A new computer simulation shows that a technologically advanced civilization, even when using slow ships, can still colonize an entire galaxy in a modest amount of time. The finding presents a possible model for interstellar migration and a sharpened sense of where we might find alien intelligence.
Space, we are told time and time again, is huge, and that’s why we have yet to see signs of extraterrestrial intelligence. For sure, the distances between stars are vast, but it’s important to remember that the universe is also very, very old. In fact, I’d go so far as to say that, in terms of extremes, the Milky Way galaxy is more ancient than it is huge, if that makes sense.
We present a video of a simulation showing the expansion front of a technological species settling a Milky Way-like galaxy, created using the model described in Carroll-Nellenback et al. It illustrates how even very conservative rates of settlement ship launches and ship ranges can quickly lead to a galaxy endemic with technology, and how the rotational and peculiar motions of stars contributes to the expansion. This video confirms and validates previous work showing that the centers of galaxies are promising search directions for SETI.
Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying. – Arthur C. Clarke
“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.” – Calvin, “Calvin and Hobbes”
So that would argue against the presence of any other intelligent life in the galaxy, since we haven’t been colonized by slowboats or Vin Neumann [sorry, typo: I meant Von Diesel] machines. Of course, the assumption is also that civilizations and species last long enough for such major programs to be enacted and that, even if they survive, anyone cares enough to do it.
The authors detailed their assumptions in that paper. I haven’t read it so I don’t know how realistic their assumptions are.
Section 7 of the paper I linked addressed this. They argue that because settlements don’t last that long, all traces would’ve been wiped out:
How long ago could Earth have been (temporarily) visited or settled by such a civilization without leaving any obvious trace? If the settlement occurred 4 billion years ago and lasted for just 10,000 yr would any record of it survive in the geological record?
The answer is: almost certainly not. This implies a temporal horizon over which a settlement might not be seen.
