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Classical Accounts of Space and Time

The Birth of Physics

The source of modern theoretical physics can be traced back to ancient Greece. While the Greeks were not the first to produce mathematical understandings of the physical reality we inhabit, they did introduce a novel way of assessing this reality.

Many of them, offered up ideas about the fundamental structure of matter, deriving material objects from earth, water, fire, air, or the infinite variety of atoms that could comprise them.

Democritus, conjectured that the sweet was composed of smooth rounded atoms, and the sour from angular atoms: this notion that the properties macroscopic objects should be explainable in terms of their imperceptible components, still underlies modern physics.

It was Aristotle who gave us the term physics, from his text Physike Akroasis, or Lectures on Nature.

In Greek, physis refers to a things nature, with Aristotle defining an objects nature as an internal source of motion, and rest that belongs to an object.

For him, an objects nature is revealed by its motion, the cessation of that motion, when left alone.

This description of the nature of a thing does not bring physics into contact with explaining the sweetness or sourness, but rather focuses on change and locomotion.

Physics is often defined as the study of Matter in Motion. This is part of the reason that physics relates to the other sciences in the way it does: all other sciences observe that which is made of matter, and in motion.

Aristotle believed that different materials express different motion, and in order to distinguish these, he needed to generalize the concept of motion.

He took the most intuitive path he could, noting that the natural motion of earth is downward, the same for water, albeit less so, and that fire rises.

However, this leaves the question of the meaning of downward: from this point Aristotle began theorizing, with his definition being "to move toward a particular place".

This particular place, for Aristotle, was the center of the universe, with him presenting the cosmos as a sphere, the outer surface of which contained the stars, in fixed positions.

This celestial sphere had a center point, to which all downward motion was directed, and upon reaching this point, objects would cease their motion.

Similarly, "up" is the direction of travel away from the center, which is the direction in which fire and air travel.

Thoughts: With all due respect for Aristotle, I have to disagree with this, due to the fact that while fire may rise "up", the up that it rises into is already inhabited by air- though I may be misunderstanding his conception of air in the fundamental, elemental sense.

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Classical Accounts of Space and Time