Think of a cell sized ant sitting on a huge grid of such white cells. The thing to note about this ant is that it follows a certain sets of simple rules. The main rule is that when the ant exits a cell, it inverts the colour of the cell it just left. Besides that:
If the ant enters a white square, it turns left.
If it enters a black square, it turns right.
Here’s what happens if the ant starts out in the middle and moves to the cell on the right, as a starting step (this can be on any side).
Now as this continues, a seemingly random figure starts taking shape. The black cells are in total chaos, there seems to be no specific order to how they appear on the canvas. (of course the pattern is always the same chaos, considering the ant starts on a blank array of cells).
And yet, after about 10,000 steps are completed by the turing ant, it starts creating a very orderly highway kind of figure on the canvas. It enters an endless loop consisting of 104 steps which keeps repeating for ever and creates a long highway kind of structure.
Suppose, initially you take a configuration of black spots on a canvas (not a blank white canvas). Take an array of cells with randomly arranged black spots, for instance. If given enough time, the ant ultimately always ends up making the looped highway. However, before it starts doing it, it might take a significant amount of steps less, or more, than the ~10,000 steps it took to reach the loop in a blank array of cells.
No exception has ever been found. A computer scientist Chris Langton discovered this in the year 1986.
In the year 2001, between 25th July and 25th September, people from the Indian state of Kerela (Kottayam and Idukki districts) experienced a bizarre oddity – The Red Rain of Kerala. Sporadic heavy downpours of mysteriously colored water left the people of Kerala dazed. More recently, red rains were also seen in parts of Sri Lanka between 15th November and 27th December, 2012.
Yellow, Black and Green rains have also been reported several times since 1896.
Red Rain of Kerala – Studies
A study conducted in India showed that the rain was colored because these raindrops contained millions of spherical and oval red particles which had an internal structure. These things looked like biological cells. Initially, when scientists weren’t able to confirm the existence of DNA (a fact which has baffled scientists) in them, in spite of an internal structure present in the cells, some started claiming that the origin of these red particles was extraterrestrial, possibly, coming from an exploded meteor.
Later the mystery was solved, the presence of DNA was confirmed and a study, destroying popular media claims, concluded that the red rain of Kerala had been colored due to airborne spores originating from a type of algae. There was nothing alien about it.
The unusual color of the rain was due to the presence of a unicellular micro-organism belonging to Kingdom Protista, of the Phylum Euglenozoa, known as Trachelomonas. Trachelomonas was the main cause of reddish downpours in other regions of the world as well.