1 of 1

Write now Article Tools

Page 3 of 4

the machine would deliver an answer.

And that would have been that, one imagines. Just another abstract proof of an abstract idea by an academic working in the dreaming spires and publishing interesting (to some) papers on the philosophy of mathematics. But then the Second World War happened.

Alan Turing's role in the decipherment of the German Enigma code is another story entirely and is not strictly relevant to matter in hand. Suffice to say that by 1942, the Enigma in all its variations (pun intended) was largely transparent to the code-breakers at Bletchley Park and the intelligence material it spawned (known as Ultra) was significant in aiding the Allies' eventual victory.

However, Enigma was not the only cypher used by the Germans. At the very highest levels, between Hilter and his generals, the Lorenz SZ40 cypher machine was used. Although similar in principle to the Enigma machine, the Lorenz cypher was vastly more complex, and it was not vulnerable to the techniques used to crack Enigma. Eventually a couple of the resident code-breakers managed to find a small weakness in the Lorenz cypher and a method of exploiting it. By this time, the Enigma cyphers were being cracked using a combination of human skill and the brute force searching of the mechanical "bombes" which has been designed for the specific task of decoding Enigma. Unfortunately, the bombes were not flexible enough to cope with the subtleties of the Lorenz cypher so it had to be decoded by hand. This took a long time; time which often rendered the intelligence gathered useless (if the message says "move the army tomorrow" and it takes two days to decode, there's no advantage to knowing the message).

Eventually, a method to mechanise the decoding was found. Max Newman was a mathematician at Bletchley Park but, more significantly, he was the one who had delivered the lecture on topology at Cambridge which had led Turing to the Entscheidungsproblem. Newman's design drew heavily on the idea of a Universal Turing Machine: it could be adapted to different problems; it could adapt itself to different problems. It was, without a doubt, what we would call today a programmable computer. It was named Colossus. And it nearly didn't get built.

The authorities at Bletchley Park had a look at Newman's design and discussed it and decided that it was technically impossible to build it. Fortunately, one member of the discussion group was an engineer called Tommy Flowers. He decided that he could build it. He

• << previous page
• 1
• 2
• 3
• 4
• next page >>

Add your voice

Know something about The legacy of Alan Turing?
We want to hear your view. Write now!