- #1
turbo
Gold Member
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Hubble's UDF image is visually stunning. It also raises questions for me that I hope can be answered here in terms that I can grasp. I am an amateur astronomer (dabbling in astrophotography) with limited math skills. I marvel at the enormity of our universe every time I step out under dark skies, but the UDF has taken that awe to a whole new level, because it brings up some incongruities (to me anyway) that are impossible for me to resolve without some help.
Official descriptions of the image state that it contains galaxies at z=6 and perhaps even to z=12, which if true means that Hubble has directly observed galaxies that formed only a couple of hundred million years after the Big Bang. There is also the implication that with sufficient telescope time (millions of years!) Hubble could demonstrate to us that the universe is remarkably homogeneous in all directions. In other words, no matter which direction we look, we would see multitudes of galaxies, including highly redshifted faint ones that by inference are very old (a few hundred million years after the Big Bang).
Question 1 - If the above is true, how did the irregularities arise that precipitated the formation of all these galaxies, and why is the distribution (in every direction) so uniform? It seems like a couple of hundred million years is a very brief time for so much galactic structure to develop. Also, I'm guessing that the irregularities must have arisen when the universe was VERY young and compact, or the results would not be so uniform in every direction.
Question 2 - As we survey space with our telescopes, we get the illusion that as we increase the sensitivity of our 'scopes, we are looking farther outward. It appears as if we are at the center of a huge sphere (the observable universe) that appears to grow in volume as our telescopes and sensors improve. This impression is hard to shake, but it must be fundamentally wrong, since if the universe is expanding, the light we see from the faintest, oldest galaxies must have been emitted when the universe was much smaller and more compact. Does anybody have a topological model that can reconcile this problem to a person with limited math skills? Philosophically, I can tell myself that as we look outward far enough in any direction, we are essentially looking back toward a singularity which is the beginning of the universe, but I have trouble visualizing the convergence necessary to work back toward that much younger universe.
Thanks to anybody who can help, or point me to some good resources.
Official descriptions of the image state that it contains galaxies at z=6 and perhaps even to z=12, which if true means that Hubble has directly observed galaxies that formed only a couple of hundred million years after the Big Bang. There is also the implication that with sufficient telescope time (millions of years!) Hubble could demonstrate to us that the universe is remarkably homogeneous in all directions. In other words, no matter which direction we look, we would see multitudes of galaxies, including highly redshifted faint ones that by inference are very old (a few hundred million years after the Big Bang).
Question 1 - If the above is true, how did the irregularities arise that precipitated the formation of all these galaxies, and why is the distribution (in every direction) so uniform? It seems like a couple of hundred million years is a very brief time for so much galactic structure to develop. Also, I'm guessing that the irregularities must have arisen when the universe was VERY young and compact, or the results would not be so uniform in every direction.
Question 2 - As we survey space with our telescopes, we get the illusion that as we increase the sensitivity of our 'scopes, we are looking farther outward. It appears as if we are at the center of a huge sphere (the observable universe) that appears to grow in volume as our telescopes and sensors improve. This impression is hard to shake, but it must be fundamentally wrong, since if the universe is expanding, the light we see from the faintest, oldest galaxies must have been emitted when the universe was much smaller and more compact. Does anybody have a topological model that can reconcile this problem to a person with limited math skills? Philosophically, I can tell myself that as we look outward far enough in any direction, we are essentially looking back toward a singularity which is the beginning of the universe, but I have trouble visualizing the convergence necessary to work back toward that much younger universe.
Thanks to anybody who can help, or point me to some good resources.