According to a new study, calculations indicate that either we are alone in the galaxy, or ET is ignoring us.
"We're either alone, or they're out there and leave us alone," the Discovery News quoted mathematician Thomas Hair, with Florida Gulf Coast University in Fort Myers as saying.
Hair based his estimate of what he believed to be extremely conservative estimates for how long it would take a society to gather the resources and technological know-how to leave its home world and travel to another star.
Even at the comparatively sedate pace of 1 percent of light-speed, the aliens would land at their nearest neighbour star in around 500 years.
"They've either passed us by, or they stay around their home star systems and contemplate their navels," Hair said.
There could be quite a lot of reasons why we are not listed in intergalactic Yelp. Perhaps most important is that we do not have anything that aliens require.
"Any ancient civilization is probably not biological. They don't need a place like Earth. They don't need to come here and steal our water. There's plenty of it out in the outer solar system where the gravity is not so great and they can just take all they want," Hair said.
Or maybe modern-day extraterrestrials are following routes laid out long ago, all of which bypass Earth, he added.