Hi,(adsbygoogle = window.adsbygoogle || []).push({});

a few lines below equation (3.1.5) Weinberg writes:

"The transformation rule (3.1.1) is only possible for particles that for one reason or another are not interacting."

I thought a lot about it, but dont see any possible reason. Can you help please?

After a few lines he defines the states [tex] \Phi_{\alpha} [/tex]

then these one should transform like (3.1.1). But why?

Thanks a lot

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Weinberg QFT I: Lorentz Transformation with interaction

**Physics Forums | Science Articles, Homework Help, Discussion**