In 1972 Edward N. Lorentz a meteorological professor at
MIT presented a talk in the 139 meeting
of the American Association for the Advancement of Science held in Washington
entitled
“Predictability –Does A Flapping of Butterfly wings in
Brazil set a tornado in Texas.”
This generated a lot of discussion among the researchers and
academicians about its absurdity but the powerful message of the talk was that
the behaviour of the atmosphere is unstable with respect to the perturbations
of small magnitude. This gave rise to what is known as Butterfly Effect and is
a concept given by Lorentz to highlight the possibility that small causes may have
momentous effects. He always stressed that there is no way of knowing exactly
what tipped a system. The butterfly effect is a symbolic representation of an
unknowable quantity.
The statisticians he worked with thought it would be
possible to predict weather, weeks or months away by sourcing the historical
records to see what happened previously when conditions were the same. Lorentz
was skeptical of the idea and he argued that the atmosphere is too complex and
that it never repeats itself. So it would be impossible to find a day in the
history when conditions were precisely the same and he did discover that even
small differences in the initial conditions can lead to vastly different
outcomes.
The butterfly effect is the sensitive dependence on initial
conditions in which small changes in one state of deterministic non liner
system can result in large differences in a later stage. In 1961 Lorentz was
running a numerical computer model to redo a weather prediction from the middle
of previous run as a short cut. He entered the initial condition of0.506 from
the printout instead of entering the precise value of 0.506127. The result was
a completely different scenario. He published a paper in 1969 and proposed a
mathematical model for how tiny motions in the atmosphere scale up to effect
the larger systems. He found out that the system in the model could only be
predicted up to a specific point in future and beyond that reducing the error
in the initial conditions would not increase the predictability (as long as the
error is not zero). This demonstrated that a deterministic system could be
observationally indistinguishable from a non deterministic one in terms of
predictability.
History is full of such small changes which later led to
bigger events. Bombing of Nagasaki instead of Kuroko due to cloud cover,
Academy of Arts rejecting Adolf Hitler’s application, Cuban missile Crisis,
Chernobyl disaster, Indian naval mutiny of 1946 and departure of British, rise
of sea temperature and frequency and intensity of cyclonic storms, emergence of
Bangladesh, etc are some of the historical example.
The strong dependence of Indian Monsoon on the El -Nino, a
warming of sea of the coast of Chile is well known. If affects the onset,
progress and strength of monsoon. Recently as per the reports the spread of
corona virus which started from Wuhan to the world and leading it to declare as
a Pandemic is another example. In terms of Indian economy the massive reforms
undertaken by the Central government during the lock down can be cited another
examples as these changes will have a very long term effect and bring significant
changes in the Indian Economy in future.
