The Casimir Effect

In my previous article on Quantum Fluctuations I discussed about the vacuum fluctuations and virtual particles, I explained how these crazy ghostly particles are created and show there effect in our visible universe. With this article I am also opening a new section of website named as ‘Quantum Field Theory’ as this is a part of that portion of Quantum-verse.

In today’s article, I am going to show a practical experience of an action resulted by these virtual particles.

Imagine you have two uncharged parallel plate just a few nanometres apart and someone asked you what effect those plates will feel when they remain uncharged??? Then you answer according to the classical physics will be like: Those plates will not feel any effect as they are uncharged….right????

Nope, that’s wrong. Surprisingly, when you observe those plates you will find that those plates are attracting each other even when they are uncharged. This is known as Casimir effect.

Exceptional…right……But that’s truth!!!

The correct explanation was given by a Dutch physicist Hendrick Casimir in 1948 based on the uncertainty principle of time and energy. This is the effect which proves the existence of virtual particles.

Casimir correctly showed that if we place two uncharged plates few nanometres apart then they will attract each other due to vacuum fluctuations.

So, they are attracting each other???

As we have seen in my previous article on virtual particle and vacuum fluctuations that virtual pairs of particles and antiparticles are being created constantly, here also they are constantly created between and around the plates. However, for a virtual pair to be created between the plates, its wavefunction must have a relatively small wavelength as greater wavelengths do not fit between the plates. So, as a result less no. of virtual particle are created as compared to other places around the plates, where the particles of any wavelength can be created.

So, this results in a greater pressure on the outside of the plate than on inside. This results into the attraction of the plates even when they are uncharged.    

So, is there any other possible explanation for Casimir Effect???

Surprisingly yes…..

In 2005, Robert Jaffe of MIT showed that Casimir effect can be explained without the above theory. According to him they are relativistic, quantum forces between charges and currents. The Casimir force is simply the relativistic and retarded Van der Waals force between the plates. In 1978, Schwinger, Deradd and Milton published a similar derivation for the Casimir Effect between two plates.

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                                                                    -Ratnadeep Das Choudhury

                                                      Founder and Writer of The Dynamic Frequency