The human eye can only see a very, very small portion of all the light that is bouncing around in the universe. This is the so called "visible region" of the electromagnetic spectrum, which contains wavelengths from about 400 to 700 nanometers (1 nm = 10^-9 meters - For comparison, the whole electromagnetic spectrum ranges from wavelengths as small as 10^-12 meters to as large as 10^8 meters). It is hypothesized that these are the wavelengths evolution designed us to see because the sun emits radiation most intensely in this range, and thus light in this range is most available to us. There are actual physical explanations for why we cannot see light of higher and lower wavelengths than the visible range.
Amazingly, the reason we cannot see light of shorter wavelengths seems to be a strategic decision made by our optics to ensure that we do not "see things that are not there". This phenomenon is called "aliasing", and occurs when the brain mistakes short wavelengths for long wavelengths. Basically, the actual structures in our eyes that absorb light, the photoreceptors, are tiled across the retina on the back of our eyes, and can only be spaced so closely to one another. The spacing of our photoreceptors determines what's called the "Nyquist Limit", which marks the shortest wavelength that can be discerned. Wavelengths that are shorter than this limit will be confused with longer wavelengths (several very short wavelengths could fit inside one long wavelength, and thus the several very short wavelengths would be interpreted as one long wavelength). This would result in an inaccurate portrayal of the world. Fortunately, this does not actually happen, because other structures in our eye diffract light of short wavelengths and prevent them from even reaching our photoreceptors in the first place!
The reason we cannot see longer wavelengths is slightly more complicated, but has to do with the receptive field structure of our retinal ganglion cells, and will be explained more thoroughly in the "Origin of Optical Illusions" post.
Point: We only see a very tiny sample of reality.
is 'reality' only this very tiny amount of what we see, or is it more than that? if reality is more than that, then how are we supposed to know reality is real if we cannot experience it?
ReplyDeleteWhat I've come to realize is that there is no one reality. There are infinitely many levels of reality. This follows from the fact that there is no "absolute truth" (well in my opinion at least). My logic for this requires a lengthy explanation and I will be sure to make a post about it, but the point is, it is impossible for us to experience "reality" because there really isn't such a thing. However, this does not mean that what we are experiencing is not "real". It is simply a different level of "real".
ReplyDelete