The theory which is loved by every scientist around - THE PERTURBATION THEORY

Yes, this theory is opted by almost all the scientist and observers of different disciplines especially the domains which cannot give well-defined experimental results. This approach was given by Paul Dirac in 1927. It was later named as the Fermi's golden rule.

Perturbation Theory is a mathematical analysis to find an estimated solution from the exact solution to the similar and simplest problem.

THE BASIC IDEA BEHIND THE PERTURBATION THEORY

This simple example can cheer you up:

While making the tea we don't take a weighing machine to calculate the amount of tea powder to add to the milk boiling. We just take an approximate amount which we feel perfect.

This happens in science too !!!

As to understand this amazing approach in a more comprehensive mode we have to know a little mathematics.

The sine series 

This is the graph of a sine function.

The series equation is 

  

Here we take the expansion of sine series.

For a given value of x and computing it in x or in x - (x^3)/3! we can get a fair answer.

This is how the perturbation theory works.

For more transparency, we take the example of the shape of the earth.

We are taught in our schools that the shape of the earth is spherical with a radius of 6400km

 But it is not exactly spherical if we consider all the factors into account.

The rotation of the earth around its axis influences the distance from the poles and the distances from the equator from its centre.

The distances from the poles and equator to the centre of the earth turns out to be 6357kms and 6378kms respectively. The diameter is of the Earth is 42kms fatter than it is tall. The difference is only about 0.3% or 1/300th part.

Recognizing the Antarctic ice sheet squishing the bottom of the Earth and other effects the North pole bulges upwards about 17mts and makes a bulge of 7mts in mid-southern latitudes.

This method has given countless unsolvable enigmas with satisfactory answers and is still being used by everyone around the world.

Hope it was helpful!

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