A baffling quote from Einstein, badly requiring explanation

[atyy]

In physics we do distinguish between "physical" coordinate-invariant facts and coordinate-dependent ones, though. Am I right in thinking there is no coordinate-invariant notion of a spatial geodesic in GR, unlike with spacetime geodesics which are coordinate-invariant and thus give a coordinate-invariant way to define the curvature of spacetime with differential geometry?

Well, that's true in Minkowski space, and Minskowski space is a vacuum solution of GR, so it's true in GR.

 

[echoing song]

To DaleSpam:

The century's worth of experimental data you refer to just means that as a mathematical coordinate of spacetime of course time should have been given the equal status it was in fact given. But I'm talking about its role in the MODEL (at least what I see as the only reasonable model) generating our understanding of what underlies it all physically—there it's the kid brother, just tagging along.

DaleSpam, please, for one instant put aside your preconceptions on this topic and consider this: Don't you feel it's the curvature of space in the presence of masses that is the juggernaut that controls everything else in GR, and specifically, that FORCES a curvature upon time? THAT'S why I think the model of reality we conjure up must give space's curvature the decisive role.

Here's an analogy: DaleSpam, who do you consider to be the more important figure in deciding the gender of a baby, the mother or the father? Based on your reasoning thus far, you would say they have equal status, each contributing a vital chromosome. But I would say the father, since it is solely his contribution that makes a difference—if he provides a Y it's a boy, an X it's a girl. Once his contribution is made EVERYTHING ELSE IS DETERMINED. Once space is curved, everything else is determined. Time is as powerless as the mother to change things. Now, from the technical viewpoint of a geneticist, both parents' contributions are equal, just as from the technical viewpoint of a mathematician, both space and time are on an equal footing as coordinates. But from the perspective of someone looking more deeply, one is the guiding force, the Determiner, and the other just a taken-for-granted corollary. Yes, the X chromosome supplied by the mother must do what it does in order for the baby's gender to be properly established, but what it does is completely imposed upon it by the father's X or Y contribution. Similarly, time must play its role in order for spacetime to function, but the role is that of obedient servant, or really chattel slave, everything driven by the curvature of space's relentless whiplash.

 

[atyy]

THIS GRAVITATIONALLY-INDUCED CONVERGENCE ONLY OCCURS BECAUSE OF THE OVERALL CURVATURE OF SPACETIME, WHICH ITSELF IS THE CONSEQUENCE OF THE LITERAL, PHYSICAL CURVATURE OF SPACE.

Sometimes it works to think like that, but not always. See the comments before and after Eq 4.77 in Gourgoulhon's http://arxiv.org/abs/gr-qc/0703035.

And then you also need the spatial curvature to evolve in time. Eq 4.78 and following.

 

[Dale]

The century's worth of experimental data you refer to just means that as a mathematical coordinate of spacetime of course time should have been given the equal status it was in fact given. But I'm talking about its role in the MODEL (at least what I see as the only reasonable model) generating our understanding of what underlies it all physically—there it's the kid brother, just tagging along.

I don't understand your comment here. In normal usage a theory's "model" is the mathematical framework used by the theory to make experimental predictions. In the case of relativity the mathematical model is the Minkowski geometry of spacetime. You appear to separate the two somehow. So what do you mean by "the MODEL" and which theory's model are you referring to where time is not on the same footing as space?

Don't you feel it's the curvature of space in the presence of masses that is the juggernaut that controls everything else in GR, and specifically, that FORCES a curvature upon time?

No. Go back to the sphere analogy. You can have a sphere where the east curvature is equal to the north curvature, you can also have a prolate spheroid where the north curvature is less than the east curvature or an oblate spheroid where the north curvature is more than the east curvature. The two are not always equal, but only in the case of specific symmetry. Extending the analogy to spacetime, the time and space curvature are equal in the specific case of the Schwarzschild metric but not in general.

 

[feynmann]

Thank you Ich for the link and A.T. for the link and the comments—I found them very instructive. It's odd but I never before encountered an explicit division of space-time curvature into 'curvature of time' with specific effects and 'curvature of space' with another, separate set of effects—together accounting for the whole.

Am I understanding you (and the links) correctly in concluding that the commonly experienced effects of gravity—falling objects, the Earth's orbit around the sun-- are NOT in fact due in any significant degree to the curvature of space but rather to the curvature of time? Exactly how does that work with regard to, say, an object falling off a table? How do you explain that—not in terms of a force accelerating the object, but by gravity curving time? And why do the two approaches yield essentially identical results in ordinary, everyday circumstances?

Per Schutz's book, <Gravity from the Ground Up>, "All of Newtonian gravitation is simply the curvature of time" See this link: http://www.gravityfromthegroundup.org/pdf/timecurves.pdf

 

[echoing song]

To DaleSpam:

Maybe I'm on a senseless, quixotic quest; perhaps I should cease pursuing this point so implacably. What impels me? I have no “professional” relationship with relativity, nor will I ever—at no time will I have to deftly manipulate Ricci tensors like a juggler does bowling pins, and though I admire both skills, I aspire to neither. No, I simply seek a MEANINGFUL understanding of as many of GR's underlying concepts as possible. I want to undergo (in a more modest way of course) the same process of enlightenment that Einstein did as he struggled to synthesize a theory of gravity from say, 1907 to 1912 or so—BEFORE he and Marcel Grossman (his former classmate, his friend, and let's face it, his math tutor) sat down and hammered out the intricate mathematics.

So, to answer your question directly, THAT is what I intended by a 'model'--perhaps I used the word unscientifically, I apologize. I meant a non-mathematical, usually visual, representation of some process in the real world, a depiction that seeks to replicate the basic physical principles at work. (I said 'usually visual' because I once read somewhere that Einstein sometimes imagined, AND SOLVED, problems in physics by tensing and relaxing certain muscles, whatever the heck that means.)

Specifically, in this case, I'm trying to get an entirely non-mathematical sense of what is physically at the root of GR. In the simplified accounts of GR (and I'm familiar with none but that kind) curved space becomes crucial after Einstein reasons his way past gravity as a 'force'. And while even 'surfaces' in curved space can't truly be 'visualized' by our Euclidean-bound minds, I still can get a 'feel' for what curved space means and how it would operate. And it wasn't difficult to imagine entwining it with time in the way Minkowski foreshadowed in his famous 1908 quote about time and space as independent entities fading away. And then came this past Thursday, when, after submitting my question about the Einstein quote that seems to resurrect the concept of 'force', I heard for the first time about 'the curvature of time' and how IT was responsible for all the everyday effects of gravity, with 'the curvature of space' reserved for esoterica like precession.

DaleSpam, this may simply demonstrate severe limitations on my part, but 'the curvature of time' to me can only be a figurative, mathematical concept—it has no literal, physical meaning. Plotting time graphically and having its line or dimension curve figuratively as it interacts in spacetime with a graphic representation of a LITERALLY PHYSICALLY curved space makes perfect sense. But time itself as physically curved is a complete non-sequitur, like describing 'existentialism' as high in carbohydrates. What is 'time' that it can HAVE a curvature?? Events occur in sequence—that's the passage of time. What does it mean to say that it is literally, physically curved? It seems meaningless to me, while I can imagine, at least approximately, space as literally, physically curved. And in trying to create a meaningful 'model', in my sense of the term, I can only allow entry to concepts that make physical, visual sense. Otherwise I'd just be pretending to understand.

Is there anybody out there who shares my problem with the curvature of time, or agrees with my way of reconciling things (in an earlier post)? To a hypothetical Silent Majority in cyberspace sympathetic to my position—it takes just seconds to register and express your views. It's fun to participate and you don't have to be the type that solves second order partial differential equations between spoonfuls of Rice Krispies every morning. Good questions, intelligent comments, shrewd analysis often comes from those without years of formal training. And I must say that my being this lone 'voice crying in the wilderness' on this issue is getting PRETTY DARNED ANNOYING. I'm realizing that I make a rotten John the Baptist.

 

[Dale]

I meant a non-mathematical, usually visual, representation of some process in the real world, a depiction that seeks to replicate the basic physical principles at work.

Then I encourage you to think more on my sphere analogy and to spend some time seriously studying the figures A.T. linked to in post 8. It doesn't require any math, but it does take some mental effort.

this may simply demonstrate severe limitations on my part, but 'the curvature of time' to me can only be a figurative, mathematical concept—it has no literal, physical meaning.

It is literal and physical, but I wouldn't say your discomfort with it is a "severe limitation". All it requires is some study. However, I would recommend that you start with SR. The math is easier, the geometry is flat, the experimental evidence is more complete, but the unification of space and time is the same.

 

[christina p]

I've noticed that while some people in this thread have insisted that the 'curvature of time' is literal and physical, no one (including DaleSpam, who is the most outspoken proponent of this position) has actually explained how in fact time can be literally, physically curved. Merely asserting it is not enough.

How do you refute echoing song's statement that “Events occur in sequence—that's the passage of time. What does it mean to say that it is literally, physically curved?” echoing song's point seems self-evidently true. I think he's right that curvature with respect to time cannot possibly have literal, physical meaning only figurative and mathematical.

 

[feynmann]

What is 'time' that it can HAVE a curvature?? Events occur in sequence—that's the passage of time. What does it mean to say that it is literally, physically curved? It seems meaningless to me, while I can imagine, at least approximately, space as literally, physically curved. And in trying to create a meaningful 'model', in my sense of the term, I can only allow entry to concepts that make physical, visual sense. Otherwise I'd just be pretending to understand.

It's not hard to know what it means physically when we say that time is curved: it means that the rate at which clocks run changes from place to place, even when the clocks are at rest with respect to one another. The curvature of time is in the gravitational redshift, and the gravitational redshift is enough to insure that freely-falling bodies follow their Newtonian trajectories.

 

[christina p]

Grab your dictionary, feynmann and look up 'literal' and 'physical'. Your answer makes my (and echoing song's) point in spades! You are using the term 'curvature' figuratively. A changing rate at which clocks run is in no way a literal or physical curvature, though when expressed graphically as a dimension it may appear figuratively curved! Figuratively, feynmann, figuratively!

 

[gmax137]

I don't understand the distinction - I mean, I have a hard time "visualizing" curvature of either space or time. When you say you can see the curvature of space, do you mean, you can draw an x- and y- axes on a flat piece of paper, and then 'bend' the paper up in our three-d world? If that's it, why not just draw x- and t- axes, and then bend the page? What's the difference in your mind? Or am I completely missing the point here? Believe me, I've missed a lot of points before...

 

[Dale]

I've noticed that while some people in this thread have insisted that the 'curvature of time' is literal and physical, no one (including DaleSpam, who is the most outspoken proponent of this position) has actually explained how in fact time can be literally, physically curved. Merely asserting it is not enough.

I am afraid that you may have misunderstood the main thrust of my argument with echoing song, as often happens in an internet discussion. My main point of disagreement with echoing song has been his unwarranted assumption that time is somehow not on equal footing with space. This is actually a much more important point than the curvature since it applies in flat spacetime also. What is your position on that topic?

 

[feynmann]

Grab your dictionary, feynmann and look up 'literal' and 'physical'. Your answer makes my (and echoing song's) point in spades! You are using the term 'curvature' figuratively. A changing rate at which clocks run is in no way a literal or physical curvature, though when expressed graphically as a dimension it may appear figuratively curved! Figuratively, feynmann, figuratively!

So you have difficulty to see curved time is "physical". First we need to know what time is? Einstein explained: well, time is what clock reads. Good, that's simple enough. Let me ask you a question, if time is not "curved", how can the clock at 2nd floor runs faster than the clock at ground floor? Think about how tanks turn, suppose it wants to turn to the left, what it does is to speed up its right track. That's the same, since you and clocks travel in time at all times, but how? How do you travel in time in a gravitational field, straight or curved?

 

[Nickelodeon]

Is there anybody out there who shares my problem with the curvature of time, or agrees with my way of reconciling things (in an earlier post)? To a hypothetical Silent Majority in cyberspace sympathetic to my position—it takes just seconds to register and express your views. It's fun to participate and you don't have to be the type that solves second order partial differential equations between spoonfuls of Rice Krispies every morning. Good questions, intelligent comments, shrewd analysis often comes from those without years of formal training. And I must say that my being this lone 'voice crying in the wilderness' on this issue is getting PRETTY DARNED ANNOYING. I'm realizing that I make a rotten John the Baptist.

I'm going to get shot down in flames here but as I see it it doesn't matter how you measure time, whether it is with a pendulum, a vibrating crystal or a caesium fountain atomic clock, if you rely on a physical system, the mechanics of the measuring equipment will be effected by its inertia ie. the impact of gravity, its acceleration, or its speed through the universe. The beat of time becomes even more wobbly when you use light as the data carrier.

In a variable time universe, such as favoured by Einstein, the speed of light doesn't vary and, should you attempt to go faster than this, then time is the side of the velocity equation that is modified and will prevent you achieving this. The faster you go the slower your time will go.
However, you could choose to live in a constant time universe where in this case light will travel at different speeds depending on the strength and direction of the local gravitational field. You just need to alter the maths accordingly.

 

[matheinste]

Hello Nickleodeon.

Unfortunately we don't get to choose what sort of universe we live in.

Matheinste.

 

[Mentz114]

echoing_song ,

you seem to have a problem with the use of the term 'curvature' more than anything else. You argue that time cannot have this attribute, and you use the everyday meaning of the word. Well, you're right, well spotted. But it's irrelevant because the term 'curvature' in GR is a precisely defined mathematical condition and does not have the everyday meaning ( see for instance any book on GR, but especially the Carroll lectures ).

M

ps please don't capitalize words. The last time I saw that was in a mad tract.

 

[overzealous]

As an interested amateur, I felt compelled to register just to pose some questions about issues raised by this thread, questions which I hope will be answered by the experts in as explicit and jargon-free a manner as possible.

Consider the prototypical gravitational event: a rock is released 16 feet above the surface of the Earth and after a second or so arrives at the surface.

The consensus of the experts in this thread appears to be the following:

1)Despite Einstein's reference in the quotation that occasioned this thread to a “Newtonian field of attraction”, the rock does NOT reach the surface because of a force acting in accordance with the inverse square law, or any other force, but by an entirely different mechanism, although for unexplained reasons this mechanism's outcome almost precisely mimics the inverse square law's results.

2)Though the geometry of spacetime exists as a coherent whole, it is often useful to think of certain gravitational events as happening largely or perhaps entirely as a result of either the space component or the time component. (Some, like the deflection of starlight, is an exactly 50-50 combination.) So, in this instance, the fact that masses do indeed induce curvature of space is essentially irrelevant in explaining the behavior of the rock.

3)The mechanism involved with the rock's gravitational acceleration concerns time, either primarily or exclusively.
The question is, exactly how? Gentlemen, the rock has just been released. Some odd, counter-intuitive things are apparently about to happen to time (does that mean, 'to light'?). These things have nothing to do with force or with the Earth's effect on space's geometry. So tell me, representing all the interested amateurs visiting this site, exactly what happens to time and why that results in the gravitational acceleration of the rock.

 

[A.T.]

but by an entirely different mechanism, although for unexplained reasons this mechanism's outcome almost precisely mimics the inverse square law's results.

What is there to explain? Both models (inverse square law force & curved space time) are designed to yield a result that matches the same observation.

So, in this instance, the fact that masses do indeed induce curvature of space is essentially irrelevant in explaining the behavior of the rock.

Curvature of space affects only objects that move trough space. So as soon the rock starts moving it is affected by space curvature, but not very much due to it's low speed.

3)The mechanism involved with the rock's gravitational acceleration concerns time, either primarily or exclusively. The question is, exactly how?

The question "how" is answered exactly by the math. If you want nice pictures of the machanism: http://www.relativitet.se/spacetime1.html" . If you want a crude analogy: The rock advancing trough spacetime steers towards the area of slower time(~=denser spacetime), similar to a light ray advancing trough a medium with varying optical density also steers towards the area of higher optical density.

 

[Mentz114]

Overzealous,
it's customary to welcome new posters here, but I don't think you're a new poster. Your misunderstanding of the scope and meaning of a scientific theory is obvious from your absurd line of questioning, your stuttering logic and petulance.

Your first point is wrong. In a weak field the inverse square law is recovered ( as A.T. points out.) Why do think a Newtonian force is more 'real' that space-time curvature ? It's just a word introduced to explain the attraction. If I asked you to define force, you'd probably say it is what moves the rock.

The second point is also incorrect. Why can we not explain the rock's behaviour using space-time geometry ? We can and do, with great success.

In the third point you state "These things have nothing to do with force or with the Earth's effect on space's geometry. " How do you know this ?

Your 'arguments' have no scientific value, based as they are on a failure to understand what a scientific theory is, and what appears to be complete ignorance of GR.

 

[neopolitan]

echoing_song ,

<snip>

ps please don't capitalize words. The last time I saw that was in a mad tract.

Random capitalisation does seem to be a common theme in papers written by the patently insane.

I do think that echoing_song was capitalising with a purpose though. The English language, like most as far as I can tell, does a poor job of translating the spoken word in written word. Emphasis is particularly poor and I think that that is what echoing_song was after.

You may want to look at your recent posts together Mentz. Not many of them are missing an insult. While I freely admit that I have been less than gentlemanly towards you in a couple of posts, you seem to have insulted me - who apparently needs to be cured of something, obliquely insulted echoing_song by implying capitalisation related madness and, amusingly enough, gone to town on a chap claiming to be overzealous incarnate - "stuttering logic and petulance", plus "complete ignorance of GR". And that is in just two threads, I daren't look in more. Perhaps you need to take a deep breath or two?

cheers,

neopolitan

 

[overzealous]

Showing unusual maturity for one of my tender years, I'm going to ignore the fact that another commenter attempted to insert me bodily into his Cuisinart set on puree, for no apparent reason. I'll just follow the splendid example of my Granddad, who hailed from Laredo, Texas. In situations like this he'd fix the malefactor with his iciest stare, shake his head in mild disbelief as though puzzled at how God's creations could possibly sink so low, and murmur, “If that's all you got, pardner, then you ain't got nuthin'.” He drawled that last word with a growing softness that asymptotically approached silence, becoming the very thing it was describing. And the object of his scorn seemed to become that too, as you watched.

Now to more important matters-- I want to respond to a comment made by A.T. In my post, I parenthetically noted that the near identity of the results of Newton and GR in everyday gravitational situations was curious and worthy of explanation. Here's his comment:

“What is there to explain? Both models (inverse square law force and curved spacetime) are designed to yield a result that matches the same observations.”

If one theory (Newton's) has as its basis a mechanism totally different from that of the other theory, then it is indeed odd if they make predictions that are identical to double-digit decimal places, and it demands explanation, providing the following is true: Namely, if the remarkable accuracy of Newton is not due to the kind of thing that Ptolemy's geocentric theory did to make its predictions conform to reality--adding epicycles and deferents and all sorts of ad hoc absurdities that together created an utterly senseless, implausible, contrary-to-nature monstrosity. But, of course, Newton's gravitational equation is sleek and elegant, and logical too—the absolute antithesis of Ptolemy's theory, and other failed theories in the past that were arbitrarily twisted and tweaked until they matched observations.

That established, perhaps the explanation is nothing more than that GR is like some equations of SR, which, as velocities approach zero, literally reduce to the familiar Newtonian formulations. However, since I'm not conversant with Einstein's field equations (I'm just an interested amateur) I can't say if that is or isn't the case. But if Einstein's equations don't mathematically reduce to the Newton equation, but still yield nearly identical results in everyday situations, then that's really interesting.

Actually, I just had another thought. Even if Einstein does mathematically reduce exactly to Newton as velocities approach zero, it's still odd. Why would theories employing completely different mechanisms for gravity, with one being right and the other wrong, do that? But maybe it's not really true that they do employ completely different mechanisms, maybe that quote of Einstein's this thread started out with (about Newtonian attraction) indicates just that—since I only know the rudiments of GR, I'm in no position to say. It would be great if someone more knowledgeable than I on this subject (which is just about anyone in this forum) could comment.

 

[Mentz114]

overzealous;

But if Einstein's equations don't mathematically reduce to the Newton equation, but still yield nearly identical results in everyday situations, then that's really interesting.

You've been told by at least two people that GR does give Newton's gravity in non-relativistic regimes. The derivation is an elegant piece of mathematics ( see for instance Stephani pages 89-91).

Why would theories employing completely different mechanisms for gravity, with one being right and the other wrong, do that?

It's not accurate to say one ( GR ?) is right and the other (Newton ?) is wrong. They are applicable in different regimes, with a considerable overlap.

Your reference to 'mechanisms' is also making unwarranted assumptions. Most theories of gravity do not have anything to say about this. GR and Newtonian gravity both invoke an abstraction which can be quantified and lead to a theory that gives accurate predictions through numerical calculations - there is no mention of any 'mechanism'.

Therefore you cannot assume that because one theory speaks of forces and the other of space-time geometry, that there is any contradiction you can use to stir up doubt and dissent.

 

[ccollins919]

Hey, overzealous. I'm a newbie here but the way I see this question of Newtonian vs gr as well as a few other comparisons concerning the evolution of scientific principles is that it simply comes down to energy. Newtonian, and I would say 'real world', physics is accurate enough as long as you don't dig too deep or go beyond a certain energy or speed threshold. But in the high energy world of the micro, the time intervals are shorter, the energies higher, and the measurements and mathematics to describe all this has to be more exacting. It's not too surprising that some of these models yield similar results because at their extremes they often overlap, but usually one takes over in the domain of high energies and lofty ideals just where the 'older' models leave off.

 

[overzealous]

To Mentz114:

Talk about “unwarranted assumptions”! The idea that I want, to quote you, “to stir up doubt and dissent” about GR is an imputation of motive that would make my 'little round belly shake like a bowl full of jelly' from guffawing, if I didn't have high-carbon steel washboard abs.

Mentz114, let me say this very slowly, enunciating each syllable with Shakespearean-actor-like precision to avoid even the possibility of ambiguity, uncertainty, or misinterpretation: I love Einstein, I can't believe I'm privileged to share the same species designation with him. Forget relativity for a moment—just examine his proof of the Pythagorean Theorem fashioned at age 12. There are literally hundreds of nominally different proofs of it (including one by US President James Garfield!) but they all have one thing in common: they simply prove the theorem and nothing more. But Einstein saw a deeper principle at work, of which the Pythagorean Theorem was just a special case! An insight so penetrating it escaped not only Archimedes and his pals, but Fermat, Newton, Euler, Gauss, Riemann—and Einstein was only twelve years old, for goodness sake! And math wasn't even his strong suit!

So please don't misinterpret questions prompted soleley by a desire to make sense of things as somehow seeking to undermine Einstein.

Now, Mentz, since in your last post you put aside the gratuitous vitriol (though I don't think one would yet mistake you for a cuddly teddy bear), I can take you seriously as a person and learn from you. And I have. Thank you very much for your explicit reference to a derivation by Stephani that in fact shows Einstein reduces precisely to Newton's familiar equation in non-relativistic settings. While I'm sure the math would be well beyond my present capabilities, it's very valuable to know such a relationship exists. That a curved spacetime analysis can be exactly equivalent to a traditional inverse square force analysis under certain circumstances must say something interesting about both, if only I knew enough about GR to hear it! But one thing I can say is this: echoing song, we have a definitive answer to your question now.

Echoing song quoted Einstein as he was discussing the magnitude of the angle of deflection of starlight passing the sun, “It may be added that, according to the theory, half of this deflection is produced by the Newtonian field of attraction of the sun, and the other half by the geometrical modification ('curvature') of space caused by the sun”. The space and time components of spacetime exert equal effects on the starlight. So consider each separately as pure space and pure time. Well, the pure time component reduces mathematically to Newton's exact equation, term for term, so that it makes perfect sense for Einstein to have referred to it as a Newtonian field of attraction. Did Einstein know about the derivation at the time he made this statement? I have no idea, but I'm sure he knew intuitively that it must exist.

Vaya con Dios, Mentz114.

 

[Mentz114]

overzealous,

the vitriol was intended for your friend echoing_song, but you sort of got caught in the blast since you seem to be acting as his emanuensis right now.

My remark about 'stirring up doubt ...' is based on a careful reading of ES's posts. A lot of genuine students, either self studiers or people on courses come here for help ( including me ) and they ask certain kinds of questions, and respond to answers in a certain manner. Usually a reference to a text or a brief discussion takes care of it.

There are other poster who fit a different profile. They always proclaim often that they are ignorant of details and want to learn. They then cherry-pick from the answers they are given, demanding clarification and emphasizing any perceived disparities in those answers. By all means, obvious contradictions should be challenged but the smallest thing will be jumped on. They will reject references that they consider 'too technical', even though their questions may be fully answered there. They often let slip something that indicates they have an agenda. Finally, they might in extreme cases issue a rallying call to other 'dissidents'.

Is there anybody out there who shares my problem with the curvature of time, or agrees with my way of reconciling things (in an earlier post)? To a hypothetical Silent Majority in cyberspace sympathetic to my position—it takes just seconds to register and express your views.

But possibly the most damning behaviour is declaring lack of expertise and then saying things like

blah-blah...Therefore, to speak of such inertial motion as due to the curvature of time is superficially true but deeply misleading. I believe these paragraphs put it into the proper perspective.

The agenda emerges pretty soon in this case

Maybe I'm on a senseless, quixotic quest; ...

No ! You've got a problem with unifying space and time - which is the very basis of SR and GR and you're arrogant enough to think you've got a strong point. At the same time saying you don't have the necessary technical skills.

So what happened to the earnest seeker after truth ? Did they go away and study, and learn the fundamentals of relativity ? No we get an extended philosophical discussion of little or no value. ES actually states that he doesn't see why space and time should be treated in an equal way - which is something you shouldn't get away with in a relativity forum.

Now, you might say this is nothing to get angry about. But it's an insult to all the people who did slog for years, pushing their personal boundaries to understand the maths.

You and your friends should get some good textbooks and do some studying.

 

[neopolitan]

Mentz,

I have had a closer look at the posts by echoing_song and overzealous and I strongly suspect they are the same person. It would explain why overzealous reacted to something said about echoing_song.

I take back what I said about you being aggressive, since it does appear that there is some form of coordinated campaign here.

My evidence:

<snip>
What impels me? I have no “professional” relationship with relativity, nor will I ever—at no time will I have to deftly manipulate Ricci tensors like a juggler does bowling pins, and though I admire both skills, I aspire to neither.

<snip>
with 'the curvature of space' reserved for esoterica like precession.

<snip>
Good questions, intelligent comments, shrewd analysis often comes from those without years of formal training. And I must say that my being this lone 'voice crying in the wilderness' on this issue is getting PRETTY DARNED ANNOYING. I'm realizing that I make a rotten John the Baptist.

<snip>
The idea that I want, to quote you, “to stir up doubt and dissent” about GR is an imputation of motive that would make my 'little round belly shake like a bowl full of jelly' from guffawing, if I didn't have high-carbon steel washboard abs.

Mentz114, let me say this very slowly, enunciating each syllable with Shakespearean-actor-like precision to avoid even the possibility of ambiguity, uncertainty, or misinterpretation: I love Einstein, I can't believe I'm privileged to share the same species designation with him.
<snip>

Note the similar flowerly turn of phrase and the similar use of punctuation. It makes me wonder if there is a product out there which can compare two texts and provide an estimate of how likely they were written by the same person. Maybe not 100% here, but I'd say it's pretty close to 90%.

I'm going to go with the greater likelihood that they are one person, and advise that one person that he/she has lost any credibility he/she might have had.

cheers,

neopolitan

 

[ccollins919]

Wow, I just found out what it is that bugs me about this and similar forums. The reason some of you contributors and some advisors have such a hard time with a little speculative thought, not to mention the occasional novel idea is that it's all still just an ego contest isn't it? Read the following quote: " you're arrogant enough to think you've got a strong point. At the same time saying you don't have the necessary technical skills.

So what happened to the earnest seeker after truth ? Did they go away and study, and learn the fundamentals of relativity ? No we get an extended philosophical discussion of little or no value. ES actually states that he doesn't see why space and time should be treated in an equal way - which is something you shouldn't get away with in a relativity forum.

Now, you might say this is nothing to get angry about. But it's an insult to all the people who did slog for years, pushing their personal boundaries to understand the maths.

You and your friends should get some good textbooks and do some studying.[/QUOTE] And there it is; a healthy dose of martyrdom. "I had to work hard, I had to push my boundaries..." I know, I know, it just doen't seem fair when someone has the audacity to voice an idea or even raise a question that might indicate that they haven't "put in the work" doesn't it? You know, I am a guy who has an eclectic range of tastes and sometimes I go slumming in the religious and mystical forums, and when I do I find the same kind of whiny, misanthropic self-pity along with the afore-mentioned battle cry of the martyr but at least there it is expected and therefore not so startling. Its seems incredible that someone could suggest that another person shouldn't get away with not seeing "..why space and time should be treated in an equal way.." Again, I say Wow. Are we all censors now? You might actually find less dogmatic adherence and aggression in those religion forums I spoke of. Come on! I was actually reprimanded yesterday for some supposed little infraction, and the tone was pretty malicious mind you, and I began to think about all the ways we, as human beings, hold our academic achievements out in front of us as both a shield against unwanted ideas and a weapon against those advancing them. You know, when it comes down to it, all people from all persuasions suffer from the same egoic needs as anyone else, and an education doesn't seem at all to be a guarantee against this: just the opposite as far as I can see. I was a prodigy who breezed through my classes, had my Doctoral thesis finished a year and a half in advance and goofed off a lot because I was quite frankly bored with the pace of the classes. But what I am not is cocky, arrogant, elitist, and I don't carry a cross on my back in the form of a degree that I pummel others with when they have the 'audacity' to exercise their imaginations a bit. In the religious forums, you get berated for individual thinking; in times not too long past you would be excommunicated. We have all studied and know intimately the details of the cutthroat world of scientific discoveries and the factions and division and all the times good men and women were ruined and had their reputations drug through the mud because their discoveries-not just their ideas but true, repeatable discoveries-were in conflict with the lifes work of a person or group of persons that may have had more clout, influence, or political connections. So, I ask all of you, especially those who hold their own self importance like a badge of honor, are you those that I speak of? Did I find you even here, in a forum none-the-less, the very definition of which is: an assembly or meeting place for the discussion of questions of public interest? ES, in the quote above, certainly deserves the right to not see why space and time should be treated in an equal way. It's the same as saying "I don't get it" or "I just don't see it" or even "I don't agree with it" Is that now something to kick one in the teeth for? I think the content of this forum is excellent and I commend those who sponsor and support it. Kudos to you. I hope you will not edit this post as it should be heard and may have a positive influence. Yes, I am an idealist. What will most likely happen is that people will just get angry. Humans can be depressingly predictable and their reactions tedious and typical. Oh, have I told you I also have a Psy.D degree? believe me, this post will not stay unless the managers are somewhat enlightened people who can see the benefit of this message to those who read it. Hope to see you all elswhere in the forum if I'm still around after this.

 

[matheinste]

Hello ccollins919.

I think much of what you say is correct. I am a beginner in relativity and I have seen from this forum that what you get out of it depends on your approach used in asking questions. I have made many statements which I now believe to be incorrect, and have asked "stupid" (my description) questions, and have not been subjected to any criticism or unpleasantness as a result of this. Some newcomers do not ask questions but make authoritative statements from an uninformed position. As an analogy, think of relativity as a book. Before you criticize it you should at least read it. When you have done so, then feel absolutely free to criticize and question it.

There is a big difference between realising that you do not understand and so wanting to find out, and not understanding and saying that, therefore, what you do not understand is wrong. Although of course it may be by default.


Matheinse.

 

[feynmann]

Subject: A Baffling Quote from Einstein, badly requiring explanation And yet in Einstein's own book, “Relativity”, in the appendix where he discusses “Experimental Confirmation of the General Theory of Relativity”, the following appears: He has just described the size of the angle of deflection of a ray of light passing the sun, and then says, “It may be added that, according to the theory, half of this deflection is produced by the Newtonian field of attraction of the sun, and the other half by the geometrical modification ('curvature') of space caused by the sun.”

Notice that he DOESN'T say that the result is entirely caused by the curvature of space and that it is twice what would be caused by SUPPOSED Newtonian attraction. The wording, which he had many decades and opportunities to revise before his death (but didn't in any of the subsequent editions), clearly indicates that gravitational attraction (presumably by a 'force') is half of the explanation. How can this be, in light of the unanimous view that GR casts aside all notions of anything but deformation of space?

And one further question: Is it true that the deflection is EXACTLY twice the Newtonian prediction? If so, why EXACTLY twice? And does this apply to starlight bent by the sun no matter how far away the starlight is from the sun, or only to starlight essentially grazing the sun as it passes? Obviously, in most situations, GR modifications of Newtonian predictions don't involve a doubling, but only an infinitesimal alteration (as with the GPS satellites data). I presume that if one were doing GPS locating on the sun, the modifications, while greater than on the earth, wouldn't approach a doubling. So why then in the case of passing starlight is it of such large magnitude?

I eagerly await enlightenment on all these points.

Strictly speaking, Newtonian gravity can't handle light properly. All moving objects climb out of gravitational field will lose speed and slow down. But light won't slow down when it climb out of the gravitational field. Einstein was right most of the time, but he did made a few mistake. e.g. he refer as "the biggest blunder of my life", regarding the universe expanding. He could have predicted it, as Dirac could have predicted the anti-particle of electron, but he shrank and thought the positive particle is proton, not positron

 

[feynmann]

“What is there to explain? Both models (inverse square law force and curved spacetime) are designed to yield a result that matches the same observations.”

If one theory (Newton's) has as its basis a mechanism totally different from that of the other theory, then it is indeed odd if they make predictions that are identical to double-digit decimal places, and it demands explanation, providing the following is true: Namely, if the remarkable accuracy of Newton is not due to the kind of thing that Ptolemy's geocentric theory did to make its predictions conform to reality--adding epicycles and deferents and all sorts of ad hoc absurdities that together created an utterly senseless, implausible, contrary-to-nature monstrosity. But, of course, Newton's gravitational equation is sleek and elegant, and logical too—the absolute antithesis of Ptolemy's theory, and other failed theories in the past that were arbitrarily twisted and tweaked until they matched observations.

That established, perhaps the explanation is nothing more than that GR is like some equations of SR, which, as velocities approach zero, literally reduce to the familiar Newtonian formulations. However, since I'm not conversant with Einstein's field equations (I'm just an interested amateur) I can't say if that is or isn't the case. But if Einstein's equations don't mathematically reduce to the Newton equation, but still yield nearly identical results in everyday situations, then that's really interesting. .

>> “What is there to explain? Both models (inverse square law force and curved spacetime) are designed to yield a result that matches the same observations.”

No, there is a big difference, it is not just "matches the same observations". In Newton's theory, time is absolute and universal, there is no speed of light as the limit, speed can be as fast as you can think of.