This discussion focuses on computing the spatial trajectories of massive test particles in Schwarzschild spacetime, specifically how to generate (r, φ) pairs for realistic plotting. The initial approach involved numerical integration of the equation of motion (dr/dφ)² = f(r), which presented challenges such as determining the sign of dr/dφ and handling numerical errors. Alternative methods discussed include using elliptic functions for exact solutions and applying the geodesic equation in (t, x, y) coordinates for better numerical stability. Participants shared insights on implementing these strategies using tools like Maxima and Stormer-Verlet integration.
PREREQUISITESPhysicists, computational scientists, and anyone interested in general relativity and the dynamics of particles in curved spacetime.
Jimster41 said:I saw that but wasn't sure if that was for the orbit model code or just required boilerplate for distributing anything running Java.
Jimster41 said:Question about copyright.
I downloaded the source for this simulator from github. Is this code I can play with? I assumed some copyright, yours, by default. But then I've never heard of github, and got the idea it was considered open source. I'm pretty good with C#, and I code with it often (in application/algorithm contexts, not as a pure developer), but I'm pretty new(100%noob) to java. I made some changes and was having no luck saving them. I assumed because I am a doof with java. But then I thought I better check to be sure that I wasn't misunderstanding the copyright context (and my saves weren't working because it was locked).
Mentz114 said:Actually it is JavaScript, not Java. JavaScript can have objects see here for instance https://developer.mozilla.org/en-US/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript
I downloaded the zip file from github abd the code is working locally in FireFox. I'm still impressed.
Jimster41 said:I was able to run it no problem after the download. Just trying to figure out how to monkey around with the pieces. Thank s for the ref. I've got a good book and I'm pretty familiar with OO architecture, just not HTML, or CSS, or .JS. I've been working in a proprietary environment for... Too long. Its all drag and drop, with bits of custom C#. Lost my skillz.