[Avodah] mabul

[Micha Berger]

On Thu, Nov 03, 2011 at 12:34:43PM -0400, Zev Sero wrote:
> Not all the Amora'im knew the earth was round, but the Tana'im knew it.

The dominant belief in the Roman Empire was the Ptolemeic universe. The
earth in the center, with orbiting transparent shells around it
("galgalim") that had the moon, sun and planets in them, and a final
solid shell that held numerous stars.

The Babylonians believed that the sky is a semi-spherical shell ("raqia")
above the planet. Under the Sassanids, the Ptolemeic model slowly gained
currency. And the mazalos are not attached to the dome, they move on their
own -- just like the kokhavei lekhes.

Among Chazal....

I don't share RZS's confidence that the line was between tannaim and
amoraim.

Both R' Eliezer and R' Yehushua both describe the flood (RH 11b) as
falling through the heaven onto the earth. Rebbe (Pesachim 94b) is
described as arguing against the ages of Rome when he said the mazalos
move and the galgal is fixed (which was the Babylonian theory). So there
were tannaim who didn't buy into Ptolemy.

Among amoraim as well (in agreement with RZS): Pesahim 94b and Y-mi
Berakhos 1:1 (3a-4b) both discuss the time it takes for the sun to go
from inside to behind the sky at sunset. The gemara in Pesachim revolves
around R' Yehudah, R' Chanina, and other Israeli names, so maybe it can't
testify about belief in Bavel. But in Chagiga 15a there is an explicit
description of the sky as a lid that toughes, or almost touches, the
earth at its edges. A couple of blatt earlier (12b) we were told that
the world floats on the tehom, or is held above it by pillars.

Although we do have a beraisa that proves that the sun goes under the
earth because the polls heat up at night, this also rules out believing
the earth is a globe. If it were a globe with the sun orbiting around it,
the sun at night would be further from those pools than it is during
the day by the diameter of the planet! And that beraisa appears as a
proof cited by R' Chiya -- an amora who clearly believed in neither of
the two models I gave on top. It's as though he heard something about
Ptolmey (orbits), but not the full idea.

Ptolemy does reach chazal, and we find that the amoraim of EY adopted that
astronomy before those of Bavel.

The conclusion I drew when I did a more complete survey (lost somewhere
in a 1990s mail-jewish archive) was that Chazal were on the conservative
side of the trend in the natural philosophy community, but did simply
follow the theories of that community.

Tir'u baTov!
-Micha

-- 
Micha Berger             When a king dies, his power ends,
micha at aishdas.org        but when a prophet dies, his influence is just
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