Population reduction isn't necessary for wilderness (was Space habitats)

--- In spacesettlers@yahoogroups.com, "sailor.barsoom" wrote:
> In something set three hundred years from, I have the population of Earth being less than a billion, several millions of them living live of deliberate primitiveness. People wanting to be noble savages or such. Except for the "savages," most people on Earth live in clean cities with aggressive recycling and energy from space. There are also about a billion tourists on Earth at any given time.
> Most of the planet is set aside as wilderness areas and historical parks, with exacting restrictions on how many people can visit at any one time and what they can do.
> The population of the Solar System is forty billion.
> How much of this is realistic?

Energy from space (to Earth) isn't realistic, given the presence of cheaper alternatives. A population of less than a billion is realistic, but not necessary. Most of the planet could be set aside as a nature preserve even with an Earth population of a trillion.

Also realistic would be 100 trillion on Earth, and another 100 trillion on Venus. To achieve this in only 300 years might require aggressive pronatalist policies, but it's doable. A compounding APR of 3.4% would do it (implying 28x growth per century). To make the planets more habitable for 100 trillion people on each, solar kites/shields/generators could be flown below each planet's Sun-planet L1 point. Venus's shield/generator could also power factories producing food and other proteins for export to Earth. This would leverage Venus's greater natural-abundance of nitrogen.