Tenjou Nanami taught me the word qualia.
She taught me a lot of other difficult concepts, like about philosophical zombies and inverted qualia too. Of course, at the time we’d just entered junior high, and Nanami was probably paraphrasing what she read in books or on the internet, so I can’t say much about whether we really knew what we were talking about.
To give one example, at one point, Nanami called qualia “emergent,” and at another point, she said that qualia were not things that “emerged.” So I asked her if she hadn’t contradicted herself, and she snapped back shamelessly, “There’s nothing odd about that! Science is progressing in leaps and bounds!” But I didn’t know what emergent meant in the first place.
Whether or not we knew what we were talking about, Nanami was sincere in her desire to learn more about this stuff, and I was interested too. So, kids that we were, we talked about it to the best of our abilities.
Nanami explained qualia like this: “I think, when you get down to it, qualia are like ‘A picture is worth a thousand words.’”
“You mean, like, the saying?”
“That’s right. In other words, no matter how much you know about the color red, you’ll never understand it until you see it for yourself. Conversely, if someone’s never actually experienced the color red for themselves, no matter how much of an expert they might be on it otherwise, you couldn’t say they really know what ‘red’ is. You see what I’m saying? Hundreds of words won’t get you to true knowledge, but one look will. That one look is qualia, I think. Not that I’m really sure what that one look consists of…”
Whether or not we understood them, we talked about these matters with all the seriousness we had. We were compelled.
At one point, we talked about quanta and Schrödinger’s cat.
“You know quanta?”
“Like electrons and molecules… The minimum unit of stuff, right?”
“Right. Humans and stars and everything in the universe are made of materials called quanta. And quanta are particles, but they also have the properties of waves. You follow me? What I’m saying is they’re simultaneously matter with form and energy without form. Because they’re waves, they’re not definite objects, but probabilities. They’re expressed by concentrations of probabilities. That’s what quanta are.”
“Concentrations of probabilities?”
“Right, like, is the probability there high or low? You see, it isn’t ‘determined’ whether quanta are there or not until you measure them. It’s not that you can’t know they’re present, it’s just that it’s really indeterminate. It’s when you measure them that for the first time their existence is ‘determined.’ So until you measure them, you have to consider them in terms of high or low probabilities of being there. Those are the properties of quanta. It might sound strange, but this isn’t science fiction. This is what scientists think reality is. ‘You don’t know until you see it’—our bodies are made of that, multiplied by a very large number.”
“Huh.” That was all the reaction I managed, largely because I had a hard time wrapping my head around it, honestly.
But that didn’t slow down Nanami. “So, Hatou, do you know of the thought experiment they call ‘Schrödinger’s cat’?”
“Uh…that kind of rings a bell, I think…”
“To put it simply, you prepare a box that releases a lethal gas when a switch is pressed, and you place a cat in it. Then what happens to the cat?”
I didn’t see where Nanami was going with this. I hesitated and then answered, “The cat’s alive until someone flips the switch, and then it’s dead, right?”
“Right. Normally that would be the case. But in our thought experiment, the one flipping the switch is not someone, but a quantum. So our device is one in which, if the quantum is there, the switch is flipped, and if it’s not, the switch remains untouched. But here’s the thing: quanta are probabilistic and not determined until they are observed. That means that the switch state determined by the quantum is also probabilistic until it’s observed. Until you open the box and look inside, the switch exists simultaneously in an on and an off state, which means that the cat whose life is determined by the state of the switch also exists simultaneously in a probability of being alive and a probability of being dead until you open the box. Do you see what I’m getting at?”
“Um…”
“Here’s what this experiment tells us. People think quanta have strange properties at the micro level, but it doesn’t apply to the macro world—that is, the real world. But they’re wrong! Just as a quantum determines the state of this switch and the state of the switch determines whether the cat is alive or dead, it only makes sense for these properties to apply to the macro world as well. If that’s really how quanta are, it only makes sense that we should be like them, existing simultaneously alive and dead until we’re observed. That’s the point of Schrödinger’s cat.”
Once that sunk in, I yelped in surprise. “What?! But here we are! We exist! We’re not probabilities. We’re obviously here. We’re not about to disappear whether or not someone sees us.”
“Are you sure?”
“Uh… What do you…”
“Well, you raise a good point. That was the conclusion of Schrödinger, who invented this thought experiment. He argued that since there obviously couldn’t be a cat that was both alive and dead, it followed that quanta couldn’t simultaneously be present and absent. But the physicists, like, at Copenhagen disagreed. They said that given that quanta are probabilistic, the only problem with having a cat alive and dead was your inability to realize the thought experiment itself. They said if you could eliminate all the systemic obstructions, the external factors like heat and fluctuation, if you could just perform the experiment properly, then sure, you could have your alive-and-dead cat. And now that’s the dominant view. Apparently, Schrödinger quit physics toward the end of his life over it. Well, that’s just what I’ve heard, but it would be pretty funny if that was true, wouldn’t it? That the one who established the Schrödinger equation, the foundation of quantum mechanics, would have been unable to accept it!” Nanami was getting a wild smirk and was about to continue rambling until I interrupted her.
“Wait. Are you saying we actually are probabilistic? Like without those ‘external factors’ or whatever, we’d stop being clearly alive or dead the moment someone took their eyes off us?”
Nanami shrugged. “Good question.”
“What do you mean, good question?”
“We just don’t know. All that we know is that quanta behave probabilistically. We don’t know why they behave that way, what process they undergo, or why it’s only on the micro level. There’s still no complete answer. Honestly, we don’t know what it means for the state of a quantum to be determined—wave function collapse, they call it—we don’t know what ‘observation’ is,” Nanami continued.
“In the case of Schrödinger’s cat, at what point is the cat observed? When a person opens the lid and sees it? When the sight reaches their brain? Or when the cat feels something? Or what if the person who opened the lid of the box was in a bigger box? And what if there was another person outside that box? If the person and the box were in a big box and there was a person observing it, when would it be determined whether the cat was alive or dead? Would it remain indeterminate until the last person ‘opened the box’? We know that on the micro level, quanta exist in a bizarre state of being both waves and particles. We’ve confirmed that molecules, which are combinations of quanta, exhibit quantum behavior. We might even be able to identify it in viruses. Then why can’t we spot it in the macro world? If it’s true that presence is determined by observation, if there really is such a thing as wave function collapse, then when does it happen, and at what stage? Why? How? There are various interpretations, but we don’t really know. All we have are the results. And some say we’ll never know the process, no matter how far science advances.”
In the old days, scientists thought that scientific progress would solve all the world’s mysteries, but modern science says that’s not the case. Why? Because in the micro world, just measuring something changes its state. And such little changes could exert big, complex changes on reality. There’s a limit to what we can know, and no matter how far science advances, we’ll never have 100 percent accurate weather forecasts, apparently—at least under the current scientific system.
“Anyway,” Nanami went on, “sorry for the long lecture, but see, the point I’m trying to make is, this world isn’t as certain as we think it is. Here’s another theory, for example: quanta aren’t probabilistic and presence isn’t determined at the moment of observation. Instead, the universe is composed of an inconceivable number of parallel worlds that interfere with each other at the micro level to cause quanta to behave in strange ways that appear probabilistic.”
“Parallel worlds?”
“That’s right, parallel worlds! Worlds that are almost the same as ours, only just a little bit different. Quanta behave in strange ways because of interference with their counterparts in parallel worlds, and when the interference ends, they’re ‘determined.’ So according to this view, it is predetermined whether the cat in the box is alive or dead. It’s just that there are innumerable worlds in which it’s alive and innumerable worlds in which it’s dead. You exist separately in each of these worlds, and they’re all interfering with each other, but you can only perceive your own world. Can you buy that? Parallel worlds? It sounds like science fiction, but they’re actually seriously researching this!” she rattled off excitedly. “The wave function collapse model is called the Copenhagen interpretation, and the parallel world model is called the Many-worlds interpretation, or MWI. The many-worlds interpretation is being used as a foundation for quantum computers or something. They’re both being explored as possibilities that may or may not be true but are plausible. It’s not science fiction. This is actually the world we live in.”
If you’re laughing right now at the fact that we were some silly junior high schoolers talking about this kind of stuff as if we had any idea about it, may I kindly suggest that you go take a flying leap? Then, come back to life: have someone replace half your body with parts of a broken jungle gym and fix your damaged hand with the components of a cellular phone!