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Shouldn't the curious case of the NGC 7603 be discussed and incorporated into the article? By the configuration of the system, there is a galaxy, a quasar and two faint objects which share the same space (not backgrounding), and they all have different Redshift momentum, how can this be explained? Eduemoni↑talk↓ 16:08, 9 February 2013 (UTC)
This is not acknowledged by anyone other than Halton Arp to be "not backgrounding". jps (talk) 23:24, 30 November 2013 (UTC)
This article claims that Redshift is used in Police Radar Guns. However, these devices are not "spectroscopes" and do not measure redshift. This effect should be properly attributed to Pulse ReflectionOrrerysky (talk) 20:08, 30 November 2013 (UTC)
radar gun does not appear to be a spectroscope capable of analyzing absorption lines. Unrelated topic. Orrerysky (talk) 20:34, 30 November 2013 (UTC)
Please read it again: it does not say spectroscopes are used in radar guns.--JohnBlackburnewordsdeeds 20:50, 30 November 2013 (UTC)
The Redshift Effect is very specifically in regards to the measure of absorption lines & emission lines in a spectrograph. Given that radar gun is not measuring a displacement in absorption or emission lines, I fail to see how it relates to the topic. I propose this section be removed and added to Pulse ReflectionOrrerysky (talk) 20:54, 30 November 2013 (UTC)
"Redshift" refers to the shifting of the spectrum of an object toward longer wavelengths. It does not refer to simply measuring absorption and emissions lines in a spectrograph otherwise there would be no such thing as photometric redshift, for example. jps (talk) 23:20, 30 November 2013 (UTC)
That's great, perhaps you can explain to me how a radar gun works to measure redshift when its specifically calibrated for Pulse_(physics)#Pulse_Reflection of a signal with the same frequency and wavelength as what was emitted. This is bad science and misrepresents both redshift, pulse reflection, and radar guns. Orrerysky (talk) 16:19, 1 December 2013 (UTC)
It should be noted in the section on the expansion of space that Hubble later questioned the validity of this theory. On the Problem of the Expanding Universe, Edwin Hubble, American Scientist 1942
If, then, we analyze our data, if we map the observable region, using first one scale and then the other, we may find that the wrong scale leads to contradictions or at least to grave difficulties. Such attempts have been made and one scale does lead to trouble. It is the scale which includes the dimming factors of recession, which assumes that the universe is expanding.
Hubble provides a grave review for expansion interpretation. He also stated that
It merely removes the theory from immediate contact with observations.
Given this factual information, this article should make note of Hubble's positive and negative remarks in order to keep it neutral to Hubble's position. Orrerysky (talk) 20:34, 30 November 2013 (UTC)
The authoritative source on this subject in Cosmology and Controversy by Kragh. In that work, it is clear that the context of Hubble's questioning was one based on his failure to measure the distances to the spiral nebulae properly. His remarks were that either his measurements were wrong or that the expanding universe was wrong. It turned out that his measurements were wrong (he was not looking at Cepheids and instead was looking at H II regions and so he thought the galaxies were much closer and thus the Hubble Constant was much larger). jps (talk) 23:23, 30 November 2013 (UTC)