Endy0816 Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 12:58 AM, 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. Expand 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
swansont Posted December 12, 2021 Posted December 12, 2021 On 12/11/2021 at 11:31 PM, 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? Expand Just as there are different kinetic energies; it depends on who does the measuring. Length, like kinetic energy, is a relative quantity. On 12/12/2021 at 12:58 AM, 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 Expand 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.
exchemist Posted December 12, 2021 Posted December 12, 2021 On 12/11/2021 at 11:31 PM, 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? Expand 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. 1
studiot Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 10:13 AM, exchemist said: Yes, there are two lengths, if you like. Expand 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 ?
34student Posted December 12, 2021 Author Posted December 12, 2021 On 12/12/2021 at 4:09 AM, 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 Expand But what is a frame of reference anyways? In a block universe, how is it physically relevant? On 12/12/2021 at 8:21 AM, 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. Expand 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.
exchemist Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 5:47 PM, 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 ? Expand 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.
swansont Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 5:53 PM, 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. Expand Don’t change the subject. You asked about superposition and relativity, not about the block universe interpretation. If you want to ask about the block universe, open a new thread.
34student Posted December 12, 2021 Author Posted December 12, 2021 On 12/12/2021 at 10:13 AM, 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. Expand 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. On 12/12/2021 at 6:21 PM, swansont said: Don’t change the subject. You asked about superposition and relativity, not about the block universe interpretation. If you want to ask about the block universe, open a new thread. Expand 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.
swansont Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 7:16 PM, 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. Expand 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.
studiot Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 6:19 PM, 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. Expand 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.
exchemist Posted December 12, 2021 Posted December 12, 2021 On 12/12/2021 at 7:16 PM, 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. Expand This "block universe" stuff has nothing to do with anything we have been discussing. Suggest sticking to the subject. On 12/12/2021 at 8:35 PM, 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. Expand 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.
34student Posted December 12, 2021 Author Posted December 12, 2021 On 12/12/2021 at 8:43 PM, exchemist said: This "block universe" stuff has nothing to do with anything we have been discussing. Suggest sticking to the subject. Expand 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.
exchemist Posted December 13, 2021 Posted December 13, 2021 On 12/12/2021 at 10:59 PM, 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. Expand 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.
Ghideon Posted December 13, 2021 Posted December 13, 2021 On 12/12/2021 at 10:59 PM, 34student said: Just replace "block universe" with "general relativity" in my last post to you. Expand Ok: On 12/12/2021 at 7:16 PM, 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. Expand 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?
34student Posted December 14, 2021 Author Posted December 14, 2021 On 12/13/2021 at 5:20 PM, 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? Expand From what I understand about general relativity, it is correct.
Markus Hanke Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 1:33 AM, 34student said: From what I understand about general relativity, it is correct. Expand 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.
34student Posted December 14, 2021 Author Posted December 14, 2021 On 12/14/2021 at 2:14 AM, 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. Expand 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?
Endy0816 Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 5:58 AM, 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? Expand 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.
swansont Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 5:58 AM, 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. Expand I think you are incorrect about what “we” know On 12/14/2021 at 5:58 AM, 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. Expand Why does “existing in a physical sense” matter? On 12/14/2021 at 5:58 AM, 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. Expand 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. On 12/14/2021 at 5:58 AM, 34student said: Going back to my OP, how can we avoid some sort of superposition of position? Expand It’s trivial to avoid. There is no superposition, as has been explained multiple times.
34student Posted December 14, 2021 Author Posted December 14, 2021 On 12/14/2021 at 9:23 AM, 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. Expand What do you mean when you say that there is only the one abstract distance? On 12/14/2021 at 10:40 AM, swansont said: I think you are incorrect about what “we” know Expand I hope someone on here corrects you. I did not say anything wrong there. On 12/14/2021 at 10:40 AM, swansont said: Why does “existing in a physical sense” matter? Expand If something is not physical, it is inert, not relevant, unobservable, not scientific, etc. On 12/14/2021 at 10:40 AM, 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. Expand Do both shapes exist?
swansont Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 4:05 PM, 34student said: What do you mean when you say that there is only the one abstract distance? Expand 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. On 12/14/2021 at 4:05 PM, 34student said: I hope someone on here corrects you. I did not say anything wrong there. Expand I don’t think anyone who understands physics is going to. I suppose a crackpot could show up and do so. On 12/14/2021 at 4:05 PM, 34student said: If something is not physical, it is inert, not relevant, unobservable, not scientific, etc. Expand Length is not a physical object. Neither is time. They are relevant and scientific. On 12/14/2021 at 4:05 PM, 34student said: Do both shapes exist? Expand 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.
MigL Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 5:58 AM, 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. Expand 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.
TheVat Posted December 14, 2021 Posted December 14, 2021 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.
34student Posted December 14, 2021 Author Posted December 14, 2021 On 12/14/2021 at 5:05 PM, swansont said: I don’t think anyone who understands physics is going to. I suppose a crackpot could show up and do so. Expand What I said is very well known and understood. I am surprised that you do not know that. On 12/14/2021 at 5:05 PM, swansont said: Length is not a physical object. Neither is time. They are relevant and scientific. Expand 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. On 12/14/2021 at 5:05 PM, 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. Expand 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. On 12/14/2021 at 5:37 PM, 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. Expand I know this. That is why I brought up the muon example. I do not know what you are contesting. On 12/14/2021 at 5:37 PM, 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. Expand I have said nothing wrong. Please tell me what I said that is wrong.
MigL Posted December 14, 2021 Posted December 14, 2021 On 12/14/2021 at 6:19 PM, 34student said: I have said nothing wrong. Please tell me what I said that is wrong. Expand Just about everything you've said. 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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