Talk:Astrophysics

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Astrophysics was the collaboration of the week for the week starting on June 4, 2004.

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[edit] Overlap ?

There seems to be a lot of overlap in this field: there's Astronomy, History of astronomy, Observational astronomy (which has almost nothing in it), and Theoretical astrophysics.

In my head, astronomy is the generic word for any study of the heavens: historical, amateur or professional; while astrophysics is the scientific field of study. The OED calls astrophysics "That branch of astronomy which treats of the physical or chemical properties of the celestial bodies." So perhaps this page should primarily deal with the scientific discoveries and theories of the cosmos, and link to the astronomy and history of astronomy pages? --Screetchy cello 00:58, 6 Jun 2004 (UTC)

I agree, there is too much overlap. Astronomy is the scientific study of objects in space, astrophysics is the study of the physical science of objects in space. Unless life is discovered in space, or the definition of science is expanded, all astronomical science is physical science, and so astronomy and astrophysics are the same thing. Indeed the terms are used interchangeably. I think the two entries should be merged. Also I wonder whether history, observational and theoretical really need to be separate entries.

(There is vague notion that astrophysics is more rigorous or quantitative than astronomy; all this means in practice is if you're an astronomer and you're out to impress you call yourself an astrophysicist, whereas if you want to avoid freaking out people out you say you're an astronomer.) --Rkundalini 10:29, 8 Jun 2004 (UTC)

I think the Astronomy wiki has it quite right: Observations are understood as the main work of 'Astronomers,' and the explanation of astronomical objects through theoretical work is what an 'Astrophysicist' does. So, let's concentrate on the physical concepts of Astronomy, here. Awolf002 23:37, 9 Jun 2004 (UTC)

I think Obervational Astronomy is a bit redundant; that's what astronomy is, the observation of the universe. And shouldn't Einstein's contibutions (i.e. Relativity) be included in the history?Trevor macinnis 23:04, 10 Jun 2004 (UTC)

Astronomy literally means the laws of celestial objects, not just the observation of them. But ok I will buy the assertion that in common usage it has come to be associated with observational astronomy, while theoretical astronomy tends to be called astrophysics. Is this a big enough difference to justify two different pages, instead of sections within a single page? I would opt for the latter. Certainly the entries for individual objects should cover both observational and theoretical aspects (imagine having a page on say, star (observational) saying a star is a bright dot on the sky with such and such a spectral energy distribution, and another entry star (theoretical) saying a star is a self-gravitating object undergoing nuclear fusion or so... would be strange!). So it seems weird to divide the field at the top level and not at the bottom level. But ok if people do want separate astronomy and astrophysics pages, can we at least do away with the observational section of the astrophysics entry? And if we do have separate entries, how do we better organise linking structure from each of these entries to objects on specific celestial phenomena/objects? Rkundalini 13:13, 11 Jun 2004 (UTC)

-- Astrophysics isn't just the theoretical side. Astrophysics is the scientific study of the cosmos, both theoretical and observational. Astronomy is more general; you could say, for example, the people who built Stonehenge did astronomy. So I think it's reasonable to have a distinction between astronomy, which is a word for *any* observation or study of the heavens, and astrophysics, which is science.

I envision this page as talking about current scientific theories in astrophysics (the theoretical side), and how scientists observe the cosmos (the observational side).

Some ideas for this page:

  • Big Bang, obviously (this could discuss the cosmic microwave background and red shifting as evidence for why scientists believe this took place.)
  • Stellar formation
  • Large-scale structure - galaxies, etc
  • Tools of the trade - visible observing, but also radio and infrared, and space-based telescopes. Spectroscopy.

Crikey, just in writing this, I'm realizing my astrophysics history is ruuuusty. I need to do some research. Screetchy cello 18:12, Jun 13, 2004 (UTC)

That sounds like a pretty good solution to me. Rkundalini 07:47, 14 Jun 2004 (UTC)

When I created the page like three years ago I called it "Astronomy and astrophysics" for close to the reasons the Rkindalini cites: most of the work done in astronomy is astrophysics, with celestial mechanics essentially complete and astrometry still done, but not by so many people as once was done. Astrophysics is a 20th century creation, but has taken over most of astronomy. The name of the departments in universities in many places has to do more with history than with what they do, so the old departments are called "astronomy department", while the newer ones "astronomy and astrophysics", or some just "astrophysics". But, someone disagreed with me not so long ago and decided to rename the page to "astronomy", what made necessary to create this one. I didn't try to fight back, as most of the links one makes in other articles will be to "astronomy", not "astronomy and astrophysics". I disagree that "astronomy" is not science while "astrophysics" is. Of course astronomy is science!, otherwise we would have to include "astrology" with astronomy. It simply happens to be that astronomy is older than physics, and for a while it was not understood that all physics as studied on earth applies to the objects that astronomy studies. As late as late XIX century the was one philosopher (Comte, I think, but not sure) telling that astronomers would never know the chemical composition of the starts, and they had to limit themselves to observe positions and brightnesses (or something like that). So the realizing that you could, in fact, study the physics of objects revoluzionited astronomy, and expanded it. But that didn't "detach" astrophysics, as this new discipliene was called, from the rest of astronomy, it simply gave more depth to it. In short, yes, it is problematic to see what to put here. If there is not duplication with the astronomy page, there will be things missing. If there is duplication, well, there will be duplication. But, as I didn't create this mess (a relative term, as many won't think this is a mess at all), I won't try to solve it, and I exit the discussion having given my opinion...--AstroNomer 05:24, Jun 15, 2004 (UTC)

What happened in the 18th century in astrophysics? -- Karada 14:18, 10 Jun 2004 (UTC)

Not a lot. Astrophysics didn't become distinct from astronomy until people began studying the spectra of celestial objects in the 19th century. By the way, I've been trying to learn (or coin?) the name of a branch of astrophysics (I think), dealing with the rate at which more massive chemical elements are created and dispersed over time: see Talk:Kinetics. --Arkuat 02:12, 2005 July 17 (UTC)

[edit] Vote

I agree with recombining. If it is too long, there must be a better way to split it. How about making history of astronomy one page and astronomy and astrophysics the other. Or if not that, then before and after the year 1900. That sort of corresponds to the modern physics period. --David R. Ingham 21:54, 9 August 2005 (UTC)

[edit] History

[edit] Galileo

", but in astronomy his observation did not have astrophysical significance." You mean his laws of motion experiments didn't yet. They contributed to classical mechanics, and therefore to explaining Kepler's laws. --David R. Ingham 21:21, 9 August 2005 (UTC)

[edit] Images

The usage of the image of a galaxy doesn't seem right to me.. While it might be on the cover of an astrophysics textbook, it doesn't illustrate the concept of astrophysics at all. IMO, images of the cosmos belong in Astronomy, diagrams and things belong in astrophysics. —Snargle 01:31, 6 September 2005 (UTC)

[edit] Stellar structure

One of the biggest astrophysical topics that seems to be almost completely missing from this page is the very successful model of stellar structure for main sequence stars. The model includes hydrostatic equilibrium, thermal equilibrium, opacity, energy transport (conduction, convection, and radiation), and, of course, energy production. The Stellar structure page only has a weak coverage of this topic. Thanks. :) — RJH 17:43, 9 September 2005 (UTC)

[edit] Astrodynamics; choice of topics?

I feel as though celestial mechanics is classified as a branch of Astrophysics. Regarding to this, I don't understand why it should have its own section; also the article should be formulas-free as this is supposed to be an introductory article.

I think that a good thing to do would be to create a 'research topics', listing the most prominent topics that are object of theoretical research, linked to the appropriate page and divided in four main chunks. ie:

  • Star and stellar populations: Stellar evolution, Stellar structure, Variable stars, Globular clusters, Pulsars, Extrasolar planets...
  • Extragalactic: Galaxy formation, Galaxy evolution, Galactic dynamics, AGN, Cluster of galaxies...
  • Cosmology: Universe models, CMB, Dark matter, Dark energy...

Lipschitz 17:26, 7 January 2006 (UTC)

I think that astrodynamics (celestial mechanics) is not just a branch of astrophysics. i have taken upper-level courses in both and neither even overlap material.

Dpu2002 17:42, 5 June 2006 (UTC)

[edit] GA nomination

I took this article off the good article nominations page as I feel it fails the criteria - it omits major facets of the topic by being extremely brief. The theoretical astrophysics section, for example, consists of one sentence and a list. Worldtraveller 21:40, 22 April 2006 (UTC)

[edit] Pre-Aristarchus?

"This idea had been around, though, for nearly 2000 years when Aristarchus first suggested it, but not in such a nice mathematical model." -- tantalizing, but no citation. Can someone be more specific? David Brooks 02:54, 24 June 2006 (UTC)

[edit] Inappropriate Content

The paragraph in the 'Theoretical Astrophysics' section
'Within the astronomical community, theorists are widely caricatured as being mechanically inept and unlucky for observational efforts. Having a theorist at an observatory is considered likely to jinx an observation run and cause machines to break inexplicably or to have the sky cloud over'
is in my opinion inappropriate for an encyclopedia and should be removed.
Thomas —The preceding unsigned comment was added by 81.107.80.92 (talk) 10:18, 6 December 2006 (UTC).

[edit] Merge notice

Please see the discussion at Wikipedia Talk:WikiProject Astronomy#Merging astronomy and astrophysics. Dr. Submillimeter 23:00, 14 June 2007 (UTC)

[edit] Turn into redirect for astronomy

It looks like this could be turned into a redirect for astronomy at this point. Most of the useful non-duplicative material was moved to astronomy. I will do this on 25 Jun 2007 unless I receive strong objections. Dr. Submillimeter 13:44, 22 June 2007 (UTC)

Good idea. Until(1 == 2) 14:16, 22 June 2007 (UTC)
I know this is somewhat late, but historically the fusion of astronomy with astrophysics is rather recent, since astrophysics itself (as a field of study) is of much more recent origin than astronomy. The history of astronomy extends back into prehistory, but the history of astrophysics is rooted in the discovery of spectral lines by Fraunhofer and others. From that time, only 200 years ago or so, until the development of quantum mechanics only 75 years ago, the fields were completely distinct. I think a short separate article about the subject matter that has historically been specific to astrophysics and distinguished from astronomy as a whole might be better than a simple redirect. There is a distinction to be drawn, even now, and the specifically astrophysical content tends to get lost in the (already very large) article on astronomy. I propose reverting the redirect, and shortening and simplifying the article on astrophysics as it stood at the time the redirect was made. --arkuat (talk) 08:01, 21 July 2007 (UTC)

Actually, it could be argued that the fusion of astronomy with astrophysics started with Isaac Newton, whose theories of physics were first applied to the motions of the planets. This assessment above is therefore incorrect. Moreover, the astronomy and astrophysics articles contained mostly redundant information anyway, so merging the articles made sense. Furthermore, this was extensively discussed in several locations (including Wikipedia Talk:WikiProject Astronomy before action was taken; reverting this would be disruptive. Finally, may I ask whether arkuat is a professional astronomer like I am? Is he really familiar with the field? If not, then perhaps he or she should rely on the professional advice of others. Dr. Submillimeter 08:25, 21 July 2007 (UTC)

[edit] November 2007

This merge looks as if it has not worked. With over 50 other languages still having separate articles for Astrophysics, and over 500 articles linking here, it looks as if there is not really a consensus for the redirect and that a large number of people see a distinction. Moreover, it has contaminated the Astronomy article, which now contains a POV description of why they could (implying should) be considered equivalent. The leading proponent of the redirect has left Wikipedia, making it difficult to discuss, so I think we should try restoring the earlier version and see whether this leads to an improvement. --Rumping 23:23, 11 November 2007 (UTC)

[edit] February 2008

The merge did work. The referenced information in astronomy clearly indicates that astrophysics is frequently used interchangably with astronomy. Moreover, a consensus was built up both here and at Wikipedia:Wikiproject Astronomy that the merge should go ahead.

The revert, however, did not work. The reverted article still contained no references to back up any of its statements about what it defined as astronomy. Anonymously, I left a tag indicating that the introduction (which could be considered controversial) was unreferenced. Nothing happened.

I also do not think that the astrophysics articles in other langauges (which are often poorly referenced or copies of the English-langauge Wikipedia) are a justification for keeping a factually incorrect article here. I also have not seen any discussion here or any effort by Rumping to discuss the reversion.

Therefore, I am reverting this article back to a redirect. Next time, please discuss the issue first, and please discuss the meaning of astrophysics with a professional astrophysicist. Dr. Submillimeter (talk) 18:25, 6 February 2008 (UTC)

I did raise it here on the talk page, on 11 November. The anon redirect was reverted in December [1], not by me, suggesting you are nowhere near a consensus. Even your own paragraphs give references showing that astrophysics is a branch of astronomy.[2] And if neither the early history of astronomy nor modern amateur observational astronomy are astrophysics and there are a huge number of incoming links to Astrophysics then there really is not a good reason to merge, . --Rumping (talk) 09:55, 9 February 2008 (UTC)

Please come join the discussion over on the astronomy project page. WilliamKF (talk) 18:02, 13 February 2008 (UTC)

[edit] March 2008

Also, I have put a subsection in the Wikipedia talk:WikiProject Astronomy article under the Essence of astronomy section that tries to clarify the distinction for incoming readers:

Relation to astrophysics
The subjects of astronomy and astrophysics are very large and closely related, too overlaid and intertwined in almost all their branches for either to be considered subordinate to the other. Astronomy is the ancient subject, concerning the observations of bodies beyond the Earth (and also with timekeeping and calendar maintenance), together with the meaning of those observations and our understanding of the nature of those bodies. Astrophysics is much more recent. The basic understanding of the movement of celestial bodies, and its essential connection with earthly natural science, or physics, dates from the work of Galileo and Isaac Newton. The realization that the light of stars could be analyzed for clues about their physical nature, such as mass, size, temperature, composition, age, and evolution, began with the development of optical spectroscopy in the mid-19th century.
Thus uninterpreted observation may be considered as closest to pure astronomy, whereas physical modeling of the Universe, from comets and asteroids to the Sun, planets and stars, to cosmology and the Big Bang, becomes more nearly "pure astrophysics" (if indeed such a subject exists apart from speculation) the more it is concerned with laboratory and theoretical physics, and the more detached from observation. As astronomy has taught us a great deal about physics, so has physics (and its related fields, from mathematics to chemistry, and perhaps soon to include biology) proved essential to our understanding of astronomy.

I worry that at least some sourcing is needed, for though I do happen to be "a professional astrophysicist" in some sense, this is not really enough. But consensus among other editors that it is at least going in the right direction would help. It seems to me that the definition given in this Astrophysics intro is fairly good. Wwheaton (talk) 00:00, 17 March 2008 (UTC)

[edit] Scientific Discussion - Astrophysics

http://www.intellecttoday.com/

IntellectToday is a place to discuss Astrophysics, as well as other scientific and philosophical subjects. IntellectToday has an extensive database related to Astrophysics and Astronomy, and considers it one of it's primary points of focus. —Preceding unsigned comment added by 71.181.181.118 (talk) 22:48, 27 March 2008 (UTC)