He found that even if the alien ships could hurtle through space at a tenth of the speed of light, or 30,000km a second, - Nasa's current Cassini mission to Saturn is plodding along at 32km a second - it would take 10bn years, roughly half the age of the universe, to explore just 4% of the galaxy. His study is reported in New Scientist today.
All this really shows is that the galaxy is immensely huge. That's nothing new and can be derived practically from just looking at the stars in my humble opinion.
It doesn't really say anything useful about whether it might be crawling with life or almost empty with our planet being literally the only one with life. It only says it might be likely that even though a civilization tries to search for life, it may not ever find it because of the huge size of the galaxy.
Studies that search for planets with similar conditions are much more valuable in my opinion, contrary to these statistics-based fantasies.
Why? Well first of all, because planet-colonizing and or discovering alien races (that might have the ability to visit earth if they knew where we are) implies a civilization that's highly intelligent AND technologically way more advanced than we are.
There's no logical reason to assume that no alien race could ever figure out how to "fly" at speeds of 30.000km per second or far higher. There are multiple (albeit extremely sci-fi compared to our own technology) solutions... worm-hole travel, achieving near-light speed and what not more.
So, distances to overcome may be huge in our galaxy, but if we assume there are aliens as intelligent or even much more intelligent than we are... why not assume that their technology might be much more advanced as well? It only makes sense that IF some of the UFOs spotted here on earth are indeed of extra-terrestrial origin, that their technology is more than capable of dealing with the problems of interstellar travel, light speed-limits and what not more.
Basically all this theoretical talk is pointless anyway as there's no way to check any of these theories (yet), but it's crazy how some people think similar kind of rules would HAVE to apply to alien civilizations as would apply to us, not realizing those aliens might have figured out things we have not.
Don't forget that our higher-level technology is only something of say the last 200 years or so, with the more important stuff going on the last 80 years or so. Now just imagine a alien civilization that has been technologically capable to invent and discover things ten or hundred times longer than we are. Suddenly our greatest inventions might not be so great compared to the knowledge those aliens may have.
Again, though.. it's all theoretical.
