There's a pretty neat thought that as stars progress through their life cycle, creating elements, and finally exploding, that all the elements contained on our earth has been "processed" in one or even several stars at some point in the past. That means that we are all made up of basic elements created in stars of the past. Then eventually when our star consumes us or whatever our end planets end is, that whatever basic elements are here.. including the ones that make up our bodies will be redistributed through some other corner of the universe.
It's possible that this very second you could contain elements that were in some alien race billions of years ago.. That, or that billions of years from now, you could be part of some other Plantet, asteroid, star, even being.
It's one thing to take Distance into account when you think about other life.. but take into account time, and the chances we are alone, become even more... astronimical....
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