Who hasn't looked into the sky and wondered if there's life out there, somewhere, looking back at us? Is it possible there's alien life closer to home — within the bounds of our solar system? The ...

I watch Rufus, a friend’s dog, chew enthusiastically on a rubber bone. I know the dog is alive, and his toy is not. I know that intuitively. But can I prove it scientifically? Can science parse the ...