Gravitational Lensing : Eddington Experiment

Discussion in 'Astronomy, Exobiology, & Cosmology' started by The God, Nov 29, 2015.

  1. paddoboy Valued Senior Member

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    You need to read properly. I'm not disputing or arguing any point on the Sun's corona and any lensing effect, I'm trying to get you to understand that gravitational lensing is caused by any massive object, and need not be a star.
    When you understand what I said at post 58 we'll continue.
    [Or is this just your usual "white Knight effort to support a fellow pseudo lover]

    http://scienceblogs.com/startswithabang/2011/04/20/how-gravitational-lensing-show/

    http://www.astro.gla.ac.uk/~martin/outreach/lensing.html

    https://en.wikipedia.org/wiki/Einstein_Cross
     
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  3. The God Valued Senior Member

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    Origin;

    Reference to this fig geometry was made as early as my second post. I am well aware of the prevalent explanation of lensing in GR, but I get a feeling that you are putting in efforts to avoid the point raised by me.

    I will try once again..

    1. Take two arbitrary points A & B. The least mathematical path between them is an Euclidiean straightline joining them. In case of the flat spacetime this will be the path followed by the light.

    2. In case of presence of gravitational field, the spacetime will not be flat and it will be curved, then the path traversed by the light to cover A & B will be curved and it will not be the straightline. That means even the light will have to have a kind of projectile trajectory (as an analogy), but it will not be true projectile as there is no acceleration involved, this being the natural path for light to follow. Straightline between A & B is meaningless here because no object not even light can traverse that.

    3. There is nothing preferred. Straightlines or Arc Lines, none have any kind of preference. Then why do we extrapolate in straightlines? Simply because on Earth (in the weak Gravity) the geodesics are straightlines. So our extrapolation is on geodesics only, not that there is something sacrosanct about straightlines.

    4. In case of extreme Gravity, arc lines are the geodesics, and the light follows that path, so as a corollary our extension or extrapolation should be on the arc lines (geodesics only), why on straightlines, when they are seemingly meaningless? Thats the point. If you see the geometry of GR lensing picture, then it violates the principle of existence of geodesics and preferentiality, why must it be extended in a straightline to get the image, when around the lensing star we have only curved spacetime?

    Lets transport a big Cube (with sharp straight edges) on the surface of the Neutron Star, assuming that Neutron Star has extreme Gravity and appreciable curvature is present, now can you please analyse how an observer will see the cube from a distance?
     
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  5. paddoboy Valued Senior Member

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    And you believe after more than a 100 years and much validation and research, you have found an anomaly?
    If that were the case you would not be here as I have explained many times.
    No new theory or invalidation of GR will ever be forthcoming and originating from any science forum or any unqualified lay person.






    Firstly no assumption needed with regards to extreme gravity and spacetime curvature around a Neutron star...take it as given, per gravitational collapse and GR.
    Secondly any cube on the surface of a Neutron star would be quickly flattened due to the extremes of gravity.
     
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  7. origin Trump is the best argument against a democracy. Valued Senior Member

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    The straight line is showing the apparent position of the star not the actual position of the star. It really isn't difficult.
     
  8. paddoboy Valued Senior Member

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    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.
    The fact that this is so obvious is totally kindergarten stuff and illustrates how religious agendas and other medical problems, can have such an illusory effect on some, in their vain efforts to misinterpret and fabricate non existing problems.

    http://content.time.com/time/health/article/0,8599,2104225,00.html

    http://www.ncbi.nlm.nih.gov/pubmed/17773357

    https://en.wikipedia.org/wiki/Optical_Gravitational_Lensing_Experiment

    https://vela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/DE/didac.html

    http://www.einstein-online.info/spotlights/grav_lensing_history
     
  9. tashja Registered Senior Member

    Messages:
    715
    Interesting thought experiment, God. Like Paddo, I would imagine an object so close to the surface of a neutron star would get crushed. However, I get where you're coming from, so I reached out to an expert:

     
  10. The God Valued Senior Member

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    Thanks, Tashja.....You are extremely resourceful.

    The professor has explained the lensing. I have no dispute with the lensing aspect, it is well observed and the Geometry shown is perfect. The point raised by me is different; Does this 'valid explanation' confirm curved spacetime or Gravitational Newtonian kind of deflection with the flat spacetime in background? I am of the opinion it confirms Newtonian (barring the error of half in Newtonian, thats the different issue) with the flat spacetime as background.

    My argument is..

    1. The image will not form if the light is not deviated from the natural path.
    2. There is no preference for the straightline over the arc lines
    3. Extrapolation / Extension of lights (in ray Diagrams) can only be made on the path of light, not on any arbitrary straight or curved lines.


    Having said that, it is clear that in case of curved spacetime around a massive object, the natural path of of the light is geodesic only, so as per Sr#1 it is not a deviation, its THE natural path for light, and no image shall form if curved spacetime is a reality. But if we take flat spacetime and consider Newtonian deflection of light, then it is the deviation from the natural path of light and image shall form. To prove this was the purpose of NS thought experiment.


    Professor has confirmed that even on the surface of Neutron Star, we will see images, surely, we will, but that is only possible if background is flat spacetime. Again if the curved spacetime were to be the reality on the surface of NS then we may see a distorted object, but certainly not an image at some other place. In Newtonian we will see the image lifted as if object is lying inside water as explained by kind Professor.


    PS: Paddo and you are right, the cube may be crushed, but then the purpose was to understand the optics in extreme curved spacetime not the crushing power of Gravity. I could not have invoked BH because then light path is simply one way inside EH.
     
    Last edited: Dec 7, 2015
  11. brucep Valued Senior Member

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    4,098
    Nice post by Prof. Linder. The following is a derivation by Kevin Brown he calls refraction on relativity. Pretty nice. Notice that dphi=4M/r_o + 6pi-8(M/r)^2 + ........ Is equivalent to the GR weak field prediction dphi=4M/r in the first order. This is the prediction Professor Eddington carried to the first empirical test of GR. So the path of the light can be modeled using the refraction index. The way it's described, derived, from GR is the path of the light, null geodesic, follows the local spacetime curvature. The local path spacetime curvature in an infinitesimal, real small, but when it's accounted for by remote coordinates, observed from the HST, over the lights entire path the spacetime curvature near massive objects will be measured to be lensed. The term used.
    In the later pages of this Chapter 2 from Taylor and Wheeler Exploring Black Holes there's a discussion about the remote Schwarzschild bookkeeper coordinates. Actually page 2-34
    http://www.mathpages.com/rr/s8-04/8-04.htm
    Choose Chapter 2 Curving
    http://www.eftaylor.com/download.html#general_relativity
    Paddoboy linked a derivation of the Einstein Ring lensed equation but the way it's written just confused me. My problem.
    r_src=the physical position of the source of the light being lensed. r being the distance between the source and the observer which is r_obs.

    Einstein ring angle = [4Mr_src/r_obs(r_obs + r_src) ]^1/2
     
    Last edited: Dec 7, 2015
    paddoboy likes this.
  12. The God Valued Senior Member

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    The original point still remains unanswered..

    "In case of curved spacetime around a massive object, the natural path of of the light is geodesic only, so as per Fermat's principle it is not a deviation, its THE natural path for light, and no image shall form if curved spacetime is a reality. But if we take flat spacetime and consider Newtonian deflection of light, then it is the deviation from the natural path of light and image shall form."

    The Newtonian flat spacetime gives a deviation of 2M/r while the GR maths yields 4M/r, although GR calculations offer the correct angle, but that is the curvature of spacetime not the deviation. This suggests that we need to work out correction / improvization / New theory which is under flat spacetime as background.

    I know this is not going to happen with such objection in a forum like this, when great mainstream guys assent to ridiculous possibilities of meeting their now long dead great great grand fathers and also meeting their not yet born great great grand children. It calls for a complete paradigm shift and tremendous courage to re assess the GR predictions, scientists community will not be able to do it. Some public activist has to come forward and question the impossibility of time travel (meeting great great grand pa and great great grand kid) and move to the government and higher judiciary in the public interest for wastage of huge amounts of tax payers money in nonsensical research on these lines. I am sure scientists are accountable to public at large when they are funded by Public Money.

    The curved spacetime / Flat space background can simply be established by following observations also...

    1. Analogous experiment when an object is directly viewed in the curved spacetime, if there is no image its curved spacetime if there is image it is flat spacetime......'Fisheye Lense' gives an idea that there will not be image if it is curved spacetime. Like already discussed, on the Neutron Star surface an object will be visible as image lifted up in the sky in case of Flat Spacetime as background, but will be distorted (like seen from a fish eyelense) object view in case of curved spacetime.

    2. Around any massive object (Lensing Galaxy etc) there will be an envelop of bigger ring (may be ellipticall depending on the orientation and shape of galaxy), beyond this point light deviation will be almost nil due to Gravity of this massive Galaxy. The observation and analysis of observed objects inside this ring with respect to how many are real and how many are images will conclusively establish whether we have curved spacetime or flat space.
     
    Last edited: Dec 8, 2015
  13. paddoboy Valued Senior Member

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    21,225
    Thanks for your usual good work tashja and pass our thanks onto the Professor for confirming what most of us did know.
    In essence, no problem exists and GR stands as firm as it always has.
     
  14. paddoboy Valued Senior Member

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    There is no original point and never was....It's no more then a phony fabrication to supposedly add credibility to your past unsupported claims, the latest of which has been shifted to pseudoscience....I would have actually gone one rung lower.
    More pseudoscientific claims

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    Any modification. extension of GR is not going to happen on a science forum.
    You have been told this before, and I'll keep on telling you as long as you continue to post such outrageous claims and fabricated scenarios.

    While most normal folk on this forum do realize that time travel is not forbidden by GR, they are also smart enough to recognise another egotistical god driven rant as is yours above.
    Spacetime tells matter how to move; matter tells spacetime how to curve.
    John Wheeler:



    https://einstein.stanford.edu/
     
  15. paddoboy Valued Senior Member

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    21,225


    And as per other cranks like jcc and chinglu, constant theorist, the religious agenda is just as strong in this one.
     
  16. The God Valued Senior Member

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    To see science one needs to be educated...for linking anything with religion no knowledge/science is required. It is well established that you are an illiterate, so you will see religion or agenda everywhere.

    Now please stay away and do not crap on this thread, this is not for illiterates...
     
  17. paddoboy Valued Senior Member

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    Illiterate?
    It's your threads that have ended up in pseudoscience my friend.

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    And I'm certainly smart enough to have revealed two agendas re yourself now....the religious one and rajesh of course.
    Take it easy though, I know the truth hurts.
     
  18. The God Valued Senior Member

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    Stop playing your games, will you..
     
  19. paddoboy Valued Senior Member

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    I don't play games my friend. I'm just totally adverse to god botherers, those with delusions of grandeur, anti mainstream science nuts, or any combination thereof, that pretend to find fault with accepted mainstream science and/or GR.
    And I will most certainly remind these "would be's if they could be's", the reasons why they are wrong, and the logical extension that if any of them had anything of substance, [including yourself] you would not really be here.

    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!

     
  20. The God Valued Senior Member

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    You have not understood, I am not disputing this geometry or this explanation. This is correct. But this interpretation holds only in flat space not in curved spacetime. The curved geodesic path from source to our eye is the natural path of light if theory of curved spacetime is correct, in this case there shall not be any image or extension to apparent image. But in case of flat space and deviation due to Newtonian the light from source gets defelected and the path of light is not the natural path of light and image gets formed. Am I being religious in making this claim? Why don't you respond on this...
     
  21. paddoboy Valued Senior Member

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    Bullshit.
    You can pretend to your hearts content, but it hasn't fooled anyone.
    Religious agendas are used all the time, along with the general delusions of grandeur that goes with it, by cranks to try and invalidate science.
    In answer to your question, "Am I being religious in making this claim"? yes.
    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.

    The problem you envisage is non existent.
     
  22. paddoboy Valued Senior Member

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    The theory has been shown to be correct despite your continuing doubts.
    Bullshit and really to silly to even comment on.
     
  23. The God Valued Senior Member

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    But this is THE science......Image shall form only if there is any deviation from the natural path of light and the natural path is defined by Fermat's Principle......In curved spacetime, the curved path is the natural path, so it cannot be treated as deviation and no image shall form. But image is forming, that means it is not the curved spacetime but deflection of light due to Gravity in flat space background..So simple.

    In curved spacetime, Euclidean straightline is meaningless, because nothing can traverse that, not even light. [except possibly the radial lines.]. Resorting to flat Newtonian Space (or Minkowski Spacetime) to provide linear extrapolation is bad. This is not even approximation.
     

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