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mysearch
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The question in the title of this thread was triggered after reading a couple of papers that, while accepting the assumption of an expanding universe, seem to question whether space itself actually expands. These papers are:
http://arxiv.org/abs/0707.0380"
Reference: ‘The Expansion of Space and Redshift’ in section 2.6.4
http://arxiv.org/abs/0809.4573"
Reference: ‘The nature of the redshift’ in section 3
While the issue of expanding space has always seem a bit vague to me, mainly because I have never seen a fully rational explanation of the physics that explains how the vacuum of space expands, I have an issue with the premise of these papers based on the current cosmological model, which maybe somebody can help resolve. There are various ‘cosmic calculators’, e.g. Ned Wright, that effectively calculate the expansion of the universe as a function of time via associating redshift [z] to the scale factor [a]. The figures below are taken from the http://www.astro.ucla.edu/~wright/ACC.html" :
As I understand it, a redshift of [z=1089] corresponds to the decoupling of radiation and matter some 0.378 Myrs after the Big Bang. Percentage-wise this is ~0.003% of the current estimated age of the universe. However, the figures of real interest are listed as:
The comoving radial distance: 45.665 Gly.
The angular size distance: 0.041891 Gly.
Again, as I understand it, the 'angular size distance' can be interpreted as the proper distance when the light left the object, while the 'comoving radial distance' in this case approximates to the particle horizon in the current era. On this basis, a redshifted photon arriving on Earth today associated with this event started off some 41 million lightyears in distance, but has been traveling for nearly 13.7 billion years, because the space through which it has been ‘self-propagating’ expanded on route to effectively 13.7 billion light years. The source that generated this photon has now receded to some 45 billion lightyears.
If all this is basically correct and aligns to the accepted model of cosmology, I am not sure how this can be explained other than through the expansion of space. However, I don’t know enough about the practical science of measuring a photon with energy [E=hf] and then associating this to a given redshift on the basis that it was originally sourced in the CMB. However, this might be a question for astro-physics. Anyway, would appreciate any insights. Thanks
http://arxiv.org/abs/0707.0380"
Reference: ‘The Expansion of Space and Redshift’ in section 2.6.4
http://arxiv.org/abs/0809.4573"
Reference: ‘The nature of the redshift’ in section 3
While the issue of expanding space has always seem a bit vague to me, mainly because I have never seen a fully rational explanation of the physics that explains how the vacuum of space expands, I have an issue with the premise of these papers based on the current cosmological model, which maybe somebody can help resolve. There are various ‘cosmic calculators’, e.g. Ned Wright, that effectively calculate the expansion of the universe as a function of time via associating redshift [z] to the scale factor [a]. The figures below are taken from the http://www.astro.ucla.edu/~wright/ACC.html" :
As I understand it, a redshift of [z=1089] corresponds to the decoupling of radiation and matter some 0.378 Myrs after the Big Bang. Percentage-wise this is ~0.003% of the current estimated age of the universe. However, the figures of real interest are listed as:
The comoving radial distance: 45.665 Gly.
The angular size distance: 0.041891 Gly.
Again, as I understand it, the 'angular size distance' can be interpreted as the proper distance when the light left the object, while the 'comoving radial distance' in this case approximates to the particle horizon in the current era. On this basis, a redshifted photon arriving on Earth today associated with this event started off some 41 million lightyears in distance, but has been traveling for nearly 13.7 billion years, because the space through which it has been ‘self-propagating’ expanded on route to effectively 13.7 billion light years. The source that generated this photon has now receded to some 45 billion lightyears.
If all this is basically correct and aligns to the accepted model of cosmology, I am not sure how this can be explained other than through the expansion of space. However, I don’t know enough about the practical science of measuring a photon with energy [E=hf] and then associating this to a given redshift on the basis that it was originally sourced in the CMB. However, this might be a question for astro-physics. Anyway, would appreciate any insights. Thanks
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