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Hey, Vsauce!

2
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Michael here.

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I am distorted.

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The pixels you are watching 
have been time displaced.

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They've been mapped onto a gradient

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and the darker the region they're mapped to,

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the further behind they lag.

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The effect is really fun, but 
it's certainly not realistic...

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Or is it?

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Many, many popular digital cameras
suffer from lag-induced distortion,

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like what you just saw, though 
much, much more subtle.

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Usually completely unnoticeable.
It's called a rolling shutter.

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Instead of snapping a full exposure at once,

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they quickly scan strips of each frame.

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It's usually undetectable, but 
when the subject changes

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faster than the camera scans, 
you get the faintest jello-y,

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wobbly rolling shutter effect. Really fast things,

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like vibrating guitar strings
and airplane propellers

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are famous victims, but people can be too.

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Luke Mandel submitted
this photo to Boing Boing.

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His camera scans left to
right and, in this instance,

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managed to capture a blink, 
eyes closed, when the scan

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began and then opened in the reflection,

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scanned a fraction of a second later.

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But the rolling shutter effect
is not just a neat curiosity.

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It represents a fundamental
and inescapable distortion

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that affects everything we see, 
rolling shutter or not.

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First things first, let's talk about distortions.

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A hallucination is a distortion of reality

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when there is no apparent stimulus.

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If you are merely misinterpreting an actual stimulus,

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that is an illusion. But some distortions occur

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before our sense organs and minds get in the way.

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They are called optical phenomena.

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They are not the result of sensation 
or perception gone wrong.

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Instead, optical phenomena
are distortions caused

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by the mere properties of light 
and matter in and of themselves.

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If you look up at the sky and see 
a giant, vivid drinking gourd,

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you are hallucinating. But if you
see a flat, two-dimensional,

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connect-the-dots Big Dipper, 
you are seeing an illusion.

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It's an illusion because those dots merely appear

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to be on the same plane, like holes 
poked in the dark roof of the sky.

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In reality, those dots are stars, light years apart

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from one another in three dimensions.

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As Celestia's brilliant, free, 
real-time, 3D visualization

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of space shows, from different 
perspectives, besides our own,

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they look a lot less like a dipper or plow.

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In fact, all constellations and asterisms
are geocentric illusions.

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From a wider perspective, their outlines 
point inward to the single,

50
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lowly point in space that gave them 
their names. But you can't blame us!

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I mean, Earth is the only perspective 
any human has ever had.

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And even Voyager One, the most
distant man-made object,

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is still not even close to
being far enough away

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for the constellations to look even

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remotely different than they do here on Earth.

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It's also not our fault, our eyes and brains fault,

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that distant, distant stars weren't included

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in our early cosmic connect-the-dot game.

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Sure, our eyesight could be better,

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but optical phenomena are also to blame.

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If it weren't for redshifting
and the Inverse-square Law

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and light extinction, distant things 
could be seen in all their glory.

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The night sky would look phenomenal. 
Many structures up there are huge.

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They're just too dim for their 
hugeness to be appreciated.

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When we see Hubble telescope
images of distance objects

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like the Helix Nebula, it's easy to think that without

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a telescope to zoom in, the object must

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just be a tiny point in the sky. But, in reality,

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even though the Helix Nebula
is 700 light years away,

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it's three light years across.

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If we could make the Helix Nebula less dim,

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if our eyes could take
a really long exposure of it,

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we would see the Helix Nebula as it really is,

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nearly 70% the apparent diameter of our moon.

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This is a serious picture.

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That is how large the Helix Nebula 
would appear in the night sky

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from Earth if it just wasn't so dim.

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Our moon is tiny in the sky, by the way.

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It's easy to think of the moon 
as this huge, baseball sized thing

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up there in the sky, but that's an illusion.

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Try this the next time you see the moon.

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Grab a sheet of notebook
paper and you will notice

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the angular diameter of the moon is the same size

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as a hole punched in a sheet of notebook paper,

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held an arms length away. 
Seriously, try it sometime.

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It shows just how cute and tiny our little moon is.

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The Orion Nebula would appear
even larger if we saw all of its light.

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And the Andromeda Galaxy--just 
a smudge in the sky to our eyes--

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but if our eyes were better at collecting dim light,

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we would see Andromeda's true extent in our sky.

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Of course, our night sky doesn't look like that.

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Distant objects are dimmer.

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That's a bummer.

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But light still wins when it comes to speed.

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Light travels at the fastest speed, in fact.

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In a vacuum, light travels 
300,000 kilometers a second.

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That's fast.

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But not really.

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I mean, not compared to how far 
apart things are in the universe.

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Sydney, Australia, is 1/14th of a light second

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away from London.

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But the Andromeda galaxy is two and half million

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light years away from London.
To put that in perspective,

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let's take a light speed journey
from London to Sydney.

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It would look like this. Ready? Three, two, one...go!

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Nice. Alright, alright. Here's
the Andromeda galaxy, okay?

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Now, relativistic effects 
aside, let's take a look at

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what it would look like to travel toward

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the Andromeda galaxy at the speed of light.

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Are you ready? Alright. Three...two...one...go!

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(sighs in annoyance)

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Yeah. I mean, seriously, it's pretty lame.

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Even at the speed of light, 
the fastest speed possible,

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a year from now, we won't even 
be a millionth of the way there.

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That's how far away Andromeda is.

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It's almost sad in a way.

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But this brings us back to
the rolling shutter effect.

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The Andromeda galaxy is huge.

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It's more than a hundred thousand light years across

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and our view of it is tilted, 
which means that on the plane

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we view it in, light from the back represents

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what Andromeda looked like
thousands and thousands of years

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before what light from the front represents.

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Changes in its appearance reach 
us sooner from the front

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than from the back. Andromeda is rotating,

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spinning at hundreds of kilometers
per second in some places.

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Now, a lag between light coming
from near and far points

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on a spinning object results in a skewed image.

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The rolling shutter effect on 
a cosmic scale applied, to say,

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a Chess board, seeing the front ahead

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of the back is pretty trippy and dramatic.

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So does that mean we see
wobbly, funhouse mirror,

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rolling shutter effect versions of Andromeda

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and other distant galaxies? 
Well, technically, yeah.

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But the distortion is negligible.

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It may as well be ignored. Why?

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Well, the speeds used in these
visualizations are not to scale.

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On average, yes, matter within galaxies 
orbits the galactic center at hundreds

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of kilometers per second, 
but galaxies are so huge,

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it takes them hundreds of millions of years

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to complete just one rotation. In other words,

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the lag between light reaching
you from near and far points

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on a galaxy is nothing compared 
to how much time it takes

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matter in the galaxy to travel that same distance.

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In the case of Andromeda, 
if you insisted on seeing

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Andromeda as it really is,
that is, corrected for any lag

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caused by the fact that the speed of light is finite,

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the most extreme points on 
the galaxy would only need

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to be adjusted by about a ten-thousandth
of the width of any image.

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In this case, less than a pixel.

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So it's not a big deal.

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But it's not a nothing deal. It's real.

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In fact, everything we look at is, in some way,

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distorted by the fact that
the speed of light is finite.

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Your own feet are about five
to six light nanoseconds

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away from your eyes,

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which means, when you look at your feet, 
you're seeing where they were,

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5-6 nanoseconds ago,

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5-6 nanoseconds in the past.

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Of course, a delay that brief 
is pretty much undetectable,

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but it is calculatable. If it makes 
you feel a little sad to know that,

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even with the sharpest mind 
or the best instruments,

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appearances still depend on where you are,

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that optical phenomena ensure
appearances are always relative...

165
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don't feel bad. We call the people
closest to us our relatives.

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We're really just a family.

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A big family of reference frames that, like a family,

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don't always agree, but do have
plenty of cool things to look at.

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I'd like to think my editor, Guy, for help with

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the rolling shutter effect in this video.

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And I'd like to thank you because, as always,

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thanks for watching.

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