The Sagnac Effect demonstrates that when light traveling at c hits a mirror that is moving away from the point
The Sagnac effect is observed when coherent light travels around a closed loop in opposite directions and the phases
of the two signals are compared at a detector. At the source and detector, a half-silvered mirror is usually employed so
that half of the source's transmission travels one way around the device and half the other way, with both beams ending
up at the same detector again, as in the simplified Sagnac apparatus in a) and b) below.
The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encounteredThe experiment doesn't prove the "existence of the aether," it just proves that the motion of an object can be
in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer. A beam of
light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the
two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the
position of the interference fringes, are shifted according to the angular velocity of the apparatus. In other words, when the
interferometer is at rest with respect to a nonrotating frame, the light takes the same amount of time to traverse the ring in either
direction. However, when the interferometer system is spun, one beam of light has a longer path to travel than the other in order
to complete one circuit of the mechanical frame, and so takes longer, resulting in a phase difference between the two beams. This
arrangement is also called a Sagnac interferometer. Georges Sagnac set up this experiment to prove the existence of the aether
that Einstein's theory of special relativity had discarded.
"Around-the-World Relativistic Sagnac Experiment" https://science.sciencemag.org/content/228/4695/69
Sagnac effect in an off-center rotating ring frame of reference https://iopscience.iop.org/article/10.1088/0143-0807/38/1/015301/pdf
The speed of laser light pulses launched from Earth and returned by a retro-reflector on the Moon was calculated from precision
round-trip time-of-flight measurements and modeled distances. The measured speed of light (c) in the moving observer’s rest frame
was found to exceed the canonical value c = 299,792,458 m/s by 200±10 m/s, just the speed of the observatory along the line-of-sight
due to the rotation of the Earth during the measurements. This result is a first-order violation of local Lorentz invariance; the speed
of light seems to depend on the motion of the observer after all, as in classical wave theory, which implies that a preferred reference
frame exists for the propagation of light. However, the present experiment cannot identify the physical system to which such a preferred
frame might be tied.
Source: Daniel Y. Gezari, Lunar Laser Ranging Test of the Invariance of c, arxiv.org (2010) https://arxiv.org/abs/0912.3934https://www.iers.org/SharedDocs/Publikationen/EN/IERS/Publications/tn/TechnNote34/tn34_097.pdf?__blob=publicationFile&v=1
Using the CCIR clock synchronization algorithm light speed was found to be c-v eastward and c+v westward in the frame of the rotating Earth.
Source: Stephan J. G. Gift, Faster west than east: The GPS invalidates Special Relativity, 20th Natural Philosophy Alliance Proceedings By David de Hilster, (2013, Vol. 10, pages 87 - 91) Lulu
From Eqs. (7) and (13), it follows that successful GPS operation demands that light travel faster west than eastSee also "The GPS and the constant velocity of light" by Paul Marmet (2000) http://www.newtonphysics.on.ca/illusion/
relative to the surface of the Earth. In particular the accurate operation of the synchronized clocks and range
equation of the GPS demonstrates that a light signal sent eastward travels at speed c minus the rotational speed of
the Earth v at that latitude, giving c - v as presented in Eq. (7). The accurate operation of the synchronized
clocks and range equation of the GPS also demonstrates that a signal sent westward travels at speed c plus the
rotational speed of the Earth v at that latitude giving c + v as presented in Eq. (13).
These speeds are exactly the east-west light speeds c +/- v found in independent investigations using GPS
Source: A simple demonstration of one-way light speed anisotropy using Global Positioning System (GPS) technology by Stephan R. G. Gift http://www.rxiv.org/pdf/1110.0037v1.pdf
Relativistic effects can be classified into three categories:
• Time Dilation. A transported clock, in this case on the satellite, runs
more slowly than one at rest on the Earth, in this case, the receiver clock.
This effect is solely a function of the satellite velocity.
• Blueshift Effect. The transported clock runs faster than the one on the
Earth. This effect is solely a function of the satellite altitude. [Time runs faster at satellite altitude than on earth]
• Sagnac Effect. The transported clock runs more slowly or faster than
the one on the Earth. This effect depends on the relative position of the
satellite and the terrestrial meridian of the receiver.
Source: Handbook of Satellite Orbits, by Michel Capderou, page 717
The information below is copied from: https://en.wikipedia.org/wiki/R%C3%B8mer's_determination_of_the_speed_of_light
Io is the innermost of the four moons of Jupiter discovered by Galileo in January 1610. Rømer and Cassini refer to it as the
"first satellite of Jupiter". It orbits Jupiter once every 42½ hours, and the plane of its orbit is very close to the plane of Jupiter's
orbit around the sun. This means that it passes some of each orbit in the shadow of Jupiter – an eclipse.
Viewed from the Earth, an eclipse of Io is seen in one of two ways.
- Io suddenly disappears, as it moves into the shadow of Jupiter. This is termed an immersion.
- Io suddenly reappears, as it moves out of the shadow of Jupiter. This is called an emergence.
From the Earth, it is not possible to view both the immersion and the emergence for the same eclipse of Io, because one or the
other will be hidden (occulted) by Jupiter itself. At the point of opposition (point H in the diagram below), both the immersion
and the emergence would be hidden by Jupiter.
For about four months after the opposition of Jupiter (from L to K in the diagram below), it is possible to view emergences of Io
from its eclipses, while for about four months before the opposition (from F to G), it is possible to view immersions of Io into
Jupiter's shadow. For about five or six months of the year, around the point of conjunction, it is impossible to observe the eclipses
of Io at all because Jupiter is too close (in the sky) to the sun. Even during the periods before and after opposition, not all of the
eclipses of Io can be observed from a given location on the Earth's surface: some eclipses will occur during the daytime for a given
location, while other eclipses will occur while Jupiter is below the horizon (hidden by the Earth itself).
The key phenomenon that Rømer observed was that the time elapsed between eclipses was not constant. Rather, it varied slightly at
different times of year. Since he was fairly confident that the orbital period of Io was not actually changing, he deduced that this was
an observational effect. The orbital paths of Earth and Jupiter being available to him, he noticed that periods in which Earth
and Jupiter were moving away from each other always corresponded to a longer interval between eclipses. Conversely, the
times when Earth and Jupiter were moving closer together were always accompanied by a decrease in the eclipse interval.
This, Rømer reasoned, could be satisfactorily explained if light possessed a finite speed, which he went on to calculate.
The outcome of the experiment was that the angular velocity of the Earth as measured by astronomy was confirmed to within
measuring accuracy. The ring interferometer of the Michelson-Gale experiment was not calibrated by comparison with an outside
reference (which was not possible, because the setup was fixed to the Earth). From its design it could be deduced where the central
interference fringe ought to be if there would be zero shift. The measured shift was 230 parts in 1000, with an accuracy of 5 parts
in 1000. The predicted shift was 237 parts in 1000. According to Michelson/Gale, the experiment is compatible with both the idea
of a stationary ether and special relativity.
Paper #1: http://adsabs.harvard.edu/full/1925ApJ....61..137M The Effect of the Earth's Rotation on the Velocity of Light - Part I
Paper #2: http://adsabs.harvard.edu/full/1925ApJ....61..140M The Effect of the Earth's Rotation on the Velocity of Light - Part II
The Kennedy–Thorndike experiment, first conducted in 1932 by Roy J. Kennedy and Edward M. Thorndike, is a modified form
of the Michelson–Morley experimental procedure, testing special relativity. The modification is to make one arm of the classical
Michelson–Morley (MM) apparatus shorter than the other one. While the Michelson–Morley experiment showed that the speed of
light is independent of the orientation of the apparatus, the Kennedy–Thorndike experiment showed that it is also independent of
the velocity of the apparatus in different inertial frames. It also served as a test to indirectly verify time dilation – while the negative
result of the Michelson–Morley experiment can be explained by length contraction alone, the negative result of the Kennedy–Thorndike
experiment requires time dilation in addition to length contraction to explain why no phase shifts will be detected while the Earth moves
around the Sun. The first direct confirmation of time dilation was achieved by the Ives–Stilwell experiment. Combining the results of
those three experiments, the complete Lorentz transformation can be derived.