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Relativity and Astronomy?
What, if any, special relativity effect evidence themselves in
astronomical data? For instance, according to the HyperPhysics site Super Novae are in theory visible out to 8 billion light years. And according to Hubell's law Super Novae light sources at that distance will have a velocity relative to an earth observer of 0.6c. This corresponds to a relativistic time dilation factor of 1.25, so the tail of super novae luminosity curves should be on average stretched out by 25% for the farthest observable super novae. What kind of data of this type is available? Also, is doppler shifting due to the difference in velocities of approaching and receding arms of galaxies detectable at 8 billion light years and greater? Pat |
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Relativity and Astronomy?
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Relativity and Astronomy?
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Relativity and Astronomy?
Phillip Helbig---remove CLOTHES to reply
wrote: In article , (Pat Dolan) writes: [...] according to Hubell's law Super Novae light sources at that distance will have a velocity relative to an earth observer of 0.6c. This corresponds to a relativistic time dilation factor of 1.25, so the tail of super novae luminosity curves should be on average stretched out by 25% for the farthest observable super novae. What kind of data of this type is available? When distances are this large, forget about using special relativity to do anything related to the "Hubble velocity". One has to use general relativity. The time dilation factor is simply 1+z, where z is the redshift. This is valid in all cosmological models based on GR, even though the actual velocity at that distance (again, both terms have to be defined) can vary depending on the parameters of the model. Let me add that this time dilation of supernova light curves is, in fact, observed: see Goldhaber et al., Astrophys. J. 558 (2001) 359, available on the Web at http://arxiv.org/abs/astro-ph/0104382 . Steve Carlip |
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Relativity and Astronomy?
Phillip Helbig---remove CLOTHES to reply
wrote: In article , (Pat Dolan) writes: [...] according to Hubell's law Super Novae light sources at that distance will have a velocity relative to an earth observer of 0.6c. This corresponds to a relativistic time dilation factor of 1.25, so the tail of super novae luminosity curves should be on average stretched out by 25% for the farthest observable super novae. What kind of data of this type is available? When distances are this large, forget about using special relativity to do anything related to the "Hubble velocity". One has to use general relativity. The time dilation factor is simply 1+z, where z is the redshift. This is valid in all cosmological models based on GR, even though the actual velocity at that distance (again, both terms have to be defined) can vary depending on the parameters of the model. Let me add that this time dilation of supernova light curves is, in fact, observed: see Goldhaber et al., Astrophys. J. 558 (2001) 359, available on the Web at http://arxiv.org/abs/astro-ph/0104382 . Steve Carlip |
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Relativity and Astronomy?
"PD" == Pat Dolan writes:
PD What, if any, special relativity effect evidence themselves in PD astronomical data? For instance, according to the HyperPhysics PD site Super Novae are in theory visible out to 8 billion light PD years. As Philip Herbig and Steve Carlip have pointed out, this is a general relativistic effect. If you are interested in special relativistic effects, my nominations would be synchrotron radiation and superluminal motion. Synchrotron radiation results from relativistic electrons moving in a magnetic field. It is generally accepted to be the emission mechanism for many radio sources. Superluminal motion is effectively an optical illusion resulting from relativistic material traveling toward the observer, e.g., URL:http://www.astr.ua.edu/keel/agn/3c279.html. -- Lt. Lazio, HTML police | e-mail: No means no, stop rape. | http://patriot.net/%7Ejlazio/ sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html |
#7
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Relativity and Astronomy?
"PD" == Pat Dolan writes:
PD What, if any, special relativity effect evidence themselves in PD astronomical data? For instance, according to the HyperPhysics PD site Super Novae are in theory visible out to 8 billion light PD years. As Philip Herbig and Steve Carlip have pointed out, this is a general relativistic effect. If you are interested in special relativistic effects, my nominations would be synchrotron radiation and superluminal motion. Synchrotron radiation results from relativistic electrons moving in a magnetic field. It is generally accepted to be the emission mechanism for many radio sources. Superluminal motion is effectively an optical illusion resulting from relativistic material traveling toward the observer, e.g., URL:http://www.astr.ua.edu/keel/agn/3c279.html. -- Lt. Lazio, HTML police | e-mail: No means no, stop rape. | http://patriot.net/%7Ejlazio/ sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html |
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