In some book by P G Wodehouse (inventor of Jeeves the butler), one character says (out of nowhere) that all the humans on the planet could fit in a cubic hole 1/2 mile on each side. It took me a little while to convince myself that was true. It still is, apparently
There was a great post on this subject by Tim Urban: https://waitbutwhy.com/2015/03/7-3-billion-people-one-buildi...
Dimensional analysis like this is a weird way to think about a large number of people. It depends a bit on what the average weight of a human, but yeah, that's at least pretty close to true.
https://www.wolframalpha.com/input?i=%28%280.5+miles%29+%5E+...
I usually say if every human being on the planet were placed in Texas, it would be less dense than Paris as an argument against an area being "too crowded", but this is an even more jarring comparison.
Take food production into account and the planet looks a little more crowded.
Nightmare fuel for the next Terminator or Matrix sequel.
And we use one cubic mile of oil every year.