Non-arbitrary frame of reference for acceleration?

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Discussion Overview

The discussion revolves around the concept of frames of reference in relation to acceleration, particularly whether there exists a non-arbitrary frame of reference. Participants explore the implications of Noether's Theorem, the nature of fictitious forces, and the classification of inertial and non-inertial frames within Newtonian mechanics, special relativity (SR), and general relativity (GR).

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the lack of a corresponding reaction force for fictitious forces indicates a need for a non-arbitrary frame of reference for acceleration.
  • Another participant counters that there is not a single non-arbitrary frame but rather a class of inertial frames that are frequently discussed.
  • A different viewpoint posits that a 'master' frame of reference is necessary to express the acceleration of other frames, while also suggesting that this concept might extend to SR and GR.
  • Another participant disagrees, asserting that inertial frames do not contain non-inertial frames but are distinguishable from them, emphasizing that the distinction is not arbitrary.
  • A later reply dismisses the idea of a master frame as incorrect.

Areas of Agreement / Disagreement

Participants express competing views on the necessity of a master frame of reference, with some arguing for its existence and others rejecting this notion. The discussion remains unresolved regarding the implications for SR and GR.

Contextual Notes

Participants reference Noether's Theorem and the nature of fictitious forces, but the discussion does not resolve the implications of these concepts on the existence of a non-arbitrary frame of reference.

The Adversary
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The reason we can choose a frame of reference arbitrarily is that a physical system is not dependent on an absolute position, orientation or time.
According to Noether's Theorem, the invariance of a system under a change of position is equivalent to the momentum conservation law.
In the same way, invariance under a change in orientation is the angular momentum conservation law, and time invariance is the law of
conservation of energy.
In Newtonian Mechanics, momentum conservation is expressed as the action-reaction law; If for every force (change of momentum) there's an equal and opposite
reaction force, momentum is conserved.
For fictitious forces however, like the force that acts when the frame of reference itself is accelerating, there's no corresponding
reaction force; Hence there seems to be no conservation law in that case.
Does this not point in the direction of a non-arbitrary frame of reference for acceleration?
I've looked around on google, but I've always heard that this is an unsolved mystery in physics.

Any ideas?
 
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The Adversary said:
Does this not point in the direction of a non-arbitrary frame of reference for acceleration?
I've looked around on google, but I've always heard that this is an unsolved mystery in physics.
This is not an unsolved mystery. There is not a single non arbitrary frame, but rather a whole class of them. They are called inertial frames. They are discussed frequently.
 
You always end up with some kind of 'master' frame of reference that must contain all other frames of reference otherwise you can't express the acceleration
of a reference frame. And within a non-master reference frame, the acceleration of it acts as a fictitious force.
And if you include all of the fictitious forces, including the ones for rotation and accelerated rotation, your laws of physics always look the same
in all reference frames. I believe you can then call your laws generally invariant, even though that term is usually reserved for GR.
But it always requires a Master Frame!
I'm curious whether or not this Master Frame is also required in SR and GR; My gut tells me yes, but ...
 
The Adversary said:
You always end up with some kind of 'master' frame of reference that must contain all other frames of reference otherwise you can't express the acceleration
of a reference frame.
No, you don't. You end up with a set of 'master' frames called inertial frames. You can express the acceleration of a non inertial frame with respect to any of them completely equivalently.

Furthermore, inertial frames do not "contain" non inertial frames. They are simply physically distinguishable from non inertial frames. I.E. the distinction is not arbitrary.

The Adversary said:
But it always requires a Master Frame!
I'm curious whether or not this Master Frame is also required in SR and GR; My gut tells me yes, but ...
Your gut is wrong.
 
After deleting yet another post repeating the same misinformation, this thread is closed.
 

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