The Plausibility of Alien Life

There is another important signature to be seen by aliens. Our atmosphere contains a relatively large amount of oxygen. This is indicative of life, because without the constant replenishment of oxygen by plants, it would vanish very quickly from the atmosphere. Oxygen has been in our atmosphere in conspicuous amounts ever since photosynthesis evolved, I expect the aliens any minute now.

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

It depends on how you define life, of course. But I think we can at least agree that whatever causes so much oxygen in a planet's atmosphere is surely an interesting phenomenon.

Let me put it this way: if I were an alien looking at Earth, seeing that a large fraction of its atmosphere is oxygen, and knowing that without replenishment this would not be the case, I would think that something interesting is going on there. It could even be a form of life. Not my form of life, obviously, because I breathe liquid nitrogen, but still.

Hello Buz,We do know what happens when matter and antimatter meet: they annihilate one another and are completely converted to energy according to Einstein's famous formula E=mc².

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.