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Littered across the Internet are
dozens of home videos of people putting a lit match into
their microwave oven, turning it on and waiting for the inevitable chaos to ensue:
a spitting, sputtering ball of brilliant white fire that seems to hang
magically in the air until it floats upward and scorches the hell out of the
microwave ceiling.
Some of the mischievous miscreants responsible for turning their kitchens
into science experiments claim to have recreated a mysterious natural
phenomenon known as “ball
lightning,” which resembles
the fiery spheres created in the microwave and is thought to be the byproduct
of lightning strikes. But are these glowing orbs created in an appliance
normally reserved for reheating leftovers really the same thing as ball
lightning?
Several
scientists in the relatively small field of “ball-lightning-ology” say that it isn’t quite the same
thing. “It’s not the same as the ball lightning that we are talking about,”
says Antonio Pavão, a professor of chemistry at the Federal University of
Pernambuco in Brazil who has successfully created a ball lightning-like
phenomenon in his lab.
Reports often describe naturally-occurring
ball lightning as a luminescent white-blue or white-orange ball, which are, on
average, about the size of a grapefruit. It can move through the air on its own
for seconds and even minutes, bouncing off most things it touches until it
either fades away or explodes. Sightings are reported most often during
thunderstorms when lightning
actively strikes the ground. Not to be taken lightly, ball lightning has
reportedly even killed people.
But until recently scientists did
not take the phenomenon very seriously, and some did not even think it existed
at all. Several theories were floated around to explain the mechanism of ball
lightning, but only one has gained ground in recent years. It was proposed by John Abrahamson and James Diniss, professors of
chemical engineering at the University of
Canterbury in Christchurch, New
Zealand.
The inspiration for their theory
were the glass-like globules of silicon, called fulgurites, found in the ground
after lightning hits silicate-rich soil (silicates are compounds containing
silicon and oxygen.) They proposed that, in addition to the formation of fulgurites, inconceivably small particles
of pure silicon, smaller than 100 nanometers, were being vaporized and ejected
out into the air during a lightning strike.
Once in the air, these silicon
particles would begin to condense together and react with oxygen in the
atmosphere, giving off heat and light and creating a fiery sphere of ball
lightning.
A nice theory, but only in the
last several years have scientists been able to verify it by creating something
similar to ball lightning in the lab. For example, a group at Tel-Aviv University in Israel created a ball lightning-like effect
by shooting microwaves
at blocks of silicate. However, the effect only lasted for a scant 30
milliseconds once the microwaves were turned off.
More recently, Pavão’s research group in Brazil created a ball lightning-like effect
that lasted anywhere from eight to ten seconds, which more closely mimics the
behavior of the real thing. Pavão sent an electric current into a wafer of pure
silicon, conditions strikingly similar to those of real
lightning hitting the ground.
According to both Pavão and
Abrahamson, the spectacle that you can create in your microwave oven is more like the Tel-Aviv University group’s experiment than actual ball
lightning. Outside energy from the microwave is sustaining the fireball instead
of internal chemical energy caused by reaction with the atmosphere. “The
important difference is the lifetime of the balls,” says Pavão. “The natural
phenomenon is different because there is no need for an additional source of
energy and the lifetime is minutes.”
This answer is provided by Scienceline,
a project of New York
University's Science,
Health and Environmental Reporting Program.
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