Oh! Good question! You would think it would be something like galaxies, black holes, or the big bang. But for me the most fascinating thing in the entire universe is the life we have right here on Earth. So far its the only place we know of that has life. And, life is pretty special, unlike the things above – galaxies and blackholes for example – life is not predicted by the laws of physics. It is not to say that it doesn’t obey the same laws of physics, but there is no equation you could write down that would predict life should exist. So why are we here? Such a cool question to ponder. I think we are pretty special and that fascinates me.