How do you recognize where you are? We humans highly rely on visual information. Without opening your eyes, how do you know where you are? You could touch something within arm’s reach. You could focus on the noise you hear. You could also try to use your sense of smell. I doubt anyone would try to use their sense of taste to know where they are. These are generally called our five senses; vision, touch, hearing, smell, and taste. We recognize the world around us based on these five senses. Visual information is primarily received by photoreceptor cells on the retina in our eyes. We have three kinds of photoreceptor cells and each senses the light around a specific wavelength. Roughly, these wavelengths are: red (700nm), green (550nm), and blue (400nm). When the light around 700nm reaches the retina, only red photoreceptor cells are activated while the others are not, and this is how we perceive red light. White light can activate all three types of photoreceptor cells, thus we recognize it as colorless daylight.
In other words, not all light is sensed by humans. We only sense the light within the range between certain wavelengths, called visible light (from short to long wavelengths: violet-blue-green-yellow-red), and these are the wavelengths we can perceive. The lights just below and above this visible range are called ultraviolet and infrared, respectively. Because they are outside of the visible range, we cannot sense (or more accurately, see) them without specific goggles or cameras that transduce the invisible light into the visible range. When I was a kid, I could not digest this scientific reality. I thought that we could see all that existed around us. But reality is the opposite. Our senses constitute the existence around us, not the other way around. Something we can sense, we recognize it as existence. Anything we cannot sense, it is not recognizable. If unrecognizable, anything does not exist.
The amazing and probably unique ability of humans is that we are able to conceive that which we cannot sense, by using words. ‘Time’ is a typical example. We can conceive the past and the future because of our words. Not only have we conceived it but we have also developed the tools to visualize it with calendars and clocks. Once someone conceives something and puts a name to it, it becomes conceivable for others and is recognized. Because our world is captured by words, each language differently recognizes the world with a lot of commonalities. For example, something valuable in a certain community tends to have more specific words to recognize its subtle differences like Eskimo words for snow. The words related to the subject are highly enriched but not necessarily associated with the real differences everyone can sense. Those differences are clear within the community but often unrecognizable for outsiders.
Hearing languages is also very interesting. Like vision, we can only sense (or hear) a certain range of sound frequency. Frequency that is too high or too low (i.e. ultrasounds and infarsounds, respectively) cannot be captured by the human ear. It is also known that high-pitch sounds can only be captured by younger age groups but it is indiscernible for old people. As humans, we have a standard auditory range. That being said, we are not a simple auditory machine. If we hear someone speaking in a language that we know, we recognize the sound emanating from their vocal cords as distinct words. If we don’t know the language spoken, all we hear is simply noise. Furthermore, what amazes me is the ability to distinguish certain pronunciations. For a Japanese native such as myself, the sounds of ‘L’ and ‘R’, or ‘B’ and ‘V’ are very difficult to distinguish from each other. I can hear them but cannot recognize the differences. In these cases, sensing is not equal to conceiving. To conceive the differences, training is necessary. Without training (i.e. acquisition of a language), those existing differences cannot be recognized.
Amongst the ancient Greeks, the world is composed of the four elements: Earth (soil), Water, Air (wind) and Fire (flame). I am not sure ‘air’ in this context holds the same meaning as the “air” we know now. Rather, it probably means ‘wind’ or ‘sky’. If so, all of them can be seen or sensed. I wonder who first came to conceive “the air”. Counting and mathematics can also be seen in the same vein. Human rights, national borders, values, etc., all those concepts relating to modern society are all inventions of humans to support the growth and development of human communities. None of these concepts can be sensed. Only education using language makes them conceivable. In other words, they would never exist without proper education. Physical existence or non-existence is not what matters. Conceivable, unconceivable, existence, non-existence, and imagination. What are the boundaries? I am not sure. For example, think about tele-communication platforms like Zoom. The concept of such a form of communication used to be a simple imagination in scientific fiction. Before that, such things were not even imaginable. But once it was imagined, a word was created to describe it. The concept could be conceived and shared with others. Then, eventually it physically exists. Our society keeps evolving through the expansion of our conceivable notions.
I like science because we have a chance to conceive something previously unconceivable. This is clearly different from what we deem as the ‘unknown’. In the case of the ‘unknown’, the question is already recognized but its answer is unknown. On the other hand, there is no way to recognize the unconceivable. This reality makes me very excited as a scientist. Like any other form of art, music, or even philosophy, what was previously inconceivable could suddenly become recognized by one person and then shared with others. We refer to these processes as creativity, discovery, or innovation. Human history is an expansion of the conceivable in our mind. Ironically, this ability to conceive also creates earthly desires that often causes us to suffer. In Buddhism, by focusing on the current moment and on our own senses, we will be released from this incessant suffering that is created by our ability of conceiving. We build our society based on this ability that is much larger than the world we can sense. It keeps growing without evolving our own senses. We live in an imaginary world that any other animal could never see and understand.
Thanks to Vera Lynn for English editing.
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