General-relativistic Visualization General Relativity

I n our previous article about special-relativistic visualization,1 we described what the travelers from our highly developed civilization observed when they passed the Earth; now, they set out for the Cygnus X-1 binary system, which is roughly 6,000 light years away. The Cygnus X-1 system consists of a super giant variable star (HDE 226868) and a very compact object—presumably a black hole—with about 11 times the mass of our Sun.2 To make their journey as comfortable as possible, our travelers split their trip into two halves. In the first half, they accelerate with one Earth gravity (1 g), while in the second half, they decelerate again with 1 g. This simulates an artificial gravitation like on Earth. Fortunately, our travelers can take advantage of the special-relativistic time dilation effect, which makes the trip last only 17 years with respect to their ship’s chronometer. (Müller and his colleagues offer a detailed discussion of such a journey elsewhere.3) This time, the space ship captain will play it safe and order his crew to work out some tools in advance to simulate and explain any relativistic effects before they arrive at Cygnus X-1. The captain had heard rumors that a black hole devours all objects that come too close; in particular, the crew must find out how the curved spacetime around a black hole influences the propagation of light and the trajectories of massive objects. Again, we’ll take up their challenge, asking how we can visualize general relativity’s strange effects.