Video: Here's a thought exercise that starts getting kind of gross the deeper you dive into it: What if the entire world's population lived in one city? What would that city look like? How big would the city be? Or how small can you pack it? Is it even possible? RealLifeLore says that you can fit 7.4 billion people into a city as big as Palestine. Which is, like, basically a bit bigger than Brisbane. Yeah, the entire world in that teeny tiny place. How did the maths get figured out? By using real world calculations. In Hong Kong, there used to be a place called Kowloon Walled City, which was the most densely populated place on Earth. If you stretched the population inside that area to a full square kilometre, there would be 1.2 million people inside. Using that as the gauge for this preposterous question lets you fit the entire world population inside Palestine.
The rest of the video takes a look at other densely populated places on Earth like Singapore, Manila, New York City, Dharavi Slum in Mumbai and so on, and uses their population density to see what size the city would be with the world's population inside. It's weirdly interesting stuff.