Slowed down, with a pause between them: two bars, each flashing where it is.
Tricks of motion
Phi phenomenon
What travels from one side to the other?
Nothing: a bar flashes on the left, then on the right. Nothing ever passes through the middle.
Why? Your brain sees motion itself, separately from seeing a thing move. That’s why motion can feel real when nothing moved.
Picture: Drawn by Science Playground · Wikipedia(opens in a new tab)