WILD FRIDAY
Magnetic Fields: Unavoidable Attraction
edited by
Ace in the Hole
Last
month's sun show was phenomenally spectacular.
Several National Science Foundation-funded observatories caught our local star in the act of
spitting out glowing filaments as large as 22 times the diameter of the Earth. It looked like dragon's breath streaming into space for 86,000 miles.
The wondrous aurora borealis, or northern
lights,are created by these flares which in this case reached as far south as Palm Springs, California. The flares
may also scramble ground communications, and create havoc with satellites by puffing up the atmosphere.
Oddly enough, these seemingly special effects are created by one of the most familiar (if least understood) forces in the universe. The same invisible influence that keeps a refrigerator magnet stuck to the
door. Good old magnetic fields are emerging as
major players in the universe at large--sculpting everything from the last gasps of dying stars to the dynamic centers of galaxies.
Magnetic
fields are among the most complicated phenomena they astrophysicists have to deal with and they shudder at this turn of events, "They're what every astrophysicist loves to ignore because they complicate things enormously," says UCLA's Mark
Morris.
No one understands completely how the sun slings out the
streams of electrically charged particles produced in the
flares--although it has something to do with how the tangled
magnetic fields inside the star get twisted as it spins, then snake to
the surface and snap.
Still, the sun's act is but a sideshow to what magnetic fields are
up to in the rest of the universe.
Astronomers announced last year that they had
discovered surprisingly strong magnetic fields hanging out in the
seemingly empty spaces between galaxies--a real puzzle. A
magnetic field is produced by moving electric charges, so how do
you create strong fields where you don't have many particles?
Recently discovered is the fact that magnetic fields are
responsible for molding multicolored clouds of glowing gas blown off like smoke rings from dying stars.
Astronomers reported last December that the strange
asymmetrical jets blown out of Supernova 1987A were most probably
caused by--that's right--magnetic fields, produced inside of the
collapsing star.
Because they combine some of the most complicated phenomena in physics magnetic fields in space are difficult to understand:
magnetism and fluid flow. The fields are created by flows of electrically charged particles that can swirl around unpredictably like
eddies in a stream.
In turn, the magnetic fields can steer the flow of particles,
directing them this way or that. This creates more fields, and so on
and so forth, the fields and flowing particles pulling each other up by
their sometimes beautiful bootstraps
.
It's not surprising that astrophysicists would just as soon not get
pulled into this vortex. "I deal with magnetic fields all the time, but
there's a lot of things I don't understand about them," said the
University of Rochester's Adam Frank, whose work helped solve
the mystery of the multicolored clouds.
This seemingly unavoidable phenomenon was proven
some years ago when Morris and colleagues found
strange magnetic filaments running hundreds of light-years right
through the center of our galaxy, in uncannily straight and narrow
rows. Dozens of these tightly bunched parallel fibers have been
found, all running perpendicular to the galaxy's nearly flat disk.
Very strong
magnetic fields seem to be the only reasonable explanation. If that is true, where did they come from? Morris thinks that possibly they
are primordial magnetic fields that became concentrated in the
center of our galaxy when it formed. But that only
pushes the question back in time. "Nobody has figured out how
magnetic fields first came into being in our universe," he said. "That's
the Holy Grail."
Morris' case-in-point- all the magnetic fields writhing inside stars and interstellar
clouds can probably be traced back to the early universe.
Even on small scales, of course, magnetism seems magical. A
refrigerator magnet sticks to the door because countless unseen
atoms inside line up in artfully arranged rows; each atom spins up its
own magnetic field with the help of its orbiting electrons.
Magnets manage to speak to each other across the chasm of
empty space. Opposites pull each other in as if by invisible hands.
Likes shove each other away with a palpable push.
"It's freaky," says Frank, "because you can feel the force, but
you can't see it."
Doctors use this mystical but useful phemonenon by reading the magnetic fields of atoms spinning inside our
bodies to create images of what ails us. The spinning iron core of
the Earth creates a magnetic field strong enough to shield us from
those streams of particles the sun spits out in our direction--a global
magnetic umbrella. Flipping magnetic fields even store the
information kept in computers.
Undeniably attractive, magnetism steers the compass of the universe. Wherever you go, it seems, this force will be with you.
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