View Full Version : Are there any galaxies which niether red shifted nor blue shifted?
QAZIS
Feb 8, 2011, 02:20 PM
excon
Feb 8, 2011, 02:26 PM
Hello Q:
I don't know, but it's a great question... However, I can't imagine another galaxy moving in tandem with our own.
excon
ebaines
Feb 8, 2011, 03:16 PM
It's safe to say the answer is no, since for a galaxy to not have any red shift or blue shift requires that the galaxy not be moving at all relative to us. This would be highly unlikely - it would be like watching leaves blowing across your back yard and seeing two leaves maintain a constant distance apart from each other. However, galaxies are composed of millions of stars, and the actual red shift or blue shift of the galaxy as a whole can be dwarfed by the red or blue shift caused by the movement of individual stars in the galaxy. So it's possible that we see both red shift and bue shift from the same galaxy, especially in galaxies in our own "local" neighborhood where the effect of cosmic expansion is small.
QAZIS
Mar 14, 2011, 01:41 PM
Thanks ebaines. I was once at a discussion that all the galaxies are moving in circular or elliptical paths around what may be the center of the universe,like electrons to the atoms. If it is the case the galaxies which are at the extreme boundaries or at the fringe of that path will (I) either have no significant red or blue shift or (ii) they will first show up with a red shift then a blue shift or vice versa.
QAZIS
Mar 14, 2011, 01:43 PM
Me too excon :)
ebaines
Mar 14, 2011, 01:53 PM
I was once at a discussion that all the galaxies are moving in circular or elliptical paths around what may be the center of the universe,like electrons to the atoms. if it is the case the galaxies which are at the extreme boundaries or at the fringe of that path will (i) either have no significant red or blue shift or (ii) they will first show up with a red shift then a blue shift or vice versa.
I don't know what discussion this was, but it's not at all in agreement with the generally-accepted idea of an expanding universe. There is no "center" of the universe - or more correctly, all points can be considered to be the "center," as galaxies are receding according to Hubble's Law at a rate that is proportional to their distance from the observer alone and not their direction, and the distribution of galaxies is remarkably uniform in all directions, for all observers. So there is no center that would have all galaxies in some sort of orbit about it.
paraclete
Mar 19, 2011, 03:35 AM
I think it is possible our local cluster falls within your definition although andromedia is said to be moving towards us and would be blue shifted
QAZIS
Apr 10, 2011, 01:04 PM
Is there any room for some new idea or theory? Or is that all?
ebaines
Apr 10, 2011, 03:03 PM
The beautiful thing about science is that there is ALWAYS room for new theories. The only requirement is that the new theory must do a better job of explaining why we see what we see better than the old theory, or else it will not be accepted. In reality what often happens is a new theory comes along that plugs certain "holes" in the old theory but opens up a few more holes, and so then the debate starts as to whether the new theory is in fact better than the old.
QAZIS - the hole I see in your theory is that it doesn't explain why the red shift that we see in galaxies is dependent only on the distance a galaxy is from us, and not on its direction from us. If all galaxies were rotating about some central point then the red shift we observe woud depend on the galaxy's position relative to that central point as well as its distance from us. This is NOT in agreement with observation.
QAZIS
Apr 11, 2011, 02:09 PM
Hmmm, yeah. But what if the path galaxies are revolving around a central point, is not circular ? I mean if it is of some other shape? If then the red shift will also depend upon position?
Or if its circular, and so huge that it will take more to time to be blue shifted?