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===Physics in Antiquity===

===Physics in Antiquity===

The ancient [[Greeks]] thought of the material [[universe]] as being composed four different [[elements]]--[[earth]], [[air]], [[fire]], and [[water]].  Motion and interactions between objects were explained by the concept of "like desires like." For example, a rock fell back to the ground after being tossed in the air because it was composed mostly of earth; naturally, it desired to be near the earth's surface, which also consisted mostly of earth.  Furthermore, [[Aristotle]] held that the natural state of objects was to be at rest.  Hence, an object rolled along the ground stopped because its motion was contrary to its natural (motionless) state.  The planet Earth was considered to be the center of the universe, so all motion was measured relative to it.

Ancient [[Greek]] scholars, such as [[Democritus]] and [[Aristotle]], thought of the material [[universe]] as being composed four different [[elements]]--[[earth]], [[air]], [[fire]], and [[water]].  Motion and interactions between objects were explained by the concept of a "natural state" for each element.  Bodies tended to move towards their natural state, and remained motionless when they attained it.  For example, a rock fell to the ground after being tossed in the air because it was composed mostly of earth; as such, it moved toward its natural state at the center of the Earth as much as it was able.  The Greeks also made advances in [[astronomy]]; [[Ptolemy]] developed a geocentric (Earth-centered) model of the solar system.

The ideas of the Greeks formed a [[paradigm]] that lasted for over 1500 years, making it one of the most successful scientific theories ever in terms of length of time spent as the dominant viewpoint.

The ideas of the Greeks formed a [[paradigm]] that lasted for over 1500 years, making it one of the most successful scientific theories ever in terms of length of time spent as the dominant viewpoint.

===The Scientific Revolution===

===The Scientific Revolution===