The most frequent question encountered in the long history of the study of ball lightning is not how the ball is formed or what its properties are, controversial as these problems may be. It is, rather, whether ball lightning really exists. Even following Arago's discussion of this question in 1838, to the present day a skeptical view has been repeatedly expressed. The obstacles to direct experimental study by well established scientific methods and the failure of theories to provide either a satisfying or a conclusive explanation account in large part for the persistent skepticism.

This attitude on the question of ball lightning is not a unique problem in the history of science. The fall of meteors to earth was long considered a superstition of ignorant peasants. Despite repeated observation of these fiery bodies the controversy at one point caused the removal and destruction of rare meteorite specimens from museum collections on grounds they were fraudulent objects of superstition. A thorough analysis of the question in 1794 by Chladni, a physicist whose major work was in acoustics, contained the conclusion that such objects do not originate on the earth and that they indeed fall from the sky. Chladni's study was based on observations by reliable witnesses and data on samples of meteorites, many of which were entirely unlike all the materials in the area where they were found. His result was, however, not widely accepted. The reality of the phenomenon was finally established by the appearance of thousands of stony meteorites in 1803 at L'Aigle, France. The reports of many reliable witnesses and a great number of actual specimens were cited in the authentication of the event by the physicist Biot for the French Academy of Sciences.

In the negative view of the existence of ball lightning the reported observations are ascribed to mistaken identification of other luminous natural objects and to optical illusions. Meteors are often held responsible for supposed appearances of ball lightning. Several reports originally identified in the literature as ball lightning appear to have been meteors. The flight of meteors, however, is almost invariably seen as a straight line, in contrast to the characteristic path of ball lightning which is often curved. Ball lightning furthermore appears during storms with very few exceptions, while meteors are observed only by a great coincidence at such times. AN ordinary lightning flash seen by an observer directly in its path may appear to be a ball. In the optical illusion which may result, the intense light from the flash persists as an optical image even when the observer changes his field of view. This it is suggested that the false image of the ball appears to follow a complex path.

Arago in the first comprehensive discussion of ball lightning took notice of this problem. In addition to the presentation of a number of evidently reliable observations he pointed out that an observer viewing the descent of the ball at an angle from the side is not subject to the optical illusion described. Arago's arguments were evidently effective with Faraday, who in rejecting theories that ball lightning is an electrical discharge took care to state that he did not deny the existence of these globes. The editor of the German edition of Arago's complete work, however had the temerity to insert a footnote with the categoric remark, "Ball lightning is the result of the action on the retina of the intense light of ordinary lightning" in Arago's chapter on this form of lightning.

Fifty years after the first publication of Arago's review of this problem the persistence of the image of ordinary lightning traveling directly towards the observer was again proposed, and Lord Kelvin at the meeting of the British Association for the Advancement of Science in 1888 commented that ball lightning is an optical illusion from a bright light. The uniform size reported in many cases of ball lightning was ascribed to an illusion associated with the blind spot of the eye.

A direct discussion between opponents in this long controversy took place during a meeting of the French Academy of Sciences in 1890. A large number of luminous globes resembling ball lightning appeared in a torrent which was the subject of a report to the Academy. The glowing spheres entered dwellings through chimneys, bored circular holes in windows, and generally displayed the highly unusual behavior ascribed to ball lightning. Following the presentation of this communication a member of the Academy commented that the extraordinary properties attributed to ball lightning should be considered with reservations since it seemed the observers were suffering from optical illusions. In the heated discussion which followed, the observations which had been made by uneducated peasants were declared of no value; whereupon the former Emperor of Brazil, a foreign member of the Academy attending the meeting, remarked that he too had seen the lightning.

from THE NATURE OF BALL LIGHTNING, (c)1971 Stanley Singer, Plenum Press, 1971