On what human sense are sensing: We simulate reality

What we sense really isn't exactly reality. The brain-mind has to create illusions and narratives to explain things that are very probably not fully understandable because they far too complex for probably any form of life to comprehend. An article by Discover Magazine goes into this for a general audience: 

How Quantum Mechanics Lets Us See, Smell and Touch

How much of the quantum world can we experience in our daily lives? And what sort of information can our senses glean about the true nature of reality? After all, as the origin of the theory itself makes clear, quantum phenomena can lie just under our noses. In fact, they may be taking place right inside our noses.

The Quantum Schnozz

What’s going on in your nose when you wake up and smell the coffee, or the slice of bread browning in your non-lethal toaster? For such an in-your-face sensory organ, the nose is poorly understood. No less a luminary than Enrico Fermi, who built the world’s first nuclear reactor, once remarked to a friend while frying onions that it would be nice to understand how our sense of smell works.

So you’re lying in bed, and someone has thoughtfully brewed some freshly ground Sumatran dark roast. Molecules from the elixir waft through the air. Your inhalations draw some of these molecules into a cavity between your eyes just above the roof of your mouth. The molecules stick to a layer of mucus on the upper surface of the cavity, embedded with olfactory neurons. Dangling from the brain like the tentacles of a jellyfish, olfactory neurons are the only part of the central nervous system constantly exposed to the outside world.

What happens next isn’t quite clear. We know the molecules bind to some of the 400 different receptors on the surface of the olfactory neurons; we don’t know exactly how that contact creates our sense of smell. Why is smell such a difficult sense to understand?

“In part, it’s the difficulty of setting up experiments to probe what’s going on inside the olfactory receptors of the nose,” says Andrew Horsfield, a materials scientist at Imperial College London.

The conventional explanation for how smell works seems straightforward: The receptors accept very specific shapes of molecules. They’re like locks, which can be opened only by the right keys.

But there’s a fundamental problem with the lock-and-key model: “You can have molecules of wildly different shape and composition, which all give you the same odor perception,” says Horsfield. It seems that something more than shape must be involved, but what?

A controversial alternative to the lock-and-key model suggests our sense of smell arises not just from the shape of molecules, but also from the manner in which those molecules vibrate.

Feeling Your Way

Now back to that cup of coffee. The cup feels substantial, a solid chunk of matter firmly in contact with the skin of your hand. But that’s an illusion: We never really touch anything, at least not in the sense of two solid slabs of matter coming together.[1] More than 99.9999999999 percent of an atom consists of empty space, with nearly all its stuff concentrated in the nucleus.

When you exert pressure against the cup with your hand, the seeming solidity comes from the resistance of electrons in the cup. Electrons themselves don’t have any volume at all — they’re just fleeting, zero-dimensional flecks of negative electric charge that surround atoms and molecules like clouds. And the laws of quantum mechanics limit them to specific energy levels around atoms and molecules. As your hand grasps the cup, it forces electrons from one level to another, and that requires energy from the hand’s muscles, which the brain interprets as touching something solid.

Our sense of touch, then, arises from an exceedingly complex interaction between electrons around the molecules of our bodies and those of the objects we encounter. From that information, our brain creates the illusion that we possess solid bodies moving through a world filled with other solid objects. Touch doesn’t give us an accurate sense of reality. And it may be that none of our perceptions match what’s really out there. Donald Hoffman, a cognitive neuroscientist at the University of California, Irvine, believes that our senses and brain evolved to hide the true nature of reality, not to reveal it.

“My idea is that reality, whatever it is, is too complicated and would take us too much time and energy [to process],” he says.

Hoffman likens the picture our brain constructs of the world to the graphical interface on a computer screen. All the colorful icons on the screen — the trash can, the mouse pointer, the file folders — bear no resemblance at all to what’s really going on inside the computer. They’re abstractions, simplifications that allow us to interact with complex electronics.

In Hoffman’s view, evolution has shaped our brains to operate in much the same way, as a graphical interface that doesn’t reproduce the world with any sort of fidelity. Evolution doesn’t favor the development of accurate perceptions; it rewards ones that enhance survival. Or as Hoffman puts it, “Fitness beats truth.”  

So while one organism might construct a more accurate representation of reality, that representation doesn’t enhance its survivability. Hoffman’s studies have led him to a remarkable conclusion: “To the extent that we’re tuned to fitness, we will not be tuned to reality. You can’t do both.”  

As Hoffman’s work shows, we haven’t yet come to grips with the full meaning of quantum theory and what it says about the nature of reality. Planck himself struggled for most of his life to understand the theory he helped launch, and always believed in an objective universe that exists independently of us [I believe that too]. He once wrote about why he decided to go into physics against the advice of his mentor: “The outside world is something independent from man, something absolute, and the quest for the laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life.” Maybe it will take another century, and another revolution, to prove whether he was right, or as mistaken as Professor von Jolly.

The article is long and this is only about half of it. But I hope that one can get some feel for how complicated the concept of reality and human perceptions of it are. 

Footnote:

1. I have a quibble with the argument that we do not touch a solid thing. That feels wrong to me. When our hand picks up a rock or other solid thing, there is very close contact. Atoms or molecules of both are coming up against each other and a few diffuse into each other. Atoms of solid gold and other metals in contact with each other diffuse into each. Measured diffusion rates for metals was being published long ago, e.g., this 1950 paper, The diffusion rates of some metals in copper, silver, and gold. An 1896 paper commented: "The diffusion of molten and solid metals has long demanded investigation, their molecular mobility being of great interest in relation to the constitution of matter, and its results of much industrial importance." 

Just because atoms and molecules are mostly empty space, does not mean that atoms and molecules do not interact at the atomic level when they come in contact with each other. If the mixing of atoms and molecules of two different solids, liquids or gases does not constitute touching, then I don't understand what touching means. 

Acknowledgment: Thanks to ulTRAX for bringing this article to my attention.