Sections
In truth at first Chaos came to be, but next wide-bosomed Earth, the ever-sure foundation of all the deathless ones who hold the peaks of snowy Olympus, and dim Tartarus in the depth of the wide-pathed Earth, and Eros (Love), fairest among the deathless gods, who unnerves the limbs and overcomes the mind and wise counsels of all gods and all men within them. From Chaos came forth Erebus and black Night; but of Night were born Aether and Day, whom she conceived and bore from union in love with Erebus. And Earth first bore starry Heaven, equal to herself, to cover her on every side, and to be an ever-sure abiding-place for the blessed gods. And she brought forth long hills, graceful haunts of the goddess Nymphs who dwell amongst the glens of the hills. She bore also the fruitless deep with his raging swell, Pontus, without sweet union of love.
Translation: Hugh G. Evelyn-White (1874--1924). See Perseus Digital Library: Hesiod's Theogony, line 104--
But the ancient Greek astronomers did NOT put the pieces together and neither did the Medieval astronomers.
But in theoretical astronomy, western Eurasia was stuck in the mire of the double astronomy of Aristotelian cosmology (see Aristotelian cosmology cartoon) and the Ptolemaic system (see Ptolemaic system cartoon).
Isaac Newton (1643--1727) only speculated a little and inconclusively on the structure of the universe and what held it up against self-gravity.
By the way, the Principia (1687) is an awful book.
Olbers' paradox is strong evidence against an infinite, eternal, static universe full of stars.
It was a great idea, but he was defeated by interstellar dust.
And he was a composer: William Herschel (1738-1822) - Symphony No 12 in D Major, 2nd movement 4:26--11:30.
Sir Christopher Wren's (1632--1723) speculation:
Sir Christopher Wren's (1632--1723) speculation had NO historical impact, but shows even before Newtonian physics that at least someone could speculate on a universe full of galaxies in addition to one full of stars.
Others in the 18th century speculated on other galaxies: the architect Thomas Wright (1711--1786), the philosopher Immanuel Kant (1724--1804), the mathematician Heinrich Lambert (1728--1777), and William Herschel (1738--1822).
Below is Lord Rosse's (1800-1867) drawing from visual astronomy of the Whirlpool Galaxy (AKA M51a/NGC 5194 and M51b/NGC 5195) in constellation Canes Venatici in 1845.
Qualitatively, Lord Rosse (1800-1867) didn't do too badly.
It classifies spiral galaxies, elliptical galaxies, lenticular (S0) galaxies, and irregular galaxies.
It's ironic to think that an extremely important true result was accepted as such while unknown large systematic error weakened original evidence on which it was accepted.
Einstein universe (1917) is, in fact, a Friedmann-equation (FE) model discovered without using the Friedmann equation (FE, 1922).
For this to be true, general relativity had to apply to the universe as whole.
Newtonian physics does NOT do this without extra hypotheses.
It just has the cosmological constant Λ.
It is also infinite and eternal---it's been expanding emptily forever and always will.
But the de Sitter universe (1917) did predict the expanding universe and the cosmological redshift.
It also predicted Hubble's law, but no one seems to have noticed that explicitly.
In the ideal, Friedmann equation (FE) model, all lengths scale with cosmic time by the cosmic scale factor a(t):
The Einstein universe (1917) and de Sitter universe (1917) are Friedmann equation (FE) models discovered by klutzy means before the discovery of the Friedmann equation (1922).
What is the Friedmann equation (1922)?
The Friedmann equation (1922) describes the dynamics of the universe as whole.
Lemaitre independently discovered the Friedmann equation (1922) in 1927. None other than Albert Einstein (1879--1955) informed him that it was a rediscovery in 1927 (see MacTutor: Georges Lemaitre (1894--1966)).
However, Lemaitre explicitly discovered (as Alexander Friedmann (1888--1925) did NOT) Hubble's law as a necessary consequence of the Friedmann equation (1922).
This was a theoretical discovery of a consequence of the Friedmann equation (1922), NOT an empirical discovery that the observable universe obeyed Hubble's law.
However, Georges Lemaitre (1894--1966) did deduce a value for the Hubble constant based on published data that was only somewhat worse than Edwin Hubble (1889--1953) own value from 1929.
But this was NOT a proof that Hubble's law applied to the observable universe.
No one much noticed Georges Lemaitre (1894--1966) work in 1927 since he published in French and was published only in the obscure Annals of the Scientific Society of Brussels.
Except Albert Einstein (1879--1955)---who didn't think much of it at that time.
Hubble's value for the Hubble constant was really bad: i.e., ∼ 500 (km/s)/Mpc.
This suggested a characteristic age for the observable universe of order 2 billion years.
But circa 1930, the Earth was already known to be of order 3 billion years from radioactive dating.
So there was an AGE PROBLEM which was only finally resolved when the Hubble constant was revised to 50--100 500 (km/s)/Mpc after circa 1950.
In the 1930s, most cosmologists---of whom there were maybe 10---thought nothing of this.
But Georges Lemaitre (1894--1966) presented his primeval atom origin in 1931--1933 which is a "cold big bang theory" as a part of what we can call the the Lemaitre universe (1933)---an ingenious theory that turned out to be wrong---and probably did NOT excite as much interest as it should have had in the 1930s.
George Gamow (1904-1968) and his colleages Ralph Alpher (1921--2007) and Robert Hermann (1914--1997) (who knew a lot more about nuclear physics than the other George---Georges Lemaitre (1894--1966) proposed for near the mythical point origin:
They is unbelievable, but so is the universe.
The cosmic microwave background (CMB) is one of the strongest proofs of the Big Bang theory: there is NO other plausible explanation for cosmic microwave background (CMB) given all the other constraints of the observable universe.
The cosmic microwave background (CMB) was discovered fortuitously in 1965 by Arno Penzias (1933--) and Robert Wilson (1936--).
Very likely, but ...
It seems almost always case, you see one new paper saying how the Lambda-CDM model fails their test by 3 or 4 sigma and then the next new paper says how the Lambda-CDM model is consistent with their test.
Obviously, the Lambda-CDM model is just a very good discription of the observable universe to within a few percent loosely speaking.
Finding a new cosmological model that fits everything to within tenths of a percent and maybe is fundamentally true is a challenge.
What are the possible new cosmological models?
They are quasi endless and all over the place.
Which if any of them are right is a hard question.
But more data (exabytes of it) is on the way.
More below on more data.
The inflaton.
One assumes general relativity applies to the whole multiverse, and so maybe the multiverse is in overall expansion or contraction.
But is the gravitational constant G = 6.67430(15)*10**(-11) (MKS units) the same throughout the multiverse?
They should also put much tighter constraints on structure formation (AKA large-scale structure formation).
Exabytes of new data will become available.
Alas, all the information will have to be pulled out of the data by statistics.
Ernest Rutherford (1871--1937) once said if you need statistics, you are doing the wrong experiment.
To gloss his aphorism, you should do the decisive experiment.
The information from statistics is all we have it seems.
The new spacecraft missions: