Here is an article that I received from the About.hinduism.com  
  
http://hinduism.about.com/library/weekly/aa040100a.htm 
The article talks about the theory of karma & newton's principle of action & reaction.  I also got a similar article from Kamakoti.org too.  I am confused in connecting the law of karma to newton's principle on action & reaction.  Can anyone help me understand?  
  
Thank you.