ASTR 1010 – Homework Assignment GR – Spring 2009

Question 1 – Tests of General Relativity:

1) Bending of light near massive objects. Light passing near a massive object will follow a curved trajectory.

2) Gravitational redshift – light coming from a massive object has its spectral lines shifted towards longer wavelengths. You can think of them as being “stretched” by the curvature of spacetime.

3) Gravitational lensing – light passing near a massive object will produce distorted images of the massive object.

4) Binary pulsars – two neutron stars in orbit about each other with their orbits decaying (i.e., they draw closer together) because of the emission of gravitational waves.

5) The existence of black holes – regions where the curvature of space-time is so great that even light cannot emerge from them.

6) Expansion of the Universe – a potential prediction that could have been made but was not…

Question 2 – The basic idea behind GR is that mass (actually mass density or energy density) curves spacetime and that curved spacetime tells matter how to move.