# Does length contraction imply a superposition of particles? [answered: no]

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2 hours ago, 34student said:

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.

There's only the one Distance, but different frames of reference will find it has different values.

I've found easier to think in terms of it being a variable, rather than always having the single value we are used to.

We're fairly accustomed to seeing this same sort of thing in fractions though.

ie. 1/2 = x/y

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8 hours ago, 34student said:

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?

Just as there are different kinetic energies; it depends on who does the measuring. Length, like kinetic energy, is a relative quantity.

7 hours ago, 34student said:

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

Two measurements by two different observers does not mean anything is in two positions at once, just as it doesn’t have two speeds at once. A superposition is measured by a single observer.

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10 hours ago, 34student said:

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?

Yes, there are two lengths, if you like. The point about relativity, which you seem not to have absorbed, is that measurements of length (and time) are not absolute. There is no single "true" value for them. Any measurement of them depends on the viewpoint (frame of reference) from which they are measured and all are equally "true". If you still can't grasp this I suggest going back to your books and reading carefully what relativity says.

Nothing can inhabit two different reference frames at once. So you can't do QM (for example) from the viewpoint of two different reference frames at once either.  Which means that relativity does not lead to a superposition of states, as you originally suggested.

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7 hours ago, exchemist said:

Yes, there are two lengths, if you like.

Do you not think this statement gives the wrong impression ?

Here is a story

There is a long straight road through the middle of my village where the speed limit is the standard 30mph.
However so many drivrs fail to observe the speed limit that the local neighbourhood watch has set up a speedwatch.
They have two identical portable radar guns and their procedure is to calibrate or synchronise the guns by observing Jeff driving through the village, whilst standing together at the roadside.
Having agreed that both guns give the same reading, Jim gets in the car with Jeff who follows behind a driver driving through the village.
Jack stays by the roadside and reads the speed of the driver on his gun as a steady 40mph.
In Jeff's car, Jim reads a different steady speed of 10mph on his gun.

So does the errant driver have two speeds ?

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11 hours ago, Endy0816 said:

There's only the one Distance, but different frames of reference will find it has different values.

I've found easier to think in terms of it being a variable, rather than always having the single value we are used to.

We're fairly accustomed to seeing this same sort of thing in fractions though.

ie. 1/2 = x/y

But what is a frame of reference anyways?  In a block universe, how is it physically relevant?

9 hours ago, swansont said:

Just as there are different kinetic energies; it depends on who does the measuring. Length, like kinetic energy, is a relative quantity.

Two measurements by two different observers does not mean anything is in two positions at once, just as it doesn’t have two speeds at once. A superposition is measured by a single observer.

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.

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28 minutes ago, studiot said:

Do you not think this statement gives the wrong impression ?

Here is a story

There is a long straight road through the middle of my village where the speed limit is the standard 30mph.
However so many drivrs fail to observe the speed limit that the local neighbourhood watch has set up a speedwatch.
They have two identical portable radar guns and their procedure is to calibrate or synchronise the guns by observing Jeff driving through the village, whilst standing together at the roadside.
Having agreed that both guns give the same reading, Jim gets in the car with Jeff who follows behind a driver driving through the village.
Jack stays by the roadside and reads the speed of the driver on his gun as a steady 40mph.
In Jeff's car, Jim reads a different steady speed of 10mph on his gun.

So does the errant driver have two speeds ?

I'm just trying to deal with the question this poster is posing, which seems to betray a misunderstanding, very likely the notion of a preferred frame of reference. But feel free to correct the misapprehension in a different way if you think it would be clearer.

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28 minutes ago, 34student said:

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.

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7 hours ago, exchemist said:

Yes, there are two lengths, if you like. The point about relativity, which you seem not to have absorbed, is that measurements of length (and time) are not absolute. There is no single "true" value for them. Any measurement of them depends on the viewpoint (frame of reference) from which they are measured and all are equally "true". If you still can't grasp this I suggest going back to your books and reading carefully what relativity says.

Nothing can inhabit two different reference frames at once. So you can't do QM (for example) from the viewpoint of two different reference frames at once either.  Which means that relativity does not lead to a superposition of states, as you originally suggested.

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.

57 minutes ago, swansont said:

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.

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9 minutes ago, 34student said:

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.

You are free to open a thread in speculations and present evidence to support this claim. Assertions are insufficient, and this is also not in keeping with relativity, so it has no place in this discussion.

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2 hours ago, exchemist said:

I'm just trying to deal with the question this poster is posing, which seems to betray a misunderstanding, very likely the notion of a preferred frame of reference. But feel free to correct the misapprehension in a different way if you think it would be clearer.

Yes I understand that and I'm sure you understand that there is only one length, it is just that different observers will assess it differently.

That is the point of my little story and the point swansont has been trying to drive home.

I can't see how apparently accepting the OP false statement that there are two lengths as opposed to two assessments of one length helps.

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1 hour ago, 34student said:

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.

This "block universe" stuff has nothing to do with anything we have been discussing. Suggest sticking to the subject.

11 minutes ago, studiot said:

Yes I understand that and I'm sure you understand that there is only one length, it is just that different observers will assess it differently.

That is the point of my little story and the point swansont has been trying to drive home.

I can't see how apparently accepting the OP false statement that there are two lengths as opposed to two assessments of one length helps.

There are two measurements, that's all I meant. But I'm not really interested in getting into a debate with you about your little story. I'm getting bored with this now. If you can explain the issue more clearly to our poster, go ahead.

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2 hours ago, exchemist said:

This "block universe" stuff has nothing to do with anything we have been discussing. Suggest sticking to the subject.

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.

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15 hours ago, 34student said:

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.

I'm out of this discussion now. You have basic errors in understanding, that you need to sort out before you go any further, as many people more adept than I have tried to explain to you.

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18 hours ago, 34student said:

Just replace "block universe" with "general relativity" in my last post to you.

Ok:

22 hours ago, 34student said:

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.

The above text then becomes: "There is no physical speed or movement of any sort in General Relativity.  Frame of reference has no physical meaning; it can not change anything."  That can't possibly be correct?

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8 hours ago, Ghideon said:

Ok:

The above text then becomes: "There is no physical speed or movement of any sort in General Relativity.  Frame of reference has no physical meaning; it can not change anything."  That can't possibly be correct?

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

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34 minutes ago, 34student said:

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

It is true that there are quantities in GR that do not depend on choice of reference frame, ie everyone agrees on them. These are tensors and their invariants.

However, there are also coordinate quantities, which are those that are based on measurements of space, time or energy in isolation. These depend on the observer, as they are by nature relational quantities.

So, whether or not the choice of frame is important will depend on which quantities you want to discuss. Saying that reference frames ‘don’t change anything’ is a bit too simplistic.

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2 hours ago, Markus Hanke said:

It is true that there are quantities in GR that do not depend on choice of reference frame, ie everyone agrees on them. These are tensors and their invariants.

However, there are also coordinate quantities, which are those that are based on measurements of space, time or energy in isolation. These depend on the observer, as they are by nature relational quantities.

So, whether or not the choice of frame is important will depend on which quantities you want to discuss. Saying that reference frames ‘don’t change anything’ is a bit too simplistic.

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?

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3 hours ago, 34student said:

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?

Frame of reference is looking at something from one particular perspective vs looking at the same thing from a different perspective. Even though there's only the one abstract Distance there are an infinite number of perspectives.

Need to mentally seperate the two concepts.

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9 hours ago, 34student said:

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.

I think you are incorrect about what “we” know

9 hours ago, 34student said:

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.

Why does “existing in a physical sense” matter?

9 hours ago, 34student said:

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.

The shape is not inherent. The best you can do is say what the shape is in a particular frame, such as the rest frame.

9 hours ago, 34student said:

Going back to my OP, how can we avoid some sort of superposition of position?

It’s trivial to avoid. There is no superposition, as has been explained multiple times.

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• swansont changed the title to Does length contraction imply a superposition of particles? [answered: no]
6 hours ago, Endy0816 said:

Frame of reference is looking at something from one particular perspective vs looking at the same thing from a different perspective. Even though there's only the one abstract Distance there are an infinite number of perspectives.

Need to mentally seperate the two concepts.

What do you mean when you say that there is only the one abstract distance?

5 hours ago, swansont said:

I think you are incorrect about what “we” know

I hope someone on here corrects you.  I did not say anything wrong there.

5 hours ago, swansont said:

Why does “existing in a physical sense” matter?

If something is not physical, it is inert, not relevant, unobservable, not scientific, etc.

5 hours ago, swansont said:

The shape is not inherent. The best you can do is say what the shape is in a particular frame, such as the rest frame.

Do both shapes exist?

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51 minutes ago, 34student said:

What do you mean when you say that there is only the one abstract distance?

I imagine it means there is a distance from A to B.

But that distance is relative to the frame from which it is measured.

51 minutes ago, 34student said:

I hope someone on here corrects you.  I did not say anything wrong there.

I don’t think anyone who understands physics is going to. I suppose a crackpot could show up and do so.

51 minutes ago, 34student said:

If something is not physical, it is inert, not relevant, unobservable, not scientific, etc.

Length is not a physical object. Neither is time. They are relevant and scientific.

51 minutes ago, 34student said:

Do both shapes exist?

Yes. The issue was being inherent. A square that is measured by a moving observer will not have four sides of equal length. The shape in the rest frame is not inherent.

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11 hours ago, 34student said:

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.

Again, you are ignoring frames of reference.
For an 'external' observer, the relativistically moving Muon has its time dilated, allowing it to reach the surface of the Earth.
For an observer travelling along with the Muon, the distance to the surface of the Earth is contracted, allowing the Muon to reach the surface.
The two FoR give differing observations of distances and durations, as measured from those particular frames.
That is what people have been telling you in all of your threads.

You do not understand the 'block' universe model, where an observer in a particular FoR sees a foliation, or slice, of the 4d hypercube, yet you keep bringing it up.
Nor do you understand Relativity as you don't seem to grasp the importance of FoRs.
Maybe you should start from the beginning and ask what happens in specific circumstances, instead of telling us what you think happens.

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The muon experiment is one of the few I really have understood, as an example of relativistic contraction.  When I have too much to drink, I take on the perspective of a muon, because I seem to reach the ground more quickly than expected.

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1 hour ago, swansont said:

I don’t think anyone who understands physics is going to. I suppose a crackpot could show up and do so.

What I said is very well known and understood.  I am surprised that you do not know that.

1 hour ago, swansont said:

Length is not a physical object. Neither is time. They are relevant and scientific.

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.

1 hour ago, swansont said:

Yes. The issue was being inherent. A square that is measured by a moving observer will not have four sides of equal length. The shape in the rest frame is not inherent.

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.

1 hour ago, MigL said:

Again, you are ignoring frames of reference.
For an 'external' observer, the relativistically moving Muon has its time dilated, allowing it to reach the surface of the Earth.
For an observer travelling along with the Muon, the distance to the surface of the Earth is contracted, allowing the Muon to reach the surface.
The two FoR give differing observations of distances and durations, as measured from those particular frames.
That is what people have been telling you in all of your threads.

I know this.  That is why I brought up the muon example.  I do not know what you are contesting.

1 hour ago, MigL said:

You do not understand the 'block' universe model, where an observer in a particular FoR sees a foliation, or slice, of the 4d hypercube, yet you keep bringing it up.
Nor do you understand Relativity as you don't seem to grasp the importance of FoRs.
Maybe you should start from the beginning and ask what happens in specific circumstances, instead of telling us what you think happens.

I have said nothing wrong.  Please tell me what I said that is wrong.

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49 minutes ago, 34student said:

I have said nothing wrong.  Please tell me what I said that is wrong.

And people have been telling you for two pages already, but you simply ignore them and go on.
That's no way to learn anything ...

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