Finding alien life wouldn't be terrifying. It would be a profound relief.As Professor Brian Cox explains, the thought that keeps him awake at night is the possibility that complex life is so incredibly rare that Earth might be the only inhabited planet in the entire Milky Way galaxy.If we are truly alone, it means that if humanity destroys our world, we aren't just ending our own story. We could be permanently extinguishing all intelligence and meaning in a galaxy of 400 billion stars; a terrify