AP Photo

If you would like to get an idea of how fast the reach of humankind is accelerating, consider this. In 1783, only 230 years ago, the Montgolfier brothers gave a public demonstration of the world’s first practical antigravity device, the hot-air balloon. It reached an altitude of about one mile. And 160 years later, a V-2 rocket, sent straight up, reached 128 miles.