Reflections on Color, Touch, and Time: How Human Experience Deceives Us

UV image of the sun X-ray image of the sun

Until recently, whenever I saw breathtaking images of nebulae or galaxies shot in the x-ray, ultraviolet, or infrared range, I’d be somewhat disappointed that the object depicted in the photo wasn’t how that object actually “looked." (Only images taken in the visible spectrum illustrate how the objects would appear to our eyes.) What I now realize is that there isn’t one objective way that things appear. In fact, my former bias in astronomy is just one consequence of the subjective understanding of reality to which I am confined.

Take color, for example: wherever we look, there is color. Indeed color is so ubiquitous that we tend to think of it as an inherent dimension of reality. Everyday objects seem to an extent to be defined by their color. But what is color? Color is merely our interpretation of the portion of the electromagnetic (EM) spectrum that spans from 380 to 750 nm, the “visible spectrum.” Interestingly, there is nothing inherent about this spectrum of radiation that endows it with giving off these hues, since the visible spectrum is defined to be those EM wavelengths visible to the human eye. Therefore, snakes that see in the infrared region have a different visible spectrum; looking through a thermal camera would give us a sense of how snakes perceive the world. Other animals such as insects and birds see in the ultraviolet spectrum. The feathers of some birds shine much brighter with UV radiation than with visible radiation (light). It’s easy to assume that what we can’t see isn’t real (or isn’t as real as what we can see), but on the contrary, the sun’s cancer-causing UV rays and our bodies’ infrared heat waves are just as real as the yellow sunlight and yellow (or brown, white, or black) skin we see with our eyes. Moreover, chances are that there is really nothing “yellow” about 580 nm light; another animal might see the sun as being what we would call purple or green or blue.

Human sight isn’t the only subjective filter through which we experience reality; our sense of touch is just as biased. We often forget that every solid object consists of over 99% empty space. Microscopic forces between molecules add up to emergently manifest as “hardness.” If we were 1000 times stronger, perhaps hardness would not be a meaningful concept, because we could deform and obliterate any object we wanted. Conversely, if we were small insects, water would be considered “hard” since its surface would be walkable. To gain a more objective view of hardness and softness, it might help to look at the universe as consisting mostly of space, but with regions of varying density. The phone sitting on my desk is a density region where atoms gather slightly closer to each other than do the atoms in the surrounding air. The earth itself is a larger density region floating in space, which itself is not completely empty either. Such a perspective demonstrates the difficulty of truly understanding the universe in an objective sense (if there exists one).

The same conclusion can be drawn for our senses of taste, smell, and hearing. Humans cannot imagine how dogs experience the rich array of smells available to them, in the same way that dogs are incapable of imagining the myriad hues of color by which we experience the visible spectrum. Furthermore, bats and whales use sonar to map out their surroundings in a manner analogous to our faculty of sight. The point is that our understanding of the world is completely biased. Our "reality" is merely a subjective interpretation of the universe, one that we cannot escape. This revelation both astonishes and terrorizes me.

To further illustrate this, it might be useful to examine our perception of time. In this TED presentation (I strongly suggest you watch it; it partially inspired this post and I’ve seen it twice), Richard Dawkins claims that relativity might be easier to comprehend had we evolved in an environment in which we moved at near-light speeds. To us earth-bound creatures, our velocity is of such small magnitude that we never experience noticeable differences in the rate at which time flows (although we wouldn’t notice it unless we compared our environment to slower-moving ones). Quite possibly I already assume too much: perhaps time doesn’t exist at all. Some scientists and philosophers suggest that time is simply the way living organisms interpret change. If this is true, the past and future are not real; there is only an ever-changing present. (For more on time, read this Discover article—the other inspiration for my post.)

If you’re having difficultly comprehending a universe without time, you’re supposed to have trouble. This is because we are built to experience time, whether or not it exists. (As an aside to the religiously-inclined, St. Augustine proposed that God exists outside of time, and hence God can know the past and future all at once. Then one could best understand heaven not as extending eternally into the future, but rather as existing as an eternal present.)

Discarding basic assumptions about how we perceive the world is as fun as it is mind-boggling. Actually, the fun is derived precisely from the boggling of one’s mind. But as I admitted, the recognition that my universe is merely a subjective interpretation of the real thing completely terrifies me. I’m deeply troubled by how much I don’t know. While I can try taking comfort in believing that no objective understanding of the universe exists, I don’t believe it. I want to see the world the way God sees the world. But most likely I will never know; it is not my place. In the meantime, I like to think that my biased view of reality gives it meaning I can appreciate. Life is so much more beautiful with color, isn’t it?