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Simulation for Newton's gravity, GR to be added later.

  1. Jul 10, 2006 #1


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    May as well announce my Java applet that simulates Newton's law of gravitation. The initial conditions are set to give a demonstration of conservation of angular momentum. That is, 8 test masses are launched, all with the same angular momentum, and their orbits cross on the other side of the gravitating body.


    The above is written in Java. The source code is here:

    I'll eventually get around to adding other versions of gravity. I'd like to add GR with the usual Schwarzchild solution, and also with the flat space gauge gravity version developed at Cambridge.

    Unfortunately, my first effort at figuring out the force equation for gauge gravity has left me lost in a morass of algebra. The source paper I'm using is here:

    If someone can help with this, do comment. The equation used for Newton's gravity is quite simple, amounting to

    [tex]\frac{d\vec{v}}{dt} = \frac{\vec{r}}{r^3}[/tex]

  2. jcsd
  3. Jul 11, 2006 #2

    Your link to the source paper is blank
  4. Jul 11, 2006 #3


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    I just tested it and it's there. Furthermore, my DNS logs show that it has been downloaded in the past 24 hours by 2 people, one in England, the other in Indiana (and then myself to test it).

    A problem can arise if your browser doesn't know what to do with ".java" files. In this case, try (in Windows browser) right clicking, and then choosing "Save Target As". Another problem could arise because PhysicsForums abbreviates long links with "..." If you copy the link using text, you might get the "..." instead of that part of the hyperlink. To copy the correct hyperlink, right click and select "Copy Shortcut".

    I'm looking forward to seeing the difference between Schwarzschild gravity and the Cambridge gauge gravity. They should follow the same orbits, but the Schwarzschild version will get stuck on the event horizon while the Cambridge version will go on through to collide with the singularity. But I'm also sort of hoping that someone in that group will do the heavy lifting for me as I'm a particle guy, not particularly interested nor competent in gravity.

    But right now, all it shows is Newtonian gravity. But I think it is a pretty applet. I'll be adding a bunch of features to it as soon as I get some time. One thing I'd like is some buttons on the right side which set up various interesting initial conditions. That way the user doesn't have to sit there and figure out numbers to type in.

    I've only tested the applet on my own development system, and Windows Internet Explorer 6.0, if there are any difficulties in other browsers, I need to hear about it.

    Last edited: Jul 11, 2006
  5. Jul 12, 2011 #4
    The domain name has expired .. it no longer directs

    Owner: Carl Brannen (----@brannenworks.com)
    Registered: 2006-06-11
    Expire: 2011-06-11
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