Thread: Primacy of conservation laws View Single Post

## Primacy of conservation laws

Hello,

I am hoping for some input concerning shall we say the philosophy of mechanics, particularly with relation to the concept of force.

Most text books treat force as being something of a primary concept. A fundamental aspect of nature much like energy and mass and therefore something which cannot be readily defined, merely related to other concepts by rote application of Newton's laws.

To me it's not really. To me the conservation laws, and the quantities to which they refer, are the more sensible choice of foundation upon which to lay a conceptualisation of reality.

The explanation I have sketched out of force, then, is roughly as follows

- certain quantities are found by experiment to be conserved. For now, mass-energy, momentum and charge will do
- conserved quantities are really useful because we can think of them as being transferable, and transferable with quantifiable amounts and rates
- force is just a name for the rate of transfer of momentum
- "a" force is an influence upon the rate of transfer of momentum

To me this

- is simple
- makes Newton's laws seem like stating the obvious (2nd by definition, 1st=special case of 2nd, 3rd by definition as every transfer has a source and a sink)
- explains jet force in a way that is much more direct than appeal to Newton's 3rd, and reduces jet "force" to just a way of talking about straightforward momentum transfer
- is consistent with the standard model of particle physics and more broadly (by conservation of 4-momentum) with general relativity

To me the primacy of force is a long-obsolete hangover from the days when "contact force" was still considered a viable proposition. Recasting contact forces in terms of the Colomb interaction to me kind of forces the issue towards the above conceptualisation.

My only quibble is I'm kind of making this up as I go, wilfully ignorant of accepted views of the matter. I have not heard of such a conceptualisation clearly stated from any other source, although to me it seems implicit in the Standard Model -- or perhaps explicit, if you read the right books? But then again I've just picked up Feynman Lectures on Physics Vol 1, which includes a chapter on Characteristics of Force. Feynman -- who, of all people, you might expect to view force as nothing more than a transfer of momentum by gauge bosons or otherwise -- says nothing of the sort and just really seems to throw up his hands and say it's all too complicated(!)

So I guess I would like to know whether a) this view makes any sense and b) where are some good places to start reading about this approach as used by smarter people than me?

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