The American Association for the Advancement of Science sounds like a feet-on-the-ground organization. But in a recent meeting in Boston some scientists took flight, at least in imagination. They talked about physically possible step-ups in the speed of travel that might make it conceivable to reach a near star. Alpha Centauri, our neighbor, is 4.4 light-years from the sun, which means 6 trillion miles times 4.4. We learn that if a cave man 11,000 years ago had launched something at the pace of Voyager, it now would be only one-fifth of its way to the nearest star.
The scientists, joined by some writers of science fiction, speculated. With foreseeable developments, they envisioned a crew that could reach Alpha Centauri in 50 years. For even longer voyages, genetic diversity in the crew would be a problem. You’d need a large bunch of people and careful planning.