居住行星的大小分布
The Size Distribution of Inhabited Planets
摘要：
类地行星有望为探测太阳系以外的生命提供最大的机会。然而，我们的星球不能被视为公平的样本，特别是如果其他地方存在智慧生命的话。就像一个人的原籍国是国家之间的一个有偏见的样本一样，他们的原籍星球也可能是行星之间的一个有偏见的样本。这种影响的程度可能是巨大的：世界上98%以上的人口生活在一个比中位数大的国家。在一个简单的模型的背景下，平均人口密度是不变的行星大小，我们推断，一个给定的有人居住的行星（如我们最近的邻居）有一个半径$r<1.2 r_\oplus$（95%的置信区间）。我们表明，这一结果可能不仅适用于拥有高级生命的行星，而且适用于那些拥有原始生命形式的行星。对影响种群大小的任何变量都可以作进一步的推论。例如，由于人口密度被广泛观察到随着体重的增加而下降，我们得出结论，大多数聪明的物种预计将超过300公斤。
英文摘要：
Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar System. However our planet cannot be considered a fair sample, especially if intelligent life exists elsewhere. Just as a person's country of origin is a biased sample among countries, so too their planet of origin may be a biased sample among planets. The magnitude of this effect can be substantial: over 98% of the world's population live in a country larger than the median. In the context of a simple model where the mean population density is invariant to planet size, we infer that a given inhabited planet (such as our nearest neighbour) has a radius $r<1.2 r_\oplus$ (95% confidence bound). We show that this result is likely to hold not only for planets hosting advanced life, but also for those which harbour primitive life forms. Further inferences may be drawn for any variable which influences population size. For example, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300kg.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
