# Movement & Spacetime: Point A to B Difference

• matthewmussen
In summary, the difference between the idea of being at point A and moving toward B in space-time compared to being at point A and not moving and B not moving but the space-time between them moving and warping out of the way is that in the first scenario, the subject would experience actual movement from A to B, while in the second scenario, the subject would have the perception of not moving while the space-time between A and B shifts. This can be observed by external reference points, such as distant stars. Additionally, this theoretical concept challenges Einstein's Absolute Spacetime theory and changes the meaning of velocity.

#### matthewmussen

what would be the difference between the idea of being at point A and moving toward B in space-time; and being at point A and not moving and B not moving but the space-time between them moving and warping out of the way?

Didn't you just answer it yourself while asking the question? In the second case, space-time is curved. I assume that's not what you wanted to hear, since you said so yourself. What sort of answer are you looking for?

matthewmussen said:
what would be the difference between the idea of being at point A and moving toward B in space-time; and being at point A and not moving and B not moving but the space-time between them moving and warping out of the way?

The difference is that is scenario 1, the subject would have the epxreince of moving from A to B, whereas in scenario 2, the subject would ahve the experience of not moving while the two points would move to coincide.

It would be easy to tell the difference merely by observing external reference points, such as distant stars.

matthewmussen said:
what would be the difference between the idea of being at point A and moving toward B in space-time; and being at point A and not moving and B not moving but the space-time between them moving and warping out of the way?
Particles have wordlines in spacetime and cross events which are points. In a curved spacetime worldlines can cross even if at some point the lines were parallel to each other.

But spacetime itself is fixed, it does not change.

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Fredrik said:
Didn't you just answer it yourself while asking the question? In the second case, space-time is curved. I assume that's not what you wanted to hear, since you said so yourself. What sort of answer are you looking for?

would the idea change the way the motion, or lack thereof, of particles, is conceived; where as all particles are motionless, only space-time warps, muli-dimentionally. (i.e. - "my arm is not moving my fingers to my nose, but the amount of space time is curving or moving so there is less between them.) we would perceive in 3+1 dimensional space, as my arm is moving my fingers to my nose, using Einstein's perspective.

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DaveC426913 said:
The difference is that is scenario 1, the subject would have the epxreince of moving from A to B, whereas in scenario 2, the subject would ahve the experience of not moving while the two points would move to coincide.

It would be easy to tell the difference merely by observing external reference points, such as distant stars.

fredrik, thank you sir, but this idea is theoretical. visible external reference other than point A and point B (the sight of my fingers and the feel of my nose) are not applicable in this theoretical scenario.

MeJennifer said:
Particles have wordlines in spacetime and cross events which are points. In a curved spacetime worldlines can cross even if at some point the lines were parallel to each other.

But spacetime itself is fixed, it does not change.

Thank you MeJennifer, but your answer is based on part on Einstein's "Absolute Spacetime theory"in which this thread is written to challenge.

thanks to you all for helping

matthewmussen said:
would the idea change the way the motion, or lack thereof, of particles, is conceived;
I guess you can say that it changes the meaning of velocity. Consider e.g. the case of galaxies moving away from each other due to the expansion of the universe. I'm quoting myself from another thread:

Fredrik said:
When we say that galaxy A and galaxy B are moving apart with speed v, it really means that "the proper distance between A and B along the shortest possible path in the hypersurface of constant time coordinate changes by v units of length for each unit of time that we change the time coordinate".
This speed is something very different from the speed an object has in a local inertial frame. That's why it can be >c.

## 1. What is the concept of movement in relation to spacetime?

Movement in relation to spacetime refers to the change in position of an object over time, taking into account both the three dimensions of space and the dimension of time. This concept is often used in the theory of relativity to explain how objects move and interact with each other in the universe.

## 2. How does spacetime affect the movement of objects?

Spacetime affects the movement of objects by providing a framework in which the objects can move and interact. It is a four-dimensional fabric that is curved by the presence of mass and energy, and this curvature determines the path that objects will take as they move through it.

## 3. What is the difference between point A and point B in relation to movement and spacetime?

The difference between point A and point B in relation to movement and spacetime is the distance between them and the time it takes for an object to travel from one point to the other. This difference can be affected by factors such as the speed of the object and the curvature of spacetime.

## 4. How does the theory of relativity explain the concept of point A to B difference?

The theory of relativity explains the concept of point A to B difference by taking into account the effects of gravity and the curvature of spacetime. It states that the path an object takes from point A to point B will be affected by the gravitational pull of massive objects and the curvature of spacetime caused by their presence.

## 5. Can the concept of point A to B difference be applied to everyday life?

Yes, the concept of point A to B difference can be applied to everyday life. It is used in various fields such as navigation, transportation, and telecommunications to determine the most efficient routes and travel times between two points. It is also important in understanding the movement of celestial bodies and predicting their paths in the universe.