 ## Twin Paradox   ## Open Letter On Special Relativity

Toward An Authoritative, STANDARD Interpretation of Special Relativity

The Need: Students, you need to be sure you understand every nuance regarding the questions below! The fact that Special Relativity has meant different things to different people and that even most relativist professors have made statements that imply contradictory interpretations is well known and well documented (see the Open Letter on the Twin Paradox (http://TwinParadox.net) Section 1 of the Report page, Prof. Ian McCausland’s recent book “A Scientific Adventure: Reflections on the Riddle of Relativity” and/or , Prof. Herbert Dingle’s classic Science at the Crossroads http://www.naturalphilosophy.org/php/index.php?tab0=Books&tab1=Display&id=269&tab=3

Goal: A standard interpretation of Special Relativity requires that some authoritative physics organization or acknowledged expert provide the answers to the following very basic questions/topics. Once a standard has been defined, professors can debate and publically challenge the standard. When one writes a paper or textbook, one will need to note that the work uses the standard definition for Special Relativity or explicitly and clearly state how the author’s interpretation differs from the standard.

Value: With a clearly defined standard interpretation, for the first time in over a century, when Special Relativity is written about or discussed, all parties will know exactly what’s being discussed. Also, erroneous interpretations that lead to erroneous conclusions can be more easily avoided. In addition, if empirical findings do not match the standard interpretation but rather support a rejected interpretation, then that will add clarity to how those empirical findings should be interpreted.

Given the above, it’s clear that the physics community and the search for progress in physics would benefit significantly if and when a standard interpretation of Special Relativity was documented. It’s puzzling that this effort has not already been undertaken by the mainstream physics community itself.

See proposed Special Relativity (SR) questions below:

For any question that seems to be asking for a “Yes” or “No” answer, either a “Yes” or “No” needs to be given or a clear explanation of why one cannot answer Yes or No needs to be given – in addition, the responder should feel free to add comments that would add clarity and address any ambiguity regarding such questions.

The answer should be given in the responder’s own words briefly and clearly such that the answers to all the questions for a specific topic will be crystal clear. We are NOT asking that one choose from among the multiple questions given for a specific topic, but rather we ask that the answers given address all the questions.

In the questions below, we use a dichotomy between “physical” and “just observed”. “Just observed” is defined to be mutually exclusive with physical as in when twins separate and each twin “just observes” the other twin to shrink as the distance of separation increases whereas there is no attendant physical shrinking.

It is suggested that initially only questions # 1 and #2 be answered and reviewed for clarity to make sure we’re on the right track. After those two questions have been addressed, the remaining questions can be answered over time for a complete definition/interpretation.

The abbreviation SR is used for “Special Relativity” below.

1) Time Dilation: What is the physics meaning of SR's time dilation equation? Does it describe physical, asymmetric effects? If yes, does it mean that clocks traveling with a relative velocity will accumulate proper time at different rates as a function of that relative velocity?  If yes, does that mean that time itself is affected by relative velocity and/or is clock rate affected by relative velocity?

OR

Does it say that two observers in different inertial frames will JUST observe the other's clock to be running slow with no attendant physical effects? If yes, does SR say that observers in the S frame will directly observe clocks in the S’ frame to accumulate proper time at a slower rate than the S frame clocks? Or does, it just mean that if one measures the relative velocity of S’ with respect to S, observers in S, using the SR time dilation equation, will calculate that clocks in the S’ frame accumulate proper time at a slower rate than the S frame clocks?

2) Speed of Light: In SR, is the assertion that the one-way speed of light (in vacuum) is a constant, c, “just” a convention? If yes, does selecting that convention for the one way speed of light just mean choosing a way to view the world rather than directly describing the physical world?

OR

In SR, is the one-way speed of light physically c in all directions in all inertial frames? If yes, in SR, is that assertion based on empirical evidence? If so, what evidence?

OR

In SR, is the one-way speed of light (in vacuum) "just observed" to be c in all directions in all inertial frames whereas the actual speed may vary by direction and/or by inertial frame? If so, is the speed of light observed to be c because, in SR, clocks are synchronized using the assumption that "the speed of light is c in all directions in all inertial frames"?

3) Simultaneity: SR’s relative simultaneity seems to rule out absolute simultaneity. However, within a frame, using SR’s clock synchronization, is there any physical or practical meaning for simultaneity? If so, what is that meaning?

And

If all clocks in a frame are synchronized on noon 1/1/12, then on 1/1/13 when one clock reads noon, will all clocks have accumulated one year of proper time or not? If not, why not and what can be said about how much proper time have they accumulated?

And

In SR, do all clocks at rest in a specific inertial frame accumulate proper time at the same rate (other things being equal such as gravitational potential)?

And

In SR, do clocks at rest in a specific inertial frame, A, accumulate proper time at the same rate as clocks at rest in a different frame, B, (other things being equal such as gravitational potential)? If not, is there a specific ratio of clock rates for A & B and if not, why not?

And

In a Twin Paradox scenario, if the traveling clock loses 500 units of proper time versus the stay-at-home clock in A (at the start and stop event), will the traveling clock have also lost 500 units of proper time versus all the other clocks at rest in frame A that are ticking in unison with the stay-at-home clock? If not, why not?

4) Special Frame:
In SR, is the existence of a special frame (e.g., an ether frame) not allowed/ruled out?

OR

In SR, does a special frame exist, however, it's JUST impossible to determine which frame is the special frame?

OR

In SR, does a special frame exist and it may be possible to determine the special frame in the future?

5) Spacetime: In SR, are time and space separate or part of a single whole? If part of a single whole, does space morph into time and vice versa if, for example, one accelerates to a different constant velocity? In SR, for different inertial frames, is space different? Is time different? If so, in what way?

6) Acceleration: Can special relativistic effects such as time dilation be applied, using instantaneous relative velocity, if either or both the observer and the observed are not in inertial frames and/or are accelerating? If so, should SR be reinterpreted as not being restricted describing relative velocity between inertial frames but instead as describing the effects of instantaneous velocity? If not, why not?

7) Kinetic Energy: In SR, does kinetic energy physically increase as a function of relative velocity?  If yes, what is the physical meaning of kinetic energy, if it is not single valued for an object, but is observer dependent?

OR

In SR, does one just observe an increase in kinetic energy as a function of its relative velocity? If Yes, is SR’s construct of (relative) kinetic energy a useful abstraction to be used because the single valued, physical kinetic energy cannot be determined?

8) Spacetime Model: In SR, is there a single, consistent, physical model of spacetime? If Yes, what is it? If Yes, are space and time physically different for each observer?

OR

In SR, does each observer have their own “just observed” spacetime model?

9) Length Contraction: What is the physics meaning of SR's length contraction equation? Does it describe physical, asymmetric effects? If yes, does it mean that objects traveling with a relative velocity will contract in the direction of motion?  If yes, does that mean that space itself is affected by relative velocity and/or the length of the object is affected?

OR

Does it say that two observers in different inertial frames will JUST observe the other's meter stick, etc. contracting with no attendant physical effects?

10) Mass Increase: In SR, does mass physically increase as a function of relative velocity?  If yes, what is the physical meaning of mass, if it is not single valued for an object, but is observer dependent?

OR

In SR, does one just observe an increase in mass as a function of its relative velocity?

11) Relative Velocity: In SR, is observed relative velocity a physical velocity (as in if one observes a rocket approaching at 0.1 c is that rocket actually approaching at 0.1 x (299,792,458 meters per second) as measured in the observer’s frame? If so, does that mean that if one observes a rocket heading “east” with relative velocity 0.1 c and observes a rocket heading “west” with relative velocity 0.1 c that the rockets are approaching each other with a physical velocity, as measured by the observer, of 0.2 c?

OR

In SR, is observed relative velocity a just observed velocity (as in if one observes a rocket approaching at 0.1 c, that rocket is not necessarily approaching at 0.1 x (299,792,458 meters per second) as measured in the observer’s frame ?

12) Domain: Can SR be applied if the observer is accelerating and/or not in an inertial frame? Can SR be applied if the observed is accelerating and/or not in an inertial frame? If not for either and yet SR-like effects (e.g., time dilation) are observed for those cases, what theory predicts them?

13) Consistency:
Have the answers given now to the above questions always been the same for SR through the decades? In other words, has the interpretation of SR regarding the above questions ever changed and if so, when (approximately) and how?

Unacceptable Answers

- You don’t understand SR – Fine. Defining the basic constructs should help make it understandable.

- The Questions add to the confusion - Fine. Defining the basic constructs should help avoid the confusion.

- You don’t understand time – Fine. Answer in terms of proper time which is well defined.

- The answer is both physical and “just observed” - The two are defined to be mutually exclusive – saying it’s “both” is an example of the problem that should be resolved.

- Read Prof. XYZ’s book – The problem is the textbooks do not clearly address the questions asked. However, if the book says “SR’s time dilation means that clocks traveling with a relative velocity will accumulate proper time at different rates as a function of that relative velocity”, then fine, copy that as the answer, but all questions for that topic need to be clearly and completely answered.

- Avoidance, ambiguity, vagueness, double talk – This the problem we’re trying to address. Last Modified: Friday, April 10, 2015