Exploring Relativity: The Conundrum of Absolute Rest Frames in a 2D Universe

[Alkatran]

People refuse to accept that there is no 'rest' frame. Maybe I should just start saying "Well the speed of light is the same for everyone, let's take it's frame" Then I'll fall to the ground yelling "DIVION BY ZERO! ARGH! ARGH!"

All comedy aside:
Consider a 2d universe on top of a sphere. When someone is moving very quickly up the left side of the shere, would he see events higher up on the right side of the sphere as happening sooner or later than if he weren't moving? (according to our clearly superior rest frame )

The problem with this is: Is it only his 2d space which is contracted or the 3d sphere's space?

 

[Garth]

There is no absolute or preferred frame in SR. This insight is carried through into GR with the equivalence principle and the conservaton of four-momentum. However GR introduces masses into the pristine flat SR Minkowski spacetime. Such masses may define a 'preferred frame - that which is co-moving with the Centre of Mass/Momentum.

You may be interested in the discussion on the thread about the Cosmological Twin Paradox and the preferred frame endowed to observers by the topology of a closed universe here.

Garth

 

[yogi]

Garth - do I take it that you are of the opinion that the non-rotating Earth centered reference frame is a preferred frame vis a vis the Earth's motion through space.

 

[Garth]

Garth - do I take it that you are of the opinion that the non-rotating Earth centered reference frame is a preferred frame vis a vis the Earth's motion through space.

yogi - IMHO it is that frame co-moving with the centre of mass and momentum of all the matter in the universe, which itself can be identified with the frame co-moving with the surface of last scattering of the CMB in which it is globally isotropic, may be thought of as a 'preferred frame'.

The cosmological twin paradox highlights its importance as that frame with a 'zero winding number'. That is, if two observers meet in a closed Friedmann universe at two events between which one observer has circumnavigated the universe then one will have measured a longer proper time between these events than the other. The observer in the preferred frame defined by cosmological topology, and therefore the distribution of matter in motion in the whole universe, is the member of the set of all such observers who measures the longest proper time separation between such encounters.

Garth

 

[Aether]

On Cosmic Clocks

Special Relativity is based in part on a definition of simultaneity which assumes that there is no such thing as a cosmic clock. If you had a clock that measures cosmic time, then you could compare that to any regular clock that measures proper time, and with a little bit of work you could identify a preferred frame.

So, how sure are you that there is no such thing as a cosmic clock?

 

[ZapperZ]

Special Relativity is based in part on a definition of simultaneity which assumes that there is no such thing as a cosmic clock.

Say what??!

Where exactly is SR based "in part" on the definition of simultaneity? SR is based explicitly on a couple of postulates. It is the consequences of these postulates that there is an issue with "simultaneity". Simultaneity is one of the consequences, NOT the cause, nor the "base". Nowhere in any of these postulates are there any mention of "simultaneity".

Zz.

 

[Aether]

Here Exactly

Say what??!

Where exactly is SR based "in part" on the definition of simultaneity? SR is based explicitly on a couple of postulates. It is the consequences of these postulates that there is an issue with "simultaneity". Simultaneity is one of the consequences, NOT the cause, nor the "base". Nowhere in any of these postulates are there any mention of "simultaneity".

Zz.

Hello Zz,
In Einstein's 1905 paper On The Electrodynamics of Moving Bodies (which may be found here: http://home.tiscali.nl/physis/HistoricPaper/Historic Papers.html), he makes the following statement: "We have to take into account that all our judgments in which time plays a part are always judgments of simultaneous events". Now, to the extent that one of the postulates of SR that you refer to, namely that "the speed of light c is the same in all inertial frames", applies to "judgements in which time plays a part", then the definition of simultaneity is clearly what is ultimately at issue.

 

[ZapperZ]

Hello Zz,
In Einstein's 1905 paper On The Electrodynamics of Moving Bodies (which may be found here: http://home.tiscali.nl/physis/HistoricPaper/Historic Papers.html), he makes the following statement: "We have to take into account that all our judgments in which time plays a part are always judgments of simultaneous events". Now, to the extent that one of the postulates of SR that you refer to, namely that "the speed of light c is the same in all inertial frames", applies to "judgements in which time plays a part", then the definition of simultaneity is clearly what is ultimately at issue.

And he says A LOT more than that too. But it doesn't mean SR is BASED on all that! All you need to do is this: WORK out the formulation of SR, and tell me if at any given point you are forced to assume what a "simultaneous event" is. Just because something is mentioned, it doesn't mean it is based or built on it.

Zz.

 

[russ_watters]

So, how sure are you that there is no such thing as a cosmic clock?

Pretty sure, since all attempts to find it thus far have failed.

 

[Aether]

And he says A LOT more than that too. But it doesn't mean SR is BASED on all that! All you need to do is this: WORK out the formulation of SR, and tell me if at any given point you are forced to assume what a "simultaneous event" is. Just because something is mentioned, it doesn't mean it is based or built on it.

Zz.

OK, if your argument is with how I'm saying this but not with what I am saying, then please show me how you would phrase what I have said. My point is, Zz, that, contrary to SR, there is a preferred frame in our universe.

 

[Aether]

Pretty sure, since all attempts to find it thus far have failed.

Really? How about the observed mass density of the universe for an example?

 

[quantumdude]

OK, if your argument is with how I'm saying this but not with what I am saying, then please show me how you would phrase what I have said.

Speaking for myself: I wouldn't have phrased what you said at all, because what you said is wrong. SR is not based on the denial of a cosmic clock.

The first postulate says that the speed of light is the same for everyone. In the language of simultaneity, that means that if the emission of a light pulse at x₁ is simultaneous with the reading of "t₁ seconds" on someone's clock, and the absorption of the pulse at x₂ is simultaneous with the reading of "t₂" on the same clock, then the quantities will always work out to:

(x₂-x₁)/(t₂-t₁)

no matter whose clock is used. This, by itself, says nothing about a cosmic clock.

The second postulate says that the laws of EM (and the laws of mechanics) and are the same in every inertial frame. Again, no explicit or tacit denial of a cosmic clock here.

It's when you put the two together that you get the prediction of "no cosmic clock". In other words, SR is not based on that idea. Rather, that idea is derived from SR.

My point is, Zz, that, contrary to SR, there is a preferred frame in our universe.

But you have not provided any theoretical or empirical grounds for saying this.

Really? How about the observed mass density of the universe for an example?

Mass density is not an example of a clock.

 

[Aether]

It's when you put the two together that you get the prediction of "no cosmic clock". In other words, SR is not based on that idea. Rather, that idea is derived from SR.

Based on its two fundamental postulates, SR predicts "no cosmic clock". Thank you Zz, and Tom.

But you have not provided any theoretical or empirical grounds for saying this...Mass density is not an example of a clock.

The observed mass density of the universe is a function of cosmic time. Taking Friedmann's cosmological equations (enter GR) as a first approximation to this function yields one example of a cosmic clock. SR's prediction of "no cosmic clock" fails due to the non-zero mass density of the universe, and therefore something is clearly wrong with either one or both of the fundamental postulates of SR in this context. The door is now open to a preferred frame, and our cosmic clock is useful for identifying this frame.

There is no absolute or preferred frame in SR. This insight is carried through into GR with the equivalence principle and the conservaton of four-momentum. However GR introduces masses into the pristine flat SR Minkowski spacetime. Such masses may define a 'preferred frame - that which is co-moving with the Centre of Mass/Momentum..

Published results from the four-year COBE DMR Cosmic Microwave Background (CMB) Observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F9601067 , indicate “… a value for the CMB monopole temperature, T0 =2.725 ± 0.020 K…” and confirm that “The CMB anisotropy is dominated by a dipole term usually attributed to the motion of the solar system with respect to the CMB rest frame…” (e.g., an absolute frame of reference with which to standardize realistic units of space or time). More recently, pre-publication results from the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0302207 indicate that “The WMAP-determined dipole is 3.346 ± 0.017 mK in the direction (l,b)=(263.85º ± 0.1º, 48.25º ± 0.04º)”; which is consistent with a solar system β of 1.228(±0.015)E-3.

 

[ZapperZ]

OK, if your argument is with how I'm saying this but not with what I am saying, then please show me how you would phrase what I have said. My point is, Zz, that, contrary to SR, there is a preferred frame in our universe.

Er... hello? You want ME to put words into your mouth so that I can understand what you are trying to say? What kind of a scam is this?

And since when is physics based on accepting statements of what you or anyone else is saying? Are experimental verifications completely devoid from your consideration? If you think there are contradictions to SR, please cite examples. I, on the other hand, have a zoo of experimental evidence at my disposal. Don't believe me? Check my Journal entries that contains a bunch of published experimental verifications of the postulates of SR and GR.

Zz.

 

[ZapperZ]

Published results from the four-year COBE DMR Cosmic Microwave Background (CMB) Observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F9601067 , indicate “… a value for the CMB monopole temperature, T0 =2.725 ± 0.020 K…” and confirm that “The CMB anisotropy is dominated by a dipole term usually attributed to the motion of the solar system with respect to the CMB rest frame…” (e.g., an absolute frame of reference with which to standardize realistic units of space or time). More recently, pre-publication results from the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0302207 indicate that “The WMAP-determined dipole is 3.346 ± 0.017 mK in the direction (l,b)=(263.85º ± 0.1º, 48.25º ± 0.04º)”; which is consistent with a solar system β of 1.228(±0.015)E-3.

I challenge you to contact the authors who published all the papers on CMB results and the WMAP results and ask them if this is exactly what they meant. I will bet you any amount of money that you have bastardized what they are saying because you clearly do NOT understand the basic principles of SR and GR. I have attended several seminars given by people reporting the WMAP results here at Argonne, and in NONE of them have there ever been any declaration of absolute reference frame of any kind! If this is the case, it would have made the headlines in ALL the major physics journals. Yet, where are they?

You took bit and pieces of snippets of information the very same way the quacks took bits and pieces of understand of "zero point energy" and took off into a completely bogus direction.

Zz.

 

[Aether]

Er... hello? You want ME to put words into your mouth so that I can understand what you are trying to say? What kind of a scam is this?

Since your label says "Science Advisor", I thought that you might be willing to gove me some advice.

Are experimental verifications completely devoid from your consideration? If you think there are contradictions to SR, please cite examples. I, on the other hand, have a zoo of experimental evidence at my disposal. Don't believe me? Check my Journal entries that contains a bunch of published experimental verifications of the postulates of SR and GR.

Zz.

Ok, gravity is a contradiction to SR.

 

[Aether]

I challenge you to contact the authors who published all the papers on CMB results and the WMAP results and ask them if this is exactly what they meant. I will bet you any amount of money that you have bastardized what they are saying because you clearly do NOT understand the basic principles of SR and GR. I have attended several seminars given by people reporting the WMAP results here at Argonne, and in NONE of them have there ever been any declaration of absolute reference frame of any kind! If this is the case, it would have made the headlines in ALL the major physics journals. Yet, where are they?

You took bit and pieces of snippets of information the very same way the quacks took bits and pieces of understand of "zero point energy" and took off into a completely bogus direction.

Zz.

The words absolute reference frame are my own, and they did not come from the authors of those papers on CMB.

And since when is physics based on accepting statements of what you or anyone else is saying?.

So, which is it Zz?

I do not doubt the evidence for SR or GR. With respect to SR, I am simply pointing out that it is only valid in the limit as the volume of the space-time element under scrutiny goes to zero. It simply does not apply to the universe as a whole; not by any stretch of the imagination. However, with respect to GR, I do believe that it is an incomplete theory.

 

[quantumdude]

The observed mass density of the universe is a function of cosmic time.

How's that? "Mass density" is not a Lorentz invariant, so just like time, it is not expected to be the same for all observers. And can you please explain how your argument for cosmic time does not simply presuppose the same? It isn't apparent to me that it doesn't.

Taking Friedmann's cosmological equations (enter GR) as a first approximation to this function yields one example of a cosmic clock.

I'll freely admit that my specialty is particle physics and not cosmology. So, could you please supply some backing details to this statement? Mathematical statements would be preferable.

SR's prediction of "no cosmic clock" fails due to the non-zero mass density of the universe, and therefore something is clearly wrong with either one or both of the fundamental postulates of SR in this context.

This is naive. SR's prediction of "flat universe" fails due to the presence of matter in the universe. Guess what? SR is an approximation. But that does not mean that it is to be discarded in the regimes when it is known to be reliable. And there is nothing "wrong" with the postulates of SR. It's just that they need to be supplemented by the postulates of GR to match all of the observational evidence.

But that's not to say that the predictions of SR don't match a hell of a lot of the observational evidence.

The door is now open to a preferred frame, and our cosmic clock is useful for identifying this frame.

Sorry, but the simple identification of the limits of applicability of SR is not sufficient to open the door to the negation of SR.

Published results from the four-year COBE DMR Cosmic Microwave Background (CMB) Observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F9601067 , indicate “… a value for the CMB monopole temperature, T0 =2.725 ± 0.020 K…” and confirm that “The CMB anisotropy is dominated by a dipole term usually attributed to the motion of the solar system with respect to the CMB rest frame…” (e.g., an absolute frame of reference with which to standardize realistic units of space or time).

In the words of the venerable ZapperZ: "Hello?"

You cannot validly infer that the CMB provides some 'absolute' frame of reference. At least, you have not provided any reason for thinking that you can. Do you have any reasons?

More recently, pre-publication results from the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0302207 indicate that “The WMAP-determined dipole is 3.346 ± 0.017 mK in the direction (l,b)=(263.85º ± 0.1º, 48.25º ± 0.04º)”; which is consistent with a solar system β of 1.228(±0.015)E-3.

And you think this means...?

 

[4newton]

SR does not allow for a preferred frame of reference and therefore it does not apply to the Big Bang.

If you accept the concept that the Big Bang is the starting point of our universe, and there is much evidence to prove that it was, then you must accept the fact that the BB is the prime frame of reference for the entire universe. By every manner of reason the BB is a preferred frame of reference.

To try and use theories of SR and GR, which only deal with a very small part of the nature of the universe, as a reference eliminates any consideration of the rest of the nature of the universe. This is why no connection of gravity to the other forces has been made and no connection to QM is possible.

All observation requires that the BB happen about 15 billion years ago and the universe changed in that time to the universe we see today. All logic requires the acceptance that a transition of the universe took place from the BB to the universe of today. The only question is the nature of the transition.

The nature of the transition of the BB is the starting point and reference for all other frames of reference.

To deny the reality of transition outward from the BB is not logical or productive.

 

[yogi]

All of the experimental results that are cited to support SR are also consistent with LR (Lorentz Relativity), and MLET (modified Lorentz Ether Theory), Non rotating Earth center as a preferred frame, and a frame that has zero velocity with respect to the CBR (a point and velocity where the CBR is isotropic). All experiments that confirm the Lorentz transforms are also consistent with Selleri transforms, and some other cosmological theories. Most of the alternative theories are based upon one of the above preferred reference frames and they all predict the same results as SR. So until there are experiments that fasify these alternative explanations in favor of SR, why be so certain that SR is any more correct than any other theory that gets to the same result vis a vis a preferred reference frame.

 

[4newton]

Yogi:
You are correct.
The BB theory agrees with all experiment or observation and is more logical than all other theories.

If you leave Earth and go to a more massive planet you do not move forward or back in time during the time that you are on the heavy planet. A clock that you take with you will slow down just as it does if you travel at a high velocity, the twin paradox. You may think of this as the mass twin paradox. When you return you always find that your cosmological time has not changed.

Cosmological time is (CT) the time from the BB or (ct) the distance from the BB. This may be considered real time (RT)

If real time changed when you changed position, move with velocity, or change to a higher gravity environment. You would not be able to return to the previous real time. Anyone in the real time that you left would never see you again. This would apply no matter how small your change of time was. Since this never happens there must be only one reality. Also real time (RT) must be the same for all under all conditions.

The same thing applies to the expansion of the universe. Mass has nothing to do with the expansion of the universe. Heavy stars do not transition out from the BB at a rate different than lighter stars. Mass only affects the space around it. The transition from the BB is not a spatial transition. GR only applies to inertia, a mass or gravity function, and does not cover charge forces. GR gives no mechanism for inertia or gravity and therefore has limited usefulness.

The understanding of the universe must start with the BB as an absolute of our universe or a relative absolute of all of creation.

 

[Garth]

Check my Journal entries that contains a bunch of published experimental verifications of the postulates of SR and GR.

Yes but it is those observations that might falsify SR and GR that are important!

For example, we might consider the need to add unidentified Dark Matter and Dark Energy to the standard theory to be examples of where GR may be falling short.

As I posted above, SR is configured for a flat Minkowski space-time, which is empty. Not only do I have no problem with "no-preferred frame of reference" in SR, but also I cannot see how it could be otherwise, as there is nothing "to hang such a frame on".

This principle of 'no-preferred frame' is then carried forward into GR, specifically in the conservation of energy-momentum. This is because the four-momentum of a particle is invariant wrt different frames of reference.

Matter is normally required once gravitational fields are to be discussed. Although universes containing only energy i.e. radiation, or a cosmological constant, or hyperbolic and empty such as the Milne model, can also be considered.

However once matter is introduced, such as in our real universe out there, then there is something "to hang such a frame on". Thus it is possible to identify a unique frame of reference "hung on" the Centre of Mass or centroid of the entire universe. Such a frame might be identified with the globally isotropic frame of the CMB.

The question is, "Is this unique frame 'preferred' in some way? Does it affect local physics?"

As I linked above, the thread on the cosmological twin paradox discusses one particular manifestation of local physics - clock rate - that is affected by the global geometry, at least in a closed universe. This paradox is: Consider two observers in mutual inertial motion that pass each other when they mark their own clocks. After a very long time they meet again, because one has circumnavigated the universe, but which one? The paradox is that, if there is no preferred frame then, each should think it is they that has remained stationary and the other has traveled a great distance. However by comparing clocks they would discover that one has suffered a greater duration between encounters than the other. So it is they that has been ‘stationary’ is some ‘absolute’ sense. Stationary, that is, wrt the matter that has determined the topology of the universe, stationary wrt the surface of last scattering of the CMB for whom the CMB is globally isotropic.

Garth

 

[ZapperZ]

The words absolute reference frame are my own, and they did not come from the authors of those papers on CMB.

Yet, you FREELY used that result to support your argument for no apparent basis. The CMB is NOT an evidence to contradict SR's postulates. This means you have NO experimental evidence. Zilch.

So, which is it Zz?

I do not doubt the evidence for SR or GR. With respect to SR, I am simply pointing out that it is only valid in the limit as the volume of the space-time element under scrutiny goes to zero. It simply does not apply to the universe as a whole; not by any stretch of the imagination. However, with respect to GR, I do believe that it is an incomplete theory.

You can point out anything you wish. So can any fool! What makes this science, and physics in particular is the EXPERIMENTAL EVIDENCE. You have none. Somehow, that makes no difference to you. Luckily, what is in physics does not simply go by what you "believe".

Zz.

 

[ZapperZ]

Since your label says "Science Advisor", I thought that you might be willing to gove me some advice.

Sure.. here's my advice: STUDY PHYSICS FIRST before being so blatantly free about challenging and guessing if anything about it is wrong. Imagination without knowledge is ignorance waiting to happen, as you have clearly illustrated.

Zz.

 

[ZapperZ]

Yes but it is those observations that might falsify SR and GR that are important!

Er.. then FIND them!

I would be the first one with a big glee on my face whenever I find any experimental evidence that contradict any theory. As an experimentalist, I would be lying if I don't admit to having some extra satisfaction in that. And it is why ALL of the experimental evidence that I cited were done - to continually and severely test the basic postulates and consequeces of SR. But the straighforward FACT is, there have beeen NONE! Zilch! Nada!

Now I'm NOT saying there isn't going to be one. But for those who are already establishing ideas that SR and GR are WRONG, I am pointing out that there are ZERO experimental evidence to base such claim on. This is ALL I am trying to say by making that list of experimental evidence. If one is perfectly comfortable with making claims despite of the lack of any physical evidence, then hey, be my guest. If one doesn't care how foolish one looks at making such claims, then why should I?

Zz.

 

[Aether]

How's that? "Mass density" is not a Lorentz invariant, so just like time, it is not expected to be the same for all observers. And can you please explain how your argument for cosmic time does not simply presuppose the same? It isn't apparent to me that it doesn't...I'll freely admit that my specialty is particle physics and not cosmology. So, could you please supply some backing details to this statement? Mathematical statements would be preferable.

Here is some info on cosmological time
http://math.ucr.edu/home/baez/physics/Relativity/GR/hubble.html wherein the author uses both the CMB temperature and average mass density as examples of a cosmic clock.

Instantaneous Lorentz invariance is an ideal property for a cosmic clock reference signal. However, like the temperature of the CMB for example, dipole/multipole anisotropies can be accounted for because the signals are coming at you from every direction in the sky.

This is naive. SR's prediction of "flat universe" fails due to the presence of matter in the universe. Guess what? SR is an approximation. But that does not mean that it is to be discarded in the regimes when it is known to be reliable.

Correction, all of SR's prediction's ultimately fail due to the presence of matter and energy in the universe. That is not to say that it does not have extraordinary value as an approximation tool when handled properly. What it does mean is that thou shalt not extraoplate SR very far beyond the room that you are currently sitting in, let alone across the entire universe, nor across any significant span of time.

And there is nothing "wrong" with the postulates of SR. It's just that they need to be supplemented by the postulates of GR to match all of the observational evidence...But that's not to say that the predictions of SR don't match a hell of a lot of the observational evidence.

All is a prettly strong claim. So, where is the other 97% of the matter and energy that is supposed to be out there?

Sorry, but the simple identification of the limits of applicability of SR is not sufficient to open the door to the negation of SR.

The door is open because SR's prediction of "no cosmic clock" fails.

In the words of the venerable ZapperZ: "Hello?"...You cannot validly infer that the CMB provides some 'absolute' frame of reference. At least, you have not provided any reason for thinking that you can. Do you have any reasons?

I first correctly predicted the magnitude of the CMB dipole anisotropy, to within a set of error bars corresponding to the Earth's orbit about the Sun, using published tables of the ionization potentials of the elements. I then located the published findings from COBE and WMAP. So, if there are any university faculty members out there who would like to privately review my work with a view toward co-authoring one or more papers with me on the subject, I would be interested in speaking with you.

And you think this means...?

I think this means that particle physicists should be aware of the existence and configuration of the CMB rest frame, and should be on the look out for anomalies on the atomic and subatomic scales which might correspond to the existence of an absolute reference frame of the same configuration.

The question is, "Is this unique frame 'preferred' in some way? Does it affect local physics?"

 

[Garth]

Er.. then FIND them!

Zapper I am fully convinced that SR is concordant with experimental testing in a non-gravitational regime.
However I do think there are indications that GR is not holding up:
These are:
1. The need to invoke Inflation to explain the horizon, density and smoothness problems of GR cosmology. Inflation requires the Higgs boson which has not been discovered after thirty years of intensive research. So I would agree with you if you can "find" the Higgs boson!
2. The need to invoke Dark (non baryonic) Matter to make up the energy density of galaxies, clusters and the universe as a whole. Again all attempts to identify this species have so far failed. Again I would agree with you if you can "find" Dark Matter!
3. The need to invoke Dark Energy to make the cosmological density equal to the critical density for the flatness deduced from the WMAP data. Again I would agree with you if you can "find" Dark Energy!
4. The need to explain the lack of the large angle fluctuations in the COBE and WMAP data.

Finally as I posted above and on the thread on the subject the cosmological twin paradox illustrates that the topology of the universe imposes a preferred frame on local physics as far as observers clock rates are concerned. I do consider this to be an inconsistency in the theory.
Garth

 

[ZapperZ]

Zapper I am fully convinced that SR is concordant with experimental testing in a non-gravitational regime.
However I do think there are indications that GR is not holding up:
These are:
1. The need to invoke Inflation to explain the horizon, density and smoothness problems of GR cosmology. Inflation requires the Higgs boson which has not been discovered after thirty years of intensive research. So I would agree with you if you can "find" the Higgs boson!
2. The need to invoke Dark (non baryonic) Matter to make up the energy density of galaxies, clusters and the universe as a whole. Again all attempts to identify this species have so far failed. Again I would agree with you if you can "find" Dark Matter!
3. The need to invoke Dark Energy to make the cosmological density equal to the critical density for the flatness deduced from the WMAP data. Again I would agree with you if you can "find" Dark Energy!
4. The need to explain the lack of the large angle fluctuations in the COBE and WMAP data.

Finally as I posted above and on the thread on the subject the cosmological twin paradox illustrates that the topology of the universe imposes a preferred frame on local physics as far as observers clock rates are concerned. I do consider this to be an inconsistency in the theory.
Garth

I'm not going to argue with you on the validity of GR. It is one of the areas of physics in which there aren't a lot of clear and strong experimental evidence.

On the same note, you need to also look at the points that you brought up as possible "violation" of GR. These so-called "data" required a lot of interpretation and several levels of assumptions. While in terms of degree of certainty, GR isn't one of the high ones, the same could be said about all the observations you are bringing up. It is the NATURE of that field of study in which people still argue if the data is "accurate", "valid", or even if it is saying what people think it is saying. For example, just last week, a paper in PRL introduced the possibility that the low-angle cosmic signal may not even be "cosmic" and could in fact have been generated within our own solar system.[1] Now shouldn't you let these observations and results stew for a little bit longer before jumping into it head first and proclaim them as a done deal? This applies to both camps that support or contradict GR or any theory. When you are dealing with a field of study that inherently already have a problematic degree of certainty, how can one be THAT certain?

Zz.

[1] D.J. Schwarz et al. PRL v.93, p.221301 (2004).

 

[Nereid]

To Aether (and yogi): I'm in the slow class today, would you mind patiently explaining how the CMB(R) can be used to establish an absolute frame of reference? I'm particularly interested in seeing how - in principle! - it could be used to create an absolute ruler and clock, oh, and an absolute set of coordinate directions (orthogonal or not) would be nice, as too would an absolute origin for the coordinate system and clock.

Please be sure to explain why the procedures you describe would yield the same results whether I'm here on Earth, somewhere in the Bootes void, orbiting M87's SMBH (just so I don't get sucked in), or somewhere in the vicinity of one of the primordial galaxies in the HUDF field (z ~=8). {Garth's cosmological paradox method is not permitted; you can't assume anything about the geometry}

 

[Garth]

ZZ

how can one be THAT certain?

I only said

there are indications that GR is not holding up:

How can you be THAT certain that it is?

Neried. Transport yourself into the frame of reference in which the CMB is globally isotropic, locally your frame of reference, and its clock rate has a special property.
I quote from a Barrow and Levin paper "The twin paradox in compact spaces" http://arxiv.org/abs/gr-qc/0101014

In a compact space, the paradox is more complicated. If the traveling twin is on a periodic orbit, she can remain in an inertial frame for all time as she travels around the compact space, never stopping or turning. Since both twins are inertial, both should see the other suffer a time dilation. The paradox again arises that both will believe the other to be younger when the twin in the rocket flies by. The twin paradox can be resolved in compact space and we will show that the twin in the rocket is in fact younger than her sibling after a complete transit around the compact space. The resolution hinges on the existence of a preferred frame introduced by the topology.

As a gedanken: start in the "isotropic CMB" frame with a dense and closed universe. Your clock will record the longest of all proper times of all geodesics between the "twin encounters".
But if the requirement of "no-preferred frames" is mandatory, and not just a requirement of GR, then this case cannot exist and the universe must be open.

However, it could be argued that this restriction is artificial and in fact the real universe might indeed be closed. It would be a matter for observation rather than theoretical prediction and as such a closed universe might be seen as falsifying the theory. Then again Gravity Probe B might be doing just that right now. We shall see!

Garth

 

[jcsd]

To Aether (and yogi): I'm in the slow class today, would you mind patiently explaining how the CMB(R) can be used to establish an absolute frame of reference? I'm particularly interested in seeing how - in principle! - it could be used to create an absolute ruler and clock, oh, and an absolute set of coordinate directions (orthogonal or not) would be nice, as too would an absolute origin for the coordinate system and clock.

Please be sure to explain why the procedures you describe would yield the same results whether I'm here on Earth, somewhere in the Bootes void, orbiting M87's SMBH (just so I don't get sucked in), or somewhere in the vicinity of one of the primordial galaxies in the HUDF field (z ~=8). {Garth's cosmological paradox method is not permitted; you can't assume anything about the geometry}

Thik about FLRW cosmology, we assume that the universe is both homogenous and isotrpic as that is indeed as it appears to be. However hopefully it shouldn't be a major leap to see that there's only going to be one frame in which it is isotropic, so by using the assumption it is isotropic when building our models of the universe we are looking at one frame in particular, which can be defiend by observing the CMBR.

In some sense this frame is special i.e. because it's isotropic, but that does not go against the general principle of relativity as the basic laws of physics are still the same in each frame and the existence of the frame whilst it does allow you to define quite a useful clock and quite a useful distance, doesn't define an absolute clock or absolute distance.

Of cpourse it is fair to question the principle of general relativty, but most cosmologists don't see any conflcit between the existence of this frame and the principle of relatvity.

 

[Garth]

but most cosmologists don't see any conflcit between the existence of this frame and the principle of relatvity.

I do! (Because the isotropic frame has a 'special' local physics - see my last post)

Garth

 

[Aether]

To Aether (and yogi): I'm in the slow class today, would you mind patiently explaining how the CMB(R) can be used to establish an absolute frame of reference?

see: http://www.astro.ucla.edu/~wright/cosmo_04.htm

Published results from the four-year COBE DMR Cosmic Microwave Background (CMB) Observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F9601067 , indicate “… a value for the CMB monopole temperature, T0 =2.725 ± 0.020 K…”.

If you were sitting stationary with respect to the CMB, you would "see" blackbody radiation coming at you from every direction in the sky from which an astute observer could infer this CMB monopole temperature.

“The CMB anisotropy is dominated by a dipole term usually attributed to the motion of the solar system with respect to the CMB rest frame…”

More recently, pre-publication results from the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0302207 indicate that “The WMAP-determined dipole is 3.346 ± 0.017 mK in the direction (l,b)=(263.85º ± 0.1º, 48.25º ± 0.04º)”; which is consistent with a solar system β of 1.228(±0.015)E-3.

The spectrum of blackbody radiation coming from the specified direction is blue-shifted so as to appear 3.346 ± 0.017 mK warmer ($$\frac{v}{c} \cdot T_{0}$$)than the CMB monopole temperature. This Doppler-shift is usually attributed to a velocity of our solar system with respect to the CMB rest frame of approximately 368km/s.

I'm particularly interested in seeing how - in principle! - it could be used to create an absolute ruler and clock, oh, and an absolute set of coordinate directions (orthogonal or not) would be nice, as too would an absolute origin for the coordinate system and clock...Please be sure to explain why the procedures you describe would yield the same results whether I'm here on Earth, somewhere in the Bootes void, orbiting M87's SMBH (just so I don't get sucked in), or somewhere in the vicinity of one of the primordial galaxies in the HUDF field (z ~=8). {Garth's cosmological paradox method is not permitted; you can't assume anything about the geometry}

And would you like any fries with that? But seriously folks, from the classical perspective at least, every particle in the universe already knows, in absolute terms, precisely where it belongs, and precisely what time it is. We're the ones who are having to struggle to figure this thing out.

Anyway, once you have measured the temperature of the CMB monopole (currently 2.725 ± 0.020 K) and dipole with respect to your own inertial frame (3.346 ± 0.017 mK), then you can use the dipole temperature to determine your absolute velocity with respect to the CMB rest frame:

$$\frac{0.003346K}{2.725K} \cdot c \approx 368 \frac{km}{s}$$.​

To make a cosmic clock, you need a function that gives cosmic time as a function of the CMB monopole temperature. The WMAP team has estimated that

$$2.725K \approx 13.4 Gyr$$.​

 

[Garth]

And the cosmic clock, measuring t cosmological time since the Big Bang, is in fact a thermometer measuring the CMB monopole temperature T (degrees K) with
t = 13.4 x 2.725/T Gyr.

Garth

 

[Nereid]

Thanks everyone (so far).

I understand that it is possible to determine one's velocity (speed and direction) wrt the CMBR, at least here on Earth. No one has yet shown (jcsd aside, but only in general terms) that this determination is independent of one's current position in the universe (if I'm orbiting the M87 SMBH, can I make the same determination? Is the result of that determination the same as the one I make from here on Earth? What about if I'm near one of those really distant HUDF galaxies?).

Of course, I will measure my velocity wrt the CMBR in terms of my local rulers and clocks, and can convert to xc (0 <= x < 1) - but how do I then get an absolute ruler and clock? And (esp Aether) - if my clock is calibrated by the apparent age of the universe (from where I am), can you show that a) this is (cosmology) model independent, and b) the same no matter where I might be?

I also see that no one has tried to give me an in principle way to determine the (absolute) origin and directions of any (spatial) axes.