- #1
HomogenousCow
- 737
- 213
I'm a beginner in QFT and I'm always hearing people say that QFT is undefined in 3+1 dimensions or that the Hamiltonian cannot be rigorously defined, what do these statements mean exactly? In particular I'd like to know what makes the 3+1D case that much worse than non-relativistic QFTs like the ones in condensed matter theory, or even just regular QM where perturbation series can also be divergent (and almost always are). Thanks.