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    Einstein explains the difference between general and special theories of relativity

    Albert Einstein Typed Letter Signed

    "A. Einstein." One page, 8.5" x 11". Princeton, N.J.; July 10, 1952. Addressed to Dr. Waldron Gardiner, Einstein replies to Gardiner's letter of July 8 (retained carbon included), in regards to the General Theory of Relativity. Gardiner (d 1957), a pathologist in San Francisco, had sought further clarification on the theory and its "cosmological implications", writing in part: "There has been, I understand, some evidence that the remoter galaxies appear to be at an earlier stage in their life spans, as compared to the nearer ones. I cannot see how this fact can be reconciled with the fact that the present appearances to us of both groups must be considered as simultaneous."

    Einstein wrote the following reply in an attempt to explain the theory further, in response to Gardiner's inquiries:

    "Your difficulty stems from the fact that you do not distinguish between general and special theory of relativity, the latter being a limit case, where you neglect gravitation. In the latter case there are special coordinate systems (inertial systems) and with respect to such system the concept of simultaneity has a sharp meaning and can be defined empirically by light signals. In general relativity the space and time coordinates have no direct physical meaning so that also the concept of simultaneity of spatially distant events has no physical meaning. Physical meaning can be attributed to this concept only in certain special cases which are characterized by certain symmetry qualities. Such case is not realized in nature. But in those idealizations which we use to represent expanding space there are coordinate systems representing space-time in the mathematically simplest form. With respect to such coordinate systems simultaneity has meaning but the definition of simultaneity as defined in special relativity theory is out of place here."

    Albert Einstein (1879-1955) is one of the most famous individuals in the history of science due to his theory of relativity, considered, along with quantum physics, as one of the two pillars of modern physics. Einstein's theory upended Isaac Newton's long accepted hypothesis that space and time were fixed entities by demonstrating that neither were absolute. Einstein's theory, as the letter from Gardiner attests, was difficult for both laymen and scientists to grasp. Einstein's earliest ideas about his theory were first published in 1905 as his Special Theory of Relativity. His ideas, though, continued to develop, finally coalescing in his grand General Theory of Relativity, which was published in 1915. Einstein's theory of special relativity demonstrates that the laws of physics are the same for all non-accelerating observers, and showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels. The second component to Einstein's overall theory, that of general relativity, postulates that what we perceive as the force of gravity in fact arises from the curvature of space and time. Though the public could not understand the specifics of the theory, they did understand the important loss of certainty, which was summed up by the New York Times on December 7, 1919, "The foundations of all human thought have been undermined." However, when Einstein visited America for the first time in 1921, he asserted several times that most scientists should be able to understand it. Hundreds of books were published within a few years after the theory's publication to attempt explanations, including one by Einstein that contained thought experiments to help readers visualize his ideas. Nevertheless, opposition and confusion continued from some corners and was still prevalent almost forty years after the theory's 1915 publication, as evidenced by this letter.

    Although Einstein letters appear regularly in the market, those in which he specifically discusses aspects of his theory of relativity are rare. In the letter offered here - offered to the public for the first time - Einstein explains in detail the difference between general and special theories of relativity.

    Condition: Einstein's letter is lightly toned along outer margins, with usual flattened mail folds. A small area of soiling is present at top left corner. Signature is very clear. Accompanying letter is lightly toned throughout, with two holes at upper corner from a removed stable and an area of soiling where a paperclip left residue. Overall very good.

    Auction Info

    Auction Dates
    October, 2018
    25th Thursday
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