SP2172 Project Progress Report

Finally! My SP2172 project, Spherical Orbits of Massive Particles Around a Kerr Black Hole, has shifted into a new phase. For the past few weeks, what we've been doing was reading up and learning what we could lay our hands on regarding Kerr black holes (black holes that rotate). But over the past few days, after putting the equations in a form that we want and verifying its results with other papers, we've finally moved on to generating data of our own.

General relativity, which replaces Newton's theory of gravity, predicts several peculiar features, one of which is a black hole. A black hole is essentially a lot of mass squeezed into an infinitesimal point, such that, according to general relativity, the gravitational potential is infinity at that point. More than predicting this strange feature, it has also given rise to counter-intuitive orbits, such as a particle that revolves around a Kerr black hole and yet has zero angular momentum.

Armed with the equations, we modified a C programme our staff mentor, Prof Edward Teo, provided us with. He used it to simulate spherical (i.e. constant radius) orbits of non-massive particles (i.e. photons), which had quite simpler equations (the equations for massive particles can span three lines across the page!).

The programme gives a chain of coordinates, with which we will use MatLab to plot into a 3D graph. Currently, most of the orbits fall into the expected types, which has the general shape of a ball of twine. I shall post snapshots of some of the orbits here once I get my hands onto them, or if possible, upload interactive Java applets of the 3D orbits (if we figure out how to do that).

Naturally, it is not these "twine" orbits that interests us. We'd be looking out for orbits that are not expected, and from there understand more about orbits around a Kerr Black Hole.

Best of all, this week is my most productive week of this semester so far. Those nights of working down to 3 a.m. has paid off.