TX_1~ABS:AT/ADD:TX_2~ABS:AT 34 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2021, 5 (1): 34-35 Review ARticle Sand Clock and The Concept of Time in Einstein’s Theory of Relativity Waria O. Amin* Cihan University-Erbil, Kurdistan Region, Iraq ABSTRACT The sand clock is a device used to measure time, consisting of two conical glass bulbs, which are connected vertically by a small opening neck. The top contains grains of fine dry sand. The upper part symbolizes the future, sand passes through the neck (which indicates present) to the lower part which turned past. In 1907, German scientist Hermann Minkowski (1864–1909) interpreted the concept of the four-dimensional space-time of Einstein’s theory in a two-dimensional cone diagram, in which the upper cone symbolizes the future, the neck the present, and the lower part the past. The researcher has noticed a great likeness, to the point of congruence between the shape and function of both, the sand clock and the diagram. This resemblance aroused speculations that Hermann Minkowski had been inspired by the sand hour in drawing his diagram. It cannot be attributed to a merely chance. Keywords: Sand clock, einstein’s theory, minkowski, time INTRODUCTION The sand clock is a device used to measure time, consisting of two conical glass bulbs, which are connected vertically to a small opening (the neck). The top contains grains of fine dry sand. The duration of the time scales is determined by factors that include the amount of material, its roughness, the size of the bulb, and the width of the neck. There are several accounts of who invented the sand clock. Some attribute it to the Pharaohs, some to the Palmyras, and Arab historians say that they were the ones who invented it.[1]. Images of the sand clock, as a symbol of time, have been found in art, and on tombstones and other monuments since ancient times in many parts of the world are a template for Microsoft Word versions 2010 or later, Figure 1. The upper part symbolizes the future, because sand will descend in the future, the sand passes through the neck (which symbolizes present), to the lower part and it turns into the past. EINSTEIN’S THEORY Einstein (1) published his theory of relativity (2) in 1905, but he did not finish it. He proposed the concept of a four-dimensional space-time.[2] In 1907, Hermann Minkowski (3) (1864–1909) contributed to the theory of his former student Albert Einstein, formulated in 1905. His most famous achievement was his development of the special theory of relativity. As a result of Minkowski’s contributions, relativity became geometrically possible to the theory of four-dimensional space-time, which is known as Minkowski’s space-time.[3] Minkowski explained the theory in a two-dimensional cone diagram in Figure 2: As indicated in the picture, the upper part symbolizes the future, the neck symbolizes the present tense, and the lower part symbolizes the past. COMPARISON By comparing the sand clock with the diagram, it becomes clear that: 1. Both symbolize time 2. Both consist of two conical symmetrical shapes connected vertically by a narrow neck 3. The upper part in both symbolizes the future 4. The lower part in both symbolizes the past 5. The neck in both symbolizes the present time Corresponding Author: Waria O. Amin, Cihan University-Erbil, Kurdistan Region, Iraq. E-mail: wariaamin@gmail.com Received: May 3, 2021 Accepted: June 14, 2021 Published: June 20, 2021 DOI: 10.24086/cuesj.v5n1y2021.34-35 Copyright © 2021 Waria O. Amin. This is an open-access article distributed under the Creative Commons Attribution License (CC BY-NC-ND 4.0). Cihan University-Erbil Scientific Journal (CUESJ) Amin: Time in Einstein’s Theory of Relativity 35 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2021, 5 (1): 34-35 It appears from the comparison that there is great match to the point of congruence between the shape and function of the sand clock and the graphic image of Minkowski. CONCLUSIONS The conclusion of this article shows that: 1. Hermann Minkowski quoted his diagrammatic idea in his interpretation of Einstein’s theory of relativity from the sand clock 2. The similarity between the sand clock shape and function, and the diagram reaches the point of congruence, which cannot be attributed to sheer coincidence. FOOTNOTES 1. Albert Einstein (1879-1955) was a German-born, Swiss, and American physicist. He is famous for the father of relativity theory, for being the author of special relativity and general relativity, which were the first building blocks of modern theoretical physics. 2. Relativity or the theory of relativity, one of the most famous theories of modern physics, which was developed by Albert Einstein at the beginning of the 20th century. There are two theories of relativity, the first is special relativity (1905) and the second is general relativity (1915). 3. Hermann Minkowski (1864–1909) is a German-born German mathematician and physicist, who worked as a professor of mathematics in Konigsberg, Zurich, and Gottingen. He developed number geometry and used engineering methods to solve problems in number theory, mathematical physics, and the theory of relativity. He is considered one of the founders of convex geometry. Minkowski’s most famous achievement was his development of the special theory of relativity in 1907AD, a theory that his former student Albert Einstein formulated in 1905. As a result of Minkowski’s contributions, relativity became geometrically possible to the theory of four-dimensional space-time, which is known as Minkowski’s space-time. REFERENCES 1. J. T. Anthony. Time and Measurement: Studies in the History of Horology and Fine Technology. New York: Ashgate Publishing Company, 1993. 2. A. Einstein. Relativity: The Special and General Theory (Translation 1920). New York: H. Holt and Company, 1916. 3. P. L. Galison. Minkowski’s Space Time: from visual thinking to the absolute world. Historical Studies in the Physical Sciences. Baltimore, Maryland: Johns Hopkins University Press, 1979. 4. J. Norton, Space-time. Einstein for Everyone, 2015. Available from: https://www.pitt.edu/~jdnorton/teaching/HPS_0410/ chapters/spacetime/index.html. [Last avccessed on 2015 Feb 09]. Figure 1: Minkowski diagrams. Source: Norton, 2015 Figure 2: Minkowski diagrams. Source: Norton, 2015