Geoscience Reference
In-Depth Information
them by friction. The Sun was embedded in a large vortex that acted by impulse on
the planets, carrying them in orbit; each planet is at the center of a smaller vortex,
transferring the rotation of the planet to any of its moons.
This concept of the way that the Sun and planets work produced a remarkably
prescient picture of the formation of the Sun that we might recognize as very modern.
If the Universe contained an immense number of vortices made up of particles of
various sizes, in time they would make dust by rubbing against one another and
would gather at the center of the vortex. This accumulation would become a star
like our Sun; other vortices would settle into planets. Planets that move from vortex
to vortex were recognizable as comets. All this is like the modern picture of the
formation of the Sun and planets from a rotating cloud of dust and gas.
The Cartesian theory of gravity could not produce Kepler's laws from the vortex
theory so it appeared second-best when compared to Newtonian theory in this way.
It was difficult to find a natural Cartesian formulation that predicted the shape of
the Earth (although the Academy awarded a prize to Bernouilli in 1734 for a paper
in which he presented a set of equations showing how the swirling whirlpools
would elongate the poles), and it is interesting that the fundamental philosophical
difficulty with “action at a distance” remained a problem for centuries after Newton
proposed it. In a way, though, the problem has been resolved by the General Theory
of Relativity, which talks of space being bent by gravity: space is more curved near
a body and this creates an orbit for bodies to follow as they pass by. The General
Theory, therefore, approaches towards the Cartesian theory of a plenum.
Voltaire explained the battle between the two theories of Newton and Descartes
in his
Letters from England
(1731):
A Frenchman who arrives in London will find philosophy, like everything else, very much
changed there. He had left the world a plenum, and he now finds it a vacuum. In Paris the
Universe is seen composed of vortices of subtle matter; but nothing like it is seen in
London. In France, it is the pressure of the moon that causes the tides; but in England it is
the sea that gravitates towards the moon; so that when you think that the moon should make
the tide flood with us, those gentlemen in England fancy it should be ebb. In the Cartesian
camp, everything acts by an impulse about which we understand not much; for M. Newton
it is all done by an attraction about which we understand not much more. In Paris, you think
of the Earth as a melon; in London it is flattened on both sides.
The last sentences refer to the shape of the Earth as delineated in the height of
the tides, with the pointy Earth shape providing a tide opposite to the theory of the
oblate Earth.
People
Voltaire (1694-1778)
Francois Marie Arouet, who called himself Voltaire, came to notoriety in Paris as a young
poet, writer and satirist. He enraged numerous enemies, suffering with dire consequences
(including imprisonment and beatings). In 1725, he went to London to escape the threats.
There he studied the differences between English and French sciences and philosophy,
especially political philosophy. Returning to Paris he wrote prolifically, moving to Prussia
and then Switzerland. He fled from city to city as the bitterness of his satire offended the
church (he was a militant atheist) and other authorities, as he took up causes against them.
At the age of 83 he was allowed to return to Paris, but after seeing the performance of his
final play, he died in 1778.
