The Star-Nebula Theory.

To give a single instance of this we may notice that even to-day the most popular theory of Novae is that each is caused by a star entering a nebula. The star is supposed to be stopped in a few days, or even in a few hours, by the resistance of the nebula. This theory leaves the sudden fading completely unexplained, but probably this is of no importance, for, with the accepted average density of a star and a nebula respectively, we are asked to believe that each atom of the latter is able to stop suddenly the headlong rush of 31/2 millions of millions of times its own mass.