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Details
ALBERT EINSTEIN (1879-1955)
Typed letter signed ('A. Einstein') to Sam Moskowitz, Institute for Advanced Study, Princeton, 4 April 1951, one word underlined by Einstein, one page, folio (slight staining and short tear to right margin), envelope; with a carbon copy of Moskowitz's letter to Einstein, 28 March 1951, a letter from Fred Hoyle to Moskowitz explaining Einstein's letter, and two related printed booklets.
THE VELOCITY OF LIGHT IN THE SPECIAL AND GENERAL THEORY OF RELATIVITY. Einstein's letter is in reply to a request from a science fiction writer to clarify 'a vital point in the writing of science fiction': it is understood that according to the special theory of relativity, no object may travel at more than the speed of light, but it has been suggested by [British astronomer] Fred Hoyle that this would be possible under the general theory of relativity. Einstein confirms that under the special theory 'the velocity of light relatively to an inertial system is something clearly defined and this speed of light is a limit for the speed of any object'. In the general theory, he explains, the picture is more complex: 'there is still the well-defined velocity of light with respect to a local coordinate system', but the theory does not allow for any 'privileged' coordinate systems 'so that it makes no sense in general to speak about the speed of light with respect to the coordinate system'; Einstein goes on to consider 'special cases where natural choice of the coordinate system exists' which would allow for discussion of the speed of light, which would however no longer be constant. (6)
Typed letter signed ('A. Einstein') to Sam Moskowitz, Institute for Advanced Study, Princeton, 4 April 1951, one word underlined by Einstein, one page, folio (slight staining and short tear to right margin), envelope; with a carbon copy of Moskowitz's letter to Einstein, 28 March 1951, a letter from Fred Hoyle to Moskowitz explaining Einstein's letter, and two related printed booklets.
THE VELOCITY OF LIGHT IN THE SPECIAL AND GENERAL THEORY OF RELATIVITY. Einstein's letter is in reply to a request from a science fiction writer to clarify 'a vital point in the writing of science fiction': it is understood that according to the special theory of relativity, no object may travel at more than the speed of light, but it has been suggested by [British astronomer] Fred Hoyle that this would be possible under the general theory of relativity. Einstein confirms that under the special theory 'the velocity of light relatively to an inertial system is something clearly defined and this speed of light is a limit for the speed of any object'. In the general theory, he explains, the picture is more complex: 'there is still the well-defined velocity of light with respect to a local coordinate system', but the theory does not allow for any 'privileged' coordinate systems 'so that it makes no sense in general to speak about the speed of light with respect to the coordinate system'; Einstein goes on to consider 'special cases where natural choice of the coordinate system exists' which would allow for discussion of the speed of light, which would however no longer be constant. (6)
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