What is quantum field theory trying to explain?

[Radarithm]

The title says it all. I'm sorry if you get annoyed because of my "noobishness", but I'm still a physicist in training (taking undergrad Classical Mechs). I'm really interested in Quantum Theory and I keep hearing about Quantum Field Theory, but not a single website accurately explains what it is (again, I'm a noob). I'm not as smart as you guys, so please use layman terms if you can

 

[kith]

In ordinary quantum mechanics (QM), you treat particles quantum mechanically.

In quantum field theory (QFT), you treat fields quantum mechanically. It turns out that in addition to the classically known fields (like the electromagnetic field) there are new "quantum fields" for all fundamental particles (like the electron). In this sense, QFT is more fundamental than ordinary QM. The most fundamental theory up to date -the Standard Model of particle physics- is a QFT.

 

[Radarithm]

In ordinary quantum mechanics (QM), you treat the quantum mechanically.

In quantum field theory (QFT), you treat fields quantum mechanically. It turns out that in addition to the classically known fields (like the electromagnetic field) there are new "quantum fields" for all fundamental particles (like the electron). In this sense, QFT is more fundamental than ordinary QM. The most fundamental theory up to date -the Standard Model of particle physics- is a QFT.

Thanks for the explanation! It's the simplest and clearest one I've read.

 

[kith]

You are welcome. ;-) Don't hesitate to ask further questions.

(also note that I forgot the word "particles" in the first line, I have edited it)

 

[VRT]

Also it considers relativity: quantum mechanics + special relativity = quantum field theory.

 

[DrClaude]

[STRIKE]I would like to add the important fact that QFT was necessary to allow for particles to be created and annihilated, which isn't in the framework of the original quantum mechanics.[/STRIKE]
What Jazzdude said below.

 

[Jazzdude]

I would like to add the important fact that QFT was necessary to allow for particles to be created and annihilated, which isn't in the framework of the original quantum mechanics.

That's not really accurate. You can use the Fock space without the 2nd quantization of the fields to incorporate processes with variable particle numbers.

Cheers,

Jazz