Re: [Phys-l] Charged particles moving along parallel paths

[John Denker <jsd@av8n.com>]

On 12/05/2011 09:59 AM, Robert Cohen wrote:
> Would it be incorrect, misleading or otherwise inappropriate to say that
> the speed of light is finite and therefore the two charges don't "see"
> each other (i.e., the information from one charge cannot "reach" the
> other)?

Well, the speed of light *is* finite ... but this is a 
steady-state situation, so there is plennnnty of time 
for information to get from one place to another.

Furthermore, the essential part of the problem can (and
should) be understood locally, in a zero-sized region,
namely the nature of the electromagnetic field at the
location of the test-charge ... so we now have two
reasons why mentioning the speed of light would be
misleading.