Good question

I went for a walk with Papa today, and while we were on the road between villages a man came past us on a bicycle, travelling pretty fast.

Papa said, "Did you see that bike? I think it was electric. See how slow he's pedaling, but how fast he's going? Notice how quiet it is? That's why I always tell you that you have to look both ways when you cross the street, because in the future there will be more and more electric cars and they will be quiet like that bike, the only noise they'll make is the sound of the tires on the pavement, and that's pretty quiet. So you can't just listen for cars, you have to look, too."

I thought about it for a long minute, then I asked, "Papa? How do you know the future?"

Papa just started laughing, and he laughed for a long time.