Photon Propagation : Straightline or Helix ?

Discussion in 'Physics & Math' started by The God, May 12, 2016.

  1. Farsight Valued Senior Member

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    No, he wasn't lazy in his writings, and his text is clear to the layman.

    No, that's a popscience myth. Hence you will not be able to quote Einstein saying that. However I can quote this at you:

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    You're still dismissing Einstein in favour of your ersatz popscience misunderstanding of general relativity.

    Einstein said repeatedly that the speed of light varies with position. And he isn't the only one. See The Deflection and Delay of Light by Ned Wright and this PhysicsFAQ article by Don Koks:

    "Einstein talked about the speed of light changing in his new theory. In the English translation of his 1920 book "Relativity: the special and general theory" he wrote: "according to the general theory of relativity, the law of the constancy of the velocity [Einstein clearly means speed here, since velocity (a vector) is not in keeping with the rest of his sentence] of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [speed] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers."

    This is wrong I'm afraid. The ascending photon speeds up, because a gravitational field is a place where the speed of light is spatially variable.

    General relativity is, curved space is not.

    Yes. It contradicts Einstein in some important respects, and is wrong.

    You are kidding yourself. I'm the one who refers to Einstein, you're the one who dismisses him with popscience and handwaving platitudes such as "much progress has been made since".

    I'm way in advance of you on SR and GR, and nobody has shown that what I've said is incorrect, because I'm correct, because Einstein's correct. And by the way, it's Nobel, not Noble.
     
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  3. sweetpea Registered Senior Member

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    Rpenner , in this particular experiment, free fall of ball of test particles, is this where we see an example of curved space? Note, not only curved spacetime?
    This is from the Baez site...
    http://math.ucr.edu/home/baez/einstein/node9.html
    My bold.

    Are there other examples of curved space and not just spacetime ?
     
    Last edited by a moderator: May 27, 2016
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  5. paddoboy Valued Senior Member

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    And yet from your own link it says.......
    [Einstein clearly means speed here, since velocity (a vector) is not in keeping with the rest of his sentence]
    The only pop science I see is that you are trying to convince the world of something which contradicts all experimentations and that which is evident in this highly silly statement of yours.......
    in reply to my....
    So in effect you are "correcting" the accepted mainstream interpretation of how GR is viewed today

    Apologies for my slip up in spelling Nobel as Noble, but the essence of what I was trying to say stands.
    Your claims, as are your past claims are questionable at best and just plain wrong at worst and a misinterpretation of what others are trying to convey.
    Curved spacetime by its very nature means that a path from A to B is longer that that same path if it were flat. Light simply follows the curved path we call geodesics in that spacetime, and your continuous denial of that here and elsewhere is getting you nowhere except perhaps a reputation as a GR crank.
     
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  7. paddoboy Valued Senior Member

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    No he did not.....What the article you linked to said......
    http://www.astro.ucla.edu/~wright/deflection-delay.html
    "This Newtonian model also predicts that the gravitational attraction of the Sun will make light travel faster close to the Sun, so according to Newton the deflected light arrives before the undeflected light".

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    The above clearly shows that according to Einstein [GR] that light has a longer path to travel and therefor from a remote frame of reference, it's "speed" will seem to be slower, when in actual fact it has travelled further. Again please refer to a curved path and geodesics.
    This clearly shows that you are simply fabricating your nonsense to support your own ideas, as also you did claiming that Einstein "could not" be lazy in his writings.


    PS: Apologies again for my rather lazy style, but also from your article it says......
    http://www.astro.ucla.edu/~wright/deflection-delay.html
    Einstein predicts that light will be delayed instead of accelerated when passing close to the Sun. Notice in the figure above that the green light pulse arrives after the black light pulse.

    NB: Delayed [obviously because it has a longer distance to travel] not accelerated.
     
    Last edited: May 27, 2016
  8. arfa brane call me arf Valued Senior Member

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    On measurement of a tidal force:

    One experiment that can do this is possible in a free falling lab (aka Nasa's vomit comet). As the lab falls toward the centre of the earth, arrange a pair of test particles so they are horizontally separated. As the lab frame accelerates the two particles will move closer together and this displacement should be measurable. You could connect the two small weights to a strain gauge, or some device that can detect pressure between the two weights.

    The point being, the two horizontally displaced particles will move closer together, because both are following the shortest path (aka geodesic) towards the centre of gravity of the earth, and these paths deviate. This isn't hard to visualise if you draw a diagram of a circle with lines radiating out from the centre, clearly the lines are closer together near the centre than further away.
     
  9. The God Valued Senior Member

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    3,546
    Rpenner,

    You agreed with me that Paddoboy is equivocating. The only difference is, I used the word ‘ding dong’ for’ equivocation’. Then why infraction ?
     
  10. The God Valued Senior Member

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    3,546
    Rpenner

    I am sorry, but you have failed to educate people (those who are following you, I am not) regarding this straight-line question. Still people here like Paddoboys, Origins are not able to distinguish between euclidean straightline and spacetime straightline, and you, by putting complex maths here, have done no benefit to such people. I will demonstrate how you have miserably failed, even though your maths is faultless.

    1. Newton stated that things move forever in straight-line at constant velocity unless some external force acts on them….
    You allowed the misinterpretation of this statement by couple of posters. The emphasis of Newton was on constant velocity, not on straight-line as such, by this statement Newton was attempting to establish inertia and constancy of velocity in absence of force (non acceleration), he was not at all defining straight-line here. You failed to clarify this and allowed this nonsense to continue.

    You know very well that in Newtonian Mechanism an accelerated particle can move in a straight-line.

    2. You know very well that, in general, for public at large (all non GR guys), the concept of straight- line, curve, circle, ellipse, parabola etc, is related and associated with mathematical geometry in Euclidean space. In such geometry a straight-line between two points is a unique line joining two points with the least path. No physics play any kind of role here, none of these are associated with any physical stuff like force or acceleration…so associating force or acceleration with straight-line is bad and unwarranted.

    3. Moving on to curved spacetime, Einstein had a problem. Newton was heavily on his mind when he proposed GR. Einstein did not consider gravity as force, so if the gravity was not force then the change of speed of falling objects (free fall) or change in direction of motion of stellar objects (orbital motion), would have violated Newton. So Einstein used his brilliance to avoid possible objections, and he tweaked the straight-line definition…All free falling bodies will move in straight-line unless acted upon by force.

    There is a difference between Newton’s statement and Einstein statement…Newton had no intent to define straight-line, he had no intent to associate absence of force with straight-line, for him straight-line was unique connecting line between two points with least distance, but in case of Einstein now the straight-line got deceptively linked with the presence or absence of force.

    Moreover, please read the OP again, I am talking about motion in 3D space, while you are talking about 4D spacetime. I am talking about perception and reality, you are talking about maths and tweaked definitions.

    I will give you one more example, as per definition any curved segment (Path) on the earth surface shall be geodesic, whether you call it straight-line or not, I don’t care, but motion on this path by an object is not equivalent to free fall and hence it is not a straight-line…see How Paddoboy was pushing this, but you did not correct him.
    You remained mum on projectile motion also, we all know that the path covered by projectile (general) in space is parabola…who bothers if you call it straight-line in GR. This clearly establishes that use of term straight-line for such paths in space is bad. Geodesic would have been just fine.

    The summary, Rpenner, is Einstein made a mistake in paying too much attention to that Newton’s Inertia statement. He should have continued with his Geodesic word without bringing in straight-line in his definitions. This would have been far better. Another deliberate confusion in GR ?
     
    Last edited: May 28, 2016
  11. The God Valued Senior Member

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    Space is bent ?

    If it comes from you then its a matter of concern, you are a mathematician.

    even though this is tough to answer, what bends ? But one thing is for sure space does not bend.

    Just imagine, if space curves or bends, then will it depend on the initial condition of the object in motion ? For example a faster projectile will curve less and slower will curve more ? whatever bends, in the mind only, in the maths of spacetime only. Curving or curved motion profile of an object under gravity, does not mean that the space has bent.

    Let us not confuse the spacetime mapping with the absolute spatial motion of an object...
     
  12. expletives deleted Registered Senior Member

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    410
    rpenner:

    It is my understanding that the Least Action Principle was originally formulated based on observing real force presence/balance studies; and only later abstracted into a formalized mathematical/geometrical description of what was happening depending on the parameters of forces and directions (vectors and magnitudes etc) applying and varying (or not) over time. The motions of the test particle(s) would determine the measurement values over time and path of those parameters which were used in the abstrac mathematics/geometry analysis construct. Please correct me if I am wrong in that initial understanding. If I’m not wrong in that, then, on that understanding, I make the following responses to your points in turn.


    Unless you are espousing pre-existing Philosophical ‘Platonic Forms’ in universal "real space", then what you describe is again an abstract mathematical/geometrical ‘reduction’ of the observed real motions; along a path over time described by real particles; responding to the presence/balance of real forces acting in space and impinging upon the particle to produce the observed real path which exists and may be described in abstract mathematical/geometrical terminology based on an abstract 4-d “mathematical space”. The path exists only when a real particle traverses and so describes that path. That path (whterh geodesic or non-geodesic in character) does not exist until a particle actually traverses and so decribes it in “real space” in response to real forces present/balance in real space not "mathematical space". That is my understanding on this point.


    Abstract descriptions of space and time are not valid unless they represent actual particles, motions and forces. The abstractions may be descriptive but they do not ‘pre-exist’ in space and time like some Philisophical ‘Platonic Forms’ were alleged to ‘pre-exist’ irrepsective of particles and motions arising to actually manifest the real consequences and forms in real space and real traversed path lines of least action. That is my understanding on that point.


    May I ask: how does a choice of “length squared” (instead of “action”) change the real particle and forces dynamics which produce the “real space” (not “mathematical space”) path of least resistence consequences in any real situation, however described in abstract or real observation terms?


    Again, are you talking of a mathematically/geometrically “pre-described” Platonic Forms "Philosophical geodesic", or an actual observable “after the fact” geodesic labeled real space path traversed and described functionally in dynamics, irrespective of what Co-ordinate Time etc variables are applied before the event, in a mathematical/geometrical modeling of what is ‘expected’ having regard to the actual forces/balance ‘input’ to the abstract analysis/prediction? I cannot respond fully to this point until I have some further clarification from you on what you meant to convey in that point. Thanks.


    Can you edit your comment 5) please (I cannot parse what you mean here):

    “...as the straight lines where every corresponding to those..”

    I suspect a word/term was inadvertently omitted? Thanks.


    Yes, as I noted my understandig above on this aspect, in GR it is the motions according to gravitational influence(s) [or force(s), depending on what physical/abstract perspective one invokes to describe the dynamics/entities involved] which determine what path is traversed and so described as part of the ongoing event, irrespective of the mathematical/geometrical analytical ‘Platonic Forms’ invoked in analytical and descriptive constructs in theory as a convenient ‘generalization’ of what happens in the whole gamut of possible variable parameters in any case unders stady. That is again my understanding on that point.


    Yes, in an abstract construct such as you bring via your commentary based on abstract mathematical/geometrical perspective, that is consistent philosophically speaking. However, unless you can priovide the “real space” entities and fprces/parameters and paths possible in that real space, then an “infinite” network of “infinitesimal” points is only mathematical/geometrical description, not actual real path information from which the forces prsent/balance can be identified in fact not just in theory according to what is expected from that theory. In other words, the least action path is real; the geodesic path is an expected pre-existing form in abstraction which gives no real clue to what is actually ‘acting’ in “real space” dynamics fro wich the ‘geodesic concept/form’ is derived but not real in itself as some absolute and eternal ‘Platonic Form’ which the geodesic philosophy implies it is based on via some “mathematical space” only ‘existing’ in the mathematical formulation used. That is my understanding on that.


    Actually, you raise a very interesting point there, rpenner. In “real space” in an infinite universe there can only ever be transient and open paths, since all events lead to further events and oarticles and energy ‘bifurcate’ at every opportunity afforded by the dynmics in 3-d “real space” over time according to the motions and variations of energy floes involved over the infinite term. Only once we ‘split or limit’ those dynamics according to some domain boundaries imposed by observers, can we speak of ‘closed’ anything, including dynamics and paths (Ie, motions over time and number of particles involved). Do you get my meaning there? I have probably not expressed it very well.


    Yes, again, as I pointed out in my previous post where I alluded to the “least action path” perspective/analysis etc, I have always understood this from early on in my extensive thinking and long reading in this area. Thanks for confirming it so authoritatively like that, rpenner. And thanks too for your erudite response and clarifications of what you meant in your earlier discussions with others on these matters. I appreciate learned members' (you and certain others) responses much more than any responses (no matter how numerous and trivial) from the (demonstrably) least learned, who merely repeat the essence of the initial discussion rather than contribute anything that actually helps in clarifying the further implications arising in discussion which prompted my previous post in the first place. I look forward to visiting again in the near future to follow up any further responses from you or any other learned member. Thanks again, rpenner.
     
    Last edited: May 28, 2016
  13. Farsight Valued Senior Member

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    Wrong. Read what Ned Wright said: In a very real sense, the delay experienced by light passing a massive object is responsible for the deflection of the light. Light curves because the speed of light is slower near the massive object. Not because "it follows the curvature of spacetime".

    I'm not fabricating nonsense. Popscience quacks and charlatans are fabricating nonsense, and you slavishly follow them whilst dismissing Einstein and other bona-fide physicists:

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  14. Farsight Valued Senior Member

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    To get back on topic, photon propagation in gravity-free space is straightline, not helical. Check out Rod Nave's hyperphysics, where you can see this picture:

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    The direction of propagation is a straight line, but the "electric vector" is helical. That's because it's the production of two out-of-phase orthogonal waves. But neither wave is rotating in any way.
     
  15. paddoboy Valued Senior Member

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    If the whole world and mainstream academia are indulging in pop science nonsense and such then we have much to worry about.
    But of course like the many other alternative hypothesis pushers we have, you are ignoring the relevant data since Einstein, coupled with taking extracts out of context, misinterpreting and generally pushing nonsense, which sees you being the charlatan.
    You push much here and elsewhere Farsight including saying you have a TOE, and you have been banned also elsewhere for similar antics.
    The speed of light is certainly a constant and measuring it depends on one's frame of reference.
    Curved spacetime by its very nature means that anything following its path [including light] has a further distance to travel.

    https://en.wikipedia.org/wiki/Propagation_of_light_in_non-inertial_reference_frames
    The description of motion in relativity requires more than one concept of speed. Coordinate speed is the coordinate distance measured by the observer divided by the coordinate time of the observer. Proper speed is the local proper distance divided by the local proper time. For example, at the event horizon of a black hole the coordinate speed of light is zero, while the proper speed is c.[1] The coordinate speed of light (both instantaneous and average) is slowed in the presence of gravitational fields. The local instantaneous proper speed of light is always c.
     
  16. paddoboy Valued Senior Member

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    21,647
    https://einstein.stanford.edu/content/relativity/q411.html
    What is a space time continuum?

    In 1906, soon after Albert Einstein announced his special theory of relativity, his former college teacher in mathematics, Hermann Minkowski, developed a new scheme for thinking about space and time that emphasized its geometric qualities. In his famous quotation delivered at a public lecture on relativity, he announced that,

    "The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality."

    This new reality was that space and time, as physical constructs, have to be combined into a new mathematical/physical entity called 'space-time', because the equations of relativity show that both the space and time coordinates of any event must get mixed together by the mathematics, in order to accurately describe what we see. Because space consists of 3 dimensions, and time is 1-dimensional, space-time must, therefore, be a 4-dimensional object. It is believed to be a 'continuum' because so far as we know, there are no missing points in space or instants in time, and both can be subdivided without any apparent limit in size or duration. So, physicists now routinely consider our world to be embedded in this 4-dimensional Space-Time continuum, and all events, places, moments in history, actions and so on are described in terms of their location in Space-Time.

    Space-time does not evolve, it simply exists. When we examine a particular object from the stand point of its space-time representation, every particle is located along its world-line. This is a spaghetti-like line that stretches from the past to the future showing the spatial location of the particle at every instant in time. This world-line exists as a complete object which may be sliced here and there so that you can see where the particle is located in space at a particular instant. Once you determine the complete world line of a particle from the forces acting upon it, you have 'solved' for its complete history. This world-line does not change with time, but simply exists as a timeless object. Similarly, in general relativity, when you solve equations for the shape of space-time, this shape does not change in time, but exists as a complete timeless object. You can slice it here and there to examine what the geometry of space looks like at a particular instant. Examining consecutive slices in time will let you see whether, for example, the universe is expanding or not.
    """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
    But since many trolls are apt to write off any links contrary to their personal thoughts and beliefs as pop science, in more simple language, although spacetime may not be a physical entity, that in no way does not mean it is not real. Spacetime is a unified multi-dimensional continuum within which cosmologists and scientists in general, use to locate events and describe the relationships between them in terms of spatial coordinates and time. The concept of spacetime follows from the observation that the speed of light is invariant, i.e. it does not vary with the motion of the emitter or the observer. Spacetime allows a description of reality that is common for all observers in the universe, regardless of their relative motion. Intervals of space and time considered separately are not the same for all observers:In GR, gravitation is described in terms of the curvature/warping, twisting and waving of spacetime.
    All that at this stage has been confirmed beyond reasonable doubt, via many experiments, including GP-B and aLIGO.
     
    Last edited: May 29, 2016
  17. expletives deleted Registered Senior Member

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    paddoboy:

    Thankyou for again posting stuff all learned members in this field are already well aware of. You needn't have bothered. But since you have again cluttered a thread with personal animosities and prejudicial language against your perceived enemies whom you gratuitously (and in my case incorrectly) label "trolls", "god botherers" etc, seemingly at every opportunity, then I will reply to your above 'cut and paste' in the hope that you will be satisfied with the attention and reduce your compulsive need to clutter up some more, at least in this thread.

    In answer to the thrust and point of your cut and paste response, I note that your referenced excerpt admits that it is only their philosophical "view" of "space and time", and that their "space-time" construct is not supposed to represent an actual physically real "fact". In particular, their philosophical view/construct does not explain what "time" actually is when treating it in the philosophical manner of a real dimension.

    From my long reading and comprehension on this "time" aspect, it is self-evident in fact, that the "time" concept" is abstraction derived from observed, physically real motions and relativities between said motions of the observed matter and energy features whose dynamics are abstracted and only thereafter given mathematical/geometrical formulation and graphing "dimensions" in analytical construct such as "space-time" models (in which the only real physically observable and measurable dimension is spatial dimension lengths and directions; with "time dimension" being the abstracted relativities and variables of the measured motions within the spatial dimensions which test particles and features present in the observed and measured dynamical parameters involved).

    My question discussion with rpenner, a learned member (which you are demonstrably far from being anytime soon if your posting history is any guide), is predicated on that common understanding. Your posting a cut and paste re-iteration of what my discussion with learned members is aimed at clarifying, does in no way add anything useful to that end (in fact it detracts from that end by clutter and unnecessary personal and antagonistic comments and tone which you seem unable to resist injecting even in a discussion between learned members and myself which can do very well, and do better even, without your apparently insatiable compulsion to post clutter and cut and paste triviality and dogma which you apparently don't understand the full implications of in the context of the discussion you intrude upon between members wishing to concentrate on the scientific issues rather than your personal diversions and cluttering trivialities).

    Paddoboy, I have responded to you now in such a way, and in hopes, that you will note and take the hint about how derailing and detracting it is for others and myself to have to trawl through your usual voluminous streams of unnecessary and unhelpful cut and paste and dogmatic yet ill-comprehend opinions and assertions which do not advance the discussion at all. Can you resist temptation to intrude unnecessarily in future, at least in my discussions with learned members? I would prefer to hear from rpenner instead of you; not only because he is a learned member whom I can respect even if we disagree on something, but also because his contribution to and responses in our mutual discussion will make your own cut and paste and ill-comprehend posts totally unnecessary and just 'noise'. Thanking you in advance for your future kind co-operation in this matter, paddoboy.

    I will wait for rpenner or any other learned member to respond and advance this discussion I am having with rpenner. Thanks.
     
    Last edited: May 29, 2016
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  18. The God Valued Senior Member

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    The guy has copy pasted 'Tangent' definition.
    His penchant for mindless copy paste is unmatched.
    His desire to declare others (me on top of list) as trolls, god bothereres etc, is a part if his argument in all threads.
    His love for that Minkowski spacetime statement, forces him to copy paste that in every third thread.
    He feels that he is the torch bearer of mainstream, without even knowing what the mainstream is all about..
    I admonished him many a times on his mindless copy pastes, result : more copy pastes, more cluttering
     
  19. paddoboy Valued Senior Member

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    21,647
    And I have rightly admonished you on your silly claims and denials re 21st century cosmology, particularly the inane claims re GP-B and aLIGO being fraudulent: still you clutter and whinge when taken to task over your many errors.
     
  20. The God Valued Senior Member

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    You know Paddoboy, I do not make mistakes....
     
  21. paddoboy Valued Senior Member

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    21,647
    It does still seem to have escaped you though, and the ignorant claims that follow in your post support that.
    Spacetime is as real as a magnetic field or any other non physical entity, and that is supported by many professionals, although some do disagree.
    The only "philosophical"aspect is the personal definition of "real"
    PS; My cluttering as you put it, is necessary to at least help to explain the errors of our anti mainstream brigade.
    Let me ensure you also [I have ensured others of this fact] that no unsupported claims, or rewriting of 21st century cosmology, is going to make any difference with what mainstream academia accept, based on observational and experimental evidence.
     
  22. paddoboy Valued Senior Member

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    21,647
    That's why at least three threads of your's have been shifted to the fringes....
    And of course your delusions are your own problem...enjoy them

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  23. The God Valued Senior Member

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    So ? I will call that as a failed attempt. How does it help your point ?
    Quite sick you are Paddoboy !!
     

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