Which of the two squares seems lighter to you, A or B? For me, B is clearly lighter. And you surely agree. But the strange fact is that both squares… are actually identical. Today we will talk about our distorted perception of reality, the so-called “overview effect”, and how today, exactly 10 years ago, a change in perspective changed my life forever. So, if you dare, I invite you to watch this episode. Who knows? Maybe it will change your life too.

The previous illusion is called “Adelson’s checker shadow illusion”, and it occurs because our brain doesn’t perceive colors in isolation, but in relation to the surrounding context. That is, if you see the two squares separately, there is no doubt that they are identical. But as soon as you add in the context, suddenly B seems lighter than A.

In some way, our brain is trying to help us. It notices that there are some objects in the light and others in the shadow, so, in order to help us see them all well at the same time, it makes the ones in the shadow appear a little lighter. But of course, in trying to help us, the brain ends up distorting our perception of reality.

And this is just one example. The truth is that our brains are tricking us constantly.

Our perception of reality

Another way you can see how our brains trick us in order to help us is the famous Mariotte test. Cover your right eye, and look at the red circle. Then slowly move closer to the screen. At a certain point, you will notice that the blue circle disappears completely.

The reason the blue circle disappears is because we literally have a blind spot in our eye, in the area of the retina where the optic nerve connects to it. Right there, we don’t have light-sensitive cells. However, you don’t notice their absence, as the brain fills in those blind spots without you even realizing it.

But what we think we see is not only affected by the visual context, but also by sound. For example, in this animation, there are two little balls that pass through each other in the middle of the image. However, when you see the same animation accompanied by the sound of two billiard balls colliding, suddenly, our brain makes us believe that the balls do not pass through each other, but rather collide in the middle.

And this type of distortion in reality not only affects what we see and hear, but also how we think. We tend to believe that our decisions and opinions are the result of our own logical and objective conclusions. But this is also an illusion.

Magicians take advantage of this when doing their tricks. For example, if a magician tells you to pick a card, he already knows from the beginning which card he wants to keep. If you choose that card, the magician will say “Perfect, let’s keep that card.” And if you choose the other one, the magician will say “Perfect, let’s discard that card.” You believe that the decision was yours… And then you’re surprised when they pull out the king of spades from behind your ear.

In short, our perception of the world around us is full of small distortions. Luckily, to identify them, sometimes all it takes is a small change in perspective.

That’s what happened to me 10 years ago. And now I’m going to tell you how it happened. But first, we need to travel back in space and time.

The overview effect

Australia, 2014. It was a peaceful night on the outskirts of a small town, 400 kilometers west of Sydney. I was working on the Parkes Radio Telescope, a 64-meter diameter satellite dish, which has been observing the sky since 1961: pulsars, quasars, fast radio bursts…

Parkes was also one of three antennas that captured the signal from the Apollo 11 mission, allowing the entire world to see in real time humanity’s first steps on the moon. In Australia, Parkes Observatory is affectionately called “The Dish”.

Parkes is mostly used to observe pulsars. That is, neutron stars rotating very quickly, which, when viewed from Earth, appear to be emitting pulses of radio waves, as if they were interstellar beacons. Normally, when Parkes observes a pulsar, it does so for several hours continuously, slowly and patiently following the star’s path across the sky.

At one point during the night, I went out to see that majestic radio telescope illuminated in the middle of the darkness, right underneath the Milky Way. It was a spectacular image. If you have never been to the southern hemisphere, I can tell you that the night skies there are truly impressive. On a clear night, far from city lights, you can see the center of the Milky Way with the naked eye, as well as two other neighboring galaxies, the Small and Large Magellanic Clouds. And that night in 2014 indeed boasted a beautiful starry sky.

Parkes was observing a pulsar in a lower region of the sky, near the horizon, so that the edge of the Dish was almost at ground level. I went over to touch it.

Then, as I felt the constant vibration of Parkes rotating slowly, I noticed something curious.

From my perspective, the Dish was moving very, very slowly, following the position of that specific star in the sky. But the star was several thousand light years away, and so its location in the galaxy, as seen from here, had barely changed in hundreds or thousands of years. That meant that Parkes was actually looking at a fixed point in the galaxy. So, really, that subtle vibration I felt with my hand was not from the movement of the Dish.

It was the Earth that was moving under my feet.

Obviously, I already knew that the Earth rotates, but somehow I had never felt it as vividly as I did then. Astronauts sometimes talk about the so-called “overview effect”. It is a fundamental change in the way reality is perceived, caused by viewing planet Earth from the outside, to observe it as it really is: a little blue dot, fragile and isolated, in the immensity of space. For me, considering that I will probably never go into space, that night in Parkes I got to have my own “overview effect” moment.

So, was that the change in perspective that changed my life forever? No.

In fact, the event that changed my life took place just a few days later, on October 25th, 2014. But I warn you: the story is much less poetic.

The day something “clicked” in my head

We often hear incredible stories of someone who climbs Mount Everest or survives a plane crash and decides to dedicate the rest of their life helping others.

In my case, the day that changed my life forever, I was… lying in bed on a Saturday morning, watching videos aimlessly on my phone. (If you are also lying in bed right now, leave me a comment!)

That day, I saw a video that a former coworker had shared on Facebook. I just went to his Facebook wall now, actually, and searched for the exact day he shared it, and realized that the post is still there, with exactly zero likes.

You see how ungrateful I am? I watch a video that changes my life forever, and I don’t even give it a single miserable like. As my grandmother would have said: I am a “descastao”.

The video itself lasts one hour, and is a talk by the American psychologist Melanie Joy, author of the book “Why We Love Dogs, Eat Pigs, and Wear Cows.” In the video, she talks about what she calls “carnism”, the belief system that conditions people to eat certain animals and not others.

I literally finished watching the video, turned to my girlfriend and said: “I think I’m going to go vegetarian.” And she replied: “I think you’ve gone insane”.

Sure enough, something had “clicked” in my head. And that day, I really did become a vegetarian. And soon after, I went vegan. And later, I realized I could have a bigger impact on the world by changing my career, and I left astrophysics. And soon after that, I became interested in effective altruism, and discovered that some ways of helping were more effective than others. And shortly after that, I decided to start this channel. And then, as I explained in a previous episode, I signed a lifelong pledge to donate at least 10% of my income to the most effective charities working to reduce human and animal suffering.

In short, that day I not only changed my diet, but I forever changed my way of seeing the world.

But what the hell happened to me that day that caused this snowball of changes in my life?

The question that changed my life

I am not going to address the problem of animal suffering today. I already dove deep into the subject in the last episode of AltruFísica. What matters here is that my perspective on the topic changed drastically when I watched that talk by Melanie Joy. As she said herself, when you change your perspective, “You don’t see different things, but you see the same things in a different way.”

It’s a change similar to the one Neo undergoes in The Matrix, when he takes the red pill from Morpheus and begins to see reality as it is. In fact, Vox co-founder Ezra Klein calls this shift in perspective “Taking the green pill”, and, as he says: “A world that seems completely normal becomes a horror show”.

I often wonder what exactly caused that change of perspective in me. Was it the images of slaughterhouses, or the data on how many animals die each year to produce food? It was undoubtedly a combination of many factors. However, what affected me the most was asking myself a seemingly simple, innocent, but very profound question: “Could I be biased?”

In short, being biased means having an incomplete or unbalanced view of reality.

The video that changed my life made me remember all those times when my ex-colleague (yes, the one who shared the video that I didn’t even “like”) had talked to me about the problem of factory farms. And I remember that I used to respond with the first things that came to mind: “Yes, but where do you get your protein?” “Veganism is extreme, virtue is in the middle,” “Well, an uncle of mine has a farm where the animals live very good lives, so….”

But after watching Melanie Joy’s video, I changed my perspective, and I saw myself saying all those things knowing that deep down… I had no idea what I was talking about! I was affected by countless biases, which, as I learned shortly after, actually have names, for example: the “status quo bias”, the “middle ground fallacy”, or the “availability bias”.

Basically, whenever I gave those answers, I wasn’t searching for the truth, but rather trying to justify my opinion. I called myself an “astrophysicist,” and yet I was betraying one of the most fundamental principles of a good scientist: the objective search for the truth.

A new perspective

That night at the observatory, a small change in perspective made me notice the Earth turning under my feet for the very first time. And exactly a decade ago, a single YouTube video changed the way I viewed that planet forever.

“Could I be biased?” This simple question changed my life then, and has caused me to change my perspective on many other occasions. Unfortunately, what we cannot change is our brain: squares A and B will continue to look different to us, and from time to time a magician will pull out a king of spades from where we least expect it. But if we at least regularly ask ourselves this question, we will form a slightly more accurate view of the world.

Now, it’s finally time to show some gratitude. Even if it’s a decade late, I’m going to leave a like and a comment on that video that my ex-colleague shared, and which changed my life forever.

If you liked this video (regardless of whether it changed your life or not!), I also invite you to give it a like, or leave a comment. And if you want to see more videos about the Universe, or how to make the world a little better, you can also subscribe to my channel. That way, I will be sure to have the pleasure of seeing you again in the next episode of AltruPhysics.