THE SECRET OF BALL LIGHTNING
For centuries, people have told stories about luminous balls that suddenly appear in the air during storms. Now, scientists have revealed that magnetic mess in the atmosphere could be the cause of the enigmatic phenomenon.
Reports of ball lightning have been around for hundreds of years. But evidence was always scant. Now we think we know how it works...
Thick, grey clouds from the English Channel slowly drift across the small seaside town of Paignton in South-Western England. In mid-afternoon, the first heavy drops fall, while 71-year-old Michael Dodd is in his living room, watching TV. Suddenly, he hears a deafening bang, and the power fails. A few seconds later, a glowing, bluish ball the size of a beach ball with an orange tail of light sails through his window, drifting across the room close to Michael Dood, who is in shock, and out his terrace door. Once outside, it crosses the parking space in front of the small cluster of houses for senior citizens and disappears out of sight.
The event, that took place in September 2017, is an example of ball lightning – an enigmatic, glowing ball with a typical diameter of up to one metre, which suddenly appears during a thunderstorm, drifting quietly across open spaces or through occasional living rooms, only to suddenly disappear. Scientists have struggled to understand how the ball-shaped lighting forms, and now a team of Finnish and American physicists have been the first to recreate the process, which probably causes the odd phenomenon.
History is ripe with shining balls
The earliest accounts of phenomena that might have been ball lightning are more than 2,000 years old and exist in Estruscan works of art and the writings of Greek philosopher Aristotle. One of the earliest reliable accounts is from 1638, when, according to several sources, the church of Widecombe-in-theMoor in Southern England was struck by ball lightning in the middle of service. The ball shattered parts of the roof and pushed the church benches over, setting them on fire. Four people were killed.
Similarly dramatic examples also exist in modern times, such as ball lightning inside planes. This happened on 15 December 2014 to flight BE-6780 from Aberdeen to the Shetland Islands. The cabin crew saw a shining ball appear brieflty close to the cockpit door a few seconds before lightning struck the plane’s radar equipment, causing an electric system error. However, the pilot regained control of the aircraft, turned back, and landed safely in Aberdeen 35 minutes later.
In spite of the many accounts of ball lightning, there is not much persistent tangible evidence and scientific explanations of the odd phenomenon.
Optical illusion
So far, scientists have had most difficulties explaining the balls’ ability to remain stable for up to one minute, before they disintegrate. In traditional physics, the behaviour of ball lightning is so unlikely that an article in the Physics Letters from 2010 claimed that they do not exist. According to the authors, the balls had to be optical illusions produced on the retina by the forceful magnetic fields of thunderstorms.
Since the article was published, Chinese scientists have registered and analysed natural ball lightning using scientific equipment. The lightning occurred in the Tibetan Plateau in 2012 and had a diameter of five metres – much larger than the one metre mesaured by typical ball lightning. It also had a much shorter life of 1.6 seconds. The scientists’ analyses showed that the ball’s most important ingredient was silicon oxide and carbon from the ground, which ordinary lightning had partly converted into plasma by heating it to some 30,000 degrees.
The recordings proved that ball lightning exists, but they did not reveal the process that makes lightning shine and live as stable balls. That discovery has only just been made in an experiment carried out by the Finnish and American team of physicists.
Ball lightning was accidental
The aim of the scientists’ experiment was originally quite different, as they wanted to be the first to produce a special magnetic ball in the quantum world – the most basic level of physics research. Subsequently, the scientists learned that by producing the ball, they had accidentally proved a more than 20-year-old ball lightning theory.
The theory, which was introduced by Spanish professor Antonio F. Ranada in 1996, describes an internal structure of ball lightning, which explained all the unusual qualities, including how ball lightning can exist for such a long time. The structure that Ranada described mathematically was a type of electromagnetic knot of entangled, ringshaped, magnetic field lines that occur in a plasma of charged air molecules. The rings are stable, because they bite their own tails, so there is neither a beginning nor an end, and hence, they cannot be untangled.
The scientist and his team never got any further, as it was not possible to prove their theory, which was forgotten for more than 20 years – until the Finnish and US scientists’ experiment produced the magnetic field lines in the freezing contrast of red-hot plasma: the Bose-Einstein condensate.
The condensate is the fifth state of matter, which was only discovered in 1996. In the lab, scientists produced a very thin, microscopic cloud of 200,000 freezing cold rubidium atoms. The condensate was manipulated by means of a magnetic field, making the magnetic knots appear by themselves. The structure was maintained long enough for the scientists to be able to map out its characteristics, which are completely consistent with the about 20-year-
Knots generate unending energy
old prediction of the interior of ball lightning. Scientists have still not shown why ball lightning neither slowly burns out noremits heat radiation, when direct contact with lightning causes severe burns. However, the experiment is very important – not only for the understanding of ball lightning, but perhaps also for the development of fusion energy.
Fusion is when two light atomic nuclei fuse to generate energy such as in the interior of stars. It is a pure and almost inexhaustible source of energy – that is if scientists can make it work in reactors.
One of the problems that are still standing in the way of functional fusion reactors is the "trapping" of the 100-million-degree-hot plasma which the reactor must hold. No materials can tolerate such temperatures, but if scientists are correct to assume that knots hold the glowing plasma of ball lighning together, even larger knots might be created to keep a check on the reactor’s plasma. In this way, nature’s huge energy discharges might be the key to controlling the infinite energy source of the future.