Do we need a new theory of gravity?

November 9, 2015 by Dr Tessa Baker, Oxford Science Blog, Oxford University

In the late 1990s physicists discovered, to their consternation, that the expansion of the universe is not slowing but accelerating. Nothing in the 'standard model of cosmology' could account for this, and so a new term was invented to describe the unknown force driving the acceleration: dark energy.

We really have no idea what '' is, but if it exists it has to account for about 70% of the energy in the whole . It's a very big ask to add that kind of extra component to the standard cosmological model. So the other explanation is that we are using the wrong equations – the wrong theories of gravity – to describe the rate of the universe. Perhaps if it was described by different equations, you would not need to add in this huge amount of extra energy.

Alternative gravity is an answer to the dark energy problem. Einstein's theory of general relativity is our best description of gravity so far, and it's been very well tested on small scales; on the Earth and in the solar system we see absolutely no deviation from it. It's really when we move up to the very large distance scales involved in that we seem to need to modify things. This involves a change in length-scale of about 16 orders of magnitude (ten thousand trillion times bigger). It would be astounding if one theory did cover that whole range of scales, and that's why changing the theory of gravity is not an insane idea.

One of the real challenges in building theories of gravity is that you need to make sure that your theory makes sense at the very large cosmological scales, without predicting ludicrous things for the solar system, such as the moon spiralling into the earth. I don't think enough of that kind of synoptic analysis gets done. Cosmologists tend to focus on the cosmological properties and they don't always check: does my theory even allow stable stars and black holes to exist? Because if it doesn't, then you need to throw it out straight away.

Over the past decade hundreds of researchers have come up with all sorts of ways to change gravity. Part of the problem now is that there are so many different theories that if you were to test each one individually it would take forever. I've done a lot of work on trying to come up with unified descriptions of these theories. If you can map them all onto a single mathematical formalism, all you have to do is test that one thing and you know what it means for all the different theories.

In doing this mapping process we've discovered that a lot of the theories look very different to start with, but at the mathematical level they're moving along the same lines. It suggests to me that people are stuck in one way of thinking at the moment when they build these gravity theories, and that there's still room to do something completely different.

More recently I've moved on to developing ways to actually test the mathematics – to constrain it with data. For example, we can use gravitational lensing. If you have a massive object like a galaxy cluster, the light from objects behind it is bent by the gravity of the cluster. If you change your theory of gravity, you change the amount of bending that occurs. Basically we throw every piece of data we can get our hands on into constraining these frameworks and testing what works.

At this precise moment the data we have is not quite good enough to distinguish between all the different gravity models. So we are doing a lot of forecasting for the next generation of astrophysics experiments to say what kind of capability will be useful in terms of testing theories of . There's still time in some of these new projects to change the design, and I hope to see some of these experiments come on line.

I am very grateful to my former supervisor Pedro Ferreira, who nominated me for the 'Women of the Future' award, and to the Women of the Future scheme. There are two sides to this award; one is the scientific work itself, and the other is the female leadership aspect. In the interview for the award we had quite an extensive discussion about the role of women in science, and what challenges they face. It's a global field-wide issue, and it is changing; it's just going to take time. And in fact Oxford Astrophysics is brilliant for women: Jocelyn Bell Burnell, Katherine Blundell, Joanna Dunkley – they're all really strong female role models.

Explore further: May the fifth force be with you

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Seeker2
3.5 / 5 (4) Nov 09, 2015
Identify the gravitational potential, or space-time curvature, with the pressure of the dark energy. Gradients in this pressure causes the effects of what think is dark matter - spacetime curvature. Allow these gradients to occur naturally on a cosmological scale without the presence of matter. So then how do we explain the effects of matter on spacetime curvature? Matter displaces dark energy. Therefore the pressure of the dark energy is less in regions containIng matter than it is in regions not containing matter. For example the earth displaces lots of dark energy. So the density of dark energy outside the earth is much greater than that inside earth.
Seeker2
3.5 / 5 (4) Nov 09, 2015
Actually matter displaces the space containing the dark energy. So there is more dark energy outside the earth pressing down on the earth than inside the earth pressing outwards. The result is another gradient in the gravitational potential - what we feel as gravity. So space-time curvature appears naturally on a cosmological scale or in the presence of matter. Actually entropic gravity which emerges from gradients in the pressure of the dark energy. Note – no dark energy, no gravity, the universe falls apart. That's probably why we need so much dark energy.
Urgelt
2.6 / 5 (10) Nov 10, 2015
I'll probably get egg on my face for saying this, but I think the author is barking up the wrong tree. Gravity works just as Einstein said it would. That's probably not where we'll find an explanation for the apparent accelerating expansion of the universe.

I have to wonder why physicists are so resistant to even considering the set of ideas proposed at U Georgia by Edward Kipreos. We know there's *something* wrong or incomplete with theory. Kipreos proposed a solution. Why not test his ideas experimentally?

Kipreos suggests that Special Relativity (SR) may have flaws.

- Its reciprocal time dilation means we do not adjust cosmological observations for time dilation at all, since it's presumed to cancel out. But there is no experimental evidence for reciprocal time dilation. If it should be directional, then our cosmological measurements need a do-over.
Urgelt
2.8 / 5 (10) Nov 10, 2015
- Assuming directionality, Kipreos evaluated a sampling of Type Ia supernovae. Result: the universe is expanding at the rate of Einstein's cosmological constant. Dark energy isn't needed.

- If SR's time dilation should be directional, it has strange implications. One of the implications is that there must be a universal frame - a frame of reference where position in time and space isn't relative at all, but absolute. This does *not* mean that the speed of light in a vacuum isn't a constant. Time dilation still operates to keep the speed of light fixed, relative to any observer anywhere.

Admittedly, Kipreos is coming at the problem of dark energy from a strange direction. Admittedly, it's difficult to believe that Einstein could have been so wrong about SR. But it's not stranger than trying to cook up new theories of gravity, when Einstein's General Relativity pretty much nails it by every measure we can bring to bear. Whereas SR's reciprocity remains untested.
Mimath224
3 / 5 (3) Nov 10, 2015
In my simplistic layman way of thinking accelerating on the macro scale surely needs a hefty 'push' or a hefty 'pull' from something or somewhere. I don't recall reading that anyone has found something 'behind' us with a massive amount of energy (apart from the inflation models) so it seems to me that we are left with a 'pull'. Macro 4D space might have stronger gravity (according to some math models) but then wouldn't we enter 4D space at some point and some researcher might record very odd readings? Gee, I'd hate to think we were being dragged towards a 4D BH, assuming both exist, of course. Would another alternative be that our universe might be 'riding' a 'wave'?
slash
3.4 / 5 (5) Nov 10, 2015
@Urgelt: This theory has been discussed and debunked, e. g. here:
http://physics.st...dilation
theon
4.2 / 5 (5) Nov 10, 2015
Modified gravity theories get ruled out by big galaxy clusters. They are in the Newton regime except in the outskirts. It was Zwicky who ruled out Newton per se, there must be dark matter. A modified Newton gravity theory that works as a Newton theory for most of the cluster is ruled out by Zwicky as well.
katesisco
2.1 / 5 (7) Nov 10, 2015
Well, with V Zarkova's theory of a dynamo underneath a dynamo in Sol, it seems to settle the matter that our system is uniquely different. As I have suggested, our sun was a red giant which I call the Beetle Sun, which was imploded by a massive magnetic grip to Sol and in doing so the off loaded 'dirty gases' created the rocky planets inside the former space of the Beetle Sun. The Oort shell is still very much in existence and whats more science notes that there are other 'hard edged' magnetic shells in our universe.
A science site is : Miles Mathis dot com
Urgelt
2.4 / 5 (9) Nov 10, 2015
Slash: That's a really bad argument.

- It presumes that because GPS time dilation is dominated by GR, we can ignore the SR component.

- It explains the departure from reciprocity for GPS as the product of acceleration and dominant GR effects, but this explanation doesn't confirm SR's reciprocity in the absence of acceleration or GR effects.

- You *can't* confirm reciprocity without empirical evidence. You can posit theories, which is what Einstein did, but no theory can be considered confirmed or debunked without evidence.
MaxwellsDemon
2.8 / 5 (9) Nov 10, 2015
It would be very helpful to have far more precise measurements of the dark energy effect. Currently we have a generic estimate for the magnitude of dark energy acceleration per unit distance on the cosmological scale, and we're assuming that it's an isotropic acceleration field. But we don't actually know that for a fact. It's possible that dark energy is a force acting upon matter at cosmological distances, rather than a (conceptually) simple spacetime expansion effect. Crucial mediating factors could be getting obscured by the huge scales and the small magnitude of the acceleration. It'll take a clever trick to map dark energy as precisely as we're now mapping dark matter, but we must set precise upper limits on any anisotropies so we can see if any factors modulate the dark energy effect at all. The current explanation of a uniform field that drives its own expansion runs counter to everything we've learned about all of the other forces of nature.
Urgelt
2.3 / 5 (8) Nov 10, 2015
"The current explanation of a uniform field that drives its own expansion runs counter to everything we've learned about all of the other forces of nature."

Yes, which is one reason why it makes sense to question our assumptions.

Some aspects of special relativity (SR) remain untested. They're assumptions, and if they aren't right, then the accelerating expansion of the universe is attributable to measurement error. To get the right cosmological measurements, we'll have to regard time dilation as skewing red shifts and compensate for it.

Please note that I am not asserting that SR's reciprocal time dilation is wrong, only that it's untested.
Urgelt
1.9 / 5 (7) Nov 10, 2015
The other reason to question our assumptions is that it's easier than postulating a whole new energetic field, for which we have no firm theories and no evidence for any theories. Nail down what we think we know first, then go from there.

It should not be *that* difficult to test reciprocal time dilation. If GPS satellite acceleration throws us off the scent, look at something not in orbit around the Earth.

Voyager has a clock. We have clocks. I don't know if Voyager's clock has enough precision to use it for this purpose, but I'd like to see physicists at least look into it.

Instead, they're spinning tremendously grand 'what-if' ideas, not even theories really, that would expand known physics vastly if true, but for which there simply isn't any evidence to suggest they're valid.

When you smell something burning, you don't spin a theory that the apocalypse has arrived. You look for something smaller first.
MaxwellsDemon
3 / 5 (11) Nov 11, 2015
I read Kipreos' paper a few months ago, and as someone who understands SR intimately, I have to say it was painful going: he makes a bunch of rookie errors. For example, time dilation is SR is indeed already asymmetrical – the accelerated POR is always time dilated wrt to the stationary reference frame. This is a consequence of spacetime geometry – accelerated reference frames move through less time than unaccelerated reference frames. This has been tested and proven ad nauseum. Kipreos has mistaken the observed rate of time between the two reference frames as physical – they're not; only the accelerated frame experiences less time, in actuality. He also doesn't understand the difference between time dilation in SR and GR – in GR both observers agree on the perceived rates of time, in SR they don't agree until they're back in the same reference frame. There are a few untested aspects of SR, but time dilation isn't one of them.
Urgelt
2.6 / 5 (9) Nov 11, 2015
Max, your self-proclaimed expertise is, well, bad.

GR's time dilation is directional, not reciprocal. Look it up.

In relativity, there is no such thing as a 'stationary reference frame.' Motion is relative. Everything moves.

The funny part is, Kipreos proposes an absolute reference frame, and it's possible to be stationary in reference to it. But Einsteinian relativity has no such feature.

You're using 'acceleration' in a very peculiar, and nonstandard, way when you say, 'accelerated reference frames move through less time than unaccelerated reference frames.' Actually, you can have time dilation with no acceleration at all - just compare two objects moving differently at fixed velocities.

Reciprocal time dilation has not been experimentally verified. *Time dilation* has. But demonstrating reciprocal time dilation requires examination of two differently moving clocks. The SR component in GPS is directional. There are no other experiments.
my2cts
2.5 / 5 (12) Nov 11, 2015
No kidding? Anyone with any kind of brain at all has said DM was BS to begin with. These strategies you mentioned should have been the ONLY solution from the get go. If you are more intelligent than a child it is OBVIOUS. Our understanding of G is simply wrong. Move on from there. Don't invent some other BS force and spend 30 years having people focus on the wrong thing.

Nice reaction with all the caps - no glasses needed - but this thread is not about DM.
my2cts
2.6 / 5 (13) Nov 11, 2015
... Our understanding of G is simply wrong. ...

GRT makes all the correct predictions and that there is no other theory that does. You make a fool of yourself by calling this problem "simple".
butch1192
2.1 / 5 (7) Nov 11, 2015
(Sorry for my English)

It is actually much easier

Gravity arises as a result of the "friction" of space. Of course, much more complicated in terms of the interaction of particles, than we are accustomed to observe.
Friction contributes to the emergence of magnetism (in-kind equivalent of "static electricity", only on a different level of particle interaction).

Why the friction? Friction is the result of pressure of the whole space + universe is in constant motion. Gravity accumulates in the space.

There is neither dark matter nor dark energy is an illusion.. the universe is not expanding - it pushes us out of the space.
The beauty part is that this version easily answers the question - how and why there was a big Bang.
jsdarkdestruction
3.7 / 5 (3) Nov 11, 2015
Well, with V Zarkova's theory of a dynamo underneath a dynamo in Sol, it seems to settle the matter that our system is uniquely different. As I have suggested, our sun was a red giant which I call the Beetle Sun, which was imploded by a massive magnetic grip to Sol and in doing so the off loaded 'dirty gases' created the rocky planets inside the former space of the Beetle Sun. The Oort shell is still very much in existence and whats more science notes that there are other 'hard edged' magnetic shells in our universe.
A science site is : Miles Mathis dot com

Why is our system uniquely different and how? Why don't other red giant stars implode because of "magnetic grip"? What do you mean by "magnetic grip"?
Ultron
1 / 5 (4) Nov 11, 2015
Yes, we need new theory of gravitation and it will be my new theory of gravitation :)

Just a hint for later confirmation in some years from now: Sagittarius A was a quasar in first phase of evolution of Milky way.
MaxwellsDemon
2.3 / 5 (9) Nov 11, 2015
Urgelt, please don't correct me on your mistakes. I said:
in GR both observers agree on the perceived rates of time

Which is A.) true and B.) not reciprocal. Time moves slower in gravitational fields: both observers (one deep inside the field and one essentially outside of the field) agree on this. This is different than SR time dilation where both observers see the other's clock moving slower.

My use of "accelerated" is common usage in SR discussions to distinguish between reference frames, for two reasons; 1.) "at rest" and "in motion" are meaningless within the context of SR, and 2.) this is a "twin paradox" discussion and it's always the accelerated twin that undergoes time dilation. That's why there's no such thing as "reciprocal time dilation." John Baez has compiled the experimental data that supports this and all of the other key features of SR here:
http://math.ucr.e...nts.html
MaxwellsDemon
3 / 5 (9) Nov 11, 2015
Actually, you can have time dilation with no acceleration at all - just compare two objects moving differently at fixed velocities.

You're making the same mistake that Kipreos makes: in SR the time dilation between different reference frames can be illusory – it's only when both observers share the same reference frame that we can see which POR had been accelerated relative to the other. This is illustrated by the twin paradox: the astronaut twin perceives time running slower on Earth, but this proves to be an illusion. When he returns to Earth and the reference frame of the homebody twin, homie is older – he didn't actually experience time dilation after all, only the accelerated astronaut twin did. If SR time dilation were "reciprocal," the clocks of both twins would agree when they shared the same reference frame again. Airborne tests and the GPS system have proven unequivocally that SR and GR model time dilation precisely.
Urgelt
1.6 / 5 (7) Nov 11, 2015
First point: okay.

Second point: yes, 'at rest' and 'in motion' are meaningless in the context of SR as explained by Einstein. But I don't think you can say 'this observer is going faster than the other observer.' They're moving relative to each other in SR, not relative to the universe, which has no absolute frame. Einstein explained it this way: acceleration produces asymmetrical time dilation in the twin paradox. You can't say one is moving faster than the other in any absolute sense, but you can say that one changed vectors more than the other.

So, what about two bodies moving relative to each other but not changing vectors? There should be no twin paradox under SR. Time dilation should be reciprocal. And it's this assumption in SR that cosmologists use to ignore time dilation relative to distant cosmological objects when evaluating red shifts. They believe it cancels out. Does it? What does the evidence say?
Urgelt
1.9 / 5 (7) Nov 11, 2015
The evidence doesn't say much. GPS is the only two-clock experiment. The SR component is demonstrably directional - arguably owing to satellite's vector-changing (acceleration). We have no experimental evidence that we should treat SR's time dilation as reciprocal in observations of cosmological light.

We also have no evidence that the universe lacks a universal frame. When you ask physicists about that, they shrug and say it's impossible to prove that it doesn't, so go away.

Kipreos is suggesting a way to nail it down. If it can be shown that SR's time dilation, absent acceleration, is directional, then there is a universal frame, a 'coordinate' system within which every object can be mapped, and the Absolute Lorentz Transformation describes how relativity works in that frame.

It's a wild, wooly, crazy, scary idea and is *probably* wrong. Probably.

But the way you dubunk it is with evidence, not reasoning by analogy.
MaxwellsDemon
2.1 / 5 (7) Nov 11, 2015
You're raising a lot of issues; 1000 characters just isn't sufficient. Let's stick to the big picture.

The "Absolute Lorentz Transformation" that Kipreos describes uses the center of Earth as a "preferred rest frame." This is obviously absurd. The earth revolves around the sun, which is revolving around the galactic center, etc., and the planet's center is also where the local gravitational time dilation is at a maximum value.

Sadly, Kipreos may actually have a point, but he doesn't know SR or GR well enough to state it properly. It's reasonable to ask "have we properly calculated cosmic-scale time dilation in the context of the Hubble expansion?" That's actually a valid question. Parsing the SR and GR components of time dilation within the cosmological redshift is tricky business...maybe we've modeled it wrong.

Instead he attacks SR on false grounds because he doesn't understand it clearly. So his paper is a wasted opportunity to ask the right question.
MaxwellsDemon
2.1 / 5 (7) Nov 11, 2015
But I don't think you can say 'this observer is going faster than the other observer.'

According to the four-velocity relation, all reference frames are moving at C. The differences arise because each reference frame has a different ratio of velocity and time components relative to another. It takes more information than the relative velocity between two bodies to know the components of each body's trajectory through spacetime; clock synchronization or properly defining a rest frame will suffice. There's no need to resort to an "absolute reference frame" to do either. And it turns out that the twin paradox works even without accelerations, if one employs observers moving at constant velocities in opposite directions. But defining relativistic simultaneity is essential in that case. Physically, the critical issue isn't the acceleration; it's the duration spent in the reference frame of higher velocity relative to a precisely defined event in spacetime.
Mimath224
3.7 / 5 (3) Nov 11, 2015
You're raising a lot of issues; 1000 characters just isn't sufficient. Let's stick to the big picture.

The "Absolute Lorentz Transformation" that Kipreos describes uses the center of Earth as a "preferred rest frame." This is obviously absurd. The earth revolves around the sun, which is revolving around the galactic center, etc., and the planet's center is also where the local gravitational time dilation is at a maximum value.

Sadly, Kipreos may actually...

Instead he attacks SR on false grounds because he doesn't understand it clearly. So his paper is a wasted opportunity to ask the right question.

I have been searching (net) for the paper you mention but unable to find. Perhaps you could direct me. (is it the paper 'We Don't Need to Chuck Our Best...') Thanks.
MaxwellsDemon
2.1 / 5 (7) Nov 11, 2015
I have been searching (net) for the paper you mention but unable to find. Perhaps you could direct me. (is it the paper 'We Don't Need to Chuck Our Best...') Thanks.

Here's the updated 2015 version of Kipreos' 2014 paper "Implications of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration"
www.ncbi.nlm.nih....s002.pdf
Mimath224
3.3 / 5 (3) Nov 12, 2015
MaxwellsDemon, Although a layman I do prefer SR & GR though I must admit that I've only read opposing authors that seem to falter obviously one way or another (imo). Many thanks, have a good day.
Urgelt
1.9 / 5 (7) Nov 12, 2015
Max, the claim that Kipreos establishes Earth as the center of the 'absolute frame' is not one he makes. It's a claim made by certain critics to dismiss him.

To the contrary, Kipreos posits that the Absolute Lorentz Transformation works for any observer anywhere in the universe.

I'm frankly doubtful. But really, we ought to want to test SR's reciprocity regardless of what Kipreos says. Leaving it as assumed is crazy, as the assumption is critical to our interpretation of cosmological light and the conclusions we are drawing from it.

It's worth noting that alternative theories of gravity are challenges to Einstein's GR every bit as far-fetched and boat-rocking as the Absolute Lorentz Transformation is to SR. The difference is with gravity, we have tons of observations validating it, including its time dilation directionality. SR's reciprocity is still untested.
Urgelt
1.9 / 5 (7) Nov 12, 2015
Max, you said that the twin paradox remains between unaccelerated bodies moving differently.

Not really. SR's reciprocity insists that there can be no paradox; they will age equally, since time dilation drops out of the equation, and SR says we compare each to the other, not to a third frame of reference. This assumes, of course, that there are no gravitational effects to consider.

Under SR, when we compare relative velocities of two observers, we cannot say one is moving faster than the other. They are moving *relative* to one another. Neither is faster or slower.

Under the Absolute Lorentz Transformation, each observer is regarded from a universal frame of coordinates, and it *is* possible for one to be moving faster than the other. This will result in directional time dilation, and you can get the twin paradox.
Mimath224
5 / 5 (2) Nov 12, 2015
Max, the claim that Kipreos establishes Earth as the center of the 'absolute frame' is not one he makes. It's a claim made by certain critics to dismiss him.

To the contrary, Kipreos posits that the Absolute Lorentz Transformation works for any observer anywhere in the universe..

This is the Kipreos paper quote;
'In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass.'
An equivalent to such a frame would be non rotating Earth center of mass would it not?
Urgelt
1.6 / 5 (7) Nov 12, 2015
Yeah, he's attempting to explain GPS directionality, which is dominated by Earth's gravity (GR). SR is a lesser driver of time dilation, but the SR component is *also* directional. Kipreos thinks gravity may provide a direction for SR, as it does for GR.

But he doesn't claim Earth as the center of an absolute frame for all observers throughout the universe. He's just proposing the possibility that Earth's gravity determines SR directionality for GPS satellites in orbit around it.

That in itself is a hell of a what-if.

My gut - which has never won a Nobel prize, it must be said - says he's wrong about that. But I don't think it matters how right or wrong Kipreos is. If we're going to throw around GR-defying hair-on-fire gravitational theories to explain Dark Energy, we'd be smart to also nail down SR's assumed reciprocality. 'Cause if it isn't reciprocal, then we've got to figure out how SR really works and factor that into interpretations of cosmological light.
Urgelt
1.7 / 5 (6) Nov 12, 2015
Let me put it another way.

We have observations that are not compatible with our understanding of physics. Something in our theory is wrong or incomplete.

A big part of our understanding is supplied by SR and GR.

This article is one of many floating around the internet suggesting that it's GR that is wrong or incomplete - though GR has been well-tested in nearly every conceivable way.

Meanwhile an important aspect of SR has gone untested. If it's wrong or incomplete, then our observations, interpreted through SR, need corrections.

Testing SR's time dilation receprocity may confirm Einstein. (Probably.) That's still a valuable contribution to science for experimentalists to make.

Ideally, we'd use two moving objects with clocks which are not accelerating through orbits.

New Horizons and Voyager have clocks, their acceleration is low and nonorbital, they have decent delta-V relative to one another... perhaps we could use them to test SR's reciprocity?
MaxwellsDemon
2.5 / 5 (8) Nov 12, 2015
Mimath224
Although a layman I do prefer SR & GR though I must admit that I've only read opposing authors that seem to falter obviously one way or another (imo). Many thanks, have a good day.

Glad to help. Everybody goes after relativity because finding a flaw in Einstein's work would be like winning the crackpot lottery. Ultimately it's a good thing, because challenges only strengthen a good model, but it's just so excessive. When I worked at USC's graduate physics dept. we got calls and mailed manifestos nearly every day from loons proclaiming "Einstein was wrong!! And my [whacky] theory [du jour] proves it!!" All of them, like Kipreos, had simply failed to understand the theory.
MaxwellsDemon
2.5 / 5 (8) Nov 12, 2015
Urgelt
we ought to want to test SR's reciprocity

Did you see the expansive list of tests in the Baez link I posted earlier? SR has been tested in every way possible, several times in most cases, with triumphant results. It's been months since I read this paper – in what way does Kipreos say that SR remains untested? What could New Horizons and Voyager tell us, that we haven't already checked in the lab?
Max, you said that the twin paradox remains between unaccelerated bodies moving differently.

Not really.

Yes, really:
the effect also arises if one imagines separate outward-going and inward-coming travellers, who pass each other and synchronize their clocks at the point corresponding to "turnaround" of a single traveller. In this version, acceleration plays no direct role;[12][13][14] "the issue is how long the world-lines are, not how bent"

https://en.wikipe...leration
MaxwellsDemon
2.5 / 5 (8) Nov 12, 2015
The apparent "reciprocity problem" you're raising is an illusion produced by only considering half of the twin paradox – two isolated reference points in nonuniform motion unable to tell who's "moving faster" than the other. But the answer requires an additional reference frame: one must know "relative to what?" One must define a reference frame to measure from, and any one will do. In each case, SR provides a precise and correct answer. You and Kipreos are insisting on an absolute value, and faulting SR for not providing one. But in SR time dilation is determined by the angle between two reference frames and the length of the trajectories through spacetime. Relative motion alone isn't enough information. It's as if the answer is a quantum superposition of all possibilities until you define the reference frame you're measuring the motion from.
MaxwellsDemon
2.5 / 5 (8) Nov 12, 2015
bschott
Time dilation is a human perceptual artifact, not a physical reality.

Let's say that we have a launch platform in deep space, with a rocket ready to go. To test SR, we'll synchronize two clocks, keeping one with us on the platform, and putting the other on the rocket before we launch it. The rocket fires away and eventually reaches relativistic speeds before returning to the platform. Then we compare the two clocks, and find that the rocket's clock has aged substantially less than the clock left behind. That's physical, not perceptual. And it's been proven again and again experimentally.
https://en.wikipe...periment
The effect disappears if you view everything simultaneously

There is no universal reference frame to establish simultaneity. Relativistic simultaneity is frame dependent, which is why clock synchronization plays such a key role in SR.
Urgelt
1.7 / 5 (7) Nov 12, 2015
Max, you defined the twin paradox this way: "two isolated reference points in nonuniform motion unable to tell who's "moving faster" than the other." That isn't right. The twin paradox involves two observers moving through time and space but experiencing it differently - when they meet up again, one twin is older, one is younger.

You wrote: "the answer requires an additional reference frame: one must know 'relative to what?'" But SR is a two-body solution, and imposes no other reference frames to get its answers.

You wrote, "You and Kipreos are insisting on an absolute value, and faulting SR for not providing one."

I wish you would carefully read my posts. I am *not* endorsing ALT. And in fact, if you read Kipreos, he isn't endorsing ALT either. He's proposing it for consideration, not insisting it's true. I'm not even going that far; I just want SR's reciprocity to be experimentally confirmed.
Urgelt
1 / 5 (5) Nov 12, 2015
Max, you wrote, "SR has been tested in every way possible, several times in most cases, with triumphant results." And, "...in what way does Kipreos say that SR remains untested?"

To the first point: no, SR has not been tested in every possible way. The only available test of SR's predicted reciprocity, the aspect of SR that lets cosmologists drop out time dilation from their interpretation of cosmological light, is GPS. GPS does not demonstrate SR's reciprocity. The SR component appears to be directional; e.g. the satellite is dilated, clocks on Earth are not. There are lots of experiments which probe and validate SR in other ways, but reciprocity, no.
Urgelt
2.1 / 5 (7) Nov 12, 2015
Going back to the twin paradox: SR doesn't require a third frame. It's acceleration that determines which twin is dilated more - change in velocity. Relative to the observer on Earth (who is *not* regarded as stationary), he changes velocity more, and so is designated the 'faster' of the two observers.

I do find this approach to frames unsatisfying; always have. But the best argument against any two-body solution is the universe isn't a two-body problem. It's an n-body problem. And where SR tells us we can't solve for all of those bodies at once, but must take them two at a time, the universe has no such restrictions. It solves the n-body problem and there really isn't any confusion about where in space-time each object is.

Whether that solution is approximated by ALT or not, I don't know. I'm very doubtful. But that doesn't mean I have confidence in SR as correct. An advance over what came before, certainly, but it *can't* be the last word on space, time and motion.
Urgelt
1.7 / 5 (6) Nov 12, 2015
SR's twin paradox plays out this way, in the absence of acceleration: the twins remain the same age, though they are moving differently. This is specifically because there is no external reference frame permitted. This is the heart of what SR's time dilation reciprocity means. And this is exactly how astronomers are regarding distant cosmological objects moving differently from us: they presume any time dilation effects cancel out at both ends, and so are not present in redshifts/blueshifts. We proceed to develop estimates of vectors and distances from that starting assumption.

Kipreos may well be wrong in his solution to SR. (Probably.) But a very interesting consequence of ALT is that if you regard time dilation as directional, not reciprocal, and adjust for it in a sampling of Type 1a supernovae, the accelerating expansion goes away. You get EInstein's cosmological constant instead. That's an amazing coincidence, if nothing else.
Urgelt
1.7 / 5 (6) Nov 12, 2015
So: we know something is wrong or missing from fundamental physics theory. There's a mistake somewhere. Some physicists are looking eagerly at new theories of gravity to overturn GR; one such theory gets an airing in this article.

But the hardest thing to demonstrate in any of Einstein's work is the absence of a universal frame. Yet this aspect of SR is critical to our interpretation of cosmological light. If it's wrong, dark energy, an unexplained hole in theory, is solved.

The argument for attacking GR rests on our inability to unify gravity with the other fundamental forces. Physicists believe it's an incomplete formulation. But that expectation isn't resolved. If there's a flaw in GR, we don't know what it is. The attacks themselves are, well, crazy. Like the one which requires a 'dark electromagnetic spectrum' and 'dark photons,' though it doesn't describe any of these things with math or make predictions. Occam's razor prefers to avoid such enormous leaps.
MaxwellsDemon
2.8 / 5 (9) Nov 12, 2015
I replied before you posted more comments...I'll read the rest before continuing.
Urgelt
1 / 5 (5) Nov 12, 2015
I suppose there's one more reason for positing theories to overturn GR: if we attack GR, we don't have to revise our interpretations of cosmological light. We can keep ignoring SR's time dilation effects in redshift/blueshift. There's no do-over required.

There's also no egg on the faces of physicists who leaped on board the 'accelerating expansion of the universe' observation. Avoiding embarrassment is a very human motive.

Maybe there should *not* be egg on those faces. Maybe SR's time dilation *is* reciprocal. But GPS - a satellite undergoing constant acceleration relative to Earth - doesn't help us to show reciprocity. And we don't have any other experiments we can point to which do show reciprocity.

Showing SR's reciprocity experimentally will point away from an absolute frame and lend support to Einstein's interpretation of relativity. Falsifying reciprocity will point to the need for a cosmological do-over. Those are large stakes!
Urgelt
2.1 / 5 (7) Nov 12, 2015
Max wrote, "I replied before you posted more comments...I'll read the rest before continuing."

You are impeccably polite, sir. I tip my hat to you.

I'm kinda-sorta done for the moment, so post away.
my2cts
2.2 / 5 (9) Nov 12, 2015
"Do we need a new theory of gravity?"
GRT explains a few things but is very complex and does not mix with the rest of physics.
Of course this is very unsatisfactory.
Yes we need a new theory, today, but not just any new theory: it should be _better_ than GRT.
I frankly don't give a damn, my dear, if it is thought up by a woman. By all means.
my2cts
2.3 / 5 (9) Nov 12, 2015

the edge of the universe.

Bschott, don't go there, you will fall off the cliff!
http://glamboy69....arth.jpg
Urgelt
2.4 / 5 (8) Nov 12, 2015
bschott wrote, "1 second is 1 second, it is a fixed amount of time, but measured by a mechanical movement. Velocity effects complex systems, not actual time."

For the record, I do not endorse this viewpoint. The elasticity of time (time dilation) is unquestionable in modern physics. So is the invariant speed of light in a vacuum, which time dilation preserves for all observers regardless of motion.

my2cts wrote, "GRT explains a few things but is very complex and does not mix with the rest of physics. Of course this is very unsatisfactory."

Agreed. I'm skeptical, though, of a 'theory' which requires an undetected and undetectable electromagnetic spectrum and 'dark photons,' but doesn't bother with any math at all and makes no predictions.

The idea of a universal frame, though contradicting SR and therefore alarming, is at least one that can be tested by probing SR reciprocity. I much prefer testable theories to those that are 100% assumptions.
baudrunner
3.7 / 5 (3) Nov 12, 2015
Understanding gravity requires first understanding what light is and how light behaves. The "constant" c is true in describing the rate of interaction of particles in a photonic wave propagating medium. In 1850, Leon Foucault used the Fizeau–Foucault apparatus to demonstrate that "light travels slower" through water than through air. In fact, the rate of particle interaction is the same, that for a given distance there are just more water molecules than atmospheric particles. The logical conclusion then, that light travels slower through air than through the vacuum of space for the same reason, is a valid one. In fact, light doesn't travel faster, it is that particle interactions occur over a much greater distance for the same time frame that leads to that assumption. We should begin our understanding of gravity from that underlying principle, because we are basing our theories of DM and DE on physical observations of photonic wavelengths.
Urgelt
1.7 / 5 (6) Nov 12, 2015
bschott, the universe has existed for well over 14 billion years. Humans have been in it for almost none of that time.

Face it. The universe doesn't need humans to exist or for time to pass. Pretending otherwise is to echo Carson's idiotic stance on belief, which can be summarized thusly: We all choose what to believe, so what's wrong with choosing anything at all? All beliefs are as legitimate as any other beliefs, except when God tips the scales and says this one's better than that one. So let's all listen for God to whisper in our ears.

Delusional.
Bloodyorphan
3.7 / 5 (6) Nov 12, 2015
So how does GRT explain Gravitational Acceleration ?

Anyone ??
MaxwellsDemon
2.1 / 5 (7) Nov 12, 2015
Urgelt
Max, you defined the twin paradox this way: "two isolated reference points in nonuniform motion unable to tell who's "moving faster" than the other."

No, I said that's *only half* the scenario, not the full scenario - which is precisely the problem that you and Kipreos are having with the GPS/time dilation scenario: two bodies in uniform motion is insufficient information. The twin paradox requires 1.) Twin A at v1, 2.) Twin B at v2, and 3.) a Rest Frame to determine v1 and v2 relative to it. GPS satellites and ground stations don't both constitute inertial (and therefore equivalent) reference frames, because the satellites were forced into a new reference frame, so the time dilation is not symmetrical between them.

The symmetry of SR time dilation between *inertial reference frames* has been confirmed in the lab via measurements of the relativistic Doppler shift, which contains gamma (the time dilation factor).
MaxwellsDemon
2.1 / 5 (7) Nov 12, 2015
Urgelt
And this is exactly how astronomers are regarding distant cosmological objects moving differently from us: they presume any time dilation effects cancel out at both ends

That's because we presume that the expansion we observe is due to the Hubble expansion of spacetime. If, however, there's a force component involved in the observed velocities, then some of the time dilation we see would be asymmetrical. Perhaps there's a force component to inflation that we need to account for – unfortunately we have little understanding of the inflation mechanism so it's impossible to say at this point.

But the hardest thing to demonstrate in any of Einstein's work is the absence of a universal frame.

The cosmic microwave background is a universal frame. The Local Group is moving at about 627km/s relative to the CMB.
https://en.wikipe...isotropy
MaxwellsDemon
2.1 / 5 (7) Nov 12, 2015
bschott
the closer you get to c in one direction, the more difficult it becomes for an EM wave to oscillate in the same direction you are traveling

A body in uniform motion doesn't sense its own velocity; relativistic momentum only applies to observations –between- reference frames. If you were traveling at .9C right now you wouldn't feel a thing, and the laws of physics wouldn't be any different for you than they are at rest. That's a central pillar of relativity.
MaxwellsDemon
2.1 / 5 (7) Nov 12, 2015
Bloodyorphan
So how does GRT explain Gravitational Acceleration ?

In GR, gravitational acceleration is synonymous with a gradient in spacetime curvature: the steeper the gradient, the more intense the acceleration. The current problem in theoretical physics is how to reconcile this concept with the Standard Model of quantum mechanics, which describes all of the other forces in nature in terms of force-mediating particles called bosons. Most physicists expect the "curved spacetime" model to reduce to a theory of gravitons - a force-carrying boson particle for gravity, but our best detectors would be far too insensitive to detect them, if they exist at all.
Bloodyorphan
3.4 / 5 (5) Nov 12, 2015
Exactly MaxwellsDemon,

GRT does not define Gravity, it simply describes ones of it's effects.

To say GRT is a theory of Gravity is taking it one step to far IMO.

GRT describes space as a curved space based on mass, yet when an object falls it has a flat trajectory, decrying the curved space, until we discover a sub space medium curved space remains a theory, one that mathematically describes the phenomenon very well but that is where it ends.

The same is true for photonic lensing.
Urgelt
1 / 5 (5) Nov 12, 2015
Max, I feel we are not quite on the same page, but that's okay. There are points of consanguinity that lead to the same conclusion.

You see SR's reciprocity as assumed, as I do. You acknowledge that there *may* be asymmetrical time dilation (what I've been calling directional) - but aren't sure. Me, too.

I've seen the CMB described as a universal frame, but we never seem to take that insight anywhere when considering SR, which forbids any sort of universal frame.

I think there's enough to merit the experimental investigation of SR's presumed reciprocity. I'll be happy with any outcome, I just want there to *be* an outcome. We can pick up the pieces and go from there, if we know reciprocity is real or not.

If not, then we are doing cosmological measurements incorrectly, and that's a big huge deal.
Bloodyorphan
3.4 / 5 (5) Nov 13, 2015
@Urgelt

If the red shift increases then the velocity has changed, time dilation doesn't have any bearing on that.

If time dilation has an affect on the changed red shift, then again it's because of a velocity difference.

You arguments are, as far as I can see, self defeating.
my2cts
2 / 5 (8) Nov 13, 2015
Exactly MaxwellsDemon,

GRT does not define Gravity, it simply describes ones of it's effects.

That effect is gravity.

To say GRT is a theory of Gravity is taking it one step to far IMO.

It is a theory that predicts gravity with as yet unchallenged accuracy.
So, a theory of gravity.

GRT describes space as a curved space based on mass, yet when an object falls it has a flat trajectory, decrying the curved space,

Please check if you actually understand GRT.
until we discover a sub space medium curved space remains a theory, one that mathematically describes the phenomenon very well but that is where it ends.

How else do you require it to be described?
The same is true for photonic lensing.

Photonic lensing is part of GRT, so why name it explicitly?
Urgelt
1.2 / 5 (6) Nov 13, 2015
BO, in the observation of a particular cosmological object, often billions of light years away, we don't see increases or decreases in spectrum shifting in real time. On human time scales the spectrum lines almost always appear to us to be fixed. But the lines are shifted, because those objects are moving towards or away from us.

Cosmologists interpret SR to say that whatever spectrum shifting they see isn't affected by time dilation, because it's presumed to be reciprocal; e.g. both the distant object and Earth observers are equally affected. Buried in that assumption is another: there is no universal frame against which to judge an object's velocity in time and space.

The problem is simple: SR's reciprocity and SR's prohibition against a universal frame haven't been experimentally validated.

The argument I am making - the *only* argument I am making - is that we really ought to nail down SR's assumptions experimentally.

How is that self-defeating?
Bloodyorphan
3.3 / 5 (7) Nov 13, 2015
@my2cts
GRT describes an affect, it does not explain what Gravity is or how it works. Hence people talking about gravitons etc, which BTW would actually disprove GRT.

If you think I have it wrong, then please enlighten me as to what curved space in GRT actually means.

@Urgelt
The observation is... Space is expanding at and increasing rate.
Please explain what they mean my increasing rate.
(Just so you know I already know the answer to the above question as outlined in my previous post)
Urgelt
1.7 / 5 (6) Nov 13, 2015
BO, go ahead and explain what you think you know. It'll amuse the regulars.
Bloodyorphan
3.3 / 5 (7) Nov 13, 2015
@Urgelt

Since you are one of the regulars, and want everyone to know how much you know, use your 1000 words to explain why astrophysicist's think the universe is expanding at an increasing rate.

I await your professor level of knowledge with humble eagerness Urgelt 8-)
Benni
3.2 / 5 (9) Nov 13, 2015
.... the more difficult it becomes for an EM wave to oscillate in the same direction you are travelling...hence "slowing" of the oscillation occurs. Thus two moving objects experience a time dilation between them, and it is amplified at relativistic speeds. But a "stationary" clock remains unaffected.

This is how light can be both a particle and wave. The "leading edge" of a photon is "solid" at c.


This effect occurs because as you accelerate closer to c, more time mu0st pass before you see the next peak/valley of the frequency of a light wave that passing you, this as opposed to when you were accelerating at a slower speed & lightwaves were passing you at a relatively faster rate of speed.

When you reach c everything in the universe looks like a point because lightwaves can never pass you & therefore you can never see the peaks & valleys of the oscillations (frequency) of the lightwave.

my2cts
2 / 5 (8) Nov 13, 2015
@my2cts
GRT describes an affect, it does not explain what Gravity is or how it works.

GRT describes all the effects of gravity, although you can argue about DM or DE.
Hence people talking about gravitons etc, which BTW would actually disprove GRT.

What is the rationale of this statement ?
Urgelt
1.7 / 5 (6) Nov 13, 2015
BO, if you want knowledge, look it up. I am not here to spoon-feed it to you. I'm here to talk to the several people who actually care about science and are not lunatics.

Keep trolling and I'll add you to my ignore list without a backward glance.
my2cts
2 / 5 (8) Nov 13, 2015
What BO means, and I have to guess here be cause he remains unclear, is that GRT does not tell us what "space" is made of, much like EM theory of light does not tell us what oscillates. The theory of sound does explain what sound is. That fact does not mean that these are not theories of gravity and light.
Bloodyorphan
3.4 / 5 (7) Nov 13, 2015
@My2cts

Why does curved space cause acceleration ?

And how does curved space explain this acceleration ?
Bloodyorphan
3.3 / 5 (7) Nov 13, 2015
@Urgelt

The observed increase in Red Shift is why astrophysicists think the Universal expansion rate is increasing.

PLEASE Explain why time dilation is causing the increase in red shift ?
Urgelt
2 / 5 (7) Nov 13, 2015
BO,I don't know if it is. Nobody here knows.

SR says it can't distort spectrum-shifting, because SR's time dilation is reciprocal between two bodies in motion relative to each other. SR's formulation is the consensus view in physics. But it hasn't been nailed down experimentally.

I don't assert that SR is wrong. But it makes key assumptions that haven't been tested.

If it turns out that SR's time dilation is directional, then the spectrum-shifting we see in cosmological objects is affected by it. To obtain true velocities and distances, we'll have to back out the distortion. The difference isn't large, but it's exactly enough to return the universe to expanding at the rate of Einstein's cosmological constant, according to Kipreos' back-of-the-envelope calculations using Type 1a supernovae. The acceleration goes away.

But of course that was a quick and dirty analysis. If SR's time dilation should be directional, then a whole lot more work will be needed.
Bloodyorphan
3.3 / 5 (7) Nov 13, 2015
If what you are saying is true, the time dilation is variable, yet the direction is the same.

Why would the time dilation be variable ?

Your statement ...
The difference isn't large, but it's exactly enough to return the universe to expanding at the rate of Einstein's cosmological constant


Does not make sense.
Bloodyorphan
3.3 / 5 (7) Nov 13, 2015
After having a quick read of Kipreos' theory here ...
http://motherboar...k-energy

I have to say his assumption about time dilation is completely wrong, metabolic/atoomic time is not universal time, and his theory actually has no real relationship with SR at all.

It is in fact based on his misinterpretation of what time dilation actually is.
Urgelt
2.1 / 5 (7) Nov 14, 2015
"...metabolic/atomic time is not universal time..."

You're babbling.

"...and his theory has no real relationship with SR at all."

For a fellow with an obviously high regard for his comprehension of physics, your reading comprehension leaves a lot to be desired.

Whether spectra from distant cosmological objects should be adjusted for time dilation, or not, is exactly and precisely an SR question.

Read it again, and this time, pay attention.

I'm not asking you to agree with Kipreos' suggestion. He doesn't even ask that of the reader. He's just proposing a place to look for an explanation of dark energy. Something in theory, somewhere, is off. It might be in SR. SR's reciprocal time dilation, used by cosmologists to justify ignoring time dilation in spectra, ought to be demonstrated experimentally before we trust it completely.
Bloodyorphan
3.3 / 5 (7) Nov 14, 2015
You are the one babbling Urgelt, you and Kipreos think you understand what time dilation means but it is very clear to me that you have no idea what so ever.

Neither you nor Kipreos have explained why time dilation would cause an increase in red shift. I'd really like to see his so called "equations".

The only reason we know for time dilation to change is for the velocity to change.
The only reason for the red shift to change is for the apparent velocity to change, be it the relative objects speed or the space expanding between the observer and the object.

For Kipreos and yourself to think that Universal time has changed and therefore affect a photon traveling through space as it is traveling is beyond the realms of reasonable, and highlights to me you have no idea what time dilation means.

Once a photon has left its source it is traveling at C, it's time dilation will be constant at that speed, and as far as we know can only decrease.
Urgelt
1.7 / 5 (6) Nov 14, 2015
You are babbling word salads promiscuously. That works for propagandists at Fox News. It doesn't work for physics.

A photon has no intrinsic time dilation, let alone a constant one.

Time dilation is between objects. Light is only an information/energy carrier between objects. There *will* be time dilation between objects moving differently. The question is, does it or does it not contribute to spectral line-shifting? Cosmologists, citing SR, say 'no.' Time dilation cancels because it's reciprocal, both objects experience the same time dilation. Kipreos is saying that their answer hasn't been validated by experimental confirmation. He is also saying that *if* there is a universal frame, which SR denies, we might make sense of time dilation that does contribute to spectra shifting, and the need for a dark energy explanation goes away.

The Absolute Lorentz Transformation provides the math, if you're interested.
viko_mx
3.7 / 5 (6) Nov 14, 2015
"In the late 1990s physicists discovered, to their consternation, that the expansion of the universe is not slowing but accelerating. "

On geometric objects like space with which mathematical apparatus of GR work, can be carried out arbitrary mathematical operations without restrictions. It can expand and contract without limits because it is not a real physical object.
Not so it goes with real physical objects and environment such as cosmic vacuum that fill the geometric space.

What physical characteristics and properties gives GR to space which operates its mathematical apparatus? Where?
viko_mx
3.3 / 5 (7) Nov 14, 2015
The problem with gravity is solved elegantly with the programmed properties of the structure of vacuum of space locally. Global theory of gravity is impassible for that reason.
Bloodyorphan
3.7 / 5 (6) Nov 14, 2015
Kipreos postulates that in the EARLY Universe, and if time variance is directional that the light would be blue shifted because of time contraction. And justifies this with experiments of east / west time dilation observations.

If the early universe expansion rate is the same as it is today, then there was no time contraction, nor is there any time dilation now, as the rate of expansion is constant and all the bodies being observed are moving at the same relativistic speeds away from each other (I.E. any Blueshift or Redshift we observe would be constant)

Only if the expansion rate is increasing does time dilation variance become plausible, therefore defeating his own argument.

my2cts
2.1 / 5 (7) Nov 14, 2015
@My2cts

Why does curved space cause acceleration ?

And how does curved space explain this acceleration ?

Again, you do not understand GRT.
Bloodyorphan
3.7 / 5 (6) Nov 14, 2015
I understand it budy, come on use your 1000 chars and explain why objects accelerate in a Gravity Field
Mimath224
3.7 / 5 (3) Nov 14, 2015
This was a statement apparent made by Prof. Kipreos;
University of Georgia Press Release;
Special relativity is supposed to be reciprocal, where both parties will experience the same time dilation, but all the examples that we have right now can be interpreted as directional time dilation," Kipreos said. "If you look at the GPS satellites, the satellite time is slowing down, but according to the GPS satellites, our time is not slowing down — which would occur if it were reciprocal. Instead, our time is going faster relative to the satellites, and we know that because of constant communication with the satellites."
Please correct me if I'm wrong but GPS is just affected by SR but also GR frequency shift and the GR effects are something like 6x greater than SR TD. These figures are easily done using 1st approx of Binomial. This is not to mention other errors that are inherent in averaging calculations and more. Sounds like Prof. K is too simplistic.
Urgelt
2.1 / 5 (7) Nov 14, 2015
Just block him, my2cnts. The concept in physics he can grasp hasn't been invented. He doesn't even qualify for the title 'crank.'
my2cts
1.7 / 5 (6) Nov 14, 2015
I understand it budy, come on use your 1000 chars and explain why objects accelerate in a Gravity Field

Why do you pose newbe questions?
If you understand GRT make a statement on GRT that is based on your understanding.
And make it interesting this time.
Urgelt
2 / 5 (7) Nov 14, 2015
Mimath224, you are correct. GPS time dilation is dominated by GR. But there is an SR component. Kipreos in his paper doesn't do a great job of breaking that down, but he's only talking about the SR component.

Which is directional. Earth clocks do not need to be adjusted. Only GPS on-board clocks require adjustment - for both GR and SR influences on time dilation.

GPS satellites are in constant acceleration. SR allows directional time dilation for accelerated objects - that's how you get the 'twin paradox.'

GPS is the only test of SR's reciprocal time dilation that Kipreos could identify. I don't know of any other tests of it, either. There's lots of proof that there is time dilation in the first place, but showing that you can reasonably drop time dilation from interpretations of cosmological light hasn't been experimentally demonstrated to be correct - far as I can tell.

If it is not correct to ignore it, then it's a big deal.
Urgelt
1.7 / 5 (6) Nov 14, 2015
Clarifying: when I wrote "GPS is the only test of SR's reciprocal time dilation..." I didn't mean to imply that the test is satisfying, in the sense that we can shout 'eureka! SR reciprocity is disproved!"

To the contrary, the test doesn't falsify SR at all. And that is the problem.

Distant cosmological objects are *not* in orbit around the Earth. They *are* time-dilated. What Kipreos is hunting for is some evidence that cosmologists are correct, or not correct, to ignore time dilation when interpreting spectra lines.

GPS doesn't show they are correct. That's what Kipreos is trying to say. There is no SR reciprocity there.

I think what we need is an unequivocal test of SR reciprocity. Maybe physicists can figure out how to do that with an orbital body, but I'd prefer a test that minimizes extraneous influences on the results.

That's why I hoped out loud for a test using Voyager and New Horizons spacecraft. Not in orbit, moving differently, clocks on board.
Urgelt
2 / 5 (7) Nov 14, 2015
Mimath224, I will confess that the reason this interests me is the framing question. If there is one thing that sits in my head like too much turkey on Thanksgiving sits in my belly, it's the notion that there can be no universal frame. Practically all physicists say Einstein was right about that.

I just don't like that interpretation. But it's not a matter of belief with me; it's more like an irritating itch that won't go away.

The Absolute Lorentz Transformation (ALT) scratches that itch by reinstating a universal frame for relativistic effects. It also gets rid of dark energy, which annoys *everyone* in physics. Who likes a great huge energetic effect with no explanation whatsoever? No-one. That's an itch *everyone* wants to scratch.

But liking a theory isn't enough to invest belief in it. That's why I'd like to see SR's reciprocity tested. If it passes, I'll just have to live in Einstein's crazy universe.
Benni
3.7 / 5 (9) Nov 14, 2015
The Absolute Lorentz Transformation provides the math, if you're interested.


......but only the "math". It doesn't explain the physical phenomena of why time dilation occurs in SR. Until you understand why lightwaves come closer to being a "point" the closer you get to c, then time dilation will never be comprehensible to the science aficionado.

At c, time dilation is 100% because there no longer remains a measurable distance between the peaks & valleys of a photon's wavelength. You must be moving at a speed less than c to discern time dilation because it is only through observing the frequency of a photon that time dilation can be measured.

MaxwellsDemon
2.1 / 5 (7) Nov 14, 2015
Urgelt
You acknowledge that there *may* be asymmetrical time dilation (what I've been calling directional) - but aren't sure.

Actually I have no doubt about that at all. The Hafele-Keating experiment and the GPS system convince me that the SR solution to the twin paradox is airtight: time dilation is symmetrical between inertial frames of reference, and asymmetrical between non-inertial frames of reference (such as the twin paradox, where only one twin changes reference frames). This is explained quite clearly on this page:
http://newt.phys....adox.htm

I've seen the CMB described as a universal frame, but we never seem to take that insight anywhere when considering SR, which forbids any sort of universal frame.

Well, it really only forbids a "preferred" universal rest frame. Since the laws of physics aren't biased with regard to the CMB frame, it doesn't contradict the mathematics of SR.
MaxwellsDemon
2.1 / 5 (7) Nov 14, 2015
Urgelt
I think there's enough to merit the experimental investigation of SR's presumed reciprocity.
Tests of the relativistic Doppler shift strike me as proof of time dilation symmetry between inertial reference frames. Since we use photon signals to measure velocity, the relativistic Doppler shift is the most direct way to measure time dilation without actually accelerating a physical clock to relativistic speeds and then returning it to the rest frame.

If not, then we are doing cosmological measurements incorrectly, and that's a big huge deal.

Clearly there's *something* rotten in the state of Denmark, and whatever it is, it's certainly a big deal. I lose a lot of sleep over dark energy and dark matter. Partly because resolving either or both will signal a revolution in physical understanding, partly because they smell like the head and tail of one bird, and partly because they look to me like the keys to metric engineering and manned interstellar spaceflight.
MaxwellsDemon
2.1 / 5 (7) Nov 14, 2015
bschott
What would my relativistic mass be at .9c if my resting weight is 190 lbs?

Your question is based on a false assumption: you're assuming that you can perceive your own relativistic mass within your own reference frame. It doesn't work that way. It's like time dilation: no matter how fast you move, you see *your own clock* ticking at the same rate. It's when you observe *other* frames of reference that you observe differences. No matter what your velocity, your inertial mass within your own frame of reference remains constant. But if someone in *your original rest frame of reference* tries to accelerate you faster than .9C, then your mass would appear to be ~2.29 times greater than it was at rest *from their frame of reference.*
my2cts
1.7 / 5 (6) Nov 14, 2015
There is no point in entertaining a separate notion of "relativistic mass" as this is the same as energy but divided by c^2.

Mass is a Newtonian concept which appears in two places, in Newtons first law F=ma and as the source of gravitation. In SR F=ma no longer holds, but m takes the form of the rest energy divided by c^2 In GRT energy takes over as the source of gravity. Thus, in post-Newtonian physics mass just means rest energy up to a constant factor.
my2cts
1.7 / 5 (6) Nov 14, 2015
P.S. In SR p=mv becomes P=Ev (divide by c^2) from which it can be seen that mass is replaced by E/c^2 in inertia and in gravity.
MaxwellsDemon
1.7 / 5 (6) Nov 14, 2015
my2cts
Evident from these two comments;
in post-Newtonian physics mass just means rest energy

and
In SR p=mv becomes P=Ev (divide by c^2) from which it can be seen that mass is replaced by E/c^2 in inertia and in gravity.

… "mass" is used to mean both "rest mass" and "rest mass + KE/c^2" depending on the context. I don't like the term "relativistic mass" either, because it leads to the kind of confusion that we see in bschotts' comment, but at least it explicitly invokes the total energy. If people would just specify "rest mass" when they mean "rest mass," the pervasive use of "relativistic mass" could finally be eradicated because "mass" would always be understood to mean "total energy / c^2" which would prime students to readily understand the key role of energy in SR and GR.
Urgelt
1.2 / 5 (6) Nov 14, 2015
Max, I'm glad you agree that SR's cosmological reciprocity merits investigation.

It's not clear to me how staring at cosmological spectra lines is going to get the job done, because that only gives us half of the data required to evaluate reciprocity. We'll be seeing effects only from one perspective, not both, which makes it tough to establish and quantify a direction for time dilation. Impossible, maybe.

But just because I can't see how to do it doesn't mean it can't be done, I suppose.
Benni
3.2 / 5 (11) Nov 14, 2015
I don't like the term "relativistic mass" either, because it leads to the kind of confusion that we see in bschotts' comment
Yes, because of your following statement:
but at least it explicitly invokes the total energy


If people would just specify "rest mass" when they mean "rest mass,"
Because "rest mass" exists nowhere in the Universe, therefore:
the pervasive use of "relativistic mass"
....but you want the accurately definitive term Relativistic Mass "expunged from use in favor of something that can't possibly exist, ever:
could finally be eradicated because "mass" would always be understood to mean "total energy / c^2"


which would prime students to readily understand the key role of energy in SR and GR.
,,,,which is exactly what the term Relativistic Mass does because it imputes the changing energy parameters of systems as they gain/lose momentum.

MaxwellsDemon
2.1 / 5 (7) Nov 14, 2015
Urgelt
Max, I'm glad you agree that SR's cosmological reciprocity merits investigation.

Actually, that was a typo. I forgot to place quote code around your words (oops) - it was supposed to read:

Urgelt
I think there's enough to merit the experimental investigation of SR's presumed reciprocity.

"Tests of the relativistic Doppler shift strike me as proof of time dilation symmetry between inertial reference frames. Since we use photon signals to measure velocity, the relativistic Doppler shift is the most direct way to measure time dilation..."

Sorry about that =) So why do you remain unconvinced by measures of the relativistic Doppler shift? Also, I wish you'd read the link I provided - it should clear up your questions about symmetrical and asymmetrical time dilation quite nicely:
http://newt.phys....adox.htm
MaxwellsDemon
2.5 / 5 (8) Nov 14, 2015
Benni
Because "rest mass" exists nowhere in the Universe

Coulda fooled me. I guess "gravity" is just a big con too, huh? 0.o
Urgelt
1.7 / 5 (6) Nov 15, 2015
Max, I'm stumbling over the same evidence - slight though it is - as Kipreos. In the only two-clock relativistic evidence we have, the SR component for time dilation affects only the satellite's clock, not the receiver. This is troubling.

GR predicts exactly that for gravity-induced time dilation, which is directional. So the GR component for GPS makes perfect sense. But why aren't Earth clocks slowed equally in comparison to GPS satellites?

On Earth, GPS receivers are not moving uniformly relative to the satellites. They're on a rotating body, and the GPS satellites are in orbit. So you get a curious mixture of comparative velocities. It's *not* a two-body problem.

None of those receiver clocks require fiddling to make GPS accurate. Only the GPS clocks have to be adjusted to yield accuracy, both for GR and SR time dilation (in different directions).

You can observe Doppler shift and know there is time dilation. But that doesn't tell you if it's reciprocal.
Urgelt
1.6 / 5 (7) Nov 15, 2015
Continuing: So long as reciprocity hasn't been experimentally validated, every reference you can point to is theory.

SR is a great theory. It's stood for a century and enjoys the consensus of physicists. It's elegant, truly.

But we know, for an absolute fact, that there is something wrong with our physics. The unexplained and apparent accelerating expansion of the universe tells us that either we have erroneous assumptions which haven't been validated experimentally, or there are physics we can't begin to explain.

This article attacks Einstein's theory of gravity and makes all kinds of astonishing deductive leaps - a dark electromagnetic spectrum among them. Evidence: none.

Kipreos attacks SR. Evidence: slight.

Links to theory will 'disprove' both attacks. Neither is allowed in consensus physics.

But there's an error somewhere. I think we need to look everywhere, including SR.
Urgelt
1.7 / 5 (6) Nov 15, 2015
Finally: what would it mean if SR's time dilation is directional in observations of cosmological light?

One thing it would mean is this: the Doppler shift we observe is slightly exaggerated in our frame of reference, because we are experiencing time dilation differently. Compensating for that exaggeration would reduce spectral redshifting by a small amount - which happens to be precisely the amount required to make the accelerating expansion of the universe go away. Kipreos' quick and dirty calculations for a sampling of Type 1a supernovae show that if this adjustment is made using ALT for assumptions instead of standard SR, you get Einstein's cosmological constant.

Could be a coincidence. Or Kipreos may have miscalculated. But Kipreos didn't invent the fact that GPS receivers on Earth require no clock adjustments to yield accurate positions.

I hope you will agree that SR's reciprosity merits further experimental investigation.
Urgelt
1.7 / 5 (6) Nov 15, 2015
Just a quick clarification.

Ground GPS receivers don't require a clock adjustment for GR to be accurate.

A GR adjustment to GPS satellite clocks *is* required. (GR speeds up GPS satellites' clocks.)

The other component of time dilation in GPS satellites is SR. It's a weaker effect, but it's there, and adjusting GPS clocks for it is necessary to yield accurate positions. SR slows down the satellite clocks.

But Earth-based receivers' clocks *must not* be adjusted for the SR component. If you adjust clocks for SR's time dilation in receivers, you get bad positions.

You can explain it away by observing that SR permits directional time dilation for accelerating bodies relative to unaccelerating bodies.

But that's problematical. The Earth receivers are accelerating, too, in a variety of velocities relative to the satellites, though accelerating more slowly (the Earth's rotation)..

We can see no trace of SR's reciprosity in GPS data. That's rather maddening.
MaxwellsDemon
2.5 / 5 (8) Nov 15, 2015
Urgelt
You can explain it away by observing that SR permits directional time dilation for accelerating bodies relative to unaccelerating bodies.

I wish you'd read the link; this really isn't that complicated.

You have two clocks on the Earth, synced. They're both in the same reference frame so they tick at the same rate. Then you accelerate one of the clocks to 14,000 km/hr - that's a new reference frame. Time is slower in that reference frame because you've added 14,000 km/hr to that POR. Clock 1 is still in the first frame, Clock 2 started in the first frame then moved to a second frame - so the time dilation reflects this asymmetry: Clock 2 runs slower than Clock 1.

This is different than a bullet passing you in space, where both frames remain unchanged during your observations. In this case, both frames observe the same time dilation in the other. The time dilation is symmetrical because neither you nor the bullet have changed reference frames.
MaxwellsDemon
2.5 / 5 (8) Nov 15, 2015
Urgelt
The primary problem (or one of them anyway) with Kipreos' idea is that his argument presents a paradox. He says you can take any gravitational center to define an Absolute Rest Frame (SR permits the same thing, but extends it to -any- POR, but nevermindthat). Well, if that's true, then sure - we can look at a distant supernova and say "Hey! You're moving at xC relative to my rest frame, so your time dilation is asmmetrical and your clock really is slower than mine, mfer! There's no such thing as "dark energy" after all!!"

But wait-a-minute - Spanky is at that supernova looking back at you, and he's declaring the center of gravity of his supernova to be the Absolute Reference Frame. Oops. Now he declares "No way Alfalfa, my frame is at rest, and *you're the one who's accelerated, so your clock is running slower than mine, byatch!"

"Lemons!" you say, "the only way this works is if the Earth frame is preferred over the supernova frame...now how could that be..."
MaxwellsDemon
2.5 / 5 (8) Nov 15, 2015
Urgelt
You can observe Doppler shift and know there is time dilation. But that doesn't tell you if it's reciprocal.

It does if you accelerate a transmitter and measure the relativistic Doppler shift with a receiver in the rest frame of the lab, and then accelerate a receiver and transmit a signal to it from the lab frame and measure the relativistic Doppler shift again, and find that SR predicts both correctly, which we've done: https://en.wikipe...effect_2
my2cts
2 / 5 (7) Nov 15, 2015

… "mass" is used to mean both "rest mass" and "rest mass + KE/c^2" depending on the context. I don't like the term "relativistic mass" either, because it leads to the kind of confusion that we see in bschotts' comment, but at least it explicitly invokes the total energy. If people would just specify "rest mass" when they mean "rest mass," the pervasive use of "relativistic mass" could finally be eradicated because "mass" would always be understood to mean "total energy / c^2" which would prime students to readily understand the key role of energy in SR and GR.

"Mass" should always mean rest mass, because in Newtonian physics and in the equations of field theory it always does. To entertain two definitions of mass, one of which being redundant, is only confusing.
my2cts
2.1 / 5 (7) Nov 15, 2015
... "rest mass" exists nowhere in the Universe ...

On my side of the universe it does, Benni.
Bloodyorphan
4.3 / 5 (6) Nov 15, 2015
Apparently because of less Gravity, the satellites run faster, and the engineers actually had to slow the atomic clocks so they'd synch with the ground based receivers...
The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day

http://www.astron...gps.html
MaxwellsDemon
1.7 / 5 (6) Nov 15, 2015
"Mass" should always mean rest mass, because in Newtonian physics and in the equations of field theory it always does. To entertain two definitions of mass, one of which being redundant, is only confusing.

Newton was 300 years ago – it's time to let go. We're in an era now where physicists commonly refer to "photon mass" and understand that kinetic energy and fields possess inertial and gravitational mass. "Rest mass" is the special case; it should be the term that requires a qualifier. Otherwise, we'll be stuck with "relativistic mass," and this horrid and interminable semantic debate.
MaxwellsDemon
2.5 / 5 (8) Nov 15, 2015
Apparently because of less Gravity, the satellites run faster, and the engineers actually had to slow the atomic clocks so they'd synch with the ground based receivers...
The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day

http://www.astron...gps.html

Yes, but it would be ~46 microseconds if SR time dilation didn't slow the clocks by ~7 microseconds/day.
my2cts
1.7 / 5 (6) Nov 15, 2015

Newton was 300 years ago – it's time to let go.

I don'y think so.
We're in an era now where physicists commonly refer to "photon mass"

Nobody calls h nu / c^2 "photon mass".
and understand that kinetic energy and fields possess inertial and gravitational mass.

It is the other way around, energy is the source of gravity and inertia. p=Ev nowadays.
Mass is 19th century except for "rest mass" aka "mass". You know, the constant m^2 in E^2=p^2+m^2. Electron, proton, photon mass are fundamental constants AFAIK. Electron, proton, photon energy/c^2 are not.
my2cts
1.7 / 5 (6) Nov 15, 2015

Newton was 300 years ago – it's time to let go.

Copernicus was 400 years ago. Darwin was 150 years ago. Maxwell (your namegiver) was 150 years ago.
A twitterer may think it time to forget about them, a physicists does not.
Benni
3.4 / 5 (10) Nov 15, 2015
... "rest mass" exists nowhere in the Universe ...


On my side of the universe it does, Benni.
.......Ya, I see your problem, you too believe in things that don't exist, Urgeit is having a similar problem because he too does not comprehend why Scientists prefer the term "Relativistic Mass" as opposed to the "Rest Mass" terminology science aficionados such as yourself, Max & Urgeit have declared as their preferred terminology, as erroneous as it is.
my2cts
2.1 / 5 (7) Nov 15, 2015
Regardless of what "Scientists" (why write that with a cap when you're not one of them ?) according to you (hence, not) prefer, you were saying that "rest mass exists nowhere in the universe". See how difficult it is to discuss with you? You divert. Assuming you have a solid observational basis for this statement, I conclude that you are inhabiting another (part of the) universe. What you have no exp basis? Then you are a fool.
my2cts
2.1 / 5 (7) Nov 15, 2015
@ Maxwell, Urgelt
Enjoyed the interesting factual discussion.
Urgelt
1.7 / 5 (6) Nov 15, 2015
Max, will you concede that GPS receivers are not all in the same SR frame? They're moving differently relative to one another and relative to any given GPS satellite.

Maybe Kipreos is overthinking (or underthinking) the question of frames. He wouldn't be the first to be befuddled by Einstein's approach to frames. Look at the confusion right here on rest mass - in a universe where 'rest' is frame-dependent. It's enough to make one's brain hurt.

The way out of the paradox you mentioned is that under ALT, both observers perceive exaggerated time dilation relative to each other; both must adjust their red-shifts to obtain actual relative velocities.

Mind you, I'm not arguing that ALT must be right. I have no idea if it is. But the objection you, and others, have raised, that ALT places Earth at the center of the universe, is bogus. It's a *universal* frame and is expected to work for any observer anywhere.

Probably it doesn't.

But *something* is wrong with theory.
Urgelt
2.1 / 5 (7) Nov 15, 2015
Max, this discussion about frames goes all the way back to Einstein and Lorentz. Einstein ripped Lorentz's preferred framing out of Lorentz's equations. The ensuing arguments still haven't quit.

Tom Van Flanders, U. Maryland, summarized: "...the issue of the need for a preferred frame in nature is, charitably, not yet settled. Certainly, experts do not yet agree on its resolution. But of those who have compared both LR and SR to the experiments, most seem convinced that LR more easily explains the behavior of nature."

http://www.metare...vity.asp

I'm just a member of the lay public, not a physicist. I don't get to declare how nature works. But as a taxpayer, it's not unreasonable for me to ask for deeper experimental investigation into whether cosmologists are correct in their reciprocity assumption regarding cosmological light. Because if they aren't, then dark energy is an artifact of an error.
Enthusiastic Fool
1 / 5 (6) Nov 15, 2015
"Then you are a fool."


Someone call my name? I would have responded sooner but I experienced some time dilation reading down this far.

Based on my reading here it seems like Urgelt is saying the SR portion of the GPS system isn't confirmation of the reciprocal nature. That is that from the GPS sat's frame the Earth clock is slower from GR and SR but from the Earth's frame the GPS clock is fast but not as fast as it should be without SR? Isn't this just a case of the obvious? The GPS sat has a slowed clock rate to account for what the ground perceives as the clock running fast because the data it provides we use in the Earth's frame of reference. Please fix me if I'm being foolish. I think there was an NIST experiment with laser clocks or something that showed SR to hold true even at low velocities. Isn't the reciprocity just that the SR features are invariant in all frames of reference? Every time we replicate SR effects we show that.
Enthusiastic Fool
1 / 5 (6) Nov 15, 2015
Also per Wikipedia GPS receivers also calculate for additional SR effects. This seems to cover the "all receivers aren't in the same frame" argument.
MaxwellsDemon
2.1 / 5 (7) Nov 15, 2015
Urgelt
Max, will you concede that GPS receivers are not all in the same SR frame? They're moving differently relative to one another and relative to any given GPS satellite.

Nope. The ground stations are affixed to the surface of the Earth, so there's no relative motion between them – the ground stations are all in the same reference frame Urgelt : it's called the EIC – "Earth Inertial Coordinate" frame.
MaxwellsDemon
2.5 / 5 (8) Nov 15, 2015
But *something* is wrong with theory.

Something's certainly wrong with Kipreos' theory. But SR and GR? Maybe GR on cosmic scales, but I wouldn't bet on it.

It looks to me like "dark energy" is a physical phenomenon. Either there actually is extra energy in the vacuum (this idea is elegant because GR actually *predicts* the observed acceleration if there's a small energy to the vacuum), or there's a fifth force (physicists loathe this idea because everyone wants to see unification, not fragmentation of the laws of physics) - but there's no reason to assume that we would have known about a force of nature that's so weak that it can only now be detected at cosmological scales. Or perhaps CERN's Dragan Hajdukovic is right, and dark matter and dark energy are artifacts of graviton vacuum polarization.

"Dark energy" isn't proof that our theories are flawed. It only proves that there's something we don't yet understand, and at this point, there's no telling what that is.
Enthusiastic Fool
1 / 5 (6) Nov 15, 2015
Nope. The ground stations are affixed to the surface of the Earth, so there's no relative motion between them – the ground stations are all in the same reference frame Urgelt : it's called the EIC – "Earth Inertial Coordinate" frame.


He did say GPS receivers though not ground stations. Your car GPS is a GPS reciever and it's certainly not in a fixed location with a fixed speed in relation to the GPS sats. Even if the reference stations on the ground are not moving with respect to one another(they are slightly through tidal forces etc but this averages out) they are moving differently with respect to the GPS satellites. Some are moving into the footprint of the sat and some are moving out. We measure positioning using a geodetic datum where position in xyzt is derived in relation to the center of the Earth. Since each receiver is moving in a different direction relative to the satellite how can we use a singular reference frame for all?
Enthusiastic Fool
1 / 5 (6) Nov 15, 2015
To clarify, EIC is neccessary for positioning of the satellites and receiver positioning is in reference to that but this is not used as the frame of reference relative to the satellite. Both the satellite and the receiver positioning can be mapped using EIC but that doesn't determine the reference frame of the reciever relative to the sat otherwise terrestial measurement of SR would be impossible as everything is in the same frame, right? Using the whole Earth as a collective frame of reference may be appropriate for interstellar scales but not useful for measuring position on the human scale. Your positioning can be no more precise than the size of your reference frame, right?
MaxwellsDemon
2.1 / 5 (7) Nov 15, 2015
Enthusiastic Fool
My mistake: I meant to say that the ground stations are all in the ECEF (Earth Centered Earth Fixed) reference frame. I had the EIC frame on the mind because it's the same frame that Kipreos defines as an "Absolute Reference Frame."

The ground stations are at rest with respect to the ECEF and the satellites are in motion wrt it. Most users are essentially at rest wrt to the ECEF since ground velocities are so small, but the incredible precision of the GPS system permits ground velocities to be determined quite accurately. This paper offers a good overview of the system:
http://relativity...olor.pdf
Urgelt
2.1 / 5 (7) Nov 16, 2015
EF, welcome to our civil and mind-bending conversation!

Max, EF, the ECEF is from GR, not SR. Yes, on the surface the receivers are all in the same frame for GR purposes - at the same depth within a single gravity well. I hope we aren't confusing that with SR's time dilation from relative motion, which is thought to be independent of GR effects..

I interpreted Kipreos to be saying that the Absolute Lorentz Transformation is not the same as the ECEF, and that it works for observers in all locations and velocities. That's a tough sell, but not as tough as declaring the Earth to be the center of the universe.

Max, if you're right and dark energy is a real phenomenon, our theories completely missed whatever it is. You could drive a quasar - and more - through a flaw that big. It's easier for me to suspect a smaller flaw in our understanding of relativity, which is hard rowing even for the experts.

We need more evidence to nail it down either way.
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
Enthusiastic Fool
Since each receiver is moving in a different direction relative to the satellite how can we use a singular reference frame for all?

Because the motion is measured relative to the ECEF reference frame. For positioning, the motion component is irrelevant because you're simple determining your coordinates at a given instant wrt to the satellites.
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
Urgelt
Max, EF, the ECEF is from GR, not SR.

No, it's for SR, not GR. SR is all about relative motion. GR only applies to altitude and some other minor deviations in the GPS system. All of which are carefully accounted for by the DoD to provide a "clean" ECEF reference frame to work with.

Yes, on the surface the receivers are all in the same frame for GR purposes

And for SR purposes also.

I interpreted Kipreos to be saying that the Absolute Lorentz Transformation is not the same as the ECEF

Now you're getting it mixed up: the frame Kipreos employs appears to be identical to the ECI frame. Of course, declaring that to be a universal absolute rest frame would be insane, but he stops short of doing that by claiming that Any non-rotating center of gravity frame is somehow a part of his crazy "absolute rest frame" idea. I say "crazy" because all centers of gravity are in relative motion, so that puts us back at square one, with SR, which actually works.
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
Max, if you're right and dark energy is a real phenomenon, our theories completely missed whatever it is.

Yep. That shouldn't surprise us. The dark energy effect is very weak and acts across unprecedented scales of observation. We often find new physics when we exceed the reach of previous observations.

You could drive a quasar - and more - through a flaw that big

Not really. Until we have a unified field theory, we should expect the universe to have some surprises in store for us at new scales/energies/etc. On the other hand, somehow missing a key flaw in SR for a century, now -that- would be a staggering flaw, because we've tested it exhaustively.

It's easier for me to suspect a smaller flaw in our understanding of relativity

Kipreos' claim isn't about a "small flaw," he's claiming that SR is fundamentally wrong. Which is absurd. Physicists have tested it every which way, including sideways via the transverse Doppler effect, and it's always right.
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
We need more evidence to nail it down either way.

No we don't. More tests at the extremes are always a fine idea, but we already have a mountain of evidence that refutes Kipreos' assertion. SR has successfully spawned quantum electrodynamics, and it's employed daily at every particle accelerator in the world, and gives us a beautiful and deeply logical, albeit counterintuitive, model of flat spacetime that accurately describes everything from time dilation to Lorentz contraction to relativistic energy and the relativistic velocity addition equation. It's every bit as solid as the quantum mechanics that our computers are using right now.

If Kipreos had understood SR, he wouldn't have written that paper. He's wrong. We have the evidence to prove it. It's a flawed idea and honestly I'm tired of talking about it.

Thanks for a stimulating and congenial chat, gents; it's been fun ;
Urgelt
2.1 / 5 (7) Nov 16, 2015
Max, I admit, my understanding of SR is very far from complete. But I do think SR is independent of gravity wells, and that its frames of reference have nothing to do with them.

I've been wrong before, however, so my confidence level is low.

I'm comforted by Van Flanders, an actual physicist and peer who is willing to admit that how frames work in SR is subject to a continuing and vigorous debate among physicists. That alone should tell you that more experimentation is needed to complete our understanding of relativity and its frames.

Similarly, my understanding of SR isn't deep enough to let me dismiss Kipreos out of hand. Peers seem to be doing that without a second thought - that does lend weight to your own dismissal of him. Yet I'll go with Van Flanders when he says that Lorentzian Relativity seems to explain many observations a little better than SR does. Which doesn't make LR correct. But SR is not nailed down as tight as you seem to think it is.

Enjoyed it!
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
Urgelt
You mean Tom Van Flandern. Van Flandern was a good astronomer, but probably the worst theorist in academic science. I've had nightmares about a guy like him advocating my work. A partial list of his embarrassing foibles includes; lecturing on the virtues of the defunct LeSage theory of gravity ("ultra-mundane corpuscles" and all), resurrecting an incorrect argument to calculate a "speed of gravity" 10^10 times the speed of light (we know it's actually c within observational error), and writing a book that declares that the "face on Mars" to be an artificial structure created by "the Builders" who inhabited Mars when it was a moon of a watery "Planet V" that exploded 3.2 million years ago to form the asteroid belt, in which he says:
So I leave you with the thought that there may be a grain of truth in The War of the Worlds, with the twist that WE are the Martians.

Some more than others, it seems.
https://en.wikipe...Flandern
Enthusiastic Fool
1 / 5 (6) Nov 16, 2015
Hi Max,

I don't agree with Urgelt about "needing more evidence" for SR. However, I don't think you have the GPS thing quite right. When not performing a movement and in a heathly status the GPS sats are fixed WRT to the Earth Inertial Coordinate frame "flying" at known positions in that coordinate system. They periodically update their ephemeris to reflect any changes of position. Your receiver is not in a fixed position WRT the ECICF. You are using the known positions of 4 sats and their relation to you to trilaterate your position. All the sats are not moving relative to one another and they fit in the ECICF. Your vehicle or reciever is in its own frame of reference moving on an independent path from the ECICF. This is why adding a second receiver in its own frame of reference to a given position increases precision.
MaxwellsDemon
2.1 / 5 (7) Nov 16, 2015
Enthusiastic Fool

The ECI is used to sync the satellite clocks wrt each other, and wrt the ECEF which is the navigational basis of the GPS system. The satellites are revolving around the Earth with half the period of a point on the Earth's surface so they're not fixed wrt either the ECI or the ECEF:
Orbiting about 20 000 km above Earth's surface, all the satellites have periods of 11 hours and 58 minutes. Because that's half a sidereal day, a fixed observer on the ground will see a give· satellite at almost exactly the same place on the celestial sphere twice each day.

https://www.uam.e...vity.pdf

Most of the satellites also move wrt each other:
https://www.youtu...yeGcpoyE
MaxwellsDemon
2.7 / 5 (7) Nov 16, 2015
Haha - we got down-voted by a sock puppet Urgelt! That's never happened to me before, but it's surprisingly validating. Like my father used to say "A man's worth is measured by the caliber of his friends...and the cowardice of his enemies." So true ;
Mimath224
5 / 5 (1) Nov 16, 2015
MaxwellsDemon, Urgelt, well I enjoyed, and learned a bit more, from your discussions and thought you both deserved a little help there. Objective intelligent discussions impress me and sometimes I get a bit tired of the 'name calling' and I all too glad to hear arguments by people who have a working connection to SR an GR...because I don't; what 'I know' about it is from what I read. Keep up the good work!
MaxwellsDemon
3 / 5 (6) Nov 16, 2015
You're a good egg Mimath224; I'm glad you've enjoyed this debate, and thank you ; Here's a tip that you'll enjoy if you decide to delve into SR: the Lorentz transform that describes time dilation, relativistic mass, and length contraction, is nothing more than the equation of a circle. If you place v/c on the y-axis of a unit circle, the x-axis gives you the Lorentz transform. It's so simple and beautiful.

Enthusiastic Fool
I was a bit curt with you - I apologize. While I marvel at the technical sophistication of the GPS system, my only real interests in it are the underlying physical principles. So as much as I enjoy discussing those (SR and GR), I dislike taking detours into the intricacies of applied technology. I'm sure I've made any number of errors on the fine points of the GPS system for that very reason, and you're right to correct me on those.
MaxwellsDemon
2.6 / 5 (5) Nov 16, 2015
Urgelt
I found an interesting discussion of Lorentzian Relativity at Physics Forums that you might enjoy. Apparently the equations are identical to SR in practice, although LR explains them differently (by employing an "aether" rest frame of reference), so ultimately they're equivalent computationally. In light of the CMB rest frame, the validity of the LR interpretation looks perfectly supportable. But Kipreos' ALT theory is distinct from LR, and it's those differences that undermine its credibility, imo. You may find this discussion enlightening, as I have:
https://www.physi....298185/
Urgelt
2 / 5 (4) Nov 17, 2015
Max, yes, ALT is distinct from LR, very true. Both assume a universal spacetime frame. LR posits aether. ALT does not. When Lorentz was active in physics, it was quite popular to presume that light waves require a medium, like sound waves do. Kipreos, at least, is not trying to take us back to that. But he does invite us to reconsider a universal frame.

SR forbids it. But I'm not as ready as you are to assume that SR perfectly describes relative motion.

Van Flandern has a track record! I didn't know that. Still, in science the test that counts is evidence, not trust in authority. We do not decide whom to believe, we decide what the evidence means and look for more.

At least some talking heads in physics are open to the possibility that SR may have imperfections. Cooking up new ways to test SR is good science, isn't it? Find a hole in it, and new physics will pour out. Confirmation is a good outcome, too.
Urgelt
2 / 5 (4) Nov 17, 2015
I visited the link you furnished, Max. That is some seriously fun conversation taking place over there! I'm going through it now. Thank you!

So some folks are tossing around the notion that quantum nonlocality opens the door to some of Lorentz's ideas.

Maybe we needed reminding: in the absence of reconciliation between relativity theory and quantum mechanics, none of the above can be considered complete. There's still work to do.

My prescription is more experiments!

Cue groans.
Mimath224
not rated yet Nov 17, 2015
@MaxwellsDemon, thanks for the tip. I have several SR books (Bondi, Bohm etc.) and other physics texts that include SR & GR. Some give the tanh(beta) diagrams. Again, unit circles are so easily understood that I can't believe that I read some real rubbish texts refuting SR. More fool me for wasting my time eh? I don't mind if some try an alternative theory that is both readable and intelligible but it seems to me that there are some that like to 'bash' Einstein by changing this and that and then say Einstein got it wrong.
Okay, history is replete modified theories, new insights an so on but it takes a long time and doesn't happen overnight. One only has to look how long it took to get to F = ma from early Greeks trying understand the 'push' and 'pull', Aristotle, Strato's motion, Philoponus, J. Buridan's impetus, Galileo and finally Newton (sorry to bore with the obvious). Do we need a n t of g? Maybe in say, X00 years SR & GR might be modified but they're doing okay right now.
MaxwellsDemon
1.8 / 5 (5) Nov 17, 2015
Urgelt
LR posits aether. ALT does not

LR doesn't require the aether propagation mechanism to be true for its equations to hold true. The CMB suffices quite nicely as a substitute for an aether frame. ALT isn't even logically self-consistent, as I've pointed out.
But he does invite us to reconsider a universal frame. SR forbids it

SR only forbids a preferred universal frame. That's a crucial distinction.
Van Flandern has a track record!

It's true that his abysmal track record with other theories is irrelevant if the evidence supports a different argument. But I don't see that evidence. And he never advocated for ALT; he advocated for LR, so it's moot anyway. I wonder if any physicist supports ALT. Probably not.
So some folks are tossing around the notion that quantum nonlocality opens the door to some of Lorentz's ideas

I'm glad you're enjoying that thread. Nonlocality seems to be just as big a problem for LR as SR so I don't see their point
MaxwellsDemon
1.8 / 5 (5) Nov 17, 2015
Urgelt
There's still work to do.

That's certainly true. But SR has already been fundamentally integrated with QM, and SR explains things like the relationship between electrical charge and magnetism perfectly. So I think it's about as likely that SR is wrong, as it is that arithmetic is wrong. The real hold-out is quantum gravity, but that may or may not illuminate the question of dark energy.
MaxwellsDemon
1.8 / 5 (5) Nov 17, 2015
Mimath224
More fool me for wasting my time eh?

Not at all! I try to study every new idea that comes down the pike – there's no better way to understand physics than examining each assumption from every angle possible; even the seemingly crazy questions teach you lessons along the way. And it keeps your creative mind pliable, like a gymnast stretching before practice. One such idea spurred me to spend six months poring over every SR equation and experiment with a fine-toothed comb, looking for an alternative interpretation or oversight. In the process, I learned the beauty, the explanatory power, and the enormous experimental edifice supporting SR. Science is born of impertinent questions – never turn your back on your inner rebel Mimath224 (but never let him get away with shoddy/lazy/incomplete reasoning either) ;
Urgelt
1 / 5 (3) Nov 18, 2015
Max, isn't it more accurate to say Lorentz's mathematical formalisms conforms with 'the relationship between electrical charge and magnetism perfectly? They're used in both SR and LR.

Nonlocality in QM does seem to cast at least a little doubt on the SR interpretation, since SR insists that synchronization of time is limited by the speed of light, which is the reason Einstein discarded a universal frame, where QM shows simultaneity irrespective of distance to be a part of how the universe works.

At the least, LR isn't dead, as it functions as well as SR predictively.

Something I have noticed about physicists: there are - approximating - three tiers. The bottom tier are people like me who read and discuss but are far from experts. The second tier are people who actually know a great deal - teachers, researchers - but approach the subject with too much certainty.

The top tier understands not only what is known, but the shape of the unknown. They see the holes.
Urgelt
1 / 5 (3) Nov 18, 2015
Of course some holes are obvious enough to smack even people like me in the forehead, like the place holder we call 'dark energy.'

Seeing holes in Einstein's view of simultaneity and framing is harder. But while the Lorentz Transformation indisputably works for both SR and LR, we still have little experimental evidence to prefer one over the other. And LR has a very different view of simultaneity and frames.

There's got to be more to learn. And the questions are big enough that we could find some large (translation: exciting) surprises.
Mimath224
5 / 5 (1) Nov 18, 2015
@MaxwellsDemon I'm sorry but I voted you 5 on your previous 2 posts yet I see it has appeared 1/5. I apologize.
MaxwellsDemon
2 / 5 (4) Nov 18, 2015
Max, isn't it more accurate to say Lorentz's mathematical formalisms conforms with 'the relationship between electrical charge and magnetism perfectly? They're used in both SR and LR.

Urge, as I understand it, LR is just SR from the POV of a universal rest frame postulated to be the infamous "aether." The CMB frame obviates the need for an aether, which reduces LR to a special case of SR. I'll have to look at LR more closely to be sure about this, but I don't see how the two theories can make the same predictions otherwise.
SR insists that synchronization of time is limited by the speed of light, which is the reason Einstein discarded a universal frame

Iirc, Einstein tossed the aether mainly because it's superfluous. In any case, simultaneity is frame dependent, so entanglement poses the same problem for LR that it poses for SR, as far as I can tell. Does LR offer a mechanism for instantaneous action at a distance?
MaxwellsDemon
2 / 5 (4) Nov 18, 2015
The top tier understands not only what is known, but the shape of the unknown. They see the holes.

I agree. But the top tier can discern the holes in theory from the holes in their understanding. Kipreos has the two mixed up. Leonard Susskind is the kind of "top tier" physicist who not only see the gaps, but also understand the types of bridges that can span them. It takes a lot more than a couple of years of tinkering to achieve that kind of insight.
Of course some holes are obvious enough to smack even people like me in the forehead, like the place holder we call 'dark energy.'

I think it's premature to call "dark enrgy" a "hole" in our theories. It could be that we've simply failed to apply GR properly, or an altogether different phenomenon. It's always a bad idea to hitch your cart to any horse before you know where you're going. We need a new generation of high-precision data on dark energy before we can discern its true nature, imo.
MaxwellsDemon
2 / 5 (4) Nov 18, 2015
@MaxwellsDemon I'm sorry but I voted you 5 on your previous 2 posts yet I see it has appeared 1/5. I apologize.

No sweat Mimath - ScienceX just dropped the member ranking system, so the scoring only applies to the filter now. And we've been so far off-topic through most of this that it's probably best to down-rank all of my posts here anyway ;

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