34student

What I said is very well known and understood. I am surprised that you do not know that. True. But nonphysical entities do not cause anything physical to happen. They can't by their nature. How can a frame of reference have a physical effect on anything? The contraction simply exists with or without a frame of reference. The same goes for the noncontracted. They both just are as they are. Yes, that would be what GR demonstrates for us. But there are implications to that. One implication being that the matter in the square can not be in the same location as the matter in the rectangle, which tells us that there must be some kind of superposition in position. I know this. That is why I brought up the muon example. I do not know what you are contesting. I have said nothing wrong. Please tell me what I said that is wrong.

What do you mean when you say that there is only the one abstract distance? I hope someone on here corrects you. I did not say anything wrong there. If something is not physical, it is inert, not relevant, unobservable, not scientific, etc. Do both shapes exist?

I understand the basics of GR like variants and invariants. I will try to explain why I say that a frame of reference does not seem to matter or have any physical meaning. From what I understand, a muon has a half life that does not generally allow it to reach the Earth's surface from the upper atmosphere. But it blasts towards Earth so fast that length contraction actually brings the ground closer to it so that it reaches the surface of the Earth when it is not suppose to. For a person watching this muon hit the ground(if people could actually see them), there is no contraction. We know that what has happened and what will happen all exist eternally in GR. The muon is actually shaped as a worldline, a string if you will. This is the same for the human on the ground watching the muon come to Earth. And the human is shaped like a 4D snake if you will. So we have the string existing eternally and still, and we have the snake existing eternally and still. We can see that these two objects exist with or without a frame of reference or observer. The frame of reference never plays a part; it doesn't exist in a physical sense. Now GR says that the Earth is shaped like, say, an egg for the muon (approximately speaking), and the Earth has its spherical shape for the snake. But because we saw that a frame of reference does not actually exist in any physical way or have any physical meaning and therefor is irrelevant to the physical mechanics of the universe, we are left with the question of what shape the Earth actually is. Going back to my OP, how can we avoid some sort of superposition of position?

From what I understand about general relativity, it is correct.

I shouldn't have said block universe (even though it has everything to do with what I am talking about). Just replace "block universe" with "general relativity" in my last post to you.

The path of the frame of reference exists as a structure through time. There is no physical speed or movement of any sort in a block universe. Frame of reference has no physical meaning; it can not change anything. You said, "it depends on who does the measuring". It doesn't depend on who is measuring. What I was saying about frames of reference is very much relevant to this thread and to this conversation.

But what is a frame of reference anyways? In a block universe, how is it physically relevant? Observers do not physically exist in a block universe. And location is irrelevant. The block universe exists as it is with or without an observer and its location.

I put stress on "are". "Are" means exist. So the two lengths exist with particles at the ends of each. It seems to mean that at least one of the particles exists in two different positions. This is what I am asking in the OP.

So does measuring two different lengths (as you put it) mean that there are two different lengths? Yes, I know. So if there is a contraction for one observer and not a contraction for the other observer, then does that mean that there are two lengths?

But we know that there is a contraction from B to C, and we know that there is not a contraction from B to C. Is this is or is this not correct? Because for the purposes of my argument - in this case - length is an intrinsic property. Just like in my example about the equilateral triangle, the length is intrinsic.

But there can be a frame of reference in my argument. I am not saying there can't be. For example, from one observer's frame of reference, he sees particle C a meter from particle B. But from another frame of reference, particle C is 2 meters from particle B. Then, it would be true to say that particle C is 1 meter away from particle B, and it would be true to say that particle C is 2 meters away from particle B. Clearly that must be a superposition of position. How can there not be two different worldlines of a particle that exists, say 1 meter away from me, and that also exists 2 meters away from me (say from some other observer)?

A muon does not have to observe the length contraction of its surroundings for length contraction to happen. Observation shouldn't play a part in length contraction. Well that's kinetic energy, not length. We are talking about length, not kinetic energy. I gave an example of how length can be an intrinsic property of a structure.

It depends for what context. The length between points A and B in an equilateral tringle defined by points ABC is definitely an intrinsic property to the triangle. In the case of the change in length from length contraction, if we want to say that the contraction is real and not just an illusion, then there must be a change in distance that is intrinsic to the structure and shape of the universe.

To be honest I am more confused. I was really just referring to the superposition that a particle can be in when it is travelling in two different paths at the same time. Length contraction seems to demonstrate this too. Yes, but there is still a superposition in QM. I am trying to say that length contraction seems to imply a superposition also. Are you saying that length contraction depends on the observer? I don't think it does.

I am not saying that they overlap. I am saying that the particle must be in two different locations, like QM superposition. Sorry, I missed that. Definition of superposition from Marriam-Webster, "especially, physics : the combination of two distinct physical phenomena of the same type (such as spin or wavelength) so that they coexist as part of the same event. Schrödinger perversely suggested that until the box was opened and the outcome of the experiment observed, the particle must remain suspended in a superposition of two states: simultaneously going through both holes.— George Johnson" In our case the type of physical phenomena is location. I actually do not know. What is the difference?

Yes, the case that I meant to present was to have a length contraction between the 2 particles as observed by the 2 observers. If both distances between the 2 particles are correct, then at least one of the particles has 2 different locations. How is this not a superposition?

From what I understand about relativity, it seems as though the notion of superposition is unavoidable. Whether it be for particles and worldlines or just particles, my question is quite simple. If two different observers, travelling at different speeds relative to one another, are correct that two particles, at rest relative to one another, have different distances between each other, then how can this not be a superposition?

Oh cool. Thanks a lot for that. Interesting, thanks, that will help.

I know it isn't. I do not know what you are getting at. No, I only learnt that it was a t axis

Because of length contraction. For one observer a cubic structure is rectangular, for another it is a cube. The hypervolume of an object very much seems to depend on the observer. This is in contrast to what Markus Hanke says a few posts up.

Ok, but my point was that the 4d hypervolume does not seem to be the same for all observers.

Why not?

But how can that be? Clearly the 4d shape of the universe is different for a photon than for a human.

Hmmm, are you saying that the universe is a unique 4d structure? I never said that one particles has multiple world lines. My OP says "universe", not "particle".

Well, no, you said that I am learning and I agreed. What more do you want. As for your post, I am not sure what you are talking about. And you seem to contradict yourself (read in bold). I just don't know what you are getting at. 2) Spacetime is not the being, becoming or reality. It is a working model that has some characteristics the same as what we observe. We can use that model to extract predictions about (only) some what we observe and also to explain some observations that earlier theory failed to predict. 3) Spacetime has at least one characteristic not possessed by observations (reality ?) In order to have 'world lines' it's grid system imposes an orientation constraint, not inherent in the stucture of observational reality is models.