Chapter 2: Why it is like this ?

 

Let me start with the conclusion of chapter 1, that sensations and experiences of external objects are nothing but codes that our brain creates to identify distinct interactions that our bodies have with them.

Question to ask now is why our brains are obsessed only with the interactions that our bodies have with the external world.

We know from our knowledge of high school science that as a first layer of approximation, solid objects are a collection of molecules, tightly held together and defining the shape of the object. The air that we breathe-in is also a collection of molecules that are free to move about in free space while water that we see in the rivers and oceans are a collection of molecules that are partially bound together so that they can move freely on the surface of the earth, but not in free space.

We cannot see these molecules, but they are what constitutes the nature of external objects. Now assume for a minute that we could somehow see all these molecules wriggling in solids, flowing in liquids, and moving freely in air. We would see so many molecules around us (  molecules in a mole of a substance). Our brains would be overwhelmed with this huge amount of information. How difficult it will be in navigating through this vast mess of molecules. To process any navigation through this reality would be almost impossible for our brains of current size.

Instead of focusing on the molecular reality of the external objects, our brain focuses on how our bodies interact with these external objects. It is only interested in knowing whether interacting with the object adds value to our survival (if it is a food item then go towards it but if it is a predator, then go away from it) or will the object cause harm to our bodies (avoid a moving stone coming towards us).

Not only are our brains interested in understanding the quality of our interactions with external objects, but they are only interested in understanding the interactions that we have with relevant external objects. As an example, if a bacterium hits our skin (unlike a moving stone hitting our skin) and does not enter our bodies, then it is of no consequence to us in terms of our navigation or survival on the earth. Or take the case of infrared light falling into our eyes, which does not have any evolutionary advantage for humans. It categorises all such interactions as irrelevant and does not create any code to identify and store such information in our memories. We therefore don’t experience bacterium sitting on our skins or infrared images in our visual experience.

It will be an interesting digression to understand why our brains have evolved to create visual sensations (code) only for the visible spectrum of the EM wave.

EM waves getting reflected from external objects and falling into our eyes, originates inside the Sun of our solar system. Frequency of the EM spectrum that carries maximum radiation energy depends on the internal temperature of a star, as defined by Plank’s distribution^[3]. In the case of our Sun, the maximum energy is radiated in the yellow-green portion of the EM spectrum.

Notes:

[3] Planks distribution law for electromagnetic radiation is modelled on black body radiation and is given by the formula   

Additionally, while travelling through the empty space and before reaching the earth, most of x-ray and gamma ray components of the EM spectrum gets deflected by the magnetic field of the earth. Majority of the ultraviolet component of the travelling spectrum gets absorbed by the ozone layer of the earth’s atmosphere (however, there is still enough in the UV spectrum that escapes the ozone layer that is sufficient to cause skin cancer among a multitude of people). Hence, the EM wave falling on the surface of the earth is primarily the visible spectrum with maximum energy coming in at the yellow-green portion of that spectrum.

All objects on the surface of the earth deals primarily with the visible spectrum of the EM wave originating inside the Sun, absorbing some part of the spectrum, and reflecting others at its surface. Hence it makes sense for the evolutionary forces to deal only with the visible part of the EM spectrum.

Many animals like snakes have created additional methods to capture the infrared part of the EM wave. The infrared part is associated with heat produced in living bodies. Evolutionary forces have enabled snakes to create the visual sensation (code) for the infrared part of the EM spectrum for identifying and targeting living bodies emanating heat from their surfaces, for food. They are therefore able to capture the infrared part of the EM spectrum reaching the surface of the earth and getting reflected across objects. Snakes thus have a visual experience that includes the infrared frequencies.

An important fact to point out here is that different species have evolved different colour codes for the same frequency of the EM wave reaching their eyes. For example a dog sees a red rose in shades of brown^[4].

In this chapter we modify the conclusion of chapter 1, by stating that not only are sensations and experiences of external objects, codes that our brain creates to identify distinct interactions but also the interactions must be relevant for the brain to associate a code for them.

 

Notes:

[4] While humans have 3 cones in their eyes, dogs have two cones corresponding to yellow and blue colours. Thus shades of red and green probably looks like browns and grey scale.