Sunflowers to test Turing theory

Sunflower

Thousands of sunflowers are to be planted in Greater Manchester to try to prove a theory put forward by a mathematics genius.

Alan Turing, who helped crack the Enigma code in World War II, was fascinated by mathematical patterns found in leaves and seeds.

His theory that sunflower heads featured Fibonacci number sequences was left unfinished when he died in 1954.

Professor Jonathan Swinton said a "big dataset" was needed to prove it.

He said Turing's theory had been "along the right lines".

Fibonacci numbers are a sequence which begins with zero and one, where each is the sum of the two numbers before it.

The appearance of patterns in the phyllotaxis - the arrangement of leaves, stems, seeds or similar - has been studied by many well-known scientists, including Leonardo Da Vinci.

Turing's study of the seed patterns in sunflowers followed that of a Dutch academic, JC Schoute, in 1939, who studied 319 samples before theorising his own conclusions.

Turing, who directed the computing laboratory at the University of Manchester and helped to form the basis for the field of artificial intelligence, wrote a paper in 1951 on form in biology and went on to work up a specific theory to explain why Fibonacci sequences appeared in plants.

However, he never had chance to test his theory, as he was convicted for gross indecency in 1952, when homosexual acts were illegal in the UK, and committed suicide two years later.

The only surviving programs which he wrote for the Manchester Mk1, one of the world's earliest modern computers, are devoted to proving his theories.

Over 3,000 sunflowers will be planted to help try and prove his theories in Turing's Sunflowers, a mass-participation project run by the Museum of Science and Industry, Manchester Science Festival and the University of Manchester.

Prof Swinton, who helped develop the project, said the mathematician had tried to use the Fibonacci sequences in sunflowers "as a clue to help understand how plants grow".

"Since then other scientists believe that Turing's explanation of why this happens in sunflowers is along the right lines but we need to test this out on a big dataset, so the more people who can grow sunflowers, the more robust the experiment," he said.

Project manager Erinma Ochu said the sunflowers would "provide the missing evidence to test his little-known theories about Fibonacci numbers in sunflowers."

She added that it would be "a fitting celebration of the work of Alan Turing".

The results of the experiment will be revealed at Manchester Science Festival in October.

This year marks the centenary of Alan Turing's birth. The occasion is being marked by a series of events around the world, including a commemorative postage stamp issued by Royal Mail.