Physics: Inertia and . . . Spin.

[Arising_uk]

...

Forgive me if I'm interrupting a discussion of Zen quantum physics, or something.

Not me mate! I'm just trying to understand what socratus is getting at and I've not got anywhere yet. Physics is not my field hence I'm on a philosophy forum.

Boyhood physics has inertia as the amount of energy expended in moving something off-course? Or something like that.

Unless one is a physicist(and if one is then I'd assume they'd know what the hell is being said?), I doubt these conversations are of much use, as its just metaphysics based upon Physics otherwise.(and if anyone is wondering, yes, I know it could be said that there is a metaphysic behind science, unfortunately for the philosophers left behind it appears to work)

[Mike Strand]

Thanks, Arising_uk, for your candor. And I like your "boyhood physics" intuition about inertia. Close to my own, which is the amount of force needed to produce an acceleration, which is a change of direction and/or speed of motion. The greater the object's mass, the greater the force needed to produce a given acceleration. That's why I suggested to socratus that mass is a good stand-in for the concept of inertia, a concept that he seems concerned with.

By the way, I took just enough math and physics in college to be dangerous, but not profound.

socratus, have I made myself clear, here and in my earilier posts, as to why I took exception to your comments about Newton's law of motion in your first post? A short response, directly to this question, would be appreciated.

[Mike Strand]

Also, Cerveny appears to think inertia is a great mystery:

Inertia is as a great challenge and great test of physical theory’s consistence.

Well, when you think about it, gravity and mass are mysteries, too. But in practical terms, thinking of inertia as equivalent to mass, in Newton's laws we have what we need to build airplanes that fly and to send spacecraft to other planets.

Is this helpful, Cerveny?

[i blame blame]

OK, socratus and Arising_uk, I may be out of my league, you two getting away from classical Newtonian physics and into the subatomic and quantum realm. But I would still like a reaction to my earlier comments about what socratus wrote in his opening post, under 2. Newton b), as if Newton had actually said it:

But if I have only one, single body moving in the straight line
and it doesn’t interact with another body it means that this body
also must have an acceleration. In this situation I don’t know
how the acceleration appears, I don’t know if it is inner
acceleration of body, I know nothing about this acceleration.
But this kind of acceleration must exist and I will name it “inertia”.

I took exception to this, suggesting that an ordinary object can be moving (OK, relative to the earth's surface) with little or no force being applied -- that is, constant or zero velocity, no acceleration. I also suggested that inertia has to do with mass (m in the equation F=ma). From this equation we can see that a larger m (corresponding to greater inertia) would imply a smaller acceleration for a given force, or a greater force for a given acceleration. These agree with our intuition of inertia, a kind of "resistance" to acceleration.

If this is obvious classical physics (where relativistic effects can be ignored -- the physics we use to put men in orbit and land them on the moon), why did socratus say that a moving body must have acceleration? I think it's misleading, as is also, socratus, your way of attributing comments to famous scientists.

Forgive me if I'm interrupting a discussion of Zen quantum physics, or something.

If the velocity (including its direction) of a particle does not change with time (dv/dt = 0) with respect to an observer, then it has zero acceleration, because a:=dv/dt. This does not mean that there are no forces acting upon it. It could be a charged particle that's experiencing a force from an electrostatic field in one direction and an equal gravitational force in the opposite direction.

Also, Cerveny appears to think inertia is a great mystery:

Inertia is as a great challenge and great test of physical theory’s consistence.

Well, when you think about it, gravity and mass are mysteries, too. But in practical terms, thinking of inertia as equivalent to mass, in Newton's laws we have what we need to build airplanes that fly and to send spacecraft to other planets.

Is this helpful, Cerveny?

General relativity assumes that inertial and gravitational mass are equivalent. As it made some pretty accurate predictions, it seems that it's a pretty good assumption.

[Mike Strand]

Thanks, i.b.b., my understanding exactly. socratus? Cerveny?

[Cerveny]

Thanks, i.b.b., my understanding exactly. socratus? Cerveny?

I am not a beginner in physics. I am rather disappointed that I am not able to find here any new idea. All your statements I have already read :( There are perhaps some interesting questions here... I am not interested in physical phenomena, I know Most of them. I am interested about the essence of phenomena...
BTW: Why is not possible to "discover" proton/antiproton (as electron/positron) pairs by Dirac pattern..
There are too many problems (and nonsenses - singularities) in present physics.. Has a "time" geodetic (time axis) the end at the presence or is it going away...............................

[Mike Strand]

Thank you, Cerveny, for your clear reply, and I appreciate it! I, too, am mystified by the essence of gravity, mass, and the like. What is an electromagnetic wave, really? - for example. So I can understand better now the direction this topic has taken.

On the topic of the essence of the sub-atomic world and how we study it, I invite you to read my recent comments in another topic: Opinions on Physics -- Puzzles, mysteries, that sort .." It draws an analogy between rolling dice and the waveform of a particle like an electron.