no but seriously I still get chills thinking about turning off my headlamp in the cave and The Hand That I Did Not Actually See, and it’s been twelve years since it happened

it’s such an unreal experience


you turn off your light in a cave and wave your hand in front of your face


you can see this shadowy thing moving in the black space where your hand is

it looks like the same shadowy thing you would see in your room at night if you waved your hand in front of your face, it’s there and vaguely hand-shaped, and your brain recognizes it as your hand because your brain is aware of where your hand is and what it is doing

But You Are Not Seeing Anything

Inside a cave, there is No Light. No matter how far your pupils spread, there is no light for them to draw in, no light to put an image on your retina.

But your brain just Fucking Assumes that because it knows where your hand is and what it is doing, clearly it can see it.

So it creates a shadowy thing for your eyes to be seeing.

Brain is like “there’s a hand there”

Eyes are like “yup sure thing brain I can totally see it”

Brain is like “nice”

but there is no hand, you cannot see the hand, you are seeing a literal actual hallucination in the cave because your brain thinks it knows best

Caves are awesome, but also terrifying. Thank you for coming to my TED Talk.

we once went spelunking, and a our guide said that once he was in a cave with a stream, so he could hear running water, and his brain was like ‘oh, running water? that means there must be Ducks out there’. and he saw like…low light shadows of ducks. that his brain just Put There.