History of Physics - E-book - ePub

The discipline of science that shades the most light on thestructure of the world and also the most advanced one isundoubtedly none other than Physics. Hence, it is muchneeded to have some basic ideas of not only what theup-to-date development of physics is but also how we came tothink in that way and how the whole of modern physics isattached with its history. In fact, the history of this science begins with Galileo, but inorder to understand his work it will be well to see what wasthought before his time.
The ancient scholars whose ideas weremainly taken from that of Aristotle used to believe that differentlaws for terrestrial bodies and that of celestial bodies persistedside by side at the same time. They even believed the sameholds true for living and dead matter as well. The four basicelements according to them were that of air, water, fire andearth - Among them the heaviest ones were the water andearth while air and fire were believed to be lighter. Earth and water had a natural downward motion, fire and airupward motion.
There was no idea of one set of laws fordifferent types of things or everything that matters; there wasno science of changes in the movements of bodies. Galileo andDescartes, in a bit lesser degree compared to Galileo -introduced the fundamental principles and concepts whichformed the foundation stone for physics until as long as thepresent century we are in. The ancient scholars worked hard to put forward the theorythat there exists one set of laws which holds true for living aswell as dead matter.
Among them, Galileo conceptualized twofundamental principles which actually made the discipline ofmathematical physics came into being: Law of parallelogramand that of inertia. This law of inertia is now known asNewton's first law of motion which is good enough to preciselycalculate the motion of different matter with respect to eachother, hence using the laws of dynamics. Technically, the principle of inertia puts forward the idea thatcausal laws of physics should be denoted in terms ofacceleration, i.e.
a change of velocity in amount or direction orboth which was found in Newton's law of gravitation. From thelaw of inertia, it is seen that the causal laws of dynamicsshould be differential equations of the second order, though thisform of statement could not be made until Leibnitz andNewton had developed the infinitesimal calculus. The work of majority of the students on the mathematical sideof physics can be explained with Newton's set of principles.
Thevery basic equations of motions or the ideas of dynamics andthat of inertia, momentum, mass and acceleration were appliedby Newton to large bodies like the Earth and the Moon forexplaining their structure and the universe's motion.