In the figure shown above,
CI is a plane board with a hole at its centre
and m is a mirror. The distance between M and CI
is maximum possible and is not less than a few
Kilometers. Mirror M is exactly parallel to
board CI. Here the complete apparatus is lying
in the North South direction.
Now when the light is
passed through O it should return on the same
path if the surface of the earth is stationary
with respect to the medium that contains the
universe. But, since the surface of the earth at
the equator is moving towards east we should not
expect the light to return on the same path and
let it strikes the board CI at P. We know that
the light or any fast moving particles take a
path which is always independent of the path of
the source. The surface of the earth has
tyravelled a distance OP by the time the light
has travelled from OM and MP.
Again, let the complete
apparatus is brought perpendicular to the
surface of the earth so that the board CI takes
the position of board C2. Board C2 is parallel
to the surface of the earth. Now if the light is
passed through O it should return on the same
path if the earth is not having any speed in the
horizontal plane including North and South. If
the earth is having some speed towards North
also the light should strike somewhere at Q.
Similarly keep the
apparatus in East West position i.e.,
perpendicular to the first position. Board CI
will take the position of board C3. Again see
the position of returning beam of light and let
it strikes at R. In figure II O'P', O'Q' and O'R'
are parallel and equal to OP, OQ and OR. From
O'P', O'Q' and O'R' a cuboid is completed as
shown. O' is joined with its opposite angle at
T. The vector TO' will give us the true speed of
the surface of earth without associating it with
any other heavenly object. Since the figure II
of cuboid is a three dimension figure, O' T
(blue colour line ) is not representing
the actual dimension and direction of the
earth's speed as the figure is drawn on a two
dimensional page.
Practically it would be
very difficult to perform such type of
experiment due to three reasons. Firstly, the
displacement of the returning beam of light will
be too small for precise measurement. Secondly,
it will not be almost possible to make the
mirror M exactly parallel to the board CI by
geometrical means ( without using any device
that require lens or light ). Thirdly, because
of its size of few kilometers.
In fact we can reduce the
distance between mirror and board by using
mirror in place of board too to allow multiple
reflections for the same beam of light.
