Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....


Who are you? However much you relate your identity to your physical appearance, you know that your personality ultimately resides in the unique arrangement of your brain's electrical network. Mary Shelley may have conceived of electricity as a mystical life force that could jerk the leg of a dead frog or animate Dr. Frankenstein's monster, but we now know the truth is both more subtle and more wonderful. Electricity is not the stuff of life but of consciousness.

Evidence is mounting that the universe has produced vast numbers of suitable habitats for life - including, within our own solar system, a watery ancient Mars and the oceans that lie under the icy surface of Jupiter's moon Europa. But even as we debate claims of fossilized Martian bacteria, a third generation of radio astronomers has found nothing but a wasteland of static in the search for extraterrestrial intelligence.

Is life ubiquitous in the universe but consciousness rare? In terms of geologic time, it took a mere wink of an eye for life to come into being on Earth once conditions were suitable, so there is every reason to believe that it exists elsewhere. Large-brained mammals, however, appear as a virtual afterthought in the record of our biosphere, which remains dominated by single-celled life. Now you begin your study of electricity and magnetism, the phenomena of which your own mind is made. Give some thought to this image of awesome loneliness: there may be no other planet in our galaxy of ten billion stars where a collection of electric charges and fields can ponder its own existence.

Last Update: 2009-06-21