We discuss phenomenology of extra time dimensions in a scenario where the standard model particles are localized in \our" time, whereas gravity can propagate in all time dimensions. For an odd number of extra times, at small distances, the (real part of the) Newtonian potential is \screened" by tachyonic Kaluza-Klein gravitons. In general, the gravitational self-energy of objects acquires an imaginary part. This complexity may either be interpreted as an amplitude for the disappearance into \nothing", leading to the causality and probability violation in low-energy processes, or as an artifact of the ctitious decay into the unphysical negative energy tachyons.Never mind how you fit it in, I just want to know how you can read that stuff! "Tachyonic Kaluza-Klein gravitons!" Then, if you can wade through the English, there's the math!
I'll wait for the layman's version. ;)
A little tidbit though, the Kaluza-Klein theories are the basis for superstring theory and the reason why people speak of the extra dimensions being all rolled up into tiny vibrating strings. Actually it is not necessary to visualize an extra time dimension as compactified.