Sir, - I thank Prof S. Sen and Dr J. Sexton (April 30th) for their interest in my new theory. They refer to the many different proposed explanations (of the fact that light travels at different speeds around a spinning disc in opposite directions) listed in a 1993 paper. Prof Sen and Dr Sexton say that "all these explanations are completely successful in predicting the experimental results". That paper says: "This great variety (if not disparity) constitutes one of the several controversies that have been surrounding the Sagnac effect since the earliest days. Take two examples. Dieks and Nienhuis (1990) state that "seen from the rotating system, the two signals have equal speeds." That is incorrect; otherwise no difference would be measured. This error, like that of Prof Sen and Dr Sexton discussed earlier (April 2nd), is typical of the many futile attempts to explain the effect. A second example is the useless flying clock experiment (April 2nd), which is erroneously quoted as proof of the Sagnac effect, with which it has no connection whatever.
On a disc the diameter of the earth, the speed of a lazy snail (0.5mm per hour) would produce Sagnac's result, which is 4,000,000,000,000,000 times larger than the result forecast by Special Relativity. Prof Sen and Dr Sexton say that the two are in agreement. My paper has explained the effect, by showing that the light signal simply ignores the spin of the disc. While relativity has no place in trying to explain the effect, if the light ignores the movement of the disc, relativity theory is in trouble. Additionally, the speed of light has been measured as going faster westward than eastward - an anathema to Special Relativity Theory.
They say: "if we tamper with Einstein's theory . . . things fall apart; the centre cannot hold; mere anarchy is loosed upon the world." That is somewhat extreme. Perhaps the later lines of Yeats's poem are more apt: the worst are full of passionate intensity. Surely some revelation is at hand, Are we discussing a religion, or trying to explain the results of accurate scientific experiments? As this debate has become rather technical for newspaper columns, I am signing off and suggest that further discussion would be more appropriate in the Engineers Journal. - Yours, etc.,
Simmons Court,
Dublin 4.