Seeing things


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I sometimes suspect that I return to the same topics time and again. Not too often I hope, because that will put people off reading this blog (in case anyone does!) This is possibly a topic which I may have already addressed, but hopefully this post will be interesting anyway.

It seems obvious to me that we all see things differently, and I’m talking about vision here, not “seeing” as a philosophical point of view. Some are short sighted, some long sighted, and others have impaired vision. I see a colour as a shade of blue, while my wife sees it as a shade of green.

Toyota Celica 2.0 GT (ST202) shown in Bright T...
Toyota Celica 2.0 GT (ST202) shown in Bright Turquoise Pearl (colour code 756). (Photo credit: Wikipedia)

One could argue that the difference is merely where the line is drawn, but I think that it is more than that. Apart from the physical differences in the lenses of our our eyes, we may have differences in the physical structure of the rest of our eyes, perhaps in the rods and the cones, and it is highly likely that the physical structures of our brains are different, and our minds (which I think of as the software that runs of the hardware of the brain) are definitely different.

It’s no surprise then that my wife and I disagree on whether a colour is a shade of blue or of green. (Actually we disagree about a lot of things. I believe that it goes with being married for 40+ years!)

Plymouth Valiant 100 of some 40 years ago seen...
Plymouth Valiant 100 of some 40 years ago seen on street in New Orleans (Photo credit: Wikipedia)

In Googling around as I write this post I found an article about the brain’s colour processor. Interestingly it has a section entitled “Color is Personal” which is a part of my theme for this post. This section, however, is not really relevant to my theme as the author then discusses Achromatopsia, where damage to the colour processor causes all sensation of colour to disappear.

It seems that even in our own brains and thinking processes the idea of colour is not fixed. I read another article which describes our own personal perception of colours as “malleable”. The implication of this is that a person might describe a colour as “a shade of green” one day, and “a shade of blue” on another day. Is there no hope of a definitive answer?

Newton's color circle, showing the colors corr...
Newton’s color circle, showing the colors correlated with musical notes and symbols for the planets (Photo credit: Wikipedia)

A physicist could help us out, couldn’t he/she? He/she could measure the frequency of the light and say, definitively, that the colour is blue, or it is green, couldn’t he/she? Well, sort of. This would work for very simple colours, but real world colours are rarely made up of just one colour. The scientist’s scope would likely show a range of frequencies resembling a mountain range. That blue/green colour might have traces or red or violet, and is fairly certain to have more than one peak in the blue/green range.

Albert Einstein showed us that if a scientist was moving at a high speed relative to us, he/she would measure the frequencies in the colour differently from a scientist whose spectroscope was alongside us and not moving or moving at the same speed as us.

General Relativity
General Relativity (Photo credit: Wikipedia)

The ambient light has an effect on the colours that we perceive. A red object in red light doesn’t look red. Other objects of different colours look different in a red light. Similarly, it is difficult to determine the colours of cars and other objects under the yellow/orange sodium lights. According to Wikipedia, the colour of a street light has effects other than simple colour perception – it appears to affect peripheral vision.  New LED technology may be able to remove some of these deficiencies.

There are innumerable effects which affect or perception of colour. The most recently famous illusion is the dress which appears to people to be either black and blue or white and gold, but there are many such illusions. One which I came across a long time ago is the chessboard illusion. In this illusion, two square appear to be different colours, but are in fact the same colour. This illusion is usually shown in monochrome, but the illusion works in colour too, and depends on the shadow of the cylinder to produce the effect.


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One brain is very like any other brain. When a scientist shows someone a colour on a card, the same areas of the brain show activity in all individuals, if we exclude some cases where brain function is abnormal for some reason. We can’t delve very much deeper into this issue as we don’t know what this activity signifies, beyond the bare fact that the person was shown a card with a colour on it. We certainly can’t tell if they see it as a shade of blue or a shade of green, and we can’t tell what their subjective experience is when the brain activity occurs.

In some individuals a number or letter may invoke a sensation of colour. Such people might have the sensation of seeing something green when they think of or read the number 6. I don’t know if this imprinted behaviour because the person was presented with a green symbol when first learning their numbers or whether or not it was merely a chance association that arose at a different time, or indeed if it was because of some neurological happening or trauma that has allowed the association to happen.

English: A graph or how the brain interprets color
English: A graph or how the brain interprets color (Photo credit: Wikipedia)

Anyhow, when we see something, there are many stages to the process that  starts with light leaving the object, reaching our eyes, being refracted by the lens of the eye to form an image on the retina at the back of the eye, being sensed by the rods and cone cells in the retina, and sending signals to the brain, which then processes the data.

The amazing thing here is that the image sent to the brain is pretty messy. The eye is not a perfect sphere, the retina is curved in three dimensions and the resolution is pretty rubbish. The retina has at least one major gap in it, rods and cones are not evenly distributed across the retina. Our perception however, is smooth and break free. We have our image processing hardware and software in the brain to that for that.

Retinoblastoma retina scan before and after ch...
Retinoblastoma retina scan before and after chemotherapy (Photo credit: Wikipedia)

It means we can watch a soccer match, and we can see the black and white panels or the ball rotating as it spins across the television screen, when the unprocessed image that reaches our eyes may be quite blurred. Seeing is believing!


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Time and time again


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Well, this will be my third post in a row about time. I think I’ll discuss something else next week!

As I’ve said before, the path of a particle as it travels through space in the usual way can be represented as a line in a four-dimensional space-time system. There will be one and one line only that represents the history of the particle from the time it is created until the moment that it is annihilated. If we decide to plot only this particle’s location over time there will be no others lines in this space.

Diagram showing phase space plot of particle u...
Diagram showing phase space plot of particle undergoing betatron motion (Photo credit: Wikipedia)

The path will twist and turn as the particle is affected by fields and other particles. It may take a sudden turn when our particle collides with another particle. This interaction can be visualised by adding the data about the other particle to the same space-time graphs. However, since the particle is constantly jostled by other particles the diagram would quickly become crowded so to keep it simple let’s drop out the lines of all the other particles.

So we are back to the original single line we started out with. If we assume that it can’t time travel, there will be no loops and gaps in the line. In other words, for every time between its creation and destruction there will be one and only one set of three space coordinates. Of course the line will have curves and kinks as the particle interacts with other particles and fields.

English: The Markov chain for the drunkard's w...
English: The Markov chain for the drunkard’s walk (a type of random walk) on the real line starting at 0 with a range of two in both directions. (Photo credit: Wikipedia)

Suppose we allow choice into our system. Suppose we have two choices A and B. At the point that the choice is made (at a macro level), there are two possibilities for the space-time position of the particle. From that point on the particles history could be represented by an A line and a B line, which at first glance appears to contravene the single point rule. However by making a choice we are saying that either A will occur, OR B will occur, but not both, so we really have only one line.

A choice is not the same as travelling in time though, so let’s plot A AND B, and we will get a multiply branching tree of lines as the time line splits on every point where a choice is made.

English: Tree of choice for creative commons l...
English: Tree of choice for creative commons licenses. (Photo credit: Wikipedia)

The question arises as to which of these lines is the “real” life line of the particle. This we don’t know in advance because we don’t know what the choice will be, which leaves us in the uncomfortable situation of having something unpredictable happening and physics deals in things that can be predicted.

When a choice is made by someone, it is highly likely that one option is much more likely than the other. Maybe the probability is 0.8 to 0.2 (80:20 in percentage terms). Another way of looking at it is to say that, all other things being equal, if the choice were to come up 100 times, A would be chosen 80 times and B would be chosen 20 times. Of course in a 100 tests, it could be that the actual figures might be 79 and 21.

Brooklyn Museum - The Life Line - Winslow Homer
Brooklyn Museum – The Life Line – Winslow Homer (Photo credit: Wikipedia)

It would be highly unlikely that A would be chosen once and B chosen 99 times in 100 trials of course, but it remains possible. (We have to remember that the circumstances of the choice must be identical, that is, all other things being equal)

We could incorporate this into our system by adding a “probability” axis (running from 0 to 1, or equivalently to 0 to 100). A point on this axis would represent the probability of the choice that was made and the whole sheet represents the life of the particle.


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It appears that two points on the line are axis, the ones at 0.8 and 0.2 are “special”. In the stated situation those at two probabilities of the outcomes A and B. The probability of any other outcome say Z are zero and effectively outcome Z does not exist.

All things being equal there appears to be no physical reason why someone would choose one option over another. It may be that, all things being equal, that one option gets chosen more often than the other, but the sum of all the probabilities is one – in other words it is absolutely certain that one of the options is chosen. I find this totally mysterious. A choice is an event where the outcome is not dictated by the prior history of the event and is decided by the person making the choice.

English: Figure 1. Demonstration of the decisi...
English: Figure 1. Demonstration of the decision space (Photo credit: Wikipedia)

However the person’s mind is making the decision, and the person’s mind is equivalent to the state of his/her brain and the state of his/her brain is determined by physics, chemistry and biology. I see no “wriggle room” to allow for a person to make a choice.

Can we solve this dilemma by introspection? Descartes looked within himself and concluded that “I think therefore I am“. I don’t know if Descartes intended or realised it, but the implication is that thinking, which happens in the mind/brain, occurs before consciousness. In other words, consciousness is an epiphenomenon of the mind, just as the mind is an epiphenomenon of the brain.


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Why then do we think that we make choices and decide things? Well, by introspection I can look at any decision that I have made and I can always point at reasons why I made the choice. Well, of course this may be simple rationalisation. We look at the decision that we made we look at the reasons that might explain why we chose that course and we pick and choose the ones that we like.

While that may be the reasons that we give, and some of them may be true, I do believe that we have reasons for what we do, but those reasons are physical – the configuration of our brains, as a result of past events and happenings, results in a foregone conclusion – we perform an action which looks to the outside world like a decision.

Magnetic Resonance Imaging - Human brain side ...
Magnetic Resonance Imaging – Human brain side view. emphasizing corpus callosum. (Photo credit: Wikipedia)

For instance, if we are filling in a form and we are required to check a box, we “choose” the box depending completely on what has gone before. If the boxes are “Male” or “Female” we know what sex we are so naturally we would choose the correct box. No real decision is made. If we are annoyed at the form or we are in a joking mood we might tick the wrong box. It depends on our state of mind before making the decision what we do, and it depends only on that.

English: checkbox, check box, tickbox, tick bo...
English: checkbox, check box, tickbox, tick box Italiano: checkbox, check box, tickbox, tick box (Photo credit: Wikipedia)