I always wondered what’s their energy source? Also when people see them that means photons have had to bounce of them and into the observers eyes. The same goe

I always wondered what’s their energy source? Also when people see them that means photons have had to bounce of them and into the observers eyes. The same goes for the sounds they make, they need to move the air molecules for sound to travel. Or could it be that it all just happens in the observers mind? But that doesn’t account for poltergeists.