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‘Ball lightning’ may be hallucinatory
By Alexandra Witze
Talk about a flash of insight.
Lightning strokes could
stimulate people’s brains
and cause them to hallucinate bright blobs of light
the same way a magnetic
medical procedure does,
two physicists propose in an
upcoming Physics Letters A.
That process could help
explain some reports of “ball
lightning,” mysterious floating orbs that have been reported for centuries but are poorly understood.
“We don’t claim to have a solution for
the mystery of ball lightning,” says study
coauthor Alexander Kendl, a plasma phys-
icist at the University of Innsbruck in Aus-
tria. “But this is a possible hypothesis.”
Lightning forms when electrical
charges become separated in a storm
cloud and build up electrical potential
between them, which is then discharged
in the sudden bolt. Lightning strokes
typically come in clusters. In some cases,
Kendl says, they can come very rapidly,
perhaps 20 to 60 strokes, each about 100
milliseconds long, raining down over the
course of several seconds.
These rare repetitive strokes, Kendl’s
team found, generate magnetic fields
similar in strength, and in how they rise
and decay over time, to those used in a
brain-stimulation technique called trans-cranial magnetic stimulation, or TMS.
TMS applies magnetic fields to the
brain to treat conditions such as depression. When the stimulation is applied to
the visual cortex, some patients report
seeing blobs of light. Such experiences
of seeing light when light is not actually entering the eye are known as phosphenes. (The pattern of light you see
when you rub your closed eyes is a type
Evanescent glowing orbs called “ball lightning” have
been reported for centuries, but never fully explained.
Others have proposed that ball lightning is hallucinatory, but this study is the
first to relate it to a known phenomenon.
Working with graduate student Josef
Peer, Kendl calculated that repetitive
lightning strokes would trigger phos-
phenes “astonishingly well.” A person
would need to be within about 200 meters
of the lightning to experience the effect.
Cheating the thermodynamic laws
Quantum effect could boost maximum efficiency of solar cells
By Laura Sanders
Atoms in a solar cell coaxed into a curious simultaneous quantum state may
convert sunlight into electrical energy
more efficiently than previously believed
possible, a new study proposes.
The laws of thermodynamics set the
upper limit of solar cell efficiency at
around 80 percent, says study author
Marlan Scully of Texas A&M University
in College Station and Princeton University. But this estimate doesn’t take some
quantum effects into account. Scully’s
model shows that the ultimate energy
efficiency can be pushed even higher.
Photovoltaic cells convert photons of
light into electrical energy. In a typical
cell, photons hit atoms and knock elec-
trons free, resulting in a roaming elec-
tron and an electron-hungry area called
a “hole.” Ideally, electrons are funneled
into a path, creating an electrical current.
But sometimes, they fall into a hole and
emit a photon, an energy-squandering
process called radiative recombination.