Quote - ...I think that we're pretty safe.  Unless FTL or forms of ultra-space traversal are possible - despite what all of the SciFi genre promotes heavily - there is little chance of any two sentient species from different planets meeting unless the planets reside in the same solar system.  My calculations of the time required just to jump from one galaxy to the next at light-speed is in the millions of years (!).  That pretty much rules out extra-galactic invasion without FTL travel.  Heck, the travel time to the nearest star at light-speed is something like 4 years (at more realistically possible speeds it may take 20 to 40 years)....

 

You're ruling out very long lived species who may be able to withstand high acceleration and/or boredom for long periods.  Maintaining a 4 G thrust for a while will get you to an respectable fraction of the speed of light and time dilation will start to have an appreciable effect on anything inside the craft.  There's also no reason to believe that 100 or so years is the upper limit of lifespan for an intelligent being.

There's also the idea of generation ships, which may travel slowly but contain an entire biosphere.  The original travellers may not be alive when they get here but their descendents would be.  

There are also some ideas which suggest intelligent life evolved a lot earlier, closer to the galactic core.  We're stuck out here, a day late and a dollar short. 

In any case, assuming we do receive contact from another species, there's still the matter of the "Outside Context Problem".   That is, contact with something or someone far in advance of the tribe.   Human history is littered with these, and so far, no contactee has ever come through it unchanged.  And it's usually for the worse.  

And while I have your attention, I'm selling a nice new line in very stylish tinfoil hats. :biggrin:

Coppula eam se non posit acceptera jocularum.

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