Can everyone in the world fit in a 1km x 1km x 1km cube?

Yes, everyone in the world could theoretically fit into a 1 km x 1 km x 1 km cube. With a global population of about 8 billion people, each person would occupy approximately 0.125 cubic meters if distributed evenly. This volume is feasible given the total volume of the cube, which is 1 billion cubic meters, far exceeding the space needed for the population.