2 ms·Nothing travels faster than c but light sometimes travels slower than that.by praptak 6y agoNothing travels faster than c but light sometimes travels slower than that.saagarjha 6y agoAlways, unless you happen to have a way of making perfect vacuums ;)praptak 6y agoThat too, but I meant actual cases when it is possible to make things go faster than light in a given medium, see also Cherenkov radiation.