Physics by Aristotle

Author:Aristotle [Aristotle]
Language: eng
Format: epub, pdf
Tags: Non-Fiction, Philosophy, Science
ISBN: 9781481274623
Google: QpGlDEJUDVAC
Amazon: 1481274627
Goodreads: 366330
Publisher: Libre Dionysia
Published: 2020-08-13T04:00:00+00:00

9. The true explanation of compression and expansion

Some people, however, think that the existence of void is clearly shown by the existence of rarity and density: without rarity and density, compression and contraction are impossible too; but if they are impossible, either change will be eliminated altogether, or the universe will bulge (as Xuthus[263] said), or there must be no loss or gain during change† (for instance, if some air comes from a ladleful of water, then an equal volume of air must at the same time generate the same amount of water), or there has to be void (because without void, the argument goes, it is impossible for compression and expansion to occur).

Now, if by ‘rare’ they mean ’that which has a plurality of separated voids within itself’, it is clear—given that there can no more be separable void than there can be place with its own extension—that this sense of ‘rare’ is ruled out. The alternative—that something rare does contain void, but not separable void[264] —is more plausible, but it still entails, first, that void is not responsible for all movement, but only for upward movement (since anything rare is light, which is why fire is said to be rare), and, second, that void is not responsible for movement in the sense that it is that in which movement happens. Rather, it carries things upwards in the same way that wineskins,[265] when lifted upwards, carry with them what is continuous with them. And yet how can void move or have a place? The place to which it moves would have to become void of void.[266] Moreover, how will they explain the downward movement of heavy things? Also, if the more a thing is rare and void, the faster it will move upwards, it is clear that nothing would move faster than something which is entirely void. But it is also possible that this absolute void cannot move. The same argument applies: just as everything in a void is immobile, so the void too is immobile, because the speeds are incomparable.[267]

Although we deny that there is such a thing as void, the rest of the difficulties do genuinely arise: if condensation and rarefaction do not happen, then either change will be ruled out, or the universe will bulge, or when air comes from water an equal amount of water will always come from air (since obviously the volume of air produced is greater than the volume of the water it came from). If there is no such thing as compression, then, it necessarily follows either that when things are pushed outwards, one after another, the last thing will make a bulge (this is a consequence of any change of place, unless the motion is circular; but movement goes in straight lines as well as in circles),† or that somewhere else in the world some air is changing into an equal amount of water so that the total volume of the universe as a whole remains constant, or that nothing is changing.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.