Re: Macros

Discussion in 'Digital Photography' started by dadiOH, Mar 16, 2013.

  1. dadiOH

    Martin Brown Guest

    On 02/05/2013 21:27, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 4/29/2013 8:57 AM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:
    >>>> On 4/22/2013 1:46 AM, Trevor wrote:

    >
    >>>>> Actually no, the light would be warped by the gravitational field of every
    >>>>> star system between the object and the lens! :)

    >
    >>>> If you want to get theoretical, the gravitational influence of randomly
    >>>> distributed objects might very well equalize each other. Therefore the
    >>>> rays would remain parallel.

    >
    >>> Actually, nope. It's the same as adding multiple random noise to
    >>> a signal or a random walk from a point.

    >
    >> vielleicht etwas zu tun <> etwas tun

    >
    > True but irrelevant.
    >
    > Getting theoretical: The theory how random influences add is
    > well established. That they equalize each other is about as
    > likely as that they completely add to each other, i.e. both
    > bowing the light in the identical direction. That's both not
    > "might very well", unless you "might very well" win a million
    > dollars in the lottery ten times in a row. So I bow to your
    > immense luck and admit I was wrong.
    >
    > -Wolfgang


    Trouble is that stars for the most part tend to be heavily concentrated
    in galaxies, cluster of galaxies and super clusters of clusters.

    The net result is that you can get strong lensing effects of very
    distant sources by galaxies or clusters between us and the source.
    Einstein rings were predicted long before they were observed.

    http://hubblesite.org/hubble_discov...nstein_rings_natures_gravitational_lenses.pdf

    Probably by far the prettiest one is the Hubble image of the horseshoe
    ring around LRG 3-757 (sorry about the unromantic name for the latter)

    http://nasa-image.blogspot.co.uk/2011/12/horseshoe-einstein-ring-from-hubble.html

    That said most of the light rays from distant sources to an exceedingly
    good approximation do remain parallel.

    --
    Regards,
    Martin Brown
     
    Martin Brown, May 8, 2013
    #21
    1. Advertising

  2. PeterN <> wrote:
    > On 5/6/2013 2:40 PM, Wolfgang Weisselberg wrote:

    [...]
    >>>>>> PeterN <> wrote:


    >>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>> rays would remain parallel.

    [...]

    >> So you're basically saying that the gravitational fields are
    >> ordered in such a way that photons from any random source stay
    >> parallel, at least in a sizeable number of cases.


    >> I'd like a single geometry designed by you where a bundle
    >> of parallel light rays from a single direction are bend by
    >> gravity sources in such a way that they remain exactly parallel.
    >> You can freely place the gravity sources.


    >> Kindly remember that any single gravity source will affect such
    >> a bundle of exactly parallel rays differently, depending on the
    >> mass of the gravity source and the (different!) distance from
    >> the individual ray to the gravity source. In other words:
    >> a bunch of parallel rays *will* be spread when it passes a
    >> gravity source ...


    >> Too hard?


    > I I precisely understood how gravitational forces interact, I doubt I
    > would waste time responding to you.


    If you precisely understood how gravitational forces
    (and matter and space) interacts, you'd probably on the list
    for the Nobel price.

    If you "merely"[1] had a working understanding of how
    gravitatonal forces act *and what that means* you'd be more
    careful about "in such a way that photons from any random
    source stay parallel", e.g. by making clear that they probably
    won't stay perfectly parallel. ('probably' only because I
    cannot guarantee that there can't be a setup where they *do*
    stay parallel.)

    -Wolfgang

    [1] not that that is something small in any way
     
    Wolfgang Weisselberg, May 8, 2013
    #22
    1. Advertising

  3. Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote:
    > On 02/05/2013 21:27, Wolfgang Weisselberg wrote:
    >> PeterN <> wrote:
    >>> On 4/29/2013 8:57 AM, Wolfgang Weisselberg wrote:
    >>>> PeterN <> wrote:
    >>>>> On 4/22/2013 1:46 AM, Trevor wrote:

    >>
    >>>>>> Actually no, the light would be warped by the gravitational field of every
    >>>>>> star system between the object and the lens! :)

    >>
    >>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>> distributed objects might very well equalize each other. Therefore the
    >>>>> rays would remain parallel.

    >>
    >>>> Actually, nope. It's the same as adding multiple random noise to
    >>>> a signal or a random walk from a point.

    >>
    >>> vielleicht etwas zu tun <> etwas tun

    >>
    >> True but irrelevant.
    >>
    >> Getting theoretical: The theory how random influences add is
    >> well established. That they equalize each other is about as
    >> likely as that they completely add to each other, i.e. both
    >> bowing the light in the identical direction. That's both not
    >> "might very well", unless you "might very well" win a million
    >> dollars in the lottery ten times in a row. So I bow to your
    >> immense luck and admit I was wrong.
    >>
    >> -Wolfgang


    > Trouble is that stars for the most part tend to be heavily concentrated
    > in galaxies, cluster of galaxies and super clusters of clusters.


    And that *keeps* the rays *parallel*?


    > The net result is that you can get strong lensing effects of very
    > distant sources by galaxies or clusters between us and the source.
    > Einstein rings were predicted long before they were observed.


    > http://hubblesite.org/hubble_discov...nstein_rings_natures_gravitational_lenses.pdf


    Yep, but the rays aren't parallel --- can't be, otherwise
    they must look like they came from the very same point (due
    to the distances involved).

    > That said most of the light rays from distant sources to an exceedingly
    > good approximation do remain parallel.


    Only for distances that are very short compared to the distance
    from where they come.

    But we were getting theoretical, not real-world 'close enough'.

    -Wolfgang
     
    Wolfgang Weisselberg, May 8, 2013
    #23
  4. dadiOH

    PeterN Guest

    On 5/8/2013 11:40 AM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 5/6/2013 2:40 PM, Wolfgang Weisselberg wrote:

    > [...]
    >>>>>>> PeterN <> wrote:

    >
    >>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>> rays would remain parallel.

    > [...]
    >
    >>> So you're basically saying that the gravitational fields are
    >>> ordered in such a way that photons from any random source stay
    >>> parallel, at least in a sizeable number of cases.

    >
    >>> I'd like a single geometry designed by you where a bundle
    >>> of parallel light rays from a single direction are bend by
    >>> gravity sources in such a way that they remain exactly parallel.
    >>> You can freely place the gravity sources.

    >
    >>> Kindly remember that any single gravity source will affect such
    >>> a bundle of exactly parallel rays differently, depending on the
    >>> mass of the gravity source and the (different!) distance from
    >>> the individual ray to the gravity source. In other words:
    >>> a bunch of parallel rays *will* be spread when it passes a
    >>> gravity source ...

    >
    >>> Too hard?

    >
    >> I I precisely understood how gravitational forces interact, I doubt I
    >> would waste time responding to you.

    >
    > If you precisely understood how gravitational forces
    > (and matter and space) interacts, you'd probably on the list
    > for the Nobel price.
    >
    > If you "merely"[1] had a working understanding of how
    > gravitatonal forces act *and what that means* you'd be more
    > careful about "in such a way that photons from any random
    > source stay parallel", e.g. by making clear that they probably
    > won't stay perfectly parallel. ('probably' only because I
    > cannot guarantee that there can't be a setup where they *do*
    > stay parallel.)
    >
    > -Wolfgang
    >
    > [1] not that that is something small in any way
    >


    But the origins of the gravitational are not random. You certainly are
    free to speculate what would happen if they were, but I would rather
    concentrate on the far less esoteric topic, of how to improve my images.

    --
    PeterN
     
    PeterN, May 9, 2013
    #24
  5. PeterN <> wrote:
    >>>>>>>> PeterN <> wrote:


    >>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>> rays would remain parallel.

    [...]
    > But the origins of the gravitational are not random. You certainly are
    > free to speculate what would happen if they were, but I would rather
    > concentrate on the far less esoteric topic, of how to improve my images.


    Did I get that right? You're basically saying that the
    objects are both random and not random?

    -Wolfgang
     
    Wolfgang Weisselberg, May 11, 2013
    #25
  6. dadiOH

    PeterN Guest

    On 5/11/2013 8:31 AM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >>>>>>>>> PeterN <> wrote:

    >
    >>>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>>> rays would remain parallel.

    > [...]
    >> But the origins of the gravitational are not random. You certainly are
    >> free to speculate what would happen if they were, but I would rather
    >> concentrate on the far less esoteric topic, of how to improve my images.

    >
    > Did I get that right? You're basically saying that the
    > objects are both random and not random?
    >


    Np Read carefully


    --
    PeterN
     
    PeterN, May 11, 2013
    #26
  7. PeterN <> wrote:
    > On 5/11/2013 8:31 AM, Wolfgang Weisselberg wrote:
    >> PeterN <> wrote:
    >>>>>>>>>> PeterN <> wrote:


    >>>>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>>>> rays would remain parallel.

    >> [...]
    >>> But the origins of the gravitational are not random. You certainly are
    >>> free to speculate what would happen if they were, but I would rather
    >>> concentrate on the far less esoteric topic, of how to improve my images.


    >> Did I get that right? You're basically saying that the
    >> objects are both random and not random?


    > Np Read carefully


    Please explain "the gravitational", then. I carefully read
    it as meaning "the gravitational influence/the gravitational
    objects", because *that* makes sense, while "the gravitational"
    does not, at least with my very limited knowledge of English ...

    -Wolfgang
     
    Wolfgang Weisselberg, May 13, 2013
    #27
  8. dadiOH

    PeterN Guest

    On 5/13/2013 3:41 PM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 5/11/2013 8:31 AM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:
    >>>>>>>>>>> PeterN <> wrote:

    >
    >>>>>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>>>>> rays would remain parallel.
    >>> [...]
    >>>> But the origins of the gravitational are not random. You certainly are
    >>>> free to speculate what would happen if they were, but I would rather
    >>>> concentrate on the far less esoteric topic, of how to improve my images.

    >
    >>> Did I get that right? You're basically saying that the
    >>> objects are both random and not random?

    >
    >> Np Read carefully

    >
    > Please explain "the gravitational", then. I carefully read
    > it as meaning "the gravitational influence/the gravitational
    > objects", because *that* makes sense, while "the gravitational"
    > does not, at least with my very limited knowledge of English ...
    >
    > -Wolfgang
    >


    Read again.
    IF the objects were truly random, ......
    Then I said but, the objects are not random. Nothing contradictory
    there. But yes I should have said the origins of the gravitational
    fields are not random. I hope this clarifies.

    BTW the authority for my statement is Einstein, and that is what I
    remember him telling me. Since I was only about 11 at the time, I might
    have misunderstood.

    --
    PeterN
     
    PeterN, May 14, 2013
    #28
  9. PeterN <> wrote:
    > On 5/13/2013 3:41 PM, Wolfgang Weisselberg wrote:
    >> PeterN <> wrote:
    >>> On 5/11/2013 8:31 AM, Wolfgang Weisselberg wrote:
    >>>> PeterN <> wrote:
    >>>>>>>>>>>> PeterN <> wrote:


    >>>>>>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>>>>>> rays would remain parallel.
    >>>> [...]
    >>>>> But the origins of the gravitational are not random. You certainly are
    >>>>> free to speculate what would happen if they were, but I would rather
    >>>>> concentrate on the far less esoteric topic, of how to improve my images.


    >>>> Did I get that right? You're basically saying that the
    >>>> objects are both random and not random?


    >>> Np Read carefully


    >> Please explain "the gravitational", then. I carefully read
    >> it as meaning "the gravitational influence/the gravitational
    >> objects", because *that* makes sense, while "the gravitational"
    >> does not, at least with my very limited knowledge of English ...


    >> -Wolfgang


    > Read again.
    > IF the objects were truly random, ......
    > Then I said but, the objects are not random.


    You started to talk about "theoretical" and "randomly
    distributed objects". Then you say "but they [the
    theoretical randomly distributed objects] are not random".

    > Nothing contradictory
    > there. But yes I should have said the origins of the gravitational
    > fields are not random. I hope this clarifies.


    Ok, the objects are not random, so your "If you want to get
    theoretical" claim has been abandoned as indefensible.

    So please construct a non-random arrangement of objects that
    do keep the rays in parallel as they pass through it. Have fun!

    > BTW the authority for my statement is Einstein, and that is what I
    > remember him telling me. Since I was only about 11 at the time, I might
    > have misunderstood.


    Which statement? That "randomly distributed objects might
    very well equalize each other"? That "Therefore the rays would
    remain parallel"? That "the origins of the gravitational are
    not random"? That you are not contradicting yourself?

    -Wolfgang
     
    Wolfgang Weisselberg, May 14, 2013
    #29
  10. dadiOH

    PeterN Guest

    On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 5/13/2013 3:41 PM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:
    >>>> On 5/11/2013 8:31 AM, Wolfgang Weisselberg wrote:
    >>>>> PeterN <> wrote:
    >>>>>>>>>>>>> PeterN <> wrote:

    >
    >>>>>>>>>>>>>> If you want to get theoretical, the gravitational influence of randomly
    >>>>>>>>>>>>>> distributed objects might very well equalize each other. Therefore the
    >>>>>>>>>>>>>> rays would remain parallel.
    >>>>> [...]
    >>>>>> But the origins of the gravitational are not random. You certainly are
    >>>>>> free to speculate what would happen if they were, but I would rather
    >>>>>> concentrate on the far less esoteric topic, of how to improve my images.

    >
    >>>>> Did I get that right? You're basically saying that the
    >>>>> objects are both random and not random?

    >
    >>>> Np Read carefully

    >
    >>> Please explain "the gravitational", then. I carefully read
    >>> it as meaning "the gravitational influence/the gravitational
    >>> objects", because *that* makes sense, while "the gravitational"
    >>> does not, at least with my very limited knowledge of English ...

    >
    >>> -Wolfgang

    >
    >> Read again.
    >> IF the objects were truly random, ......
    >> Then I said but, the objects are not random.

    >
    > You started to talk about "theoretical" and "randomly
    > distributed objects". Then you say "but they [the
    > theoretical randomly distributed objects] are not random".
    >
    >> Nothing contradictory
    >> there. But yes I should have said the origins of the gravitational
    >> fields are not random. I hope this clarifies.

    >
    > Ok, the objects are not random, so your "If you want to get
    > theoretical" claim has been abandoned as indefensible.
    >
    > So please construct a non-random arrangement of objects that
    > do keep the rays in parallel as they pass through it. Have fun!
    >
    >> BTW the authority for my statement is Einstein, and that is what I
    >> remember him telling me. Since I was only about 11 at the time, I might
    >> have misunderstood.

    >
    > Which statement? That "randomly distributed objects might
    > very well equalize each other"? That "Therefore the rays would
    > remain parallel"? That "the origins of the gravitational are
    > not random"? That you are not contradicting yourself?
    >
    > -Wolfgang
    >


    Not worth replying to

    --
    PeterN
     
    PeterN, May 15, 2013
    #30
  11. PeterN <> wrote:
    > On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >> PeterN <> wrote:


    [PeterN moved the goalposts and can't even tell us which
    statement he claimed he had heard from Einstein himself]

    > Not worth replying to


    Sour grapes, Peter? Very sour grapes, eh?

    -Wolfgang
     
    Wolfgang Weisselberg, May 16, 2013
    #31
  12. dadiOH

    PeterN Guest

    On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:

    >
    > [PeterN moved the goalposts and can't even tell us which
    > statement he claimed he had heard from Einstein himself]
    >
    >> Not worth replying to

    >
    > Sour grapes, Peter? Very sour grapes, eh?
    >
    > -Wolfgang
    >


    No just not replying to troll questions.

    --
    PeterN
     
    PeterN, May 18, 2013
    #32
  13. PeterN <> wrote:
    > On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    >> PeterN <> wrote:
    >>> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >>>> PeterN <> wrote:


    >> [PeterN moved the goalposts and can't even tell us which
    >> statement he claimed he had heard from Einstein himself]


    >>> Not worth replying to


    >> Sour grapes, Peter? Very sour grapes, eh?


    > No just not replying to troll questions.


    Yep, asking you what exactly Einstein told you is a troll
    question *and* an insult.

    But still, I'd like a configuration where gravity sources
    (carefully placed by you) do *not* influence parallel light
    rays to become non-parallel.

    -Wolfgang
     
    Wolfgang Weisselberg, May 20, 2013
    #33
  14. dadiOH

    J. Clarke Guest

    In article <>, ozcvgtt02
    @sneakemail.com says...
    >
    > PeterN <> wrote:
    > > On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    > >> PeterN <> wrote:
    > >>> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    > >>>> PeterN <> wrote:

    >
    > >> [PeterN moved the goalposts and can't even tell us which
    > >> statement he claimed he had heard from Einstein himself]

    >
    > >>> Not worth replying to

    >
    > >> Sour grapes, Peter? Very sour grapes, eh?

    >
    > > No just not replying to troll questions.

    >
    > Yep, asking you what exactly Einstein told you is a troll
    > question *and* an insult.
    >
    > But still, I'd like a configuration where gravity sources
    > (carefully placed by you) do *not* influence parallel light
    > rays to become non-parallel.


    Wolfgang, I really do not understand why you are harping on this ad-
    nauseum. If you think it has some real relevance to the issue of
    starlight being treated as parallel rays then do explain the relevance.
     
    J. Clarke, May 21, 2013
    #34
  15. dadiOH

    PeterN Guest

    On 5/20/2013 6:56 AM, Wolfgang Weisselberg wrote:
    > PeterN <> wrote:
    >> On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:
    >>>> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >>>>> PeterN <> wrote:

    >
    >>> [PeterN moved the goalposts and can't even tell us which
    >>> statement he claimed he had heard from Einstein himself]

    >
    >>>> Not worth replying to

    >
    >>> Sour grapes, Peter? Very sour grapes, eh?

    >
    >> No just not replying to troll questions.

    >
    > Yep, asking you what exactly Einstein told you is a troll
    > question *and* an insult.


    Go back and read. If you don't believe me, that is your problem.


    >
    > But still, I'd like a configuration where gravity sources
    > (carefully placed by you) do *not* influence parallel light
    > rays to become non-parallel.
    >


    I didn't say that in a random configuration that would be no influence.
    I said there could be offsetting influences. But we already went that
    route.


    --
    PeterN
     
    PeterN, May 21, 2013
    #35
  16. J. Clarke <> wrote:
    > In article <>, ozcvgtt02


    >> But still, I'd like a configuration where gravity sources
    >> (carefully placed by you) do *not* influence parallel light
    >> rays to become non-parallel.


    > Wolfgang, I really do not understand why you are harping on this ad-
    > nauseum. If you think it has some real relevance to the issue of
    > starlight being treated as parallel rays then do explain the relevance.


    Naah, it has no real relevance.

    Except when "you want to get theoretical" (PeterN's words),
    in that case the rays don't stay perfectly parallel except for
    a very few configurations (e.g. inside a perfect and hollow
    sphere). I had hoped PeterN would think about it or look it up
    (and maybe present such a configuration) and thereby understand
    that his claim of
    | If you want to get theoretical, the gravitational influence of randomly
    | distributed objects might very well equalize each other. Therefore the
    | rays would remain parallel.
    (PeterN in Message-ID:
    <51771a0b$0$10833$-secrets.com>)
    was wrong.

    Thinking about it: he probably knows it by now, he just
    *can't* admit that he was not completely right --- strictly
    theoretically, that is.
    You're right, I should let PeterN from the hook, he's digging
    so fast that one can't see very much any more from all dirt
    he's throwing up.

    -Wolfgang
     
    Wolfgang Weisselberg, May 22, 2013
    #36
  17. In rec.photo.digital.slr-systems Wolfgang Weisselberg <> wrote:
    > PeterN <> wrote:
    >> On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    >>> PeterN <> wrote:
    >>>> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >>>>> PeterN <> wrote:


    >>> [PeterN moved the goalposts and can't even tell us which
    >>> statement he claimed he had heard from Einstein himself]


    >>>> Not worth replying to


    >>> Sour grapes, Peter? Very sour grapes, eh?


    >> No just not replying to troll questions.


    > Yep, asking you what exactly Einstein told you is a troll
    > question *and* an insult.


    > But still, I'd like a configuration where gravity sources
    > (carefully placed by you) do *not* influence parallel light
    > rays to become non-parallel.


    Similar to the chromatic aberration problem in lens design. You can
    never get rid of it completely. But you can use carefully placed later
    chromatic aberration to undo most of an earlier introduced chromatic
    aberration. You can do the same kind of thing with gravitational
    bending of light ray bundles, especially when the rays are very narrow
    and the gravitational fields are large and distant, so minimising the
    non-linearity of the bending across the bundle.

    Perhaps a nearer example is the bending of light rays due to
    atmospheric thermals on a hot sunny day. Easily seen through a long
    lens as the wriggling of distant straight lines. Have you ever noticed
    that if you take a short enough exposure those wriggly straight lines
    are often both wriggly and sharp at the edges. In other words despite
    the thermal bending of the light rays they've maintained a close
    approximation to parallelism.

    --
    Chris Malcolm
     
    Chris Malcolm, May 22, 2013
    #37
  18. dadiOH

    Noons Guest

    On 21/05/2013 11:53 PM, J. Clarke wrote:

    >
    > Wolfgang, I really do not understand why you are harping on this ad-
    > nauseum. If you think it has some real relevance to the issue of
    > starlight being treated as parallel rays then do explain the relevance.
    >



    (muppet newsflash): it's called
    - wait for it -
    T-R-O-L-L-I-N-G
    (/muppet newsflash)
     
    Noons, May 23, 2013
    #38
  19. Chris Malcolm <> wrote:
    > In rec.photo.digital.slr-systems Wolfgang Weisselberg <> wrote:
    >> PeterN <> wrote:
    >>> On 5/16/2013 8:43 AM, Wolfgang Weisselberg wrote:
    >>>> PeterN <> wrote:
    >>>>> On 5/14/2013 5:35 PM, Wolfgang Weisselberg wrote:
    >>>>>> PeterN <> wrote:


    >>>> [PeterN moved the goalposts and can't even tell us which
    >>>> statement he claimed he had heard from Einstein himself]


    >>>>> Not worth replying to


    >>>> Sour grapes, Peter? Very sour grapes, eh?


    >>> No just not replying to troll questions.


    >> Yep, asking you what exactly Einstein told you is a troll
    >> question *and* an insult.


    >> But still, I'd like a configuration where gravity sources
    >> (carefully placed by you) do *not* influence parallel light
    >> rays to become non-parallel.


    > Similar to the chromatic aberration problem in lens design. You can
    > never get rid of it completely.


    Homogenous hollow sphere (as the only object). Whereever
    you are inside, the pull is identical in each direction.
    Therefore a Dyson sphere is inherently stable, but a ringworld
    would be unstable and needs active stabilization against the
    tiniest movements.

    > But you can use carefully placed later
    > chromatic aberration to undo most of an earlier introduced chromatic
    > aberration. You can do the same kind of thing with gravitational
    > bending of light ray bundles,


    Hod do you propose bending no-longer-parallel light rays back
    to being parallel again without having negative gravity?

    > especially when the rays are very narrow
    > and the gravitational fields are large and distant, so minimising the
    > non-linearity of the bending across the bundle.


    Yep, that's why it doesn't matter usually, but in theory it
    does.

    > Perhaps a nearer example is the bending of light rays due to
    > atmospheric thermals on a hot sunny day. Easily seen through a long
    > lens as the wriggling of distant straight lines. Have you ever noticed
    > that if you take a short enough exposure those wriggly straight lines
    > are often both wriggly and sharp at the edges. In other words despite
    > the thermal bending of the light rays they've maintained a close
    > approximation to parallelism.


    Air --- like the glass in our lenses --- can both concentrate
    and spread light rays. How do you do that with gravity?

    -Wolfgang
     
    Wolfgang Weisselberg, May 23, 2013
    #39
  20. dadiOH

    PeterN Guest

    On 5/22/2013 6:24 AM, Wolfgang Weisselberg wrote:
    > J. Clarke <> wrote:
    >> In article <>, ozcvgtt02

    >
    >>> But still, I'd like a configuration where gravity sources
    >>> (carefully placed by you) do *not* influence parallel light
    >>> rays to become non-parallel.

    >
    >> Wolfgang, I really do not understand why you are harping on this ad-
    >> nauseum. If you think it has some real relevance to the issue of
    >> starlight being treated as parallel rays then do explain the relevance.

    >
    > Naah, it has no real relevance.
    >
    > Except when "you want to get theoretical" (PeterN's words),
    > in that case the rays don't stay perfectly parallel except for
    > a very few configurations (e.g. inside a perfect and hollow
    > sphere). I had hoped PeterN would think about it or look it up
    > (and maybe present such a configuration) and thereby understand
    > that his claim of
    > | If you want to get theoretical, the gravitational influence of randomly
    > | distributed objects might very well equalize each other. Therefore the
    > | rays would remain parallel.
    > (PeterN in Message-ID:
    > <51771a0b$0$10833$-secrets.com>)
    > was wrong.
    >
    > Thinking about it: he probably knows it by now, he just
    > *can't* admit that he was not completely right --- strictly
    > theoretically, that is.
    > You're right, I should let PeterN from the hook, he's digging
    > so fast that one can't see very much any more from all dirt
    > he's throwing up.
    >
    > -Wolfgang
    >


    You simply refuse to understand what "random" means.

    --
    PeterN
     
    PeterN, May 23, 2013
    #40
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