When two quantum objects interact, all the information they carry becomes scrambled. Now, physicists have calculated a fundamental limit for how quickly this can happen.

One striking example of information scrambling happens in black holes, says Victor Galitski at the University of Maryland. When objects fall into these super-dense bodies, some of the information they contain reemerges in the black hole’s emitted radiation – but in a highly scrambled form.

In fact, physicists have theorised that black holes…