- #351
ghwellsjr
Science Advisor
Gold Member
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I hear you saying you understand that it is not necessary to assign multiple coordinate systems to each observer/object, but we'll see what you really believe when I address one of your answers down below.GrayGhost said:...
Now now. You should consider that you may be reading something into my statements that are not there.
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If it does indicate to you as such, then you're mis interpreting what I said. There is no requirement to assign coordinate systems to anything including oneself, however one may also always imagine it is done so even if it was not. There's no harm in it.
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Of course. I just can't figure out why you feel the need to tell me? I could tell you the same thing, but what good does it do?
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Yes, he did assign a coordinate system to the accelerating clock, it was the stationary system as he called it.GrayGhost said:Indeed, he did not assign any coordinate system to the accelerating clock. This doesn't mean that one cannot imagine an observer carrying the clock, who assigns himself the origin of a coordinate system he calls his own. Bottom line, it was an extrapolation of the LTs by Einstein to the accelerational case. Here's what he did ...
No, he didn't say it was from the POV of an inertial clock. He said both clocks are "viewed in the stationary system". He didn't say or imply and it's not true that what he described about what the traveling clock experiences is what the stationary clock sees. We, as super observers, can "see" both clocks simultaneously according to our arbitrarily assigned coordinate system, but there is no implication that we have determined what either of them sees of the other one (until they are colocated again).GrayGhost said:As you pointed out, said OEMB scenario presented an accelerating clock from the POV of an inertial clock. Of course, because the LTs are based upon the POV of a stationary observer.
Einstein didn't use any LT in his analysis of the traveling clock because he only used one frame of reference. LT are for the purpose of seeing what coordinates are assigned to the same even in two frames of reference.GrayGhost said:However, the LTs were also designed for moving inertial bodies of constant v. Einstein tactically specified that his accelerating clock move at a constant velocity v, while it moved in curvilinear motion. As you know, gamma does not depend upon the direction of motion, but rather only the relative speed. Therefore, since his accelerating clock is always the same specific v in any instant, the value of gamma must remain constant as well, since it depends on v (ie speed) and not x or t. So per the stationary POV, the accelerating clock must tick slower by the same rate an always inertial clock of the same velocity would.
Equally tactical, Einstein begins and ends the interval with the 2 clocks colocated, and so no observer in the cosmos may disagree on the outcome. The accelerating clock must tick slower per the stationary clock, and thus must age less over the common interval. However, although the accelerating clock must agree that it ages less, Einstein makes no conjecture as to the relative rate of that always-inertial clock per the accelerating clock. However, just the fact that the accelerating clock must age less over the defined interval, was an extrapolation of the special case to the more general case. My opinion is that the LTs also apply from the non-inertial POV, although the process of their application is not so easy.
As long as you have assigned coordinates to all significant events according to one inertial frame of reference, you cannot learn anything by using the LT to see what those coordinates look like in another frame of reference. LTs will not help you in your Darth Vader scenario unless you have previously answered the question in one FOR.GrayGhost said:Well, amonst other things, it does explain why the muon decays (as it does) as it transcends the atmosphere to earth. If folks could fly at luminal speeds from here to there, it would be nice to know in advance how much you'll age relative to others over the interval. Another way of looking at it, let's say you have intel that Darth Vader will emit a particle beam that destroys Earth at 11:24pm by his own clock. You can predict the last moment you can destroy him before he destroys the earth, assuming he flies inertially over the interval and you knew his clock readout at some prior point :)
The point would be for the same reasons I mentioned above for the all-inertial case.
What you would learn is how mother nature really works. The LTs show how the dimensions are related by velocity under an invariant c. That's a great advancement in physics, and cosmology as well. The LTs explain the nature of spacetime in the special case. If our understanding of the nature of spacetime can be extended to the more general case (devoid of gravity), I see it as no less important than the advancement under the special case.
Add, folks are generally very interested in answering the questions that remain unanswered. Often, there are many different opinions as to how to answer a yet unanswered question. That usually suggests that all those competing theories are wrong. Usually, when the correct theory arises, everyone knows it and agrees, although it may take some time to be accepted. Beyond SR, if there is a correct transformation between any 2 frames in flat spacetime, then I for one want to know what it is.
I'll give you an A for persistence :) I hope you feel like you helped me get whatever it is that you believed I need.
GrayGhost
This, by the way, is the source of many so-called SR confusions and paradoxes; assigning half the coordinates for one observer/object according to one FOR and assigning the other half for another observer/object according to another FOR and trying to answer questions about how to reconcile them. It can't be done. If you do it completely in one FOR for all observers/objects (like you're supposed to), then you'll have all your answers, but if you want, you can also see how those coordinates look for the same events according to any other FOR. By the way, I'm always talking about inertial FORs, if you want to talk about non-inertial, you're on your own.
Let me repeat, nobody in our scenarios owns any FOR. All observers/objects are equal in terms of the information they have independent of any FOR. We, as super observers can talk about what all the observers and objects in our scenario experience if we do extra work in analyzing that POV for each of them. Their individual POVs are not helped by our assigning a FOR in which they are stationary and they can't do it themselves without us, as super observers telling them things that we know that they cannot know.
I'll be persistent with you as long as you continue to not get it, but I'd rather you see the light and say "oh, now I get it".
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