Imagine 10k years in the future. 2 aliens arrive on earth, and examine the rubble. "Hey, check it out. They were right on the cusp of developing stardrive". "We

Imagine 10k years in the future. 2 aliens arrive on earth, and examine the rubble. "Hey, check it out. They were right on the cusp of developing stardrive". "Weird, what happened? Nuclear war? Climate change?" "Nah, looks like they just couldn't work the math out, so they gave up."