On this date, the physicist and mathematician Albert Einstein was born at Ulm, in Württemberg, Germany. He is best known for his theory of relativity and specifically for the mass–energy equivalence, expressed by the equation:
E = mc2
Einstein’s many contributions to physics included papers on these ideas:
- The special theory of relativity (1905), which reconciled the laws of Newtonian mechanics with the laws of the electromagnetic field. This conflict was famously illustrated by the velocity addition problem. Einstein showed that the observed independence of the speed of light on the observer’s state of motion required fundamental changes to the notion of simultaneity. Consequences of this include the time-space frame of a moving body slowing down and contracting (in the direction of motion) relative to the frame of the observer. This paper also argued that the idea of a luminiferous aether – one of the leading theoretical entities in physics at the time – was superfluous.
- The first fluctuation dissipation theorem which explained Brownian (random) movement (1905). By explaining such movement as the consequence of molecular action, this paper supported the atomic theory.
- The photon theory and wave-particle duality (1905), derived from the thermodynamic properties of light. Einstein put forward the idea that certain experimental results, notably the photoelectric effect, could be simply understood from the postulate that light interacts with matter as discrete “packets” (quanta) of energy, an idea that had been introduced by Max Planck in 1900 as a purely mathematical manipulation and which seemed to contradict contemporary wave theories of light.
- The general theory of relativity (1916), a new theory of gravitation obeying the equivalence principle. The equivalence principle proper was introduced by Albert Einstein in 1907, when he observed that the acceleration of bodies towards the center of the Earth at a rate of 1g (g = 9.81 m/s2 being a standard reference of gravitational acceleration at the Earth’s surface) is equivalent to the acceleration of an inertially moving body that would be observed on a rocket in free space being accelerated at a rate of 1g.
The papers Einstein published in 1905 are the ones that history has come to call the Annus Mirabilis Papers. At the time, however, they were not noticed by most physicists as being important, and many of those who did notice them rejected them outright. Some of this work – such as the theory of light quanta – remained controversial for years. Einstein received the 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.”
Einstein’s views on religion have often been misunderstood, distorted, and sometimes deliberately fabricated to suit the personal convictions of the reporter. Einstein clarified his religious views in a letter (1954) he wrote in response to those who claimed that he worshiped a Judeo-Christian god (as quoted in Albert Einstein: The Human Side (1981) edited by Helen Dukas and Banesh Hoffman):
It was, of course, a lie what you read about my religious convictions, a lie which is being systematically repeated. I do not believe in a personal god and I have never denied this but have expressed it clearly. If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it.
In his book The World as I See It (1949), Einstein wrote:
A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms – it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man.
Einstein was also an advocate of humanism and a supporter of Ethical Culture. He served on the advisory board of the First Humanist Society of New York. For the seventy-fifth anniversary of the New York Society for Ethical Culture, he noted that the idea of Ethical Culture embodied his personal conception of what is most valuable and enduring in religious idealism. He observed, “Without ‘ethical culture’ there is no salvation for humanity.”
Einstein published a paper in Nature (vol. 146, pp. 605-607) in 1940 entitled “Science and Religion” in which he said that:
a person who is religiously enlightened appears to me to be one who has, to the best of his ability, liberated himself from the fetters of his selfish desires and is preoccupied with thoughts, feelings and aspirations to which he clings because of their super-personal value … regardless of whether any attempt is made to unite this content with a Divine Being, for otherwise it would not be possible to count Buddha and Spinoza as religious personalities. Accordingly a religious person is devout in the sense that he has no doubt of the significance of those super-personal objects and goals which neither require nor are capable of rational foundation … In this sense religion is the age-old endeavor of mankind to become clearly and completely conscious of these values and goals, and constantly to strengthen their effects…[Conflicts between science and religion] have all sprung from fatal errors…[E]ven though the realms of religion and science in themselves are clearly marked off from each other [there are] strong reciprocal relationships and dependencies … [S]cience without religion is lame, religion without science is blind … [A] legitimate conflict between science and religion cannot exist…[N]either the rule of human nor Divine Will exists as an independent cause of natural events. To be sure, the doctrine of a personal God interfering with natural events could never be refuted … by science, for [it] can always take refuge in those domains in which scientific knowledge has not yet been able to set foot.
In a letter to the philosopher Eric Gutkind on January 3, 1954, Einstein wrote:
…The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honorable, but still primitive legends which are nevertheless pretty childish. No interpretation no matter how subtle can (for me) change this. These subtilised interpretations are highly manifold according to their nature and have almost nothing to do with the original text.