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2 results

  • On Riemannian and Ricci curvatures of homogeneous Finsler manifolds

  • Part of
  • A. Tayebi
  • Journal:
    Canadian Mathematical Bulletin , First View
    Published online by Cambridge University Press:
    25 November 2024, pp. 1-18
    • Article
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  • The famous Cheng-Shen’s conjecture in Riemann-Finsler geometry claims that every n-dimensional closed W-quadratic Randers manifold is a Berwald manifold. In this paper, first we study the Riemann and Ricci curvatures of homogeneous Finsler manifolds and obtain some rigidity theorems. Then, by using this investigation, we construct a family of W-quadratic Randers metrics which are not R-quadratic nor strongly Ricci-quadratic.

  • Chapter 21 - Curvature and the Einstein Equation

  • from Part III - The Einstein Equation
  • James B. Hartle, University of California, Santa Barbara
  • Book:
    Gravity
    Published online:
    03 September 2021
    Print publication:
    24 June 2021, pp 445-470

  • Summary

    The relation between local spacetime curvature and matter energy density is given by the Einstein equation – it is the field equation of general relativity in the way that Maxwell’s equations are the field equations of electromagnetism. Maxwell’s equations relate the electromagnetic field to its sources – charges and currents. Einstein’s equation relates spacetime curvature to its source – the mass-energy of matter. This chapter gives a very brief introduction to the Einstein equation; we consider the equation in the absence of matter sources (the vacuum Einstein equation) and will include matter sources in Chapter 22. Even the vacuum Einstein equation has important implications. Just as the field of a static point charge and electromagnetic waves are solutions of the source-free Maxwell’s equations, the Schwarzschild geometry and gravitational waves are solutions of the vacuum Einstein equation.