That’s what einstein said. There is no fixed reference frame, but only relative ones. Every “inertial”(meaning, motion without any external force) frame of reference is equally valid as any other inertial frame movibg with respect to it.
But for sure we can tell earth’s orbit is not inertial since circular motion occur, which is due to external force of gravity.
Shouldn’t it be (at least theoretically) possible to find some sort of geometric center where - on average - the rest of the universe is expanding away from?
That could sort of explain why it’s inherently impossible to determine the center - but that doesn’t rule out the existence of a geometric center of the universe, right?
I’m not sure if I follow the balloon analogy. Sure, you can’t find the center on it’s surface. But somewhere within the balloon, there is a center. It might be virtually impossible to determine the center while actively inflating the balloon, but that doesn’t mean there isn’t any center? What makes the rest of the universe fundamentally different from an inflating balloon?
I’m genuinely curious.
That’s what einstein said. There is no fixed reference frame, but only relative ones. Every “inertial”(meaning, motion without any external force) frame of reference is equally valid as any other inertial frame movibg with respect to it.
But for sure we can tell earth’s orbit is not inertial since circular motion occur, which is due to external force of gravity.
Edit:typo
Shouldn’t it be (at least theoretically) possible to find some sort of geometric center where - on average - the rest of the universe is expanding away from?
Turns out, no; every point is expanding away from every other point, so every point sees itself as the center of expansion.
That could sort of explain why it’s inherently impossible to determine the center - but that doesn’t rule out the existence of a geometric center of the universe, right?
No, for the same reason you can’t find a point a balloon is expanding from on its surface. Everything is expanding everywhere.
I’m not sure if I follow the balloon analogy. Sure, you can’t find the center on it’s surface. But somewhere within the balloon, there is a center. It might be virtually impossible to determine the center while actively inflating the balloon, but that doesn’t mean there isn’t any center? What makes the rest of the universe fundamentally different from an inflating balloon? I’m genuinely curious.
It’s not, because the space itself is expanding