Commands to Adiabatically Increase the Mass

I generated this picture by

  1. setting View to ``Earth's Trajectory''
  2. Clear, Reset
  3. set Time to 10
  4. typing the following commands into the interpreter: 

    for {set JupiterMass 0} {$JupiterMass <= 100000} \
   {set JupiterMass [expr $JupiterMass + 1000]} {
  .clear invoke
  LASSPscale2_set .jM $JupiterMass
  .run invoke
}
  5. then hitting Run a few times to generate a picture.

When the transformation is adiabatic, it should be reversible. Try it backwards, starting from the finishing position of the last run: 

for {set JupiterMass 100000} {$JupiterMass >= 0} \
   {set JupiterMass [expr $JupiterMass - 1000]} {
  .clear invoke
  LASSPscale2_set .jM $JupiterMass
  .run invoke
}
Isn't it amazing! It comes back almost exactly to the original orbit! Hit Reset to bring back the original circle, and see that it agrees rather well. You might investigate whether the error is due to the non-adiabatic evolution (try incrementing by less than 1000 Earth masses at each time step) or due to the error in the integration (try Configure Algorithm Settings's Error Maximum to 1.e-9).

Jupiter:

How to Get Jupiter

Jupiter is available for Windows 95, Windows NT, Macintosh, and several Unix platforms (the IBM RS6000, Sun Sparc, Dec Alpha (courtesy Kamal Bhattacharya), Linux, and the PowerPC running AIX4.1). The files are available without charge by anonymous FTP (ftp.lassp.cornell.edu) or via the World Wide Web.
Last modified: May 19, 1996

James P. Sethna, sethna@lassp.cornell.edu.

Statistical Mechanics: Entropy, Order Parameters, and Complexity, now available at Oxford University Press (USA, Europe).