I fear that the "Great Filter" (http://en.wikipedia.org/wiki/Great_filter http://en.wikipedia.org/wiki/Great_filter) is less likely to be a big rock or hunk of

I fear that the "Great Filter" (http://en.wikipedia.org/wiki/Great_filter http://en.wikipedia.org/wiki/Great_filter) is less likely to be a big rock or hunk of ice whacking planets full of the uninspired, but rather the speed of light necessitating dense civilizations to minimize communication latency. The sooner we expand, the better, because we are only going to become more addicted to information and instantaneous species-wide communication.