toxikitty | 10 years ago | on: An Introduction to Quantum Field Theory
toxikitty's comments
toxikitty | 10 years ago | on: An Introduction to Quantum Field Theory
It starts off with a spring mattress analogy (like the one in the linked article, but with more math) and goes on to more advanced material from there. I remember it requiring little background besides LinAl and multivariable calc.
toxikitty | 10 years ago | on: An Introduction to Quantum Field Theory
Depending on the field of science/engineering and the specific application, one might choose to work with electromagnetic fields, photons or a combination of both.
In the QFT framework, a photon is merely a quanta of the electromagnetic field. So photon based or EM field based approaches are just two ways of dealing with problems. Neither is more or less 'real' than the other.
At the risk of straying into quantum info territory:
- given all possible information about a collection of particles, you could compute the temperature. However, knowing the temperature doesn't allow you to determine info about particles uniquely (you can write down a density matrix, and not assign a pure state).
- the above doesn't hold for the case of particles and fields. Given a set of field frequencies and amplitudes, you could describe the positions of particles and probabilities of observing them. Given positions and probabilities of observing particles, you could compute the frequencies and amplitudes of the associated field.
We can describe any given set of particles (however big or small, however fast or slow) in terms of fields, and vice versa.
I like this comment :
When I studied quantum mechanics, my professor advised that I avoid the question "which is more fundamental?" and replace it with "which is more useful?".
From this stackoverflow link (http://physics.stackexchange.com/questions/122570/which-is-m...)
My QFT knowledge is rusty, so please correct me if I'm wrong.