Talk:Principle of relativity/Archive 1

Archive 1

Proposal for new article

I'd like to propose a new article. first I copy the current article here, then I replace it with the article I wrote, so you can use the history to compare the content. I appreciate your comments. Cleon Teunissen 16:21, 27 Jan 2005 (UTC)

Galilean relativity

Historically, the first principle of relativity that was formulated was a principle of relativity of magnitude and direction of uniform motion suggested by the observation that there didn't seem to be a phenomenon in dynamics that will allow an observer to establish a zero point of velocity, nor a preferred direction.

Every choice of a zero point of motion, a choice necessary in order to perform a calculation, constitutes a choice of reference frame. All reference frames that move with respect to each other with uniform velocity are called inertial reference frames. The circularity of this definition is inescapable, since there is no preferred inertial reference frame

In Galilean relativity, reference frames are related to each other in a intuitive way: to transform the velocity of an object from one frame to another, the vector representing the velocity of the object is added to the vector representing the velocity difference between the two reference frames. Such a transformation is called a Galilean transformation. The geometry of space is assumed to be Euclidian, and the measurement of time is assumed to be the same for all observers.

Some laws of motion are valid indepent of reference frame. For example: in all inertial reference frames, the common center of mass of a group of particles moves in uniform motion. The independency of reference frame suggests that that law of motion is fundamental, more so than other laws.

Accelerated motion

When accelerated motion is involved, there are phenomena that will allow an observer to establish a zero point, there are phenomena that determine a preferred reference frame. It is possible to measure angular velocity inside a room that is cut off from all information, other than the fact that the room occupies space. Navigational gyroscopes inside a ship can detect the rotation of the earth and the direction of the rotation of the earth, allowing ships to know the geographic North without a magnetic compass. See also the external links of this Gravity probe B, and the Sagnac effect.

A frame with zero acceleration is not a zero point of motion. Rather, the zero point of acceleration is related to all inertial reference frames simultaneously, as if all inertial reference frames are in fact a single all-in-one state.

In performing calculations it is possible to transform from a rotating frame of reference to an inertial frame of reference and vice versa. As with all transformations in Euclidian space the vectors are added, but in the case of a rotating frame of reference the acceleration vector is a function of time and/or spatial coordinates.

Special relativity

Einstein saw, as did his contemporaries, that if one assumes that both the Maxwell equations are valid, and that Galilean transformation is the appropriate transformation, then it should be possible to measure velocity absolutely. Einstein showed that if one assumes that the Lorentz transformations are the appropriate transformations for transforming between inertial reference frames, then that constitutes a principle of relativity that is compatible with the Maxwell equations.

The assumption that the Lorentz transformations are the appropriate transformations has vast implications. The intuitive assumption that time is universal has to be relinquished.

General relativity

Since space is not Euclidian the existing transformations between an inertial reference frame and an accelerating reference frame were clearly not appropriate.

Einstein formulated a new theory, unifying the description of the geometry of space-time and the description of the interaction of mass and the geometry of space-time, achieving two goals at once: a theory of gravity in which the mediator of gravity propagates at lightspeed, and the geometric means to perform in calculation a transformation between any two reference frames, inertial of non-inertial.

Being able to calculate a transformation doesn't in itself imply nature works that way. Before and after the introduction of General relativity, angular velocity was measured with devices that make a local measurement. The background reference frame of these sensors is space-time itself. Currently, mechanical gyroscopes onboard the satellite Gravity probe B are used to measure a rotation of space-time itself, space-time close to Earth that rotates with respect to the universe, due to the rotation of planet Earth nearby. If general relativity is correct then the gyroscopes should, over the course of a year, deviate 42 milliarc-seconds due to frame dragging.

External links:

• Gravity probe B experiment to measure frame dragging
• Reflections on Relativity, section 2.7 The Sagnac effect
• Ring interferometry experiment. University of Canterbury, New Zealand

The POR Description is fundamentally wrong

The fundamental introduction is, essentially, wrong. It confuses principles of mathematical form with principles of physics. The POR is a *physical* principle not a mathematical principle. Unfortunately, the literature consistently conflates “physical laws of physics” with “mathematical equations of physics”. The POR refers to the actual physical behaviour of real physical objects. It is assumed to be valid even if the equations themselves describing the behaviour didn’t exist. “Laws of physics” refers to actual physical behaviour, not the equations. Unfortunately Einstein was confused on “The Principle of Covariance” and the POR, and this confusion has fuelled the misunderstanding, despite it well accepted after the fact that Einstein was mistaken on this point. It’s a mathematically fact that all theories of physics may be written “Covariantly”, that is, independent of coordinate system, irrespective of whether the physical system itself behaves independently of motion. Thus the current lead in description of "the laws of physics have the same form..." says, essentially, nothing physically. The bit about "...admissible frames of reference…" is equally meaningless as “admissible” is not even defined.

It is my view that the introduction should be replaced with something along the lines of the below. The idea being to state what the POR really is, and how it is commonly misrepresented. I will leave this here to gauge response from other editors. Kevin aylward (talk) 09:37, 17 October 2020 (UTC)

In Physics, the Principle Of Relativity (POR) is the principle that the laws of physics are independent of uniform (inertial) motion. That is, the physical relations between objects are not effected by any joint motion of those objects.

The principle is a real physical principle, relating to real physical processes. However, it should be noted that the POR is often incorrectly stated by way of reference to general properties of mathematics and mathematical forms, which may also be true even if the POR itself was false. It should also be noted that the POR is often misunderstood with regard to reference frames and coordinate systems. Physical processes are inherently independent of coordinate systems because coordinate systems are mathematically only labelling constructions designed to be so independent. However, there is no a prior reason why physical processes should be independent of inertial reference frames. The POR expresses this last point Kevin aylward (talk) 09:37, 17 October 2020 (UTC)

Untitled

I have replaced the existing article with a new article. I wanted to emphasize how special relativity restored relativity in physics. I also wanted to emphasive that observation is the basis of physics.

There is a widespread misconception that general relativity extends the concept of relativity to accelerated motion. Einstein certainly hoped to achieve that, and at first he believed that general relativity had achieved that, but after correspondences with the astronomer Willem de Sitter, and the mathematicians Herman Weyl and Felix Klein, Einstein agreed that it is unclear whether the theory of general relativity does imply Mach's principle, contrary to what Einstein had hoped.
In later years, Einstein formulated the principle of equivalence in a more restricted form than at first.
External link to 146 Kb PDF document: The Einstein-De Sitter debate
--Cleon Teunissen 19:21, 25 Feb 2005 (UTC)

THREE principles

Two were stated as essential by Einstein, " These two postulates suffice for the attainment of a simple and consistent theory " reference

http://www.fourmilab.ch/etexts/einstein/specrel/www/

and then he added his personal POV which is "we establish by definition that the ``time required by light to travel from A to B equals the ``time it requires to travel from B to A." which is the basis of his derivation of the cuckoo transformations. (same reference). Claims of one principle only are WP:NPOV violations and WP:OR violations, the average reader should not be mislead. Der alte Hexenmeister 23:34, 11 July 2006 (UTC)

Mass-energy versus Gravity

Within the section on General Relativity, you state the following:

"Gravity alters the rate of progression of time" and "The deformation of space-time due to gravity ..."

IMHO, 'Gravity' in the above statements should be replaced with 'mass-energy'. In other words, gravity IS deformation of spacetime due to mass-energy. Alfred Centauri 12:26, 2 May 2005 (UTC)

I think you have a good point there. I've done some editing.

Besides that, I'm not sure whether an article on the principle of relativity should mention the theory of general relativity at all. The principle of relativity refers to the principle of relativity of inertial motion. the discussion of GR in the article is so brief that I wonder whether it is doing any good. --Cleon Teunissen | Talk 16:34, 2 May 2005 (UTC)

Principle of Relativity: range of applicability

I think that the statement that

 "The principle of relativity refers to the principle of relativity of inertial motion."

is an interpretation or a judgement, rather than a definition.

Literally, the principle of relativity is the principle that things are, well, relative. How far that principle can be legitimately be applied (and to what things) is a question that has occupied physicists for centuries.

In Principia, Isaac Newton outlined a model in which inertial motion was relative and "accelerated" or "rotational" motion was not. But a powerful contemporary, Bishop Berkeley, objected on the grounds that Newton's model applied the principle of relativity insufficently broadly. According to Berkeley, the inclusion of arbitrary absolute properties weakened the theory - to Berkeley, there should be no absolutes but God. Although he phrased it in religious terms, his objection was basically the Occam's Razor argument against the inclusion of unnecessary entities, making everything relative produces a more self-contained model.

Newton seems to have been aware of the problem and in an odd passage in Principia, seems to talk about the ability of revolving shells of matter to make enclosed objects partake of their revolution. This sounds very much like an early description of the principle of relativity applied to rotation, and would nowadays be described as a Machian idea, or perhaps as a description of frame-dragging under general relativity. It's difficult to see how this fits with the rest of Principia, so perhaps Newton included the section to pacify Berkeley.

Ernst Mach was a high-profile proponent of the principle of relativity in its most general physical sense, and strongly influenced Einstein. According to Mach, "relativistic" physics meant fully relativistic physics, in which acceleration and rotational effects were due to the interplay of an object with background environmental matter. Without that background reference, acceleration or rotation would not be physical, and if there was no physical cause, there should be no physical effect. If we claimed that the entire universe was rotating, there should be no resulting forces, because there would be nothing physical for the rotation to exist relative to, and the supposed rotation would be a purely mathematical notion with no physical consequences. In his book "Science and Mechanics", Mach explicitly defines a "relativist" as being someone who subscribes to this much more general principle of relativity. When Einstein produced his "special" or "restricted" theory of relativity (aka "Special Relativity" or "SR"), Mach reputedly did not like it at all -- by his standards, it was probably not worthy to be referred to as theory of relativity, although Mach himself did not seem to have anything more constructive to offer.

Einstein then went on to produce his "General Theory of Relativity", which was intended to at last be a fully compliant Machian theory, and to begin with, descriptions of "General Relativity", or "GR" did assume that the theory was a fully successful implementation of the general principle of relativity (see e.g. the content of Einstein's 1921 Princeton lectures, reprinted in "The Meaning of Relativity"). In later years this claimed compliance had to be downgraded somewhat, the theory had allegedly been found to allow rotating-universe solutions, and the fact that Einstein had designed it to reduce to SR meant that certain non-Machian assumptions built into SR were inherited, at least in part, by the general theory. A paper by the Harwell research group described an experiment where they had successfully measured time dilation in centrifuged material, and the paper set the cat amongst the pigeons by mentioning that the same basic result could be predicted either by applying the principle of equivalence and calculating the effect as gravitational time dilation, or by applying special relativity and calculating the effect as the result of velocity-based time-dilation. Unfortunately, although both calcualtions were adequate to explain the result, they were found to be geometrically incompatible, so at least one had to be wrong, and since invalidating SR would also invalidate the current version of the general theory, it was decided that the least worst option was to retain SR and restrict the accepted domain of validity of the equivalence principle only to situations where it did not conflict with accepted SR work. Where Einstein had originally said that acceleration and gravitational effects were wholly equivalent and interchangeable, later writers preferred to say that this had only been an approximate relationship rather than a law, that Einstein hadn't meant it literally, and that of course, one could in practice distinguish between acceleration and gravity.

Towards the end of his life, writing in Scientific American (April 1950), Einstein wrote that he no longer believed that it was correct to use the special theory as a foundation or building block for more advanced gravitational theory. A fully general theory, he said, ought in his opinion to be designed to conform to the general principle from the ground up without these sorts of compromises. Unfortunately he died without being able to produce a third, all-encompassing theory of relativity, and to this day, the true status of Mach's Principle (or, the idea that the general principle of relativity should be truly general) still generates controversy.

--ErkDemon 03:21, 24 Jun 2005 (UTC)

Pinciple of relativity: range of applicability (2)

A physicist has no choice but to follow where the evidence leads him. We are faced with several layers of counterintuitiveness.

We have that there is, as far as we can tell from measurements, unconditional relativity of position in space. We have unconditional relativity of the first derivative of place: relativity of inertial motion in space. We do not have relativity of the second derivative of position in space: acceleration is locally detectable; it is possible to measure acceleration with respect to local space. (Generally speaking, all motion is motion in space-time, of course)

I should explain why I use the distinction between global measurement and local measurement.
An observer in a space-craft, moving inertially in space, can take measurement readings of the Cosmic Microwave Background Radiation, and thus he can infer his own velocity with respect to CMB. But that measurement is looking at someting that originated a very long time ago, very far away. If you apply the restriction that you are not allowed to look very far, then the finding is that what is detectable is relative velocity. It appears to an observer that only relative velocity can be used in any theory of physics.

Remarkably, acceleration with respect to the local inertial frame of reference is detectable, any accelerometer will tell you how hard you are accelerating with respect to the local inertial frame of reference. (I follow the convention of defining an 'inertial frame of reference' as follows: a coordinate system that is co-moving with a free-falling test mass.)

The relativistic theory of gravitation describes that space-time is not a fixed background. As John Wheeler put it ultra-condensed: "Matter/energy is telling space-time how to curve, space-time curvature is telling matter how to move."

Gravitational curvature of space-time meant that physicists had to retreat from the position of special relativity. The Minkowski space-time of special relativity is quite different from newtonian absolute space, of course, but a form of absoluteness is still present: any inertial frame of reference extends to infinity. Minkowski space-time is not a Euclidian space, but it shares with Euclidian space that it is a geometrically straight space.
Gravitationally curved space-time has the property that inertial frames of reference at different locations can (depending on the circumstances) be accelerating with respect to each other.

So in our solar system we are surrounded with examples of local inertial frames of reference that are accelerating with respect to each other. The Earth, in its orbit around the Sun, is following a geodesic, so the frame of reference that is co-moving with the center of mass of the Earth is a local inertial frame of reference. A satellite, say a space station, orbits its own primary, the space station is orbiting Earth. Etc. etc.

Interestingly, there are very few examples of local inertial frames that are rotating with respect to each other. General relativity does predict the phenomenon of frame dragging but it is an exceedingly small effect, only significant in the vicinity of very very heavy, very rapidly spinning celestial bodies, such is rapidly spinning neutron starts.

Rotation is absolute

Rotation is absolute, but not in the sense that Newton described.
The difference between velocity and rotation is that while you cannot measure your own velocity with respect to space itself, you can measure your own rotation with respect to your local space. (As noted, frame dragging implies the possibility of local rotational motion of space-time, but frame dragging is exceedingly insignificant.)

It is possible that Newton reasoned as follows: "If I assume that acceleration is absolute, and it appears that observation compels me to make that assumption, then there must be an underlying reference. If the second derivative of position, acceleration, has a reference, then so must the first derivative: velocity, even while it remains hidden from view.

Others have argued: if velocity is relative, then there can be no background reference at all, implying that acceleration cannot possibly be absolute. Then the task for the physicist is to find a theory that explains why acceleration appears to be absolute, while being relative all along.

It seems to me that Nature is even more counterintuitive than anybody expected.
To my knowledge, physicists have, for the time being, come to the conclusion that position and velocity are unconditionally relative, but that acceleration/rotation is absolute.

Hmm, it seems to me that most physicists don't really try to understand Nature but instead positivistically interpret the laws of motion as if they describe not observations but reality itself... (but then, how many physicists are skilled in philosophy?) Harald88 21:28, 29 October 2005 (UTC)

As far as I know, Einstein attempted to implement what he coined as Mach's principle.
What if a theory can be formulated in which there is full reciprocity of rotational transformations? If you have a hollow spherical shell of solar system size that is rotating, will that result in frame dragging effects that result in the inside of the rotating sphere in a space-time deformation that exactly matches the physics of rotation? That is: if inside the hollow spherical rotating shell a planet resides, will observers on that planet be able to figure out whether the planet they are on is rotating, or that some hollow sphere is rotating around them. To my knowledge the general theory of relativity does not satisfy this form of Mach's principle, you can tell the difference, by way of measurement. Hence the assertion: velocity is relative, acceleration/rotation is absolute.

What we see in our universe is relativity of inertial motion. As far as we can tell with our present state of knowledge, Nature has not seen fit to also have the property of relativity of all motion, including accelerational/rotational motion.

Well, look at it this way. If nature would have fitted in the property of relativity of all motion then the universe would not be coherent, that is, united as or forming a whole. Hansholler (talk) 07:17, 4 August 2011 (UTC)

Inertia

So what can inertia be? If space is a physical entity, putting up resistance against acceleration, how then can velocity be without any resistance?

Interestingly, there is a physical parallel between inertia and the phenomenon of inductance. Imagine a current circuit with in it a self-inducting coil. Let the current curcuit be superconducting. This superconducting current circuit will have zero resistance to current. However, when an electric potential is applied to change the current strength, then the change in current strenght elicits induction in the coil and that elicits a counterforce that opposes that change in current strenght.

That does not explain inertia, it just provides an example of a system that offers zero resistance to the first derivative, but that does put up resistance against the second derivative: change of current strenght is opposed.
--Cleon Teunissen | Talk 11:16, 24 Jun 2005 (UTC)

Actually, it partially explains inertia: for the selfinduction of an accelerating electron corresponds to its relativistic inertia increase. You can't regard these two things seperately for then you'd have to add the effects, and that would be erroneous. And funny enough, one century ago this was all well understood, and my 25 year old textbook explains how the electron's magnetic field corresponds to the increase of "relativistic mass" (which is currently out of fashion, and with that also that insight). Harald88 21:39, 29 October 2005 (UTC)

Principle of relativity: range of applicability (3)

I think that the statement that

"The principle of relativity refers to the principle of relativity of inertial motion."

is an interpretation or a judgement, rather than a definition. Literally, the principle of relativity is the principle that things are, well, relative. How far that principle can be legitimately be applied (and to what things) is a question that has occupied physicists for centuries. --ErkDemon 03:21, 24 Jun 2005 (UTC)

You made a valid point: I suppose the following formulation could have been used:

"The current principle of relativity as used in physics entails a principle of relativity of inertial motion."

Here is how I use the expression 'principle of relativity':
The content that the scientific community attributes to the 'principle of relativity' changes over time. In that sense there is a succession of principles of relativity, starting with the proposal of Galileo Galilei. Invariably the Principle of relativity and the physics of kinematics are completely intertwined. I find it hard to separate them conceptually.

The newtonian principle of relativity involves the following two assertions:
(G1) When two observers are moving inertially with respect to each other, and they are watching the same events, then they will percieve the distances, velocities etc differently, but in the end they will infer from their observations the same body of laws of kinematics. (That is pretty amazing, but that is the way it is.)

(G2) When you want to transform measurements taken as seen from one inertial frame to another frame you perform vector additions; velocity addition is always straighforward vector addition.

(The G's in (G1) and (G2) stand for Galilei, for newtonian relativity is by convention called Galilean relativity.)

Interestingly, (G1) does not need to be altered in any way for special relativity, it is exclusively (G2), the assertion about how to transform measurement data from one inertial frame to another that was modified in the transition from Newtonian kinematics to special relativity.

So if there is such a thing as the principle of relativity, I would say (G1)
--Cleon Teunissen | Talk 14:17, 24 Jun 2005 (UTC)

Theory of relativity

Why are we including the theory of relativity on this page? I may cause confusion to the reader.--Light current 20:25, 20 January 2006 (UTC)

Why not? The special theory of relativity is based on the principle of relativity; the general theory was an extension of it (but that extension failed). The text on GRT desperately needs rephrasing, that's for sure; nearly everything about gravitation should be removed, it's not relevant and indeed confusing. Harald88 22:19, 20 January 2006 (UTC)

• It will confuse people.
• We have a pages dedicated to the special and general theory of relativity
• Principle of relativity does not depend on relativity

Lets keep thing as simple as possible please!--Light current 22:24, 20 January 2006 (UTC)

It is essential to distinguish Einstein's general principle of relativity from the standard PoR, which he later called the special principle of relativity, exactly to reduce existing confusion even among scientists. See also the first discussion by Cleonis on this page. Of course, if you find a way to make this disambugation more transparent, that would be good. Harald88 12:21, 22 January 2006 (UTC)

Indian Relativity

I remoeved a staement about an 'Ancient Indian theory of relativity' I doubt that any 'ancient Indian theory' proposed exactly what is meant here by principle of relativity. If we could find out what that word meant, then we could add it as a footnote to the article. DJ Clayworth 19:57, 2 February 2006 (UTC)

And I removed it again. The link provided by the author (namely, http://www.crystalinks.com/indiascience.html) does not say anything substantial at all about "Indian Relativity". If you do not know what exactly this 'Indian relativity theory' stated then how can you deduce that it is relevant to the topic of our article? The article is about physics, no need to quote here every ancient sage who used the word 'relative' once or twice in his writings.

—Preceding unsigned comment added by 212.199.22.14 (talk • contribs)

See also Gravitation for a similar discussion of a dubious invented in India claim. See these claims regarding alleged ancient Indian helicopters and such like, which rather speaks for itself.---CH 03:19, 21 April 2006 (UTC)

This page needs a rewrite

Please note that the principle of relativity is not the theory of relativity. As-is, this page could be a redirect to theory of relativity. Instead it should have sections entitled "special principle of relativity" and "general principle of relativity", and talk about what those are. Kindly note that the special principle is Galileo's original principle of relativity. Talk of electromagnetism and the speed of light should be kept to a minimum, and at best be part of a quick reference to special relativity.

The question to be answered here is "what is the principle of relativity?". Instead, this is a discussion of the theory of relativity. That needs to be corrected. --EMS | Talk 16:09, 11 July 2006 (UTC)

No, it is a discussion of how the theories of relativity derive from the principle of relativity, as defined in the opening sentence as:

The principle of relativity, refers to Galilean relativity and its subsequent application to Albert Einstein's special relativity and general relativity.

You seem to wish for the principle of relativity page to eschew all 20th century developments. Such a page would then be called Galilean relativity - and it already exists. It is the theory of relativity that needs a rewrite or new title -- the title is singular but the content is plural. --Michael C. Price ^talk 16:34, 11 July 2006 (UTC)

You are confusing the principle and the theory. You need to get the principles stright, and then do please mention their connections to the theories. However, you do not need to talk about the theories themselves. I do see the theory of relativity page needing some expansion, but only to list major consequences. This page needs to be refocussed of Galileo's principle and Einstein's generalization of it for general relativity. --EMS | Talk 17:08, 11 July 2006 (UTC)

Our viewpoint and motivation seem identical, we are just disagreeing over the means. I see the need to distinguish between the principle and the theories, and for the principle to focus on Galileo; this page needs to split the Galilean section in two (which I'll attend to). But there is a natural overlap between the theories of R (pl) and the principle of R (sing), since all the theories have the same principle in common. However theory of relativity (sing) should just disambiguate onto single theory and not talk about the relationship between theories. I am still unhappy with the duplication between the two pages as they stand; it will lead to endless rewrite confusion. --Michael C. Price ^talk 17:33, 11 July 2006 (UTC)

I wholeheartedly agree with your concern about duplication. My point is that the theory of relativity page does what I want it to do, and there is no need for this page to duplicate that. This page needs to focus more closely to the principles. i. e. -

• The speical principle of relativity - The laws of physics are the same for any set of observers in uniform linear motion with respect to each other.
• The general principle of relativity - The laws of physics are the same for all observers independent of their state of motion.

This article does not even state the general principle. Instead of a discussion of the theories of relativity, what is needed here is a discussion of the principle and their relationship to the theories. Once you focus in, you will find that you are looking at the foundations of relativity, and are paying much less attention to what has been built on that foundation. --EMS | Talk 04:31, 12 July 2006 (UTC)

Actually the way you have stated the general principle is confused, since the general principle is more than just general covariance. This article states that GR exhibits a local Lorentz covariance, which is a stronger statement than just general covariance since it implies general covariance (all observers see same physics) and that the local physics they see is that of SR (i.e. Lorentzian). This muddleness extends through a number of GR article. --Michael C. Price ^talk 09:58, 12 July 2006 (UTC)

erroneous statement about Maxwell's equations

Some anon removed "since the invariance of the speed of light is a consequence of Maxwell's equations of [[electromagnetism]".

It is doubtful that any quality publication claims that Maxwell's equations alone suffice.

Maxwell himself used his equations and publicly disagreed with that claim by proposing the MMX (his equations were defined relative to the ether). Maxwell's equations together with the PoR do have that consequence however. It may also be derived form combining his equations with the electromagnetic theory of matter. Harald88 21:09, 9 October 2006 (UTC)

I have restored the claim, adding the PoR requirement, which makes the statement correct. It also means that it leads naturally onto the next paragraph. --Michael C. Price ^talk 23:46, 9 October 2006 (UTC)

Fine to me Harald88 19:04, 10 October 2006 (UTC)

Berkeley's General Relativity

What about the general assertion that underlies all relativity? This is equivalent to Berkeley's Idealism. It is the statement that all objects exist as they are only in relation to an observing subject. No object exists as it is in itself, apart from an observing subject.Lestrade 18:02, 8 November 2006 (UTC)Lestrade

General principle of relativity

The general principle of relativity states that physical laws should be the same in all reference frames -- inertial or non-inertial. An accelerated charged particle might emit synchrotron radiation, though a particle at rest doesn't. If we consider now the same accelerated charged particle in it's non-inertial rest frame, it emits radiation at rest.

Indeed physical laws are clearly not the same in non-inertial reference frames. As an example Newton's laws of motion are not valid in non-inertial reference frames. Therefore, we can decide, whether the Earth is rotating or not as demonstrated by the Foucault pendulum. I conclude, general relativity is proven to be ridiculous or The Emperor's New Clothes. 84.59.51.81 08:42, 5 April 2007 (UTC)

Please see Wikipedia:Talk_page_guidelines and in particular "Talk pages are not a forum for editors to argue their own different points of view about controversial issues". Alfred Centauri 12:48, 5 April 2007 (UTC)

Serious Blunder and Omission In Special Relativity Section--Failure to mention Poincare

The special relativity section fails to attribute to Poincare the credit for formulating the principle of relativity. The article also attributes to Plank the credit for this, but is unclear. Poincare was first to use the term principle of relativity not Einstein or Plank. Other historical facts are garbled and confusing. No credit given to Lorentz for theorem of corresponding states as predecesor of Einstein's version of the principle. Historical information needs rewrite.71.251.178.128 16:23, 26 July 2007 (UTC)

Here are my suggestions, anonymous:

(1) Sign up for an account so I don't have to call you anonymous

(2) Be bold, and make the corrective edits you believe are necessary - make sure to include authoritative references, please!

(3) Important: Make sure to read and absorb the following warning which is printed below the edit box:

If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it.

(4) Also Important: Make sure to read and absorb this: Wikipedia is not a soapbox

Regards, Alfred Centauri 23:32, 26 July 2007 (UTC)

The article says, "Einstein... discarded the notion of absolute time." and mentions 1905. Poincare said in 1898, "There is no absolute time." —Preceding unsigned comment added by 81.149.223.218 (talk) 14:24, August 25, 2007 (UTC)

Indeed, Poincare was the first one to formulate the modern PoR on record (that is, for all laws of nature). He should be cited. Harald88 08:36, 30 October 2007 (UTC)

erroneous statement

A statement to correct (if not soon corrected, I'll remove it):

Nonsense:

"Many physicists, including both Larmor and Lorentz, discarded the special principle of relativity in favor of a luminiferous aether -- a plenum that fills space and is a medium for electromagnetic radiation."

Fact: Lorentz tried to develop a theory that obeyed the PoR and achieved it (almost) in 1904. See also the book "The Principle of Relativity" by Einstein and Lorentz. I cite Lorentz: "Poincare has objected to the existing theory of electric and optical phenomena in moving bodies [...] It would be more satisfactory if it were possible to show by means of certain fundamental assumptions and without neglecting terms of one order of magnitude or another, that many electromagnetic actions are entirely independent of the motion of the system. Some years ago, I already sought to frame a theory of this kind"

Harald88 08:46, 30 October 2007 (UTC)

OK I now guess what may have been meant, and I'll correct it accordingly. Harald88 17:58, 4 November 2007 (UTC)

History.

Uh. I think the history section might need to be, you know, rewritten? It only reads: Aristotle Newton Einstein Dbutler1986 (talk) 01:56, 16 February 2008 (UTC)

Agreed. This makes no sense whatsoever. Borg Sphere (talk) 17:06, 28 February 2008 (UTC)

About new ideas

Relativity principle is a general topic. New ideas shoud be allowed to be incorporated here. Otherwise, here will be a dead field without any updates. Kylin.Ma (talk) 01:16, 13 June 2009 (UTC)

New ideas are fine, but your self-promotion is not. Irrelevant promotional material removed from article. Vsmith (talk) 01:36, 13 June 2009 (UTC)

I agree with you about the avoidance of self-promotion. So could you help me with that rather than I do it by myself? Thanks. Kylin.Ma (talk) 01:49, 13 June 2009 (UTC)

If your work is published by a reliable source then you should provide that reference here for others working on this article to consider and possibly use. Your current approach of adding a new section here and to Simulated reality referenced to your own work is not acceptable. Please read conflict of interest. Vsmith (talk) 02:02, 13 June 2009 (UTC)

Thanks. You are right. This article was written in 2005 and has been put into public domain 3 years ago. So in some sense, it's no longer something quite new. And it's also closely related to this topic. That's why a section is summarized here. Please think about its relevance and give your fair opinions. Thanks. Kylin.Ma (talk) 02:16, 13 June 2009 (UTC)

Quoting from the purpose page of the "verifiable source":

"'The original and continued purpose of these pages is to present an assessment of special relativity. This purpose has since been expanded to include all aspects of science and philosophy. Readers who have opinions on the subjects are encouraged to participate. Please make use of the GSJ forum for any dialogues that may serve to highlight and explore the subjects covered on-site for the benefit of correspondents and other readers."

This alone defines it as a highly unreliable source, also known as a soapbox. So the article is irrelevant. DVdm (talk) 13:11, 13 June 2009 (UTC)

Incorrect expression of general principle of relativity

The general principle of relativity states that "local laws of physics are the same in all coordinate systems". The current article is incorrect, because it does not state local laws, and because it confuses coordinate systems with reference frames. A reference frame is not a coordinate system. It is the physical matter from which a coordinate system may be empirically defined. —Preceding unsigned comment added by RQG (talk • contribs) 10:37, 1 April 2010 (UTC)

No mention of the Cosmic Microwave Background CMB

The article could use a section on the cosmic microwave background radiation. —Preceding unsigned comment added by NOrbeck (talk • contribs) 07:50, 25 July 2010 (UTC)

order of the timeline

Why is the time line out of order? Hansholler (talk) 07:26, 26 July 2011 (UTC)

Assumption

The article speaks of Newton's using an assumption of absolute time. The article on Absolute time says Newton flatly stated that absolute time existed. — Preceding unsigned comment added by 216.104.121.229 (talk) 12:23, 19 March 2014 (UTC)

not written for a general audience

can anyone tell me with a straight face that this is written for a general audience ? this is not General relativity was developed by Einstein in the years 1907 - 1915. General relativity postulates that the global Lorentz covariance of special relativity becomes a local Lorentz covariance in the presence of matter. The presence of matter "curves" spacetime, and this curvature affects the path of free particles (and even the path of light). General relativity uses the mathematics of differential geometry and tensors in order to describe gravitation as an effect of the geometry of spacetime. Einstein based this new theory on the general principle of relativity, and he named the theory after the underlying principle. — Preceding unsigned comment added by 2601:192:4701:BE80:8409:3056:A236:A59F (talk) 02:22, 31 May 2019 (UTC)

A very unclear (possibly, erroneous) statement

It would be helpful if the authors of this article could clarify the following statement regarding the relativity principle and the principle of the independence of the speed of light (in vacuum) from the motion of the source:

"These two principles were reconciled with each other (in Einstein's treatment, though not in Poincaré's) by a re-examination of the fundamental meanings of space and time intervals."

Why exactly are these principles not reconciled within Poincare's treatment?

I agree with this anonymous comment, and removed the parenthetical remark. Roger (talk) 06:36, 26 December 2021 (UTC)