There are two kinds of
Einstein’s theory of relativity. The first theory is special relativity
announced in the year 1905 with the famous equation of E = mc2, that describes the propagation of matter and light at high speeds.
The
second theory, general relativity, was announced in 1915. This theory was born
stimulated by the new fact just realized later on by Einstein that his theory
on Special Relativity was found to be inconsistent with the gravity theory of
Newton, declaring that the space objects
pull to each others with the force whose
magnitude is determined by distance between the said objects.
His
hypothesis in theory on special relativity that the light velocity is the
highest speed in this universe is in controversy with the gravity of Newton.
The velocity of force attracting to each others among objects at the space, for
example the attracting force of the moon
causing the change in short time in the form of movement of sea tide on earth
has the meaning that the gravity effect spreads at the boundless speed, not at
the light velocity or lower.
At his
theory on general relativity, Einstein declared a new law on gravity, stating that
gravity was not a force as commonly known at the Newton’s gravity theory, but a
part of inertia.. His gravity law illustrated the object behaviour at the
gravity field, for instance the planets, not in the sense of ‘the
attracting forcer’ but only in the sense of
the crossing track being
taken. For Einstein, gravity is a part of inertia. The movement of stars and
planets originates from their inertia derivation, and the crossing track taken
is determined by the space metrical nature, or more precisely the continuous
space-time..
“ Einstein’s Law of Gravitation contains
nothing about force. It describes the
behaviour of objects in a gravitational
field – the planets, for example – not in terms of ‘ attraction ‘ but simply in
terms of the paths they follow. To
Einstein, gravitation is simple part of inertia; the movement of the stars and the planets
arise from their inherent inertia; and
the courses they follow are determined by the metric properties of space – or,
more properly speaking, the metric
properties of the space-time continuum “
(Lincoln
Barnett, The Universe and Dr.Einstein,
London, June 1949, page 72 ).
At his
theory on general relativity, Einstein concluded that the light just as other
material objects, moved in curve
if gravity field of an object was massive. Einstein suggested that his
hypothesis could be tested to
observe the crossing track of the
star light at gravity field of the sun. Due
to the fact that the stars are not visible at day time, there is only one
chance when the sun and the stars can be seen together at the sky, and that is
the time when there is a solar eclipse.
He suggested that
the photo taken to the stars at the time when the sun was dark during the solar
eclipse was compared to the photo of the same stars taken at other time / at night time. According to his hypothesis,
the star light visible around the sun would be bent inwards, toward the sun at
the time when passing through the gravity field of the sun, so that the picture
of the stars would be visible for the observers on earth shifting outwards from
their actual position in the sky. Einstein calculated the level of their deviation and predicted that for the stars
observed being the closest to the sun, their deviation was about 1.75 second
arc.
The proving method of a theory as
suggested by Einstein was recorded at the book ‘The Universe and Dr. Einstein’ written by Lincoln Barnett,
published for the first time in London in June 1949. The Preface of this book
was written by Albert Einstein himself.
“ From these purely theoretical
considerations Einstein concluded that light, like any material object, travels
in a curve when passing through the gravitational field of a massive body. He suggested that his theory could be put to
test by observing the path of starlight in the gravitational field of the sun. Since the stars are invisible by day, there
is only one occasion when sun and stars can be seen together in the sky, and
that is during an eclipse.
Eintein
proposed, therefore, that photographs be taken of the stars immediately
bordering the darkened face of the sun during an eclipse and compared with photographs
of those same stars made at another time.
According to his theory, the light from the stars surrounding the sun
should be bent inward, toward the sun, in traversing the sun’s gravitational
field; hence the images of these stars should appear to observer on earth to be
shifted outward from their usual positions in the sky.
Einstein
calculated the degree of deflection that should be observed and predicted that
for the stars closest to the sun the deviation would be about 1.75 seconds of
an arc.
Since he staked his whole General
theory of Relativity on this test, men of science throughout the world
anxiously awaited the findings of expeditions which journeyed to equatorial
regions to photograph the eclipse of May 29, 1919. When their pictures were developed and
examined, the deflection of the starlight in the gravitational field of the sun
was found to average 1.64 seconds – a figure as close to perfect agreement with
Einstein’s prediction as the accuracy of instruments allowed. “ ( Lincoln
Barnett, The Universe and Dr.Einstein,
London, Victor Gollanez LTD, First Published June 1949, Preface by Albert
Einstein, page 78-79 ).
The proving method
as suggested by Einstein was carried out by a team of English scientists led by Arthur Stanley Eddington.
Based on data from
the Royal Astronomical Society, Arthur Eddington aimed to the group of Hyade stars from the city of Oxford in England at the nights in the months
of January and February 1919. After
that, Eddington together with his team left for Principe Island in West of
Africa, and aimed to the Hyade stars during the solar eclipse on the date of
May 29, 1919 at the city of Roca Sundy.
In the month of May
1919 the weather in Principe was not favourable because it was cloudy, and so
was the time before the eclipse. However, Eddington succeeded in taking the
photo of the solar eclipse taking place for 6 minutes 30 seconds. And the
calculation output on light deviation by Arthur Eddington was 1.62 second arc,
close to the Einstein’s calculation output of 1.75 second arc.
The proving method
for hypothesis as suggested by Einstein as the theory founder should not be
able to be carried out, considering the fact that in scientific exposure in
astronomy, the instant observation applies. It means, all calculations to
determine the ‘true position’ and the
‘apparent position’ of a certain star
at the sky is only applicable at a certain time and at a certain place on which
such observation is performed.
The observation on a
star conducted twice from the places with different geographical positions will
result the different height and azimuth of the star. The height and azimuth of
a star indicates the position of the star at the time when the observation is
performed. The height and azimuth of a star changes every time due to the daily
movement of the said space objects. Therefore, the proving method as conducted
by Arthur Eddington, should not be able
to be performed. Moreover, the observation / photo taking for the stars
were performed twice with sufficiently long different interval of time.
Below is an
illustration picture commonly used to explain ‘light deviation’ at the sun gravity field.
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