With the help of these tools, scientists have pieced together a lot of knowledge about space. But what do we really know about the universe, and how do we know it? Where did the universe come from? Where is it going? Did the universe have a beginning, and if so, what happened before then? What is the nature of time? Will it ever come to an end? Can we go backward in time? Recent breakthroughs in physics, made possible in part by new technology, suggest answers to some of these longstanding questions. Someday these answers may seem as obvious to us as the earth orbiting the sun-or perhaps as ridiculous as a tower of turtles. Only time (whatever that may be) will tell.