Warning:  speculation follows.<p>If we understand correctly, the universe is about 13.7 billion years old.  I recall reading once that there is enough mass (matter plus dark matter) that the Swarzchild Radius of that much mass is approximately 13.7 billion light-years.<p>What if we&#x27;re <i>inside</i> a black hole?  How would that affect how we interpret what we see at large distances?  (For example, does that explain the Hubble redshift?  Does it explain dark energy?)<p>And, if it&#x27;s true, then what is a black hole?  Can you have a black hole inside the Swarzchild radius of another black hole?