Habitable worlds with no signs of life
Habitable worlds with no signs of life
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DOI：
10.1098/rsta.2013.0082
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发表时间：
2014-04-28
期刊：
影响因子：
5
通讯作者：
Cockell, Charles S.
中科院分区：
文献类型：
--
作者：
Cockell, Charles S.
“宇宙中大多数可居住的世界将没有可远程检测到的生命迹象”被提出作为一个生物学假设，将在系外行星的研究中进行测试。在宇宙的其他地方也可以发现可居住的行星，但有许多假设的情况是，在这些行星上寻找生命可能会产生负面的结果。没有远程可探测到的生命特征的可居住世界的场景包括：可居住但没有生物圈的行星（无人居住的可居住世界）;有生命的行星，但缺乏任何可检测的生命表面特征（提供实验室示例）;和有生命的行星在这些地区，生物群产生或清除的大气气体浓度不可能与非生物过程分开，因为缺乏行星状况的详细知识（“系外行星热力学不确定性问题”）。拒绝这一假设将需要生命的起源通常发生在可居住的行星上，光谱可检测的色素和/或代谢产生明确的生物特征气体（例如。G.这些生物（光合作用）通常会进化，并且庇护它们的生物通常会获得足够的生物量，以产生外星天文学家可以检测到的生物特征。
'Most habitable worlds in the cosmos will have no remotely detectable signs of life' is proposed as a biological hypothesis to be tested in the study of exoplanets. Habitable planets could be discovered elsewhere in the Universe, yet there are many hypothetical scenarios whereby the search for life on them could yield negative results. Scenarios for habitable worlds with no remotely detectable signatures of life include: planets that are habitable, but have no biosphere (Uninhabited Habitable Worlds); planets with life, but lacking any detectable surface signatures of that life (laboratory examples are provided); and planets with life, where the concentrations of atmospheric gases produced or removed by biota are impossible to disentangle from abiotic processes because of the lack of detailed knowledge of planetary conditions (the 'problem of exoplanet thermodynamic uncertainty'). A rejection of the hypothesis would require that the origin of life usually occurs on habitable planets, that spectrally detectable pigments and/or metabolisms that produce unequivocal biosignature gases (e. g. oxygenic photosynthesis) usually evolve and that the organisms that harbour them usually achieve a sufficient biomass to produce biosignatures detectable to alien astronomers.