I think the large distances between solar systems render the question of their existence irrelevant, only by our advancements in propulsion and physics does the question hold any weight.<br><br>Simulations have been done that show that with multigenerational ships you could colonize most of the galaxy in 90 milion years. Yet space seems empty of life. <br><br>We are either the first or other aliens have failed to colonize or have seen the expenses of resources as being too great to warrant it.,(reply>), 1) We’ve sampled an infinitesimal part of space, equivalent to taking a gallon of water, not finding any multicellular life &amp; then declaring our oceans to be devoid of life. 2) The tools we’ve used are equivalent to trying to find cells &amp; viruses using a magnifying glass or trying to find Kuiper Belt Objects using a backyard telescope. &amp;, 3) When we have found things that looked like “techno-signatures”, we’ve used even nearly impossible explanations to explain away what we’re observing.