Rigorously work out how long each of those components would last under even ideal natural circumstances. Silicon doesn't devitrify like glass. But it will weather away, atomically, chemically and physically.
They may have been around for 1000x longer than humans but the billions and billions of tons of gold, copper, and other native metals will be obvious non-degradable remnants that will survive us for hundreds of millions of years. Any metal that can be found in its native form will survive for a very, very long time and the list of such metals is long. We already know that stone tools from archaic human and apes easily survives for millions of years.
The Keweenaw copper deposits [1] where copper is mined in boules and nuggets far larger a strand of copper wire is about a billion years old. That's how long our bulk metal artifacts will survive, despite rigorous geological activity. Those artifacts already number in the hundreds of billions if not trillions. The only reason they don't already litter the planet like ancient pottery and arrow heads is that they're highly recyclable and reusable.
> But I expected HN’s responses to be a touch more thought through.
We've just been talking past each other which is par for the course for HN.
Does that challenge that we only have fossils for “only a handful of individual animals across thousands of taxa per 100,000 years”?
Less than 0.1% of species wind up in the fossil record [1]. (I’ve heard but can’t reliably source 5% for animals.)
Most of those species existed far longer than we have. Hence why the astrophysicists who came up with the hypothesis ruled out fossils, much less fossils that would show evidence of industrial civilisation.
> no doubt human civilization is leaving its own behind that will be detectable millions of years from now
Sure, 2+ million, per the paper that sparked this.
[1] https://www.bbc.com/future/article/20180215-how-does-fossili...