What is the approximate number of galaxies in the known universe, assuming that the milky way has an average mass and that all of the mass in the known universe is in galaxies? the mass of the milky way is on the order of 1042 kg, and the mass of the known universe is about about 1053 kg?

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =