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यह सिद्धान्त शताब्दियों तक चलता रहा । उससे भी अधिक सरलता आईस्तीन के प्रापेक्षवाद सिद्धान्त ने दी।
{The history of science provides many instances of situations such as we have been discussirg. To begin with the most obvious Ptolemy and his Arabian successors built up the famous system of cycles and epicyclcles wbich ena. bled them 10 predict the future positions of the planets.
Many, indeed felt that it was too complex to correspond to the ultimate facts. In the thirteenth century, Alphonso X of castille is reported to bave said that if the heavens were really like that, 'I could have given the Deity good advice, had He cousulted me at their creation. At a later date Copernicus also thought the Ptolemaic system too complex to be true and after yearəs of thought and labour, showed that the planetary motions could be deseribed much more simply if the background of the motions were changed. Ptolemy bas assumed a fixed earth; Comperuicus substiuted a fixed Sun. We now know that the Sun can no more be said to be at rest, in any absolute sense, than the earth; it is one of the thousands of millions of stars which together form the galactic system, and it moves round
the centre of this system just as the earth moves round the Shree Sudharmaswami Gyanbhandar-Umara, Surat www.umaragyanbhandar.com
