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[资源] Electricity and Magnetism Textbook--by Benjamin Crowell

Preface

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 though 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.

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[ Last edited by zhq025 on 2008-1-16 at 10:44 ]

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