The field-theory tag has no wiki summary.
2
votes
3answers
276 views
What is a nonlinear field?
I have read two possible definitions. A nonlinear field is
A field taking values on a manifold.
A field whose equation is nonlinear.
What do you understand by a nonlinear field or a nonlinear ...
3
votes
1answer
584 views
What is a chiral field?
I have not found a clear definition of this. A teacher told me that it was a field having some constrains but that is not very convincing for me. He told me also that some examples could be skyrme ...
11
votes
3answers
1k views
7
votes
1answer
363 views
Is Bose-Einstein condensate a good example of a classical massive boson field?
Physically, we know that a BEC has formed if a macroscopic number of bosons occupy a single quantum state. The wave-function $\Psi(x)$ of the latter, normalized to the total number of condensed atoms ...
9
votes
4answers
405 views
Why must the field equations be differential?
In Landau–Lifshitz's Course of Theoretical Physics, Vol. 2 (‘Classical Fields Theory’), Ch. IV, § 27, there is an explanation why the field equations should be linear differential equations. It goes ...
23
votes
9answers
2k views
What is a field, really?
There was a reason why I constantly failed physics at school and university, and that reason was, apart from the fact I was immensely lazy, that I mentally refused to "believe" more advanced stuff ...
7
votes
1answer
341 views
What corresponds to this Lagrangian density?
Is there a physical example of a field that would have the following Lagrangian density
$$
L= \sqrt{1+\phi_x^2 +\phi_y^2+\phi_z^2}
$$
where the subscripts denote partial derivatives and $\phi$ is a ...
8
votes
2answers
320 views
Quantizing EM field
Why when we quantize EM field, whe quantize the vector potential $A^\mu$ obtaining vectorial particles (photons) like the elastic field (phonons) and we can't quantize directly the EM-field tensor ...
5
votes
3answers
381 views
What are fields?
I'm following my first course in field theory and the professor began, like many books do, by introducing the scalar field. However, I am a bit hesitant about the physical idea of fields. My question ...
5
votes
1answer
270 views
formal framework for talking about 'minimal couplings'
usually on physical theories one would have Lagrangians or Hamiltonians with multiple fields; say, a vector $A_{\mu}$ and a scalar $\phi$ and one would postulate ad hoc a coupling between the fields ...
13
votes
4answers
1k views
History of Electromagnetic Field Tensor
I'm curious to learn how people discovered that electric and magnetic fields could be nicely put into one simple tensor.
It's clear that the tensor provides many beautiful simplifications to the ...
4
votes
1answer
493 views
Einstein's Field equations and impulse-energy tensor
I premise that I haven't yet studied General Relativity, but in Relativistic Electrodymaics I have knowed impulse-energy tensor of Electromagnetic Field.
I know in Einstein's equations there is ...
4
votes
2answers
846 views
What does a Field Theory mean?
What exactly is a field theory?
How do we classify theories as field theories and non field theories?
EDIT:
After reading the answers I am under the impression that almost every theory is a ...
