(from Advaita Musings)
Total Darkness. We are in Total Darkness. Or whatever passes for Darkness if we have never known Light. Out there there is no light, ie the sensations arising from brain excitation we describe as light, which our vision is constituted off. This is because the sensation of light as we see it does not exist in nature. It exists only as an effect of brain activity. Let us assume that there is a three dimensional world out there, with light sources reflecting off objects. The simple fact is light as you see it doesn't exist in nature, it is the effect of coded information exciting cells in the brain.
Take a computer game for instance. On the computer screen you see images. Open the computer case and try to peer into its memory circuits (if you can) and you will see nothing. If you see something it will be the switching on and off of electronic circuits, with no images in them.
The images you see on the screen are the result of interaction between the computer's display circuitry and the screen phosphors, the LEDs or LCDs of your monitor or phone/tablet display. Nothing you see on the screen exists within the computer itself. Whatever features you extract from the screen such as depth perception, movement, etc are unreal. Sight is just the same. What you see is your brains own internal decoding of electrical signals in your consciousness. The world you see simply does not exist in nature. They are forms of your own mind simply being triggered by electrical stimulation and are just as real as elements seen in a dream. In any case the continuity of the normal waking state could be the consequence of being in a dream you are unable to or are yet to wake up from.
Take the case of a telescope like an infra-red telescope or an X-ray telescope, such as the Hubble telescope. All the signals it picks up are invisible to the naked eye. There is no light or colour in the images it picks up. All it sees is pure blackness to the naked eye, and the information it picks up is translated into visible wavelength images on your computer screens.
The world outside your body is also in that condition. It is in total darkness, even with the sun shining at its brightest, with the birds and bees flitting around chirping and buzzing, the leaves fluttering and the branches of the trees swaying in the wind. All you see is the result of the coding of the signals the brain receives from the retina. The blues, reds, greens and yellows don't exist in nature. They exist, they come into existence only in your brain. In your senses.
Given that there is Total Darkness in the world outside, it is possible that there is also Total Silence, and total absence of Odor, Taste and Touch, the Total Absence of Depth Perception and the sense of Space or Distance arising in it? Is the latter also a possibility?
The only thing whose existence you can be truly be certain of is your condition of being aware.