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This brings up a thought I've had repeatedly (an admittedly unscientific one) when considering human history.

Considering that it "only" took us several thousand years to transform ourselves from hunter-gatherers to our current technologies, it makes little sense that this is the first human culture to reach the point we've reached. Then I try to dissuade myself from such a notion, rationalizing that if that were the case, we'd know it from some sort of evidence by this point.

And yet, I still can't shake the notion that this "shouldn't" be the first time around. Weird, especially since I consider myself a hardcore skeptic.

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What about artificial satellites? If their orbits were stable, shouldn't any satellites from previous civilization still be around? Do you have an estimate on the attrition rate from random meteor collisions and the like? We should be able to do pretty well just from our own experience.

It's as likely that a different civilization would go all-wired/wired-only for mass communication and only use satellites for observation purposes and GPS purposes. Then the number of potential satellites to be found is much lower than our current civilization.

Unless previous civilizations deliberately left no trace a la Star Trek Prime Directive. Or we're unable to perceive their interactions because of some perceptual blindness. Fun to think about.

I can't think of the name of the theory, but the general idea is that it would be very difficult to rebuild to our current level of technology after a cataclysm event because all of the easily reached surface resources required to bootstrap it have been picked clean. Even the near-surface resources are gone, requiring us to use massive open-pit mines or deep mining/drilling.

Some material could be recycled from crumbling cities I imagine, but even recycling most modern materials requires a certain minimal level of technology, no?

Even stranger, our sun has collapsed and been rebuilt at least once (estimates are 3 times). Makes you wonder how many civilizations could have been built.

More specifically to your comment, even on our planet, the evidence of civilization would be hard to find if there was a civilization several million or even a few hundred thousand years ago.

"Dust to dust"

Our sun has collapsed and been rebuilt at least once?

Google search for "sun collapsed rebuilt 3 times" lists Stonehenge, which seems to indicate Google can't find anything on the subject. I really don't understand what you're saying.

Can you please elaborate?

I think it's a reference to the supernova that occurred before our sun existed, which created the seed material for the sun to form from. It had to have happened because there are heavy elements on earth that only form in a supernova.

You can probably determinate the number of supernovas/hypernova/etc that happened before the sun by analyzing the proportions of different elements in the solar system and then use the various equations to compute how many explosions you would need to create the heavy elements (heavier than iron) that are observable since they are mostly created in these situations.

You probably can get these equations by analyzing nebula composition and the type of star which was there.

Also, the type of star gives an indication of it's history.

When I was a kid I remember imagining that the dinosaurs managed to create an advanced civilization, reaching the moon, creating cities, tried to harvest asteroids but accidentally wiped themselves out after a major mistake, eliminating the evidence for their civilization in the process.

This was after reading The Crucible of Time by Brunner (one of my favourite books)

I don't think even our current civilization could rebuild what we have. The easily-extracted fossil fuels are spent. Even if we haven't reached Peak Oil, we need increasingly more advanced technology to find and extract fossil fuels.

Can you elaborate? Before we were hunter & gatherers, we were monkeys, before that there were dinosaurs, before that there were one-cell organisms.

If there were human civilizations a million years ago or before that, there would be significant evidence of cities, just as there is evidence of dinosaurs, no?

I guess the way I'd put it best in terms of what you've asked is: "what if we (humans) are on our second, third, or nth attempt to create a sustainable technological culture, all previous attempts met with ruin or we were forced back into a 'pre-technological' hunter-gatherer lifestyle."

It's hard to put into words because it goes against everything I know or believe, and yet there's this little thought in my head that won't go away: "this cannot be the first time." Normally with UFOs or other sorts of "pseudo-reality" I would just write the thought off as an interesting weirdness of our world, but for some reason I can't. Might just be a personal failing ;)

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