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2 ideas
20964 | Descartes said there was conservation of 'quantity of motion' [Descartes, by Papineau] |
Full Idea: Descartes incorporated the conservation of what he called 'quantity of motion', by which he meant mass times speed. | |
From: report of René Descartes (The World [1631]) by David Papineau - Thinking about Consciousness App 2 | |
A reaction: Mass times velocity is now called 'momentum'. Is this the first ever conservation law? There are now lots of them. |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |