From times immemorial past man eyes used to wander around lots of twinkling lights in the universe and he that was proud master of the earth considered himself at the center of the vast universe controlling and affecting everything around him but the harsh reality came quite late.
Our magnificent eyes enable us to see only 0.001 percent of the stars in our galaxy on any clear day in the optimum condition and our galaxy is just one tens of millions of other galaxies. The proud was shattered and humans at least the physicists realized where we stand in the universe. How our study really started?
Although physics was subject of study of many philosophers in the past but modern physics started with the discovery of speed of light and journey of discovery was long one.
Light no wonder was imagined to travel at infinite speed in the past for human senses were no match to catch light in action. First time in 1676 Danish astronomer Ole Christensen Roemer discovered light traveled with infinite speed. Its while studying the moon of Jupiter Roemer realized that these moons disappear from time as they pass behind the gas giant Jupiter but these eclipse were not evenly spaced. It meant only one thing that the moons speed somehow fluctuated in the orbits but their was another explanation that suppose light has finite speed then there would be some delay in seeing the eclipse and if Jupiter moves closer to earth then delay will be less and if it moves farther then delay will be more. This explained everything and Roemer got the speed to be 140000 miles per second (Its really 186000) but still Roemer proved that light travels with fixed speed
Light was pretty much happy with its newly found quality speed but then entered grand master of the physics (Seriously students spend whole eleventh standard cursing him) Isaac Newton. Newton protested the concept of fixed speed because if you remember he said that speed is not absolute but relative quantity (Famous train example if you are sitting on the train then your speed with respect to you is zero and your speed with respect to person outside is speed of the train). Newton said that if nothing could have absolute speed how come light is special (Remember for Physicists everything is AAM Particle). People came forward to protect light and introduced concept of ether (No relation with Thor the dark world but like movie the concept also turned out to be crap). People said that whole universe is filled with some magical medium called ether and light has fixed speed in relation to that medium only. Fortunately for them people accepted that concept with fighting much. In 1887 Albert Michelson and Edward Morley proved through their experiments that ether is no more than figment of imagination. The experiment was simple (It now look as simple when we know the results) Michelson assumed that if earth is moving in the medium ether then if we observe the light coming from sun in different seasons then it must show some difference in speed (If we move towards the source then speed adds up and if we get away the speed diminishes) but the light was most stubborn character one could ever think of and adamant of becoming constant ‘C’ so Michelson received same speed of light in every season. Ether was removed from textbooks but Newton was gone and his theory was in grave danger. Then came superstar of the physics a man who continues to inspire mind and hairstyle of scientists’ world wide an unknown clerk who used to scribble physical theories for hobby Albert Einstein. Einstein saved Newton’s law saying that speed of light could be constant if we get rid of the absolute time as speed = Distance/Time so if light wants to travel different distance keeping the speed constant then time should vary from place to place and the concept that time is universal constant was wiped off. Time changes from place to place example when you are near sun (Imagine that don’t try this at home) the time would fly very slowly than when you are at earth or in space. Gravity effects time as well. Einstein by making time variable quantity solved the constant nature of light and light finally got the letter ‘C’ and value 299,792,458 meters per second.