Is the word motion used in relativity?

[ostren]

I maintain that all physical motion is relative.

False. "Motion" is not a precise term... I would avoid using it if I were you.

So.. let me think the word "motion" is no good; it isn't found in any treatise about Relativity or in any Physics text -- 'that right, chroot??

 

[russ_watters]

All motion is relative, but not absolutely relative (I'm sure you'll get a kick out of that). All motion is measured relative to something else, but you can't just pick anything you want and change frames at any time you want. What you need to accept is that assuming an arbitrary gravity field gets switched on (materializes from nothing) at the instant a rocket fires its motor is not a reasonable thing to do. edit: thinking about it more, you'd need two gravity fields materializing out of nothing - one to counter the acceleration of the rocket that fired its motor and another that varies its strength/distance continually to provide constant acceleration for its companion flying in formation with it.

Same goes for the car turning that somehow manages to make the Earth accelerate with a small force.

In any case, I doubt warren will be real happy with a continuation of that convoluted discussion.

 

[R0man]

While it is true that the term "motion" may not be found in some texts on relativity or physics, it is still a valid term to use in understanding relative motion. The concept of relative motion refers to the movement of an object in relation to another object or reference frame. This means that the motion of an object can be described differently depending on the chosen reference frame.

For example, if we are on a train moving at a constant velocity, the other passengers and objects within the train appear to be stationary relative to us. However, to someone outside the train, these same objects appear to be moving at the same velocity as the train. This demonstrates how the perception of motion is relative to the chosen reference frame.

Furthermore, the theory of relativity, developed by Albert Einstein, explains that the laws of physics are the same for all observers regardless of their relative motion. This means that the laws of physics do not change based on the chosen reference frame, but rather the perception of motion may differ between observers.

In conclusion, while the term "motion" may not be found in some texts on relativity, it is still a valid term to use in understanding relative motion. The concept of relative motion is an important aspect of understanding the laws of physics and should not be dismissed as a misconception.