Life's Potentials
81
object. The field is the region of space in which an electrical charge can
be detected, and it's measured in volts per unit of area.
Electric fields must be distinguished from magnetic fields. Like
charge, magnetism is a dimly understood intrinsic property of matter
that manifests itself in two polarities. Any flow of electrons sets up a
combined electric and magnetic field around the current, which in turn
affects other electrons nearby. Around a direct current the electromag-
netic field is stable, whereas an alternating current's field collapses and
reappears with its poles reversed every time the current changes direc-
tion. This reversal happens sixty times a second in our normal house
currents. Just as a current produces a magnetic field, a magnetic field,
when it moves in relation to a conductor, induces a current. Any varying
magnetic field, like that around household appliances, generates a cur-
rent in nearby conductors. The weak magnetic fields we'll be discussing
are measured in gauss, units named after a nineteenth-century German
pioneer in the study of magnetism, Karl Friedrich Gauss.
Both electric and magnetic fields are really just abstractions that sci-
entists have made up to try to understand electricity's and magnetism's
action at a distance, produced by no known intervening material or en-
ergy, a phenomenon that used to be considered impossible until it be-
came undeniable. A field is represented by lines of force, another
abstraction, to indicate its direction and shape. Both kinds of fields de-
cline with distance, but their influence is technically infinite: Every time
you use your toaster, the fields around it perturb charged particles in the
farthest galaxies ever so slightly.
In addition, there's a whole universe full of electromagnetic energy,
radiation that somehow seems to be both waves in an electromagnetic
field and particles at the same time. It exists in a spectrum of wave-
lengths that includes cosmic rays, gamma rays, X rays, ultraviolet radia-
tion, visible light, infrared radiation, microwaves, and radio waves.
Together, electromagnetic fields and energies interact in many complex
ways that have given rise to much of the natural world, not to mention
the whole technology of electronics.
You'll need a casual acquaintance with all these terms for the story
ahead, but don't worry if the concepts seem a bit murky. Physicists have
been trying for generations to solve the fundamental mysteries of elec-
tromagnetism, and no one, not even Einstein, has yet succeeded.