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If the world exploded, what proportion of the rocks floating in space would have evidence of life?
Pat French
Longdon-upon-Tern, Shropshire, UK
Much depends upon the variables. What kind of explosion? What is meant by “evidence of life”? What or who is attempting to interpret any surviving evidence?
Life has colonised all the niches on the planet that are available. Currently, the whole of the surface and certain places deep below it host life or show signs of its presence. However, Earth’s crust represents a lot less than 1 per cent of its mass. The layer that includes life represents considerably less than that.
An estimate of a survival rate for any indication of life would be a pure guess. The best guess is probably, “very little”. An explosion caused by an asteroid impact might leave something recognisable. A solar catastrophe might leave little.
Much also depends on what might be “evidence of life”. It is possible to imagine lumps of fossils, both micro and macro, surviving the blast. All sorts of bits and pieces might also make it. Lumps of worked iron and other metals might be read as indicators of life, as could even minute shards of pottery or worked stone.
It is possible that tardigrades and bacteria such as Deinococcus radiodurans could survive and live. (It would be interesting to know whether the investigating intelligent entity recognised them as survivors of our planet.)
Whoever or whatever discovered remnants of our planet, they would need to have a definition of “life” that included the sort of molecular organisation that Earth exhibits in its life forms. They would need to recognise that an inorganic remnant could come from work undertaken by such life forms.
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