A Brief History Of Time

Einstein (1879-1955) is so widely considered one of the greatest minds of all time that his name has become synonymous with “genius.” Born in Germany, Einstein moved to Switzerland as a teen, where he got his PhD and where, in 1905, he presented his first four discoveries: that light can behave as a particle; that Brownian motion is caused by atoms bouncing off each other; that time slows down in objects traveling close to the speed of light (relativity), and that matter and energy are equivalent (E=mc^2).

These early discoveries overturned science’s belief in absolute time and in the separation of matter and energy. They also helped prove the then-new atomic theory of matter by using statistical methods, and they forced scientists to think about light as both a wave and a particle. Einstein’s work established Relativity and laid some of the foundation for quantum mechanics. In 1916, Einstein further revolutionized cosmology with his general theory of relativity that describes gravity, not as a force field, but as a warpage of space. He made many more contributions; in 1921, he received the Nobel Prize for those discoveries and especially for his photoelectric effect. In 1933, Einstein fled Nazi Germany, eventually settling in Princeton, New Jersey, where he worked at the newly formed Institute for Advanced Study.

From his and Planck’s work came Heisenberg’s uncertainty principle that launched quantum mechanics. Ironically, Einstein hated the direction quantum theory took—away from a knowable, predictable universe and toward a probabilistic, somewhat random one in which, as he put it, God must “play dice” to make things happen. He tried but failed to find ways out of quantum uncertainty; he also worked on a unified field theory that might reconcile gravity and the other three forces. 

Einstein’s work precedes that of Hawking, who made a great effort to develop a quantum mechanical interpretation of gravity that could meld Einstein’s Relativity theories into quantum physics.

British mathematician, astronomer, and physicist Sir Isaac Newton (1642-1727) developed the laws of motion and the theory of universal gravitation and published these theories in his book Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) in 1687. Though Einstein’s theory of general relativity has replaced Newton’s theories, Newton’s publications are considered some of the most important and foundational works in the history of modern science, and he is credited with being one of the primary influencers of the Enlightenment.

In addition to the foundational laws of motion, Newton also discovered that a prism refracts white light into its rainbow of colored components, thus proving that color is an intrinsic property of light. Understanding this led him to improve upon Kepler’s refracting telescope to make the reflecting telescope, which astronomers still use today. Newton also was one of the inventors of calculus, a branch of mathematics that is foundational to the entire discipline of physics. Calculus was also independently developed by another philosopher, a German named Gottfried Leibniz, who managed to publish his work first, though there is documented proof that Newton had developed the math prior to Leibniz’s publication.

Though Newton’s contributions to science are undeniable, Hawking does not shy away from acknowledging that Newton could be arrogant and unpleasant. Humanizing Newton emphasizes The Need for Humility in the Process of Scientific Discovery and helps to engage the reader in the personalities behind the scientific theories introduced in the book.

Aristotle (384-322 BCE) was an ancient Greek philosopher who helped found Western philosophy and science. He was a student of Plato and the tutor of Alexander the Great. Aristotle established ideas that, though some have been overturned, still form the basis of much current scientific and philosophical knowledge. In his book On the Heavens, published as far back as 340 BCE, Aristotle provided two well-reasoned arguments that the Earth is round, not flat. He also developed philosophies on the movement of the universe; scientific investigation; elements; and categorizations of plants, animals, and the sciences at large. Western science begins with Aristotle, so Hawking begins his discussion of modern theories of space and time with Aristotle’s views and discoveries of the ancient world. Though many of his ideas were found to be flawed as science advanced over the centuries, Aristotle provided a solid starting point from which later thinkers and scientists could build more accurate theories about the universe. 

Italian astronomer Galileo Galilei (1564-1642), often referred to by his first name, proved that the Earth isn’t the center of the universe but revolves around the sun along with the other planets. His proof—based on his own observations of the moons of Jupiter and the theory of a sun-centered realm proposed by an earlier astronomer, Copernicus—overturned thousands of years of beliefs, threatened the Catholic Church, and forced scientists to revamp their views of the cosmos. As such, Galileo is to early modern science what Einstein is to the modern quantum-relativistic view of reality. Galileo’s purpose in the book is to show how great advances in science often are met with indifference, derision, and threats.