In existographies, Parmenides (510-450BC) (IQ:180|#127) [RGM:216|1,500+] (GPhE:7) (ACR:11) [CR:118] was Greek physicist-philosopher noted for his circa 485 BC treatise “On Nature” in which he argued that a void or rather a vacuum, in nature, could not exist. [1]

This famous postulate, and the two-millennia long debated on this issue that followed, can be said to be directly responsible for the invention or development of a number of things: barometer (1643), vacuum pump (1650), piston and cylinder (1650), air pump (1657), steam engine (1690), gas laws (1645-1897), and the science of thermodynamics (1865).

Vacuum debate

See main: Nature abhors a vacuum

Parmenides' famous "denial of the void" erupted into what would become a 2,000-year heated and intricate debate, with views going back and forth on the matter, as to whether or not voids or vacuums can or cannot or do or do not exist. The first to object to Parmenides' denial was Leucippus who invented the now-famous atomic theory, which was stimulated into conception to purposely contradict Parmenides; the short version of Leucippus' theory being that the postulate that everything in the universe is either atoms or voids.

Next, Plato found the the idea of a vacuum inconceivable. After Plato, Aristotle, student of Plato, declaring the famous dictum horror vacui or “nature abhors a vacuum”, on the logic that in a complete vacuum (see also: perfect vacuum) infinite speed would be possible because motion would encounter no resistance, hence if infinite speed was impossible, so to is a vacuum.

In circa 1648, German engineer Otto Guericke began to devote a considerable portion of his spare time to experimentation and was especially fascinated with the nature of cold, much of which was centered on the question of the void: [2]

“Could empty space exist, and is heavenly space unbounded?”


A Schott diagram depiction of German engineer Otto Guericke's famous circa 1649 beer keg vacuum experiment, in which Guericke and another man (or Guericke's two assistants) try to completely evacuate the air form a well-caulked beer keg, so to see if a "vacuum" could be made, the existence of which that was deemed impossible by Parmenides.

A Schott diagram depiction of German engineer Otto Guericke's famous circa 1649 beer keg vacuum experiment, in which Guericke and another man (or Guericke's two assistants) try to completely evacuate the air form a well-caulked beer keg, so to see if a "vacuum" could be made, the existence of which that was deemed impossible by Parmenides.

In researching this query, he was brought into contact with German mathematical physicist Gaspar Schott, an adherent to Aristotle’s version of the denial of the void, albeit open to new experimental information, and ultimately and to French scientist philosopher Rene Descartes’ adherence to the “denial of the vacuum” dictum. This puzzle intrigued Guericke and he went to work trying to evacuate the air form a well-caulked beer keg (adjacent), which introduced him to the sealing problem, i.e. how to make a container air tight. After solving the sealing problem, Guericke was said to have discovered the phenomenon of the compressibility of air after which he invented a vacuum pump.

Schott recorded, diagrammed, and documented all of the Guericke's experimental results, which he appended to his own massive book The Mechanics of Gas Hydraulics.

In 1854, Guericke built the Magdeburg hemispheres to publicly prove that vacuums can exist in nature. Investigations of this same question, by others, led to the development of the thermometer, the steam engine, and eventually the science of thermodynamics, among others.

Quotes | On
The following are quoted by Popper:

“Parmenides’ theory may be described as the first hypothetico-deductive theory of the world. The atomists took it as such; and they asserted that it was refined by experience, since motion does exist. Accepting the formal validity of Parmenides’ argument, they inferred from the falsity of his conclusion the falsity of his premise. But this meant that the nothing — the void, or empty space — existed. Consequently, there was now no need to assume that ‘what is’ — the full, that which fills some space — had no parts; for its parts could now be separated by the void.”
— Karl Popper (1958), “Back to the Presocratics” [4]

Quotes | By
The following are representative quotes:

“Being is unbegotten, indestructible, whole, eternally one, immovable and infinite. With it there is no was nor shall be; the whole is forever now, one and continuous.”
— Parmenides (c.460BC), Publication; cited by: Henry Bray (1910) [3]

See also
● Heraclitus vs Parmenides

References
1. Thims, Libb. (2007). Human Chemistry (Volume One) (section: Vacuums in nature, pgs. 46-47). Morrisville, NC: LuLu.
2. Partners and Rivals during the Scientific Revolution – Faculty.Fairfield.edu.
3. Bray, Henry T. (1910). The Living Universe (pg. 251). Truro Publishing Co., 1920.
4. Popper, Karl. (1998). The World of Parmenides (foreword: Scott Austin; editors: Arne Petersen, Jorgen Mejer) (§1: “Back to the Presocratics”, pgs. 7-35; quote, pg. 19; §2: The Unknown Xenophanes, pgs. 36-75). Routledge, 2012.

Further reading
● Parmenides. (470BC). Fragments; in: Early Greek Philosophers (editor: John Burnet) (§4). Publisher, 1982.
● Miller, Mitchell H. (1986). Plato’s Parmenides: the Conservation of the Soul. Princeton University Press, 2017.
● Cohen, S. Marc, Curd, Particia, and Reeve, C.D.D. (2011). Readings in Ancient Greek Philosophy: From Thales to Aristotle (§6:Parmenides of Elea, pgs. 40-46). Hackett Publishing.

External links
● Parmenides – Wikipedia.
● Parmenides – Stanford Encyclopedia of Philosophy.