1 The Birth of Science - MSRI

11.7 Newton’s Natural Philosophy 327
or a mass of liquid swinging about the center of the earth. The ancient
testimonia discussed in Chapter 10 and the use made of them by Kepler,
Newton and others show that this leap was achieved only once in history:
in Hellenistic science.
Two sets of factors were essential in creating the conditions for a modern
gravitation-based dynamics to take shape as a scientific theory and evolve
into modern physics.
The first set consisted of certain Hellenistic technical and methodological
tools, found above all in the works of Euclid and Archimedes. Some of
these tools were:
– the hypothetico-deductive method created in the Elements, providing
the general conceptual framework to which there must conform any
scientific theory wishing to use the results of classical mathematics — a
use that is of course inescapable;
– the so-called “method of exhaustion”, whose relation to the seed of infinitesimal
analysis developed by Newton will be discussed in the next
section;
– Archimedean mechanics, as laid out specifically in the treatise On the
equilibrium of plane figures, which showed how to use the preceding
methods to found a scientific theory of mechanics.
The second set of prerequisites were certain pieces of information on
dynamics and gravitation which, with the loss of the original treatises,
were found scattered throughout works generally written by scientifically
incompetent authors and representing traditions that were far from scientific.
The fragmentary and heterogeneous nature of these testimonia
makes their complete identification difficult. Based on an examination of page 402
a small part of the still extant literature, one can list at least the following
examples.
– The hints about inertia, centrifugal force and gravity (toward the earth)
transmitted by Plutarch in the De facie. These hints included a few “exercises
in dynamics” together with their qualitative answers. 129
– Other hints complementary to the first, including those found in the
commentaries to Aristotle by Simplicius and Philoponus and in the
Heronian and pseudo-Aristotelian Mechanics.
– Mentions of an attraction between planets and sun, and of the use of
this idea in a heliocentric framework to create a “celestial mechanics”
129 Sambursky (who was first and foremost an experimental physicist) revealingly wrote that
“some of [the conclusions in the De facie] call to mind classic exercises from Newton’s Theory
of Gravitation”: see [Sambursky: PWG], p. 209. Yet he did not consider the question of the dialog’s
sources, taking it to be “perhaps the first work in astrophysics ever written” (p. 205) — which
would make Plutarch the founder of that science!
Revision: 1.11 Date: 2003/01/06 07:48:20