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11-18-2002, 05:44 PM | #21 |
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Problems with that scheme.
How would matter shrink? I juat don't see any conceivable ways matter can shrink. Everything making up matter, from atoms all the way to the smallest parts would have to be shrinking and how would that be possible? Also, won't as matter shrink, the density will increase until it turns into a blackhole. Lastly, if matter was to shrink, then the perceived distances between the planets and the sun would be increasing. Think of this way, if the earth and the sun were shrinking, then the distance between the two globes would be increasing as the surface areas of the two bodies are compactified. [ November 18, 2002: Message edited by: Demosthenes ]</p> |
11-18-2002, 06:59 PM | #22 | |
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Also, this could not explain observations. For example, it cannot account for the cosmic microwave background radiation. It might be possible to metaphysically claim that everything is shrinking and the physical constants change to perfectly hide that, but it would still require an expansion. More importantly, that hypothesis is unfalsifiable, mostly because it is meaningless. The only measurements that are possible (indeed, that have meaning) are dimensionless ratios (pure numbers - without units). Whe you say that a building is 20 meters high, you are saying that the ratio of the height of the building to the length of a meter is 20. Since these dimensionless ratios would not change in such a scenario, it is meaningless to say that anything is changing. |
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11-18-2002, 07:10 PM | #23 | ||
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If the wavelength of light emitted was larger in the past, and the size of matter is smaller in the present, you have a double whammy on the apparent red shift of light from remote sources. |
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11-18-2002, 09:14 PM | #24 | |
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11-18-2002, 09:59 PM | #25 | ||
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As for what could cause the universe to expand... this is fairly well understood. General Relativity requires that space is dynamic; that is, it may expand or collapse, but will not remain static. The cause of cosmological acceleration is not yet understood, but its existence seems inconsistent with your hypothesis. Oh, another problem. Since you require the speed of light to remain (at least comparitively) constant, our visual horizon would expand faster than light. That is, if we can see 14 billion light years away now, we will be able to see more than 15 billion light years away in 1 billion years. This would also cause the Hubble flow to be a non-linear relation. It is, however, perfectly linear (within experimental error). |
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11-18-2002, 10:24 PM | #26 | |
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I recommend that you read a very good, easy-to-understand paper on <a href="http://www.arxiv.org/abs/astro-ph/9904049" target="_blank">Why Cosmologists Believe the Universe is Accelerating</a> by physicist Michael S. Turner of University of Chicago / Fermilab Astrophysics Center.
Here is an article that offers an alternative to quintessence: <a href="http://www.arxiv.org/abs/astro-ph/0211097" target="_blank">Missing Mass and the Acceleration of the Universe. Is Quintessence the Only Explanation?</a>. It is worth noting, however, that this theory predicts cosmological acceleration for z<1 and cosmological deceleration for z>1 (roughly) and a corresponding discontinuity in the Hubble relation. The only discontinuity that has been found, however, is at about z=6. This is not due to a change in acceleration, however, but rather is an artifact of galactic development. Also, the details of this theory have not been worked out, so it is not known how well it fits all of the data. xCDM (cold dark matter with dark energy cosmology), however, fits the current data perfectly, within current margins of error. Time will tell. [ November 19, 2002: Message edited by: Gauge Boson ]</p> |
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11-19-2002, 04:50 AM | #27 | ||||
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I am not sure that this is an actual problem if you consider the very slow rate of shrinkage that we are talking about. The gravitational attraction between objects can make up for the shrinking (collapse) of matter. Quote:
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Thanks for your critiques |
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11-20-2002, 02:30 AM | #28 | ||||||
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11-20-2002, 09:59 AM | #29 | ||
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A) Billions of years ago ALL matter would have been slightly larger than it is now, thus all light emitted would be of a slightly larger wavelength compared to radiation emitted now B) light emitted from the sun 4.5 billion years ago would not have been in the upper UV strain of light, it would only have red shifted by a 233 nanometers in spectrum (or a 38% difference in wavelength, which translates to a 19% difference in actual size of matter), however, this light interacted with the earth billions of years ago, at a time when the matter of the earth was approximately the same size as the matter of the sun (9 minutes difference in matter size) I've got to go now, but will finish this later. I just had a new idea to chew on while I do my errands. |
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11-20-2002, 11:48 AM | #30 | |
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As for your example, reverse the effect a show your calculations; then you'll have it right. The sun currently emits at a peak wavelength of roughly lambda=500_nm, per Wein's law, in the yellow-green part of the visible spectrum. Because the meter (if defined in terms of a standard object) was longer in the past (here we are getting on a slippery slope because of the problems with changing dimensional constants that I mentioned before), but the wavelength of light was not, the relative wavelength (the only one that matters) was shorter. This can be thought of as follows: the meter was longer, hence the nanometer was longer. Because the wavelength of light was not longer, fewer nanometers would 'fit' across a wavelength of the light. Thus, the relative wavelength was shorter. So the wavelength of light emitted by the sun, if your figures hold, would have been about lambda=400_nm, on the border of visible and UV wavelengths. However, the realtive diameter of the universe was about 2/3 what it is now in the past. Thus, the wavelength of light would have been about 2/3 as great (actually a little more; the observed realtionship is different for redshifts because it is relative velocity that matters, not density), so it would have been roughly lambda=350_nm. That would have been in the UV range (now that I do the calculations, it would have been near-UV). Of course, this is assuming no change in Wein's law, though the curve would be blueshifted in the past, resulting in a higher relative concentration of high-energy photons than now. What you still seem to be missing is that this effect (The shrinkage of matter) would cause the light the sun emits (not only the light that has already been emitted) to increase in relative wavelength with time. The light that was emitted billions of years ago, when it was emitted and relative to Earth then, had a shorter wavelength. Relative to today, the wavelength is the same, but at the time, the energy of the light would have been higher. I must add a clarification to one of my prior comments. I remarked that the cosmic particle horizon would appear to receed superluminally. This is true, but I picked bad units as an example. Measuring in light-years, actually being related to the speed of light rather than the size of anything, would result in the appearance of a normally expanding cosmic particle horizon. Here's why: the cosmic particle horizon receeds at the speed of light. The apparent speed of light, however, is increasing with time in this model. So the light-year increases in length at the same rate that the cosmic particle horizon would appear to exceed the speed of light. This perfectly compensates. But if you use units of length based on the size of a standard, the cosmic particle horizon appears to receed faster than light because more units cover the same proper length with time. Of course, our standard unit of length, the meter, is defined in terms of the speed of light. But we would not have done this in the situation you are proposing because it would result in an ever-increasing relative meter size. It would not be enough to notice typically, but it would definitely have effects on atomic clocks. A strict constraint can be placed on the possibility of this hypothesis. Recently, it has been observed that the fine structure constant was slightly (1 part in 100,000 over 1 billion years) lower in the past (1, 2). The fine structure constant is closely related to the speed of light and this can correspond to a slightly higher speed in the past (3, 4) (we have the same problems with dimensional units (3), but this problem is covered in (4) ). This is opposite what would be expected in your model. So these observations preclude such a model from being an accurate description of the universe. (1) "Further Evidence for Cosmological Evolution of the Fine Structure Constant". Webb, John K.; Murphy, Michael T.; Flambaum, Victor V.; Dzuba, V.A.; Barrow, J.D.; Churchill, C.W.; Prochaska, J.X.; and Wolfe, A.M. <a href="http://www.arxiv.org/abs/astro-ph/0012539" target="_blank">Available on the arXiv e-print archive</a>. (2) "Does the Fine Structure Constant Vary? A Third Quasar Absorption Sample Consistent with Varying alpha." Webb, John K.; Murphy, Michael T.; Flambaum, Victor V.; Curran, Stephen J. <a href="http://www.arxiv.org/abs/astro-ph/0210531" target="_blank">Available on the arXiv e-print archive</a>. (3) "Comment on Time-Variation of Fundamental Constants". Duff, M.J. <a href="http://www.arxiv.org/abs/hep-th/0208093" target="_blank">Available on the arXiv e-print archive</a>. (4) "A time varying speed of light as a solution to cosmological puzzles". Albrecht, Andreas and Magueijo, Joao. <a href="http://www.arxiv.org/abs/astro-ph/9811018" target="_blank">Available on the arXiv e-print archive</a>. Here is a paper which attempts to refute (3). I provide it so that you can try to make up your own mind on this. "Comment on the Variation of Fundamental Constants". Moffat, J.W. <a href="http://www.arxiv.org/abs/hep-th/0208109" target="_blank">Available on the arXiv e-print archive</a>. |
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