In a recent article, mathematician Aczel argues convincingly that the number of planets su
The trouble starts when we come to estimate the probability that life will emerge on any of these planets. The problem is that we don' t have a good theory of the origin of life on earth. Without one, it is anybody' s guess how likely this event actually was. Out of thin air Aczel conjures (想像) the figure of 1 in a trillion for this likelihood and concludes that the probability of life existing on at least one other planet is virtually 1.
Statistics are extremely powerful and important, and Aczel is a very clear and capable exponent (倡导者) of them. But statistics cannot substitute for empirical (经验主义的) knowledge about the way the universe behaves. We now have no reasonable way of arriving at robust estimates for the probability of life arising spontaneously when the conditions are right. So, until we either discover extraterrestrial (外星球的) life or understand far more about how at least one form. of life--terrestrial life--first appeared, we can do little more than guess at the likely hood that life exists elsewhere in the universe. And as long as we' re merely guessing, we should not dress up our interesting speculations as mathematical certainties.
The term "Out of thin air" in Line 3 of Paragraph 2 can be best replaced by ______.
A.convincingly
B.confidently
C.groundlessly
D.suitably