“Yes, but I think that scarcely likely, for I have often experimented with motes in a sunbeam. If these are agitated in vacuum, they rise and fall and float around but never collide. At least I have never been able to cause any to do so; many draw near to each other, but long before they get sufficiently near to touch, they fly off horizontally and fall. So long as they float in space they will not collide; only is it possible for them to do so when they reach the fixed point to which they have been drawn. The motes will rest upon one another when they have reached the lowest part to which gravity has drawn them, but so long as they are above that part, I cannot cause them to collide, no matter to what agitation they are subjected. They float and dart here and there in the sunbeam as separate units—stars if you like—each avoiding contact with its neighbour, though the sizes are unequal.” “Then how could a sun form? I could understand the worlds separating if all the forces are equal, for in that case one would repel the other, but if they cannot collide, how can they form a sun by coalescence?” “Though two worlds could not collide accidentally in space, one could draw the other to its own surface, if powerful enough to do so, the impact causing such heat as to liquefy both.” “Is not that the same thing as colliding in space?” asked Godfrey, dubiously. “I must confess I see no difference.” “No, not at all,” said Sorrel, smiling, “I will illustrate the point by a simple experiment I have often used to prove this very question to my own satisfaction.