A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Research
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Galaxies without dark matter halos?



 
 
Thread Tools Display Modes
  #91  
Old October 29th 03, 09:56 AM
Phillip Helbig---remove CLOTHES to reply
external usenet poster
 
Posts: n/a
Default Galaxies without dark matter halos?

In article , greywolf42
writes:

The original Hubble constant *is* a doppler shift. That modern
cosmologists have converted this into an expansion parameter
(that works just like a doppler shift, and has the same physics)
is indeed splitting hairs.


The physics of the universe is independent of who on Earth observed
what when.


Yes. What was your point?


That you explain what you mean by "The original Hubble constant *is* a
doppler shift.".
  #92  
Old November 3rd 03, 11:36 AM
Phillip Helbig---remove CLOTHES to reply
external usenet poster
 
Posts: n/a
Default Galaxies without dark matter halos?

In article , greywolf42
writes:

At least the use of the Hubble constant is based on the assumption of known
physics -- the doppler shift.


As I've stated many times in this group, and a few times in this thread,
providing references to referee-journal papers as well as less technical
textbooks, the (bulk of the) redshift of objects at cosmological
distances is not due to the Doppler shift.

At large redshifts, this can get you into trouble. Even if you use the
relativistic Doppler formula, you get the wrong answer. First, it is
not clear WHICH of the many cosmological distances should have its
temporal derivative correspond to the velocity in the formula. Second,
the formula doesn't contain the cosmological parameters. If you believe
the recession velocity at large redshift is given by the Doppler
formula, then you must also believe that this velocity is independent of
the cosmological parameters!
  #93  
Old November 3rd 03, 11:36 AM
Phillip Helbig---remove CLOTHES to reply
external usenet poster
 
Posts: n/a
Default Galaxies without dark matter halos?

In article , greywolf42
writes:

At least the use of the Hubble constant is based on the assumption of known
physics -- the doppler shift.


As I've stated many times in this group, and a few times in this thread,
providing references to referee-journal papers as well as less technical
textbooks, the (bulk of the) redshift of objects at cosmological
distances is not due to the Doppler shift.

At large redshifts, this can get you into trouble. Even if you use the
relativistic Doppler formula, you get the wrong answer. First, it is
not clear WHICH of the many cosmological distances should have its
temporal derivative correspond to the velocity in the formula. Second,
the formula doesn't contain the cosmological parameters. If you believe
the recession velocity at large redshift is given by the Doppler
formula, then you must also believe that this velocity is independent of
the cosmological parameters!
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
"Dark matter" forms dense clumps in ghost universe (Forwarded) Andrew Yee Astronomy Misc 0 November 21st 03 04:41 PM
Galaxies without dark matter halos? greywolf42 Astronomy Misc 34 November 5th 03 12:34 PM
A Detailed Map of Dark Matter in a Galactic Cluster Reveals How Giant Cosmic Structures Formed Ron Baalke Astronomy Misc 3 August 5th 03 02:16 PM
Galaxies without dark matter halos? Ed Keane III Research 4 August 4th 03 12:39 PM
Hubble tracks down a galaxy cluster's dark matter (Forwarded) Andrew Yee Astronomy Misc 0 July 17th 03 01:42 PM


All times are GMT +1. The time now is 07:10 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.