Tagged: Enigma machine

Pykrete revisted


pykrete meets hammer

pykrete meets hammer (Photo credit: Genista)

The current issue of New Scientist has a short but interesting piece about pykrete – the material, made of ice and saw dust, once proposed as the basis for aircraft carrier production during the Battle of the Atlantic – a conflict at its very peak 70 years ago.

In essence, while Britain, America and the Soviet Union between them could, by the end of 1942 deploy superior forces to the Nazis and deliver hammer blows – such as that seen at Stalingrad and in a smaller, but still strategically vital, way in the Western Desert, Britain was in severe danger of running out of food and fuel because of losses to the U-Boats in the Atlantic.

The battle was fought in science and engineering as much as in bullets, bombs and torpedoes. Radar (or RDF as the British called it) and Sonar (ASDIC was the British name) were not invented during the conflict but they were improved and perfected as a direct result (the cavity magnetron – now found in almost every western home in a microwave oven – was an essential innovation invented in 1940 and deployed to devastating effect in US and British planes for centimetric radar in the battle). And, of course, the greatest secret of all – the British/Polish cracking of the Enigma machine – was also central (the British got back “in” to the German navy enigma in December 1942).

Pykrete was part of this scientific battle – based around the idea of Geoffrey Pyke, the archetypal dotty scientist (and according to Wikipedia first cousin of Magnus Pyke, so amiable eccentricity  was plainly a family characteristic) . I first read of pykrete in Giles Fodden’s Turbulence – and to be honest the New Scientist article doesn’t take me much beyond the novel except to confirm some of the more bizarre episodes in the book (such as Mountbatten’s HQ being in cellars underneath Smithfield meat market) and the rather odd vignette of Canadian archivists claiming to know nothing of detailed plans they once bandied about 20 years ago (does someone fear Al-Q’ida or the North Koreans are building a pykrete boat?).

The New Scientist piece does suggest, though, that some of the wilder hopes for pykrete were misconceived, but in truth we still don’t know if it could or would be viable. By late 1942 the crack in Engima, combined with longer range aircraft, faster cargo ships, centimetric radar (which allowed much finer resolution and so made it easier to pick out U-boats on the surface)  and Leigh Lights meant that the balance of forces was shifting dramatically against the Kriegsmarine and the question of whether pykrete could have worked was rendered moot.

  • Anyone interested in the role of science in the Second World War would be well advised to see if they could pick up a copy of Brian Johnson’s Secret War: now 35 years old – and an accompaniment to the BBC series of the same name (which for the first time revealed the truth of “Station X” and the Enigma crack) – it is a tale of genius and daring-do and the good guys win in the end.
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The Great Alan Turing


Allan Turing Statue, on display at Bletchley Park

Image via Wikipedia

Slashdot have a story to the effect that Leonardo DiCaprio is to play Alan Turing in a film that will mark the mathematician’s centenary next year.

Great news – the man’s memory deserves nothing more than the actor who has proved himself to be both great and edgy in recent work (he’s certainly not the milque toast figure the start of his career briefly suggested.)

As a geek, of course, I hope that the film will try to explain, just a little his achievements.

But how can you explain the ideas of computability and the Church-Turing thesis in a popular film? A tough one, but I suppose you could do something.

The Bletchley Park “bombe” and the idea that the weakness of the German Enigma machine – that it would never map a letter to itself (eg., in any message “e” would never be encrypted as “e”) – could be used to break the code (if a combination of a guessed plain text, usually a weather report, at the start of the message , and the initial key settings produced code that mapped letters to themselves then the initial settings were wrong) – is probably easier to explain.

And don’t forget about SIGSALY, the voice encryption system Turing worked on with Bell Labs. As a piece of engineering this is probably impossible to over-estimate in importance: as the first practical pulse code modulation system it could even be said to be the mother the mobile phone, or at least its grand aunt.

And, of course, let me again plug my book of the year: The Annotated Turing: A Guided Tour Through Alan Turing’s Historic Paper on Computability and the Turing Machine

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