Physical cosmology...
Physical cosmology (often simply described as 'cosmology') is the scientific study of the universe, from the beginning of its physical existence. It includes speculative concepts such as a multiverse, when these are being discussed. In physical cosmology, the term cosmos is often used in a technical way, referring to a particular spacetime continuum within a (postulated) multiverse. Our particular cosmos, the observable universe, is generally capitalized as the Cosmos.
In physical cosmology, the uncapitalized term cosmic signifies a subject with a relationship to the universe, such as 'cosmic time' (time since the Big Bang), 'cosmic rays' (high energy particles or radiation detected from space), and 'cosmic microwave background' (microwave radiation detectable from all directions in space).
According to Charles Peter Mason in Sir William Smith Dictionary of Greek and Roman Biography and Mythology (1870, see book screenshot for full quote), Pythagoreans described the universe.
Excerpt from Philolaus Pythagoras book, (Charles Peter Mason, 1870)
It appears, in fact, from this, as well as from the extant fragments, that the first book (from Philolaus) of the work contained a general account of the origin and arrangement of the universe. The second book appears to have been an exposition of the nature of numbers, which in the Pythagorean theory are the essence and source of all things.
Religious cosmology...
In theology, the cosmos is the created heavenly bodies (sun, moon, planets, and fixed stars). In Christian theology, the word is also used synonymously with aion[8] to refer to "worldly life" or "this world" or "this age" as opposed to the afterlife or world to come.
The 1870 book Dictionary of Greek and Roman Biography and Mythology noted
Thales dogma that water is the origin of things, that is, that it is that out of which every thing arises, and into which every thing resolves itself, Thales may have followed Orphic cosmogonies, while, unlike them, he sought to establish the truth of the assertion. Hence, Aristotle, immediately after he has called him the originator of philosophy brings forward the reasons which Thales was believed to have adduced in confirmation of that assertion; for that no written development of it, or indeed any book by Thales, was extant, is proved by the expressions which Aristotle uses when he brings forward the doctrines and proofs of the Milesian.
Plato, describes the idea of the good, or the Godhead, sometimes teleologically, as the ultimate purpose of all conditioned existence; sometimes cosmologically, as the ultimate operative cause; and has begun to develop the cosmological, as also the physico-theological proof for the being of God; but has referred both back to the idea of the Good, as the necessary presupposition to all other ideas, and our cognition of them.
The book The Works of Aristotle
Aristotle says the poet Orpheus never existed; the Pythagoreans ascribe this Orphic poem to a certain Cercon (see Cercops).
Bertrand Russell (1947) ...
The Orphics were an ascetic sect; wine, to them, was only a symbol, as, later, in the Christian sacrament. The intoxication that they sought was that of "enthusiasm," of union with the god. They believed themselves, in this way, to acquire mystic knowledge not obtainable by ordinary means. This mystical element entered into Greek philosophy with Pythagoras, who was a reformer of Orphism as Orpheus was a reformer of the religion of Dionysus. From Pythagoras Orphic elements entered into the philosophy of Plato, and from Plato into most later philosophy that was in any degree religious.