Great Legacy

If you just hang on for a while to contemplate deeper in quantum field theory, you would always end up believing in magic!!...
Neither the negative frequencies, nor the infinite amplitudes can stop us from defining it rigorously!
The on set is so vague that you can barely think of getting anywhere... However, thanks to the theoretical physicists of the twentieth century, not only we can form a self-consistent formalism, but also, the theory itself provides us answers to the questions that at the beginning we weren't even brilliant enough to ask!
I should confess that I am totally fascinated by its power...
From the sneaky analytic continuation, to the idea of a perturbation theory with divergent terms in orders higher than one, you can never guess what a fantastic new physics is waiting for you... Then it comes the renormalization, and all of a sudden, all the ambiguity becomes lucidity.

It is a great legacy of physicists of the twentieth century. We should wait and see what is coming up in the new century!