🚀 go-pugleaf

On Mar 7, 7:48 am, Pentcho Valev <pva...@yahoo.com> wrote:
> An excerpt from COSMIC HORIZONS: ASTRONOMY AT THE CUTTING EDGE, edited
> by Steven Soter and Neil deGrasse Tyson, a publication of the New
> Press. © 2000 American Museum of Natural History. To order the book,
> call 1-800-233-4830, or go tohttp://www.amnh.org/education/resources/rfl/web/buybook/
>
> http://www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/cs_...
> "Michell accepted Newton's theory that light consists of small
> material particles. He reasoned that such particles, emerging from the
> surface of a star, would have their speed reduced by the star's
> gravitational pull, just like projectiles fired upward from the Earth.
> (...) Michell got the right answer, although he was wrong about one
> point. We now know, from Einstein's relativity theory of 1905, that
> light moves through space at a constant speed, regardless of the local
> strength of gravity."

i agree, light, if massless, it just follows its path,
through "curved space", if existent, and knows
nothing about gravitation and such

but it must know something about diffraction,
because the space is felt with dust

>
> Needless to say, in 1905 Einstein did not say anything like "light
> moves through space at a constant speed, regardless of the local
> strength of gravity". Rather, from 1907 on, he claimed that, in a
> gravitational field, the speed of light is VARIABLE, not constant. In
> 1911 Einstein was explicitly using Newton's emission theory of light
> in order to show how the speed of light varies with the gravitational
> potential:
>
> ttp://www.physlink.com/Education/AskExperts/ae13.cfm
> "So, it is absolutely true that the speed of light is not constant in
> a gravitational field [which, by the equivalence principle, applies as
> well to accelerating (non-inertial) frames of reference]. If this were
> not so, there would be no bending of light by the gravitational field
> of stars....Indeed, this is exactly how Einstein did the calculation
> in: 'On the Influence of Gravitation on the Propagation of Light,'
> Annalen der Physik, 35, 1911. which predated the full formal
> development of general relativity by about four years. This paper is
> widely available in English. You can find a copy beginning on page 99
> of the Dover book 'The Principle of Relativity.' You will find in
> section 3 of that paper, Einstein's derivation of the (variable) speed
> of light in a gravitational potential, eqn (3). The result is,
> c' = c0 ( 1 + V / c^2 )
> where V is the gravitational potential relative to the point where the
> speed of light c0 is measured."
>
> http://www.blazelabs.com/f-g-gcont.asp
> "So, faced with this evidence most readers must be wondering why we
> learn about the importance of the constancy of speed of light. Did
> Einstein miss this? Sometimes I find out that what's written in our
> textbooks is just a biased version taken from the original work, so
> after searching within the original text of the theory of GR by
> Einstein, I found this quote: "In the second place our result shows
> that, according to the general theory of relativity, the law of the
> constancy of the velocity of light in vacuo, which constitutes one of
> the two fundamental assumptions in the special theory of relativity
> and to which we have already frequently referred, cannot claim any
> unlimited validity. A curvature of rays of light can only take place
> when the velocity of propagation of light varies with position. Now we
> might think that as a consequence of this, the special theory of
> relativity and with it the whole theory of relativity would be laid in
> the dust. But in reality this is not the case. We can only conclude
> that the special theory of relativity cannot claim an unlimited domain
> of validity ; its results hold only so long as we are able to
> disregard the influences of gravitational fields on the phenomena
> (e.g. of light)." - Albert Einstein (1879-1955) - The General Theory
> of Relativity: Chapter 22 - A Few Inferences from the General
> Principle of Relativity-. Today we find that since the Special Theory
> of Relativity unfortunately became part of the so called mainstream
> science, it is considered a sacrilege to even suggest that the speed
> of light be anything other than a constant. This is somewhat
> surprising since even Einstein himself suggested in a paper "On the
> Influence of Gravitation on the Propagation of Light," Annalen der
> Physik, 35, 1911, that the speed of light might vary with the
> gravitational potential. Indeed, the variation of the speed of light
> in a vacuum or space is explicitly shown in Einstein's calculation for
> the angle at which light should bend upon the influence of gravity.
> One can find his calculation in his paper. The result is c'=c(1+V/c^2)
> where V is the gravitational potential relative to the point where the
> measurement is taken. 1+V/c^2 is also known as the GRAVITATIONAL
> REDSHIFT FACTOR."
>
> In 1915 Einstein managed to get rid of Newton's emission theory of
> light by replacing the equation c'=c(1+V/c^2) with c'=c(1+2V/c^2),
> which is tantamount to replacing 2+2=4 with 2+2=5:
>
> http://www.mathpages.com/rr/s6-01/6-01.htm
> "In geometrical units we define c_0 = 1, so Einstein's 1911 formula
> can be written simply as c=1+phi. However, this formula for the speed
> of light (not to mention this whole approach to gravity) turned out to
> be incorrect, as Einstein realized during the years leading up to 1915
> and the completion of the general theory. In fact, the general theory
> of relativity doesn't give any equation for the speed of light at a
> particular location, because the effect of gravity cannot be
> represented by a simple scalar field of c values. Instead, the "speed
> of light" at a each point depends on the direction of the light ray
> through that point, as well as on the choice of coordinate systems, so
> we can't generally talk about the value of c at a given point in a non-
> vanishing gravitational field. However, if we consider just radial
> light rays near a spherically symmetrical (and non- rotating) mass,
> and if we agree to use a specific set of coordinates, namely those in
> which the metric coefficients are independent of t, then we can read a
> formula analogous to Einstein's 1911 formula directly from the
> Schwarzschild metric. (...) In the Newtonian limit the classical
> gravitational potential at a distance r from mass m is phi=-m/r, so if
> we let c_r = dr/dt denote the radial speed of light in Schwarzschild
> coordinates, we have c_r =1+2phi, which corresponds to Einstein's 1911
> equation, except that we have a factor of 2 instead of 1 on the
> potential term."
>
> http://www.speed-light.info/speed_of_light_variable.htm
> "Einstein wrote this paper in 1911 in German (download from:http://www.physik.uni-augsburg.de/annalen/history/einstein-papers/191...
> ). It predated the full formal development of general relativity by
> about four years. You can find an English translation of this paper in
> the Dover book 'The Principle of Relativity' beginning on page 99; you
> will find in section 3 of that paper Einstein's derivation of the
> variable speed of light in a gravitational potential, eqn (3). The
> result is: c'=c0(1+phi/c^2) where phi is the gravitational potential
> relative to the point where the speed of light co is measured......You
> can find a more sophisticated derivation later by Einstein (1955) from
> the full theory of general relativity in the weak field
> approximation....For the 1955 results but not in coordinates see page
> 93, eqn (6.28): c(r)=[1+2phi(r)/c^2]c. Namely the 1955 approximation
> shows a variation in km/sec twice as much as first predicted in
> 1911."
>
> http://www.online-literature.com/orwell/1984/
> George Orwell "1984": "In the end the Party would announce that two
> and two made five, and you would have to believe it. It was inevitable
> that they should make that claim sooner or later: the logic of their
> position demanded it. Not merely the validity of experience, but the
> very existence of external reality, was tacitly denied by their
> philosophy. The heresy of heresies was common sense. And what was
> terrifying was not that they would kill you for thinking otherwise,
> but that they might be right. For, after all, how do we know that two
> and two make four? Or that the force of gravity works? Or that the
> past is unchangeable? If both the past and the external world exist
> only in the mind, and if the mind itself is controllable what then?"
>
> Pentcho Valev
> pva...@yahoo.com