快猫短视频

A FAMOUS computer model that tried to predict the level of chaos necessary to
kick-start life on Earth seems to have got the answer wrong.

Ten years ago, Chris Langton of the Santa Fe Institute in New Mexico used a
computer model to study environmental stability for living organisms. He used a
鈥渃ellular automata鈥� program, which divides an infinite plane into square cells
and populates the grid at random.

In the program, cells that are isolated die off because they cannot
鈥渞eproduce鈥�, while cells in overcrowded regions perish due to a lack of
resources. Only cells with a specified number of living neighbours survive and
multiply. A program based on these simple rules can produce 鈥渙rganisms鈥� made up
of many cells, which interact with each other in complex ways.

Langton then altered a parameter he called lambda, a measure of the size of
the region over which cells can be influenced by their neighbours. In effect,
lambda reflected the amount of chaos in their environment. If lambda was too
high, the collection of organisms became unstable, fluctuated wildly and died
out. If lambda was very small, the organisms survived, but the populations did
not change because there was so little competition.

Between these two extremes, however, there was a 鈥渟weet spot鈥� where the
organisms thrived, showing the sort of gradual evolution of life on Earth.
Langton claimed that the concept of lambda might shed light on the conditions in
which life arose.

But now Andrew Adamatzky of the University of the West of England in Bristol
has cast doubt on Langton鈥檚 finding. When Adamatzky repeated Langton鈥檚
experiment, he found cellular automata which had a series of lambda values
outside Langton鈥檚 critical range.

鈥淭here is nothing special about these regions of lambda,鈥� says Adamatzky. He
concludes that lambda reveals little about the real world. His work will appear
in the autumn issue of Chaos, Solitons and Fractals.