1 Why there must be an absolute frame - New Book

On 7/8/17 7/8/17 7:05 AM, Edgar L. Owen wrote:

>	Relativity is well known for saying that all frames are equally valid and there is no absolute frame but this is demonstrably false.

No it isn't "false", it's just that you don't understand what relativity ACTUALLY says.

>	1. Rotation is with respect to an absolute frame roughly aligned with the aggregate mass of the universe. Google 'Newton's Bucket' or 'Mach's Principle'.

Not true. Rotation is relative to local inertial frames. These frames are "special" in that they reflect a symmetry of the world we inhabit; they are not in any way "absolute".

For example, Gravity Probe B demonstrated its local inertial frame [#] is rotating relative to the distant "fixed" stars. And it is rotating at the rate predicted by GR as induced by the rotation of the earth.

[#] In the sense of GR, not SR.

>	2. Each of the space traveling twins moves equal and opposite to the frame of the other but only one's clock time actually ran slower though both observed each other's clock time run slower during the movement.

The point is that one twin remains at rest in an inertial frame and the other doesn't. You need to learn what SR actually says, and how it applies.

>	Thus there are ACTUAL relativistic effects, and OBSERVATIONAL relativistic effects. A critical distinction not recognized by relativity itself.

You attempt to make a distinction without a difference.

>	[... further nonsense based on the above errors]

You REALLY need to learn what relativity ACTUALLY says -- your GUESSES are wrong.

Tom Roberts

2 Why there must be an absolute frame - New Book

Hmmm. Here on earth, gravity seems very "appreciable" to me. And we _DO_ orbit the sun, with a corresponding acceleration....

But compared to an observer moving at "near light speed", those are negligible.

"Appreciable" is the wrong word; here "negligible" is the right one.

>	Both A and B see each other's clocks running slower than their own by equal amounts. This is an OBSERVATIONAL relativistic effect. However only observer B's clock is actually running slower. This is the ACTUAL relativistic effect.

This is simply not true. NEITHER clock is "actually running slower", because each one ticks at its usual rate.

As I said before: you REALLY need to learn what relativity _ACTUALLY_ says. Your GUESSES are wrong.

Note that many/most elementary books on SR take a verbal shortcut to get the basic point across. Any book that claims "moving clocks run slow" is WRONG -- get a better book. I suggest: Taylor and Wheeler, _Spacetime_Physics_.

In essence you have ASSUMED some sort of "absolute" frame for the earth observer A. That's completely invalid in SR. And downright silly, as the earth is CLEARLY not at rest in any inertial frame (much less some fictitious "absolute" one).

>	[... further nonsense based on that error]

Note that rotation is not "absolute" as you claim. Gravity probe B showed its local inertial frame is rotating relative to the "fixed stars", and that its rotation is consistent with the GR prediction for being induced by the rotating earth. In the world we inhabit, rotation _IS_ relative to locally inertial frames.

You claim to have written a book on this -- that's a total waste of time (both yours and any reader's), as it is clear that you do not understand the fundamental concepts and vocabulary of very basic physics.

Would you bother with a math book that claims to present "A whole new way to do advanced calculus" written by someone who does not understand elementary arithmetic?

Tom Roberts

3 Why there must be an absolute frame - New Book

Then why do you keep making statements in conflict with relativity? Including below.

You have deluded yourself into thinking you understand it, when in fact you do NOT.

>	And in fact i again have to correct your false assertion that rotation is relative to an inertial frame when it's actually absolute as can be easily Googled.

Google is IRRELEVANT for technical questions like this.

"Truth is not established by pooling ignorance." - Ayn Rand

>	There is a long history of trying to understand what rotation is relative to and more importantly WHY going back to Newton's bucket and Mach's Principle, and current physics still hasn't been able to come up with an answer.

NONSENSE! GR certainly has the answer: the rotation of a given object is relative to any locally inertial frame.

>	Of course rotation is largely with respect to the aggregate mass of the universe

Not in GR. Note that GR only implements a pale shadow of Mach's principle [#]: the geometry at any given point depends on the distribution of mass and energy throughout the universe. This of course includes the set of locally inertial frames. As one might expect, nearby mass and energy are more important than those that are far away. Note in particular that the mass of any object is completely unrelated to anything else in the universe (in contradiction to the usual statement of "Mach's principle").

NONSENSE! GR provided a complete and compelling answer in 1916: rotation is relative to any locally inertial frame.

If you truly understood relativity, you would know this.

>	Sadly you are also dead wrong that the moving space traveler's clock isn't actually slowed down. That is a basic fact of relativity [...]

Again you show that YOU DO NOT UNDERSTAND RELATIVITY.

For any object, its elapsed proper time between points A and B on its worldline is:

Note this same equation applies to the length of an arbitrary path in Euclidean geometry. For this, all that differs between Euclid and GR are the dimension of the manifold and the metric.

>	That's why the traveler has aged less when he returns to earth. This is relativity 101.

No. Not even close. You obviously flunked relativity 101.

A "clock slowing down" cannot be the reason, because CLOCKS NEVER SLOW DOWN. The correct explanation of the twin paradox is that the elapsed proper time for the two twins differs between their separation and reunion [@]. Just like two sides of a triangle have a larger total path length than the third side -- the odometer does not "slow down", the PATHS HAVE DIFFERENT LENGTHS. In relativity, the path length of a timelike path is its elapsed proper time. Note that the usual twin paradox with instantaneous accelerations is just a triangle in a space-time plane [%].

[@] Proof: the calculation of the elapsed time of each twin's clock between meetings A and B uses precisely the equation given above, applied separately to each twin's trajectory. No "clock slowing down" is present, but different path lengths (elapsed proper times) are manifest.
[%] The geometry of a space-time plane is hyperbolic, which is why the two legs of the traveler have shorter path length than the single leg of the home twin.

>	Do you also believe that a clock in an intense gravitational field isn't actually slowed down?

It's not what I "believe" that matters, it's WHAT GR PREDICTS -- no clock is ever "slowed down". It's just that different timelike paths through spacetime can have different elapsed proper times between intersections. This includes clocks in gravitational fields, the twin paradox, etc.
If you truly understood relativity you would know this.

>	So I understand relativity quite well, [...]

No, you DON'T. You don't even know enough to recognize your own errors. And your delusion is strong enough that you cannot even recognize your own errors when they are explained to you. How sad.

Tom Roberts

4 Why there must be an absolute frame - New Book

Don't bother. You have demonstrated quite clearly that you do not understand relativity. So I have no interest in your ramblings and word salad.

History shows that people who do not understand current theories and experiments of physics have NO HOPE of making useful contributions to the field. So if you want to contribute, first you must STUDY. If you actually do that, you'll surely find that most if not all of your current notions are simply wrong.

Tom Roberts

5 Why there must be an absolute frame - New Book

Sadly your last two long posts are full of misunderstandings and misrepresentations of relativity.

Let me cut to the core issues and ask you two simple questions which hopefully you can give concise answers to without descending into obsessive name calling..

1. Do you actually believe that the clock of the space traveling twin isn't running slower than that of the stay at home twin? Even school kids know it is.

2. You claim rotation isn't absolute but relative to a local inertial frame. But you totally missed my simple explanation that accelerations of all types are absolute because they can be felt by the accelerating object itself. Do you actually deny that an acceleration can be felt by the accelerating object itself? That's precisely what makes accelerations including rotation absolute.

If you get these wrong then you not only don't understand relativity, you don't even understand Newtonian physics....

Edgar L. Owen

6 Why there must be an absolute frame - New Book

Nope. The mistakes and misunderstandings are YOURS. Your #1 is definitely your personal misunderstanding of relativity; your #2 could be argued to be just about words. In both cases, a major part of your problem is reliance on sound bytes that are incapable of capturing the details, and thus turn out to be wrong.

>	1. Do you actually believe that the clock of the space traveling twin isn't running slower than that of the stay at home twin? Even school kids know it is.

Again, it's not what I "believe" that is at issue, it's what relativity predicts. Relativity UNAMBIGUOUSLY and DEFINITIVELY predicts that the traveling twin's clock runs at its usual rate, and is MOST DEFINITELY NOT "running slower" than any other identical clock -- identical clocks ALWAYS run at identical rates. That is what "identical clocks" MEANS.

Anybody who thinks the traveling twin's clock is "running slower than the home twin's clock" is WRONG, including "school kids", AND YOU.

Basically you have assumed that "running slower" is ALWAYS a comparison to the home twin's frame, or perhaps relative to some "absolute" frame. THIS IS COMPLETELY WRONG (indeed it is nonsensical in relativity). You also need to understand basic English usage:
When you say "this clock is running slow", you are discussing THE CLOCK ITSELF, and NOTHING ELSE. The clock ITSELF runs at its usual rate. This _IS_ what that phrase means, and how it applies in relativity.
When you say "this clock runs slower than that clock", you are comparing the two clocks' INTRINSIC rates. But since the clocks are identical, their intrinsic rates are identical. This _IS_ what that phrase means, and how it applies in relativity.

A correct statement about this situation is: the traveling twin's clock IS MEASURED to run slower than the time coordinate of the home twin's inertial frame, when measured in the usual way. (The home twin's clock displays that time coordinate.)

As I have said, your claims are wrong on two levels: English phrasing, and physics.

>	2. You claim rotation isn't absolute but relative to a local inertial frame. But you totally missed my simple explanation that accelerations of all types are absolute because they can be felt by the accelerating object itself.

The basic problem is that you are not precise enough about what you mean by "rotation". HERE THERE BE DRAGONS.

The conventional meaning of "absolute rotation" is relative to the "fixed stars". There is no doubt that this is what Mach meant. The issue is that this is NOT good enough.

The rotation of Gravity Probe B's physics package cannot be "felt" by the package (because it is always at rest in a locally inertial frame). Yet it is ROTATING relative to the "fixed stars" -- i.e. it has nonzero "absolute rotation".

If you claim that since GPB;s package's rotation cannot be "felt", it is zero "absolute rotation", then YOU are using locally inertial frames as the standard for zero "absolute rotation" -- that is decidedly non-standard for that phrase.

>	Do you actually deny that an acceleration can be felt by the accelerating object itself? That's precisely what makes accelerations including rotation absolute.

You are just arguing about words. The word "absolute" has such terrible historical connotations that IMHO it should be avoided completely; "absolute rotation" is even worse, as its standard is clearly inappropriate. The phrase "absolute rotation" has a meaning DIFFERENT from what you seem to want to use.

GPB's package cannot "feel" its "absolute rotation", but it definitely has nonzero "absolute rotation", for the normal meaning of that phrase.

Tom Roberts

7 Why there must be an absolute frame - New Book

Hopeless. Because YOU do not understand relativity.

>	Your saying that rotation is relative to a local inertial frame doesn't solve the question of what rotation is relative to. It just begs that question and so is completely irrelevant.

Nonsense. "Locally inertial frame" is unambiguous and well defined. One can ALWAYS perform experiments to determine a locally inertial frame in any given (small) region of spacetime.

On the contrary, your "aggregate mass of the universe" cannot be determined or measured at all. In particular, the "fixed stars" are most definitely not fixed.

More NONSENSE. YOU do not understand the issue. See my recent post in this thread. I know what Mach's principle is, and also that it is not definitive (he made dozens of statements that differ in details); I also know that GR does NOT implement any of them. But YOU seem to have serious misconceptions here. In particular, the "fixed stars" are now KNOWN to not be fixed, but they are what Mach (and Newton) meant.

Gravity Probe B's physics package is always at rest in a locally inertial frame, which means its rotation cannot be "felt". Yet it is rotating "relative to the aggregate mass of the universe".

>	And WHY a frame that ISN'T rotating or otherwise moving relative to the aggregate mass of the universe IS inertial?

But GPB's physics package is MANIFESTLY at rest in a locally inertial frame, and is MANIFESTLY rotating "relative to the aggregate mass of the universe".

>	This is the basic unsolved problem of relativity [...]

Nope. In relativity, rotation is always relative to locally inertial frames. Your attempt at a "solution" is HOPELESS, and is really a regression to already discredited notions of "absolute rest".

Tom Roberts

8 Why there must be an absolute frame - New Book

I see that I forgot the most damning aspect of "absolute" in this context:

When one says "acceleration is absolute", that implies that the VALUE of the acceleration is the same to everybody -- an important aspect of the concept "absolute". This is blatantly not true: for a given accelerating object, different (locally) inertial frames measure different values for its acceleration, in both magnitude and direction.

Tom Roberts

9 Why there must be an absolute frame - New Book

Statements of fact are not insults. You do not understand GR, and most of what you write is nonsense. Those are facts you refuse to address.

Had you claimed some new theory of your own, I would merely ignore your silliness. But you claim to be "describing GR", which is BLATANTLY FALSE.

>	1. What makes a local inertial frame inertial? A frame is inertial if it isn't rotating (or otherwise accelerating). But what is it NOT rotating or accelerating with respect to?

If you actually understood GR you would already know the answer, as this is very basic.

In this context, a given pointlike object is not accelerating if its 4-acceleration is zero. Equivalently, it is not accelerating if its proper acceleration is zero (proper acceleration is the usual acceleration with respect to the object's instantaneously co-moving locally inertial frame).

Neither 4-acceleration nor proper acceleration are "with respect to" ANYTHING -- they are both independent of coordinates [#]. An object's proper acceleration is what it "feels".

You repeatedly claim to understand GR, but practically everything you write shows that you do NOT.

>	You seem unable to even recognize this fundamental problem, much less answer it.

In GR that IS NOT A PROBLEM. See above. No "reference" is needed. But since you don't understand GR, you remain mystified.

>	2. Is the space traveling twin's clock actually running slower than the stay at home twin's clock?

No. But see my earlier remarks for what these words mean.

>	of course it very clearly is because it's moving faster with respect to the background fabric of space,

NONSENSE! In GR there is NO SUCH THING as "background fabric of space", and if you understood GR you would know this.

That is NOT evidence of "ticking slower", that is evidence of DIFFERENT PATH LENGTHS THROUGH SPACETIME.

Tom Roberts

10 Why there must be an absolute frame - New Book

Moreover, in general such a "grid" is simply not possible -- the geometry of GR admits such a global coordinate system only in certain special situations, most if not all of which are unphysical. And only in a completely empty universe is that "grid" rectangular.

Tom Roberts

11 Why there must be an absolute frame - New Book

But how do you know that clocks are identical? IMO generally speaking by performing an experiment. By preference the most simple experiment as possible, that IMO means you compare the clocks under identical conditions for all. Of course our first assumption should be that all the clocks are build using the same mechanical drawing. When the clocks are build we place them all on a table in front of us and we start them all at the same instant. After one year we come back and we compare the clock reading. Most probably they do not all show the same time. Is it now wrong to say that some clocks run faster and some clocks run slower (compared to one)?

>	A correct statement about this situation is: the traveling twin's clock IS MEASURED to run slower than the time coordinate of the home twin's inertial frame, when measured in the usual way. (The home twin's clock displays that time coordinate.)

Sorry, I do not fully understand this sentence. Generally speaking what I understand are experiments. To understand more we should perform slightly different experiments. We could perform the following experiment. In the first step we make and test 10 clocks and adjust them such that after 1 year they all show the same reading. In step two we place 9 clocks all in different cars, airplanes or spaceships. Next we start all the clocks and all the engines at the same instant. Now all the clocks will travel at different speeds. After one year they will all return back home and placed all side by side. My expectatation is that all the clocks will show a different reading. Is it now wrong to claim that some clocks run slower and some run faster? And what is the explanation? IMO the explanation is something physical. A different question is: is it possible by making certain additional measurements to calculate in advance what the outcome of this experiment should be?

My problem is when we write "IS MEASURED" we should describe how this measurement is performed i.e. WHAT is measured. In the above the only thing that is mesured are clock readings (ticks)

A different problem is when we write "time coordinate" we also have to describe what we mean and how it is measured. The sentence "is measured in the usual way" raises the same issues.

Nicolaas Vroom

12 Why there must be an absolute frame - New Book

For instance, in the GPS system, atomic clocks are used, which are stable to +/- 1 second in 128 million years.

>

When the clocks are build we place them all on a table in front of us and we start them all at the same instant. After one year we come back and we compare the clock reading. Most probably they do not all show the same time. Is it now wrong to say that some clocks run faster and some clocks run slower (compared to one)?

For sure, they will be off perhaps 1 second in 128 million years!

> >	A correct statement about this situation is: the traveling twin's clock IS MEASURED to run slower than the time coordinate of the home twin's inertial frame, when measured in the usual way. (The home twin's clock displays that time coordinate.)

>

Sorry, I do not fully understand this sentence. Generally speaking what I understand are experiments. To understand more we should perform slightly different experiments. We could perform the following experiment. In the first step we make and test 10 clocks and adjust them such that after 1 year they all show the same reading. In step two we place 9 clocks all in different cars, airplanes or spaceships. Next we start all the clocks and all the engines at the same instant. Now all the clocks will travel at different speeds. After one year they will all return back home and placed all side by side.

This is exactly what Hafele and Keating did (the flew 4 atomic clocks and compared them with 1 clock which did not fly).

>	My expectatation is that all the clocks will show a different reading. Is it now wrong to claim that some clocks run slower and some run faster? And what is the explanation?

13 Why there must be an absolute frame - New Book

No, it is NOT a good question. He answers his first question INCORRECTLY. (And he then claims circularity, which HE introduced in the first place.) The correct answer to his first question makes his second question IRRELEVANT.

A frame is (locally) inertial if it is a set of coordinates such that when the metric is projected onto them the components are those of Minkowski: diag(1,1,1,-1). There is NO NEED AT ALL to claim it is "not rotating with respect so something", because it is INERTIAL. In GR such locally inertial frames are the standard for "not rotating". Any such frame is, of course, not rotating or rotating with respect to ANY other such locally inertial frame in its region.

>	Edgar, many folks have dropped into this board, attempting to educate Mr. Roberts re relativity. All solid thinkers and analysts like yourself, but alas, to no avail.

Nonsense! (Or your sarcasm goes unnoticed in this medium.)

>	For instance, we know that light always travels at constant speed c through the background fabric of space,

No, "we" don't "know" that at all!

What we do know is that in vacuum light always travels with speed c relative to ANY LOCALLY INERTIAL FRAME.

Tom Roberts

14 Why there must be an absolute frame - New Book

Part of the problem is linguistic: one cannot discuss "acceleration" in the abstract, as you attempt to do, one can only discuss the acceleration OF A SPECIFIC OBJECT.

In GR, the FACT is that there is no such "problem", except that the bare word "acceleration" is ambiguous -- in GR there are three different quantities that use that word. But your so-called "problem" is non-existent, because each of them has a clear and definite reference:

• proper acceleration, which is what a person feels, is relative to the instantaneously co-moving locally inertial frame of the object.
  
• coordinate acceleration, which is rather artificial, is just d^2r/dt^2, where r is the spatial position of the object expressed in the coordinates, and t is the time coordinate. This is "artificial" in the sense that coordinates are completely arbitrary, so one cannot tell if it is the object or the coordinate system that is actually accelerating (any meaning).
• 4-acceleration, which is dU/d\tau, where U is the object's 4-velocity and \tau is its proper time. This is a 4-vector, so it is a geometrical object completely independent of coordinates. Remember that U is the tangent 4-vector to the object's worldline, and \tau is path length along its worldline (i.e. what its clock measures), so this is well-defined without any need for a "reference".
  [Of these, only 4-acceleration can appear in valid models, because such models must be independent of coordinates.]

Newton and Mach are IRRELEVANT, as we are discussing GR and they had no knowledge of it (it is silly of you to even mention them in this context). Einstein's writings before 1916 are likewise irrelevant.

>	Sorry but I'm siding with Newton, Mach, and Einstein on this rather than you no matter how many times you tell us what a great GR guru you are.

This is not "me telling you", this is WHAT GR ACTUALLY SAYS. And I repeat: YOU DO NOT UNDERSTAND GR.

>	You should really try to at least understand this issue which is fundamental to GR

But IT IS NOT -- it is PURELY a figment of YOUR imagination and misunderstanding.

>	Only when you at least understand what you DON'T know about GR will you have any hope of eventually understanding it....

It is YOU who does not understand GR, and YOU who does not know what you don't know about GR.

Why do you think that you cannot find your "new explanation" in any textbook? -- BECAUSE IT IS WRONG.

I repeat my challenge: show us any mention of an "absolute frame" in any standard GR textbook. Popularizations and comic-books do not count.

Tom Roberts

15 Why there must be an absolute frame - New Book

Yes, I suppose so, in the context of abstract PHILOSOPHY.

But Owen claims to be discussing GR, and in the context of GR this is NOT a problem, because each of the three types of acceleration either has a definite reference (proper acceleration, coordinate acceleration), or has no need of one (4-acceleration).

>	We just don't have a very good resolution of it yet.

In the context of PHILOSOPHY, I suppose so. But in the context of GR there is no need of "resolution", as the "problem" is in OWEN'S MISUNDERSTANDING, not in GR itself.

Much of the problem is linguistic; see my recent post in this thread.

>	I only consider myself guru for people who are totally ignorant. For others I simply post what I do know. From what I've seen of Tom's postings he also writes plainly when he does not know something (a trait completely absent in cranks).

Yes.

>>	[JanPB and I] completely disagree on this fundamental GR issue.

If you actually READ what JanPB and I write, you'll find we don't disagree, we merely discuss issues from somewhat different perspectives. Sometimes we use different contexts (JanPB uses the context of philosophy above, while I use the context of GR).

>	I'll let Tom elaborate. I thought he wrote specifically that the referent for rotations did exist but it wasn't what you thought it was.

Attempting to discuss this in the abstract has thorns. But I can be precise and specific:

In the context of GR: any object at rest in some locally inertial frame is neither rotating nor accelerating in any way [#]. Any object not at rest in any locally inertial frame is accelerating (which includes rotating). IOW: an object is accelerating if its 4-acceleration is nonzero; it is not accelerating if its 4-acceleration is zero. IOW: an object is moving inertially iff its 4-acceleration is zero.

[#] Gravity Probe B shows that locally inertial frames can be rotating relative to ANY "absolute frame" one might imagine. They can also be rotating relative to the "fixed stars" of Newton and Mach -- but of course neither of them had any knowledge of GR.

So in that sense, rotation and acceleration are relative to locally inertial frames. There CLEARLY is no need for any sort of "absolute frame" as Owen fantasizes. GR, of course, has no such thing.

But there are manifolds in which a particular set of coordinates is unique in expressing the symmetries of the manifold (Killing vectors). Note that the FLRW manifolds at the base of modern cosmological models are indeed such manifolds.

Tom Roberts

16 Why there must be an absolute frame - New Book

> >

We could perform the following experiment. In the first step we make and test 10 clocks and adjust them such that after 1 year they all show the same reading. In step two we place 9 clocks all in different cars, airplanes or spaceships. Next we start all the clocks and all the engines at the same instant. Now all the clocks will travel at different speeds. After one year they will all return back home and placed all side by side.

>	This is exactly what Hafele and Keating did (the flew 4 atomic clocks and compared them with 1 clock which did not fly).

17 Why there must be an absolute frame - New Book

In the physical situation being discussed, which is a gedanken, they were stipulated to be identical. In the real world we determine that clocks are identical by comparing their construction.

Of course a clock has an intrinsic accuracy, and multiple identical clocks do not track EXACTLY with each other, but they do so within their stated accuracies.

>>	A correct statement about this situation is: the traveling twin's clock IS MEASURED to run slower than the time coordinate of the home twin's inertial frame, when measured in the usual way. (The home twin's clock displays that time coordinate.)

>	My problem is when we write "IS MEASURED" we should describe how this measurement is performed i.e. WHAT is measured.

This has been beaten to death, here and elsewhere. Go look it up.

Tom Roberts