Expert: Jayendra Upadhye - 10/20/2004

Question
Why did the Greek astronomers conclude that the heavens were made up of perfect spheres moving at constant speed?

Answer
Hi kima,
I suggest you read 2 books Cosmos by Sagan and Asimov's Bible.
Each has meticulously and (humorously) put forward "why" ANCIENT PEOPLE thought thus.
It appears the greeks were (like the Indians) rather obsessed by the fact that everything "earthly" was imperfect and all the rest perfect, hence inaccessible to "corrupt" man.
Also they loved somehow to reach simplistic answers...like
everything god made had to have "whole numbers" associated with it.
like existence is made of "5" principles
1 - solidity
2 - liquidity as in water
3 - heat
4 - fluidity as in gases
5 - space or absence of above 4 (especially hindu concept called aakash from which in the end "shoonya" or conecpt of zero emerged.
Like wise the greeks thought since a sphere is the most perfect physical form, the sky is indeed a hollow sphere!
Afterall all the stars appeared to be "same distance" "somewhere out there" on a "perfect" (for it was unreachable by man) sphere or set of spheres.
(if you assigned one sphere for each planet and the final collective one for the stars)
The indians had their "three" divisions:-
1 - prithvi or the earth
2 - Du-lok (pronounced due with soft d) which is the world between earth and sky or our atmosphere.
3 - Aakash or space.
and the 5 great aspects of being the "pancha (5) maha (great) bhuta (those that have existed)" already enlisted above.
then they had the tri-kaal or 3 aspects of time past-present and future (obviously still correct)!
and the 5 pranas (driving forces) of life in all bodies
- Pan, Apan, Vyan, Udan and Saman
It appears fractions eluded them completely untill the much later invention of the zero.
Jayen