| AS A STUDENT forced to flee Cambridge University during an epidemic in 1665–66, Isaac Newton—later knighted, becoming Sir Isaac—found a lot of time to do experiments. He put this time to good use, discovering the basis for many of the laws of physics he would go on to publish a few decades later. Newton’s equations accurately described acceleration and motion, and his universal law of gravitation explained in a concise and mathematical way gravity on Earth as well as in the solar system.
The physics of Newton dominated physics for more than 200 years. In Newton’s viewpoint, forces caused changes in motion, which could be precisely determined and calculated, and concepts such as space and time were absolute, the same for everyone. Physicists continued to accept this point of view until, in the 20th century, exceptions began to appear. With improved instruments and more imaginative theories, people began to probe objects and events that were not encountered in everyday life—tiny particles inside an atom, immense objects such as the entire universe, and small or large objects moving at exceptionally fast speeds. Laws described by Newton failed to hold true in many cases. New laws, and occasionally entirely new concepts, were needed. The new laws reduce to the old laws in familiar situations but increase their scope and accuracy. |
