What is Physics?/Introduction - Notes

1. What is Physics?
1. Physics is the study of matter, energy, and their interactions.
2. Physics is the science that seeks to explain how the universe works. Physicists create theories to explain their observations of nature. These theories must make testable predictions. If the predictions prove false, the theory is modified or discarded. In this manner, physics evolves toward truth.
2. Aristotle (384 B.C. - 322 B.C.)
1. Aristotle was a Greek philosopher whose assumnptions derived from his observations of nature became the cornerstone of scientific thought for the next two millennia. However many of his assumptions have proven false through experimentation and scientific scrutiny.
2. Aristotle believed that all matter in the universe was composed of four elements.
1. Earth
2. Water
3. Air
4. Fire
3. Aristotle believed that all matter had a natural place. Earth was at the center of the uiniverse, water was outside the realm of earth, air was outside the realm of water and fire was outside the realm of air.
4. When an object was set into motion eventually that motion would be dictated by its natural place. Everyday occurences appeared to bear this out. Rock dropped from a hand fell to the earth, air bubbles in water rose to the surface, and flames of a fire shoot upwards.
5. This model also explained why heavier objects fell at a faster rate than lighter objects. Heavier objects contain more earth and therefore have a greater "eagerness" to return to their natural place than lighter objects
6. Once in their natural place matter has no reason to be in motion therefore it comes to rest. Rest is considered by Aristotle to be the natural state for all matter. Again, everyday occurences appear to bear out Aristotle's model
3. Galileo (1564 - 1642)
1. Galileo was an Italian who is regarded as the "Father of Modern Science" for popularizing the use of experimentation to test the assumptions (hypotheses)developed through systematic observation.
2. These experiments of Galileo showed the weaknesses in Aristotle's assumptions and eventually would lead to end of Aristotelian thought.
3. Among other things Galileo determined that the sun was the center of the universe, all objects fall at the same rate regardless of size, and rest or constant motion could be the natural state for any object.
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