Gravitational Lensing : Eddington Experiment

Yes to his credit he did.
You on the other hand have totally lacked any intestinal fortitude and being able to admit your own many atrocious errors, and ignorance.
But this forum takes that now for granted.

 

Log in or Sign up to hide all adverts.

The local spacetime curvature, over the Planck length, is zero. It's an infinitesimal, flat, over large local proper frame areas in the weak field and over areas in the strong field which get smaller as you approach r=0. These large areas can be shown to be flat. The local proper frame is flat spacetime. Physbang has been asking some crank to show that isn't mathematically true. To no avail.

 

Log in or Sign up to hide all adverts.

The path through the local proper frame is straight. The path calculated from remote frame dependent coordinates is a global path which sums the infinitesimal local curvature over the entire global path. Velocity doesn't have anything to do with that. Too much. I get it you're making that prediction using your hidden Newtonian manifold brimming with ether particles. Wow the bowling ball explanation. Roll it slower and and it's path is curved. Who is the amateur?

 

Log in or Sign up to hide all adverts.

Idiot wind. To understand concept of infinitesimal like dx and ds one needs to have a formal knowledge of calculus which you do not possess. GL is operative at cosmic ranges and due to curved spacetime and talking of local infinitesimal flatness in the context is shear stupidity. Try proving flatness near BH singularity in local frame ? You will learn something.

 

Dear TG
You said...

The conjoin reading of both the above posts, an attempt to brag about education, false bravado about surprise and reference to 'notes' certainly shows that Xels.1947 copy paste was not as innocent as he is claiming.....anyways i will drop it here, since he has apologised to the forum.

My dear fellow you make assumptions too often that obscure the truth.
Firstly I posted the links because I thought you would find them interesting. Did you read any of them. They all related to GR and so I thought you would find them helpful.

My reference to not making notes and spoiling the ending was my attempt at humour reflecting my cheerful attitude such is the context of my post.

My mistake was my fault I had a friend at my door (we play chess) and I posted in haste but I absolutely reject your suggestion of any evil intent upon my part.

My surprise for you was not an attempt at anything sinister as you propose.

My surprise for you is this..
My education and profession was in law initially and later I owned a real estate office.

My surprise for you was the irony that as a high school student I presented a much better than average aptitude for science (always came first in science at school) and then followed a career in law and real estate.

Now is that not a surprise to you.

Now please tell me how admitting to a background in law on a science forum could be seen in any way at all boastful.

You seem like a nice enough chap but please becareful jumping to conclusions with little knowledge of the situation.. what ever that situation. Dont interpret that as preaching or talking down to you as jumping to hasty conclusions is a mistake many humans make.
There we go a post with no content and not on topic but I felt compeled to present a context that would inform you better.

 

And neither do you, so what's your point?

Please Register or Log in to view the hidden image!

Plus you have no evidence or references to support what you claim.
Gravitational lensing is not imagined...it is a fact, indicating curved spacetime and aligning with what GR says.
So once again, which part of accepted 21st century cosmology do you imagone you are invalidating now?

 

http://arxiv.org/pdf/1412.7521v2.pdf

ABSTRACT:
Clusters of galaxies are expected to gravitationally lens the cosmic microwave background (CMB) and thereby generate a distinct signal in the CMB on arcminute scales. Measurements of this effect can be used to constrain the masses of galaxy clusters with CMB data alone. Here we present a measurement of lensing of the CMB by galaxy clusters using data from the South Pole Telescope (SPT). We develop a maximum likelihood approach to extract the CMB cluster lensing signal and validate the method on mock data. We quantify the effects on our analysis of several potential sources of systematic error and find that they generally act to reduce the best-fit cluster mass. It is estimated that this bias to lower cluster mass is roughly 0.85σ in units of the statistical error bar, although this estimate should be viewed as an upper limit. We apply our maximum likelihood technique to 513 clusters selected via their SZ signatures in SPT data, and rule out the null hypothesis of no lensing at 3.1σ. The lensing-derived mass estimate for the full cluster sample is consistent with that inferred from the SZ flux: M200,lens = 0.83+0.38 −0.37 M200,SZ (68% C.L., statistical error only).

 

Have you understood what's my claim ?

 

And it used Netwonian gravity in order to make the prediction. How do you think gravity got involved?

Sure. I give Einstein's book "Foundations of the General Theory of Relativity". Or you could look at a newer book, like Schutz' "A first course in General Relativity".

At least now you have quite lying and you admit that your whole point in this thread is that there are no straight lines in GR.

Of course, you are missing the whole point of the Eddington observation: to compare the effects of the presence of the sun compared to the absence of the sun (when there would be no mass-energy there and thus there would not be curvature).

See, you don't understand the observation in the slightest!

So now you are half-way between your two positions.

I am still fixated on the idea that physics is not a priori in the epistemological sense. I now believe that you learned to change your tune so that you used a correct use of a priori. I am still fixated that any calculation done in 1911 was done without GR and thus any gravitational calculation done at that time would be done with Newtonian mechanics (or some derivation).

I remain fixated on the truth.

I remain awaiting your proof that there are no straight lines in GR, or in curved spacetime, or in whatever position you happen to hold from one part of your posts to another.

 

Is it that Mathematics of GR/Spacetime also does not support spacetime curvature in the "weak gravitational field", atleast infinitesimally( in the range of 'dx', where 'dx' is nonzero but very close to zero) ?

 

Is the 'gravitational waves' detected so far?

 

The spacetime used in GR is a manifold, essentially a set of infinitesimal SR spacetimes stitched together. So no curvature for infinitesimal distances, kinda.

Really, there is little use to speak of Plank lengths, yet. There can, in theory, be curvature over any finite distance, but the Plank length is a somewhat arbitrary distance that is small enough to currently escape the accuracy of our applications.

 

Atleast infinitesimal curvature should be there mathematically; if spacetime curvature is causing infinitesimal movement of a nonzero mass in the weak gravitational field.

 

You have no claim. How many times do you need to be told that.

 

I'll correct that: You have an illegitimate claim, but absolutely no evidence to support it.

 

No it predicts that IS the local spacetime curvature throughout the universe. It predicts the universe geometry is flat spacetime over large areas. The local proper frame is an invariant. That's where direct measurements of spacetime events are empirically conducted. That's the prediction for the local proper frame. The invariant frame. The frame which predicts larger spacetime curvature is the frame dependent remote coordinates. For the Schwarzschild spacetime geometry this is the remote bookkeeper coordinates which are essentially a calculation which sum the local curvature over the entire path. These calculated remote geodesics are very useful for making falsifiable predictions such as the dying pulse train [read about that]. A key to helping you understand the difference is understanding what invariant and frame dependent means in gravitational physics. If you want to hear more we could do a simple thought experiment which illustrates how small the local spacetime curvature is in the local proper frame and how large the tangent space area is in the weak field. Proper is another term we use for invariant in relativistic physics. The GPS experiment is a wonderful illustration. A good illustration would be how long it took us to find out that local spacetime curvature exists. Even somebody as brilliant as Newton never suspected it. How could they since everything look straights and you'd have to draw a straight line over an astronomical unit to even have a chance to measure a deviation between the beginning and end of the line. It's why folks have a hard time reckoning this could be true. The reason why EInsteins predicts gravity is local phenomena.

 

The God, it appears to me that your query pertains to whether or not the light path should or would be straight or geodesic(curved)?
Am I correct in that ?
If I am correct then it seems to me that the simplest answer is : The Path of Light is only being Curved or Bent while it is in the area of influence of the distorted or bent geodesic of whatever Mass is causing said Lensing. Once the area of influence is exited, any affected light will then resume a Straight Light Path.

The following Links are to some fairly decent articles/papers that should help you to better understand Gravitational Lensing :
- http://planet.racine.ra.it/testi/Dis/98-14b.htm
- http://www.pa.msu.edu/~abdo/GravitationalLensing.pdf
- http://odessa.phy.sdsmt.edu/~lcorwin/PHYS792DM_Spring2014/PHYS792Spring_DM_W3_1.pdf
- and from the Cornell University Search (Below) - https://ia700408.us.archive.org/11/items/cu31924012311530/cu31924012311530.pdf

I believe that these queries have been addressed, and do not seem to be of prime concern to you.

The God, as you must have surmised by your time on this Forum, very few of the most prolific Posters actually possess any extensive Academic credentials. It seems that many are Pop Science/Internet Educated (if that is an acceptable education!!??) only.
If some Members do not understand a query or cannot supply the answer, they seem to , at times, prefer to find fault with the Member positing the query...instead of simply stating that they do not understand or cannot answer the question.

The God, if you Honestly are truly interested in Learning and fully understanding the areas that this Thread is concerning, than I recommend that you begin by searching the on-line Libraries of any of a multitude of the Major universities.

For instance Cornell University has this Link : https://archive.org/details/cornell , where you can search its Archives.
Simply by typing (without the quotation marks, of course!) " Arthur Eddington " into the search box you can get access to the following .pdf (FOR FREE!!) : https://ia700408.us.archive.org/11/items/cu31924012311530/cu31924012311530.pdf


If you want to actually LEARN more than just regurgitated "pop science"...

 

Thanks for posting the Cornel Library link. The endowment was very interesting. Eddington does the preface. Very nice. BTW this is a good way to think about geodesic paths in relativity. Geodesic paths are natural free fall paths that follow the principal of extremal aging. Extremal can be either maximum or minimum. The geodesic paths for particles with mass, fermions, follows the path which is maximum and the null geodesic for light follows the minimum path. Neither of these have anything to do with being curved. This is a simple illustration. Take your bowling ball and flashlight to the 30 meter diving platform. Drop the bowling ball first. What path do you expect to see? Shine the flashlight over the same path the bowling ball covered. What do you expect to see? Which path took the extremal maximum and which path took the extremal minimum? Now take your experimental setup, LOL, and put it in your freefalling black hole probe and do the same experiment. What do you expect to see? See=observe for this imaginary experiment. No trick questions intended. Just an attempt to illustrate something you already intuitively know

 

Thanks for some good links dmoe,

Please Register or Log in to view the hidden image!

but I really doubt it will make any difference to the divine one.
In essence what the crank methodology is, is that if any link refutes their nonsense, then it is derided as 'pop science" an easy way out.

Please Register or Log in to view the hidden image!

In actual fact my friend, he has also many times dismissed university sites, and if you were up to date with his carryings on, you would have recognised that.
But again, thanks for some nice links.

Please Register or Log in to view the hidden image!

 

In summing, gravitational lensing is an observed fact as detailed by my many reputable links and arXiv papers.
There simple is no problem that exists, except of course withing the troubled mines of those afflicted with delusions of grandeur or some other anti science phobia, and cranks in general.........
Gravitational Lensing is an observed fact
The path of the light from the emitter to the observer, is dictated by curved spacetime or geodesics.
The eye interprets that curved geodesic path as a straight line and gives an apparent position different from the true position.

Please Register or Log in to view the hidden image!

Worth again posting the simplistic illustration that even primary children would understand.

Please Register or Log in to view the hidden image!