Introduction
Following the great intellectual silence of the Dark Ages, the issue of the vacuum and the Void resurfaced once the ancient Greek writings, so carefully kept by Arabic scientists, re-emerged in the western world between the 11 and 13th centuries. The character of the philosophical discourses had barely changed from their ancient predecessors. The arguments raised by Medieval philosophers can only be classified as tedious by our present style of logical thinking.
The dark nebula in IC 2944 might serve as a visual analogue to an empty space or The Void, although it is actually a region of interstellar space filled with light-absorbing gas and dust. (Source: Hubble Space Telescope.)
Can a Vacuum Exist in Nature?
Beginning from a cornucopia of peculiar assumptions, the various factions squared-off on one side or another of the issue of whether a vacuum, or Void could exist in nature. We know from the treatises written on this matter since the 12th century what the lines of thinking were. The reason that a vacuum presented so much conceptual and philosophical difficulty involved various flavors of the following argument:
Void is a free place in which there is nothing; but Place is a property of bodies, which cannot reside except within a body; so a Void would have to contain "a body which is not a body" hence the logical contradiction.
For centuries the concept of "place" was logically anchored to the presence of a physical body which was an object of substance and could not occur within a Void.
Void as Logically Impossible - God's Dilemma
By the 13th century, philosophical discussions about The Void led some to the conclusion that if the existence of the Void were logically impossible, not even God with his infinite powers could create such a condition. This limitation on God's divine power led to the Condemnation of 1277 by Bishop Etienne Tempier of Paris, who struck down dozens of lines of philosophical discourse as contrary to Church doctrine, and an excommunicable offense. It was not the business of Mortals to limit what God could or could not do. Philosophers soon discovered, however, that there was little that the Church was actually prepared to do to punish transgressors of this new doctrine, and the discussions about the Void resumed.
Philosophers like Henry of Ghent soon found a logical way out of God's dilemma. A Void can exist 'accidentally'.
Henry argued that,
"The Void had no other existence than an accidental existence, in that the bodies between which it exists are disposed in such a manner that the dimension of a body is capable of being placed between them."
Accidental Void
God could create a Void, for example, by moving Heaven and Earth, but the Void created by the displacement would be an accidental one. God had intended to move the universe, but had not intended to create a Void, therefore the Void was accidental. Accidents are not covered by natural laws or logical consistency, and therefore God is not bound by them according to John Buridan. As late as 1690, John Locke was wondering whether if God placed a man it the Void, if he could even stretch out his hand beyond his own body. While philosphers mused over the existence of Void and vacuum, some progress had also been made in filling-in details of this universe not originally provided by Aristotle.
Nested Spheres
By the Middle Ages the celestial spheres were universally accepted as real, material phenomena. The spheres were transparent except for the denser portions which represented the planets and stars. The spheres were nested one within the other in perfect contact to avoid forming Aristotle's abhorrant vacuum. They also moved without friction and produced no heat. Campanus of Novara during the 13th century was even able to determine the size of the medieval universe, estimating from geometric considerations that the visible universe was no larger than 73 million miles, and that the sun was 4 million miles from the earth. Saint Thomas Aquinas identified no fewer than 3 Heavens in the celestial region.
The traditional 7 spheres of the planets, and the sphere of the fixed stars were the Sidereal Heaven; next beyond them was the Crystalline or Aqueous Heaven created on the first day of Genesis as "...the waters above the firmament...;" then came the Empyrean Heaven which was full of light and the abode of the angels. There were also four additional 'sublunary' Heavens; Fiery, Olympian, Etheral and Airy, making a total of Seven Heavens distributed over 13 spheres. Discussions of the Void not withstanding, for the practical Natural Philosopher wishing to get on with the business of predicting the positions of the planets in the sky, the most widely accepted model for the solar system by the 15th century, was still that of the Alexandrian astronomer Cladius Ptolemy.
In Ptolemy's well-known, earth-centered solar system, the planets rode on crystalline spheres centered on the earth. Even Nicolas Copernicus who sparked the heliocentric revolution in 1534 with his near-posthumus publication of "De Revolutionibus Orbum Celestum" preferred the prevailing view that the crystalline spheres existed, only with Copernicus, their centers were at the Sun.
But this idea of nested, crystalline spheres holding-up the universe, finally had to be abandoned when Tycho Brahe observed two astronomical events: the Nova of 1572 and the Comet of 1577.
Tycho observed both of these phenomena from different locations, but was unable to detect through his angular measurements any sign of a parallactic shift. Tycho's failure to detect parallax in the new 'guest star' of 1572 as well as the comet, compelled him to state that both objects must be outside the Earth's atmosphere and beyond the orbit of the Moon. This observation at once placed these events in the Siderial Sphere where it had been unquestioned for centuries that no change could ever occur. All celestial bodies were made from Aether which was supposed to be a perfect, uncorruptable and unchangeable substance. The comet and the nova immediately disproved this central tenant of celestial structure and composition. Moreover, the daily motion of the comet also convinced Tycho that its path must actually intersect the orbits of the other planets, thus destroying the crystalline spheres on which they were attached.
Nested Spheres Fade Closer to Observed Reality
According to a broadside written by Tycho
"...Now it is quite clear to me that there are no solid spheres in the heavens and those that have been devised by the authors to save the appearances exist only in the imagination for the purpose of permitting the mind to conceive the motion which the heavenly bodies trace in their course..."
A colorized version of the Flammarion woodcut, of a man exploring the meeting of Earth and sky revealing the heavens beyond. (Original by Camille Flammarion, Source Wikipedia.)
The 'authors' of course refered to over 2000 years of philosophers and astronomers no less impressive than the likes of Aristotle, Ptolemy and even Copernicus. If the planets were not attached to crystalline spheres what, in fact, did hold them up and cause them to move as they did?
Johannes Kepler was one of the first post-Copernican scientists to think about this problem and came up with a daring solution. A substance he called anima motrix emanated from the sun like rays of light, pushing the planets along in their orbits. At the same time that Kepler was thinking about this idea, William Gilbert, a personal physician to Queen Elizabeth, completed his studies of the properties of magnetism and discovered that the Earth itself was a magnet. Gilbert was among the first to speculate that the Earth and Moon influenced one another through their magnetic properties. Kepler later incorporated Gilbert's work into his own solar system model by identifying the anima motrix with magnetism.
Preview Image
The Flammarion woodcut is an enigmatic woodcut by an unknown artist. It is referred to as the "Flammarion woodcut" because its first documented appearance is in page 163 of Camille Flammarion's L'atmosphère: météorologie populaire ("The Atmosphere: Popular Meteorology," Paris, 1888). The woodcut depicts a man, dressed as a medieval pilgrim and carrying a pilgrim's staff, peering through the sky as if it were a curtain to look at the inner workings of the universe. One of the elements of the cosmic machinery bears a strong resemblance to traditional pictorial representations of the "wheel in the middle of a wheel" described in the visions of the prophet Ezekiel (see Merkabah). The caption in Flammarion's book translates as "A missionary of the Middle Ages tells that he had found the point where the sky and the Earth touched..." The image accompanies a text which reads, in part, "What, then, is this blue sky, which certainly does exist, and which veils from us the stars during the day?" The woodcut is often described as being medieval due to its visual style, its fanciful vision of the world, and to what appears to be a depiction of a flat Earth.
(Source: Color Image - Game of Order Wiki, "Ether." Text - Wikipedia, "Portal:History of science/Previous pictures.")
Citation
Odenwald, Sten, Ph.D. (Contributing Author); Bernard Haisch (Topic Editor). 2009. "Space: The Void." In: Encyclopedia of the Cosmos. Eds. Bernard Haisch and Joakim F. Lindblom (Redwood City, CA: Digital Universe Foundation). [First published January 5, 2008].
<http://www.cosmosportal.org/articles/view/137765/>
Contact Us
Send to a Friend
Comments
There are no comments.