Given the average lifespan of a human on earth today (around 67), and the average population growth rate (somewhere between 1 and 2%), it causes an acceleration in the number of humans living and being born.<p>The notion that this growth is unsustainable is scare mongering. 1.5% growth per year is sustainable indefinitely to colonize the galaxy, if we can just keep the resources needed to support that growth flowing. At some point we will need to create a Dyson sphere around the sun to capture most of its energy, and harvest the raw materials in the asteroid belt between mars and Jupiter. As for living space, it will be superstructures orbiting the sun in the habitable zone.