The philosopher Parmenides, known for the philosophical school he established in his city, Elea, (in Italy) and his main disciple, Zeno, opined that the external world was, in some sense, an illusion. That there was no “reality.” Of course this seems, on its face, ridiculous. There certainly seems to be a “real” world out there. As we sit doing whatever it is that we are doing we can see, touch, hear, smell, etc. tangible items that are “out there.” If someone sticks us with a pin, the pain certainly feels real. Our senses tell us this real world that we can feel and experience is a tangible, three dimensional one of length, width, and depth.
But there is another dimension – of time, and it is an intangible one. (Einstein dealt with it in his theories of relativity.) And it may well be in this sense that the ancient philosophers viewed the illusory nature of the world of the senses. Consider the following concepts: The only “reality” we actually experience is in the present instant. We see, touch, hear, smell, and otherwise experience objects and thoughts in the infinitesimally short microsecond of time that we define as the present. After we experience something, it is in the past. Before we experience something it is in the future. Neither of these exists in the tangible world. Both are in the fourth dimension, that of time, and this is not one of tangibility. Objects or experiences in the past or future are not “real” in the usual sense of the word. We can’t see them, touch them, hear them, smell them, etc., and they only existed in the “real” world during the infinitesimal time interval during which they were in the present.
To get a better feel for the situation, let’s look at it from a few different angles:
The time continuum consists of only three parts – the future, the past, and the present. And an event that occurred in the past no longer exists; an event that will occur in the future does not yet exist; and an event in the present exists for such an infinitesimally short period of time it’s hard to conceptualize that it is “real” (or tangible in the normal sense) either.
Like sand slipping through our fingers, time slips by us. We can’t grip it or reduce its slippage, much as we might try. (I suspect that the tourist’s compulsion to take pictures is an attempt to capture the “present reality,” make it tangible, and stop it from disappearing into the intangible past.)
The situation is analogous to a motion picture where the film passes quickly over a lit aperture and is projected onto a screen. The film images before and after the aperture are not visible. Only the tiny, single image that is momentarily illuminated is visible. But it is instantaneously gone – replaced by the next image on the film, and so on. Our senses are analogous to the lit aperture, where the future passes it on its way to the past. The “real” world exits only during the time interval of the “present, and this is immeasurably short.
In summary: the past and the future don’t exist in the real world and the present is too short! So were Parmenides, Zeno and their cohorts right? Is it all some form of illusion?