Independent photo perception

Light is believed to be a beam of superfast particles called photons travelling at about

300000000m/s (that’s 3x108m/s) in air or vacuum. Hence technically, the term photograph is used to

describe a graph recording the photon particles along with their wavelengths striking it. What is

colour then? It is wavelength, the difference between the crest and trough of the light waves. (Not

to deride students of Art who seek a higher meaning in colour). Yes light is also considered a wave. A

professor at the Indian Institute of Technology, Kharagpur, was once asked- is light a wave or beam

of particles? He said that “on Mondays Wednesdays and Fridays....light behaves like a wave, on the

remaining days like a beam of particles..... I think it that u kind of get my idea”.

Light of different wavelengths are perceived as different colours by us. Our eyes have a

photo sensitive layer called the retina......it contains rods and cones, types of cells that react

differently to different wavelengths of light and send signals via the optic nerve to the brain , to the

occipital lobe or visual cortex which is basically where we ‘see’. It is interesting to note that we have

light passing through any transparent material irrespective of its density......now whether light is a

wave or beam, it is one heck of an entity going through all that stuff.

Another interesting thing is that light is so fast that it travels in straight lines, but taking into

consideration the wave theory....it bends at corners .This is because the waves arms bypass the

obstacle leading to a minute but distinct passing of the light around an opaque object in its path. It’s

called the diffraction of light which was initially believed to go against the theory of Rectilinear

Propagation of Light, though the wave as such moves in a straight line.

Now that the basic reader is well acquainted with treating light as an entity and not just

something that comes from the sun, moon, lamps or other luminous objects (and I’m done with my

discourse on biology!) , I’ll come to my point of independent perception. Recently a sound clip

nicknamed the “teen buzz” (you can download it over the WWW) was passed around. Only a

teenager can hear this sound clip. I tried it and it actually works....your parents won’t be able to hear

it, though babies and most under 18s can. "This ain’t no magic". Normal human tympanic

membranes can perceive sounds from 20 to 20000 Hz as limits. But as we grow older, this range

continuously decreases and hence our hearing capacity changes. So the “buzz” is basically a very

high pitched note that adults cannot perceive.....or if they can it will be softer for them compared to

louder for a younger person. So it struck me that often I couldn’t make out the difference between

chrome yellow and lemon yellow ...but my art teacher could do so easily. Perhaps it is possible that

what is yellow ochre for me may be plain yellow for you.in the wildest of scenarios we may be all

seeing different colours and calling it red because that’s what we have been learning since

childhood. When we say that a colour is deeper than purple, perhaps it is just deeper than the

perception of purple that we have. This will lead to everybody accepting a common colour code

with the same index of wavelength or frequency differences. When we measure these on

computers we get definite values as we are actually testing the same colour, whether someone sees

it differently or not. If u see a green carpet and tell me that it is green, I will accept even if it is

actually being perceived as a red one by me. This is because I’m trained to consider that (the

frequency) red and name it as green. There would be no way to compare our perceptions and ideas

of light since we are talking of light on the same “scale” or “frequency index”. The difference

(frequency or wavelength) between any two colours as perceived by everyone remains the same

mathematically. This will lead to mutually agreed upon naming of wavelengths even though they are

perceived differently. It is to be remembered that light itself as an entity does not possess a property

called colour...but only wavelength and frequency and perhaps other chemical and physical props

that may determine its nature and are yet to be discovered.

When we say that an article is red, it means that the article absorbs all wavelengths of light

other than red which it reflects......and this strikes our retina causing us to perceive the object as red.

The previous para might just get you exploring your white matter, so here’s some "light-stuff". Since

light is a particle, it can strike other atoms and molecules changing their position, structure, or even

chemical orientation. The light reaction of photosynthesis occurs only in the presence of light

(photolysis......splitting of water or H2O; also, hydrogen reacts vigorously wit chlorine in the presence

of direct sunlight but mildly in indirect sunlight).So just perhaps, this striking of photons on our

retina is constantly changing the way we perceive light in our nervous system, and our brain is

magically adjusting its perception on the frequency scale dynamically all the time!!!

That’s all for this article. I’ll get something else soon.........:)

- Vedant Prusty

--taken from my Scientific blog, dated Mar-Apr, 2010.

{As such, this theory can neither be proved wrong, nor right. It was already mentioned that

there remains no way of comparing our perceptions. Do read up on “Qualia”

(http://en.wikipedia.org/wiki/Qualia) to delve more into this topic. I believe it’s a similar concept,

but not totally same as this one) }