Is it really ball lightning? I have to be very skeptical about the premise that magnetic fields are generating phosphenes that appear to be ball lightning (“Great balls of magnetism!” p. 68, July 2010). My experience with phosphenes, which agrees with that of others I’ve asked, is that the effect is extremely fleeting – lasting a second or two at most. On the other hand, anecdotal accounts of ball lightning sightings would seem to agree that the effect lasted for more extended periods while the observer “tracked” the progress of the ball. While I have no better explanation, the phosphene phenomenon seems too ephemeral to explain the visual effect. When the answer is found, it is my opinion that it will be a plasma phenomenon. Perhaps, under the right conditions, a plasma generates a magnetic field sufficient to contain the plasma for a brief time. Peter Rahm Randolph, Vt. “Might” and “could” and lightning Please allow me to comment on your article about the Innsbruck University research of Alexander Kendl et al. on ball lightning (“Great balls of magnetism!” p. 68, July 2010). You certainly know the story of the astrophysicist, the physicist, the mathematician and the engineer who met at the occasion of a congress in Ireland. Suddenly, the astrophysicist pointed out the window to the horizon, exclaiming, “Look at that! In Ireland, the sheep are black!” The physicist replied: “Don’t generalize, dear colleague; the only thing you can infer is that in Ireland, there are black sheep!” Immediately, the mathematician corrected, “The only thing, dear colleagues, that you can state with assurance is that in Ireland, there is at least one sheep that is black.” On this, the engineer dryly remarked, “Dear colleagues, don’t forget that the only thing you really saw and know at this point is that one side of one sheep in Ireland is black.” The Innsbruck researchers are thus rather in the role of astrophysicists, who, based on scarce experimental data, and with the help of probability and many “mights” and “coulds,” knit together the most wonderful theories. Honor to the experimental data and to all people who write down and report their observations about scarce and unexplained natural phenomena without fearing that others might laugh about them. Such observations and such people are at the roots of mankind’s progress. On the other hand, theories based on “mights” and “coulds” do not really bring us forth. Dr. Edgar Müller Prilly, Switzerland