Physicists are often told that the invention of the steam engine, and later, information theory, are the only documented instances of a technology preceding the science upon which it is based. To this meagre list I would suggest the addition of many ancient and modern terrorist technologies. The uncaring pragmatism of mediaeval alchemists, engineers and warriors ensured that from the 4th century weapons of extreme viciousness and destructive power were in regular use.
With pools of oil lying naturally on the surface of Middle Eastern countries such as Iran and Iraq1, one did not have to be a ‘rocket scientist’ to discover that rags soaked in such material would burn fiercely, and effectively become firebombs. Hurling fire in the face of an enemy saved Constantinople from conquest for 700 years. The distillation of light oil by Mary, the female Egyptian chemist, later opened up new technical possibilities, and for a time incendiary devices were all the rage. Indeed the availability of a ‘liber ignium’ or book of fires, made recipes for sophisticated incendiary devices widely available by the 12th century.
For example, a mixture of sulphur, bitumen, pyrites, mulberry juice and quicklime, mixed and stored in an airtight tin was particularly effective. It appears that this mixture if rubbed on the shoulders of an enemy by night would spontaneously ignite once the sun was up. Just how one would carry out this difficult anointment is not clear, but apparently it often worked to the satisfaction of the terrorists concerned.
The advent of explosives of course altered the landscape considerably. The old weapons, like Greek fire [burning oil fired from a stinup-pump] and the handheld firebomb [known as a Molotov cocktail centuries later] became passé. Black powder, a mixture of salt petre (potassium nitrate), sulphur and charcoal, was first used in China in the 10th century, and in the following three centuries explosive projectiles were developed, often fired from bamboo tubes. It is interesting to note that it was not until the 17th century that explosives were used for a peaceful purpose, specifically mining.
Once explosives were available, then the drive was on for greater shatter or blast power. World War I saw the arrival of TNT (trinitrotoluene), followed by RDX (cyclotrimethylene trinitrate) in World War II. The evolution of plastic explosives then enabled the modern terrorist to generate materials of varying stability by adding plasticisers to RDX, and generate such indiscriminate weapons as car bombs and self-immolation devices.
So what can the physicist or reader of this journal do to address the dangerous contemporary situation in which the terrorist seems to hold all the cards and have everything from surprise to devastation in his or her hands? Vigilance is clearly useful but not the solution to the problem of identifying modern explosives where they are planted. Fortunately, CT scanners for medical and other purposes can now be adapted to anti-terrorism functions, at great financial cost. In addition, atomic and nuclear scattering methods have proven useful in identifying nitrogen rich explosives, such as Semtex, in luggage and containers. Such analytical methods are expensive and still in the developmental stage.
There is still work to be done, and a need for scientists to seek effective solutions to the explosive identification problem. A conference on the Application of Nuclear Techniques, held in Mykonos (Greece) in 1991 attempted to address this matter. While many half-solutions were offered, this participating physicist was left with the firm impression that it was still virtually impossible, using existing techniques, to distinguish between Semtex in a terrorist’s luggage and nitrogen-rich oilseeds in the pocket of a Saskatchewan farmer. Much technical research still needs to be done; most of it unrewarding for the basic scientist.
Jasper McKee, P.Phys.
Editor, Physics in Canada
mckee@physics.umanitoba.ca