Talk:Quasar/Archive for 2018

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Recent updates

It's good to see this article getting some attention, as it definitely needs some work. However, a recent update has added a very long section on the "redshift controversy". In my view this section is altogether too long and adds too much detail that is not essential or desirable for a Wikipedia-level description of what a quasar is. There is a false balance problem here: the current text puts far too much emphasis on the idea that there was a general "controversy", when in fact the majority of astronomers accepted the evidence for cosmological redshifts much earlier than is implied by the current wording of the article, and the idea that there was an ongoing controversy gives too much credence to what was basically a fringe viewpoint held by a very tiny minority of astronomers. My suggestion would be to eliminate "redshift controversy" as a subsection of the article, and instead reduce this content to perhaps a few sentences or a paragraph in the historical section focusing on the early uncertainty about the nature of quasars and how astronomers determined that the redshifts were cosmological in origin (rather than focusing on the idea that there was a controversy). It could be explained in at most a sentence or two that by the 1970s the idea of non-cosmological redshifts had become a fringe viewpoint that was rejected by the vast majority of astronomers based on the body of evidence favoring the cosmological redshift interpretation, although a tiny number of astronomers continued to advocate the non-cosmological interpretation into the 1990s and early 2000s. For a description of the early history, this paper is a good reference.

Beyond that: there are various inaccurate statements & minor errors in various sections of the article as it currently stands, and a lot of room for improvement in the references that are given for various facts, and definitely a lot of room to expand the article by adding more content about the physical properties of quasars, quasar surveys and methods for detection of quasars, quasar evolution, etc. So, lots of work to do here. Aldebarium (talk) 00:44, 15 May 2018 (UTC)

I completely agree with you, but hadn't taken the time to say so. A lot of the "new" section about the "redshift controversy" here was moved from Halton_Arp, which is where I think it should have stayed. Pinging User:FT2 who made those edits. - Parejkoj (talk) 16:37, 15 May 2018 (UTC)

As I look over the article more, the history section needs a ground-up rewrite. Text is repeated in various sections, it's excessively verbose, and the timeline is jumbled. Some help reworking it would be appreciated. - Parejkoj (talk) 07:31, 4 June 2018 (UTC)

Agreed, and I'd like to be able to help but probably won't be able to spend much time on this for a while. About the redshift controversy question, my suggestion would be to have a section with a title something like "Development of physical understanding" (after a section describing the initial discovery of quasars and initial redshift measurements) which would address the two related but distinct topics of how astronomers developed the general understanding of (a) the power source and physical properties of the central engine and (b) the cosmological origin of the redshifts. It's true that there was major uncertainty and even controversy about both of these issues in the early years and it would be worthwhile to describe the history briefly, but the idea of noncosmological redshifts was discarded by the majority of astronomers earlier than is implied by the currently written text. I found this paper interesting, it's a good illustration that by the mid-1970s the idea of noncosmological redshifts had really become untenable. Aldebarium (talk) 14:35, 4 June 2018 (UTC)

Sorry, I didn't notice this (or my talk page message) until now.

I moved that text there, because "Redshift controversy" was linked to, and covered in, the Halton Arp biographical article which was clearly inappropriate for an at-length discussion of the cosmological debate itself. I make no claim how significant it was, but it probably should be covered - complete removal would probably be overdoing it.

Looking at the edits since May 2018, the main change seems to be the removal of two paragraphs "In 1967, Arp noted" through to "appeared to support Arp's hypothesis<ref>...</ref>". The first of these paragraphs seems to be recounting part of the background of discovery/understanding, rather than over-emphasizing a fringe view of the time, and the second appears to be a prominent alternative view proponent at a time when those views were not, apparently, fringey (as they were by the 1970s/1980s with new knowledge). I'm not seeing these as false balance since they cover a genuine historical perspective not otherwise mentioned, in a section covering how perspectives and understandings historically evolved, and because their erroneous nature is made very clear.

Can those two paragraphs be looked at again, to check that useful knowledge on the process of understanding in the 1950s/1960s hasn't been removed by mistake, and that we aren't accidentally engaging in recentism of a kind, by viewing legitimately non-fringe views held at the time, in terms of understandings that only became the standard view at a later time? FT2 ^{(Talk | email)} 13:52, 14 June 2018 (UTC)

Look at the original articles from that time: Arp was cited by others, but often just in passing. There really wasn't much of a "controversy" regarding the cosmological origin of the quasar redshift in the literature, and what little there was, was essentially settled by the early 1970s. We should mention Arp, but briefly, and with appropriate WP:WEIGHT. I don't think we should cite his book in this article at all. - Parejkoj (talk) 16:56, 14 June 2018 (UTC)

Thanks, Parejkoj - knowledge what was actually fringe or not, is a bit more specialist knowledge than I have got. I have 2 questions, perhaps you can advise:

1. If one were to briefly and with due weight, sum up alternative views or suggested ideas, during say 1960 - 1975, meaning, those that had significant discussion or were supported by well-known "heavyweight" proponents, rather than "crackpot fringe" stuff, which would be the suggestions/proponents that we should at least mention briefly?
2. It seems that one part of the evidence was the discovery/confirmation of SMBH's at galactic centres. I've found a source in 1987 saying it's considered "known" by then, but can you help backtrack for the period 1970 ~ 1985 when that knowledge became mainstream belief, or key papers? Not least, our articles on the Milky Way and Sag A* itself don't seem to give that info, and papers as late as 2005 still seem to be saying it's "more sure" rather than "it's been known for a long time". That info would be useful in this and other articles if you can find anything.

Thanks for the quick reply FT2 ^{(Talk | email)} 09:05, 15 June 2018 (UTC)

Hi FT2, thanks for your contributions to this discussion. I agree that it's important to be wary of recentism, as you noted, and it's certainly true that one can find papers from the 1970s referring to the "redshift controversy" about quasars, so I don't mean to suggest that this wasn't a thing at all, but my concern is really about how much weight & space is given to this issue in the article. As I suggested earlier, my preference would be to have a briefer discussion of this topic describing the early uncertainty in understanding the power source and distances to quasars, describing some of the arguments raised on either side, and how (and when) the ideas of cosmological redshifts and black hole accretion basically became settled topics. It's also important to not give too much weight to Arp's role in the history of quasars. One can find early papers describing ideas of noncosmological redshifts that didn't mention or cite Arp's work at all, and other notable astronomers who contributed to this topic included Fred Hoyle, Geoffrey Burbidge, and Michael Rowan-Robinson. Focusing too much on Arp is in some ways a form of recentism, because he continued to be the best-known defender of the non-cosmological viewpoint into the 2000s, decades after it became a fringe idea (and even beyond fringe really). He became the best-known astronomer associated with this viewpoint but much of that is due to his persistence in maintaining to promote an incorrect idea long after it was demonstrably wrong. When I have a chance I can try to add some more content about how the black hole paradigm became established, and also a couple of references to early papers on noncosmological redshift ideas written by Burbidge, Hoyle, and Rowan-Robinson, just to give some more background on the character of the debate in the 1960s and early 1970s. Aldebarium (talk) 20:18, 18 June 2018 (UTC)

Citations for some of the info on this page

There seems to be some citations missing. In particular, I can't see any reference for "600 Earths per minute" in the Properties section, or indeed for many of the numbers and statements in that section. Can anyone help out?

Jim421616 (talk) 21:52, 3 July 2018 (UTC)