First off: why would you assume that we could interact with them? It appears to be phenomenally difficult to get from point to point in the galaxy/universe (se

First off: why would you assume that we could interact with them? It appears to be phenomenally difficult to get from point to point in the galaxy/universe (see the recent trend in science-fiction to stick to a speed of light limited universe). If we come up with some fantastic energy source (see: ZPE), then I'll say that it's phenomenally slow so that no civilization would invest in doing it. If we come up with some civilization that would do so, I'd point out that it's phenomenally slow/difficult to send signals across universal distances. Rational folks think that non-solar-local interactions are probably not possible... Large brained rational folks think to look for solar-local artifacts of Kardashev-scale>1 civilizations (see: http://www.personal.psu.edu/jtw13/blogs/astrowright/2013/03/artifact-seti.html http://www.personal.psu.edu/jtw13/blogs/astrowright/2013/03/...). Recall that early explorers met Native Americans and called them Indians because they had misinterpreted distances, didn't know all of the continents, etc. We have a history of overcoming increasingly large distances with improved transport. This does not mean that we shall always do so. It may be depressing, but it may be the case that exponential curves in natural do not exist. We may live in a time where we understand that sigmoids rule the evolution of our world/civilizations... (And no the plural of Malthus is not proof of an exponential curves in nature...)