The study suggests that when a computer crashes or smartphone freezes it may be down to the impact of electrically charged particles generated by cosmic rays that originate outside the solar system. Professor Bharat Bhuva said: “This is a really big problem, but it is mostly invisible to the public.” When cosmic rays traveling at fractions of the speed of light strike the Earth’s atmosphere they create cascades of secondary particles including energetic neutrons, muons, pions and alpha particles. Prof Bhuva said that millions of the particles strike your body each second. Despite their numbers, this subatomic torrent is imperceptible and has no known harmful effects on living organisms. But a fraction of these particles carry enough energy to interfere with the operation of microelectronic circuitry. When they interact with integrated circuits, they may alter individual bits of data stored in memory. This is called a single-event upset or SEU. Since it is difficult to know when and where these particles will strike and they do not do any physical damage, Prof Bhuva said the malfunctions they cause are very difficult to characterise. As a result, determining the prevalence of SEUs is not easy or straightforward. Prof Bhuva said: “When you have a single bit flip, it could have any number of causes. “It could be a software bug or a hardware flaw, for example. The only way you can determine that it is a single-event upset is by eliminating all the other possible causes.” He said there have been a number of incidents that illustrate how serious the problem can be. For example, in 2003 in the Belgian town of Schaerbeek a bit flip in an electronic voting machine added 4,096 extra votes to one candidate. Prof Bhuva said the error was only detected because it gave the candidate more votes than were possible and it was traced to a single bit flip in the machine’s register. In 2008, the avionics system of a Qantas passenger jet flying from Singapore to Perth appeared to suffer from a single-event upset that caused the autopilot to disengage. As a result, the aircraft dived 690 feet in only 23 seconds, injuring about a third of the passengers seriously enough to cause the aircraft to divert to the nearest airstrip. Prof Bhuva said there have been a number of unexplained glitches in airline computers - some of which experts feel must have been caused by SEUs - that have resulted in cancellation of hundreds of flights resulting in significant economic losses. Prof Bhuva said: “The semiconductor manufacturers are very concerned about this problem because it is getting more serious as the size of the transistors in computer chips shrink and the power and capacity of our digital systems increase. “In addition, microelectronic circuits are everywhere and our society is becoming increasingly dependent on them.” He added: “It is only the consumer electronics sector that has been lagging behind in addressing this problem. “This is a major problem for industry and engineers, but it isn’t something that members of the general public need to worry much about.”
