It doesn't though. It only requires for life to have evolved on another planet, reached space and then potentially traveled lightyears through space to reach earth.
Space is really fucking empty. Seems less likely than throwing a rock out of a rocket on the way to mars and hitting a random bucket, without looking. Add to that that it would require life having evolved while the universe was younger and different to the only state of the universe that we know to support life.
Is it impossible. No. But at that point the theory has as much explanatory power as creationism, i.e. none.
Space is really fucking empty. Seems less likely than throwing a rock out of a rocket on the way to mars and hitting a random bucket, without looking. Add to that that it would require life having evolved while the universe was younger and different to the only state of the universe that we know to support life.
Is it impossible. No. But at that point the theory has as much explanatory power as creationism, i.e. none.