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There has been much interest recently around the discovery of Earth- like planets. While thinking of the possibility of life on those planets, I came to the realization that assuming there is no life on those planets, given that they are Earth -like, seems to be an unwarranted assumption.

A planet with Earth - like geophysical features but with no life will have to have:

  • Water, but no water - based organism, even micro organisms
  • Water and land masses, but no vegetation, no plant life even on a microscopic scale
  • Organic molecules but no life

Is it reasonable to assume that the same processes that formed the Earth and other planets resulted in the creation of life on Earth but somehow did not result in creating life on other planets?

For those who believe that God created the universe, isn't it limiting God to imagine that He created Earth -like planets but stopped short of creating plant and animal life on those planets except on Earth?

This seems to me to be an artifical limitation place by us humans on how the universe develops.

stackex555
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  • You seem to be asking two questions; if it is a reasonable assumption to ... and isn't it limiting to God ... These are very different questions, please focus on one to narrow down the scope. The first question does not seem to be related to the philosophical concept of reason. To the second I cannot imagine what answer you expect besides yes or no. Can you please clarify what the philosophical issue here is? You can use the [help/on-topic] for guidance. –  Dec 06 '16 at 15:53
  • I agree I have two questions that are not closely related, also, this question is basically a sceintific one, although it relates to the train of logic applied to the process of the prediction of evolution of life. Appreciate the answers, though. – stackex555 Dec 07 '16 at 09:09

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You could approach this question from a chance perspective. Assuming life on earth formed by a chemical process and then a process of evolution, what's the chance that the same process has happened on other planets?

If the universe was infinite, there would be an infinite number of extraterrestial life forms, ranging from single-cell organisms to civilizations to life forms that extend the meaning of the phrase 'life forms'. If the universe is not infinite, and if you know the right variables I guess you could calculate how many and in general terms what sort of extraterrestial life forms there are.

How life formed on earth is far from completely explained. But some steps in this process have been explained, or discussed. It seems in the evolving of life there were events which were very unlikely. For instance: Simply the evolving from the single-cell 'bag of chemicals' to multiple-cell organisms took hundreds of millions of years, according to Nick Lane in the Radiolab podcast 'Cellmates'. I think the chance of a similar process of the forming of Earth-like life, elsewhere, is extremely small. The finding of a couple, or even thousands of Earth-like planets isn't enough by far to reasonably claim that there is extraterrestial life. But then again, I don't know how big the universe is and how many other Earth-like planets there are.

Lucas Johnston
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  • I think the turning point here is the discovery of Earth - like planets. I recall the Drake equation and revisions to it that sought to predict the number of planets that would host life - revisting the Drake equation and plugging in the new numbers for the probabaility of the number habitable planets should help the question. – stackex555 Dec 07 '16 at 09:21