Re: [Phys-L] treating force as a vector ... consistently

["LaMontagne, Bob" <RLAMONT@providence.edu>]

If the information travels at the speed of light, then aren't the "action" and "reaction" simultaneous in Space-Time?

Bob at PC
________________________________________
From: Phys-l <phys-l-bounces@www.phys-l.org> on behalf of Moses Fayngold <moshfarlan@yahoo.com>
Sent: Tuesday, August 30, 2016 10:48 AM
To: Moses Fayngold; Phys-L@Phys-L.org
Subject: Re: [Phys-L] treating force as a vector ... consistently

 <snip>
  I do not see the value of this axiom. As I said in one of my previous messages, "action-reaction" concept is most simple and fruitful only in classical and static situation, in which case the notion of their starting and ending together is meaningless. In more realistic situations involving dynamics this notion does not work or is, at best, not straightforward. Consider, for instance, an electron-positron pair production from collision of 2 neutral particles in the field of a distant proton. Each member of the newly-born pair immediately feels the field of the proton and experiences the corresponding action, but the proton will start feeling their field (and respective reaction) much later. So the axiom does not work for this system. It may work if we include the particles' interaction with each other's field as an intermediate agent, and the changes of the respective field momentum. But that would be no less complicated than the rocket-fuel-outgoing jet stream interactions in Scott's own example.
> > That last axiom means that the weight of a book can not be a force pair
> to the table's normal force. The book was interacting with the Earth long
> before it was placed on the table.

<snip>