Zur Ganggeschwindigkeit von Uhren auf der rotierenden Erde

On the Rates of Advance of Clocks on the Rotating Earth In 1905 ALBERT EINSTEIN came from his Special Theory of Relativity to the conclusion that a “balance clock” located at the earth's equator is somewhat slowed down compared with a clock resting at one of the earth's poles P (see Fig. 2 below). But interestingly, this retardation of time is fully compensated by an opposing gravitational effect which (according to the General Theory of Relativity, discovered later by EINSTEIN, 1908 - 1915) causes all (atomic) clocks even at any point A on earth's surface at normal sea-level at arbitrary latitudes φ to advance at the same rate as the clock at the pole: The kinematic time-dilatation of a clock A moving with the velocity v of the earth's daily revolution around its axis turns out to be precisely equal in magnitude to the acceleration of the advance of the same clock A with respect to the clock at P due to the gravitational potential-difference between A and P, resulting from the ellipsoidal figure of the rotating earth. These two variations in the clock-rates, amounting relatively to 1/2 (v/c)², where c denotes the velocity of light in vacuum, exactly cancel each other. Furthermore the so called clock-paradox and the Hafele-Keating-Experiment are rediscussed in a somewhat different way than usual.     

Die einwirkung der struktur auf die kristallisationskinetik des glasigen selens

By means of a calorimetric method the rate of crystallization of vitreous selenium samples remelted at various temperatures t_U (225–3502C) was studied at a temperature of 90.0°C. To describe the kinetics the Avrami equation was used. The samples remelted at t_U < 260°C crystallized in one stage, A. For the samples remelted at t_U ? 260°C two stages, A and B, were observed. The rate constants k_Kr = z(L · c_Kr)$\text{1}\text{2}$ and the coefficients z were calculated from the Avrami equation. For the samples remelted at t_U = 225, 250 and 330°C, the activation energy e_kr was determined.The values of z, k_Kr and z · E_Kr were found to decrease as the temperature t_U increased. The kinetics of crystallization probably depend upon the structure of vitreous selenium (i.e. on the number of crystalline regions and on content of the small rings), which in turn is dependent on the temperature _U. This supposition was confirmed mathematically.