Robert Maxwell wrote:
Von Neuman machines are even less likely considering they would still have to remain fully functional over a truly geologic timescale in order to be in any way functional. If you had technology that robust, it wouldn't need to be self-replicating because it would basically last forever. It's a Crazy Eddie concept that otherwise serves no practical purpose.
It's mundanely obvious that interstellar travel is perfectly feasible for an unmanned probe that can expect to be discovered intact after a billion years or so by an alien race that didn't exist when it was launched. Travel or transport LIVING BEINGS just isn't going to happen, though, without a space fold or something similar. Or -- as Gary mentioned -- if a civilization evolved near the galactic core or in a dense cluster of stars, in which case interstellar travel only takes slightly longer than interplanetary travel.
Still. greater numbers means two things: You still have more machines out there after falling prey to attrition through disaster, wear and tear, etc. Also more machines means covering the distance at sub-light more quickly, spreading like a virus,
But what good does this do us? Okay, so our legacy is an ever-growing set of self-replicating machines, spreading throughout the universe. Cool. What is the practical value, if it's going to take millions of years to amount to anything useful to living humans?
There comes a time when you have to bow to physics...we cant get there fast from here, so it means doing it at sublight, methodically and efficiently. The universe works on cosmic timescales, geological ones, we don't.
Practical value? Well several-fold if you think going into space has ANY practical value. Firstly, it means spreading the human race, if we have any value, then our survival is important to US. Secondly: knowledge, we can gain knowledge through relays, and the network of machines. Thirdly, resources...the machines that are closer to us can provide us with resources as we advance at home and other waves of exploration move outward.
I can look at it in other terms too, if we assume exponential AI...and if that AI has human elements to it, then of course I submit that AI is human and our representative. Its as close to us as any potential alien might get! I--like man scientists and sf writers these days--feel that electronic/digital/machine life is probably going to be our successor, whether you believe in a singularity or not.
If these AI are sufficiently advanced, and if Singulatarians are correct, then we can infuse all matter with intelligence, and this computronium will be our legacy, through the galaxy and beyond. With sublight it just takes longer.