According to UN statistical data and projections world population will begin to decrease by the middle of this century. This paper uses rate equations (fully analogous to those employed in condensed matter physics) to simulate the time evolution of world population, making use of UN population...

An article in Science (4 November 1960) proposed Friday 13 November AD 2026 as the "Doomsday" of planet Earth, a doomsday produced by the "world population" going to infinity. In that paper, a rudimentary rate equation describing the evolution of the world population with time, was approximated...

The UN data (1950-2010) and projections (both medium and low-fertility variants for 2015-2040) show that fertility rates are already below replacement level in all continents except Africa. In this paper we develop a simple new approach for population projections based on a Improved Rate...