Jake's Science Site

An Introduction to Physics

A common definition of physics is the study of matter and its motion through space and time. This does encompass what physicist currently study, but I think it misses what is philosophically at the heart of physics as a science. For this reason I prefer to define physics as the study of the first principles of science.

A first principle is a statement about nature that can't be derived from nor assumed to come from another established principle. This does not mean that we will not discover other first principles that supersede the ones we currently know, it just means this is where the field of physics currently stands. For example, Newton's laws are historically called first principles but have been superseded by general relativity and quantum field theory. Physicists currently do not study Newton's laws, but since they can be derived from currently-accepted first principles, they provide a gateway to connect physics to other fields.

In studying first principles, physicists do not only try to refine them, they also try to connect them to other concepts in science. For example biologists discover how life forms behave and how they interact at macroscopic and microscopic levels. But it is the goal of the biophysicist to discover how atoms and molecules interact, form structures, and move which yield the properties of life that biologists have found. Since the structure and motion of atoms directly connect to the first principles of science, once their connection to biology has been made, the biophysicist has connected that concept in biology to physics. In reverse when biologists, geologists, and other scientists make a new discovery, they do not say it violates the first principles of science, which would divide science. Instead they assume it is connected to the first principles, but that they do not know how, and establishing how is part of physics.

The goal of the rest of this section is to provide short introductions to concepts in physics. Think of these introductions as an alternative, and supplemental, to what is provided in typical courses. All of the introductions are in their first versions, so there may be errors!

Electricity and Magnetism

  1. Electric Forces and Potentials (PDF|DOCX)
  2. Current and Resistance (coming soon)