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In general relativity, a scalar field solution is an exact solution of the Einstein field equation in which the gravitational field is due entirely to the field energy and momentum of a scalar field. Such a field may or may not be ''massless'', and it may be taken to have ''minimal curvature coupling'', or some other choice, such as ''conformal coupling''. ==Mathematical definition== In general relativity, the geometric setting for physical phenomena is a Lorentzian manifold, which is physically interpreted as a curved spacetime, and which is mathematically specified by defining a metric tensor (or by defining a frame field). The curvature tensor of this manifold and associated quantities such as the Einstein tensor , are well-defined even in the absence of any physical theory, but in general relativity they acquire a physical interpretation as geometric manifestations of the gravitational field. In addition, we must specify a scalar field by giving a function . This function is required to satisfy two following conditions: # The function must satisfy the (curved spacetime) ''source-free'' wave equation , # The Einstein tensor must match the stress-energy tensor for the scalar field, which in the simplest case, a ''minimally coupled massless scalar field'', can be written . Both conditions follow from varying the Lagrangian density for the scalar field, which in the case of a minimally coupled massless scalar field is : Here, : gives the wave equation, while : gives the Einstein equation (in the case where the field energy of the scalar field is the only source of the gravitational field). 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Scalar field solution」の詳細全文を読む スポンサード リンク
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