Inertia at Subatomic Levels: Proton Quarks?

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Discussion Overview

The discussion revolves around the concept of inertia at subatomic levels, specifically in relation to protons and quarks. Participants explore the implications of force propagation in materials and how this might relate to the nature of inertia, particularly in the context of quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that a long metal bar cannot have its far end move instantly when pushed, as this would violate the speed of light, raising questions about inertia at subatomic levels.
  • Another participant clarifies that inertia is the resistance to changes in motion, distinct from the propagation delay of force through a material.
  • A different viewpoint introduces the concept of 'Born rigidity', speculating on its potential connection to inertia and suggesting that theoretical physicists may have explored this idea.
  • One participant discusses the propagation of pressure waves in materials, noting that such waves would experience loss and may not reach the far end of a long rod effectively.
  • Another participant corrects the initial assumption that force propagates at the speed of light, stating that it actually propagates at the speed of sound in the material.
  • One participant questions whether particles, if treated as having dimensions, would also be subject to similar propagation delays, raising the possibility of quantum mechanical implications.
  • Another participant asserts that particles are zero-dimensional points and lack spatial extension, challenging the notion of applying force to 'sides' of particles.
  • One participant agrees with the idea that pushing on atoms would result in a sequential response, although the timescale may be negligible for small distances.
  • Another participant emphasizes that propagation is not without loss, which could lead to no response at the far end of a long rod when struck or pushed.

Areas of Agreement / Disagreement

Participants express differing views on the nature of inertia and the implications of force propagation at both macroscopic and subatomic levels. There is no consensus on whether the discussed effects apply to subatomic particles or how they relate to inertia.

Contextual Notes

Participants highlight limitations in their assumptions regarding the propagation of forces and the nature of particles, indicating that the discussion is speculative and dependent on definitions of inertia and dimensionality.

BernieM
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I have a bar of metal 1 light second long and if i push it at one end it can not move at the other end until at least 1 second has passed because otherwise it would move faster than the speed of light. A .1 light second long bar .1 seconds later before the other end may move, and smaller and smaller and smaller etc., until finally we are the size of an atom. Does the same principle apply here? At subatomic levels such as a proton? Quark? Is this the cause of inertia or is it some other force that is manifesting itself?
 
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Inertia is resistance of any physical object to a change in its state of motion or rest. This is NOT the same effect as your example is giving. The reason that it takes time for the other end of the bar to move is that the force that you are applying to the bar on one end takes time to propagate through the bar to the other end.

Inertia means that it takes MORE force or work to move something heavy than it does to move something lighter.
 
BernieM said:
I have a bar of metal 1 light second long and if i push it at one end it can not move at the other end until at least 1 second has passed because otherwise it would move faster than the speed of light. A .1 light second long bar .1 seconds later before the other end may move, and smaller and smaller and smaller etc., until finally we are the size of an atom. Does the same principle apply here? At subatomic levels such as a proton? Quark? Is this the cause of inertia or is it some other force that is manifesting itself?

What you are referring to is a phenomenon that is called 'Born rigidity'. (Presumably Max Born was the first to discuss it thoroughly, so that later physicists started to name it after him.) An object that is in continuous acceleration is compressed in a way that has no classical counterpart.

It would not surprise me if in fact some theoretical physicist has explored an idea where inertia is linked with the tension that is accociated with Born rigidity.

For instance, check out the following discussion about http://www.mathpages.com/home/kmath422/kmath422.htm" . Of course, such musings are sheer speculation.
 
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Something else to keep in mind:

A pressure wave in a medium, during propagation, will effect loss.
This is usually presented by IR radiation as the medium molecules compress and decompress .
Thus, I highly doubt that a normal "shock wave" would even "get" to the end of such a long rod. As such, I doubt that the end of such rod would even move at all.

I would venture the same with considerations of a very slow moving pressure wave impact.
 
The speed of sound in most metals at room temperature is of the order of a few km/sec.

Any force you applied at one end would propagate along the rod at the speed of sound, not at the speed of light.
 
Perhaps I didn't state it quite right. Theoretically if i were able to push one end of a rod toward the other end, the other end could not move instantly because in doing so it would have violated the speed of light, so some time must pass before the other end may begin to move. On a subatomic scale, a particle (if it is not in a wave state), if it has 3 dimensions, would also be limited here, in that any force applied to 'one side' of the particle could not instantly make the other 'side' of the particle begin moving the same direction at that same exact instant ... or can it? Is this a quantum mechanical issue? I am not sure where to place this effect (if it even exists).
 
Particles don't have sides, they are zero-dimensional points, and lack spatial extension.
 
BernieM said:
Perhaps I didn't state it quite right. Theoretically if i were able to push one end of a rod toward the other end, the other end could not move instantly because in doing so it would have violated the speed of light, so some time must pass before the other end may begin to move. On a subatomic scale, a particle (if it is not in a wave state), if it has 3 dimensions, would also be limited here, in that any force applied to 'one side' of the particle could not instantly make the other 'side' of the particle begin moving the same direction at that same exact instant ... or can it? Is this a quantum mechanical issue? I am not sure where to place this effect (if it even exists).

I think you have the right idea. If you push on a couple of atoms, the one nearest to you would feel the force first followed by the others a short amount of time later. For this kind of distance the timescale is so small it's pretty much ignoreable. But for something like a 0.1 light year long bar it would definitely have an effect.
 
Let's not forget that the propagation is not without loss, expressed in the form of heat dissipation, which reduces the strength of the propagating wave.
As such, a very long rod, struck(or pushed) at one end, might have zero response on the far end.
 

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