I was visiting him for lunch in Maui today, and I asked him exactly how it is that he does the time-travelling thing.
Uncle explained that it was by animism. Just as every natural formation, animal and plant had a guiding spirit, so does every abstract concept. They become unhappy when they are not appeased, but they can be generous when given proper devotions. So he built a shrine to the idea of time-travelling. He made it out of a clock he got from Grenwich, rewired to run backwards, and included several hairs from the heads of H.G. Wells, Keanu Reeves and Michael J. Fox, and then put some neutrinos on top of the whole thing. The living force of time travel was pleased, and he became able to do the trick.
He suggested that I do the same thing, but I explained that I'm not an animist. He said that was okay; all I'd have to do was make a shrine to the concept of animism, and it would appease animism's animus.
I was happy with the idea, so I scratched Uncle's ears, gave him a snack, and said, "Good boy! Who's a good boy? Yes, you are!" Uncle loves it when people do that.
Then I had to catch my flight back - I was only in Maui for an hour and a half for lunch. Ont he flight, I had a better idea.
I spent the rest of the day assembling a shrine to the concept opposite of animism - the idea that no object has an inhabiting spirit. It took me a while, but it's all made.
When I began offering my appeasance, I had a stunning revelation - dogs can talk!