Quote Originally Posted by a500lbgorilla
It took our planet half it's life for us to pop up. It's taken us 2 million years to develop the means to send probes to the outer reaches of our solar system. It's hard for me to imagine that another planet some where has lasted long enough to develop the lifeforms capable of traveling distances of light years and to do it in a manner which we can't sense.
The sum total of technology we've developed so far has happened in an eyeblink relative to our time on Earth as a distinct species. It's not unfathomable that we could develop the technology to traverse interstellar distances within the next few hundred years.

It is theoretically possible:

http://en.wikipedia.org/wiki/Wormhol...able_wormholes

Assuming the laws of physics are universal, other intelligent species - that I, for one, believe do exist throughout the universe - will eventually arrive at the same conclusions and strive to solve the problem. I don't think it's unreasonable to presume that some have beat us to it.