Imagine a person, floating in a space.
It's not a room, cause there are no walls. It's something bigger as you can't see any limits. And there is nothing you can see. Only white light.
He is floating, completely naked, has no objects as bracelets or earrings...
You are speaking to him with a microphone (not relevant) and he hears you, but as there are no speakers, hears you from everywhere. But you can't see him.
How can you tell him what is his right or his left?