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19:52
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Q: When will the last unambiguous evidence of mankind disappear?

TheDyingOfLightHumanity just disappears tomorrow, let's say it is like the Thanos-snap but it kills everyone. How long until the last unambiguous evidence of our existence disappears? What was this last relic? The faint spectres of electromagnetic signals which will travel space forever, odd isotopes ratios and...

science-based extinction archaeology
Morris The Cat
Morris The Cat
What level of scrutiny are we talking about here? Are you asking how long until there aren't signs of human habitation that are visible from orbit, or how long till an archaeological dig can't find any evidence we were ever here.
Mark Olson
Mark Olson
The late, great Poul Anderson wrote a short story, "In Memoriam", on that subject. See <poulandersonappreciation.blogspot.com/2013/05/…> for a summary of it.
AlexP
AlexP
We routinely find fossils of ancient animals which lived hundreds of millions of years ago... And no species of large animals has ever reached anything remotely similar to our numbers.
TheDyingOfLight
TheDyingOfLight
@Mark Olson Sounds interesting and I in fact asked this question with something similar in mind.
Ash
Ash
Suggested viewing Life After People
John
John
19:52
@AlexP to be fair some species have but only for surviving a lot longer than we have.
Cyn
Cyn
The World Without Us is a must read. goodreads.com/book/show/248787.The_World_Without_Us
Cort Ammon
Cort Ammon
What if we left skeletons, instead of Thanos-snapping? How amusing might it be to have some poor future civilization come across the Smithsonian's prehistoric exhibits and find it as evidence that we roamed the planet along-side the dinosaurs!
loonquawl
loonquawl
might be the remnants last longer after a thanos snap than without. whatever humanity evolves into might be even more creative than we are, erasing the marks of the anthropocene under dense layers of progress
R..
R..
Regarding something like Voyager, the question is whether anyone would know where to look. Finding a small object outside the solar system when you don't know you're looking for it is basically going to be impossible...
SRM
SRM
@R.. There aren’t many stars in our part of the galaxy, and Voyager is on a fixed trajectory at this point. Barring a run-in with some rock out there, backtracking its path to Sol should be easy for millions of years.
R..
R..
19:52
@SRM: Backtracking seems plausible yes; I made no claim to the contrary. It's getting lucky enough to initially spot it that seems extremely unlikely. Maybe I'm missing something..?
SRM
SRM
Reading the answers makes me wonder: how long would it take humans to cover up our traces if we had reason to really work at it? Could we even get close to “leave no trace” if we decided to leave Earth and put it back to nature?
TheDyingOfLight
TheDyingOfLight
@SRM That's a really interesting question... You might wanna ask it.
SRM
SRM
@R.. ah. You said “know where to look”... I read that in the context of “they stumble on Voyager, now where to look for its makers?” I didn’t expect they would ever be “looking” for Voyager. Minor miscommunication between us. :-)
Draco18s
Draco18s
There was an XKDC what-if about "the last light left over from humans." Though given I can't find it, it must've been in the book. The answer eventually boiled down to gently glowing glass blocks of cesium-137. Ah yes, pages 61-67
Gnudiff
Gnudiff
@AlexP we also happen to know we have found fossils for less than 1% of species that lived on Earth. bio.libretexts.org/Bookshelves/Introductory_and_General_Biol‌​ogy/…
AlexP
AlexP
19:52
@Gnudiff: How many of the missing species were (1) large animals (2) with bony skeletons (3) numbering in the billions and (4) living all over the face of the Earth? All those four attributes are very important in the preservation of fossils.
Gnudiff
Gnudiff
@AlexP it seems to me not as important as the particular time they became dead. We have no fossils of around 15 million years, and we have fossils for species before that and after that. For contrast, human species (H.Sapiens) is considered around 300k years old.
AlexP
AlexP
@Gnudiff: Are you referring to Romer's gap? Recent discoveries show that better sampling of potential fossiliferous localities contributes to closing the gap.
alephzero
alephzero
@AlexP the total human population is irrelevant to the number of fossils, since unlike other species, humans dispose of their dead in ways which will not result in fossil remains (e.g. burial in aerobic conditions or cremation)

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