In an atomic explosion, an initial neutron collides with a nucleus in the charge. It fissions, releasing more neutrons, which fission more nuclei, and the resulting fast chain reaction runs away. But a practical bomb cannot wait for a random neutron to set it off. It fires a quick blast of neutrons into the charge at the moment of initiation. Enormously amplified by successive generations of fission, they get the chain-reaction off to a flying start.

Daedalus is now adapting the idea to the explosions in an internal-combustion engine. They too are chain reactions, the links in the chain being the free radicals liberated by combustion. Sadly, these chains are usually terminated prematurely. Unburnt and partly burnt fuel emerge in the exhaust, polluting the atmosphere.

So Daedalus's new ‘radical engine’ has a powerful xenon ultraviolet flash-lamp directed into each cylinder. A brief instant after the charge is ignited, the flash-lamp fires, suddenly photolysing the mixture and flooding it with radicals ripe for chain-amplification. Combustion roars away. With radical creation outpacing quenching, it goes to completion at last. Only carbon dioxide and steam emerge from the exhaust.

The radical engine will need careful optimizing. Fired too soon, a flash may detonate the whole charge very suddenly, causing engine ‘knock’. Fired too late, it may shine uselessly on a few dying radical chains. Possibly several spaced flashes of different intensity will do the best job. But when properly understood, radiant radical-amplification will give internal combustion a splendid new lease of life. Not only will a radical engine be cleaner, and able to burn all sorts of fuels now too smoky or sluggish for the job. By varying the timing and intensity of its flashes under electronic control, it will be more efficient, too. It will be able to burn the charge faster or slower, optimizing the pressure-profile of each power-stroke for the current speed and load.

The technique might also work with solid high explosives. In mines, tunnels and similar confined spaces, truly clean and fumeless blasting would be very welcome. And fast-acting flash electronics might produce what is now only a figure of speech — a true controlled explosion. With its pressure adjustable in space and time, it could be a splendid tool for forming and shaping hard, intractable alloys and ceramics. Indeed, it could even lead to new and neater designs of atomic bomb.