Hey Vsauce I'm Jake and in the Chronicles of Riddick series, one of Riddick's unique
features is his ability to see in the dark. Of course, this is due to a fictional operation
called a shine job that creates something similar to what a lot of animals are born
with, a tapetum lucidum.
The tapetum is a reflective membrane in the animal's eye, behind the retina, that acts
as a mirror, re-sending the photons back out for another chance to be collected. If you've
ever taken a photo of your dog or cat with a flash on, the glowing eye effect is the
light being bounced back from the tapetum. It is also what fueled the old tales of glowing
eyes in the dark.
Unfortunately we don't have shine jobs or tapetums to give us enhanced night vision,
but when it's dark, when all the lights are off, there are still things that we see...or
are there? What exactly do we see in the dark?
Our retinas, the layer of cells in the back of our eyes have two main light receptors,
the rods and cones. Each eye has about 6.5 million cones, they allow us to see colors
and shapes but require a lot of light. They are also mainly located in the Fovea, the
most sensitive part of the retina and the area with the highest density of cones.
The further we get away from the center of our retina, the more Rods we find and the
less cones there are. Rods are incredibly light sensitive but they are also color blind.
You can test this by taking something with color and holding it out so its in your peripheral
vision, you'll be able to see it but you won't be able to tell what color it is.
When we are in the dark, we use our rods to see, but it isn't immediate. It takes at least
30 minutes for our eyes to fully adjust. That's why when you go from a room with light to
one without, it feels completely dark, completely alone.
It's speculated that the eyepatch that pirates wore was for when they would go below deck,
where there wasn't much light, they'd have one eye that was already adapted to the dark.
Cutting out the time needed to wait.
But if you do wait, if you do just sit in the dark you might start to see things, things
that aren't really there...phosphenes. When you close your eyes or lay in bed at night,
you sometimes see strange patterns or soft white lights. You
can actually experience it right now by closing your eyes tightly and *gently* pressing on
the center of your eyeballs with your index and middle finger.
This phenomenon is also referred to as the Prisoner's Cinema, and has been reported by
astronauts, pilots and of course prisoners after spending prolonged amounts of time in
complete darkness. With the Prisoner's Cinema though, people start to see colors shifting
and dancing and, occasionally, forming human shapes.
But what can we truly see in the dark? Well that depends on where you're looking. In a
room with hardly any illumination you are completely blind in the center of your retina,
where the fovea is. Since it is entirely cones, there is nothing for them to pick up.
Averted Vision. It's a technique astronomers do, where they see using their peripheral
vision. Next time you're in your room in the dark, take a piece of white paper and stare
directly at it. You probably won't see it even though it is right in front of you, but
if you avert your eyes to one side a bit, you'll suddenly be able to.
We might not have shine jobs or tapetums to give us more light, but what we do have are
our minds. They show us things even when we can't see, they remind us that we aren't alone.
We just need to keep looking...even if it is in the dark. And as always, thanks for
watching.