Non-arbitrary frame of reference for acceleration?

Click For Summary
A physical system's behavior is independent of absolute position, orientation, or time, allowing for arbitrary frame selection. Noether's Theorem links invariance in position, orientation, and time to conservation laws for momentum, angular momentum, and energy, respectively. While fictitious forces arise in accelerating frames, they do not negate the existence of inertial frames, which are essential for expressing acceleration. The discussion clarifies that there is no single "master" frame; instead, a set of inertial frames exists that can describe non-inertial frames without contradiction. Ultimately, the concept of a non-arbitrary frame of reference for acceleration is a misunderstanding, as inertial frames are sufficient for physical laws to remain consistent.
The Adversary
Messages
11
Reaction score
0
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?
 
Physics news on Phys.org
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.
 
For simple comparison, I think the same thought process can be followed as a block slides down a hill, - for block down hill, simple starting PE of mgh to final max KE 0.5mv^2 - comparing PE1 to max KE2 would result in finding the work friction did through the process. efficiency is just 100*KE2/PE1. If a mousetrap car travels along a flat surface, a starting PE of 0.5 k th^2 can be measured and maximum velocity of the car can also be measured. If energy efficiency is defined by...

Similar threads

  • · Replies 114 ·
4
Replies
114
Views
5K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 10 ·
Replies
10
Views
604
Replies
2
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 25 ·
Replies
25
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K