2. When a force acts on a mass, acceleration is produced. The greater the mass of the object being accelerated, the greater the amount of force needed to accelerate the object. Click here to read more about Newton’s Second Law of Motion.
Others who followed Newton – most particularly Albert Einstein – refined our understanding of gravity. The most accurate description of gravity today can be found in Einstein’s general theory of relativity, which asserts that gravity is a consequence of the curvature of space-time.
Fascinated by Newton’s revelations about gravity? Check out this 15-minute video:
If Newton had only contributed his three Laws of Motion and his understanding of universal gravitation, we’d have remembered him as one of the world’s greatest scientists. But Newton didn’t stop there. He also built one of the first practical reflecting telescopes, contributed to the invention of calculus, and explored how white light can be broken up into a spectrum of colors by a prism, thereby laying the foundation for much of modern astronomy.
Yet Newton himself knew how much more remained to be discovered. He is known to have said:
I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.
By the way, in the past, you often saw Newton’s birthday as December 25, 1642. That is beginning to change, and now we are more and more often seeing Newton’s birthday as January 4, 1643. The difference is due to the fact that, when Newton was born, England was in the midst of a 150-year period of using a different calendar from the rest of Europe. The rest of the continent had already adopted the Gregorian calendar – same calendar we today use. However, the English were still using the Julian calendar, which lagged ten days behind because of a faulty method of accounting for leap years.
Bottom line: Isaac Newton was born on January 4, 1643 (December 25, 1642, in the same year that Galileo died, in the old style Gregorian calendar). His work laid much of the foundation for our modern understanding of the physical universe.