Core formation by gravitational segregation allegedly released sufficient interior heat to melt the Earth. Analysis of the energetics, which compare gravitational potential energy （Ug） of a fictitious, homogeneous r...Core formation by gravitational segregation allegedly released sufficient interior heat to melt the Earth. Analysis of the energetics, which compare gravitational potential energy （Ug） of a fictitious, homogeneous reference state to Earth＇s current layered configuration, needs updating to correct errors and omissions, and to accommodate recent findings： （1） An erroneous positive sign was used for Ug while maintaining the reference value of 0 at infinity, which results in an incorrect sign fur AUg, which is crucial in determining whether a process is endothermic or exothermic. （2） The value of Ug for Earth＇s initial state is uncertain. （3） Recent meteorite evidence indicates that core formation began before the Earth was full-sized, which severely limits AUg. （4） Inhomogeneous accretion additionally reduced AUg. （5） The potentially large effect of differential rotation between the core and the mantle was not accounted for. （6） Entropy changes associated with creating order were neglected. Accordingly, we revise values of Ug, evaluate uncertainties, and show that AUg was converted substantially to eonfigurational energy （TAS）. These considerations limit the large sources of primordial heat to impacts and radioactivity. Although these processes may play a role in core formation, their energies are independent of gravitational segregation, which produces order and rotational energy, not internal heat. Instead, gravitational segregation promotes planetary cooling mainly because it segregates lithophilic radioactive elements upward, increasing surface heat flux while shortening the distance over which radiogenic heat diffuses outwards.展开更多
0 INTRODUCTION Among the rocky planets,only Earth remains active 4.5 Ga after formation.Moreover,only Earth has a chemically and structurally complex,bimodal surface with unequivocal horizontal motions.These unique pl...0 INTRODUCTION Among the rocky planets,only Earth remains active 4.5 Ga after formation.Moreover,only Earth has a chemically and structurally complex,bimodal surface with unequivocal horizontal motions.These unique plate motions are currently attributed to forces related to whole or upper mantle convection.展开更多
0 INTRODUCTION Crucial issues facing us are whether current practices prohibit today’s scientists from answering great questions,and how to sufficiently educate the greater population so that scientific methods and f...0 INTRODUCTION Crucial issues facing us are whether current practices prohibit today’s scientists from answering great questions,and how to sufficiently educate the greater population so that scientific methods and findings are understood.The most pressing challenges facing mankind include resource depletion.展开更多
文摘Core formation by gravitational segregation allegedly released sufficient interior heat to melt the Earth. Analysis of the energetics, which compare gravitational potential energy （Ug） of a fictitious, homogeneous reference state to Earth＇s current layered configuration, needs updating to correct errors and omissions, and to accommodate recent findings： （1） An erroneous positive sign was used for Ug while maintaining the reference value of 0 at infinity, which results in an incorrect sign fur AUg, which is crucial in determining whether a process is endothermic or exothermic. （2） The value of Ug for Earth＇s initial state is uncertain. （3） Recent meteorite evidence indicates that core formation began before the Earth was full-sized, which severely limits AUg. （4） Inhomogeneous accretion additionally reduced AUg. （5） The potentially large effect of differential rotation between the core and the mantle was not accounted for. （6） Entropy changes associated with creating order were neglected. Accordingly, we revise values of Ug, evaluate uncertainties, and show that AUg was converted substantially to eonfigurational energy （TAS）. These considerations limit the large sources of primordial heat to impacts and radioactivity. Although these processes may play a role in core formation, their energies are independent of gravitational segregation, which produces order and rotational energy, not internal heat. Instead, gravitational segregation promotes planetary cooling mainly because it segregates lithophilic radioactive elements upward, increasing surface heat flux while shortening the distance over which radiogenic heat diffuses outwards.
文摘0 INTRODUCTION Among the rocky planets,only Earth remains active 4.5 Ga after formation.Moreover,only Earth has a chemically and structurally complex,bimodal surface with unequivocal horizontal motions.These unique plate motions are currently attributed to forces related to whole or upper mantle convection.
文摘0 INTRODUCTION Crucial issues facing us are whether current practices prohibit today’s scientists from answering great questions,and how to sufficiently educate the greater population so that scientific methods and findings are understood.The most pressing challenges facing mankind include resource depletion.
