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I've been doing a fair amount of research of original material, and the picture of general relativity that I get seems to be very different to what I was taught.
For example, people tend to say the speed of light is constant, and Einstein said it. But it isn't true. Yes, he started with this as a postulate in 1905, but in 1911 he wrote On the Influence of Gravitation on the Propagation of Light, where we can see his ideas evolving as he talks about c = c0 (1 + Φ/c˛). Then in 1916 in section 22 of Relativity: The Special and General Theory he talks further: "In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)".IMHO people tend to see the word velocity in the 1920 translation without seeing the context. Many skip over his reference to "one of the two fundamental assumptions", and don't see that he's talking about a serious issue with the SR postulate of the constant speed of light. Many do not realise that Einstein didn't speak English in 1916, and what he actually said was die Ausbreitungsgeschwindigkeit des Lichtes mit dem Orte variiert. This translates into the speed of light varies with the locality. He was saying the speed varies with position, hence the reference to that postulate. And what he also said, is that this causes the light to follow a curvilinear path like a car veers when the near-side wheels encounter mud at the side of the road.
People often react badly this.
People think Einstein told us about curved spacetime, but when you read The Foundation of the General Theory of Relativity, incredibly, it's just not there. Yes, he talks about geometry and curvature and space-time, but he's giving the equations of motion, through space.
He doesn't talk about "motion through spacetime" like people do these days.
But perhaps the signal most important thing most people don't know, is that whilst aether is a taboo word which is most definitely out of the mainstream, Einstein's gave his Leyden address in 1920. And the title is Ether and the theory of relativity. There's Einstein, talking about space and calling it an aether: "Mach’s idea finds its full development in the ether of the general theory of relativity. According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that ‘empty space’ in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν), has, I think, finally disposed of the view that space is physically empty".
What's especially surprising is how similar it is to the way Newton described it in Opticks:Doth not this aethereal medium in passing out of water, glass, crystal, and other compact and dense bodies in empty spaces, grow denser and denser by degrees, and by that means refract the rays of light not in a point, but by bending them gradually in curve lines? ...Is not this medium much rarer within the dense bodies of the Sun, stars, planets and comets, than in the empty celestial space between them? And in passing from them to great distances, doth it not grow denser and denser perpetually, and thereby cause the gravity of those great bodies towards one another, and of their parts towards the bodies; every body endeavouring to go from the denser parts of the medium towards the rarer?" queries 20 & 21The language is different, but the underlying concept is the same. The energy tied up as the matter of a planet "conditions" the surrounding space to create a non-constant gμν along with a gradient in c which causes curvilinear motion. To many people this is unacceptable, because it isn't what they've been taught. It doesn't matter that it comes from Einstein and Newton and is supported by experimental evidence, they refuse to believe it.
Show them two astronauts carrying parallel-mirror light clocks at different locations, and they will refuse to admit what the different readings on those light clock is telling them.
Why is it that people seem unable to see what Einstein actually said, or the evidence that supports it?
Claiming that my mathematics or education is lacking or that I've been repeatedly banned doesn't make up for sincere discussion of this important matter.
It's quite clear what Einstein said, and my astronauts example is fully supported by the GPS clock adjustment and the Shapiro time delay.
All: see http://arxiv.org/abs/physics/0204044 for Einstein's Gravitational Field by Peter M Brown. It's a very interesting paper, well worth reading:
Refraction is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another at an angle. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth...Wikipedia: Refraction
There is a local expression of forces (evanescent field) and a distant expression of forces (far field). The local expression of forces are in the near field and are associated with the notion of "virtual particles" in which the fluxes of "field lines" associated with the sources are not "detached from their sources"
It is an interesting point to ponder that aside from the fact that light travels at the speed of light and is simultaneously affected by electrodynamics and also by gravity and "falls" identically like a projectile along the "surface of spacetime" and is a "limiting case of material projectiles" as V -> C. This suggests there really is not action at a distance dependent on the mutual mass between particles since such a theory would mean that if one of the two "attractive" objects was of zero rest mass there would be no "attraction" at all. It is possible to demonstrate very effectively that photons have zero rest mass. So... photons "fall" like a very light stone that is traveling infinitely close to the speed of light.
Gravity is deemed "symmetric" (unipolar) while electromagnetism is "anti-symmetric" (bipolar). We often discuss "forces" when we deal with these two different phenomena but the theory of forces cannot account for this alone since "forces" are actions at a distance while everything appears to point to an explanation due to the interaction between "particles" which depends on their mutual interactions. I would point out "a particle" is also a paradigm that might be hindering our ideas about "forces".
That "primary force" of gravity and the "primary force" of electromagnetism (charge and magnetism) do not appear to be primarily the result of the exchange of "force carriers" or due to continuous accelerations in the matter or charge sources. Einstein thought of gravity as a pseudo-force and is explained by his local theory of spacetime curvature.. his "General Theory of Gravatation" (ED: spacetime was a concept Minkowski invented not truly Einstein's own original idea but "near enough").
This was summed up by John A. Wheeler as "Matter tells space how to curve, and space tells matter how to move".
Action at a distance for these "gross effects" is not required. A simplistic view of this concept is like a skateboard in a skateboard park.. the board moves according to it's velocity and the curvature directly under it's wheels at each instant in time and does not require the concept of a "distant source of force" attracting the skateboard be needed to explain it. That was another visual analogy so do not think too much about that simple notion.
Likewise gravity "appears" to not require distant forces to motivate the gross motion of planets of the rotation of galaxies... it gets it "moving orders" from the local curvature of spacetime. The complementary particle to the photon... the graviton would then play the same role as a photon in electromagnetism and would involve "real" gravitons but gravity... that we measure mass by using a set of scales... plays the same role as the electromagnetic forces we see in magnets electric motors and moving charges of various types... the mass "fluxes" (like the electromagnetic fluxes) remaining attached to the "sources" (whatever they are)and neither "primary force" requires propagating light or propagating gravitons. what I mean by this in the case of gravity curved spacetime explains the motion of celestial bodies while in electromagnetism charged particles (and magnetism) and their quasi-stationary fields explain the "forces" between charges. Each of these phenomena might appear to be separate and acting on different "manifolds" but a theory of combing these manifolds was Einstein's dream and is the base motivation for current String Theory today. The distant influence of both gravity and light due to carriers of force require the idea of accelerations in the sources generating these particles. There are some problems with all these theories.
I am not "undervaluing" the influence of light since almost everything in the universe we can sense is the effect of either quantum electrodynamics or of gravitation. The other forces (weak, strong forces) are not essential for the things we appreciate (may also be even detrimental) on a day to day basis and are involved with "nuclear radiations" of various kinds... so "light" and therefore photons in all their forms are very important to the way our world works... both real photons and virtual photons in all the forms of the motion of sources of the apparent permanent charge. Of course matter also plays a role in there as "mass" and as "matter waves" but this is not explained by QED.
Now returning to the core issue... Regarding the curvature of spacetime in the General Theory of Gravatation it might be "directly compared" with the property of optical diffraction in refractive materials. So instead of speaking about curved spacetime and Einstein had spoken in terms of a "gravitational refractive index" then this would effectively embed "matter" in an unseen medium whose property was to alter the speed of light rather than "warp some kind of unseen membrane" which we currently identify as "mass". The optical refractive index of a medium is a reflection of the speed of light through the medium and the speed of light in a vacuum.
With gravity we cannot see any medium so we usually do not invoke a material medium to "conduct" gravity. None has ever been detected. Still... as a pure paradigm it "might be useful" to consider this property as if it did exist. This phenomenon exhibits "optically" as Einstein's Rings and we might like to consider spacetime curvature having a variable gravito-optical density reflecting and paralleling the idea of warping of a membrane. But are refractive index and a hypothetical gravito-optical density the same... No... But why not? That is a very interesting question.
We actually cannot verify the existence of either a "physical spacetime" or a vacuum refractive index altering material properties existing in the empty space around matter... That might be interpreted as a vacuum energy density in some way. This really is not a required part of the Einstein's Theory since all theories have their paradigms and they are taken up or discarded when required. What is important is we all realize that, while the paradigm assists us in visualizing the phenomena, it should not be thought of as the only way of understanding it and the future of science will change it's paradigms more often than some may want. The mathematical description of the theory should be attempting to describe this "mental picture" we have developed of these "forces" but do not be surprised when an experiment changes the results of some of the theory the paradigm is radically modified to account for these perceived conceptual anomalies.
As an additional point... There is very little differentiating "virtual" photons from "real" photons since photons can be created on demand and a sufficiently energetic process can produce these "real" photons from a source embedded in "virtual" photons... A radio transmitter is a source such as this... even the transitions in an atom can produce photons from virtual photons.
On the other hand it is still to be shown experimentally that gravitons really exist to enable the analogy between the photon and electromagnetism and the graviton and gravity to be extended into an overall paradigm.
Far, my understanding is that frame dragging occurs only if an object or particle is spinning. If the Earth had no rotation, an object placed anywhere on a sphere two hundred thousand kilometers from the Earth would experience the some magnitude and direction of acceleration as an object placed anywhere on that sphere.
Elf, Einstein spent the last thirty years of his life trying to unite electromagnetism and gravity. Some materials will block certain frequencies of the EM spectrum but no material, we know of, will block infrared. The best thermos bottle ever made, even with a complete vacuum, will have some infrared EM. There is no place in the Universe, man made or natural, where there is no radiation.
I would ask one question of Phys, can he show us one cubic nanometer of space that does not contain radiation in the Universe? If the answer is no then it could be said that radiation is the aether of space.
I would ask one question of Phys, can he show us one cubic nanometer of space that does not contain radiation in the Universe? If the answer is no then it could be said that radiation is the aether of space
Quote from: Good ElfIt is an interesting point to ponder that aside from the fact that light travels at the speed of light and is simultaneously affected by electrodynamics and also by gravity and "falls" identically like a projectile along the "surface of spacetime" and is a "limiting case of material projectiles" as V -> C. This suggests there really is not action at a distance dependent on the mutual mass between particles since such a theory would mean that if one of the two "attractive" objects was of zero rest mass there would be no "attraction" at all. It is possible to demonstrate very effectively that photons have zero rest mass. So... photons "fall" like a very light stone that is traveling infinitely close to the speed of light.Not quite, Good Elf! Maybe you were keeping it simple, but see that squared-off circle representing a single electron? It's deflected half as much as light: ←↓ ↑ →
As described by Wheeler in the early 1960s, geometrodynamics attempts to realize three catchy slogans * mass without mass, * charge without charge, * field without field.
I was keeping it simple...
I note your point though... Clearly the photon does bear "topological charge"... the twisted strip model shows one way in which this "charge" in permanently charged particles may arise. This would go a long way to realizing JA Wheeler's "dream" of geometrodynamics...
The electron in the theory discussed in Williamson and Van der Mark's paper deals with a permanent topological charge in a very energetic optical vortex. These vortices may be created "in the wild" (recent papers have discussed the creation of these entities using simple holograms) and maybe they are stable quantum "resonant" entities with requisite properties of stability. It is possible to explain the charge using this model but it is more difficult to explain mass.
Speculation: Mass appears to be related to the Orbital Angular Momentum of the internal photon exhibiting as an "external" mass which is linked directly to the conservation laws of CPT symmetry.
Your comments noted, PhysBang. But it isn't "my theory". All I've done is researched genuine historical material and bona-fide peer-reviewed papers.
Einstein really did talk of a non-constant guv that causes curvilinear motion along with the aether of general relativity.
The modern interpretation of general relativity genuinely seems to paint a different interpretation to Einstein's, and mathematical exercises just don't assist our discussion.
No, it really is your theory because you are making claims about experiments and observations that contradict what every scientist who uses relativity theory claims. For example, you say that relativity theory, if used "correctly", will produce the right rotation curves for galaxies. However, every scientist working in astronomy and astrophysics says that this doesn't happen.
When you say this, you are obviously ignoring what Einstein said about the aether. You even ignore what the author of the page hosting your favourite link to Einstein's address says about that address. This author writes on the page, "This address has been frequently misunderstood as positing that a return of the ether theory." Anyone who reads the address or the page must see that Einstein is clearly rejecting the standard idea of an aether theory in favour of, at best, an idea that bears only one feature of an aether theory, that of being a medium.
We are not talking about mathematical exercises, we are talking of the actual content of the theory. When you say that relativity theory does away with the need for dark matter, you are making a claim about actual values that are measured and actual values that are calculated. You have shown no way to reconcile these values. If you have a way to reconcile these values, you should share it. If you have no way to reconcile these values, you should retract your claims.
You need to show exactly how "a non-constant guv that causes curvilinear motion along with the aether" produces the calculations for the rotation curve of a galaxy and how this calculation matches up with the observed rotation curve.
An astronomer or an astrophysicist who makes a claim about dark matter backs up her or his claim with the relevant observations and calculations.
I note that you have retracted some of your previous claims. For example, you have removed your two calculations of the size of the universe from your public document version of your theory, two calculations that differed by several orders of magnitude. Many actual scientist retract claims when they have made an error. If your claims about dark matter are in error, it is no shame to retract them.
As for "every scientist", you should read Mordehai Milgrom's New Physics at Low Accelerations (MOND): an Alternative to Dark Matter at http://arxiv.org/abs/0912.2678. Note page 4 where he says:"We see that the modification of GR entailed by MOND does not enter here by modifying the ‘elasticity’ of spacetime(except perhaps its strength), as is done in f(R) theories and the like."
I've merely stated the obvious. Einstein told us that a gravitational field is a region of inhomogeneous space, and we all know of the raisins-in-the-cake analogy for the expanding universe. Space expands between the galaxies but not within, giving rise to another source of inhomogeneous space. According to Einstein, that's a gravitational field, with no causative matter. I really can't see why you have such a problem with this.
I'm not obviously ignoring anything, I'm reporting what Einstein said. He talked about a non-constant guv that causes curvilinear motion, and he talked about the aether of general relativity. See http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm. What more can I say? There it is, in black and white.
Quote from: PhysBang on 28/01/2010 02:17:57We are not talking about mathematical exercises, we are talking of the actual content of the theory. When you say that relativity theory does away with the need for dark matter, you are making a claim about actual values that are measured and actual values that are calculated. You have shown no way to reconcile these values. If you have a way to reconcile these values, you should share it. If you have no way to reconcile these values, you should retract your claims.No I shouldn't. We have free speech in science, and observations and comments are permitted.
Quote from: PhysBang on 28/01/2010 02:17:57An astronomer or an astrophysicist who makes a claim about dark matter backs up her or his claim with the relevant observations and calculations.But even to this day, no astronomer or astrophysicist can provide conclusive proof for the existence of dark matter. It remains the subject of debate. And since it was first proposed by Zwicky seventy three years ago, we are surely free to discuss alternatives. People are discussing them more, and proposing experiments, see for example Testing MOND/TEVES with LISA Pathfinder by Christian Trenkel, Steve Kemble, Neil Bevis, and Joao Magueijo at http://arxiv.org/abs/1001.1303.
The widely examined and accepted cosmological models are not relevant here. I have a problem with your claims because you are denying the facts. The facts are that the rotation curves of galaxies do not work out unless we include dark matter. Please show us, and the entire scientific community including Milgrom, how standard GR can produce the rotation curves of galaxies without the need for dark matter.
Perhaps you failed to notice that this proposes a modification of GR. Do you propose a modification of GR...
I report Einstein's statements: a gravitational field is a region of inhomogeneous space caused by a concentration of energy tied up the matter of a planet, which in turn causes the curvilinear motion that is described as curved space-time.
I don't deny the facts of general relativity, I report them.
Physbang: see http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm"According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν).."Einstein said this in 1920, and he talked about curvilinear motion in The Foundation of the General Theory of Relativity in 1916. The theory I offer is Einstein's relativity. I'm not denying the facts.
PhysBang, let's keep ad hominems out of the forum. Such as accusations of dishonesty and promoting ignorance.
Talk to the facts, and only the facts, such as those on public record. Offer your interpretation, if you wish, be specific, then let the readers decide for themselves if there is any distortion going on.
Physbang: I'm afraid it isn't a small subset of the available literature. In 1911 Einstein wrote a paper "On the Influence of Gravitation on the Propagation of Light" where he said "If we call the velocity of light at the origin of co-ordinates c0, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = c0 (1 + Φ/c˛).". See http://www.relativitybook.com/resources/Einstein_gravity.html for an online version.
All you have to do is look at the original material to understand that the modern interpretation of relativity is different to Einstein’s, and appreciate that this then causes misunderstanding.
Hence the article says Einstein’s variable speed of light makes sense, and doesn’t make sense.
Why, if you want to defend a point about general relativity, are you looking at things Einstein wrote before general relativity?
Since you seem to want to use the 1911 theory as representative of Einstein's theory, please show us using this theory where Einstein uses an aether.
OK, so please demonstrate how, using the 1911 theory or the later theory, the rotation curve of a galaxy doesn't produce a measurement of dark matter.
...As the authors note, the constant speed of light is fundamental to the way that general relativity determines causal structure.
Thus it is conceptually more fundamental than the time it takes for light to cross a certain distance in a certain time in a certain particular system of coordinates. This is particularly true since the correct description of any physical system in any well-formed set of coordinates in general relativity must maintain this causal structure.
The most well known system of coordinates in general relativity with what one might call a variable speed of light is that associated with the Friedmann equations. These equations provide a solution to the Einstein field equation and the form the basis of a family of cosmological models preferred by Einstein after 1929 and survive in a modified version in contemporary cosmology.
In these solutions, light can travel faster than light, because over time the distance between where the light left and where the light is received can get larger. However, one should recognize that this is not a way to measure speed that is representative of the causal structure of the universe...
..and when one takes that into account properly, one finds the speed of light as constant.
Despite working with, and accepting as approximately correct, the Friedmann models, cosmologists do not run around saying that the speed of light is variable.
Phys, does the rotation curve of galaxies guarantee the existence of dark matter? I would think that a logical mind must realize there is the possibility of another explanation even that one of our fundamental tenets may be wrong.
One more question phys and I will explain after your answer. Suppose that the result of the BB was the creation of a single proton and no other particles, how much space would be created for that proton?
To demonstrate that I'm not cherry picking. We see Einstein repeatedly telling us the speed of light is variable.
Quote from: PhysBang on 03/02/2010 13:27:36Since you seem to want to use the 1911 theory as representative of Einstein's theory, please show us using this theory where Einstein uses an aether.I don't. Plus I've already shown you the 1920 Leyden Address where Einstein talks of the aether of General Relativity.
I politely decline on the grounds that such a laborious exercise is unnecessary in the light of Einstein's description of a gravitational field as inhomogeneous space, along with our current knowledge of the expansion of the universe. Space expands between the galaxies, not within. The result is inhomogeneous space, and that's a gravitational field with no causative matter.
It is at odds with Einstein, who described the central concentration of energy tied up in as the matter of a planet causing a conditioning of the surrounding space described via a non-constant gμv which causes a variable speed of light that then causes the curvilinear motion that is described as curved spacetime. I've paraphrased, but read the original material, and you will find that I am correct.
No, I'm afraid it isn't. What's conceptually more fundamental relates to what we actually observe. We don't observe time passing, our seconds are defined using the motion of light. Thus when our second changes, it's because the rate of motion of light has changed.
Quote from: PhysBang on 03/02/2010 13:27:36Despite working with, and accepting as approximately correct, the Friedmann models, cosmologists do not run around saying that the speed of light is variable.But I'm afraid some do. See for example http://en.wikipedia.org/wiki/Variable_speed_of_light and http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.4507v1.pdf where Magueijo and Moffat responded to Ellis. Its constancy has become a tautology.
I've given you ample Einstein quotes PhysBang, enough to demonstrate that I'm clearly not cherry-picking, and the hoary old "out of context" does not undo what Einstein actually said.
Here's the deal re dark matter, as simply as I can put it: it's energy that causes gravity, not matter. Matter only causes gravity because of the energy content. Einstein told us that a gravitational field has energy, and that a gravitational field is a region of inhomogeneous space. Now take a region of homogeneous space and divide it into cubes. Now decrease the energy-density of all of the cubes bar the one in the centre. The result? An energy-density gradient all around it. A gravitational field. But try as you might, when you look in that central cube, there's not a single speculative WIMP, there's no dark matter there. Because the dark matter you're looking for, is space itself. It's dark, it has energy, it isn't moving with respect to you, and E=mc2.
My gedanken about the single proton should be enormously important for anyone who thinks about it's meaning. THE EXPANDING ELECTRIC FIELD OF THE PROTON IS THE AETHER OF SPACE . When all the electrons and protons were created their expanding electric fields created space at C.