I'll start. If you removed all the space in the atoms that the human population of the Earth is made up of, all 6.2 billion people would fit in the same space as an apple. Or to put it another way, people (and everything else) are basically 99.99999999%* empty space. When you think of the mass of all the people on the Earth, that's almost unbelievable. * Not sure on the number of 9's, I'd need to know the mass of the human race to be able to calculate it.