Basically, if the size of the event horizon(EH) of a blackhole is R (radius) can the rate of change of this R or dR/dt be faster than the speed of light(c)? When it comes to expansion of an EH of a blackhole: Does the event horizon immediately expand? For example, if one black hole consumes another, how long does it take for the new horizon to form? or for example, if a blackhole swallows a massive object very fast, can its event horizon expand faster than c? WHen it comes to contraction of the EH: We know that only hawking radiation as of yet contracts the blackhole EH. So if the blackhole is small enough, will the decrease in the blackhole EH radius be maxed at c? How does it work? For those of you who may say that it depends on the charge and rotation of the blackhole, assume a simple static one. I don't know the math.