Rest Mass and Preferred Frame of Reference

[nsh3a94]

Einstein's theory of relativity is based on the fact that all motion is relative, which precludes the existence of a universally defined state of rest (priviledged reference frame). Einstein also recognises the existence of rest mass. If an object were at its rest mass, wouldn't it be perfectly stationary; in a universally defined state of rest?

 

[bcrowell]

If an object were at its rest mass, wouldn't it be perfectly stationary; in a universally defined state of rest?

Observers don't agree on whether an object is at its rest mass.

 

[HallsofIvy]

Every object, at any speed, is "at its rest mass" to an observer moving at the same speed.

 

[nsh3a94]

Observers don't agree on whether an object is at its rest mass.

Wouldn't all inertial reference frames that are observing the force of gravitational attraction between themselves and an object accelerating in a direction opposite to its absolute velocity vector will register a minimum force of attraction at the same time, which would signal the object having reached its rest mass?

 

[nsh3a94]

Every object, at any speed, is "at its rest mass" to an observer moving at the same speed.

Wouldn't this explanation deny the mass energy equivalence?

 

[harrylin]

Wouldn't this explanation deny the mass energy equivalence?

Certainly not. That "the mass of a body is a measure of its energy-content" relates first of all to the rest energy, see:

- http://www.fourmilab.ch/etexts/einstein/E_mc2/www/

Note about gravitational attraction: Everything was derived on the basis of the relativity principle, according to which no "absolute velocity vector" can be detected. The force of attraction is therefore not a function of speed in the way you perhaps think.

Harald