letter to then-President Roosevelt, warning him about the extreme danger of such a weapon in Nazi hands.
Though a pacifist who had never considered the idea of using nuclear physics for the sake of developing a weapon, Einstein was concerned about the Nazis possessing such a weapon. As such, he and Szilárd, along with other refugees such as Edward Teller and Eugene Wigner, “regarded it as their responsibility to alert Americans to the possibility that German scientists might win the race to build an atomic bomb, and to warn that Hitler would be more than willing to resort to such a weapon.”
According to historians Sarah J. Diehl and James Clay Moltz, the letter was “arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II”. In addition to the letter, Einstein used his connections with the Belgian Royal Family and the Belgian queen mother to get access with a personal envoy to the White House’s Oval Office, where he met with Roosevelt to discuss the danger personally.
As a result of Einstein’s letter and his meetings with Roosevelt, the U.S. initiated The Manhattan Project and mobilized all the necessary resources to research, build and test the atomic bomb. By 1945, this aspect of the arms race was won by the Allied Powers, as Germany had never succeeded in creating an atomic weapon of their own.
A thoroughgoing pacifist, Einstein would later come to deeply regret his involvement in the development of nuclear weapons. As he said to his friend, Linus Pauling, in 1954 (a year before his death): “I made one great mistake in my life—when I signed the letter to President Roosevelt recommending that atom bombs be made; but there was some justification—the danger that the Germans would make them.”
Theory of Relativity:
Though Einstein made many significant achievements over the years, and is widely known for his contribution to the establishment of The Manhattan Project, his most famous theory is that which is represented by the simple equation E=mc² (where E is energy, m is mass, and c is the speed of light). This theory would overturn centuries of scientific thinking and orthodoxies.
But of course, Einstein did not develop this theory in a vacuum, and the road that led him to conclude that time and space were relative to the observer was long and winding. Einstein’s eventual hypothesis of relativity was in large part an attempt to reconcile Newton’s laws of mechanics with the laws of electromagnetism (as characterized by Maxwell’s equations and the Lorentz force law).
For some time, scientists had been grappling with the inconsistencies between these two fields, which were also reflected in Newtonian physics. Whereas Isaac Newton had subscribed to the idea of an absolute space and time, he also adhered to Galileo’s principle of relativity – which states that: “any two observers moving at constant speed and direction with respect to one another will obtain the same results for all mechanical experiments.”
As of 1905, when Einstein published his seminal paper “On the Electrodynamics of Moving Bodies“, the working consensus among scientists held that light traveling through a moving medium would be dragged along by the medium. This, in turn, meant that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of that medium.
This theory also held that space was filled with a “luminiferous aether”, a hypothetical medium that was believed to be necessary for the propagation of light throughout the universe. In accordance, this aether would either be dragged by, or transported within, moving matter. However, this consensus resulted in numerous theoretical problems which by Einstein’s time, had remained unresolved.
For one, scientists had failed to find an absolute state of motion, which indicated that the relativity principle of motion (i.e. that only relative motion is observable, and there is no absolute standard of rest) was valid. Second, there was also the ongoing problem posed by “stellar abberation”