Part of a Series of Excerpts from Prof. Sundar Sarukkai’s Book, ‘What is Science?’

Dr. Sarukkai elaborates on the role of scientific models in theoretical work-

” Scientists spend an inordinate amount of time playing around with models and not with the phenomena of the world.”

(Page 38)

” Newton introduces the idea of modelling – of describing phenomena not exactly as they are but in terms of simplified pictures. Thus, we can talk of the motion around the sun by picturing the sun as a dot and the earth as another dot circling around the sun. In this model, the size and shape of the sun, the colour, heat and ‘smell’ of the sun are ignored. Instead, the massive sun and earth become points. Thus, the physics of motion becomes a problem of geometry. The basic assumption here is that a model mimics certain features of the phenomenon and the model is ‘as if’ the phenomenon is like it. This ‘as if’ feature of models has been the defining characteristic of theories after Newton.”

(Page 38)

” Not just physics, even chemistry is full of models. The atom is described analogously as a solar system with the nucleus (sun) at the centre and electrons (planets) revolving around it. Atoms are themselves modelled like small spheres. Molecules are shown as small balls attached with rods. The rods are the pictures of bonds that hold the atoms together. The model of a gas is that of molecules as small balls which bounce off each other. This is the billiard-ball model based on the analogy with the game of billiards. States of matter like solid or liquid are also modelled on similar lines. Across all levels of science, including biology, we see such simplified pictures of the more complex reality of nature. The famous gas laws, such as Boyle’s law, are called as ideal gas laws because they describe a gas as a collection of smooth round balls moving in a container. Science creates a picture of the world and this picture is not exactly like the world is but is merely a caricature, a cartoon. Atoms are not like how they are often pictured, bonds are not like rigid rods, molecules are not smooth round balls, but somehow this ‘as if’ description seems to work. This ‘as if’ description is necessary for science and is at the foundation of scientific theories.”

(Page 39)

He then touches upon how models are used to make predictions about natural phenomena-

” The other important activity which the theorist does is to calculate and compute. This activity is essential to science because it helps the scientists to eventually relate the model to the world. A striking example is Einstein general theory of relativity. At the end of some complicated mathematics, we have a simple, computed result that light will bend by some specific angle due to spacetime curvature. This result which is about a phenomenon in the world brings the theory back to the world. Most often, this is accomplished through the activities of calculation and computation, because these relate to what is ultimately measured. So we can see that what is special to scientific description is not merely using mathematics but using it to derive measurable quantities at the end.”

” This result oriented emphasis in all theories is what makes theories more than a story. In principle, for science, a theory is always under doubt and always opens to testing. So, although a theory is a narrative, a particular story, the demand placed on theory to match with observations makes it somewhat different from ‘pure’ fiction.”

(Page 41)
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