A question regarding Schwinger's Sources' Theory

[MathematicalPhysicist]

I was under the impression (false one appraently (I read Lubos Motl answer in stackexchange)) that Schwinger's theory which is covered in his three volumes called "Particles, Sources and Fields.", is really only a different interprataion to QFT, but the end results are the same.

Now I read the special preface of volume three and it's written that:"
...Particular attention should be directed to Section 5-9, where, in a context somewhat larger than electrodynamics, a disagreement between source theory and operator field theory finally does appear."

So does Schwinger's theory genuine different than QFT?
Unfortunately I don't have time now to read thoroughly his three volumes, maybe after I am done with my PhDs.

 

[eljose79]

Hello,

Thank you for bringing up this interesting question. As a scientist who is familiar with both Schwinger's theory and QFT, I can provide some information to clarify the differences between the two.

Firstly, it is important to note that Schwinger's theory is not just a different interpretation of QFT, but it is a distinct theory in itself. While QFT is based on the concept of fields and their interactions, Schwinger's theory is based on the concept of sources and their interactions.

In QFT, the fundamental entities are the fields, which are defined at every point in space and time. These fields interact with each other through various interactions, such as the electromagnetic, strong, and weak forces. On the other hand, in Schwinger's theory, the fundamental entities are the sources, which are localized in space and time. These sources interact with each other through the exchange of virtual particles.

One of the main differences between the two theories is the approach to calculating physical quantities. In QFT, calculations are done using Feynman diagrams, which represent the interactions between fields. In Schwinger's theory, calculations are done using Green's functions, which represent the interactions between sources.

In terms of the end results, while QFT and Schwinger's theory may yield similar predictions for some physical quantities, there are also cases where they differ. This is due to the fact that the two theories have different underlying assumptions and mathematical frameworks.

In conclusion, Schwinger's theory is indeed different from QFT, and it is not simply a different interpretation of the same theory. However, both theories have been extensively tested and have been found to be in agreement with experimental results in many cases. I hope this helps to clarify the differences between the two theories.