Helpy, would you please explain something to me. I saw this chart of the Universe and it had this really, really, really big circle described as the known universe. Outside this circle was the description, “unknown universe”. My question is, if it is unknown, how did they know about it?

Gossip! As you are doubtless aware, modern cosmological research is pretty much all about salacious rumors. For instance, consider all the speculation about how “large” Pluto is, and whether or not it is really a “planet”.  Similarly, cosmologists spend an amazing amount of time debating how hot Venus is, and whether Jupiter is nothing but hot air. As to the unknown universe, it’s not so obvious that the gossip is ill-founded.  Who knows what sorts of things they get up to over there?  No one does!  Certainly we’ve heard nothing of them maintaining high standards of decency, though.

Still, it is mostly gossip, and it is important to remember that sometimes, things cosmologists say turn out to have been largely a result of someone’s agent trying to stage a publicity stunt.  Of all the sciences, cosmology has the highest proportion of research budgets allocated to defending libel suits, higher even than geology.