The Illusion That Makes You Question Reality (2)
might explain one of the oldest illusions on Earth.
I'm sure we've all experienced that incredible feeling
that you get when you go out, look up at the night sky,
and you see shapes emerge from the stars, constellations.
Different cultures have connected the sky dots
slightly differently over the past few thousand years,
but one that always seems to be seen the same is this.
The rough shape of a human wearing a belt.
We call that one Orion.
Incidentally that reminds me of a joke:
Ever look up at the night sky and see Orion's belt?
Big waist of space if you ask me. (chuckles)
It's like a belt around the waist.
(insects chirping)
Ah, whatever, that joke only has three stars.
(crowd boos)
Anyway, this is probably going to ruin your horoscope,
but the shapes we see in the stars
they happen for the same reason we see a chair
in a bunch of random strings.
Because we happen to be viewing it
from a very specific point of view.
If you were somewhere else in space, the stars of Orion
(board scratching)
would look like this.
They're all different distances from Earth,
and well, nothing special
to our friends on Alpha Centauri or whatever.
It's only because you happen to be right here
that this group of stars means anything at all.
(board scratching)
Most of the illusions in this video
were invented by a guy named Adelbert Ames.
You don't meet a lot of Adelberts, do you?
Around 1910, Ames was studying to be a lawyer,
and decided he wanted to be an artist instead.
It was always a fun conversation to have with mom and dad.
When he started studying how the eye senses the world
with the goal of making more realistic-feeling art.
But Adelbert ended up abandoning art,
and spending the rest of his life
designing a series of elaborate demonstrations
to try and unlock the secrets of how we see the world.
Those demonstrations have captivated scientists
and the public ever since.
Just before Ames died, the plans for these demonstrations
were published in a book that is incredibly hard to find.
But thankfully I was able to find a copy,
thanks to something amazing called the library,
which is like the internet if it was a building
that you had to go to.
And one of the strange things about most of Ames' illusions,
is most of them only work when viewed with one eye,
from a very specific spot.
Which is why so many of them work so well in video,
because the camera is essentially like viewing the world
with one eye.
And as powerful as these illusions are,
if you were to view most of them with two eyes,
or if you were able to move around a bit,
they wouldn't work.
So even though they show us a ton
about how our visual system can kinda break down,
they also kind of show us how awesome our visual system
really is when it does get all the information it needs,
from both of your eyes!
Unfortunately, you still only get to use one eye
for the rest of the video, the camera
but there's one last set of visual cues
that I have to tell you about,
for size and how far away things are,
and they only work because you have binocular vision.
Okay, try this: Hold up two pencils or pens,
one in front of the other.
When you focus on the rear object,
you see a double image of the front object,
one on each side.
Close one eye at a time,
and you'll see that your right eye sees the left image,
and your left eye sees the right image.
Now, focus on the closer one.
And suddenly the back one is doubled.
Now your right eye sees the right image,
and your left eye sees the left image.
So what's going on?
When we look at a fixed point, your eyes move individually,
so that point hits the center of each eye.
The closer an object is to you, the more extreme the effect
but your brain is sort of always unconsciously comparing
how different the picture from each of your eyes is.
And it uses that as a clue for how far away things are.
When an object is really close to your eyes
you can actually sense the feeling of your eyes
crossing inward, to focus on it.
You can even feel how the muscles that focus your eyes lens
are flexing and pulling to bring something into focus
and get another clue that way.
There's clues like texture.
You can see more detail on closer things
than you can far ones.
And clues like parallax
which is how objects at different distances
move differently relative to you.
You actually have a ton of clues at your disposal
to judge what you see.
So we build our picture of reality
from these bits and pieces from clues.
Not the full picture.
The software of your brain.
If you wanna think of it that way
it looks for certain clues that it thinks are important.
And your reality is always built
from that incomplete information.
Most of the time that incomplete information
is still good enough
to build a an accurate model of reality.
But the Ames illusions show us that sometimes
incomplete information isn't enough.
There's this idea that in some ways, especially today
if different people are given the same information
then we can end up with a very different picture
of what is real and true.
But these illusions show us the opposite really
that when it comes to seeing at least
evolution has made it so that very different people
perceive the world in the same way.
And that's kind of nice to hear these days.
Stay curious.
Thank you to Policygenius for reporting PBS.
Policygenius is an insurance marketplace,
not an insurance company.
Policygenius combines that marketplace experience
with online tools, an educational library
on all sorts of insurance topics
and guidance from humans to get you covered.
For example, if you're searching for life insurance
Policygenius offers info and quotes
from most insurance companies all at once.
You can get personalized quotes, apply online,
and compare your quotes all in one place.
Additionally, Policygenius offers advice
from people who work in the industry.
Their team handles the paperwork, scheduling,
and negotiating with the insurance company on your behalf
as part of the service.
For more information,
click the link in the description below.
I wanna say a big thank you to Brian from Real Engineering
for 3d printing, this nifty, little thing.
There's a link to his channel down in the description.
And as always a huge thank you
to everyone who supports the show on Patreon.
Patreon, you know how it works.
It's how you can follow the channel
and support video like this without any AI,
any algorithms in the way.
Just you and me hanging out, talking science.
If you wanna learn how you can support the channel
there's a link down in the description.
Thank you very much.
I will see you in the next video.
- First years, I'll fight you Voldemort, I'm grown up now.
