The Enigma Of The Universe ► 1 ►What is the Universe? ► (B) Space And Time ► 1. In Western Philosophy ► Plato and Aristotle

Posted: 04.09.2014

After the Greek atomists, Plato has thought over the nature of space in his notable work Timeaus. Plato has used the term "Chora" for space. "Chora may be thought of as a substratum which remains when all the attributes of material bodies-weight, colour, etc-are abstracted from them. Moreover, the sensuous objects may be regarded as being actually constituted of Chora."[1] Thus Chora or space is invariably associated with matter and has no existence apart from it. Plato believed that God had created time together with the universe, and that space and time came into existence simultaneously.[2] He maintained that God had created time as a reflection of the real eternity.[3] He did not believe in the ultimate reality of space and time. In the confessions of St. Augustine (4th Century), the problem of time is discussed. He, like Plato, considered time as a subjective reality and asserted that except present the division of time into past and future was only imaginary.[4] He also maintained that time did not exist before the universe existed: "There is no time before he created the world."[5]

Aristotle's concept of space is slightly different from the concept of "chora". Being a realist, just as he assumes that material bodies are things that really exist, whether we happen to perceive them or not, so he assumes that the space and time in which they move are real features of the world that does not depend for its existence on our perceiving it. Aristotle conceives space as a sort of immovable vessel, into which you can pour different liquids. Just as the same pot may hold first wine and then water, so does the space giving substratum to different things. A jug or a pot may be called a place that can be carried about, while "space" or "place" may be called "an immovable vessel". Hence, defining the "place" of a thing, Aristotle says: "Place is the innermost motionless limit of the containing body."[6] It means that space (or place) is the common interface of the contained body and the container, or in other words place of a thing is the boundary or inner surface of the body which immediately surrounds the thing. The motion of contained and container can evidently be applied over and over again: this coin is contained in this purse, this purse is contained in this bag, this bag is contained in this room, the room is contained in this house, and so on. But when in the sequence of containers we arrive at the outermost of Aristotle's celestial spheres, we can go no further, since the outermost sphere is not surrounded by anything, it is not in any place."[7] It follows from this that there can be no empty space. In the last resort, "absolute space" is the actual surface of the outermost "heaven'' which contains everything else in itself but is not contained in any remoter body. Thus, all things, whatever they are, are "in" this "heaven". But it is not itself "in" anything else. In accordance with the standing Greek identification of determinate character with limitation, Aristotle holds that this outermost heaven must be at a limited distance from us. Actual space is thus finite in the sense that the volume of the universe could be expressed as a finite numbers of cubic miles or yards, though, since it must be "continuous", it is infinitely divisible. However, often you subdivide a length, an area, or a volume, you will always be dividing it into lesser lengths, etc, which can once more be divided.

You will never by division come to "points" i.e., mere positions without magnitude or divisibility.[8] Thus, in the philosophy of Aristotle, the total space of the universe was finite (though it was infinitely divisible). Space was due to the extension of bodies, it was connected with the bodies; there was no space where there were no bodies. The universe consisted of the earth and the sun and the stars: a finite number of bodies. Beyond the sphere of the stars there was no space; therefore, the space of the universe was finite.

Aristotle's famous definition of time is: "Time is the reckoning of motion as "previous" and "subsequent".[9] Aristotle has also considered time to be a measure of change with respect to before and after. Thus, his concept of time is based on change or motion, Whereas Plato believed time to be created by God, Aristotle considered it to be existing for ever.

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