How Does One See And Hear Someone In An Instant
This article is an excerpt from a beautiful literary scientific writing of Dr Colin Blakemore, a British physiologists and head of the British Medical Research Council, someone I knew of. I would like to share it with you. It is called The Mind Machine.
This is a story of our perception of the world around us. To the inner eye and ear of the conscious mind, our sense gives us windows through which we see, hear, touch, taste and smell physical world. Dr Blakemore uses ‘Grandma’ here as the object perceived in this hypothetical story of a ‘photon’ [Einstein’s Quantum physics].
A single atom of gas, baking in the unimaginable heat at the surface of the Sun, suddenly shifts from one energy state to another, and spits out the surplus energy as a photon – the smallest, indivisible unit of light. This tiny pellet of energy is thrown into space at the highest speed that Einstein could conceive of. Eight minutes or so after its birth, our photon slows down a little as it hits the atmosphere of the earth and a faction of a second later it reaches the surface [of Earth]. It strikes the wrinkled skin of an old woman, but as chance has it, the wavelength of our charmed photon of light is such that it is not captured by the pigments of her skin. It is reflected, and 10 microseconds later it shoots into a tiny black hole, just 3 millimetres across. The hole is the pupil of a man’s eye.
The photon slips past the transparent window that covers the front of his eye [cornea], though the lens within it and on, between the particles of the gelatinous mass behind the lens [vitreous], even across the membranes and cytoplasm of nerve cells of the retina in the back of the eye. But time is running out. It penetrates a strange, thin cell at the back of the retina and its existence ends as it strikes a single molecule of pigment inside that cell, which captures the photon, destroying it by stealing its energy.
“Hello, Grandma.” The man whose retina has caught our hero, the photon, has recognised his grandmother. He sees her wrinkled face and her blue dress.
She smiles and opens her mouth. As she exhales, the folds of her larynx vibrate as the air rushes past them. Her breath rushes around her moving tongue as it darts skilfully back and fort within her mouth, occasionally touching her lips or her tongue. She is speaking. The rich mixture of tones and noises pulses through the air towards her grandson’s head.
Some of the vibrating particles in the air are caught by the crevices of his outer ears and funnelled into a narrow tube that leads to his eardrum. They beat on it, setting up a rhythm in a chain of minute bones, which rattle at another membrane, setting up waves in the liquid inside a tiny coiled tube. “Hello dear”. The man hears his grandmother speaking.
I’m sure the reader will appreciates how the human brain is organised for our perception of the world around us. For more than 2,000 years, philosophers and scientists have been puzzled by the apparent simplicity of perception, just like the grandson and his grandma seeing and talking to each other in a split second.
The great Greek geometer Euclid, the father of geometry, who lived 2,000 years ago thought that we see the world because light flows out of our eyes and that’s how we see the world around us. Plato who lived 100 years earlier realised that knowledge comes from within.
Aristotle, the first biologist, wrote that our sense organs receive the form of the object without its matter. These matterless qualities such as the colour or shape or smell without physical things in the world strike the sense organs and evoke the perception of the world.
Galileo’s telescope and Hubble’s telescope have done wonders to our perception of the universe. But these are only instruments with which we can see the world and things around, and the photons only bring light to us.
It is only the nerve cells in our brain that can create the knowledge of the world and the universe. It is the light sensitive nerve cells in our retina on which the photons strike, causing a visual perception of the ‘grandmother’ and her blue dress.
Our brain consists of nerve cells called neurones and there are 100 billion nerve cells in the brain. They process and transmit through the nervous system all the human perceptions and functions. Neurones exits in a number of different shapes and sizes and can be classified by their functions eg neurones in the Broca’s area in the left hemisphere of the brain are known for our speech production. When this area is damaged by a left-sided stroke, people have difficulties in speaking or can’t speak at all.
These neurones secrete a chemical called dopamine that sends messages or electrochemical signals for example, to the muscles. When these groups of nerve cells that produce dopamine are slowly destroyed, muscle movements become disorganised, and causes a disease called Parkinson’s disease.
When an excessive amount is secreted we have people with schizophrenia and doctors treat them with drugs to reduce its secretion. When young people are infatuated (excessive love) they have a huge surge of dopamine with a foolish and extravagant passion – the type who is likely to throw themselves off a cliff.
Our bodies run on electricity. Our heart beats with electricity. When the heart’ electric generator is not functioning, the heart stops beating and doctors put in a small electric generator called pace maker buried inside the body. One of my sister-in-laws had one.
All the information needed to recognise the ‘grandmother’ face, comes from the sensory perception by those tiny cells in the retina from the number of photons hitting them.
This short article is to give a vivid image of the wonders of science and how science works in our mortal body. What science does is to give us an account of the engineering machinery of nature, the evidence of which can be tested over and over again.