Early Cosmology
- Introduction:
- the study of early Greek science is the study of
- the development and interactions of opinions concerning the method
for inquiry about "nature"
- the actual theories about "nature" and about natural phenomena
- All early societies had some technology (clay to pottery; agriculture,
writing); technological advances made when some could make the imaginative
leap necessary to appreciate the potential of a new substance and how
to exploit it. E.g., clay to pottery; mould to penicillin. Experimentation
not to test a theory, but to improve a product.
- Characteristic of all technical and "scientific" treatises
in the Ancient Near East is the prevalence of magic. What does that mean?
- Some notable achievements:
- Egypt: a 365 day calendar. 12 months of 30 days each, but a five
day "celebration". That is a non lunar calendar.
- Babylonia: place-value notation; hexadecimal system. Extensive sets
of observations on the movements of the limited number of celestial
phenomena (esp. the planets and for religious purposes). Predictions
possible.
- The Basics of Early Greek Cosmology (650-400 BC)
- Constraints: At first...
- No concept of what we call "scientific method", tho that
will come later
- Lacked a language/vocabulary to formulate the problems
- Critical characteristics
- Clear and conscious distinction between the natural and the supernatural;
that is, natural phenomena not product of random or arbitrary (divine)
influence; divinity not denied, but not assumed to be active. Esp.
important in the investigation of unexpected natural phenomena like
earthquakes, lightning, eclipses.
- The practice of public debate. Within the context of public discussion
of political and legal matters of the city-state. More generally,
the early cosmologists, whether in Ionia (western Turkey) or in Sicily
knew about and critiqued each others theories. Demonstrates that such
speculation had a "popular" audience, one that extended
well beyond the invidual city-state to include the much of the Greek
work. This audience was interested in the discussion and transmitted
the concepts to others.
- Subjects of inquiry
- The explanation of unexpected natural phenomena:
earthquakes, lightning, rainbows, etc.
- the structure of the physical universe (kosmos).
The "Chicken Little Question": What holds up the sky? why
and how do the constellations progress? does the earth move? or does
the sun?
- Timeslines of the cosmologists
- Reconstructed systems:
- Homer: one perspective; a second
- Milesians: Anaximines; Anaximander
- Empedocles
- Texts to interpret: The Problem...How can one describe the and explain the
movements of the celestial bodies? Here are the some of the recorded statement
of three early cosmologists. Your task: to identify the following:
What problems concern them? What kinds of devises
to they use to explain change and movement, to account for the unexpected
event? So take your sheet of paper and record in separate columns
your thoughts on each of these two questions. Section II above may provide
guidance for this task.
- Structure of the cosmos
- from Anaxagoras
- The earth is flat in shape, and remains suspended because of
its size and because there is no vacuum. For this reason the air
is very strong, and supports the earth which is borne up by it.
- Of the moisture on the surface of the earth, the sea arose
from the waters in the earth (for when these were evaporated the
remainder turned salt), and from the rivers which flow into it.
- Rivers take their being both from the rains and from the waters
in the earth; for the earth is hollow and has waters in its cavities.
And the Nile rises in summer owing to the water that comes down
from the snows in Ethiopia.
- The sun and the moon and all the stars are fiery stones carried
round by the rotation of the aether. Under the stars are the sun
and moon, and also certain bodies which revolve with them, but
are invisible to us.
- We do not feel the heat of the stars because of the greatness
of their distance from the earth; and, further, they are not so
warm as the sun, because they occupy a colder region. The moon
is below the sun, and nearer us.
- The sun surpasses the Peloponnesus in size. The moon has not
a light of her own, but gets it from the sun. The course of the
stars goes under the earth.
- Empedocles
- '" Aetius says: "Empedocles held that there were two
suns: one, the archetype, the fire in one hemisphere of the world,
filling the whole hemisphere always stationed opposite its own
reflection; the other, the visible sun, its reflection in the
other hemisphere, that which is filled with air mingled with fire,
produced by the reflection of the earth, which is round, on the
crystalline sun, and carried round by the motion of the fiery
hemisphere. Or, to sum it up shortly, the sun is a reflection
of the terrestrial fire."
- "The moon was composed of air cut off by the fire; it was
frozen just like hail, and had its light from the sun." It
is, in other words, a disc of frozen air, of the same substance
as the solid sky which surrounds the heavens. Diogenes says that
Empedocles taught it was smaller than the sun, and Aetius tells
us it was only half as distant from the earth.
- Empedocles did not explain the fixed stars by reflected light,
nor even the planets. They were made out of the fire which the
air carried with it when forced beneath the earth by the upward
rush of fire at the first separation. The fixed stars were attached
to the frozen air; the planets moved freely.
- "The moon was composed of air cut off by the fire; it was
frozen just like hail, and had its light from the sun." It
is, in other words, a disc of frozen air, of the same substance
as the solid sky which surrounds the heavens. Diogenes says that
Empedocles taught it was smaller than the sun, and Aetius tells
us it was only half as distant from the earth.
- Phenomena
- Anaxagoras
- The moon is eclipsed by the earth screening the sun's light
from it, and sometimes, too, by the bodies below the moon coming
before it. The sun is eclipsed at the new moon, when the moon
screens it from us. Both the sun and the moon turn back in their
courses owing to the repulsion of the air. The moon turns back
frequently, because it cannot prevail over the cold.
- Anaxagoras was the first to determine what concerns the eclipses
and the illumination of the sun and moon. And he said the moon
was of earth, and had plains and ravines in it. The Milky Way
was the reflection of the light of the stars that were not illuminated
by the sun. Shooting stars were sparks, as it were, which leapt
out owing to the motion of the heavenly vault.
- Empedocles
- Winds arose when the air was rarefied by the sun, and when things
were burned and made their way to the vault of heaven and were carried
off. Thunder and lightning were produced by heat striking upon clouds.
- Wind was explained from the opposite motions of the fiery and
airy hemispheres. Rain was caused by the compression of the Air,
which forced any water there might be in it out of its pores in
the form of drops. Lightning was fire forced out from the clouds
in much the same way.
- Earthquakes were caused by the air above striking on that beneath
the earth.
- Other and later cosmologists:
- Earthquakes: "...may be brought about both because wind
is caught up in the earth, so that the earth is dislocated in
small masses and is continually shaken, and that causees it to
sway." Epicurus
- Volcanoes: "Our theory (that air pressure causes earthquakes
and volcanoes) has been verified by actual observation. It has
been known that an earthquake has continued until the wind that
causeed it burtst through the earth into the air with the force
of a hurricane. This happened lately near Heracleia (on the Black
Sea). Here a port of the earth swelled up and lump like a mound
rose with noise: finally it burst, and a great wind came out of
it and through up live cinders and ashes." Aristotle.
- A Creation Story--note the similiarities and differences to the story
in Genesis: "Archelaus was by birth an Athenian, and the son of Apollodorus.
He spoke of the mixture of matter in a similar way to Anaxagoras,
and of the first principles likewise. He held, however, that there was a
certain mixture immanent even in Nous ("mind" or "intelligence"
that underlies the kosmos). And he held that there were two efficient causes
which were separated off from one another, namely, the warm and the cold.
The former was in motion, the latter at rest. When the water was liquefied
it flowed to the center, and there being burnt up it turned to earth and
air, the latter of which was borne upwards, while the former took up its
position below. These, then, are the reasons why the earth is at rest, and
why it came into being. It lies in the center, being practically no appreciable
part of the universe. (But the air rules over all things), being produced
by the burning of the fire, and from its original combustion comes the substance
of the heavenly bodies. Of these the sun is the largest, and the moon second;
the rest are of various sizes. He says that the heavens were inclined, and
that then the sun made light upon the earth, made the air transparent, and
the earth dry; for it was originally a pond, being high at the circumference
and hollow in the center. He adduces as a proof of this hollowness that
the sun does not rise and set at the same time for all peoples, as it ought
to do if the earth were level. As to animals, he says that when the earth
was first being warmed in the lower part where the warm and the cold were
mingled together, many living creatures appeared, and especially men, all
having the same manner of life, and deriving their sustenance from the slime;
they did not live long, and later on generation f rom one another began.
And men were distinguished from the rest, and set up leaders, and laws,
and arts, and cities, and so forth. And he says that Nous (intelligence)
is implanted in all animals alike; for each of the animals, as well as man,
makes use of Nous, but some quicker and some slower."
- Why in Greece? Why in Ionia? and why at this time?
