The same lie (the speed of light is constant in a gravitational field)
advanced by Stephen Hawking but he superimposes another lie by
claiming that the Michelson-Morley experiment confirmed the constancy
of the speed of light (originally, prior to introducing length
contraction, the ad hoc auxiliary hypothesis, the Michelson-Morley
experiment straightforwardly confirmed the variation of the speed of
light with the speed of the light source as predicted by Newton's
emission theory of light):

http://www.amazon.com/Brief-History-.../dp/0553380168
Stephen Hawking, "A Brief History of Time", Chapter 6:
"Under the theory that light is made up of waves, it was not clear how
it would respond to gravity. But if light is composed of particles,
one might expect them to be affected by gravity in the same way that
cannonballs, rockets, and planets are.....In fact, it is not really
consistent to treat light like cannonballs in Newtons theory of
gravity because the speed of light is fixed. (A cannonball fired
upward from the earth will be slowed down by gravity and will
eventually stop and fall back; a photon, however, must continue upward
at a constant speed...)"

http://www.hawking.org.uk/index.php?...64&It emid=66
Stephen Hawking: "Interestingly enough, Laplace himself wrote a paper
in 1799 on how some stars could have a gravitational field so strong
that light could not escape, but would be dragged back onto the star.
He even calculated that a star of the same density as the Sun, but two
hundred and fifty times the size, would have this property. But
although Laplace may not have realised it, the same idea had been put
forward 16 years earlier by a Cambridge man, John Mitchell, in a paper
in the Philosophical Transactions of the Royal Society. Both Mitchell
and Laplace thought of light as consisting of particles, rather like
cannon balls, that could be slowed down by gravity, and made to fall
back on the star. But a famous experiment, carried out by two
Americans, Michelson and Morley in 1887, showed that light always
travelled at a speed of one hundred and eighty six thousand miles a
second, no matter where it came from. How then could gravity slow down
light, and make it fall back."

Pentcho Valev 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 to http://www.amnh.org/education/resour...l/web/buybook/

http://www.amnh.org/education/resour...s_michell.html
"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."

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:

http://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/an...35_898-908.pdf
). 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