dcbwhaley wrote:
What exactly do you mean by closed?
I have already indirectly answered this: "if an external force is applied to a system, then the system isn’t isolated; otherwise the momentum is conserved.", which for all intents and purposes reflects your description.
dcbwhaley wrote:
The standard answer to my question is to attribute momentum to the field, just the right amount to conserve the total momentum. Sounds like a fudge but to works.
Which is exactly what I did, except I bypassed the concept of the "field". Conserved!
dcbwhaley wrote:
Insomuch as classical momentum conservation is a purely mechanical concept whereas energy takes other non-mechanical forms I think that there is
Conservation applies in both cases, yes?
I had reduced my earlier question for brevity, but you took the reduced version literally by its word.
Let me reiterate the critical parts: " ... how does one fail where the other succeeds?" , or "the circumstances where momentum isn't conserved whilst energy is", or "Can you provide your description of the circumstances where momentum isn't conserved whilst energy is"
I want to see the justification for your original "
isn't".
Despite the rather advanced physics, nothing you have posted thus far suggests, let alone actually proves, that unequivocal statement.
Let's recap how this discussion developed, just in case perspective has been somehow lost:
- Where is the relevance to QM, fields and relativity within
your first mention of the issue?
- What exactly did you mean by "
and road junctions would be very interesting places"?
Where is the "interesting physics" in this?
- And what have these newly raised theories got to do with
cricket and snookerballs?
There was a strong implication that you disputed the momentum being conserved for those examples. If that wasn't the case, then what exactly was the point of raising them?
- And what of my unacknowledged rebuttal of your erroneous claim: "
no corresponding movement in the opposite direction" ?
- And why even pose your "
gedanken experiment" ? (which I fully addressed)
Why bring up those 100% "classical momentum conservation" examples when your answer supposedly lies wholly within the very non-classical?
I should repeat that the first mention of anything remotely relativistic, field-ish or QM-ish were subsequent to those 5 posts.
I have to say that those concepts are far too
bleeding-edge to support something that was originally and consistently portrayed (those 5 posts) as being so straightforward, wouldn't you agree?
So, what gives, Dave?