Editing Blaise Pascal (section)

===Vacuum===
By 1647, Pascal had learned of [[Evangelista Torricelli]]'s experimentation with [[barometer]]s. Having replicated an experiment that involved placing a tube filled with mercury upside down in a bowl of mercury, Pascal questioned what force kept some mercury in the tube and what filled the space above the mercury in the tube. At the time, most scientists including [[Descartes]] believed in a plenum, i. e. some invisible matter filled all of space, rather than a [[vacuum]] ("[[Nature abhors a vacuum]])." This was based on the Aristotelian notion that everything in motion was a substance, moved by another substance.<ref>Aristotle, ''Physics'', VII, 1.</ref> Furthermore, light passed through the glass tube, suggesting a substance such as [[Luminiferous aether|aether]] rather than vacuum filled the space.

Following more experimentation in this vein, in 1647 Pascal produced ''Experiences nouvelles touchant le vide'' ("New experiments with the vacuum"), which detailed basic rules describing to what degree various liquids could be supported by [[air pressure]]. It also provided reasons why it was indeed a vacuum above the column of liquid in a barometer tube. This work was followed by ''Récit de la grande expérience de l'équilibre des liqueurs'' ("Account of the great experiment on equilibrium in liquids") published in 1648.