Is there such thing as rest mass.

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Discussion Overview

The discussion centers around the concept of rest mass, particularly in relation to the properties of particles such as spin and momentum. Participants explore the implications of these properties on the definition and understanding of rest mass, questioning whether the concept is meaningful or potentially outdated.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that the notion of rest mass may be nonsensical or a false convention, particularly in light of the introduction of spin as a property of particles.
  • Others argue that spin is a quantum concept that does not imply that particles are physically spinning, and that there exists a coordinate system in which a body can be considered at rest.
  • One participant suggests that if a particle has momentum or acceleration, then part of its mass could be attributed to its spin, raising questions about the definition of rest mass.
  • Another participant uses the example of an electron to illustrate that as it approaches the speed of light, its mass increases, suggesting that angular momentum and spin may also contribute to mass in a similar way.
  • There is uncertainty expressed by participants regarding their understanding of rest mass and the definitions involved, with one participant inviting corrections to their interpretations.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the meaning and implications of rest mass in relation to spin and momentum. Multiple competing views remain, with ongoing debate about the definitions and interpretations of these concepts.

Contextual Notes

Limitations in the discussion include potential misunderstandings of the terms "spin" and "rest," as well as the dependence on specific coordinate systems for defining rest. The relationship between mass, velocity, and angular momentum is also not fully resolved.

Simon43254
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Is there actually a superfluous reason for rest mass. I only ask because clearly as far as I know, all particles have spin, and I am led, (possibly falsly) to assume that so do things such as photons (although we know photons don't have rest mass anyway). Thus if "everything" has spin, (lets just leave this as nucleons for now) then it has an acceleration, and therefore isn't at rest at all even without it accelerating by definition. So is it therefore conceivable to suggest this notion of what we describe as rest mass is either nonsensicle or perhaps false convention if it existed as terminology before spin was introduced to our knowledge??
 
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I think you are misinterpreting "spin". That is a quantum physics concept that does NOT mean the particle is actually "spinning" like a top. You also seem to be misinterpreting "rest". There is always some coordinate system in which a body is at rest.
 
yes but what i mean is that spin refers to its angular momentum. Like how a gyroscope works. so clearly if it has any momentum or acceleration then it's total mass or atleast part of its mass can be said to be due to it's spin. So how can say a proton have a quoted rest mass if it's not strictly speaking at rest. Or is it my definition of at rest that is the problem?
 
Simon Malzard said:
so clearly if it has any momentum or acceleration then it's total mass or atleast part of its mass can be said to be due to it's spin.

Why do you say this?
 
The best way I can explain why I think this is by using an example. An electron has a finite, set, rest mass. Using Einsteins theory, as that electron approaches the speed of light, its mass increases. Thus a certain amount of its mass is due to the velocity it is traveling at. Now an object that has angular momentum, you can say has a tangential velocity, and therefore a centripetal acceleration, indicating that it's spin has contributed to if you like it's mass.

By the way, this was just a question, I don't know if I have any of this right or if I have gained a wrong definition of something along the way. If I'm going far out in the wrong direction please let me know where I am going wrong.
 

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