Hey, Vsauce!
Michael here.
I am distorted.
The pixels you are watching have been time displaced.
They've been mapped onto a gradient
and the darker the region they're mapped to,
the further behind they lag.
The effect is really fun, but it's certainly not realistic...
Or is it?
Many, many popular digital cameras suffer from lag-induced distortion,
like what you just saw, though much, much more subtle.
Usually completely unnoticeable. It's called a rolling shutter.
Instead of snapping a full exposure at once,
they quickly scan strips of each frame.
It's usually undetectable, but when the subject changes
faster than the camera scans, you get the faintest jello-y,
wobbly rolling shutter effect. Really fast things,
like vibrating guitar strings and airplane propellers
are famous victims, but people can be too.
Luke Mandel submitted this photo to Boing Boing.
His camera scans left to right and, in this instance,
managed to capture a blink, eyes closed, when the scan
began and then opened in the reflection,
scanned a fraction of a second later.
But the rolling shutter effect is not just a neat curiosity.
It represents a fundamental and inescapable distortion
that affects everything we see, rolling shutter or not.
First things first, let's talk about distortions.
A hallucination is a distortion of reality
when there is no apparent stimulus.
If you are merely misinterpreting an actual stimulus,
that is an illusion. But some distortions occur
before our sense organs and minds get in the way.
They are called optical phenomena.
They are not the result of sensation or perception gone wrong.
Instead, optical phenomena are distortions caused
by the mere properties of light and matter in and of themselves.
If you look up at the sky and see a giant, vivid drinking gourd,
you are hallucinating. But if you see a flat, two-dimensional,
connect-the-dots Big Dipper, you are seeing an illusion.
It's an illusion because those dots merely appear
to be on the same plane, like holes poked in the dark roof of the sky.
In reality, those dots are stars, light years apart
from one another in three dimensions.
As Celestia's brilliant, free, real-time, 3D visualization
of space shows, from different perspectives, besides our own,
they look a lot less like a dipper or plow.
In fact, all constellations and asterisms are geocentric illusions.
From a wider perspective, their outlines point inward to the single,
lowly point in space that gave them their names. But you can't blame us!
I mean, Earth is the only perspective any human has ever had.
And even Voyager One, the most distant man-made object,
is still not even close to being far enough away
for the constellations to look even
remotely different than they do here on Earth.
It's also not our fault, our eyes and brains fault,
that distant, distant stars weren't included
in our early cosmic connect-the-dot game.
Sure, our eyesight could be better,
but optical phenomena are also to blame.
If it weren't for redshifting and the Inverse-square Law
and light extinction, distant things could be seen in all their glory.
The night sky would look phenomenal. Many structures up there are huge.
They're just too dim for their hugeness to be appreciated.
When we see Hubble telescope images of distance objects
like the Helix Nebula, it's easy to think that without
a telescope to zoom in, the object must
just be a tiny point in the sky. But, in reality,
even though the Helix Nebula is 700 light years away,
it's three light years across.
If we could make the Helix Nebula less dim,
if our eyes could take a really long exposure of it,
we would see the Helix Nebula as it really is,
nearly 70% the apparent diameter of our moon.
This is a serious picture.
That is how large the Helix Nebula would appear in the night sky
from Earth if it just wasn't so dim.
Our moon is tiny in the sky, by the way.
It's easy to think of the moon as this huge, baseball sized thing
up there in the sky, but that's an illusion.
Try this the next time you see the moon.
Grab a sheet of notebook paper and you will notice
the angular diameter of the moon is the same size
as a hole punched in a sheet of notebook paper,
held an arms length away. Seriously, try it sometime.
It shows just how cute and tiny our little moon is.
The Orion Nebula would appear even larger if we saw all of its light.
And the Andromeda Galaxy--just a smudge in the sky to our eyes--
but if our eyes were better at collecting dim light,
we would see Andromeda's true extent in our sky.
Of course, our night sky doesn't look like that.
Distant objects are dimmer.
That's a bummer.
But light still wins when it comes to speed.
Light travels at the fastest speed, in fact.
In a vacuum, light travels 300,000 kilometers a second.
That's fast.
But not really.
I mean, not compared to how far apart things are in the universe.
Sydney, Australia, is 1/14th of a light second
away from London.
But the Andromeda galaxy is two and half million
light years away from London. To put that in perspective,
let's take a light speed journey from London to Sydney.
It would look like this. Ready? Three, two, one...go!
Nice. Alright, alright. Here's the Andromeda galaxy, okay?
Now, relativistic effects aside, let's take a look at
what it would look like to travel toward
the Andromeda galaxy at the speed of light.
Are you ready? Alright. Three...two...one...go!
(sighs in annoyance)
Yeah. I mean, seriously, it's pretty lame.
Even at the speed of light, the fastest speed possible,
a year from now, we won't even be a millionth of the way there.
That's how far away Andromeda is.
It's almost sad in a way.
But this brings us back to the rolling shutter effect.
The Andromeda galaxy is huge.
It's more than a hundred thousand light years across
and our view of it is tilted, which means that on the plane
we view it in, light from the back represents
what Andromeda looked like thousands and thousands of years
before what light from the front represents.
Changes in its appearance reach us sooner from the front
than from the back. Andromeda is rotating,
spinning at hundreds of kilometers per second in some places.
Now, a lag between light coming from near and far points
on a spinning object results in a skewed image.
The rolling shutter effect on a cosmic scale applied, to say,
a Chess board, seeing the front ahead
of the back is pretty trippy and dramatic.
So does that mean we see wobbly, funhouse mirror,
rolling shutter effect versions of Andromeda
and other distant galaxies? Well, technically, yeah.
But the distortion is negligible.
It may as well be ignored. Why?
Well, the speeds used in these visualizations are not to scale.
On average, yes, matter within galaxies orbits the galactic center at hundreds
of kilometers per second, but galaxies are so huge,
it takes them hundreds of millions of years
to complete just one rotation. In other words,
the lag between light reaching you from near and far points
on a galaxy is nothing compared to how much time it takes
matter in the galaxy to travel that same distance.
In the case of Andromeda, if you insisted on seeing
Andromeda as it really is, that is, corrected for any lag
caused by the fact that the speed of light is finite,
the most extreme points on the galaxy would only need
to be adjusted by about a ten-thousandth of the width of any image.
In this case, less than a pixel.
So it's not a big deal.
But it's not a nothing deal. It's real.
In fact, everything we look at is, in some way,
distorted by the fact that the speed of light is finite.
Your own feet are about five to six light nanoseconds
away from your eyes,
which means, when you look at your feet, you're seeing where they were,
5-6 nanoseconds ago,
5-6 nanoseconds in the past.
Of course, a delay that brief is pretty much undetectable,
but it is calculatable. If it makes you feel a little sad to know that,
even with the sharpest mind or the best instruments,
appearances still depend on where you are,
that optical phenomena ensure appearances are always relative...
don't feel bad. We call the people closest to us our relatives.
We're really just a family.
A big family of reference frames that, like a family,
don't always agree, but do have plenty of cool things to look at.
I'd like to think my editor, Guy, for help with
the rolling shutter effect in this video.
And I'd like to thank you because, as always,
thanks for watching.
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