For quantum field theories coupled to any massless fields, one generally encounters “IR divergences” which arise due to the fact that the asymptotic description of the state contains an infinite number of soft radiative quanta. These quanta have recently gained interest due to their connections to unitarity, asymptotic symmetries and the memory effect. However, for the description of any bulk experiment, these quanta are generally viewed as a nuisance with little physical relevance for the predictions of any bulk, finite time observable.

In this talk, I will explain that this is not the case. In fact, the situation is quite the opposite: all local physical observables and phenomena depend on the entanglement and absorption of soft radiation. I will explain (1) how this phenomenon arises and (2) why it was missed in the literature and (3) why this result agrees with the predictions of collider experiments. I will primarily focus on the case of QED with and will comment on the analogous issues in QED with massless electrons, Yang-Mills theories and Quantum Gravity.