Talk:Redshift/Archive 9

message: f for frequency was changed in ν. That may be more common in physics books, but f is also in use. IMO, f is much clearer for non-specialists, while ν is easily confused with v for velocity. Harald88 01:16, 5 August 2006 (UTC)
replies: text: Agreed, as long as we mention that f = frequency. --Iantresman 10:03, 6 August 2006 (UTC)
thread_title:  frequency: ''ν'' or ''f'' 

message: I've changed History to a level 1 heading (I think this was left as a level 2 heading from a previous edit) and I've also removed the word redshift from some of the headings where it's obvious that we're talking about redshift (eg. History of redshift -> History). I'm leaving a note here since there is one change I'm not so sure about: Quantifying and interpreting redshift: z -> Quantification and interpretation: z. If I've done wrong, please feel free to revert. Cheers, darkliight[πalk] 14:17, 18 August 2006 (UTC)
thread_title:  Edits to the headings 

message: The cosmological redshift is not a Doppler effect, but is caused by the stretching of space.  It is analagous to the Dopler effect.  The redshift caused by motion through space (eg of stars) is a Doppler effect (not just analogous).  See Gravitation, by Misner, Thorne & Wheeler.
Sorry I am new to this game and forgot to sign the above.  Charlie T, 19 August 06
:This is correct, but that's exactly what the article says at this time. --ScienceApologist 09:11, 19 August 2006 (UTC)
thread_title:  Cosmological redshift 

message: No citations have been provide describing redshift mechanisms as frame transformations; this can be remedied by providing a single attributable quote containing the words "redshift", "mechanism" and "transformation" and any of "Galilean", "Lorentz", or "general relativistic".
I offer the following quotes describing redshift mechanisms, as described in the literature (emphases mine):
*"Modern physics knows two experimentally verified mechanisms which produce redshifts that are independent of wavelength... the Doppler effect ... the Gravitational redshift. Besides these empirical and well understood redshift mechanisms, there is the theoretical phenomenon associated with the expansion of space. [...] Thus three redshift mechanisms act in nature." -- Discovery of Cosmic Fractals] (2002) by Yurij Baryshev, Pekka Teerikorpi
*"For historical reasons, small redshifts are often quoted in velocity units: the radial velocity required to produce the observed shift strictly from the Doppler mechanism due to relative motions." -- "The Road to Galaxy Formation" (2002) by William C Keel
*"Attempts to interpret the red shift by a gravitational mechanism ... efforts have been made to interpret the red shift by a Doppler mechanism", The Red Shift: A Different Mechanism (1972) Urbanovich, S. I.
--Iantresman 16:26, 1 September 2006 (UTC)
thread_title: Verifiable quotes on "redshift mechanisms"

message: About all the fact tags you lefd thruout, don't the links fulfil the need for citations?  Or, why must they be in the same page? -lysdexia 20:54, 23 September 2006 (UTC)
replies: text: No. Otherwise we would not have a referencing system. A person who wants to verify a statement should be directed to either the page of a book or a scientific paper with that conclusion. A link is not sufficient. This may be basic physics knowledge, but most people do not have basic physics knowledge. I'm not sure I understand your second question about the same page. InvictaHOG 21:05, 23 September 2006 (UTC)
thread_title:  note for InvictaHOG 

message: I added a bunch of references. Someone needs to dig up a spectroscopy textbook to reference that section. Other stuff, such as using spectroscopy to study AGN and the rotation of stars, etc... should be easy to find on ADS. I may take a look later if I feel motivated. As for "Effects due to physical optics or radiative transfer", I don't know where to find most of that stuff, but I assume it has been hashed over about a million times on the talkpage, so perhaps it won't be that hard to reference. –Joke 16:12, 6 October 2006 (UTC)
thread_title: Refs

message: Since there are other ways to get frequency shifts in physical optics and radiative transfer, it is inappropriate to unduly weight the Wolf Effect. There is no chance that we will link to every alternative redshift mechanism in this section due to WP:NPOV#Undue weight, so I submit that we remove the reference to this singular effect. --ScienceApologist 13:20, 7 December 2006 (UTC)
thread_title:  Using the Wolf Effect as an example in physical opitcs/radiative transfer 

message: I pretty much understood it - I think. I've actually seen red and green falling stars about 10 ten years ago. Did I get it? I hope so, because it was written in such clear, plain, language. Once again, thanks so much to all who worked on it (The picture is extra-pretty:) )NinaEliza 00:54, 29 December 2006 (UTC)
replies: text: Unfortunately, the color of falling stars is likely due to the chemical composition and temperature of the meteor rather than this effect, but I'm glad you liked the article. --ScienceApologist 02:23, 29 December 2006 (UTC)
thread_title:  Congratulations 

message: I'm mostly out of the wikiproject these days, but I'm a professional astronomer (a postdoc right now), and read through the article pretty carefully. It is very well done, and I doubt that Britannica could cover the subject a fraction as well as it is covered here. Not only are some of the usual fallacies avoided, but some important and clever editorial decisions are made (unifying the discussion under reference frame transformations) that really enlighten the subject. I would be more than happy to recommend this article to a student.
Congratulations to everyone who has worked on this article.
Sdedeo (tips) 03:42, 29 December 2006 (UTC)
thread_title:  Congratulations 

message: I just made a somewhat large edit to the breakdown of linearity in the Hubble Law. The previous version we had was a little unfocused and a bit confusing, and I think what I put in is a better direction to take (i.e., focusing on the breakdown of the Hubble law). But people like dark energy, so like the last version I snuck it in anyway. The material about quantum cosmology is not relevant to the discussion, and I took that out as well. Sdedeo (tips) 18:32, 29 December 2006 (UTC)
thread_title:  majorish edit 

message: If there's a red shift in one direction, does this mean that there will ALWAYS be a blue shift in the opposite direction, and vice versa? JustN5:12 22:13, 23 March 2007 (UTC)
replies: text: Poorly phrased question. If there is a redshift for an object and it is moving 90 degrees to the line of sight, there will also be a redshift for an object if it is moving 270 degrees to the line of sight (opposite direction). If there is a redshift for an object that is moving 0 degrees to the line of sight, there will be a blueshift for an object moving 180 degrees to the line of sight. --ScienceApologist 23:57, 23 March 2007 (UTC)
thread_title:  Red shift in one direction = blue shift in opposite direction and vice versa? 

message: Why doesn't the relativistic doppler effect say that, while we see many galaxies moving at high C-ratio speeds relative to us, we do not know what direction they are moving in? That is, if a galaxy is moving at .7C relative to ours, it will show Lorentz contraction, time dilation, and a redshift no matter what the direction. What convinced us that everything moving fast relative to us is moving away? Thanks.
Bruce Wallman
Brucewallman 18:13, 1 October 2007 (UTC)
replies: text: The Hubble law is works out to very far distances and is not due to the doppler effect, per se. The evidence is tied together with our current understanding of physical cosmology. ScienceApologist 18:30, 2 October 2007 (UTC)
thread_title:  Relative Doppler Effect question 

message: My youth preacher was telling me that this, along with evolution and all the science of origins and what not is junk science. I can go to the evolution page and at least see some mention of this controversy (though it's hardly a fair representation of both sides) but there's not even a mention of the possibility that this isn't true. Why aren't both sides presented?  —Preceding unsigned comment added by 74.227.196.57 (talk) 21:47, 22 October 2007 (UTC)
replies: text: Just calling the consensus view of redshift "junk science" doesn't give me a lot to go on. Did your preacher have any concrete criticisms of the view presented in the article? I think you should keep in mind that this view was developed over decades by hundreds of people devoting their careers to it, and based on a lot of very sophisticated measurements. It is not easy for an outsider to even understand the state of the art, much less debunk it. How many years has your preacher spent studying physics and astronomy? But getting back to the article, even if the view of redshift presented there really is "junk science", we can only put things into the article that are based on reliable sources, and the weight given to any point of view must be in proportion to the prominence of that point of view. Can you give us a source calling the consensus view of redshift "junk science" or challenging it with scientific arguments? Is this source reliable for the information it provides, and does it represent a significant viewpoint within the scientific community or society at large? These are the ground rules we have tried to follow in writing this article. You are welcome to contribute and correct us where we may be wrong, but be aware that you will have to follow the same rules. --Art Carlson 07:53, 23 October 2007 (UTC)
replies: text: Dude quit wasting your time on wikipedia. You can't even tell when people are being facetious anymore.  —Preceding unsigned comment added by 74.227.196.57 (talk) 16:53, 24 October 2007 (UTC)
thread_title:  Junk Science?