Talk:Galaxy/Archive 2

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Archive 1 Archive 2 Archive 3

Etymology

Can someone explain to me what this "Bob" nonsense is. Hera bob her son Zeus bobbed his bob? Huh? Is this for real? —Preceding unsigned comment added by 64.86.141.133 (talk) 11:59, August 30, 2007 (UTC)

It's just silly vandalism. The changes were reverted. — RJH (talk) 15:29, 30 August 2007 (UTC)

Unsourced statement

I removed the following statement from the Etymology section because it has been marked as an unsourced statement since August. It needs a solid reference to be restored on this FA-quality article.

It is thought this myth may have come from earlier Phoenician or even Egyptian myths, where Asherah and Nut (goddess) were portrayed as Goddesses of the Milky Way.

Thanks.—RJH (talk) 20:20, 12 December 2007 (UTC)

New article

Please find a place to include a link to Galaxy color-magnitude diagram. ScienceApologist (talk) 20:20, 18 January 2008 (UTC)

Unless the subject is going to be summarized in the main article I usually insert links to related topics in the "See also" section.—RJH (talk) 20:34, 18 January 2008 (UTC)

"Other nebulae" section

That one I renamed to "Distinction from other nebulae" in order to rectify why the discovery of the Crab Nebula occurs in the middle of that section. The discovery in itself is not important for this article on "galaxy", but it might be a good thing to evolve the picture on how galaxies were increasingly suspected to be foreign milky ways, very far from gaseous clouds while similar but distinct from star clusters. We should also mention that a (naturally) very popular theory during the 19th century and early 20th, that the "spiral nebulae" were new solar systems in the process of formation. Said: Rursus (☻) 09:48, 1 January 2009 (UTC)

Chaucer's byline

Is there a reason Chaucer is listed twice in the byline in the excerpt from The House of Fame? If not, I'm going to remove the second occurrence. —Tonyle (talk • contribs) 08:56, 26 January 2009 (UTC)

Number of known/named galaxies

The article doesn't include an estimate number of galaxies that have been given a name/number. bogdan (talk) 11:01, 24 January 2010 (UTC)

You can probably get a value for a particular catalogue, but finding the total number might be difficult. Then again, STAR Atlas:PRO includes 1,380,500 galaxies and claims to be the most comprehensive such atlas, so perhaps that is the current total.—RJH (talk) 21:28, 25 January 2010 (UTC)

Misuse of sources

Jagged 85 (talk · contribs) is one of the main contributors to Wikipedia (over 67,000 edits; he's ranked 198 in the number of edits), and practically all of his edits have to do with Islamic science, technology and philosophy. This editor has persistently misused sources here over several years. This editor's contributions are always well provided with citations, but examination of these sources often reveals either a blatant misrepresentation of those sources or a selective interpretation, going beyond any reasonable interpretation of the authors' intent. Please see: Wikipedia:Requests for comment/Jagged 85. I searched the page history, and found 13 edits by Jagged 85 in July 2008 and 7 more edits in March 2010. Tobby72 (talk) 10:32, 12 June 2010 (UTC)

Caption Under Galaxy Picture Should Read in 'Light Years', Not 'Parsecs'

Wikipedia articles are supposed to be written for the general public in mind, and no one, outside of astronomy enthusiasts and scientists, knows what a 'parsec' is. Far more people know what a 'light year' is, and so it should instead be used in the caption and the article.

Keep in mind that science writing in Wikipedia is not supposed to be for an exclusive scientific "in-crowd" but instead should be intelligible to the general public-- the "average reader". Scientific terminology may be used, but always in parallel to descriptions that the average person can understand.

98.245.150.162 (talk) 20:24, 20 November 2010 (UTC)

Changed. Materialscientist (talk) 23:45, 20 November 2010 (UTC)

Etymology in article lead

(This is my first time on a talk page, forgive any mistakes)

The name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference to the Milky Way galaxy.

The word ΄γαλαξίας' does not mean milky, it means milky axis (γάλα + άξονας), hence the name Milky Way. The word is not a reference to the Milky Way, the Milky Way is a translation of the greek word. Check the 'Etymology' section in the greek wiki article 79.167.123.182 (talk) 06:04, 24 September 2010 (UTC)

You may be right, but without an authoritative English language citation there's no way for us to be certain. Unfortunately we can't use one wiki article to cite another. Thank you.—RJH (talk) 21:15, 23 September 2010 (UTC)

Well there is no citation for the etymology that is in the article atm. I don't know if this is considered an authoritative citation, but this seems to give a better explanation of the etymology than the lead does. Sorry for making such a fuss, but seriously I read that sentence and lost interest in the article.79.167.123.182 (talk) 06:04, 24 September 2010 (UTC)

Figuring out etymology using a Greek source would be original research. I don't see exactly what the problem is with what is written. Please stick to the facts rather than saying things about yourself like losing interest after reading something you disagree with. No apologies are necessary for pointing out something you think is wrong. Dmcq (talk) 06:41, 24 September 2010 (UTC)
Dmcq, you're being a bit harsh. He provided a good source. As for what's wrong, I should have thought that is obvious (once pointed out!): Galaxy = gala-axis = milky-way, not milky. --Michael C. Price talk 08:37, 24 September 2010 (UTC)
The etymology dictionary is already referenced in the article and it doesn't say it comes from milk and axis because it doesn't come from that. Think of the word galactic which is very close to the Greek genitive case 'of milk'. And there is no etymology section in the Greek article that I can see so I don't know where they got that bit from. There are citations for the etymology in this article and my understanding is they somehow couldn't find them in the article but still came up with one of them to put here. So I would still be interested in what exactly they are talking about as I can't see their point.
As for their feelings they are not relevant to the topic and dragging them in is not constructive. Everyone makes mistakes and they're soonest forgotten if they're quickly corrected and no drama or self worth is invested in the whole business. Dmcq (talk) 13:27, 24 September 2010 (UTC)
So what does ξίας mean in Ancient Greek? --Michael C. Price talk 14:19, 24 September 2010 (UTC)


Well there is no citation for the etymology that is in the article atm. I don't know if this is considered an authoritative citation, but this seems to give a better explanation of the etymology than the lead does. Sorry for making such a fuss, but seriously I read that sentence and lost interest in the article.79.167.123.182 (talk) 06:04, 24 September 2010 (UTC)

Yes well I'm not a big fan of including etymology, but some people seem quite fervent about it. I agree we do need a solid reference. Tough luck about being put off by a single sentence. Life must be easy there. ;-) —RJH (talk) 16:17, 24 September 2010 (UTC)
Citation 14 which the poster referred to and is already in the article is a strong citation and substantiates what's written in the article. The Greek Wikipedia article I think the poster meant was the one for the Milky Way and not Galaxy, they're very similar in Greek. It referred to milk and axis but had no citation and I wouldn't be surprised if someone hadn't just made it up since I can't find any source saying that besides the Greek Wikipedia. Dmcq (talk) 19:09, 24 September 2010 (UTC)

According to:

Skeat, Walter W. (1993). The concise dictionary of English etymology. Wordsworth Editions. p. 168. ISBN 1853263117. Retrieved 2010-09-25.

The original Greek name means stem of milk.—RJH (talk) 21:24, 24 September 2010 (UTC)

I think 'stem' is used there as in the stem of the word means milk. Dmcq (talk) 22:35, 24 September 2010 (UTC)
Okay.—RJH (talk) 18:55, 21 November 2010 (UTC)

I just noticed the 'Etymology' section : The word galaxy derives from the Greek term for our own galaxy, galaxias (γαλαξίας), or kyklos galaktikos, meaning "milky circle" for its appearance in the sky. Wouldn't that be better for the lead?79.167.123.182 (talk) 20:56, 25 September 2010 (UTC)

Cited in scientific literature

Regular contributors to this article might be interested to hear that it has been cited in a paper currently in press with the Publications of the Astronomical Society of Australia. The paper seeks to define the boundary between a small galaxy and a large globular cluster, and refers to the Wikipedia article as one of three common definitions of a galaxy. Modest Genius talk 19:38, 25 January 2011 (UTC)

Interesting read. Maybe we should add something to the effect that galaxies are significantly larger than globular clusters and that mature galaxies have a lifespan longer than the current age of the Universe? Thanks.—RJH (talk) 23:39, 25 January 2011 (UTC)

Redundancy in etymology

Moved etymology text from the first sentence to talk page, as all info appears later in the article (see Etymology). Also was a tad cumbersome (quotes within nested parentheses). [from the Greek root galaxias (γαλαξίας), meaning "milky," a reference to the Milky Way] —Preceding unsigned comment added by 97.97.169.71 (talk • contribs)

The lead is a summary of the article, so some repetition is expected. Having the etymology in the first sentence like that is also (apparently) standard practice here at Wikipedia. I'm not all that happy about that either, but that is supposedly the concensus approach. Sorry. I replaced the brackets with parentheses per the MoS and added the missing closed parenthesis.—RJH (talk) 18:28, 28 January 2008 (UTC)

I'd like to point out that γαλαξίας doesn't just mean "milky", but is a composite word from two roots: "γάλα" (milky) and "άξονας" (axis, direction or way). So, Milky Way, as Voie Lactée in french are exact transliterations of the original greek word. —Preceding unsigned comment added by 129.194.67.230 (talk) 16:34, 16 March 2011 (UTC)

Yes, there is a discuss further below on the topic. Thanks.—RJH (talk) 16:55, 16 March 2011 (UTC)

Black Holes

I may be incorrect but I think that all galaxies revolve around some sort of black hole if this is correct then it should be added to the introduction.The Gaon (talk) 11:08, 7 July 2011 (UTC)

It's mentioned in the fourth paragraph of the lead. There's at least one exception I'm aware of: the Triangulum Galaxy. Regards, RJH (talk) 19:36, 7 July 2011 (UTC)

Another question

The typical diameter of galaxies are now said to be 10000 - 100000 parsecs. Should that be light-years ? —Preceding unsigned comment added by 130.232.94.146 (talk) 08:00, 1 May 2008 (UTC)

No, many galaxies have a much larger diameter than 10,000 light years. Some exceeding 100,000 light years. I suspect if desired the distance could be converted from parsecs to light years, but I don't really see the need for that.--Metalhead94 (talk) 09:31, 18 October 2008 (UTC)
Can we verify the source for this statement? Bibliogrphic link points to article that makes no valid references to this assumption. — Preceding unsigned comment added by 163.192.13.108 (talk) 19:37, 6 October 2011 (UTC)

"tenuous gas" / "gas dust"

"Intergalactic space (the space between galaxies) is filled with a tenuous gas of an average density less than one atom per cubic meter."

I suppose "tenuous gas" is technically true, but I think it gives the wrong impression. Wouldn't it be better to say something like "Intergalactic space is an almost perfect vacuum, containing on average less than one atom per cubic meter."? 86.181.200.83 (talk) 11:51, 28 March 2011 (UTC)

It depends on your perspective, I suppose. One speaks of the interstellar medium of being composed of gas and dust; can't one say the same about the intergalactic medium? It might be more accurate though to say a rarefied plasma. Regards, RJH (talk) 19:48, 6 October 2011 (UTC)

Oh, I just noticed another thing. In the first sentence: "an interstellar medium of gas dust". What is "gas dust"? Should it read "gas and dust"? —Preceding unsigned comment added by 86.181.200.83 (talk) 13:09, 28 March 2011 (UTC)

Yes, another bit of entropy introduced by the internet medium. I've restored the sentence to the correct form. Thanks for the catch. Regards, RJH (talk) 19:43, 6 October 2011 (UTC)

Formation and evolution

The relevant passage in the article says nothing about the role of stars that form in the "star nurseries" or star formation regions (nebulae). could it be the case that stars are being formed there at about the rate they are 'eaten up' by central black holes? and are stars being formed outside of glaxies to then 'fall into them' (pulled by gravitation)? a model that could explain a 'steady state'...? --HilmarHansWerner (talk) 22:34, 26 October 2011 (UTC)

The mass of the Milky Way vastly outweighs the mass of the central black hole. If there was a steady state condition such as you describe, then the core black hole would continue to increase in mass without bounds. In a universe of infinite age with a steady state condition, how would you constrain the mass of the core black hole to its current value?
Note that stars do form in dwarf galaxies, which can then be assimilated into larger galaxies such as the Milky Way. All stars eventually die, so they don't really need to be eaten by the supermassive black hole in order to achieve a type of equilibrium. Regards, RJH (talk) 01:08, 27 October 2011 (UTC)
thanks a lot, RJH, for your answers! "All stars eventually die, so they don't really need to be eaten by the supermassive black hole in order to achieve a type of equilibrium." - point taken. yet a question remains for the more or less intelligently informed layman: why do many galaxies look so damned much like eddies - as do black holes...? (the other galaxies may be less obviously so, but still...) if they were eddies, entertained by the gravitational pull of the center (which may be counteracted somewhat by centrifugal forces), where would the mass, they devour end up then, if we do not presume they grow correspondingly to become ever more massive... could we not assume that matter leaves them in some form of radiation (Einstein's equation...; we would actually nead a term for the common substance of matter and engergy: we might call it "ousía", the most abstract ancient greek term for "what is"...), may be also a kind of radiation not yet seen (or not at all perceivable for us, i.e. our world-state, because not interacting with this part of the world), in order to sort of 'condensate', i.e. 'rematerialize' elsewhere, namely in (intergalactical) star formation regions (first as dark matter?!), where dwarf galaxies would form, out of which larger galaxies then would accumulate... may be my suggestions trigger some stimulating thoughts and answers. I would have to give more explanations of what is behind this thinking. no time for it right now... ;-) --HilmarHansWerner (talk) 00:31, 6 December 2011 (UTC)
Well, a study by Trujillo et al. (2006) showed that the orientations of the galaxies is not random. Presumably the matter that goes to form the spiral galaxies collapses in a manner that provides some net angular momentum to some of the systems along these particular axes of collapse. As for supermassive black holes (SMBH), I think we can assume that they become every more massive. Hawking radiation is fairly negligible for a black hole of that size. However, the jet produced by the SMBH may have the effect of limiting the mass accumulated by the galaxy. Hence the growth is self-limiting. Most of the remaining matter (and probably the dark matter) just ends up in orbit about the galactic center and never comes close enough to the SMBH to become dragged inside. Regards, RJH (talk) 03:20, 6 December 2011 (UTC)

This article is not totally consistent with Wikipedia article on the observable universe

This article states "There are probably more than 170 billion (1.7 × 10^11) galaxies in the observable universe"

The other article states "The observable universe contains about 3 to 100 × 10^22 stars (30 sextillion to a septillion stars),[33][34][35][36] organized in more than 80 billion galaxies" which is a factor of ~20 different. Not I suppose huge in the scale of these figures but enough to be concerning.

It probably all depends on which reference you pick. Currently this article is using Gott et al. (2005). But I suspect there may be a number of estimates depending on who is doing the calculation and with what data.—RJH (talk) 16:07, 27 January 2011 (UTC)

The article now states a number of galaxies in the universe, without using the word 'observable'. Since we have no idea of the size of the universe as a whole, except to say that it is much bigger than the observable part, this now makes no sense at all. — Preceding unsigned comment added by Dickpenn (talk • contribs)

It does in the lead, so what part of the article are you talking about? RJH (talk) 13:55, 6 May 2012 (UTC)

Potentially Misleading

"There are probably more than 170 billion (1.7 × 1011) galaxies in the observable universe,[8][9] and possibly more in a theoretical wider multiverse.[10]" This strikes me as a statement that steps out of the relm of the informative and into that of the speculative in a confusing way. Referencing "multiverse" in an article on something as well established as galaxies could be misleading, and I feel that this sentence would better serve the reader by mentioning that there could be additional (even endless) galaxies that "exist" in the causally disconnected parts of our own universe(whatever it would mean for something to exist in such a manner) than to start talking about the much more general and theoretical concept of the multiverse. — Preceding unsigned comment added by 75.157.19.184 (talk) 06:19, 3 August 2012 (UTC)

Vesto Slipher stuff

In section Distinction from other nebulae it is claimed that Vesto Slipher discovered high redshifts in the brightest spiral nebulae. I found it unlikely that the brightest spiral nebulae should exhibit high redshifts, so I read the source here. He indeed discovered a high radial velocity, a blueshift of 300 km/s. In that source, he did explicitly conclude nothing. The other source was truncated, but this source explain that his real contribution was to assert that the radial velocities of the brightest spiral nebulae was 3 times larger than any other kind of object. And that they rotated. Rursus dixit. (mbork3!) 20:14, 19 August 2012 (UTC)

Right, the text does not say "he concluded that", but rather "indicating that they were moving away at rate higher than...". It was a subsequently inferred conclusion prompted by his results. His discovery was that the spiral nebulae were moving with greater velocity than the stars in the galaxy. Slipher himself didn't come up with the correct interpretation about the expanding universe, perhaps in large part due to experimental error.[1] Regards, RJH (talk) 20:49, 21 August 2012 (UTC)

Star systems vs planetary systems

2nd paragraph: "Galaxies contain varying amounts of star systems, star clusters and types of interstellar clouds. " Shouldn't this be planetary systems? Seems like star systems are much more special cases. Wei wu wei (talk) 22:35, 6 September 2012 (UTC)

Have inserted planets as a separate entry. Planetary numbers would seem to vary with age of the galaxy.John D. Croft (talk) 02:10, 6 November 2013 (UTC)

Number of galaxies

In a number of his videos, Laurence Krauss has stated that the observable universe contains not the 170 billion galaxies claimed in the introduction of this Wikipedia entry, but 400 billion galaxies. Here is one of the videos in which Krauss makes this claim: http://www.youtube.com/watch?v=vwzbU0bGOdc

I'm certainly an expert neither of cosmology nor of editing Wikipedia, so I don't know how such differences of assertion are arbitrated, but given the considerable difference between the two figures I thought that it was worth bringing up. My thanks to anyone who can help arbitrate this.

2602:306:BC58:5910:ADF4:8E86:6FDC:7099 (talk) 13:16, 4 December 2013 (UTC)

Definitely dark matter?

Since dark matter is a 'poorly understood' logical construct built into mathematical models of galaxies, shouldn't there be some sort of qualifier in the opening sentence, rather than saying galaxies are definitely made of the stuff? Probably dark matter, possibly dark matter, could be, maybe, if its ever found to actually exist?Mdw0 (talk) 11:25, 22 December 2013 (UTC)

galaxy is a god particle it's jut near but its so far awy me — Preceding unsigned comment added by 59.180.54.104 (talk) 16:10, 27 December 2013 (UTC)

Semi-protected edit request on 10 September 2014

Hi there I was reading this article and in part of it (under the title of " milky way" I saw a historical mistake.It is about "Al hazen" or "ibn-Haytham" which is called Arabian astronomer. But according to history He is a Persian scientist who born in Basra(Iraq).I request whoever is involved in this article to review non Arabic history documents to see khazeni(Alhazen) is not Arab. thank you Ebrahim50 (talk) 15:01, 10 September 2014 (UTC) Ebrahim50 (talk) 15:01, 10 September 2014 (UTC)

Not done: please provide reliable sources that support the change you want to be made. per cited source on Alhazen:Science, Medicine and Technology, Ahmad Dallal, The Oxford History of Islam, ed. John L. Esposito, (Oxford University Press, 1999), 192;"Ibn al-Haytham (d. 1039), known in the West as Alhazan, was a leading Arab mathematician, astronomer, and physicist. His optical compendium, Kitab al-Manazir, is the greatest medieval work on optics" Cannolis (talk) 04:22, 11 September 2014 (UTC)

Semi-protected edit request on 10 September 2014

I sent an edit request for this article before.But I made a mistake.Actual mistake I was referring to , is about nationality of "Ibn al-Haytham(Alhazen) ".In Galaxy article he is refereed as an Arab astronomer which is wrong.So I want to ask a review about alhazen nationality.According to history(non Arab ones of course) he is a PERSIAN SCIENTIST who born in Basra(Iraq). thank you 174.69.253.20 (talk) 15:10, 10 September 2014 (UTC) 174.69.253.20 (talk) 15:10, 10 September 2014 (UTC)

Could you please supply a source? See WP:VERIFICATION for more information on Wikipedia's requirements. Marteau (talk) 15:27, 10 September 2014 (UTC)
Not done: see above Cannolis (talk) 04:23, 11 September 2014 (UTC)

Ultra Diffuse galaxy

To the authors, Are Ultra Diffuse galaxies covered in this article? Here are 2 links on the subject http://arxiv.org/abs/1410.8141 Cornell University http://www.scientificamerican.com/article/ghostly-galaxies-appear-in-the-coma-cluster Jcardazzi (talk) 12:16, 11 April 2015 (UTC)jcardazzi

Escape velocity of spiral nebulae

Regarding this paragraph:

In 1912, Vesto Slipher made spectrographic studies of the brightest spiral nebulae to determine their composition. Slipher discovered that spiral nebulae have high red shifts, indicating that they are moving away from the Milky Way at a rate exceeding the Milky Way's escape velocity. Thus, they are not gravitationally bound to the Milky Way, and are unlikely to be a part of the galaxy.

I checked Slipher's publications through 1921 and he made no such assertion regarding the escape velocity of the Milky Way, or whether the spiral nebulae were gravitationally bound. All he noted was that the spiral nebulae have higher velocities than those observed for stars, and (by 1921) that the majority were moving away from us. I think the paragraph should be re-written:

In 1912, Vesto Slipher made spectrographic studies of the brightest spiral nebulae to determine their composition. Slipher discovered that spiral nebulae have high doppler shifts, indicating that they are moving at a rate exceeding the relative velocity of stars. He also discovered that the majority are moving away from us.

Praemonitus (talk) 16:56, 17 June 2015 (UTC)

Stars, stellar remnants, interstellar gas and dust, and dark matter.

"dust" seems to be a separate item, so the commas and "and"s look weird.

Should be liek this: stars, stellar remnants, dark matter, and interstellar gas and dust

It looks a liiiiiiiiiiiiiiiiiiiiiitle better

geez guys whats up with yall — Preceding unsigned comment added by 201.54.139.231 (talk) 22:01, 12 March 2015 (UTC)

Even better would be: stars, stellar remnants, dark matter, plus interstellar gas and dust
   ↑ Aabaakawad • (talk) → 18:56, 3 October 2015 (UTC)

Error in Formation subsection.

In the Formation subsection, the sentence "Nearly all the hydrogen was neutral (non-ionized) and readily absorbed light, and no stars had yet formed." is incorrect. In fact, the neutral hydrogen did not readily absorb light. The neutral hydrogen, and all other neutral atoms were profoundly transparent. This transparency prevented heat loss during collapse of gas parcels until molecules were formed (mostly H2 molecules, which are not so transparent). Which is why stars did not form until much later. See Chronology of the Universe ~ Dark Ages and this conversation on Stack Exchange Why did formation of the first stars (population III) not happen earlier?
   ↑ Aabaakawad • (talk) → 19:38, 3 October 2015 (UTC)

What are the other Galaxies really?

Any speculation on the nature or answer asto what the other Galaxies are, must be based on current facts: science, art, physics, observation method, religion, further hypothesies, information technology, meaning.

Science/Physics suggests they ARE other star systems, possibly made of matter and energy and then of the matter of quark content that is currently known. UDSCTB qarks in the nuclear matter. We do not know what the supposed corresponding "electrons, photons, gluons, gravitrons, W,Z mesons" would be. In fact: that these corresponding particles exists in the other Galaxies is a prediction/extrapolation. The shapes is however suggestive that thy do have gravity, since they look like the Milky Way Galaxy.

Art: Observation suggests that these Galaxies contain gas and clumps of matter. The spiral Galaxies look nice, even hospitable, like the Milky Way. Others again looks utterly hostile. We of course would consider the spirals as hospitable, but this does not exclude the possibility that the others are hospitable to other life.

Observation method: these include x-rays, and other frequencies of light. That we see them using light suggests the hypothesis that they are similar in composition to the Milky Way and also that light should be our starting point. Indeed gravitational sensors may or may not be capable of detecting them. They are predicted to sit in space/spacetime.

Religion: the Ancient texts says little about galaxies but do contain records of comets, visiting stars, novas and supernovas. Supernovas were found in other Galaxies. Thus the prediction is that there are similar stuff in other galaxies. Also the Bible says that there exist "heaven" which might refer to stars and other Galaxies. Thus they could be habitat for souls if in fact they are much closer than thought.

Further hypothesies: that the other Galaxies contain matter of quark type UDSCTB and light/radiation. Thet they are far, by their redshift and that they are moving. They suugest we should concentrate on light-technology.

Information technology: we are able to simulate evolution of Galaxies on computers by formulas of cosmology, but they reqiure billions of years of actual time (not computing time). Speculation exists that we and therefore the G--105.225.178.92 (talk) 21:17, 10 June 2016 (UTC)--105.225.178.92 (talk) 21:17, 10 June 2016 (UTC)--105.225.178.92 (talk) 21:17, 10 June 2016 (UTC)alaxies exists on a D-brane: information simulation?

Meaning: that they were created, are special and for our amazement/advancement.

105.225.178.92 (talk) 21:17, 10 June 2016 (UTC)

[1]

References

  1. ^ See current physics textbooks, String theory books, Computational physics, Cosmology, Star Charts, Atlases of Galaxies

Updated information regarding the number of galaxies in the universe

I just added this new information to the Modern research section. I couldn't find the study at the iop.org site, so I used general sources as references. Someone with more access will probably want to both update these references with more scholarly references and better incorporate the new information into both that section and the "Hubble eXtreme Deep Field (XDF)" information window that accompanies this article. grifterlake (talk) 21:24, 13 October 2016 (UTC)

"Approximately 170 billion (1.7 × 1011) to 200 billion (2.0 × 1011),[11] or more recently up to 2 trillion" - Would it be better to just say 170 billion to 2 trillion? — Preceding unsigned comment added by 70.53.221.90 (talk) 01:17, 15 October 2016 (UTC)
That's a pretty vast estimate spread, which is why I added this to the Talk Page after updating the information in the article. A spread of 170 billion to 2 trillion seems very much like a guess. If the recent research is controversial, maybe it should be labeled as such. If the recent research is accepted by the astrophysical community the entire article might need to be updated to reflect the new numbers. Or we can take the easy way our and just say "there be a whole bunch of galaxies out there". ;) grifterlake (talk) 20:15, 15 October 2016 (UTC)

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"Shell galaxies"

There is another theory as to the formation of these. It involves (relatively) sudden and short-lived influxes of matter into galaxies' central black holes, creating "flashes"of light and other energy that travel outwards as spheres, appearing, of course as circles. There are still some issues with this explanation, which is why I've put this comment here, rather than into the body of the article. — Preceding unsigned comment added by 121.218.193.108 (talk) 09:01, 12 July 2017 (UTC)

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External links modified

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upload also: galaxy - A4 dimensions - artist's impression

Andromeda galaxy contrasted and recolored[2] (some few afar stars are montaged) — Preceding unsigned comment added by Arianewiki1 (talk • contribs) 00:12, 13 February 2018 (UTC)

Does galaxy mass follow Zipf's law?

Does galaxy mass follow Zipf's law? If it does then one can easily calculate an upper bound for galaxy mass. Just granpa (talk) 20:57, 23 April 2018 (UTC)

If it does then this suggests that the most massive black hole would be 200 billion solar masses. And of course the most massive Galaxy would be 1,000 times that. Just granpa (talk) 22:29, 23 April 2018 (UTC)

Many galaxies are thought to have supermassive black holes at their active centers

MODERATORS: This article in its introduction states, "Many galaxies are thought to have black holes at their active centers." It would be better described as, Many galaxies are thought to have supermassive black holes at their active centers. - Spacy 73.85.206.197 (talk) 15:52, 24 May 2018 (UTC)

spiral form of galaxies

Why the article do not speak of Cornelis Easton ? see in the swedish wikipedia the article sv.wikipedia.org/wiki/Cornelius_Easton an image of the results of density measures by Easton can be seeen on ipernity.com/doc/r.-platteau/32997173/sizes — Preceding unsigned comment added by 2.5.16.53 (talk) 21:08, 2 September 2018 (UTC)

Galaxy

A grouping of stars, gas, and dust bound together by gravity. Galaxies sometimes have many billions of stars. INTELLIGENT 1234 (talk) 07:08, 11 November 2018 (UTC)

And your point is...? This isn't a forum. The purpose of this page is to discuss improvements to the article. ~Anachronist (talk) 07:34, 11 November 2018 (UTC)

Galaxy databases

I was looking for a current database of galaxies, and found the HyperLEDA site at http://leda.univ-lyon1.fr/. I suggest adding it to the list of databases in the article. — Preceding unsigned comment added by 76.90.72.165 (talk) 22:31, 22 November 2018 (UTC)

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