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How does a 'field' become observer dependent?
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How does a 'field' become observer dependent?
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yor_on
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Re: How does a 'field' become observer dependent?
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Reply #220 on:
01/01/2014 13:52:01 »
And a Shapiro delay, as defined for a observer, 'far away' comparing this distance light 'propagates' to his detector with a locally defined speed of light then? Finding it to be 'slower'? Is 'c' a variable?
Nope
It's a locally defined speed of light in a vacuum, valid everywhere in the universe, that assuming the physics to be the same, everywhere I can go to measure and tell you about my results. And that my friends, are 'repeatable experiments.
You can define it as a result of time dilation, as described from the 'far away' observers frame of reference when calculating the result, finding that a 'curved SpaceTime' does not cover the 'slowness' he theoretically finds. You might also consider that if 'c' and and a arrow is inseparable, from a strictly local beginning, and as I think, then as I define the arrow to become 'slower' measuring over frames of reference, I also must consider 'c' to 'slow down'.
So is it a illusion?
Nope. As long as we define a universe containing ourselves it's not. It's a valid description of a universe, as measured by a 'far observer'. But please, use a definition going out from locality for it. Because that's 'c', and that's what I define as equivalent to a arrow of time. Split 'c' and you get the best clock existing. And that is the ground floor from where we can define such things as the Shapiro delay, Lorentz transformations, and a logical universe.
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Re: How does a 'field' become observer dependent?
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Reply #221 on:
01/01/2014 13:58:54 »
How would you get to a Lorentz transformation without first defining 'c'? And do you think a Shapiro delay can be Lorentz transformed?
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Re: How does a 'field' become observer dependent?
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Reply #222 on:
01/01/2014 14:02:50 »
If a Shapiro delay can't be Lorentz transformed it either has to be a wrong approach, or relativity has to be wrong. SR creates GR, using 'c' and 'gravity'.
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Re: How does a 'field' become observer dependent?
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Reply #223 on:
01/01/2014 14:45:35 »
I used to find relativity complicated, but it's not. What is complicated are the conclusions you can draw from defining different 'systems' from reading about it. So it can fool us a lot.
Relativity springs from 'c', that's the axiom telling us that it doesn't matter what 'relative motion' you measure, using infalling light or any other heavenly bodies, the speed of light in a vacuum will still be 'c' as measured in a 'two way experiment'. And that one is correct..
Using that one you need time dilations, and you need Lorentz contractions. To explain how 'c' can be 'c', no matter how fast I'm 'moving'. Nota bene, to me it won't matter if you introduce accelerations or not, for that very local definition of 'c', although to be strict about it we must use 'c' as described from 'uniform motion'.
So that's where you get time dilations and Lorentz contractions.
Then you go to GR, which treats gravity, and so matter, It does it by defining all energy as equivalent to mass, then defining gravity as inseparable from the effect you experience sitting in a uniformly constantly accelerating rocket, as measured by a accelerometer. The equivalence principle.
Notice one thing there though. It's about a 'local definition', just as 'c' is. But if gravity is 'motion' then you must find time dilations and Lorentz contraction even when being 'at rest' with Earth. And that one is proved by NIST, at centimeters.
It's our instruments that draws the line there, if we had a 'perfect' instrument 'ticking' at Planck scale ('c' is one Planck length in one Planck time) we would be able to track this relation between gravity and time dilations (Lorentz contractions) even further. But we meet HUP (Heisenberg's uncertainty principle) long before that, so it's just not possible.
You might say that it 'smears out' at a very small scale.
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Re: How does a 'field' become observer dependent?
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Reply #224 on:
01/01/2014 14:51:54 »
And you can simplify time dilations and Lorentz contractions by using this fact, that those are all 'local descriptions'. Just stop thinking of it, the 'universe', as some container. It's much easier to define it locally. Doing so you will need a complementary description of 'dimensions' though, and that, I suspect
is what 'degrees of freedom' is all about. A simplification of 'dimensions', or as I think of it, a correction and better description.
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Re: How does a 'field' become observer dependent?
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Reply #225 on:
01/01/2014 15:00:39 »
Using the idea of describing a dimensionality from locality we find that describing something, inside a lattice for example, as behaving in a 'two dimensional' manner is perfectly acceptable. It is not acceptable from the idea of a universe consisting of three singular dimensions and a arrow though. That one is rather easy to disprove, as you then need this two dimensional 'system', described in/by your lattice to 'disappear' from some angle of observation. It's not logically acceptable, as it won't happen in any experiment. Or you will have to define that as there can be no 'lower dimensional systems' existing in a 'higher dimensional system' invalidating most of the physics we use, as strings and loops etc.
=
spelling sux.
Keep missing words
==
That was actually the way I thought of it first, as if the universe we saw was made out of 'whole 4-D representations' in each point, also described locally to fit my thoughts. But using 'degrees of freedom' I think I would prefer to move away from that one, instead defining it as 'connections' expressing interactions. Those 'connections/interactions (relations) creating' what dimensions we measure. And so this lattice can be allowed to be 'two dimensional' for all practical purposes, and possibly even theoretically, as there is nothing stopping any sort of 'dimensionality' that I can see, more than whatever constraints being imposed by constants, properties, principles etc.
Einstein did not use a geometrical approach, defining relativity. And assuming this type of description, he might have been closer to the truth than the geometrical approach is, although that one is much clearer for us laymen. All as I think of it, naturally, as well as understands it, that is
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Last Edit: 02/01/2014 02:18:46 by yor_on
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Re: How does a 'field' become observer dependent?
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Reply #226 on:
01/01/2014 15:02:12 »
So, degrees of freedom
a better approach.
I'm sure you will agree on that one.
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Re: How does a 'field' become observer dependent?
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Reply #227 on:
01/01/2014 15:07:53 »
Because when you describe dimensionality from an idea of 'connections', locally defined, that means that your experiments (relations) must define your universe. And it also allows for different observers having different relations. So, dimensions falls away, and instead we will use 'degrees of freedom'.
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Re: How does a 'field' become observer dependent?
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Reply #228 on:
01/01/2014 15:10:21 »
But there is something more to such a definition, presuming a 'logical universe'. It must presume something being constant for all observers, giving them, and the universe, a coherence. What you see, and me, as we go out at night to look at the sky. 'Our' universe.
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Re: How does a 'field' become observer dependent?
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Reply #229 on:
01/01/2014 15:12:12 »
And that must be local constants, principles and properties. We share them, everywhere, and they are our background.
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Re: How does a 'field' become observer dependent?
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Reply #230 on:
02/01/2014 02:15:45 »
Now, where does a property come from?
spin?
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Re: How does a 'field' become observer dependent?
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Reply #231 on:
02/01/2014 09:49:06 »
If you're asking yourself that one, you also might want to wonder what a nucleons 'rest mass' is, and you either define it as a rest mass, ignoring any thought up intrinsic 'motions', or you invalidate the idea of rest mass, and so also the idea of ever being 'at rest' with anything. A electron for example uses 'orbitals', not 'orbits', and if you don't know what a orbital is a 'goggle' will tell you the difference. And why is a nucleons mass bigger than its parts, theoretically measured.
This one treats spin rather nicely,
Electron spin doesn't really exist.
But it also want us to go to a Bohr model?
Maybe this one should be read first.
Q: What is “spin” in particle physics? Why is it different from just ordinary rotation?
And a Bohr model, Magneton?
"The magnetic moment has a close connection with angular momentum called the gyromagnetic effect. This effect is expressed on a macroscopic scale in the Einstein-de Haas effect, or "rotation by magnetization," and its inverse, the Barnett effect, or "magnetization by rotation." In particular, when a magnetic moment is subject to a torque in a magnetic field that tends to align it with the applied magnetic field, the moment precesses (rotates about the axis of the applied field). This is a consequence of the angular momentum associated with the moment.
Viewing a magnetic dipole as a rotating charged sphere brings out the close connection between magnetic moment and angular momentum. Both the magnetic moment and the angular momentum increase with the rate of rotation of the sphere. The ratio of the two is called the gyromagnetic ratio, usually denoted by the symbol γ.
For a spinning charged solid with a uniform charge density to mass density ratio, the gyromagnetic ratio is equal to half the charge-to-mass ratio. This implies that a more massive assembly of charges spinning with the same angular momentum will have a proportionately weaker magnetic moment, compared to its lighter counterpart. Even though atomic particles cannot be accurately described as spinning charge distributions of uniform charge-to-mass ratio, this general trend can be observed in the atomic world, where the intrinsic angular momentum (spin) of each type of particle is a constant: a small half-integer times the reduced Planck constant ħ. This is the basis for defining the magnetic moment units of Bohr magneton (assuming charge-to-mass ratio of the electron) and nuclear magneton (assuming charge-to-mass ratio of the proton)."
And a brief history of how this term has been used.
Brief History of Bohr Magneton.
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Last Edit: 02/01/2014 10:19:18 by yor_on
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Re: How does a 'field' become observer dependent?
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Reply #232 on:
02/01/2014 10:39:09 »
It's always hard to set things into a proper perspective historically, but I found this one
N. Bohr, “On the Constitution of Atoms and Molecules”
But before that one you might want to read this commentary about Bohr and this same paper?
Niels Bohr and complementarity. by Plotnitsky. A (2012)
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Re: How does a 'field' become observer dependent?
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Reply #233 on:
02/01/2014 11:37:30 »
I'm arguing that you can't ignore the observation from the observed, and something similar seem to have been Einsteins take on it too.
"Einstein told Heisenberg that our concepts and theories decide what could be observed (Heisenberg 1971, p. 63). Einstein’s argument impressed Heisenberg and, in part, guided his work on the uncertainty relations. Einstein’s insight is crucial because it leads to a questioning of the uncritical use of the idea of observation, an idea that has been a subject of much discussion throughout the history and philosophy of science."
To me that practically means that as soon as you measure, you should consider your observations part of a larger system, defined by locality. It also means that you can't ignore your presumptions, for example a local clock and ruler. That does not presume them to be meaningless in any way, but it do mean that a pure 'local measurement' is not possible. And you can easily see why by considering that all measurements are done over 'frames of reference', now defining it from scales. You have the possibility of being 'at rest' macroscopically but that one is to me discuss-able microscopically, although correct from a macroscopic view.
==
I am of two minds, when it comes to being 'at rest' with something. The way I would try to join it is from decoherence. While you only find probabilities at a small scale, at a macroscopic scale you will find a classic predictability, and so I think of being 'at rest' with something for now. It has to be something similar to decoherence, at least to make sense to me.
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Last Edit: 02/01/2014 12:28:13 by yor_on
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Re: How does a 'field' become observer dependent?
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Reply #234 on:
02/01/2014 11:54:53 »
It also means that defining the reason why one find a rest mass of a nucleon to be larger than its 'parts', being 'energy or quarks and gluons' in 'relativistic motion' have no real meaning to me. There is no such thing as a relativistic motion there, just as atomic particles spin is no real spin.
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Re: How does a 'field' become observer dependent?
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Reply #235 on:
02/01/2014 11:57:10 »
I prefer indeterminacy to 'virtual photons'.
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Re: How does a 'field' become observer dependent?
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Reply #236 on:
02/01/2014 12:33:44 »
What one can question using locality, is whether the classically definable spin (angular momentum) of a spinning top is more 'real' than the atomic spin? After all, the classical definition of a spin comes scale wise from probability. What I probably
mean is that both has to be accepted on their 'face value'. They exist measurably, therefore they are here.
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Re: How does a 'field' become observer dependent?
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Reply #237 on:
02/01/2014 12:36:26 »
It all comes back to measurements, doesn't it? And what meaning we put into their results.
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Re: How does a 'field' become observer dependent?
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Reply #238 on:
02/01/2014 12:51:33 »
There are two ways to look at 'weak measurements', as I think of it then. You might be able to argue that by doing a lot of weak measurements of, for example, a 'photon path' you also gives 'it' a higher probability, by finding this 'path' to be the one most chosen. Or you can argue the opposite, that there are no paths, only positions in space and time, defined by locality. To do the later you need local constants, properties and principles.
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Re: How does a 'field' become observer dependent?
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Reply #239 on:
02/01/2014 12:54:41 »
Without a 'locality' existing the later interpretation becomes a hard one to argue. Only if assuming this 'background', valid everywhere, can I argue that this is one reason why weak experiments seems as working hypothesis's.
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