[Anonymouse]

Oh, please. For Obama - or anyone else - to issue such a denial means less than nothing. Even if they were here, how would we know? This is a big planet which has still not been explored in its entirety, and there are vast tracts of unoccupied land in the States alone. If they exist, they could be here; if they arrived long enough ago, there would've been no radar, satellites etc. to detect their arrival.

Fact: we know nothing about conditions in other solar systems, other than by inference. To the best of my knowledge, no other Sol-type star has been observed to have planets; all the extrasolar planets whose existence is confirmed or inferred seem to be Jupiter-types in orbit around red dwarfs or red giants. Then again, we can't rule out life even on (in?) those planets, as Arthur C. Clarke suggested in 2010: Odyssey Two.

It's pointless to issue such denials when there is no credible evidence whatsoever one way or the other.

Admittedly, the very fact of our existence is the consequence of a series of unlikely accidents and coincidences:

The stellar remnant left after a star's supernova several billion years ago just happened to create the life-friendly mix of elements we observe in our solar system;

There was just enough material to form a life-friendly G2 star, as opposed to a white or blue giant;

Earth just happened to form at just the right distance - not too far away, not too near;

It was hit a glancing blow by another, Mars-sized protoplanet during its formation, which resulted in the creation of the Moon, thus helping to stabilise the planet's wobble and axial tilt, without which conditions would have been too unstable and shifting for life to get a hold;

The Moon's gravity caused a fairly even distribution of radioactive isotopes throughout the crust (which is relatively thin owing to that same gravity), resulting in 1) a background count high enough to promote mutation but low enough to not kill everything off, and 2) a degree of tectonic activity sufficient to shake things up with volcanic eruptions every so often, but not enough to wipe out life altogether;

It just happened to get hit by multiple comets, bringing water;

Jupiter just happened to form at the correct distance and with the correct mass and gravitational influence to become an interplanetary Hoover, deflecting enough asteroids, comets and the like to ensure Earth didn't get too battered during and after its formation.

All of it very, very unlikely. Nevertheless, we are here. If it could happen here, by the principle of universal mediocrity, it could well have happened elsewhere and most likely did. And if anyone mentions the Fermi Paradox (a misnomer; it's not a paradox at all), I shall bop them firmly upon the head. There are any number of reasons as to why we haven't heard anything from other civilisations. Hell, we might well have received such a signal already and simply not recognised it for what it was. We still don't know what the Wow! Signal was.

Hence the US government's position on the matter is utter nonsense. They don't know. No-one does.