Aberrations; a lecture in Optics. 1

Optical systems are studied under two assumptions

object point does not lie far away from the axis of the optical system.

rays taking part in image formation make a small angle with the axis of the optical system.

The domain of optics where above two assumptions are valid is called as Paraxial optics. Paraxial systems are highly idealized and in reality do not perfectly represent the situation. The consequential errors in image reconstruction are known as aberrations.
The paraxial assumption can be represented by truncating at the first term of the polynomial expansion of the sin function by the Maclaurin series. More…

Blackholes and the Action Principle. Reply

This is not an article that purports to establish any link between what I have to say about Blackholes and what I have to say about Action Principle.

First off there are always a connection between action principle and anything else in Physics. Everything in principle can be derived from the action principle. The action principle is the general principle of all sorts of mechanics in Physics and has the weird power of superiority over everything else, at-least in principle. So if you want to claim something is inconsistent in Physics, take a piece of chalk and chalk out how it is that the action principle is inconsistent with anything that you want to discard. The action principle has the key to proving how consistent or inconsistent Physics is.

And I am not stating the action principle much, either. I just wish to mention two ideas that have no explicit connection to be brought out by this article. Hence they are to be read without any purported conjunctions of one with the other. More…


Optical Path and Fermat’s Principle. 4

In the last few weeks I am trying to understand why light traverses straight lines and why it refracts. The other day I saw a little mug floating inside a bucket full of water. Inside water any object would look shortened, a phenomena known as refraction. Thats because light rays would “bend” inside water (towards a direction where they have to take a shorter path) as their speed must reduce, given to the fact that in the same time in a rarer medium light would have traveled a longer distance in the exact same time, which is no longer possible due to the crowd of molecules and subatomic ghetto that it meets along its way. More…