Gizmo

EWAdams writes to point us to a New Scientist report that the mysterious phenomenon of ball lighting has now been created in a Brazilian research lab. The phenomenon has long been reported anecdotally but never explained or understood. Scientists have devised numerous possible explanations, including mini black holes left over from the Big Bang, but have had little success in producing working examples. From the article: "A more down-to-earth theory... is that ball lightning forms when lightning strikes soil, turning any silica in the soil into pure silicon vapor. As the vapor cools, the silicon condenses into a floating aerosol bound into a ball by charges that gather on its surface, and it glows with the heat of silicon recombining with oxygen. To test this idea, a [Brazilian] team... took wafers of silicon just 350 micrometers thick, placed them between two electrodes and zapped them with currents of up to 140 amps. Then... they moved the electrodes slightly apart, creating an electrical arc that vaporised the silicon. The arc spat out glowing fragments of silicon but also, sometimes, luminous orbs the size of ping-pong balls that persisted for up to 8 seconds." Here is a movie of the phenomenon.

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