India, Oct. 10 -- There's a space-age joke about a man who has lost the keys to his car. He keeps looking beneath the nearest lamppost.

Asked why, he replies: "It's where the light is."

For millennia, we have gazed up at the stars, haunted by the question: Are we alone? Our means of answering that question have remained frustratingly limited.

To extend the metaphor of the joke, we've been looking where the light is; where we are.

Unlike in the joke, though, we aren't even sure the keys exist. (Though we're reasonably sure they should.) We don't know where the street leads, what's in the next district, or indeed how we got to the lamppost to begin with.

It's a muddle.

Are we now set to take the leap that could help us un-muddle it? ...