mike10 said: "Time Machines and UFO's would have to have things incommon. Due to the great distances. Whats the point of traveling somewhere when there will be nobody to tell about it when you get back home."

Hmmm…not necessarily.  First, you're thinking about it as a human.  As in…assuming that aliens have a life span that is like our own.  This doesn't need to be the case.  In fact, the oldest living tree (actually the root system) has been alive for 9550 years (More about that can be found here ).  So even here on Earth, something living can outlast us by quite a large amount of time.  Nothing to say that aliens, if around, can't do the same.

And to expand upon Nosfer's colonization program…here's a different twist.  Send a craft into space for however long with only robots running things.  The craft gets close to the destination, it begins the "birthing process (like Sea Monkeys!  Pour some in water and watch them grow)."  When adult, run some intelligence program straight into their brains to smarten them up and botta-boom, botta-bing, you've got your shiney and new invasion force without a time machine.

But really, you don't even need to do that.  Just send a small craft with self-replicating robots (nano-technology and beyond) that can use raw materials.  Build, build, build…and once again…you've got your shiney and new invasion force without a time machine.

Can you tell my view on whether or not aliens would be inherently dangerous if they were indeed real and on the way here?