Talk:Galaxy

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Stars, stellar remnants, interstellar gas and dust, and dark matter.[edit]

"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)

Escape velocity of spiral nebulae[edit]

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)

Error in Formation subsection.[edit]

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?[edit]

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]

Updated information regarding the number of galaxies in the universe[edit]

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