I told V that if he got any skinnier he'd slip through the fabric of our universe and in to another dimension. He called me a liar. I then launched into a lecture, and when I reached the fourth dimension, I said, "And if we ever want to travel to other galaxies personally, we'll have to figure out how to move through space without the normal correlation of time--" "Mommy, how on earth does THAT work?" And you know . . . I had no idea.
Note to self: brush up on science.