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Wednesday 8 October 2014

Knowledge as construction III

Newton introduced the concept of gravitational force to explain the motion of the earth round the sun or that of the moon around the earth, though his gravitational force was not consistent with the concept of force as used by his contemporaries. If the western scientists were consistent they would not have accepted the gravitational force but that is not the way western science works or how theories (explanations) are constructed in that system of knowledge. As we have already said it was a “force” exerted by one body on another without any “physical contact” as such through a rope, pole or stick. It was not only action at a distance but instantaneous action. The moment a body (or particle) is “created” anywhere in the universe it exerted a force (gravitational) on any other body at any other place in the universe instantaneously. Later on in connection with Quantum action at a distance Einstein referred to such action as “spooky action at a distance”.

Almost all the so called educated people in the world or at least in Sri Lanka believe that there is a gravitational force as such though they cannot feel it with their sense organs. Gravitational force (or even gravitational field following Maxwell) is not sensory perceptible but the “educated people” have no inhibition in believing the existence of this force “without a rope” though they may not believe in God or the Natha Deviyo. There are at least a few people who claim to have “seen” the gods but nobody could claim that he/she has “seen” or “felt” the gravitational field. Of course one could claim that such seeing is illusion but in the case of the gravitational force nobody could say it is an illusion either as it is not to be seen by anybody.

Ernst Mach was against using non perceptible concepts in western Physics in order to “explain” perceptible phenomena and he objected to atoms, inertial frames etc., that could not be seen. Gravitational force also came under the category of concepts and the existence of gravitation was doubted from the beginning. When somebody says Newton discovered gravitation it implies that gravitation had been there from the very beginning and it was left to Newton to discover the force and not invent, construct or create it. The western scientists are supposed to discover existing phenomena and not construct.

However, in the case of gravitation, the question arises as to whether the phenomenon existed for Newton to discover it. Now let us consider what Newton knew when he “discovered” the gravitational force. Galileo had observed that near the earth bodies move towards it with the same constant acceleration. This was only a speculation though it is now called an observation. The so called experiments at Pizza in Italy were supposed to be conducted in a vacuum though even today it is not feasible to create a vacuum in open space. The leaning tower of Pizza was not in a closed room and it was impossible for Galileo to create a vacuum surrounding the tower in the seventeenth century. He neglected air resistance and in order to cover up his work he used objects of similar kind to drop from the tower and not dissimilar objects such as an apple and a feather. Had Galileo dropped an apple and a feather from the same height at the same time he would not have observed the two objects falling to the ground at the same time and he would not have been able to convince his colleagues that bodies fall with the same acceleration near the earth. Galileo was better in convincing others and he was a good marketer.  

Newton who was born a few months after Galileo died was aware of the “experiments” by the latter and was thinking of a reason to explain the observations of Galileo. Of course Newton was interested in extra terrestrial activities as well and wanted to explain the motion of the earth round the sun etc. It was then he had hit on the idea of a gravitational force which existed universally in the sense that any two objects (particles) in the universe exerted this force on each other irrespective of the colour, size, mass etc., of the objects.

However, Einstein had different ideas and he also did not believe in inertial frames of reference following Mach. The  Newtonian gravitational force was used in an inertial frame of reference and Einstein was interested in finding out what happened in other frames of reference. Einstein who was fond of thought experiments considered a western scientist in a rocket moving with let us say uniform acceleration in a frame of reference F. Let us call the frame of reference of the moving rocket frame R. Thus we have two frames of reference R and F, R moving with uniform acceleration in the frame of reference F.

Now suppose the scientist releases some object while the rocket is moving with uniform acceleration with respect to F. As the object is released it acquires the velocity of the scientist, and hence of the rocket at the time of release, with respect to F. However, the object does not acquire the acceleration of the rocket. This is observed when somebody jumps out of a moving bus, as he (usually a he and not she) jumps out he has acquired the velocity of the bus not the acceleration. 


In the frame F, the object begins to move with velocity of the rocket and will continue to move with the same constant velocity assuming that there are no forces acting on the object and that F is an inertial frame of reference, and Newton’s laws of motion are valid.. However, what does the western scientist in the rocket observe? We assume a pre SMS era and that the scientist does not know that he is moving in a rocket with uniform acceleration with respect to F. The scientist has no way of communicating with the external world and he is isolated doing “experiments”.

As far as the scientist is concerned he (again he as most of the western Physicists happen to be males) is at rest in R, which is his frame of reference, but the object he released though initially instantaneously at rest begins to move with uniform acceleration in the direction of his feet, in R, assuming of course that he is not standing on his head, since the object does not acquire the acceleration of the rocket.  

Now the Physicist, if he happens to be a theoretical person will start thinking why did the object move towards his feet with uniform acceleration. The observation is not different from that of Galileo but the latter had not given an explanation as to why it happened so. It was left to Newton to come out with an answer. Our friend in the rocket probably thinking like Newton would say the object moved with uniform acceleration towards his feet in R, as there was a big magnet or something similar outside the rocket that attracted the object. Now that is a reasonable explanation though he could have said look we are all moving with the rocket with the acceleration of the rocket but not the object and hence it moves in the direction opposite to the motion of the rocket. Who created the magnet that attracted the object?

Nalin De Silva