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f7u2p
Posted:
Thu Mar 24, 2005 1:26 pm
Joined: 24 Mar 2005
Posts: 6
Location: California
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How is the mass of a galaxy determined?
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Marc
Site Admin
Posted:
Thu Mar 24, 2005 9:20 pm
Joined: 24 Oct 2003
Posts: 115
Location: Ireland
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I think it's generally determined by observing how much radiation (light) is emitted by the galaxy and then observing its rate of rotation, which depends on the galaxy's mass.
Hope this helps,
Marc
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f7u2p
Posted:
Fri Mar 25, 2005 2:14 am
Joined: 24 Mar 2005
Posts: 6
Location: California
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That's as I suspected (that a galaxy's mass is a function of the light it emits). My intrest was triggered by the following remark in the Mar 19-25 New Scientist: "Maybe we can't work out what dark matter is because it doesn't actually exist."
That dovetails with my skepticism about interpreting the red shift of distant objects as a doppler shift. If this red shift is instead interpreted as a degredation or loss of energy by light then the mass calculation of galaxies may be off and we don't need to posit dark matter.
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f7u2p
Posted:
Sat Apr 09, 2005 12:10 pm
Joined: 24 Mar 2005
Posts: 6
Location: California
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If the red shift is not interpreted as a doppler shift, but instead as light loosing energy over intergalactic distances (time), then how would such a conjecture impact relativity theory? I suppose the speed of light would still be an absolute constant, but there would be more to the story. The affect would not just be on cosmology, but on our basic understanding of nature since photons have a role in all material interactions.
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ma1999
Posted:
Thu Apr 14, 2005 3:43 pm
Joined: 14 Apr 2005
Posts: 6
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I have yet to see a proof that Redshift is NOT "light aging" but as a theory associated with expanding universe its not that bad.
If we think that the universe is expanding the redshift fits up. Nothing in an expanding universe theory requires a big bang tough. There is nothing in a expanding universe that requires it to be "zerosize" when it started expanding.
| f7u2p wrote: | | If the red shift is not interpreted as a doppler shift, but instead as light loosing energy over intergalactic distances (time), then how would such a conjecture impact relativity theory? I suppose the speed of light would still be an absolute constant, but there would be more to the story. The affect would not just be on cosmology, but on our basic understanding of nature since photons have a role in all material interactions. |
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f7u2p
Posted:
Thu Apr 14, 2005 11:03 pm
Joined: 24 Mar 2005
Posts: 6
Location: California
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Continuing my conjectures... Assume that the red shift indicates a loss of energy by photons traveling intergalactic times and distances. Assume further that the loss of energy is not due to interaction with matter. Then the loss of energy would be sponaneous as if photons had a half life. This is consistant with a view that nothing lasts forever.
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