I was raised godless. Churchless. Creedless. Without spirituality except for one thing. Once a week, on Sunday nights, we made a big bowl of popcorn, flavored with Lowrey’s seasoning salt, and gathered on the couch to watch Carl Sagan’s groundbreaking and breathtaking science for the masses series, “Cosmos.” The show is back for a new season, and the first episode has a special guest who’s an old friend.