The ramsey phase-change hypothesis |
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| Authors: | R A Lyttleton |
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| Institution: | (1) Institute of Astronomy, Cambridge, England;(2) Jet Propulsion Laboratory, Pasadena, Calif., USA |
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| Abstract: | The series of papers by the late W. H. Ramsey developing on a mathematical and physical basis the phase-change theory of the terrestrial core are summarised, and the numerous remarkable successes of the theory in accounting for hitherto unexplained properties of the interior of the Earth are emphasised. Subsequent attack on the problem by a different approach, based on established seismic data, confirmed independently the correctness of the general Ramsey-theory, and enabled it to be developed in numerical detail to demonstrate the precise nature of the evolution of the Earth. This treatment shows that through radioactive heating the Earth, starting in all-solid form, develops conditions at its centre suitable for the change of phase to take place, and there then occurs the sudden Ramsey-collapse involving formation within a matter of minutes of a metallic liquid core of  large radius (in fact of 2042 km radius and just over 6% of the mass of the Earth). With further increase of temperature at the core-mantle boundary, evolution proceeds continuously along a stable series of configurations of increasing core-mass and core-radius, anddecreasing overall surface-radius. A steadily decreasing moment-of-inertia accompanies the general contraction of the planet and at a rate in close agreement with that required by the intrinsic accelerative component of the angular velocity of the Earth revealed by the ancient-eclipse data. The total decrease of surface-radius since the initial sudden collapse has been by about 300 km, which involves a reduction of surface-area by some 50×106 km2, and a redistribution by means of folding and thrusting of about 160×109 km3 of outerlayers material, values quite adequate to account for some twenty separate periods of mountain-building during the age of the Earth. The iron-core hypothesis has nothing to offer by way of solution of any of these problems, and must be assigned negligible weight in comparison with the phase-change hypothesis.Paper dedicated to Professor Hannes Alfvén on the occasion of his 70th birthday, 30 May, 1978.That the density was between 5 and 6 times that of water was estimated by Newton from the relative masses of the planets, but he made no identification with iron.Principia, Book III, Propns VIII & X. |
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