In reply to Jed Rothwell's message of Thu, 8 Oct 2020 20:53:15 -0400: Hi, [snip] >Robin <mixent...@aussiebroadband.com.au> wrote: > > >> 5) Interstellar gas is not the only problem. A grain of sand or a pebble >> would spell disaster. >> > >You're gonna need a VERY high resolution radar and a laser.
Radar waves are too long for grains of sand. Vaporizing them with a laser will be difficult because it has to happen before the ship arrives at that point, and it's going so fast that a long distance is implied. Also don't even try flying through an interstellar dust cloud. The real point I have been trying to make, is that space simply isn't empty at long distances, so high speeds become very difficult. Without high speeds, travel times are going to be very long. I short, I think we should give up going to the stars physically, at least directly. I suspect that highly advanced civilizations don't actually travel at all, but rather use FTL communications for "virtual" travel. IOW get a distant civilization to send you a movie of their world, rather than actually going there. In such a galaxy, everyone would use similar FTL communications equipment, effectively joined in a galaxy wide "Internet", so the first thing an advanced civilization is going to try to teach one that doesn't have it, is how to build FTL comms gear. Ever wondered what crop circles really are? (AI Robots traveling at low speed can take millennia to travel between the stars, programmed with the ability to reproduce the plans using whatever local "canvas" is available.)
