I just watched a talk from George Ellis about cosmology. I believe there is a serious double standard implied in it. He says (A) the universe is fine tuned for life. Change one of the constants of nature like the mass of the electron and you wont have life in the universe. He also says (B)the multiverse might explain this fine tuning, but the multiverse is based on extrapolating physics to unknown realms that we cant observe and is therefore questionable science. However doesnt the statement (A) that life cant exist unless we have these very finely tuned constants also depend on extrapolating physics into realms we cant observe? After all no one can ever do an experiment whereby we change a constant of nature and then see if life still emerges. Perhaps changing one constant leads another to move to compensate, who knows? The conclusion of fine tuning seems to be based on just such an an unverifiable extrapolation that Ellis accuses the multiverse proponents of being guilty of . it seems to be if we allow for such extrapolations then both A and B can be fair game, but if we don't then neither A nor B is fair game.