The size of the universe and the distance between everything in it. It takes about 8 minutes for light from our own sun to reach us. And the observable universe is about 5,859,000,000,000,000,000 times larger than that! That is quite a trip. I would need about 293,283,000,000,000,000,000,000,000 charging stops with my electric car to get to the end. I think Iβll pass.
(Someone smarter than me will probably find out that my math is wrong)