Science In Daily Life

The Invisible Ether and Michelson Morley - The concept of the invisible ether or 'aether' is an old concept dating to the time of the ancient Greeks.  They considered the ether as that medium which permeated all of the universe and even believed the ether to be another element.  Along with Earth, Wind, Fire and Water Aristotle proposed that the ether should be treated as the fifth element or quintessence; this term which literally means 'fifth element' has even survived down to the present day to explain an exotic form of 'dark energy' which is crucial in some cosmological models.  These ideas spread throughout the world until the advent of a new springtime in scientific thought.  The first person in the modern era to conceive of the idea of an underlying ether to support the movement of light waves was seventeenth century dutch scientist Christiaan Huygens. Many others followed in expressing their opinions on the ether concept.  Whilst Isaac Newton disagreed w...

Special and General Principle of Relativity - By Albert Einstein  The basal principle, which was the pivot of all our previous considerations, was the special principle of relativity, i.e. the principle of the physical relativity of all uniform motion. Let as once more analyze its meaning carefully. It was at all times clear that, from the point of view of the idea it conveys to us, every motion must be considered only as a relative motion. Returning to the illustration we have frequently used of the embankment and the railway carriage, we can express the fact of the motion here taking place in the following two forms, both of which are equally justifiable : (a) The carriage is in motion relative to the embankment, (b) The embankment is in motion relative to the carriage. In (a) the embankment, in (b) the carriage, serves as the body of reference in our statement of the motion taking place. If it is simply a question of detecting or of describing the motion involved, it is in prin...