There is no collapse. One can create pairs of entangled particles and send streams of these in opposite directions - left and right for example. When particles on the left are measured, it causes the so-called collapse of the wave function and that of its paired particle that went to the right. This means one can "collapse" the wave functions of one stream of particles (right) by taking measurements of the other (left). The thing is, the particles on the right behave exactly the same way regardless of weather their wave function has been collapsed. In other words, no one can tell if this collapse has even occurred. Why is it talked about as a discrete event?