The concept of mass seems to me to be quite confusing, indistinct, amorphous, ambiguous, and vague.
First of all, what is mass, exactly? By manipulating the F = MA formulation you find that mass boils down to "resistance to acceleration." But that is a circular notion with no independent meaning. It seems like a fictitious bookkeeping notion that is invented just to make things "balance." You need force and acceleration to give it any kind of meaning, but even then....I'll come back to this.
In terms of a less formal definition, it seems to me that "mass" boils down to inertia, as summarized in Newton's laws of mechanics. It is the TENDENCY of a material object at rest to remain at rest and the TENDENCY of that same object to remain moving, when moving, at the same speed in a straight line. This is just a different way of saying "resistance to acceleration," it seems.
But where does this "tendency" come from? What is it? Why is it?
Things get even more obscure and abstract when you consider that mass equals "energy." What is energy, exactly? The commonly accepted definition seems to be something like "the ability to do work." Putting the two together, then, we get:
The ability to do work is resistance to acceleration. Or maybe "inertia is the ability to do work."
What the hell does that mean? And these two things are deemed to be interchangeable, where either one can "transform" into the other. How does a tendency to remain stable and unchanging somehow get identified with "the ability to do work?" Sounds more like a lazy guy than an industrious one, know what I'm sayin? A guy who resists doing anything doesn't sound like a model for "the ability to do work." It sounds more like a guy who is essentially "incapable of doing work."
Things get all the more confusing when you talk about "potential energy." Potential ability to do work? The word "ability" is actually quite similar to "potential" to begin with, so isn't this rather redundant? Or is it essentially an oxymoron? It seems like you either have the ability to do work, or you don't. Are we talking about something analogous to a completely paralyzed guy who may someday regain the ability to move, or what? Like inertia, "potential energy" also strikes me as little more than a fiction invented to "make things balance."
Can anyone help clarify, and give some substance to, these various concepts for me? I'm not looking for an "explanation" that simply uses mathematical equations. Such equations implicitly assume that the kind of questions I'm asking have already been answered.
Edited by Moronium, 11 April 2019 - 04:34 AM.