomic scale (it must be very tiny).
I have a specific reason for asking this question. Either one believes in expansion of the fabric or they don't. No two ways about it. And if one believes in an expansion of the fabric, they should also support the expansion model of matter. You can't have one without the other. Being a nonsupporter of the expansion theory of matter, I must also reject the fabric expansion model.
Yor-on, I think you nailed it.If indeed "space" is expanding, we would not observe any redshift. That, to me anyway, makes no sense. Redshift can only be associated with an actual change in distance. If space expands, there is no change in distance. (We cannot have it both ways.)Therefore, the observed redshift cannot be associated with an expansion of space.
Quote from: Geezer on 03/01/2010 04:46:03Yor-on, I think you nailed it.If indeed "space" is expanding, we would not observe any redshift. That, to me anyway, makes no sense. Redshift can only be associated with an actual change in distance. If space expands, there is no change in distance. (We cannot have it both ways.)Therefore, the observed redshift cannot be associated with an expansion of space.The expansion of space that causes redshift is an expansion of inter-galactic space relative to the space within galaxies.
Redshift will certainly occur if the distance between our galaxy and a distant galaxy increases. But if the intervening space expands, then it does not seem (to me anyway) that we would observe redshift associated only with the expansion of space. If space itself expands, then distance does not increase with the expansion. The distance is still the same.
As Graham points out, this may just be a vocabulary issue. Would it make more sense to avoid the use of the term "expansion of space"?
Ah! I think I'm beginning to get it. I'm taking "space expands" to literally mean that the fabric of space-time actually stretches. It sounds as if there is actually an increase in the amount of space between galaxies even though those galaxies have not necessarily travelled through space relative to each other. Could this be described as "spatial growth" instead, or would that be even more confusing?
I don't understand what you mean, Joe. What angles are you measuring?Geezer, I think the evidence suggests that the space between galaxies is increasing: other galaxies are moving away from our galaxy (on average) and the further away they are the faster they are receding. I got the impression that it was suggested that this motion was because space was being "stretched" and that this would mean some change in the spacial distances that are measured, even down to atomic and sub-atomic levels. I don't understand this idea (hence asking for a reference). I think someone mentioned that our "rulers" would be stretched too so how would we know. I don't think this is a necessary conclusion that results from accepting that space-time was created in a big-bang. If this concept genuinely has some predictive qualities then it would be worth pursuing, but it seems a bit vague. I would like to know more about it though.