1 The Birth of Science - MSRI

278 10. Lost Science
separated by large distances (in gases). 184 Melting and boiling and their inverses
were explained in terms of atomic motion. Several testimonia suggest
that temperature differences were understood to reflect changes in
atomic velocity: for example, Plutarch’s statement that the cold is merely
the absence of heat and that it has the property of being stationary, 185 and
the opinion, also refereed by Plutarch, that “hotter” means “faster”. 186
The path of an atom in a gas was thought of as being determined by a
continuing succession of collisions. 187 (The idea that gases are characterized
by chaotic atomic motion apparently fell into oblivion for centuries,
but it is peculiar that the word “gas” itself was coined in the seventeenth
century from the Greek term chaos, 188 which then, as in ancient times, had
many meanings.) Although we do not possess Philo of Byzantium’s theoretical
work on atomic motion in gases, we do find in his artillery book a
very interesting remark about the possible origin of randomness:
Many who have undertaken to build machines of equal size, using
the same structure, the same type of wood and the same metal,
not changing even the weight, have made some with long reach
and great destructive power and others far inferior; and if asked
why, they had no explanation. One might apply here the observation
made by the sculptor Polycletus, who said that the good [creation] is
obtained through many calculations, thanks to small differences. In
the same way in this techne [artillery design] many calculations are
needed, and someone who makes a small departure in the individual
parts causes a large error in the result. 189
In passing, we note that the use of mathematics to treat experimental
data was so entrenched that it was not discarded in this case in spite of the
unpredictable variability of concrete results. But the most interesting point
for us here is how an apparently random result is explained by means of
a chain of mathematical relations that magnify initially negligible variations:
essentially a mathematized version of the Stoic argument for reconciling
chance and determinism. This notion that “chance” can boil down
to small causes generating large effects seems to have been forgotten for
184
Epicurus, Letter to Herodotus, 43–44. The passage does not talk explicitly about solids and gases,
but this correspondence (more or less obvious, in any case) is spelled out in Lucretius, De rerum
natura, II, 95–111.
185
Plutarch, De primo frigido, 945F. See also Quaestiones naturales, 919A–B.
186
Plutarch, Quaestionum convivalium libri vi, 677E.
187
See for example Plutarch, Adversus Colotem, 1112B.
188
The neologism is due to J. B. van Helmont (1577–1644), who used a Flemish phonetic equivalent
for the letter . I am grateful to F. Bonelli for bringing this etymology to my attention.
189
Philo of Bizantium, Belopoeica, 49, 13 – 50, 9 = [Marsden: TT], pp. 106–107.
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