URAIN Posted July 29, 2011 Posted July 29, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? If it expanding then how it possible?
pantheory Posted July 30, 2011 Posted July 30, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? If it expanding then how it possible? The standard cosmological model, called the Big Bang Theory, proposes the universe is expanding based upon the observed redshift of galaxies. Most other cosmological models also believe the universe is expanding based upon the same cosmological redshifts we observe. Only those cosmological models/ theories that propose another explanations for these galactic redshifts believe the universe is not expanding. Standard model theorists believe the universe is expanding based upon several possibilities, the original bang, the Inflation hypothesis, the dark energy hypothesis, a cosmological constant of some kind (anti-gravity), and several other ideas related to the expansion of space.
khaled Posted July 30, 2011 Posted July 30, 2011 I'm not good at physics anyway, but, I think that the theories about the universe and its expanding, those kind of theories were not made because we saw the expand, ..etc. Because all of that is impossible for us to notice in the general form .. so instead of going from observations, they went from astrology basics, observations around the earth ...
Dishmaster Posted July 31, 2011 Posted July 31, 2011 I'm not good at physics anyway, but, I think that the theories about the universe and its expanding, those kind of theories were not made because we saw the expand, ..etc. Because all of that is impossible for us to notice in the general form .. so instead of going from observations, they went from astrology basics, observations around the earth ... No, historically, the idea of an expanding universe is based on the interpretation of observations. At the beginning of the 20th century, it was widely accepted that the universe is a static entity. Even Albert Einstein "invented" a term in his field equations to keep the universe static. It was the observations done by Hubble, who discovered that the redshift of galaxies appeared to be correlated with their distance - although the exact numbers were still very preliminary. Redshift is commonly interpreted as the result of motion away from the observer. Since this redshift basically bserved in all direction, one had to abandon the paradigm of a stable universe and accept that it is expanding.
Greg Boyles Posted July 31, 2011 Posted July 31, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? If it expanding then how it possible? The expansion is not like an explosion where the galaxies are flying apart in a pre-existing void. The balloon analogy is a two dimensional analogy where our universe is represented by the surface of the balloon - two dimensional space rather than three dimensional space. We observe the galaxies as 'flying apart' because the volume of space between them and us is itself expanding, carrying all the galxies with it. In much the same way as the area of the balloon surface is expanding as you blow it up causing any marked points on the balloon's surface to move further apart. No matter where you are on the balloon's surface you will observe exactly the same expansion. There are no privaledged reference points as there would be with an exploding bomb where you could be at the centre of the explosion, observing objects flying away from you, or you could be outside the explosion observing objects both flying away from you and towards you.
khaled Posted July 31, 2011 Posted July 31, 2011 I meant that they interpret observations we observed, but did we observe the big bang for example ...
Rolando Posted July 31, 2011 Posted July 31, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? If it expanding then how it possible? We know that light from distant galaxies is redshifted and that this redshift increases approximately linearly with distance. This can be interpreted as due to a Doppler shift or an expansion of space, as in current doctrine – the Big Bang pardigm. Other explanations for the redshift have been proposed, but so far not found acceptance. We also know that within the solar system, within galaxies, within galaxy clusters and superclusters, there is no such expansion. Also on a lager scale, there are no indications of an overall expansion except for the redshift (time dialtion in ligtht). The Big Bang paradigm has to rely on a set of fudge factors such as dark matter, dark energy, size evolution of galaxies etc. in order to be brought into agreement with observations. Links: What is the currently most accepted model for the Universe? http://www.astro.ucla.edu/~wright/cosmology_faq.html#bestfit Angular size test on the expansion of the universe. http://arxiv.org/abs/1002.0525 A way out of the dark age in cosmology http://arxiv.org/abs/1107.2529 Is the Universe really expanding? http://arxiv.org/abs/1107.2485 Quantitative Comparison of Redshift Mechanisms http://www.marmet.org/cosmology/redshift/mechanisms.pdf
Greg Boyles Posted July 31, 2011 Posted July 31, 2011 We know that light from distant galaxies is redshifted and that this redshift increases approximately linearly with distance. This can be interpreted as due to a Doppler shift or an expansion of space, as in current doctrine – the Big Bang pardigm. Other explanations for the redshift have been proposed, but so far not found acceptance. We also know that within the solar system, within galaxies, within galaxy clusters and superclusters, there is no such expansion. Also on a lager scale, there are no indications of an overall expansion except for the redshift (time dialtion in ligtht). The Big Bang paradigm has to rely on a set of fudge factors such as dark matter, dark energy, size evolution of galaxies etc. in order to be brought into agreement with observations. Links: What is the currently most accepted model for the Universe? http://www.astro.ucl...aq.html#bestfit Angular size test on the expansion of the universe. http://arxiv.org/abs/1002.0525 A way out of the dark age in cosmology http://arxiv.org/abs/1107.2529 Is the Universe really expanding? http://arxiv.org/abs/1107.2485 Quantitative Comparison of Redshift Mechanisms http://www.marmet.or.../mechanisms.pdf Can you please explain what you mean by "time dialtion in ligtht". We also know that within the solar system, within galaxies, within galaxy clusters and superclusters, there is no such expansion. Also on a lager scale, there are no indications of an overall expansion except for the redshift (time dialtion in ligtht). The Big Bang paradigm has to rely on a set of fudge factors such as dark matter, dark energy, size evolution of galaxies etc. in order to be brought into agreement with observations. Red shift increases with distance. Could it be that the distance within the solar system, galaxies or galaxy clusters that the distances are to small for there to be a measurabe red shift or are methods of measurement precise enough to be able to detect minute red shifts? Could it have anything to do with the lumpiness of the universe and/or uneveness of expansion?
Rolando Posted July 31, 2011 Posted July 31, 2011 Can you please explain what you mean by "time dialtion in ligtht". In redshifted light, the wavelengths are longer, as if time was passing slower. This is called time dilation, and it has also been observed in the light curves of distant supernovae. Red shift increases with distance. Could it be that the distance within the solar system, galaxies or galaxy clusters that the distances are to small for there to be a measurabe red shift or are methods of measurement precise enough to be able to detect minute red shifts? Within the solar system, the effects are really very small, but in galaxies and galaxy clusters, they would be measurable.
Greg Boyles Posted August 1, 2011 Posted August 1, 2011 Within the solar system, the effects are really very small, but in galaxies and galaxy clusters, they would be measurable. Ahhh, but within galaxies and galaxy clusters presumably gravity has won out locally over expansion. In which case expansion of the universe is indeed uneven due to the presence of large concentrations of matter.
URAIN Posted August 1, 2011 Author Posted August 1, 2011 From redshift we only know distance between galaxies increasing. But we will not know how this universe expanding? which force is making it to expand.
Dishmaster Posted August 1, 2011 Posted August 1, 2011 From redshift we only know distance between galaxies increasing. But we will not know how this universe expanding? which force is making it to expand. Yes, we only know that the universe is expandinfg, but not what is causing it. It is generally referred to as the Dark Energy, but nobody knows what it actually is. 1
Rolando Posted August 1, 2011 Posted August 1, 2011 Yes, we only know that the universe is expandinfg, but not what is causing it. It is generally referred to as the Dark Energy, but nobody knows what it actually is. In the standard cosmology, the expansion is due to a Big Bang that just happened some time ago. "Dark Energy" is invoked in order to account for an apparent acceleration of this expansion. 1
pantheory Posted August 2, 2011 Posted August 2, 2011 (edited) We know that light from distant galaxies is redshifted and that this redshift increases approximately linearly with distance. This can be interpreted as due to a Doppler shift or an expansion of space, as in current doctrine – the Big Bang pardigm. Other explanations for the redshift have been proposed, but so far not found acceptance. (bold added) Good comments Rolando. I believe other conceivable explanations for the observed redshifts are no longer considered at all since they would be inconsistent with the Big Bang model. We also know that within the solar system, within galaxies, within galaxy clusters and superclusters, there is no such expansion. Also on a larger scale, there are no indications of an overall expansion except for the redshift (time dialtion in ligtht). I think this is an observational problem with the BB model. The Big Bang paradigm has to rely on a set of fudge factors such as dark matter, dark energy, size evolution of galaxies etc. in order to be brought into agreement with observations. I agree and consider these fudge factors as being comparable to Ptolemy's epicycles and based upon both wrong underlying assumptions of the model and wrong formulations of the model. What is the currently most accepted model for the Universe? http://www.astro.ucl...aq.html#bestfit Angular size test on the expansion of the universe. http://arxiv.org/abs/1002.0525 A way out of the dark age in cosmology http://arxiv.org/abs/1107.2529 Is the Universe really expanding? http://arxiv.org/abs/1107.2485 Quantitative Comparison of Redshift Mechanisms http://www.marmet.or.../mechanisms.pdf Edited August 2, 2011 by pantheory
Airbrush Posted August 2, 2011 Posted August 2, 2011 (edited) "...Within the solar system, the effects are really very small, but in galaxies and galaxy clusters, they would be measurable." Within the solar system, also within our galaxy, within our local cluster of galaxies, and within our supercluster of galaxy clusters, there is NO expansion. There is not "realy very small" expansion, because gravity wins on small scales. Only superclusters of galaxies are moving apart from other superclusters. There is absolutely NO expansion within a supercluster of galaxies. The expanding motion from the Big Bang and the acceleration from dark energy are overcome by gravity within superclusters. Edited August 2, 2011 by Airbrush
Rolando Posted August 2, 2011 Posted August 2, 2011 Within the solar system, also within our galaxy, within our local cluster of galaxies, and within our supercluster of galaxy clusters, there is NO expansion. There is not "realy very small" expansion, because gravity wins on small scales. Only superclusters of galaxies are moving apart from other superclusters. There is absolutely NO expansion within a supercluster of galaxies. The expanding motion from the Big Bang and the acceleration from dark energy are overcome by gravity within superclusters. This is correct if you adopt the "expanding Universe" view (Doppler shifts). As for the "expanding space" view, there is no consensus on this point. In this alternative, we and our measuring devices must be excepted from the expansion, and it depends on where the limit for this exception is placed.
Airbrush Posted August 2, 2011 Posted August 2, 2011 (edited) ....As for the "expanding space" view, there is no consensus on this point. In this alternative, we and our measuring devices must be excepted from the expansion, and it depends on where the limit for this exception is placed. I don't understand what you mean by "there is no consensus on the expanding space view". Could you please elaborate? It seems obvious that galaxies are not flying apart. They are tightly bound and have been for Billions of years. How could they be expanding? Also, our solar system does not seem to be expanding over Billions of years. Even if there was a tiny expansion, the effects would be noticed over long periods of time. http://en.wikipedia.org/wiki/Metric_expansion_of_space "For much of the universe's history the expansion has been due mainly to inertia. The matter in the very early universe was flying apart for unknown reasons (most likely as a result of cosmic inflation) and has simply continued to do so, though at an ever-decreasing rate due to the attractive effect of gravity. In addition to slowing the overall expansion, gravity causes local clumping of matter into stars and galaxies. These stars and galaxies do not subsequently expand, there being no force compelling them to do so." Edited August 2, 2011 by Airbrush
Rolando Posted August 2, 2011 Posted August 2, 2011 I don't understand what you mean by "there is no consensus on the expanding space view". Could you please elaborate? It seems obvious that galaxies are not flying apart. They are tightly bound and have been for Billions of years. How could they be expanding? Also, our solar system does not seem to be expanding over Billions of years. Even if there was a tiny expansion, the effects would be noticed over long periods of time. Your claim was: There is absolutely NO expansion within a supercluster of galaxies. This can only be a theoretical prediction. No such expansion has been observed. This is true, but it might be due to the smallness of the effects. So, my comment concerned the theoretical predictions. In the perhaps most popular model, it is assumed that the observed redshift in the spectra of distant galaxies are due to an "expansion of space". In this model, at least our instruments of measurement have to be excepted from this expansion. If everything up to superclusters of galaxies is excepted, your assertion is of course correct, but among researchers, there seems to be no consensus on where to draw the boundary.
Airbrush Posted August 2, 2011 Posted August 2, 2011 (edited) This can only be a theoretical prediction. No such expansion has been observed. This is true, but it might be due to the smallness of the effects. So, my comment concerned the theoretical predictions. In the perhaps most popular model, it is assumed that the observed redshift in the spectra of distant galaxies are due to an "expansion of space". In this model, at least our instruments of measurement have to be excepted from this expansion. If everything up to superclusters of galaxies is excepted, your assertion is of course correct, but among researchers, there seems to be no consensus on where to draw the boundary. I appreciate your point of view. How can expansion be "observed"? All they have to work with is red shifts. I'm not sure what you mean by there being no consensus among researchers on where to draw the boundary. I'm thinking the boundary is superclusters of galaxies. Where else can it be? Our instruments of measurement are certainly bound by electromagnetic forces, far stronger than gravity. I just can't understand what your point is, and I would like to, if you would care to expound a little more. What else may cause the red shift? Andromeda is one of the very few galaxies that are blue shifted because it seems to be headed towards us. Edited August 2, 2011 by Airbrush
Greg Boyles Posted August 2, 2011 Posted August 2, 2011 I appreciate your point of view. How can expansion be "observed"? All they have to work with is red shifts. I'm not sure what you mean by there being no consensus among researchers on where to draw the boundary. I'm thinking the boundary is superclusters of galaxies. Where else can it be? Our instruments of measurement are certainly bound by electromagnetic forces, far stronger than gravity. I just can't understand what your point is, and I would like to, if you would care to expound a little more. What else may cause the red shift? Andromeda is one of the very few galaxies that are blue shifted because it seems to be headed towards us. A strong gravitational field causes red shift of any radiation attempting to leave it. A black hole causes so much red shift to the point that the wavelength becomes infinitely long and the photons loose all their energy.
Airbrush Posted August 2, 2011 Posted August 2, 2011 A strong gravitational field causes red shift of any radiation attempting to leave it. A black hole causes so much red shift to the point that the wavelength becomes infinitely long and the photons loose all their energy. Then why are all the red shifts directly proportional to how far away the galaxies are? The distances are estimated based on certain types of supernovas. If strong gravitational fields are causing the red shifts we see, they should be random. Also, the supermassive black holes at the center of galaxies are far too weak to influence the entire galaxy's red shift. What am I missing?
Greg Boyles Posted August 2, 2011 Posted August 2, 2011 Then why are all the red shifts directly proportional to how far away the galaxies are? The distances are estimated based on certain types of supernovas. If strong gravitational fields are causing the red shifts we see, they should be random. Also, the supermassive black holes at the center of galaxies are far too weak to influence the entire galaxy's red shift. What am I missing? Not saying that gravity is specifically the cause of all those red shifts, merely that is another cause of red shift in general.
Aguirre Posted August 3, 2011 Posted August 3, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? It shut be sure that the universe has no skin. Sure is the universe expanding the question is in what kind of structure or non-structure. If it expanding then how it possible? This we will find out. 496=496 In der Ruhe liegt die Kraft Sig
Aguirre Posted August 3, 2011 Posted August 3, 2011 About expanding of universe someone give balloon model. some one says expanding of universe is not correct. Actually what happening? It shut be sure that the universe has no skin. Sure is the universe expanding the question is in what kind of structure or non-structure. If it expanding then how it possible? This we will find out. 496=496 In der Ruhe liegt die Kraft Sig
zapatos Posted August 3, 2011 Posted August 3, 2011 Within the solar system, also within our galaxy, within our local cluster of galaxies, and within our supercluster of galaxy clusters, there is NO expansion. There is not "realy very small" expansion, because gravity wins on small scales. Only superclusters of galaxies are moving apart from other superclusters. There is absolutely NO expansion within a supercluster of galaxies. The expanding motion from the Big Bang and the acceleration from dark energy are overcome by gravity within superclusters. This situation changes somewhat with the introduction of a cosmological constant. A cosmological constant has the effect of a repulsive force between objects which is proportional (not inversely proportional) to distance. Unlike inertia it actively "pulls" on objects which have clumped together under the influence of gravity, and even on individual atoms. However this does not cause the objects to grow steadily or to disintegrate; unless they are very weakly bound, they will simply settle into an equilibrium state which is slightly (undetectably) larger than it would otherwise have been. http://en.wikipedia.org/wiki/Metric_expansion_of_space 1
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