[HN Gopher] Notes Regarding Dupuis' 1910 Elements of Astronomy [...
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Notes Regarding Dupuis' 1910 Elements of Astronomy [pdf]
Author : mymythisisthis
Score : 81 points
Date : 2021-08-31 15:09 UTC (18 hours ago)
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(TXT) w3m dump (gron.ca)
| codethief wrote:
| Speaking of astronomy books, I wish there were a (history of)
| physics book that would not assume any prior knowledge about
| astronomy or cosmology on the reader's part and slowly build up
| the (currently accepted) theories of cosmology and astrophysics,
| starting from "See those bright spots on the sky? We call those
| 'stars' and we have reasons to believe that they are similar in
| nature to our sun because [...]." to "This is how we measure
| distances (assuming a flat background) to _nearby_ stars "[00] to
| "This is how we know what the Milky Way looks like and that there
| are other galaxies outside ours[0]" to "This is why we are
| convinced that the universe at large scales is best described by
| an FLRW spacetime with cosmological constant > 0 and there was a
| Big Bang et cetera".
|
| The issue is that, ultimately, the only thing we can observe is
| electromagnetic waves[1], characterized by frequency,
| polarization and intensity, and originating from some point on a
| 2D sphere. _Everything else_ is interpretation[2]. So cosmology
| today consists of dozens of layers of interpretation stacked upon
| one another and for me (as a mathematical physicist who once
| dabbled in cosmology but is ultimately an outsider to the field)
| it 's hard to keep track of all the assumptions and the causal
| chains of observations and interpretations that are implicit in
| today's widely accepted results.
|
| To give an example, people say that the universe is expanding and
| they point to redshift (~ (apparent) velocity) measurements such
| as those done by Hubble. Great, but how do you measure redshift
| as a function of distance if all you see is a 2D sky and you
| can't "see" the axis parallel to your line of sight? You
| introduce various distance measures like angular distance and
| luminosity distance which are based upon the notions of standard
| rulers and standard candles. But these are not exactly trivial to
| get right, either[3], and AFAIU rest upon an entire body of
| theories from astrophysics and plasma physics. Plus, there are
| countless of things that can happen to electromagnetic waves on
| their way to Earth (absorption, gravitational lensing, Sachs-
| Wolfe effect, ...) and you must account for those, too.
|
| Don't get me wrong. I'm not trying to cast doubt on any of the
| currently accepted theories. _Not in the least_. Nor is the
| particular example above not well-understood. I 'm just saying
| that, for an outsider, it's not easy to follow the chain of
| implications sometimes and many books don't do a very good job of
| logical bookkeeping. A book painting the architecture of the
| Standard Model in broad but logically accurate strokes would go a
| long way.
|
| Meanwhile, I notice reruns of "Through the Wormhole" on TV every
| other year with Morgan Freeman going on about hypotheticals like
| string theory, parallel universes and such, while completely
| foregoing the (well-established but IMO still exciting) "basics".
| It's almost physically painful to imagine what _additional_
| confusion this must cause the layman that knows barely anything
| about physics in the first place. _Any sufficiently advanced
| physical theory is indistinguishable from magic_ comes to mind.
|
| [00] See the conundrum there?
|
| [0] https://en.wikipedia.org/wiki/Galaxy#Observation_history
|
| [1] and some ionized radiation, and now of course gravitational
| waves.
|
| [2] "Everything is interpretation" not in the esoteric sense but
| of course in the sense that we draw logically stringent
| conclusions based upon already well-established physical
| theories.
|
| [3]
| https://en.wikipedia.org/wiki/Cosmic_distance_ladder#Problem...
| gshubert17 wrote:
| Isaac Asimov's _Understanding Physics_ is older (1966) but is
| meant for the general reader or to supplement a textbook. It
| uses algebra and only a little trig.
|
| J. D. Bernal's _A History of Classical Physics_ (1972) begins
| with ideas from ancient Greece and goes to the end of the 19th
| century. No math, but lots of pictures and diagrams. I have a
| 1997 reprint.
|
| Stephen F. Mason's _A History of the Sciences_ (1962) covers
| chemistry and biology as well as physics, from Babylonia and
| Egypt to the mid twentieth century.
|
| I am sure there are many others, but these, which include
| history and biography as well as scientific content, are good,
| readable overviews.
| Trombone12 wrote:
| The Earth by Hubert Krivine (ISBN:978-1-78168-799-4) does
| exactly this for the case of the Earths age and motion around
| the Sun, so that's a start.
|
| If your ambition is a more detailed history of science account
| of the establishment of the distance ladder (up to some
| slightly distant point in time, as work is still ongoing, see
| the famous Hubble tension), try googling for articles about
| history of science and the distance ladder. That activity gives
| me this preview that might be interesting:
| https://www.jstor.org/stable/24536521
|
| A full version can probably be found online.
| mymythisisthis wrote:
| That's why I really like Dupuis's 1910 textbook. Gets the right
| amount of basic information and math.
|
| I'd really like to see how Newton, Kepler or Copernicus went
| about making their calculations, step by step. Break it down
| point by point to make it understandable without skipping
| steps. Like to see how Ptolmey constructed the star table.
|
| Too many science books are either popular in nature with no
| math, or for someone doing a masters in the field. I guess
| there is not a large enough audience of people in the middle to
| justify writing such books.
| [deleted]
| antognini wrote:
| This is a bit of a shameless plug, but I'm an astronomer who
| has been interested in these kinds of questions for a long time
| and earlier this year started a podcast to delve into answering
| them. It's a history of astronomy starting with the Babylonians
| and working towards modern astronomy (though at one episode a
| month it will take a while to get all the way through).
|
| My intention has been to take the astronomy of each era on its
| own terms and try to understand what questions they were trying
| to answer and what techniques they used to answer them. You
| tend to read things like "the Ptolemaic system was geocentric
| and had to use lots of epicycles to work and then 1500 years
| later Copernicus introduced a heliocentric system that didn't
| need epicycles." but I'm trying to explain _how_ these systems
| developed, why epicycles seemed to be natural, how they figured
| out what epicycles were needed based on the observations they
| had made, etc.
|
| The website is here if you're interested: www.songofurania.com
| mymythisisthis wrote:
| This was a good read
| https://archive.org/details/historyofplaneta00dreyuoft
| History of the planetary systems from Thales to Kepler by
| Dreyer
| a9h74j wrote:
| It is worth remembering that we are barely 100 years from the
| time in which the notion of galaxies was not common. The textbook
| itself discusses Nebulae near the end, in all of 2--3 pages.[1]
|
| From p. 199: It was consequently thought, at once, that all
| nebulae might be shown to be star clusters under sufficiently
| high powers of the telescope. But the spectrascope has shown that
| such an inference is untenable, as the spectra of the two things
| are quite different, and that the spectrum of a nebula contains a
| line which is found nowhere else, and which is attributed to some
| substance called _nebulum_ , and which is totally unknown
| anywhere except in a nebula.
|
| I propose we adopt _neo-nebulum_ as a more neutral term than dark
| matter!!
|
| [1]
| https://archive.org/details/cu31924031322203/page/n213/mode/...
| handrous wrote:
| What ended up being the cause of that mysterious spectral line?
| ericbarrett wrote:
| Double-ionized oxygen: https://en.wikipedia.org/wiki/Nebulium
| handrous wrote:
| Ha! Didn't occur to me to search the archaic name on
| Wikipedia, but in hindsight, of course that works.
| Trombone12 wrote:
| Other 1910 astronomy questions: how do star work? How are they
| powered? Do they just cool forever from their birth? Do they
| contract to the point of becoming liquid?
| ianmcgowan wrote:
| There are some great anti-flat earth examples in here - digging
| canals having to drop 8" per mile is obvious when you think about
| it. Objects being heavier at the poles and pendulums running
| faster because the earth is oblate, not a perfect sphere is also
| a clever illustration.
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