simulation explodes

gistfile1.txt

>>> physics.test()
[[[  0   0   0]
  [  0   0   0]
  [  0   0   0]]

 [[  0   0   0]
  [  0 100   0]
  [  0   0   0]]

 [[  0   0   0]
  [  0   0   0]
  [  0   0   0]]]
[[[   0    0    0]
  [   0 -300    0]
  [   0    0    0]]

 [[   0  200    0]
  [ 100  100  100]
  [   0  200    0]]

 [[   0    0    0]
  [   0 -300    0]
  [   0    0    0]]]
[[[    0   300     0]
  [ -700 -1000  -700]
  [    0   300     0]]

 [[  400  1100   400]
  [ -100   100  -100]
  [  400  1100   400]]

 [[    0   300     0]
  [ -700 -1000  -700]
  [    0   300     0]]]
[[[    0   900     0]
  [-2100 -2100 -2100]
  [    0   900     0]]

 [[ 1200  2700  1200]
  [ -600   100  -600]
  [ 1200  2700  1200]]

 [[    0   900     0]
  [-2100 -2100 -2100]
  [    0   900     0]]]
[[[    0  1800     0]
  [-4200 -3600 -4200]
  [    0  1800     0]]

 [[ 2400  5000  2400]
  [-1400   100 -1400]
  [ 2400  5000  2400]]

 [[    0  1800     0]
  [-4200 -3600 -4200]
  [    0  1800     0]]]
[[[    0  3000     0]
  [-7000 -5500 -7000]
  [    0  3000     0]]

 [[ 4000  8000  4000]
  [-2500   100 -2500]
  [ 4000  8000  4000]]

 [[    0  3000     0]
  [-7000 -5500 -7000]
  [    0  3000     0]]]
[[[     0   4500      0]
  [-10500  -7800 -10500]
  [     0   4500      0]]

 [[  6000  11700   6000]
  [ -3900    100  -3900]
  [  6000  11700   6000]]

 [[     0   4500      0]
  [-10500  -7800 -10500]
  [     0   4500      0]]]
[[[     0   6300      0]
  [-14700 -10500 -14700]
  [     0   6300      0]]

 [[  8400  16100   8400]
  [ -5600    100  -5600]
  [  8400  16100   8400]]

 [[     0   6300      0]
  [-14700 -10500 -14700]
  [     0   6300      0]]]
[[[     0   8400      0]
  [-19600 -13600 -19600]
  [     0   8400      0]]

 [[ 11200  21200  11200]
  [ -7600    100  -7600]
  [ 11200  21200  11200]]

 [[     0   8400      0]
  [-19600 -13600 -19600]
  [     0   8400      0]]]
[[[     0  10800      0]
  [-25200 -17100 -25200]
  [     0  10800      0]]

 [[ 14400  27000  14400]
  [ -9900    100  -9900]
  [ 14400  27000  14400]]

 [[     0  10800      0]
  [-25200 -17100 -25200]
  [     0  10800      0]]]
>>>