User talk:Ems57fcva/archive 3

From Wikipedia, the free encyclopedia
Jump to: navigation, search

White holes ?[edit]

Hi EMS. I was wondering if you knew much about white holes. If so, and if you have the time, I welcome any contributions you may have about them in my sandbox article: User: Mpatel/sandbox/White hole. I want to make the article as clear as possible, as there is a lot of nonsense there at the moment. ---Mpatel (talk) 17:52, August 11, 2005 (UTC)

Thanks for the suggestions. ---Mpatel (talk) 08:44, August 12, 2005 (UTC)

Hi, M, as I was adding a note below, I saw your query---isn't a white hole just a time-reversed black hole? See MTW.
Actually, you and EMS can probably both help me with this next thing; see just below the line!---CH (talk) 00:06, 14 August 2005 (UTC)
Hi Chris. Yeah, the definition usually accepted by hardcore GR buffs is that white holes are time-reversed black holes. I want to write a decent article on white holes by unstubifying it and to accomplish this by discussing the definition and history of the concept, mentioning their effects, and of, course, the reason why many experts don't believe in them. Issues of energy conservation and violating the second law of thermodynamics should be included in there somewhere, as well as more exotic suggestions like relation to time-asymmetry and Penrose's idea that white holes cannot be accomodated in a TOE. If you have any other suggestions, they are most welcome. ----Mpatel (talk) 10:15, August 14, 2005 (UTC)

General theories of relativity[edit]

Hi, EMS and MP, can you look at the latest version of general theory of relativity? See the "Alernative theories" section and note that I just wrote another new article in the "Gravitation theories" section, on Nordström's theory of gravitation. Now compare General theories of relativity (sic), a new article created by a user "ErkDemon" and placed in the "Gravitation theories" category. I felt ErkDemon might be able to contribute to needed articles, but that this particular article is redudandant and misleading, so I flagged it and wrote a message on the talk page.---CH (talk) 00:06, 14 August 2005 (UTC)

new added word to GR article[edit]

hi, i was thinking of adding exactly the same word to exactly the same place in the GR article that you did, but on second thought, i thought maybe that restriction is not accurate. according to GR princples of equivalence, is not the astronaut who is being accelerated at 9.8 m/s^2 in space, is not the curvature in space-time he experiences the same curvature we do sitting on the surface of Earth? just curious. r b-j 22:42, 17 August 2005 (UTC)

thanks for the relpy, EMS. i think i got it. r b-j

Category:Science timelines (ordering of entries)[edit]

Hi there. I've gone through all the entries, and arranged their indices in a uniform and systematic fashion. I removed the cleancat template, and placed your original notice on the discussion page. Hope it was helpful :) ---Kieran 13:04, 22 August 2005 (UTC)

Ladder Paradox[edit]

Hello - If you have time, could you check out the Ladder paradox page, especially the discussion page. We are in dire need of a tie-breaker. Thanks PAR 02:22, 23 August 2005 (UTC)

EMS, what use is a "self-link" in an article???[edit]

it doesn't appear to have taken in General relativity anyway. but why one would do that is a curiousily to me. r b-j 23:58, 23 August 2005 (UTC)

GR stub ?[edit]

Hi EMS. I was wondering whether it would be a good idea to create a general relativity stub template. See CH (talk) for more info. ---Mpatel (talk) 10:18, August 27, 2005 (UTC)

Just created the {{relativity-stub}} (and attached it to, among other articles, energy conditions) and Grutness made the category Category:Relativity stubs. ---Mpatel (talk) 16:02, September 3, 2005 (UTC)

WikiProject GTR draft manifesto[edit]

Hi, just wanted to let you know that I have finally completed the first draft of the WikiProject GTR manifesto. I have also found out what I need to do to formalize the project (very easy, actually), but I will wait for more comments on the first draft, since it seems wise to have the project pages in good shape before publicizing it widely. Since ErkDemon has been contributing lately to the GTR pages, I am about to leave a message on his home page asking if he would like to sign up as a fourth charter member.---CH (talk) 02:51, 1 September 2005 (UTC)

GR rewrite ?[edit]

Hi EMS. There's been some recent chatter about making the general relativity article of featured status. I was thinking of having a shot at this. It'll also be a good form of temptation to maximise my (already reduced) time at WP. I'm going to create a sandbox version right now and advertise it on the general relativity talk page so that people can play around with that one. ---Mpatel (talk) 16:04, September 6, 2005 (UTC)

Go ahead and play with it. To bring this article up to feature article status, it needs to become more accessible and (if possible) breifer. The two items that I think need immediate attention are:
  1. The Relationship to other physical theories section.
    • The mathematical part is too arcane. This should be split off into a separate article and replaced with a verbally oriented section describing the associations in a manner more accessible to the general public.
    • The part on alternate theories is too large and detailed. This should also become a seperate article and be replaced with a much breifer writeup, focussed primarily on Brans-Dicke theory, Rosen bi-metric theory and Whitehead's theory.
  2. A subsection of the overview is needed describing the relationship between spacetimes/topologies, coordinate systems, and metrics, and their interaction with the Einstein field equations.
    • A major point is that the EFE apply to toplogies, but to numerically solve it one needs to impose a coordinate system and obtain a metric.
I do not see a need for a major rewrite here, but substantial work is still needed to make it a worthy feature article. So do feel free to have a crack at it. Once you have a draft Chris and I will certainly comment on it. --EMS | Talk 17:42, 6 September 2005 (UTC)
I may have misled you; I wasn't planning a major rewrite, just to tidy up the article to get it up to featured article status (FAS). ---Mpatel (talk) 17:49, September 6, 2005 (UTC)
Then we are on the same page. Go for it. --EMS | Talk 17:53, 6 September 2005 (UTC)

Geodesic Deviation[edit]

Sorry I got prolix again on Patel's sandbox discussion page. I oversimplified, however, some things about geodesic deviation. It provides of course a test for non-zero Riemann tensor. Also it could work in a torsional sense; you can see some of that in the pressureless-fluid example, but there the torsion is vorticity, while in general it could convert a parallel meridional ray bundle into a helical bundle - i.e. change paraxial or meridional to sagittal rays, in the sense of optics. If you aren't too familiar with optics, sagittal rays come into astigmatism and coma, but not into spherical aberration, curvature of field, or distorton. See [1]. Of course that's for optics, but in GR bundles of material particles follow paths that can be described similarly to ray bundles. The web citation I just gave does not mention sagittal rays but you can see [2] Also of course, geodesic deviation is what LIGO will measure. Pdn 04:43, 10 September 2005 (UTC)

GR with conservation of energy.[edit]

Jim -

This one is obscure enough that I need to see references for it. Otherwise I will remove it from the GR pages. (Note that someone else may choose to remove it, but it you can justify it I will defend it.) --EMS | Talk 02:53, 11 September 2005 (UTC)

EMS, thanks for prompt reply. I'm not sure however what refs you need to defend the page.
Obviously you don't need refs to conservation of energy since it's supposed to be the most fundamental law of physics. Neither you need refs proving that Einstein knew about this law and so he would have never created a theory contradicting it. Therefore his 1915 theory must have been a GR with conservation of energy. You might need refs to statements by gravity physicists saying that there is no conservation of energy in GR with expanding space in it (obviously not the same theory that Einstein proposed in 1915). But this one you must know if you doubt in reality of GR with conservation of energy.
If on the other hand you would like to see refs to those statements, I can provide them since I discussed the issue of conservation of energy in gravitation with many gravity physicists and the issue was even banned from sci.physics.research long time ago by Prof. John Baez as something that does not need to be discussed any loger since most of gravity physicists agreed already that energy isn't conserved in GR (however all of them meant not the original Einstein GR but one with Friedman metric and therefore Riemannian geometry of spacetime that contradicts the conservation). Prof. Baez even stated that It is always surprising when it happens, but sometimes to learn more about the world we must stop asking certain questions... ... namely, those based on false assumptions. An opinion that I don't share with Prof. Baez. Since I doubt that you don't know about details of structure of contrmporary GR I'm not sure what refs you need to defend the page.
By creating this page I wanted to turn attention of people interested in physics to the fact that presently we have a slightly different GR theory than the original Einstein's theory and the most prominent difference is the conservation of energy. It might be good also to turn attention of those people to the fact that the original Einstein's theory predicts most of those phenomena (maybe all) that are puzzling so much creators of the modified by addition of the expansion of the universe GR without conservation of energy. E.g. the original Einstein's theory surely predicts the "anomalous" acceleration of space probes (as noticed by many esearchers) and the illusion of accelerating expansion of space for the reason of "dynamical friction of photons" which is a delicate issue by itself. Since the dynamical friction (considered "negligible for photons" without proof by the contemporary gravity physicists) is an established physical fact you probably don't mean refs to this phenomenon. So what things you need the refs to in order to defend the page? I think that defending this page is worthwhile since returning to the original Einstein's GR (without the expansion of space) has a potential of solving many puzzles that otherwise need postulating new exotic entities not necessarily existing in the real world (e.g. "dark energy"). Jim 07:48, 11 September 2005 (UTC)

EMS, It suddenly occured to me that you might not object to conservation of energy (as I previously thought) but to my equations that I placed there that might look like deus-ex-machina stuff and so suggest that it's my original research rather than an obvious consequence of Einstein's original theory. Then the page just reqires editing to show that all of those things are in Einstein's oroginal theory, however not explicitly mentioned by Einstein and possibly considered by him obvious enough not to need any mentioning. If it is it then I'm going to rewrite the page to the form without any deus-ex-machina stuff in it. I hope it won't look like an original research because I'm not even trying to suggest that I discovered Einstein's gravitation. I'd like just to show how it implies the equations that I put on that page. Which is just a few steps of a high school math. Jim 08:36, 11 September 2005 (UTC)

Science pearls[edit]


Since you contributed in the past to the publications’ lists, I thought that you might be interested in this new project. I’ll be glad if you will continue contributing. Thanks,APH 11:33, 11 September 2005 (UTC)

Geodesic Deviation[edit]

I am still puzzling what the heck you think geodesic deviation has to do with the apparent Newtonian acceleration of dropped objects descending to earth. It made no sense at all to me when I first replied on the talk page for M Patel's sandbox, but I just got an idea. Possibly you are thinking that the Earth and the dropped object are both following geodesics around the Sun. But remember, please, that the equation of geodesic deviation is to be applied to test particles in a spacetime warped by massive sources. So you can't use it to explain the apparent attraction of the Earth for objects in its neighborhood. Of course, I agree that photons are affected, too, but since the spacelike and timelike components of their 4-velocity are equal, you do not get so dramatic effect, and so counter intuitive to Newtonian thinkers, as when you drop an object. In that case the time-component of the object's 4-velocity before dropping was huge (in fact, the space part was zero) and it is the bending of this velocity into the spatial domain that causes what we see as acceleration. If I have not guessed what you were thinking when you wrote "The operative phenomenon is called geodesic deviation, and it applies to light just as much as to a falling brick." I'd be curious. Thanks Pdn 19:39, 11 September 2005 (UTC)

more on geodesic deviation[edit]

I am sorry, EMS but you do not understand GR very well (I taught it for years and have published in it, as well as having been a contributor to the The Dictionary of Geophysics, Astrophysics, and Astronomy, Richard A. Matzner, editor (CRC Press, Boca Raton, 2001) ) . Your initials being the same as those of my old friend E. Myles Standish, who prepares the JPL ephemerides of the solar system, I had thought you might be he, but it can't be. You did not read where I pointed out that if you drop a rock from a cliff (or the Tower of Pisa) the important point is that such cliff or tower is NOT on a geodesic. That is the whole reason the rock drops. You cannot apply geodesic deviation to two objects one of which is on a geodesic and the other of which is not.

No. I am not that friend of yours in the least. As for the cliff not following a geodesic, that is true. However, if you limit geodesic deviation to neighboring positions all that it can account for is tidal effects. So I use the distant observer as the other observer in geodesic motion. Unklike the cliff, that observer is at rest with respect to the cliff because of its geodesic motion instead of the cliff's situation of being constantly accelerated.
If that impresses you as being overly subtle and legalistic, then we can fall back to the basic concept of geodesic motion in a curved spacetime. Do keep in mind that whatever way you want to describe it, this operates for all permitted states of motion, not just v << c. Also keep in mind that whatever the coordinate system that is being used, an observer in the spacetime can define temporal coordinates for himself against which all observable objects are moving forward with respect to. So even light is moving forward in time with respect to us (as well as also moving forward through space in a similar manner). So what I want for your remarks is two things:
  1. To be as general and all-inclusive as possible, and
  2. to be well integrated into the GR article.
--EMS | Talk 13:40, 12 September 2005 (UTC)

It is believed to be true (but very hard to prove, and to verify) that massive objects also travel on geodesics. That issue led to a whole series of papers by Nordtvedt and collaborators on the lunar orbit. See for example [3]

General relativity assumes that, and no experiments unambiguously refute it. In any case, the overall goal is to document GR here. --EMS | Talk 13:40, 12 September 2005 (UTC)

Your point about geodesic deviation would refer to the orbits of a bunch of fragments orbiting the Sun (similar discussion to what I gave about a rubble pile orbiting Earth.) It also most definitely refers to the tidal distortion experienced by a large, low strength object in free fall in the Earth's gravity, but Roche, Melosh and others handled that in a Newtonian model - it is hardly necessary or profitable to use GR in that case. Look on the Web for "Melosh" and "tidal breakup" if curious. I do not know what to do at this point if you are not ready to learn. Just ask yourself, please, what is the source of the Riemann tensor from which you would calculate geodesic deviation so explain a falling rock! If it is the Sun's, we are back to an orbiting body tidally breaking up due to the differential gravity of the Sun. If it is the Earth's, you are back to the undeniable fact that the cliff or tower edge is NOT following a geodesic! If it followed a geodesic it would fall with the dropped rock. It is supported by the solid earth (as explained on the same page) against being in geodesic motion. I don't insist you put this back in the article or allow me to do it (in a terser way), but if you do not understand the point you ought not to edit GR articles. Here is the quote which you apparently do not accept: ". So what people standing on the surface of the Earth perceive as the force of gravity is an inertial force created as a result of their undergoing a continuous physical acceleration caused by the mechanical resistance of the surface that they are standing on."

That is correct! I did not write it. It establishes that the surface of the Earth is not on a geodesic. As I say, there are items in the literature that attempt to show that the center of mass of the Earth orbits the Sun on a geodesic, and that the center of mass of the Moon (see Nordtvedt) follows a geodesic in the gravity field of the Earth and Sun, but nobody understanding relativity would say that points on the surface of the earth follow geodesics in the Earth's gravity field - the whole earth would in that case collapse to a black hole. In other words, if you insist on using geodesic deviation, you have to put the original support point (rim of tower or edge of cliff) on a geodesic too, which means removing the solid-earth support. Then you can examine whether the rock and the falling edge or rim converge or diverge (they converge, but very slowly), but you have abandoned the problem of why the person supported by solid earth sees the rock appear to accelerate. Pdn 05:00, 12 September 2005 (UTC)

The wording above is actually mine! So hopefully this makes the case that our disageement is more semantic than practical. Remember the distant observer! --EMS | Talk 13:40, 12 September 2005 (UTC)
P.S. One more thing: In addition to not requiring that the geodesically moving observers be neighboring, I also think at times in terms of deviation with respect to the coordinate system. Now coordinate lines are under no obligation to be geodesic paths: For instance the cliff is following a path that is parallel to the time axis, and which geodesic paths are constantly diverging (or deviating) from. Note that this is a visualization tool for myself -- The operative mechanism is the geodesic equations themselves. I doubt that you would disagree with the statement that the geodesic equations determine how objects what are not being acted on by a physical force move. --EMS | Talk 14:04, 12 September 2005 (UTC)

Neighboring points[edit]

The equation of geodesic deviation applies only to a first-order neighborhood. I challenge you to provide a reference that says it can be used for points distant from each other.

Worse, when you try to apply that equation, which has room for only one Riemann tensor, to points removed from each other, you do not know which value of the Riemann tensor to use - at point A or at point B.

It is poor practice to think of any of this in terms of coordinate system, since coordinates in GR are arbitrary. The only way one is able to attach a special meaning to a solution like the Schwarzshild one, which I assume you are using, is to assume invariance to rotation and to a timelike translation (technically to put the time coordinate along a timelike Killing vector.) That allows one to make easier correspondence with Newtonian theory, but that's about all, except that the coordinate system is rigid, which is also a help.

I am researching further the question of massive bodies. Pdn 19:34, 12 September 2005 (UTC)

OK. If you wish to restrict the term "geodesic deviation" that much, then so be it. Then treat what I have meant as being geodesic motion so that we can refer to such things as the falls of massive bodies as being inertial motion along timelike geodesics of spacetime.

Pdn's response[edit]

Dear EMS - thank you, by the way for dealing at such length with JimJast. I had several tries reading his magnum opus and it is too tiresome. About the massive bodies following geodesics I am still not sure I agree; I am familiar with the strong and weak equivalence principles but reserve the right to look further into the application to massive bodies. Sorry, but I hope to agree/disagree in a few days! Pdn 05:01, 13 September 2005 (UTC)

Now, I am not in the least restricting the term "geodesic deviation" - it's defined in terms of the Riemann tensor along one (1) geodesic, and it tells you how the neighboring ones are related; there's no way to go beyond that. If you want to extend the concept over a large distance then the burden is on you to say what value of the Riemann tensor to use, or you might want some kind of line integral of it - it would be a big research project. Pdn 05:01, 13 September 2005 (UTC)

As for your statement:

The only way one is able to attach a special meaning to a solution like the Schwarzshild one, which I assume you are using, is to assume invariance to rotation and to a timelike translation (technically to put the time coordinate along a timelike Killing vector.),
I'm not sure what the point is here. The Schwarzschild solution has those attributes inately, but you can impose any coordinate system that you like on a Schwarzschild spacetime and get geodesic equations that describe the same motion as unser any the geodesic equations for any other coordinate system. About the only thing special about the Schwarzschild solution is the simplicity of the representation of the metric. I also am not certain what the issue with massive bodies is. In GR, they follow timelike geodesics of spacetime, and nothing more needs to be said about it. See the Equivalence principle article for more of a discussion about this. --EMS | Talk 20:04, 12 September 2005 (UTC)

The point is that you wrote: " In one sense, the geodesic equations are descriptions of how an object's path deviates from the coordinate system as a function of time." I was just pointing out, as you seem to agree, that coordinates in GR are arbitrary. Thus, according to what set of coordinates you pick, you could get different answers for the deviation of a geodesic from a coordinate line. In fact, Kruskal-Szekeres coordinates eliminate the false Schwarzschild "singularity" (trapped serface) as a singularity, and if you used these coordinates, deviation from a coordinate line would be entirely different.Pdn 05:01, 13 September 2005 (UTC)

I certainly agree on the arbitrariness of coordinate lines. To some extent the use of the term "geodesic deviation" with respect to them is a tool in my own mind for dealing with the phenomenon. I can understand that this may not be the right semantics but I needed some "container" for the concept. In any case, you are quite correct that the geodesic equations for the Kruskal-Szerkes solution look very different from those of the Schwarzschild solution even though they are describing the same thing.
As for massive object traveling along geodesics of spacetime: Just think of the strong equivalence principle. Also, you're welcome on JimJast, but I think the time is coming for me to stop it. I doubt that he cares to listen, but occasionally someone like him does suddenly "get it". --EMS | Talk 05:17, 13 September 2005 (UTC)

I looked at the Wiki entry for strong equivalence principle and it reads: "The gravitational motion of a small test body depends only on its initial position in spacetime and velocity, and not on its constitution." Notice that it is a test body. I e-mailed Richard Matzner a day ago asking him a few questions relating to your items on geodesic deviation and massive bodies. If no reply, soon I may try Charlie Misner or Clifford Will. Of course, these guys are busy with real research and may not want to spend time on wiki issues. Assuming that the Nordtvedt theory and lunar lasing measurements severely limit the scalar-tensor (Brans-Dicke) theory (which yields non-geodesic motion for the Moon), the remaining issues I see are: (1) The definition of the center of mass of a massive body is not clear. It depends on if you use rest-mass, rest-mass minus binding energy of that mass, etc. Even that binding energy depends on your assuming a scalar potential, which is a post-Newtonian approximation. Problem may be there for a black hole, too. (2) I am concerned if the result (geodesic motion) would hold, for example, for orbiting binary neutron stars or neutron star-black hole combinations, when gravitational radiation is emitted. It is like the radiation-reaction problem in electrodynamics but harder in GR. It gets into self-fields. Here I would ask Joan Centrella or, again, Charles Misner if I don't hear from Matzner. This is a research-level question and it does not affect Wikipedia unless I get a clear answer and, I suppose, you agree. In other words, if the are corrections (other than Brans-Dicke) for radiation problems (center-of-mass differences are probably only a few cm), then we could add to the quoted item above about "small test body." But so far, we do not have an answer, so far as I know - and if Einstein said it (which I doubt), he would perhaps have qualified it with something about CM definition and gravitational radiation (don't underestimate him - he probably realized it would exist). Pdn 15:04, 13 September 2005 (UTC)

I think that you are getting yourself very tied up in minutia here.

As I see it, due to geodesic deviation/tidal effects, each particle in an extended massive object is trying to travel a slightly different path and is thereby exerting a force on the rest of the object as it travels. The intertial/geodesic motion occurs along the path of the position where those individual forces balance. In low gravitational gradients, that should be effectively (if not identically) the center of mass.

Gravitational radiation is an intruiguing point, but I see this changes to an orbit due to it as being a reaction to its emission, and therefore a non-geodesic change.

Beyond that, I assure you the strong equivalence principle is intended to apply to self-gravitating objects too. In any case, I am a bit surprised by all this since GR very much assumes that objects ininertial motion follow timelike geodesic paths. --EMS | Talk 19:26, 13 September 2005 (UTC)

GR and QM[edit]

About QM using a fixed flat background...I'm sure I can dig out a reference for you, but I thought it was 'common knowledge' amongst researchers in the GR-QM field that one of the major discrepancies in uniting QM and GR lay in the fact that GR uses a curved spacetime whereas QM uses a flat spacetime. ---Mpatel (talk) 16:22, 13 September 2005 (UTC)

I know that it is common knowledge. I am working on a paper, and I would like to mention that. So if you know a reference off-hand, that would be nice. Thanks in any case, --EMS | Talk 19:39, 13 September 2005 (UTC)

Carl Hewitt[edit]

Hi, Ed, if you are around today, can you check with the WikiProject GTR talk page? User:CarlHewitt keeps linking his article on his cranky "theory" actors model in the theory of distributed computing with Category:General relativity, and I keep removing the links. I think I need to take this to the next step, but have no experience, do you? (It would help me if you replied on the WikiProject GTR talk page)---CH (talk) 03:30, 15 September 2005 (UTC)


You marked Category:Relativistic Information Science for deletion. Why do you believe that the article meets the Wikipedia criteria for deletion? (See Category talk:Relativistic Information Science.)--Carl Hewitt 23:39, 15 September 2005 (UTC)

Wikistress, email, etc[edit]

Hi, EMS,

I have genuinely been trying to express myself in the courteous and mild manner of a virtual Clark Kent. Maybe I've been overdoing it--- I hope my tone doesn't somehow come across as sarcasm. Anyway, I did say--- in a very understated way--- that I wish that Linas hadn't said what he did. I imagine he'll apologize to Carl H in a few days if we all leave him alone and let him cool off. Many Wikipedians (including me) have the design capacity to be much more volatile than is desirable in a utopian consensus-based community like this one. Some of us even seem to run hot and cold, as the saying goes.

So let's not all turn on each other now. I think you and I have already made it sufficiently clear that we both wish Linas hadn't accused Carl H of being someone other than Carl H. As for dotage, I think you confused Linas with something someone else said, which I also thought was regretable, and in a very understated way I said so at the time (and there has been no reoffense from that quarter, so I see no need to mention names).

I hope you won't take it the wrong way if I say that from the sound of things, you and Linas could both use a few days away from Wikipedia. You both sound stresed out about something, if you don't mind my saying so. But again, please don't get mad at me if I just said the wrong thing, since I'm just trying to smooth the ruffled waters.

BTW, I think there is some way by which registered users can email each other without publically revealing our email addies, so we should probably exchange email addresses. Also I need MPatel's new email address, if you have that. For some reason I am not getting email he sent me. I do have a filter which pretty dumps everything from a small list of email addresses, but if I can just obtain the right addresses I can easily adjust it so I exchange email with project members. That would come in handy for times like this when it might be useful to have a private discussion.---CH (talk) 03:58, 18 September 2005 (UTC)

Hello again. I decided to cease doing Wiki stuff and deleted all my talk and watchlist, but then I finally got a reply from Richard Matzner in regards to geodesic deviation (which I think I was arguing with you - if you and you can figure our who it was please pass this on if you would be so kind). I copy the e-mail in text form next, all but my name and e-mail:

From: "richard matzner" <> To: (private); "Matzner, Richard" <> Subject: Re: geodesic deviation Date: Tuesday, September 20, 2005 2:28 PM

HI Peter,

The geodesic equation is an approximation for an *infinitesimal*

  • structureless* particle.

An extended object will not follow a geodesic. If you consider moments (eg quadrupole, octopole, etc of the mass distribution, or spin), then those moments couple to the Riemann tensor and its derivatives, which modifies the geodesic equation. Similarly if you consider the mass distribution of an extended rigid body, each part 'tries' to follow a geodesic, but there is no guarantee that any part of it follows a geodesic, or if there is a geodesic, the effective geodesic is inside the body.

Generally there is no way that the geodesic deviation equation can be applied to extended bodies (even a brick is extended).

Good luck with your quibbling with your contributor!

Regards, Richard


richard matzner                     physics department
fax   (512) 471-0890                            university of texas
phone (512) 471-5062                            austin tx 78712


On 9/12/05 12:09 PM, (private) wrote:

> Richard - I have taked to editing Wikipedia (too much, I suspect) > and am in round after round of quibbling with a guy who seems to > know some GR but claims: > > a) the falling of a brick dropped off (say) a tower is explained > by geodesic deviation > > b) geodesic deviation applies to bodies separated by a finite > distance (I can field that one by asking him where he would > evaluate the Riemann tensor) > > c) Einstein assumed that massive bodies (as opposed to test > particles) follow geodesics, and that is known to be true > > and so on. I think he is regarding the Earth's CM as one particle > and the brick as another, which is way off base as I see it. I > regard geodesic deviation as handling tidal effects for test > particle swarms (and for LIGO!) > > Can you comment (for quotation) on any of these? Especially item > (c) - in fact I doubt is is true for gravity wave emitters. Is > it? I mean, in a binary neutron star system the stars are surely > not following the geodesics that would be predicted ignoring > radiation. Question is, if you include radiative perturbations, > can you still say that they are on geodesics of the total field? > > I already went into the Nordtvedt effect with him to point out > that it was not clear for a long time whether massive bodies > follow geodesics, and I claim the proof is still limited. > > THANKS if you can help > > Peter > >

By the way the reason I quit is this fuss with Carl Hewitt. Sometimes good scientists deteriorate and produce endless masses of junk - and you can't fool with it, let alone ask me to apologize. I mean, I am not touchy, but when my Wiki-"colleagues" come to the defense of such drivel or its producer, I think it is time to quit. You can find so many examples like Hewitt's - I sent already links to T J J See, but also look at: [4] from a formerly respected scientist, as well as the later (in his career) works Parry Moon, a retired MIT physics professor (he's dead as is See, so they can't put tons of links to their stuff in Wikipedia, but Van Flandern could). Moon and his colleage (perhaps his wife) Domina Eberle Spencer and colleague (perhaps their son) Euclid Eberle Moon produced such gems as "Parry Moon, Domina Eberle Spencer, and Euclid Eberle Moon Universal Time and The Velocity of Light " - Physics Essays Vol 2, p. 368 (1989). Also see The Boston Globe, “Ideas,” 9 August 1998, article by John Yemma,. with the theme that Dr. Spencer asserts Einstein was wrong. I believe Spencer is alive (in Storrs, CT) and Euclid E. Moon is in physics at MIT, in a different field, and perhaps not eager to discuss his earlier work "proving" Einstein wrong. I obviously collect crank stuff, but it is not to laugh at cranks. Truly, in some cases "cranks" produce something of interest. It is just that one has to limit the amount of time to be spent on crank items. Good bye and good luckPdn 23:47, 20 September 2005 (UTC)

Oh gosh, I dropped by to leave EMS a message on another topic. Peter, if you see this, sorry you are having Wikistress and I hope your equilibrium is soon restored.
Ed, don't know if you know who Richard Matzner is, so I'll say he is a physicist at UT Austin, well known for his work in numerical relativity (I keep a copy his paper explaining Penrose's picture of plane waves), and what he says sounds right. I can dig out a citation to a careful review paper by Joshua Goldberg from the 1962 book edited by Louis Witten (JG was a leading expert way on equations of motion back then), but you can find more recent papers on the arXiv.---CH (talk) 07:43, 25 September 2005 (UTC)

LeSage gravity[edit]

Hi, Ed, just wanted to quickly let you know that I noticed that an anon using the IP addy added back the same link you deleted a few days ago. This is the same IP addy from which that link was originally added, and I agree it looks rather cranky.---CH (talk) 07:43, 25 September 2005 (UTC)

Nigel is actually and "old friend" (as shown in talk:gravity/Archive 3 :-). In some ways I have some sympathy for Nigel, as he is like I was 10 years ago. However, he has made a set of choices such that he has stayed that way over the last decade (except perhaps for becoming more entrenched in his views).
If you looked at that archive, you may have noticed that the conversation ended with Nigel claiming that everyone is laughing at me. I concluded that he was right, if only because I kept responding to him. So in the end, this is just a matter of deleting his links when they appear. --EMS | Talk 16:57, 25 September 2005 (UTC)
P.S. This anon is identifiable as Nigel based on the URL of the link. (His machine lacks a static IP address, and so he cannot he identified based on the IP address.) I cannot see any use in taking formal action against him unless we wanted to inform his university (where he teaches) of it. IMO, the is "dirty pool" or at least an action which is not in keeping with the relatively low level of stress these links cause people. --EMS | Talk 17:07, 25 September 2005 (UTC)


I doubt you would find consensus on AfD to delete it. You could try proposing it on the talk page, but I expect that would only make matters worse in terms of inflaming the situation. Angela. 11:12, 26 September 2005 (UTC)

Hi, Ed, I want to apologize for involving you and Pdn in my ill-considered cruft patrol activity. I blame myself for having failed to consider the question of whether any of us would be able to maintain the spirit of ahimsa, and I utterly failed to consider the possibility that under stress we might actually turn on each other. I'd like to repair the damage, if I can! (I just left a note on Pdn's user talk page expressing the hope that he will return.)
About VfD, I think I now agree with Angela. I thoughtlessly joined a VfD discussion and somehow wound up at the focus of a firestorm of extra-Wikipedia threats and harrassment. The irony is that when I finally thought about my participation in the VfD (yeah, several days too late), I concluded that the best response to that particular individual is none at all: anyone (regardless of technical background) whose BS detector doesn't flash brightly upon encountering such in******nt writing is probably beyond our reach anyway :-/
However, not all such problems have such simple solutions. I have been doing some soul-searching about when and how to perform math/physics cruft patrol, and at some point we should discuss this in the WikiProject GTR pages. I plan to revise those pages soon (I know, I keep saying that and not getting to it), adding a few preliminary thoughts on cruft patrol. I am also trying to collect email addresses of project members so that we can discuss touchy issues privately as required. If I can learn what they are, I can add them to my filter (which dumps everything to /dev/null by default) so that they will pass the filter.---CH (talk) 00:33, 29 September 2005 (UTC)
P.S. Just saw your comment on Angela's talk page. Seems we all three independently reached the same conclusion, after the fact, about what would have been the wisest course of action.---CH (talk) 00:44, 29 September 2005 (UTC)
I got curious about the the JS business after a while and investigated. I quickly saw it as a mess that I did not want to get too involved with, unless it was to initiate a VfD. However, as there had already been one (as I later discovered), that seemed to tie Angela's hands. I understand your wanting to edit that page, and I agree with the content of your edits but not the spirit. At least you now see the trouble with what you did.
It may help to note that there is something in Judaism called "lashon hara", which is an edict against speeking evil about people. (Even though I am Jewish that is something that I ran across only recently due my nearly secular upbringing.) The bottom line is to realize that speaking (or writing) something bad about someone causes a hurt to that person, and that this hurt must be weighed against the good that one may do by alerting others to someone's faults. In general, gossip and the acceptance of gossip are sinful in Judaism. (However, lashon hara has it's down side: There is a story about a king who went to a meeting having been warned about the assassination plot that then resulted in his death. The king refused to accept the warning because it technically was lasohn hara.)
So I think that you know which parts of your edits of the JS page were not needed now. However, the really odd thing is that the parts of that page that are not contested are enough to define JS in -uh- terms that you would approve of.
BTW - I am willing to support any future VfD on that page, but do not and will not watch it.
One more thing: I am willing to kick your a** if and when you should deserve it. However, I will not kick it for the sake of kicking it or if it will cause you an unfair level of hurt. I could not kick you you on the JS pages (although it was tempting) without handing JS a victory that he did not deserve. Only a successful VfD would have pulled the rug out from under the both of you. --EMS | Talk 03:00, 29 September 2005 (UTC)

Useful preprint for "History of gr" article, images[edit]

Hi, Ed,

Just wanted to make sure you know about a new eprint on the influence of gtr on differential geometry. No doubt you agree this is a very important point to stress/explain in articles on the history of gtr. I haven't had a chance to read it yet, but clearly this could be a useful citation!

Also, you probably noticed that Wikimedia just introduced a new policy on images. Anything image lacking certain licenses (the key point is to allow commercial use) will be deleted. This is to permit Wikimedia to let Mandriva distribute the complete Wikipedia with future distributions. I have added a section in my tricks page and plan to add similar hints to the WikiProject GTR draft, which I need to revise. (Keep postponing that, arghghgh...) ---CH (talk) 23:48, 28 September 2005 (UTC)

Oh well, that preprint turned out to be not nearly as interesting/useful as I hoped (only discusses embedding theorems). But it is good for a laugh: in sentence n the authors state that Campbell stated his theorem in 1926 and in sentence n+1 they state that Campbell died in 1924. :-/ ---CH (talk) 00:06, 30 September 2005 (UTC)

Mathematics of general relativity[edit]


Could you pop by to mathematics of general relativity ? I think I've got the basic outline of the article sorted. Much more maths still needs to be discussed (as well as references etc...), but most of that will be dumped in other pages. I've tried to write a few words on Regge calculus, spinors, Cauchy problem etc... (left out numerical relativity - I feel burned out!) - and I know I've yet to mention embedding theorems - but I would like some feedback on the general structure of the article as it stands. TIA. ---Mpatel (talk) 15:27, 13 October 2005 (UTC)

Actor model, mathematical logic, and quantum physics[edit]

Do you think that Actor model, mathematical logic, and quantum physics is a candidate to be sent up for Wikipedia:Articles for deletion as a violation of WP:NOR?

DV8 2XL 18:24, 18 October 2005 (UTC)

Yes. I do. I have been tempted all day to add to talk:Quantum indeterminacy a "VfD anyone?" post suggesting just that. I see it as being quite NOR, with its topic being very obscure and not published in a peer-reviewed physics journal. If you wish to do that work to start the VfD, I would appreciate it.
WARNING: You will need to be brief and concise in your justification. Do note that the current content is focussed mostly on Einstein's views of QM (which is irrelvant to the issue at hand), and that the references listed all deal either with the fundamentals of QM or programming issues (as opposed to showing that any description of the purported connection between the two has been published in a reliable, professional journals). --EMS | Talk 18:47, 18 October 2005 (UTC)
Good. I will attend to this within the next 24 hours, as my personal schedule permits. I asked because my bile is beginning to rise over this user’s trollish behavior over at talk:Quantum indeterminacy and I was not sure I was being objective. DV8 2XL 20:10, 18 October 2005 (UTC)
Please consider voting Thank-you. DV8 2XL 01:51, 19 October 2005 (UTC)
Consider voting? After encouraging you to do this I most certainly will. --EMS | Talk 03:27, 19 October 2005 (UTC)



I was wondering whether you could pass your e-mail address on to me through Jitse. It would be helpful if yourself, CH and myself could communicate outside of WP. Thanks. ---Mpatel (talk) 11:28, 25 October 2005 (UTC)

Thanks EMS. ---Mpatel (talk) 15:54, 25 October 2005 (UTC)

Scalar gravity[edit]


Thank you for taking the time to rewrite the article on Scalar Gravity. This is much better than simply deleting it. We should always keep in mind that our goal is to write an encyclopaedia, and arguments at AfD which often get rather vitriolic are not as helpful as doing something constructive. -- Jitse Niesen (talk) 13:59, 12 November 2005 (UTC)

Scientific Community Methaphor[edit]

I would like you to consider voting on Wikipedia:Articles_for_deletion/Scientific_Community_Metaphor. Cheers, --R.Koot 10:49, 17 November 2005 (UTC)

re: Carl Hewitt[edit]

Yes, I already threatened him with an RfA and thats still what I'm planning to do after the AfD. Cheers, --R.Koot 20:08, 17 November 2005 (UTC)

Yes carefully read the first paragraph of the AfD ;) Seriously, if it wasn't for all those links and the excesive categories would never have put this on AfD. --R.Koot 20:21, 17 November 2005 (UTC)
Could you proofread my RfC on Carl Hewitt? Thanks, --R.Koot 21:10, 20 November 2005 (UTC)
I have requested arbitration and have listed you as one of the participants. —R. Koot 14:13, 26 November 2005 (UTC)

2005 statistics[edit]

You know your page that you made about the 2005 atlantic hurricanes, can you make a 2004 one and a 2003 and maybe a 2002 because I have problems with doing stuff like that. User:Tcatron565

Arbitration accepted[edit]

Wikipedia:Requests for arbitration/Carl Hewitt has been accepted. Please place evidence at Wikipedia:Requests for arbitration/Carl Hewitt/Evidence. Proposals and comments may be placed at Wikipedia:Requests for arbitration/Carl Hewitt/Workshop. Fred Bauder 23:24, 1 December 2005 (UTC)

Evidence presented to ArbCom[edit]

I think you should spell check the evidence you presented. It is rather annoying that some of the links do not work because you misspelt them, e.g., category:relativitstic information science and cateogry:Information science (relativistic). I don't think I'm allowed to edit your evidence (unless you give me permission). -- Jitse Niesen (talk) 16:47, 7 December 2005 (UTC)

I'm not sure what to do with the broken category links. They don't work because the cateogries no longer exist. I think that the red helps to emphsize that. [...] --EMS | Talk 21:08, 7 December 2005 (UTC)

Sorry for not having made myself clear. What I meant is that category:relativitstic information science should be Category:Relativistic Information Science (with capitals, and only 2 ts in relativistic) and cateogry:Information science (relativistic) should be category:Information science (relativistic) (with the g and o exchanged in category). If you spell them correctly, then the arbitrators can follow them (even though they are red links) and use their powers to look at what was on the page before it was deleted. -- Jitse Niesen (talk) 23:35, 7 December 2005 (UTC)

That's better feedback. Thanks. --EMS | Talk 02:23, 8 December 2005 (UTC)

time dilation[edit]

Hi thanks for your attempt to improve, but I think we can do better. See talk. Cheers, Harald88 21:22, 12 December 2005 (UTC)

General relativity[edit]

Hi, that mispelling may have been no accident. See User:Hillman/WikiProject_GTR/Bulletin# This case is not quite as clear as some I saw Sunday while trying to do some "new page patrol" (see Recent Changes button), where I saw at least anon log on from machine A, deliberately alter a word in several randomly chosen articles to resemble typos, log off, log on from machine B, and repeat. He kept it up longer than I could.---CH 05:36, 14 December 2005 (UTC)


Thanks for putting the link to the editorial on your user page. It's simply amazing! -- Jitse Niesen (talk) 21:43, 14 December 2005 (UTC)

You're welcome. I agree that it is amazing. This will bring a lot of other experts into here, through. For me, at least, I may be pushed aside in the GR area, since I am here due to a lack of other expertise.
BTW - I thank you for the added material on the quantum indeterminacy incident. I will post it as time permits. --EMS | Talk 21:57, 14 December 2005 (UTC)


I'm very impressed by the self-description of your original research on your user page. I'm certainly no expert on GR, but I know from personal experience that, even with some nontrivial credentials in one's own subfield, it can be difficult and frustrating to get a new idea into a reputable journal. Best of luck with your research, and keep on pushing! Dave Kielpinski 05:50, 18 December 2005 (UTC)


Hi EMS: I want to thank you for taking the time to vote at the wikipedia arbitration page, even if you opposed me. After all, you have the right to decide who to vote for or against (and that's what I meant by calling Wikipedia a "democratic" website, by the way, because everyone can vote any way they want to and write about any given, well known subject they want to write about, but a lot of people misinterpreted my intention when I described Wikipedia as "democratic" only one way).

Anyways I just have one question. What in my user page makes you think I'm not fit for arbitrator? I can certainly understand my statements, but my user page? Maybe you can let me know how I can fix it.

Other than that, and the vote notwithstanding, I hope we can be good wiki-friends. I think friendship-and peace-among serious wikipedia writers is vital for this website's future.

Thanks and God bless you!

Sincerely yours, Antonio Baltazar, Melchor and the other wise man guy Martin

What I wrote was:
I see nothing in his statement[s] or his user page that recommends him for this sensitive position.
I don't think that you get the gist of that. Nothing that I saw said that you are unfit. However, nothing that I saw said that you are fit either. To wit:
  • The antedotes in your user page, while interesting, say nothing of what kind of an arbitrator you would be.
  • Your candidate statement is very generic and sparse.
  • Your answers to the questions were adequate but without much in the way of substance. (For example, I care less about whether you support of oppose the so-called "Bill of Rights" as to why you have your position. I got no sense of that "why".)
There are plenty of obviously good and talented people running for this very important position. I'm sorry if this hurts your feelings, but I got no sense that you measure up to them. --EMS | Talk 03:35, 11 January 2006 (UTC)
Don't worry about it. It doesn't hurt my feelings, it was just that I was left wondering. Like I said, there are some areas where wikipedia is in fact a democratic website, and you are just excercising that democracy by voting against me. I was just curious about my user page. But my feelings haven't been hurt. As a matter of a fact, if I let my feelings get hurt by things like these, I would have been out a long time in three years I have only been voted for something once so I knew it was a long shot. Take care and God bless you. I hope to hear from you soon! Sincerely yours, Antonio The Pediholic Martin


Hi, EMS, I could sure use some support over at Wikipedia:Articles for deletion/Hyperspace. Initial voting has been very disheartening. See the talk page for my line by line critique of the first dozen lines or so. Every last one is nonsensical or wrong! ---CH 23:51, 5 February 2006 (UTC)

Wikipedia:Requests for arbitration/Carl Hewitt[edit]

A final decision has been reached in this case, and it has been closed.

For the arbitration committee. --Tony Sidaway 06:56, 17 February 2006 (UTC)

Graf's theory of gravity[edit]

Hi, Ed, if you haven't seen this eprint you should find it interesting: gr-qc/0602054. Graf is obviously trying hard to make this accessible, and his field equations are certainly among the simplest I have seen! I also like the way he systematically uses mathematical arguments to eliminate alternatives, and separates motivation by physical analogy (with low energy string theory) and motivation by mathematical analogy (with Ricci flow). Unfortunately, I am not sure I understand some things, so I am emailing him for clarification. Depending on how well I understand what I get back, I am thinking of writing a WP article on this very young theory, in part because it is a simple and distinctive theory, and in part because he seems to have tried hard to explain himself clearly, which I like to encourage! ---CH 20:42, 27 February 2006 (UTC)

Chris - I've given this a once-over. It certainly is neat, however I must confess that I think that you would be jumping the gun by putting it into Wikipedia at this time. It is very much original research under the current circumstances. Putting it into the Wikipedia article space when it has not met the basic constraints of peer review publication, being referenced regularly in peer-reviewed literature and/or being a topic of interest in the mainstream new media is a bad precedent which potentially can be a source of trouble in the future. My suggestion is to draft something in your user space, and then watch the article for citing material and for mention in the news media (which may come in the short run if people are intrigued by this article). In the meantime, I will review it for some cues on how to improve my own work (which is currently undergoing a radical revision). --EMS | Talk 04:17, 28 February 2006 (UTC)

WikiProject GTR[edit]

FYI, MP and I have been updating these pages. An important thing to be aware of is that the official (?) WP citation templates have changed since I first wrote them, so I have updated the tools page to describe the new templates. Actually I am just trying to catch up myself...

We should probably discuss taking the project public again, even though we still only have three active members (maybe two and a half, since I guess you are less active right now).

I joined Wikipedia:WikiProject Pseudoscience but am trying to avoid letting that eat up too much of my time. I might have to take some pseudoscience articles which are not directly related to gtr off my watchlist and even give up (not for the first time) on trying to help protect Albert Einstein and General relativity, ughghgh. ---CH 20:49, 27 February 2006 (UTC)

I would like to see this taken "public". I will try to devote some time to it even in the current update cycle of my paper. However, do give me a few days to get around to it. --EMS | Talk 04:18, 28 February 2006 (UTC)

Original Research[edit]

Hi Ed. I was just replying to your notes on my talk page, when I took a look at your user page. I just want to say that think it's admirable that you pursue radically different research. While I don't share your discomfort with standard GR, I think it is vital to question all theories, even (or especially) broadly-accepted ones. Your user page "thoughts on doing original research" section is right on the money. Whatever our differences on other particulars, I'm completely with you on that. (I'm also impressed by how well you keep an NPOV.) Mike -- MOBle 01:00, 28 February 2006 (UTC)

Thanks for your approval. Let's just say that early on I started down the path of recrimination and resentment and somehow saw it for the deadly (for my research) trap that it is. I have been most careful to keep some NPOV on it, while at the same time maintaining the bias that keeps the project moving forward. BTW - You may want to look into the Wikiproject GRT that Chris Hillman is trying to get off of the ground. I think that you may be an asset to it. However, you are advised to follow my lead about being NPOV with respect to one's own work and/or things that are near and dear to you (such at the Caltech web pages that you like to link things to). --EMS | Talk 04:27, 28 February 2006 (UTC)

Please check the Hilbert page[edit]

EMS, can you please check the small paragraph (and footnote) on the Hilbert page about Hilbert's Nov20-Mar 1916 paper. Particularly the claims about the maths ("variation form", explict field equation and so). I wrote it but am not 100% confident I am right. Thanks. E4mmacro 20:56, 11 March 2006 (UTC)

I don't believe that this is accurate. At the least, it is not in accord with Corry et al, who claim that Hilbert called for the use of the variational derivative in the initial version of the paper associtated with his 11/20 lecture, but did not specify it. This whole business is going to be difficult, and I think that the goal is not to state the truth so much as what the current scolarly understanding of it is. Also be advised that there is no need to go into a lot of specifiecs here. The goal of that article is to talk about the man and his carrer, not rehash the priority dispute. --EMS | Talk 04:11, 12 March 2006 (UTC)

Digital Universe[edit]

Hi, Ed, you might be interested/dismayed by my alarm over in WikiProject Pseudoscience. ---CH 18:20, 14 March 2006 (UTC)

Van Flandern POV-pushing at Speed of gravity[edit]

Well, this was inevitable and I'm surprised it didn't happen sooner. If you need/want to review Tom Van Flandern's views on "the speed of gravity" and/or my previous encounters with him, see

Now see this for my brief explanation of why the edits from the Kirkland, WA anon are characteristic of pro Van Flandern. Email follows. ---CH 21:57, 19 March 2006 (UTC)

My advice is to just keep reverting as needed. People get very frustrated when their edits don't stick. For people like TVF, this often discourages them fairly quickly. --EMS | Talk 03:20, 20 March 2006 (UTC)

LeSage gravity[edit]

I will leave the page protected right now an I hope they will accept your offer of mediation. I know nothing of the subject and have trouble even folling the discussion page. CambridgeBayWeather (Talk) 03:29, 3 April 2006 (UTC)

Thanks. If you think the page can be unprotected sometime let me know. CambridgeBayWeather (Talk) 16:37, 3 April 2006 (UTC)
Will do --EMS | Talk 16:48, 3 April 2006 (UTC)

Wikiproject GTR - improvement of pages[edit]


I was wondering if you would help to improve the WikiprojectGTR pages so we can get the project off the ground sooner. I was thinking of articles such as general relativity, mathematics of general relativity and Einstein field equations, in particular. It's been a while since some of us worked on these articles together. MP (talk) 12:07, 5 April 2006 (UTC)

Please unlock the LeSage gravity page[edit]

It's open for editing. Good luck. CambridgeBayWeather (Talk) 05:26, 10 April 2006 (UTC)

Thank you very much --EMS | Talk 16:13, 10 April 2006 (UTC)
SneltCatNoc (ContactLens, probably a shill for 63.24...) has done a full revert. I want to undo this & tell him to edit the section if he wants. Please Advise April 27, 2006 User: LeSagian

Black holes[edit]

Hello. Sorry to use Wikipedia as a soap box. But in case you're interested, there's another more technical reason to be against black holes besides those you mentioned. Black holes, by definition, come with event horizons. Horizons emit Hawking radiation, which is thermal radiation of every free scalar field in the theory.

Some theories, like quantum electrodynamics (QED), when you quantize them using the Faddeev-Popov procedure have fields called ghosts. These are unphysical fields, in the sense that if they show up as external states then your theory is sick (it has negative norm states, and negative probabilities). But they are also real, in the sense that as virtual particles they contribute to observables (although these contributions can be reinterpreted as determinants in the path integral) and these contributions have been well-tested experimentally (in QED actually they don't contribute, but they do in QCD and in gravity, although the contribution to gravity obviously hasn't been experimentally verified.)

Anyway, the ghosts in QED are free scalars, and so Hawking radiation produces them. This makes the theory sick. That is, using a standard probability theoretic definition of density matrices you get negative probabilities. If for some reason the horizons weren't there (which would mean no black holes) then there wouldn't be such a problem.

Sorry to be so longwinded and self-promoting, but I was pleased to find someone else trying to kill black holes. So here's a final act of self-promotion: Killing Horizons. JarahE 19:00, 22 April 2006 (UTC)

LeSage gravity page[edit]

Hi EMS. The users anon #63, ELQ22 and SneltCatNoc (really all the same person) are now vandalizing the article. He's removed reputable references like the Radzievskii reference and has made the "current status" section into a stub. I don't think there will be any stopping this individual. I would like to restore to an earlier version and have some greater protection for the page if possible.MRE 18:26, 4 May 2006 (UTC)

Huh? Ems, you are re-inserting Evans as reference? One of us must be somewhat off. Please have a look at: [5]. Or is that another Evans? --Pjacobi 21:12, 4 May 2006 (UTC)
For the record, Myron Evans =/= the Jim Evans mentioned in that discussion. (By the time I made this comment, PJ had already realized this.)
Ed, I think I saw somewhere someone from the old sci.physics.relativity crowd attacking you as a crank, but then I couldn't find it again! I'll try again later and put in a good word for you on the offenders talk page. BTW, it might be a good idea to find an admin and have them do a partial block on that article, which will at least prevent anon edits. Then we would only have the civility and possible sock issues to deal with, and I suggested the registered users take a break until tempers cool.---CH 21:22, 6 May 2006 (UTC)
MRE, are you sure that the anon (aka anon #63), ELQ22 and SneltCatNoc are the same? It seems plausible based on style, but did you ask for a user check? ---CH 21:23, 6 May 2006 (UTC)

Bell's spaceship paradox[edit]

Hi, FYI User:Pjacobi and I have been arguing with User:Rod Ball about this article, which I recently rewrote together with Rindler coordinates. We have been trying to tell him that a simple computation shows his view is wrong, but he is accusing me of bad faith, blustering, ignoring his arguments, etc., and now he is reverting the version I wrote, which I think was a huge improvement over the original. I have offered to try to rewrite the last paragraph of my version somewhat, but arguing with him is growing very tedious. Pjacobi and I have no doubt that the view we describe as mainstream is in fact the mainstream view, but Rod Ball rejects this, and is even demanding that I survey physicists :-/ If you have a chance, it would probably be good to have some input from another user! ---CH 16:52, 9 May 2006 (UTC)

This may be moot, since I think I found precisely where his error occurred, and hope he will shortly concede his goof. ---CH 07:52, 12 May 2006 (UTC)

Sigh... my optimism was misplaced, and I could use some help on the talk page.

User:Rod Ball can't seem to understand his own diagram, and he continues to insist that the mainstream viewpoint, as presented in the current version of the article and in the sci.physics FAQ, is not only incorrect but not even the mainstream! In the last section on the current talk page, called User:Rod Ball's error?, I expose his error(s). It seems clear that in his depiction of Rindler observers in his diagram, he is either

  1. confusing hyperbolic arc length with hyperbolic angle, or
  2. confusing Rindler coordinate time with elapsed proper time since Rindler time t=0 (which is also Cartesian coordinate time T=0), as measured by the Rindler observers themselves.

In addition, Ball insists that the standard notion of four-acceleration as the covariant derivative of the unit tangent vector to a timelike curve is incorrect, and he fails to understand that this standard notion agrees with path curvature. Since this standard notion corresponds to what an observer riding the world line will measure, it is the only notion which deserves the term "proper acceleration". But Ball seems to denote some private concept by that term, and seems to ascribe this notion to J. S. Bell or W. Rindler (he must have misunderstood something he read). ---CH 19:51, 13 May 2006 (UTC)

Bios theory and User:Lakinekaki[edit]

AFAIK, Chaos theory is not on your regular beat :-/ and probably neither of us really needs to experience any further outrage over nefarious self-promoting activities at WP, but, gosh, this one really seems to take the cake. See my comments on Talk:Bios theory. ---CH 07:52, 12 May 2006 (UTC)

Thanks for voting! I hope this is soon resolved satisfactorily.---CH 19:52, 13 May 2006 (UTC)

First postulate[edit]

In the mentioned book, Pauli indeed is of the opinion, that the 1st P. outrules the ether, "as all movement is relative no frame can be said to absolutely at rest" (not literally cited). Furher exposition in that paragraph also seems to indicate, that he has the MM experiment in mind. The 1st P. would imply that the MM experiment gives the same result in all inertial frames (as it as closed system).

I'd say not this not waterproof against stubborn aether fans, as they would argue, that there is no need to call the motion relative to the ether "absolute motion" and no optical or EM experiments is a closed system, as it interacts with the ether.

Pjacobi 18:37, 13 May 2006 (UTC)

I see what you are getting at. Indeed, Einstein is very much taking direct aim at the aether theories with the first postulate. As he put it
"... the same laws of electodynamics and optics will be valid in all frames of reference in which the equations of mechanics hold good".
Yet that still leaves a question as to what is meant by the "laws of electrodynamics and optics" and the "equations of mechanics". After all, given appropriate "laws" and "equations", you can have an aether theory that is compatible with the first postulate. However, in the first paragraph of his article Einstein makes it clear that he is looking for "laws" and "equations" that do not distinguish between one frame of reference and another. Just before introducing the postulates, Einstein himself declares that the MMX and related observations show that
"the phenomena of electrodynamics as well as mechanics possess no properties corresponding to the idea of absolute rest".
In this vein, Einstein is outruling the aether theories even before he has introduced his postulates. In essense, the aether theories being outruled is now the goal of the postulates. So as I wrote above, the first postulate takes aim at the aether theories. However, it is the second postulate that blows them out of the water.
So I ask you to be careful. Please remember that it was not Einstein who devised the first posulate. Instead, it was Galileo who did that, and it was one of the founding principles of classical mechanics. Einstein's genius was in deciding that the principle of relativity itself was more important than any edifice that had been built on top of it. However, you cannot use that principle to outrule the aether theories without imposing another principle on it (such as the lack of an "absolute rest frame" for electrodynamic phenomena). BTW - Do remember that the aether theories were patterned after the observations of the behavior of sound in air. So do not think that the aether theories were ill-conceived. After all, for sound, the rest frame of the medium in which is travels is a prefered frame. --EMS | Talk 03:59, 15 May 2006 (UTC)

RFC Endorsement period expired[edit]

EMS, quoting the section of the project page:

In order to remain listed at Wikipedia:Requests for comment, at least two people need to show that they tried to resolve a dispute with this user and have failed. This must involve the same dispute with a single user, not different disputes or multiple users. The persons complaining must provide evidence of their efforts, and each of them must certify it by signing this page with ~~~~. If this does not happen within 48 hours of the creation of this dispute page (which was: 01:41, 12 May 2006 (UTC)), the page will be deleted.

It seems that the 48 hours period has expired but I notice that the page has not yet been deleted. Since I can't find a way to delete it, and since you have some experience with this, can I count on you to take the necessary steps? Thanks, DVdm 13:50, 15 May 2006 (UTC)

I am going to let the thing sit around for another day or two, before asking an administrator to rule on it's status (if they have not noticed it first). I'm not sure if Cadwgan could be considered as endorsing it or not. If not, it will be dropped. If so, it will undergo some formality and then be dropped. Either way, you will be off of the hook soon enough, but do be aware that this type of avenue is out here, and that if you make a habit of doing newsgroup style flaming that you will be held to account in this manner sooner or later. --EMS | Talk 14:45, 15 May 2006 (UTC)

Page seems to be deleted now. Cheers, DVdm 13:09, 19 May 2006 (UTC)

Reputable sources[edit]

EMS, I asked you to clarify your claim on my page that a paper that apparently was published in Foundations of physics, "was not published in a reputable source"; and on the special relativity discussion page you apparently continue to discredit the information that is contained in such sources. Thus, please clarify. Harald88 06:57, 16 May 2006 (UTC)

Clock synchronization question.[edit]

Due to the debate over at Talk:Special relativity, I have been thinking about the issue of clock synchronization. Specifically, I've been working on the following thought experiment. Consider two co-located particles at rest in an inertial frame. The clocks associated with each particle are identical and are synchronized. At time t=0, the particles began to accelerate in opposite directions. At time t = T/2 as determined by the particle clocks, the direction of acceleration of each is reversed. Then, at time t = T as determined by the particle clocks, the acceleration of each returns to zero. Further, the particle accelerations, as measured by accelerometers associated with each particle, are at all times equal but opposite and constant. In other words, the two particles undergo constant equal but opposite proper acceleration first away from each other for proper time T/2 and then towards each other for proper time T/2.

According to SR and due to the symmetry of the particles world lines, the particles will be at rest w.r.t. each other after the accelerations have returned to zero. Further, the proper time elapsed for each particle since the accelerations began is the same. The particles may now exchange light signals and measure the time required for light to propagate from one particle to the other. Of course, the time will be the same in either direction.

However, it occurs to me that no explicit synchronization at a distance has been performed here since the particle clocks were synchronized when they were co-located. Also, at all times, I have referred to the proper times and proper accelerations so that clock synchronization in the inertial frame does not enter the picture. Yet, this method, according to SR, will give the same result that Einstein synchronization does in all inertial frames of reference - isotropic one-way speed of light. So, somehow Einstein synchronization must enter into this thought experiment.

Thus, I am lead to believe that my specification of using proper time and local accelerometers must do this. In other words, any other theory that is consistent with a frame invariant value of c for the two-way average speed of light (such as LET) must change the result of this experiment and to do this, it would have to change the way proper time and proper acceleration are determined. Yet, it seems to me that the outcome of this would be that, for any other theory, the particles would not be at rest w.r.t. each other if the elapsed proper time is the same. Or to put it another way, if the particles are at rest w.r.t. each other at the end of the accelerations, their clocks would not longer by synchronized in a way that would give isotropic OWSL in all inertial frames.

I suppose where I am leading with this is the question of, if I have come to the correct conclusions above, why this experiment could not be used to test for the 'real' one-way speed of light. My gut tells me I must have a hidden assumption here that I haven't discovered. Do you see it? Alfred Centauri 19:21, 23 May 2006 (UTC)

The problem is less with your thought experiment than with Cadwgan's carefully-crafted-to-be-confusing request. Here is the issue: To test the one-way speed of light between at-rest clocks, the clocks must be synchronized. Yet the way you synchronize clocks in relativity is to assume the isotropy of c and set clock B based on the assumption that it received a pulse (going back and forth between A and B) midway beween the successive times that the pulse arrives at A. [Example, A sends out a pulse at time 0. B gets coded pulse (to note time 0), and sends it back. A gets pulse at time 10, and sends it back towards B noting the time of 10. B gets pulse, sees that the round-trip time is 10, assumes that it gets the pulse at half of the round-trip time (being 5 units), and sets its current time to 15 (being the time the pulse left A plus the inferred one-way time]. Now, it is ridiculous the use the A to B time to measure the speed of light, because as Cadwagan correctly inferred, we have set our clocks based on the assumption of that which we are testing!
However, there are two "outs" here. One is to check the B-A synchronization, since if the speed of light is not uniform and isotropic, using that assumption to set the A-B synchronization will mess up the B-A syncronization when the A-B abd B-A propogation times differ. The other possibility is to measure the course using rods and see it the distance/time result is the known speed of light.
As for the exercise itself: Symmetrical time dilation will naturally leave the A and B clocks resynchronized once they return to rest in the inertial frame of reference in which the symmetry occurs. However, given a clock C which was synchronized with A and B before they were accelerated but which was not accelerated itself, synchronization is not restored by clocks A and B returning to being at rest with respect to it. Instead clocks A and B will have lost time due to their relative motion wrt C, and that displacement of elapsed proper time will persist afterwards. Also, while A and B are in motion with respct to the starting frame, their clocks are not synchronized in their instantaneous inertial frames of reference. --EMS | Talk 20:22, 23 May 2006 (UTC)