KentuckyFC writes: Transcranial magnetic stimulation involves placing a human in a rapidly changing magnetic field that is powerful enough to induce eddy currents in the brain. Focus the field in the visual cortex, for example, and the induced eddys cause the subject to 'see' lights that appear as discs and lines. Move the the field within the cortex and the subject sees the lights move too. But if this happens in the lab, then why not in the real world too, say physicists who have calculated that the fields associated with certain kinds of multiple lightning strikes are powerful enough to induce the same kind of visual hallucinations in anybody unlucky enough to be within 200 metres or so. These fields ought to induce hallucinations similar to those experienced in the lab. These would take the form of luminous lines and balls that float in front of the subject's eyes, an effect that would explain observations otherwise classed as ball lightning, say the scientists.