# Is space a property of something that moves and does it move with it? [closed]

While reading Sheng Liu (2015) A new approach to the correction of Galilean transformation IN Physics Essays 28(2) I started thinking that space itself moves with objects that have mass. So anything that is moving within that space frame of reference is moved without having a speed within that space framework. So a thing traveling at near c speed (lets say .75c) in a space framework that is also traveling at near c speed (lets say .75c), will then be travelling at close to twice the c speeds (1.5c) relative to a point outside of the space framework.

I think I am just misunderstanding some basic things, as I cant belive that things can move faster than c, and space itself dose not move, even if it bends.

My question: Is space a property of something that moves and does it move with it?

A compelling yes answer would make me so happy and revolutionize my understanding, but a no answer would reaffirm my beliefs, but please explain why.

• Quoting from the article OP mentioned: "From what has been discussed above, this paper argues that Lorentz transformation is invalid. Obviously, the special theory of relativity, which is based on Lorentz transformation, is also invalid." Simply put, in the fewest of words, this is crackpottery. Of course, I don't blame the OP, the article is published with the pretense of being genuine academic work. Voting to close. – Dvij D.C. Apr 19 at 6:34
• I don't think the questioner is trying to advocate the crackpot theory. Their underlying question "Is space a property of something that moves and does it move with it ?" is completely valid. After all, at one time the luminiferous aether was part of mainstream physics, until experimental evidence discredited that theory,. – gandalf61 Apr 19 at 6:52
• I agree that even if it is a crackpot theory, it can be useful to illuminate why this theory is crackpottery and what are the issues and faults in it. After all, that is the problem with most crackpot theories that pretend to be genuine. Most readers are not able to figure out why it is wrong, and hence often believe in it. It would be helpful to not close this question and rather have an answer that explains where it is wrong. The OP can alter the tone of the question to reflect this though – silverrahul Apr 19 at 7:15
• @gandalf61 Fair point, sorry for my poor judgment. Retracting my close vote. – Dvij D.C. Apr 19 at 7:34
• @DvijD.C.Thank you. No apology necessary ! The line between genuine curiosity and subtle promotion of a fringe theory is often not clear. – gandalf61 Apr 19 at 7:47

If spacetime curves, as GR tells us, then it must change. However, this change is not like the motion of a ball in space which moves from place to place and so it's relation to place changes, it changes instead in place. It's this change in place that the curvature tensor in GR measures. This change in place is like an atom of spacetime that flexes but does not change it's relation with other atoms of spacetime.

However, GR does not just tell us that spacetime curves, it can also shrink or expand. If spacetime is expanding, then two objects placed a metre apart will some time later be further apart. However, the two objects will not have changed place, which is the usual kind of motion and which is called inertial motion and to which I referred to above. The motion driven by the expansion of spacetime can be faster than $$c$$, the speed of light, whereas the usual inertial motion is limited by this speed.

Is space a property of something that moves and does it move with it?

By the above, it's the other way around. Objects move along with the movement of spacetime.

Moreover, spacetime is not 'a property of an object'.

No, space is not a property of something that moves.

You may have been misled by relativity textbooks which talk about reference frames as if they were part of some underlying physical reality. They are not. A reference frame is simply a way in which we can assign time and space co-ordinates to everything and every event in the universe.

In special relativity we often assign the origin of the reference frame to a particular object (let's call this A) at a particular point in time, and keep the origin of the three spatial co-ordinates fixed on this object. We can then measure distances and times of other events from that origin using light (or using measuring rods and clock that have been calibrated against light). But there is nothing special about A or the reference frame that we have "attached" to it - there are many, many other equally valid reference frames. And one of the two underlying assumptions or "postulates" of special relativity is that light has the same speed $$c$$ in every reference frame.

Another object B will define a different reference frame from A's. If B is stationary with respect to A then we can convert from the co-ordinates in A's reference frame to the co-ordinates in B's reference frame by just adding or subtracting a fixed amount from each of the three spatial co-ordinates. But if B is moving relative to A then we need some way of converting between co-ordinates in A's reference frame and co-ordinate's in B's reference frame. The constraints placed on this conversion or "transformation" are that the speed of light must be the same in all reference frames, and the laws of physics must not depend on which reference frame we happen to have chosen - because the reference frames are a useful convention for describing reality, but are not part of reality itself. Applying these constraints leads to the Lorentz transformation.

Special relativity replaced the earlier idea of the luminiferous aether, which was a like a reference frame, but was part of reality itself. Only objects that were stationary with respect to the aether would measure the speed of light as $$c$$ - other objects that were moving with respect to the aether would measure a different speed of light. But experiments that accurately measured the speed of light in the laboratory, such as the Michelson-Morley experiment, failed to detect any evidence that the Earth was moving through the aether. One attempt to patch up the luminiferous aether theory to accommodate these results was to assume that massive objects such as the Earth dragged some portion of the aether with them. But special relativity provided a much simpler and more consistent explanation of the experimental results, and did away completely with the need to have a privileged reference frame that was part of reality.

Special relativity and its extension in general relativity have been enormously successful in explaining many experimental results and observations about the universe on large scales (including gravitational waves, for example). Any alternative theory would have to be based on some very strong experimental evidence that SR and GR are incorrect, in the same way as SR and GR are based on experimental evidence that is inconsistent with previous theories. We do not have any such experimental evidence to discredit SR and GR or support any alternative.