  How much time does a wave packet spent in tunneling a barrier? Quantum
mechanical calculations result in zero time inside a barrier. In the nineties
analogous tunneling experiments with microwaves were carried out confirming
quantum mechanics. Electron tunneling time is hard to measure being extremely
short. However, quite recently the atomic ionization tunneling time has been
measured. Experimental data of photonic, phononic, and electronic tunneling
time is available now. It appears that the tunneling time is a universal
property in the investigated time range of twelve orders of magnitude.
