Question 3 The Schwarzschild metric is given by 2M 2M ds² -(₁-²M) di² + (1-²¹)- 1- dr² +r² (d0² + sin² 0 dó²). There are

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Question 3 The Schwarzschild Metric Is Given By 2m 2m Ds M Di 1 1 Dr R D0 Sin 0 Do There Are 1 (129.88 KiB) Viewed 48 times

Question 3 The Schwarzschild metric is given by 2M 2M ds² -(₁-²M) di² + (1-²¹)- 1- dr² +r² (d0² + sin² 0 dó²). There are Killing vectors associated with time invariance and angular momen- tum invariance in the direction in this geometry leading to the conserved quantities e = (1-2) and l= r² sin² 0 dr From this one can derive an analog to the radial energy equation in Newtonian mechanics by orienting the coordinates so that the orbits are confined to the equatorial plane where 0 = π/2 and u = 0. One finds 2 1 dr + Veff (r) = E 2 dr (e²_ -1) where E = and Veft(r) = - + 2/²/²2 - Mp³². Further, for circular orbits one can show that M | [₁ + √/₁−12 (+1)]. r+= | 2M Finally, for circular orbits of radius R do 1/2 M dt R³ (a) Which value of r corresponds to the Schwarzschild radius of stable circular orbits: r or r? Justify your answer. [3 marks] (b) Show that for circular orbits of radius R do 1/2 M -1/2 3M (²) ¹² (1-³) dT R³ R where is the proper time. [6 marks] (c) A free particle is moving in a circular orbit around a spherical source of curvature of mass M. The Schwarzschild radius of the orbit is 8M. Use the equivalence principle to argue that the period as measured at infinity should be larger than that measured by the particle. [4 marks] (d) Find the period of the orbit as measured by an observer at infinity. Find the period of the orbit as measured by the particle. [7 marks] M