Observations show the universe appears flat, yet its true size and global shape beyond the observable horizon may remain forever unknown.

Is the universe infinite? It's one of the most profound questions we can ask, and here's the short answer: We don't know. While we have learned a great deal about the universe, a portion of the cosmos ...

The surface of Earth is finite. We can measure it. If it was expanding, then its size would grow with time. And once again, good ol' Earth helps us understand what the universe might be doing beyond ...