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 Originally Posted by OngBonga
The reason for acceleration is forces. There's a fundamental difference between motion and acceleration. One is a constant and the other is a change.
Hmmm... so you're saying dr/dt is a constant (where r is the vector describing an objects instantaneous position)? ...because the universe doesn't hold r itself in any exclusive regard..?
Bold, yet controversial. I like it.
Not necessarily agreeing with it, but I like the train of thought.
Originally Posted by OngBonga
An inertial force is a fictitious force because it's emergent. It's not a real force, so I appreciate that in physics jargon, and what "force" means in physics, it's inaccurate. It's a fictitious force because it's not accelerating, it's the frame of reference that's accelerating, giving the illusion of acceleration, and therefore a force.
Hmmm... so you're putting it in the same category as centrifugal force?
Or you're saying centrifugal force is a type of inertial force, which are themselves "fictitious" forces..?
That's at least a consistent definition. I can jive with that.
Originally Posted by OngBonga
But what I was getting at is this... is that exactly what all forces are? An illusion? Take friction. What's happening on the Plank scale? I'd hazard a guess that particles move in a straight line at a constant speed in very curved space, giving the macro illusion of acceleration. So from the FoR of an individual particle, it's not experiencing acceleration, and therefore no force, and actually all that's happening is spacetime is locally more curved.
On the plank scale, it's all wave functions and energy levels.
Whether you put forces on a pedestal, or pressure, or acceleration, etc... whichever of those you hold as "fundamental" is fine, because at the end of the day, the relationships between those values is what it is. I.e. if particles exert point-like forces on each other, that's one thing. If the distortion of wave functions exerts a pressure on the wave functions it interacts with, that's a slightly different thing. But both describe the exact same physics, so which one you put on the "fundamental" pedestal isn't consequential.
Certainly, the mass of particles curves spacetime, but the relative strength of gravitation at that scale compared to the strengths of the Electromagnetic, Strong and Weak forces is tiny. It's there. It matters. But much less than the other 3 forces. Well, the Weak force isn't doing much, but it is there and still stronger than gravitational forces.
All that said... friction is one of the least understood things in physics. We can only measure it and report the measurements. We have no predictive model for what the coefficient of friction will be between 2 materials. We just have to do the experiment and measure it.
Originally Posted by OngBonga
Maybe. I'm just talking shit here but the concept of a "force" is ambiguous at the best of times, even in physics where you try to define it accurately. In basic language, it's something that causes an acceleration. But we then have to understand what acceleration means, and that's ambiguous too, especially at Plank scales where we don't actually know what's really happening.
Is it really that ambiguous? F = ma. That's a solid definition. We can measure m and r (again a position vector). If the vector r is not constant in time, then it changes, and we can calculate that change using calculus. v = dr/dt, with v the velocity and dr/dt the instantaneous rate of change in the position, defined in the limit as t goes to 0 s. Then if v is not constant, we can do that again, with a = dv/dt.
All of this is well defined for macroscopic objects to within the uncertainty of measuring position.
On the quantum scale, all of this is still true. It's just that now we're talking about the time evolution of a wave function and the movement of a probability function through space in time. But the fundamental laws of how to define velocity and acceleration are intact. We just have to rethink how we describe position. It's no longer exactly measurable, but a probability density function. We can't know the exact position, but we can calculate the expected values of position we may find when measuring it. The evolution of those expected values in time follows the same physics - v = dr/dt and a = dv/dt.
Originally Posted by OngBonga
So it might be that all forces are inertial forces and that term deserves more respect!
Dunno.
I'm personally opposed to the phrase "fictitious forces" because of what you mentioned. Those forces are NOT fictitious in non-inertial frames, and there's no reason the universe has to favor inertial frames just 'cause our puny human brains find them easier to work with.
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