I'm trying to wrap my head around inertia/velocity, or just change in general, I guess. I'm unsure exactly sure were my gap is, or what question to ask, so I'll explain with a scenario.
Lets say I'm an insubstantial observer inside a flawless virtual simulation of our universe, watching two identical metal spheres floating in empty space. From my perspective, Sphere $A$ is moving at $1$ unit of velocity, directly away from my position. Sphere $B$ completely stationary, relative to my position.
I pause the simulation multiple times over a minute, record the positions of both, and from those measurements, I can say that the velocity of $A$ is $1$, and the velocity of $B$ is $0$.
1. What if I only paused once though, hadn't recorded anything before, and wanted to know where both spheres would be in the next frame (or shortest possible period of time, whatever that would be)? Is there an observable/measurable property of either sphere, or the space around it, other than a previous position, that would tell me that?
Edit: The consensus on #1 so far seems to be "no", so #2 is the only remaining unanswered question. Leaving this here for context.
2. If the answer is no, then why does sphere $A$ move at all? (To say the spheres simultaneously exist across all points in their eventual path is fine, but that's really just a different perspective of the same thing, so then, why are [$x,y,z$] for $t$ not equal to [$x,y,z$] for $t+1$, without looking at any previous point of $t$.)
Edit: This question was closed because the question needs clarity, and the answers so far seem to be answering a different question than the one I'm asking for #2, so I'll attempt to clarify "Why does sphere $A$ move at all?"
Lets say the invisible immortal Joe, every morning, without fail, moves a stone directly westward by $N$ inches, where $N$ is the number most recently spoken in proximity to the stone. Because Joe is flawlessly predictable, we can record the stone's positions for a couple days in a row to determine $N$, then know where that stone will be on any day until the next time a number is spoken.
- I know how we determine $N$.
- I understand that $N$ only changes when someone speaks the number in proximity to the stone.
- I understand that there are many ways of expressing the path of the stone and its current/future positions, both individually, and as an infinite set.
- What I want to know is why the hell the stone is mysteriously moving every morning. I don't know about Joe, or understand why he would want to push this rock around.
"We have no idea" and/or "we don't care" is a perfectly acceptable answer, if there's a reason not to care. I'm just assuming that this isn't the case, and the gap I'm perceiving is because something in this scenario IS actually the cause of the movement, and I'm missing it.