Shifting Pictures of the Universe
Below is an example of one kind of the many kinds of traditional
representations of the universe and of time: the snake swallowing its
tail. It is a symbol that one finds all
over the world.
A. Traditional Uroboros (snake swalllowing its tail)
This is a representation of the cosmos of the ancient Near East, the Genesis cosmos. It is a three part picture: the heavens, the flat earth, the
underworld. As it is described in Genesis, God separated the waters,
providing a space. The firmament held
up the upper waters, making space for dry land where animals, plants, and
people could find a home. But the firmament
had the possibility of breaking, and in the Noah story, the chimneys in the
firmament and the fountains of the deep open up. The Flood was understood as not just a rainstorm but a cosmic
catastrophe, a threat to recreate the primordial chaos.
The Medieval picture is based on the Ptolemaic and even earlier
Platonic and Aristotelian conceptions of the crystalline spheres, with the
spherical earth at the center and the whole pattern of spheres revolving around
the earth every day. The spheres also
revolve slowly against each other. The
innermost sphere carries the moon, and then Mercury and Venus and the sun (with
Mercury and Venus closely linked to the sun).
Beyond the sun were Mars, Jupiter, and Saturn (the Seventh Heaven), the
fixed stars, and then angels. This basic picture was reflected in many
ways in Medieval culture. For example
in a mystical Jewish Kabbalistic representation, there are also the ten
spheres, but the story is different. In
Lurianic Kabbalah God creates the universe by withdrawing from the center, a
process called Tzimtzum in
Hebrew. The ten spheres - or spherot, the numbers - represent the
emanations of God back into the universe.
Ein Sof - the infinite God
- surrounds all.
Galileos observations with
the telescope provided the first convincing evidence that the Ptolemaic picture
was wrong. This pulled the rug out from
the entire Medieval conception of a hierarchical structure of the universe -
including the human universe.
Galileos work, published in
Italy in 1610, spread quickly throughout Europe. Already in 1611 in England John Donne writes:
The new Philosophy calls all in doubt,
The Element of fire is quite put out;
[the sphere of fire, the highest of the spheres below the lunar sphere, does
The Sun is lost, and thearth, and no mans wit
Can well direct him where to look for it...
Tis all in pieces, all coherence gone;
All just supply, and all Relation;
Prince, Subject, Father, Son, are things forgot...
Such was the impact of this change in cosmology.
What was the new
picture? The Newtonian cosmos replaced
the Medieval picture. There is simply
empty space, the void, stretching on indefinitely in all directions. In the Middle Ages, when one went out at night
and looked up, one saw majestic height, not infinite vastness. The statement in Pascals Pensees, the
eternal silence of these infinite spaces alarms me,is a sort of statement that one simply never encounters in Medieval writings. But it is a very common view once one is
living in the Newtonian universe - here represented by a work by Escher.
M.C. Escher's "Cubic Space Division" © 2002 Cordon Art B.V. - Baarn - Holland. All rights reserved.
Our modern conception bears some elements of all these pictures, but it
is very different from all of them. Let
me start by summarizing the differences between the Medieval, Newtonian, and
The Medieval cosmos is of finite size, it
began a finite length of time ago - which could be calculated by adding up the
begats in Genesis - and it was
geocentric. The physical part had to be
finite in size because the whole thing goes around once every day. Theres a distinction between the material
contents of the sublunar world and of the perfect, unchanging heavens.
The unifying ideas are constant circular motion and the Great Chain of
Being:hierarchy, continuity, plenitude. God
pervades the entire structure - or gods: pagan planetology coexisted with
Newton argued that if the cosmos were finite,
then everything would fall to the center,so it was probably infinite. But there
were paradoxes associated with this: Kepler had already pointed out that the
night sky would be bright as day in an everlasting infinite universe (Olbers
paradox). It also was not clear whether the Newtonian
universe was created a finite length of time ago. The unifying ideas were deterministic local mechanics and
universal gravitation: the laws of motion were the same on Earth as throughout
the universe. Gods role was the
creator of this clockwork universe at the beginning. For Newton at least, God also kept setting the clock right again
every so often.
In the modern cosmos, we know how big the
visible universe is, about 1028 centimeters (cm) - that distance is
called the cosmic horizon. We know
how long ago the universe started - about 14 billion years ago. We know that on large scales, It is
homogeneous and isotropic (the same in all directions). It is made of atoms, dark matter, and radiation. Gravity is curvature of spacetime and can
create horizons, and nondeterministic quantum mechanics and evolution are the
key ideas. It is not clear whether
there is a role for God.
Contributed by: Joel Primack and Nancy Abrams