When you look at the room around you, are you seeing it as it really appears out there – in the real world? Or, is what you see just an illusion?
This might sound like a philosophical question, but it’s not. In fact, it can be answered using simple physics – the kind of physics you already understand.
Let’s say you’re in a room.
If you’re already in a room, that’s great. Take a picture of that room, as it appears in front of you.
I know you have a camera phone somewhere in your vicinity. Don’t lie to me. Take it out, open the camera app, and take a picture.
Now look at that picture. Does this picture represent what the room actually looks like? In other words, does this picture describe the space in front of you as it truly is?
To get a better idea of how to think about this question, let me ask you this – what’s in the room?
Let’s say I put you in a very specific room.
This particular room is a 10 foot by 10 foot square with four walls, one door on the east side of the room, a table on the west side of the room and a chair on the north side of the room. There is one light in the center of the room, directly above you.
Imagine yourself facing north, towards the chair.
We’ll ask our same question, again: What’s in this room?
There’s the chair directly in front of you, of course. The door, the table, and the light are all also in the room, but just outside of your peripheral vision. So they’re there, but you can’t see them.
But what else?
Well, for starters, there’s also all the air that you’re breathing right now.
There are about 80 pounds, or 36 kilograms, of air in your average 10’ x 10’ x 10’ room. That is, if you’re in a room that’s ten feet wide, ten feet long, and ten feet tall, the air around you weighs the same amount as a child.
…and you can’t see any of it.
Already, that tells us that we’re not seeing all of reality. Air is a physical object in front of us, and yet we can’t see it.
in·vis·i·ble inˈvizəb(ə)l/ adjective 1. unable to be seen; not visible to the eye.
From that, we can come to a rather mundane conclusion: that we can’t see things that are invisible to us.
Sounds redundant, right?
But… what about visible things? Surely, if something is visible, and it’s in front of us, and there’s nothing blocking our view of it, we should be able to see it, right?
Can we say: we are not viewing the invisible parts of the room accurately, but we are viewing the visible parts of the room accurately?
|We are accurately viewing: the visible world.|
|We are inaccurately viewing: the invisible world.|
Is this correct?
The seemingly obvious table above is completely false.
Stop and think about this – what else is in the room with us?
There’s: the air; the chair; the table; the door; the floor; the walls; the ceiling; and the light bulb above us… but what else?
Need a hint?
It has to do with the last item in the list above.
How about now? Did you figure out what else is in the room all around you?
Or rather, photons.
There are trillions upon trillions upon more trillions, and then extra trillions of photons everywhere in the room around you, zipping by at 299,897,458 meters per second.
If you could freeze time, and halt all of those photons of light as they travel through space, you would see that they permeate every single square inch of space in the room. They’re everywhere. Just… everywhere around you. There are trillions of them in a pocket of space just above your head… and to your right side… and your left side… and behind you… and directly in front of you.
Here’s a question I want you to think carefully about – can you see those photons?
- Do they belong in our visible category, or do they belong in our invisible category?
- Do we see them accurately, or do we see them inaccurately?
- And, would visibility directly correlate to accurate viewing?
Before we can answer these questions, we have to ask a few more.
Can you see the light in front of your face?
For our purposes today, when we talk about light, let’s only consider the photons – ie: light waves – that are in the visible spectrum.
There’s X-rays, and infrared light, and radio waves and all sort of things, but for now, let’s focus on just those in the visible spectrum – or what we can visualize as the familiar rainbow of colors.
In fact, we can make it simple. We’ll put visible light waves, or photons, into the visible category, and all other light waves, or photons, in the invisible category.
Let’s just think about the visible photons that are in the room. Can we see them?
We know we can’t see the air all around us. But, what about the photons? Are they also invisible? Can we see all those trillions of photons racing through the air? Can you see the light waves that are two inches in front of your face?
Let’s look at the same idea another way: Can you see the photons that are two inches in front of you through the photons that are one inch in front of you?
Oddly, the answers to these seemingly similar questions are quite different.
When we ask if all those photons, that we don’t typically think about, are invisible – the answer is no.
If we ask if we can see photons – the answer is yes. They’re the only things we can see.
But, when we ask if we can see the photons around us – the answer is no.
When we ask ourselves if we can see the photons two inches in front of our eyes through the photons one inch in front of our eyes, the answer is… completely irrelevant.
Let’s take a closer look at the last one first…
Are light waves see-through?
When we think about things as invisible, we often think about it in terms of our being able to see other objects on the other side of the invisible thing. We can see through it.
So… how can it be irrelevant when it comes to photons?
Remember – photons are light particles.
We could also reword this question to say – can we see the light two inches in front of our faces through the light one inch in front of our faces.
But here’s where you run into a rather counterintuitive fact of reality: you can’t see the light two inches in front of your face at all.
This is whether anything is in the way or not.
You also can’t see the light, or the photons, one inch in front of your face.
Your scope of vision just doesn’t reach that far.
So, just how far does your vision extend?
It turns out that you can’t see a single thing outside of your own pupils.
Your entire world view is limited to a thin membrane of cells inside the dark cavern of a pupil you have right in the center of your eyeball.
Right now, you can imagine a thin wall of photons hurtling through space at almost 300 million meters a second, destined to smack straight into the cells lining your retina at tremendous velocity.
Let’s picture that wall of electrons headed for us in slow motion. Imagine you can follow it through space in a series of frames as it gets closer and closer to our eyeballs. We’d be tempted to freeze time right as that wall hit our eyes – but we actually have to stick with it as the photons pass through the lens of our eyes, travel through the pupil, and then slam into our retinas. It’s only right at that last step that we can freeze time.
When we freeze time, we can ask ourselves – how much of our world are we seeing in this instant?
Can we see all the way to the back wall? Can we see the chair? Can we see the light waves that are two inches in front of our faces?
The answer is that we can’t see any of these. We can only see that thin layer of photons making contact with the cone and rod cells in our eyes. We can’t even see a fraction of a fraction of an inch more than that. We can’t see outside our own eyeballs.
In fact, we won’t actually be aware that we saw those photons making contact with our retinas until approximately 80 milliseconds into the future.
So, then… When that light hits your eyes, what’s visible? Is it the chair a couple feet in front of you, or the photons inside your pupil?
The truth is that you can’t see the chair, and you never will.
You can’t see the chair, but can you at least see the light?
“Ok, ok, I get it. The things I think I’m seeing are really just the photons bouncing off objects in the room. But, I’m at least seeing the photons accurately, right?”
If you’re talking about the visible spectrum photons inside your eye, the answer is yes.
But if you’re asking if the light inside your eye gives you an accurate representation of the photons outside your eye, the answer is a resounding no.
What if you could stick a piece of film directly in front of your face… a special film that would register all the photons that it touched in that thin slice of space?
Every photon in the slice of space an inch before your eyes would be picked up by the film in the same way your eyes pick up light. That is, if there’s a photon that your eye would register as white in front of you, the film will register it as white. If there’s a photon that your eye would register as green, the film will register it as green.
Now. If you processed this film into a picture, would it look roughly similar to what you see with your eyes? Just the visible light, mind you. Would it still basically reflect the chair and the wall in front of you?
What you would really see is a complete visual disaster.
To see why, let’s give the little photons zipping around our room some names.
This is Fred, the photon.
Let’s think about that light bulb sitting right above our heads in this make believe room for a second.
That light bulb is generating photons.
Let’s name one of them Fred.
While we’re at it, we’re also going to say that the chair in front of us is made of plastic, and paint it blue.
Fred has just been born out of the light bulb and comes hurtling out at 300 million meters per second. Fred, coming from the angle that he is, hits the chair, loses some of his energy, and becomes a photon with a wavelength of 450 nanometers.
If that sounds technical, don’t worry about it. All you need to know is that when Fred hits your eye, you’ll see the color blue. “The chair is blue,” your eye says to your brain.
Now let’s name another photon. This one we’ll call George. George is ejected from the bottom of the light bulb, hits the ground, becomes red – because let’s say you have red carpet for whatever reason – and bounces back up.
You don’t see George because you’re not looking down at the carpet, but George is there.
Let’s follow just one more photon – Mary.
Mary shoots out of the light bulb, hits the table to your side, which we’ll say is orange, bounces off, and continues hurtling through space towards the opposite wall. On Mary’s trajectory from the table to the wall, she’ll pass right in front of you, just like George.
For the sake of a clean visual, let’s say that the table is also at eye height. For some reason. (Because I’m too lazy to go back and change this example to something else).
We’re all set up.
Now, let’s put that film back in front of our eyes. Let’s say that this film is a foot wide, a foot long, and a few nanometers deep.
We’re going to pretend that Fred, George, and Mary all make contact with this film at the same time (but from different angles).
What does our film register?
It registers blue, from Fred, coming from the chair. It registers red, from George, coming from the carpet. And it registers orange, from Mary, coming from the table.
The film sees blue, red, and orange.
But what does your eye see?
Will your eye see the same picture that would register on this thin slice of film?
Not even close.
The only color we’ll see is blue… from Fred, heading straight for our retinas.
Even though there are visible blue, red, and orange photons right there, right in front of our eyes, we won’t see most of them.
There is a cacophony of incomprehensible, jumbled visual light right in front of us that is an incomprehensible mess – and we can’t see it.