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RAGORDON2010

Another way of looking at Special Relativity

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51 minutes ago, Mordred said:

To provide better clarity. You need the new viriable to distinguish coordinate time from proper time.

 A helpful hint past the oft over complicated distinction between the two. 

 Coordinate time is the time at a specific coordinate event. While proper time is any location along the worldline between any two events. (Emitter,observer). Where  [math]\tau[\math] is the proper time. The further qualification is that proper time is the invariant time where all observers can agree upon. This is set by the Einstein synchronization rules.

Hi Mordred,

My comment was specifically about Minkowski's original 4D World, where he used tau to distinguish as I posted way back on the previous page.
until the introduction of 'proper time' this was the use of tau.

Quote

studiot

mink4.jpg.76b6032c611244199c103e097ee206a4.jpg


Which I grant you is confusing, especially as in the original paper Einstein used tau as time in the second frame.

Quote

Einstein

To any system of values x, y, z, t which completely defines a place and time of an event in the stationary system, there belongs a system of values ξ. η, ζ, τ determining that event relative to the system k, and our task is now to find the system of equations connecting these quantities.

 

Minkowski has always been acknowledged as an alternative simpler route to obtain the same end result.

Edited by studiot

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Yes the original SR defined proper time as the at rest frame. GR treats all reference frames as inertial. Good point to keep in mind. +1

Edited by Mordred

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7 hours ago, RAGORDON2010 said:

-The Fact of Nature that the speed of light is the same in all inertial frames plays NO role in explaining the successful application of Special Relatively to solving physical problems!  It is a Red Herring! There is another Fact of Nature at work here.

It’s the basis for time dilation and length contraction. It does need to be separately applied to solve the problems, true, but that’s true of lots of models. 

 

7 hours ago, RAGORDON2010 said:

 

I would say that accelerating a particle becomes more difficult as particle speed approaches c because the external field responsible for the acceleration loses effectiveness as the particle speed approaches the speed at which the field mechanisms function.

This, of course, offers an explanation for why light speed forms a limiting speed in nature.  An old boot can travel no faster through the water than the maximum speed at which the fisherman can reel in the line.

Whenever I think about this phenomenon, Paul Simon's song comes to mind. The speeding particle slips and slides away from the grasp of the external field.

What if no field is involved?

7 hours ago, RAGORDON2010 said:

 

Thought 3 -

I can’t leave this forum without saying something about time dilation.  It has always puzzled me that while the physics community easily accepts that time dilation effects in General Relativity relate in some way to the interaction between the time-keeping system and the surrounding gravitational field, the analogous time dilation effects in Special Relativity are viewed as “just so”.  Well, I have never cared much for a “just so” story.  But I do hold the view that Nature does not care at all for a “just so” story.  Something is going on out there!

In the most dominant example - the retarded decays of unstable particles moving at speeds close to light speed - I again must fall back on my belief that these effects are in some way a consequence, in ways not at all understood, of the rapid motion of the particles through surrounding electric and magnetic fields.

But it’s not a function of field strength. It’s there for weak fields, and for particles that aren’t unstable.

And they aren’t “just so” as they can be derived from the basic principles.

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2 hours ago, Mordred said:

Yes the original SR defined proper time as the at rest frame. GR treats all reference frames as inertial. Good point to keep in mind. +1

Where is that defined? Do you mean that it used tau for something other than proper time? Tau (like other letters) is used to mean different things in different contexts.

Proper time is defined along the world line of a clock traveling along a spacetime interval, ie. only timelike intervals. It shouldn't be used to describe time away from the clock or throughout the frame, because that's not what it is. The proper time of an inertial clock measures the same time as any other clock elsewhere in the inertial frame, but that doesn't mean they're called the same thing. The proper time measured by an accelerating clock doesn't describe time elsewhere, because you can't synchronize with another clock, due to relativity of simultaneity. Even if you have two coordinated accelerating clocks that measure the same in a given inertial frame, they're not "Einstein synchronized" and won't agree with each other in the clocks' respective reference frames because in one clock's accelerated reference frame, the other clock accelerates at different times and has a non-zero relative velocity. Therefore the proper time measured by one accelerated clock can't remain the same all along its world line, as the proper time measured by any otherwise located clock, right?

 

Edit: I think I'm confused as to what I'm replying to, I got the sense from this thread that "proper time" was incorrectly being used to describe time in a reference frame in which a given clock is at rest, but I can't find what gave me that impression.

Edited by md65536

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On 11/6/2019 at 12:40 AM, studiot said:

If you only have one frame of reference than you have the difficulty that Fitzgerald (and Lorenz) faced with the results of practical measurements on the propagation of light.

This was that the Lorenz-Fitzgerald contraction was introduced as a mathematical formula which accounted for but did not explain the results of these experiments (in particular the Michelson and Michelson -Morley ones)

Length contraction of the apparatus arms was a pretty heretical explanation.

No, you can live in a quite comfortable way with a single frame, and apply, instead, Lorentz transformations to particular solutions.  This gives you different, Doppler-shifted solutions. 

There was a simple explanation proposed by Lorentz.  Namely, if what holds together condensed matter is the EM force, then condensed matter has to have the same symmetry properties as the EM equations.  Thus, a Lorentz-transformed (Doppler-shifted) solution for some piece of condensed matter will be a solution too.  But the Lorentz-transformed piece of matter is contracted.  

The actual explanation works in the same way, we have a lot more fields in the SM, but they all are wave equations with the same c, so that a Lorentz-transformed solution will be a solution too.  

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38 minutes ago, md65536 said:

Where is that defined? Do you mean that it used tau for something other than proper time? Tau (like other letters) is used to mean different things in different contexts.

Proper time is defined along the world line of a clock traveling along a spacetime interval, ie. only timelike intervals. It shouldn't be used to describe time away from the clock or throughout the frame, because that's not what it is. The proper time of an inertial clock measures the same time as any other clock elsewhere in the inertial frame, but that doesn't mean they're called the same thing. The proper time measured by an accelerating clock doesn't describe time elsewhere, because you can't synchronize with another clock, due to relativity of simultaneity. Even if you have two coordinated accelerating clocks that measure the same in a given inertial frame, they're not "Einstein synchronized" and won't agree with each other in the clocks' respective reference frames because in one clock's accelerated reference frame, the other clock accelerates at different times and has a non-zero relative velocity. Therefore the proper time measured by one accelerated clock can't remain the same all along its world line, as the proper time measured by any otherwise located clock, right?

This quick search pulls up one related paper. When I first was introduced to Relativity WAY back around 1980 I recall being taught the at rest definition. When precisely the change occurred (for the better ) I couldn't tell you. As it largely arose from misconceptions.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.humanities.mcmaster.ca/~rarthur/papers/Mptatch.pdf&ved=2ahUKEwinmOX5jeHlAhWQsJ4KHV8PB9IQFjARegQICxAB&usg=AOvVaw2NawrchGmi31GDfvPw4ZoL

 

Edited by Mordred

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31 minutes ago, Mordred said:

This quick search pulls up one related paper. When I first was introduced to Relativity WAY back around 1980 I recall being taught the at rest definition. When precisely the change occurred (for the better ) I couldn't tell you.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.humanities.mcmaster.ca/~rarthur/papers/Mptatch.pdf&ved=2ahUKEwinmOX5jeHlAhWQsJ4KHV8PB9IQFjARegQICxAB&usg=AOvVaw2NawrchGmi31GDfvPw4ZoL

 

Ah thanks, I was worried for a minute there.

If I understand that pdf correctly, there was only ever one definition of "proper time", introduced by Minkowski. Other conflicting (but common) uses are described as stemming from confusion. It sounds like you were first taught the incorrect use.

From the paper:

Quote

The conflation of proper time with co-­‐ordinate time in a system’s own rest frame is also perhaps fostered by the numerical equivalence of the value of the proper time elapsed for a body moving along an inertial path with the value measured by the time-­‐co-­‐ordinate in its rest frame. Thus it is often said that proper time is simply time measured in a body’s “proper frame”, as if a body keeps its own inertial frame while accelerating! There are two confusions here: first, the idea that a body “has” an inertial frame, when a reference frame is just a point of view for representing the body’s motion, and (according to the principle of relativity) one can represent this motion equivalently from any inertial frame; and second, of course, the idea that the body could stay in the same inertial frame even though it is accelerating, and therefore moving non-­‐inertially. At any rate, this is a confused idea of proper time, which is not a time co-­‐ordinate and was not introduced by Einstein, but by Minkowski, in his famous paper of 1908 (Lorentz et al. 1923, 73-­‐91).

Just to add 2 cents, you can have a "momentary inertial frame" at any time, as an accelerating object effectively moves between different inertial frames. But you can't have a standard frame of reference with spatial extent follow the accelerating object, because different locations within the frame must accelerate at different times, and you'd need some additional (non-standard) definition of when those other locations follow the object. Does that make sense? It means that proper time is a measure of time at the location of the clock, but not elsewhere. I'm going off on a tangent to the main topic, other than that it's all related.

 

Edited by md65536

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Sounds like your describing proper acceleration see

https://en.m.wikipedia.org/wiki/Acceleration_(special_relativity)

Quote

In infinitesimal small durations there is always one inertial frame, which momentarily has the same velocity as the accelerated body, and in which the Lorentz transformation holds

you may notice that link mentions rest acceleration lol. Note the use of Infinitisimal extent. When you accelerate you undergo a type of Lorentz boost called rapidity and this changes worldlines as a worldline is as invariant.

Edited by Mordred

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23 minutes ago, Mordred said:

Sounds like your describing proper acceleration see

https://en.m.wikipedia.org/wiki/Acceleration_(special_relativity)

you may notice that link mentions rest acceleration lol. Note the use of Infinitisimal extent.

No, there is still confusion here.

From wikipedia: "In relativity, proper time along a timelike world line is defined as the time as measured by a clock following that line."

The fact that it is invariant can be paraphrased as: Every observer (every frame of reference) agrees that the clock measured some specific (agreed upon) time at any given event along the path. Eg. everyone agrees that your watch said 12:00 when you were at the base of the mountain and 2:00 when you got to the top. What they won't all agree on is that a clock in town (a non-negligible distance away wrt. speed of light) said 12:00 when you were at the base and 2:00 when you were at the top. (And I add, if you had a drone that followed you at a fixed distance (Born rigid say), and the clock on the drone said 12:00 when you started and 2:00 when you got to the top, not everyone would agree that your watch and the drone were synchronized.)

I think "infinitesimal extent" applies to both for the same reasons.

34 minutes ago, Mordred said:

When you accelerate you undergo a type of Lorentz boost called rapidity and this changes worldlines as a worldline is as invariant.

No, your world line is defined by the path you take through 4d space, including however you accelerate. You never go off your world line, or have to change worldlines.

Say you accelerate by stepping off an inertial train, onto the ground. The world lines of you and the train diverge at that point, but you don't change worldlines.

Your worldline is invariant within its spacetime, and its particular coordinate system. The invariance means that everyone agrees that you pass through a particular set of events and that you do so at the time you measure yourself doing so. Not that the coordinates of those events in different reference frames are the same.

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A curve M in [spacetime] is called a worldline of a particle if its tangent is future timelike at each point. The arclength parameter is called proper time and usually denoted τ. The length of M is called the proper time of the worldline or particle. If the worldline M is a line segment, then the particle is said to be in free fall.[

 acceleration isn't freefall. 

https://en.m.wikipedia.org/wiki/World_line

 

 

Edited by Mordred

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On 11/9/2019 at 1:51 PM, geordief said:

Is it quite easy to research this "tensor reformulation of SR" (googling) or might a few pointers be in order?

I would say 'no'. I would say that in tensor formulation SR becomes wonderfully compact. But understanding tensors in themselves is another matter (I don't). If you are not 'fluent' with vectors and matrices, then the tensor way is definitely not easy. For a layman, sticking to simple algebra is the best way to understand SR. 

19 hours ago, geordief said:

Would you   reccommend "Gravitation" by Misner,Thorne  et al?

I wouldn't. I am sure it is a very good book, but it is a university level text book. 

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16 hours ago, RAGORDON2010 said:

In the most dominant example - the retarded decays of unstable particles moving at speeds close to light speed - I again must fall back on my belief that these effects are in some way a consequence, in ways not at all understood, of the rapid motion of the particles through surrounding electric and magnetic fields

Unsupported beliefs have nothing to do with science. In the same way that your "other way" of looking at SR has nothing to do with SR.

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20 hours ago, RAGORDON2010 said:

The Fact of Nature that the speed of light is the same in all inertial frames plays NO role in explaining the successful application of Special Relatively to solving physical problems!  It is a Red Herring! There is another Fact of Nature at work here.

<snap>

I would say that accelerating a particle becomes more difficult as particle speed approaches c because the external field responsible for the acceleration loses effectiveness as the particle speed approaches the speed at which the field mechanisms function.

<snip>

I hold (and this is where Special Relativity exhibits its most severe vulnerability as it is commonly described) that no physical effect can occur as a consequence of merely moving at a uniform speed in an inertial frame of reference.

So I was right. You should not teach SR because you do not understand SR, or even worse, you are thinking up wrong explanations. 

You can do two things: 

  • learn here what SR really is about
  • keep in love with your pet theory, and, as you seem already have chosen to do, leave the forum. 

 

 
Edited by Eise

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15 hours ago, Schmelzer said:
On 11/5/2019 at 6:10 PM, studiot said:

If you only have one frame of reference than you have the difficulty that Fitzgerald (and Lorenz) faced with the results of practical measurements on the propagation of light.

This was that the Lorenz-Fitzgerald contraction was introduced as a mathematical formula which accounted for but did not explain the results of these experiments (in particular the Michelson and Michelson -Morley ones)

Length contraction of the apparatus arms was a pretty heretical explanation.

No, you can live in a quite comfortable way with a single frame, and apply, instead, Lorentz transformations to particular solutions.  This gives you different, Doppler-shifted solutions. 

There was a simple explanation proposed by Lorentz.  Namely, if what holds together condensed matter is the EM force, then condensed matter has to have the same symmetry properties as the EM equations.  Thus, a Lorentz-transformed (Doppler-shifted) solution for some piece of condensed matter will be a solution too.  But the Lorentz-transformed piece of matter is contracted.  

The actual explanation works in the same way, we have a lot more fields in the SM, but they all are wave equations with the same c, so that a Lorentz-transformed solution will be a solution too. 

Why do you say no ?

Although your English is very good, perhaps you didn't catch my meaning.
Yes it is true that if you are only working in one frame you can apply the Fitzgerald contraction to bodies in motion relative to that frame.
(Note You cannot apply the Lorenz transformation, since by definition, that transforms values measured in one frame to those measured in a different frame.)

But all you are then doing is finding a formula that curve fits experimental results.
There is no way, that I am aware of, of deriving that formula from fundamental theoretical principles, in a single frame.

However I am quite open to someone who knows more showing me how.

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