Note Hawkings preposition Its to not by Also note that the on Earth seems to be your personal interpretation  its really quite hard to heat anything to K on Earth because you wont find anything that needs heating Also note that your or Hawkings math is a bit off C is only K Since the CMB is roughly K it would heat a pizza in otherwise empty space to C unless my math is off which is a very real possibility at any time but especially when I lecture about other peoples shortcomings