Declan Traill BSc
Interferometer Experiment trying to detect Anisotropy in the speed of light through the Earth's reference frame.
1310nm DFB Laser source
Optics box with NIR camera and USB cable
Optics Box - opened up, showing optics elements
NIR camera, NPBS cube, orthogonal PM fibers and X/Z Translation tables for alignment
Theoretical Calculations for the expected fringe shift with rotation angle of the interferometer.
Orthogonal interferometer arms - wooden structure
Interferometer arms, each wound with 15 turns (10m) of PM optical fiber.
Interferometer with inline 1x2 coupler and polarizer connected to PM fiber arms.
The full interferometer setup mounted on a rotating table, with laser source and battery connected and fibers from orthogonal arms connected to the closed optics box.
The first detection results imaged by the NIR camera. The fringes move in one direction, then pause and move in the other direction, as the orthogonal arms are rotated slowly in one direction, then pause and rotate in the other direction. The fact that the interference fringes move at all during rotation indicates that there is an anisotropy in the speed of light in the Earth's reference frame (that is moving through the Aether at ~486km/sec).
Correction!! : These initial result turned out to be in error as it was discovered that there was mechanical strain on two optic fiber connectors whilst rotating the interferometer. This caused a much greater effect (more fringe shifts) than was expected or modeled (as you can see in the above videos). The following video (below) was made after securing the two fiber connectors to prevent the mechanical strain. The number of fringe shifts during rotation decreased significantly after this change.
Expected fringe shift (Y-axis) over a full rotation (angle on X-axis)
The second detection results imaged by the NIR camera. The fringes move in one direction, then pause and move in the other direction, as the orthogonal arms are rotated slowly over about 100 degrees in one direction. The modeling shows there there is an expected fringe shift of around 2 fringes in each direction over this rotation interval. The video appears to show this. The fact that the interference fringes move at all during rotation indicates that there is an anisotropy in the speed of light in the Earth's reference frame (that has been found by other experiments to be moving through the Aether at ~486km/sec).
Expected fringe shift (Y-axis) over the approximate range of angles (225° to 325°) that the interferometer was turned during the above video clip. The modeling has been done for an Aether wind speed of 420km/sec which seems to match the observations here, better than the 486km/sec number (which would have a peak number of fringes of around 3 rather than 2).
Caution!! : These secondary results may be in error as there are still fringe shifts occurring due to movement of the rotating table and USB cable connected to the optical box, so it is difficult to prevent unwanted fringe shifts due to these factors and see just the effect due to rotational motion.
I took some further measures to reduce unwanted movement of the interferometer and cables (which can cause interference fringe shifts) and performed another run of the experiment, this time rotating the interferometer from an angle of 270° through to 360°.
The following graph shows the expected fringe shift, from the model, over this range of angles, if the optic-fibre-mode interferometer is subject to differing light travel times in the two orthogonal arms of the interferometer (as a gas-mode interferometer is). Also shown is the captured video clip of the interference fringe during this rotation. It is clear that NO fringe shift occurred due to the rotation.
Small Title
The modelling for this latest run of the rotating optic fiber interferometer experiment.
It is quite possible that there is no fringe shift due to rotation, despite the modeling indicating that there should be. This may be due to an effect that only occurs in single-mode optical fibers and would normally result in a fringe shift in a gas-mode interferometer. Please read evidence of this effect being seen in a similar experiment, here. See section 4.1 on page 16:
A New Light-Speed Anisotropy Experiment: Absolute Motion
and Gravitational Waves Detected
Reginald T. Cahill
Additional Note:
In light of my new findings about light propagation in various types of interferometers and cable types, I have fully modeled Cahill's "Flinders University Gravity Wave Detector" (see pages 15-24 in his paper. The link to the paper is above this box). I find that the maximum time difference that his detector would be capable of recording, for an Aether wind speed of 486km/sec would be ~0.01 ps (Picoseconds), which is a lot less that the reported change of 55 ps. What is more, this maximum time difference is the difference between the SUM of the two cable times, between a North/South and East/West orientation of the detector, not simply the difference in times between the two cable arms. The simple difference between cable arms is always exactly zero! Cahill seems to assume that because there is no difference in the travel times in the orthogonal arms of a single-mode optic fiber interferometer, that the travel times in opposite directions in such a fiber would be the same (i.e. the light would travel at c/n isotropically) - but this is invalid, as light signals are known to exhibit Fresnel Dragging and Sagnac type effects in single-mode optic fibers, so the one-way-speed-of-light times in such fiber would be different in different directions. I think Cahill's mathematical model is incorrect. I have posted a link to my modeling of his detector, incorporating everything that I have learned, on the right side of this box.
My accurate modelling of Cahill's Flinders University Gravity Wave Detector when orientated in a North/South configuration (aligned with the Aether wind)..
My accurate modelling of Cahill's Flinders University Gravity Wave Detector when in its circular calibration configuration.
Michelson-Morley and Miller (Mt Wilson) accurate modelling.
This is a diagram the depicts how the light signal travels in the interferometer arm that is perpendicular to the direction of motion through the Aether. This is applicable for gas-mode interferometers such as that used by Michelson-Morley and Miller (Mt Wilson) - (see the link to here to my paper that fully explains their results by my model) - but seems not to be the case for single-mode fiber interferometers such as used in this experiment and that conducted by Cahill his paper titled 'A New Light-Speed Anisotropy Experiment: Absolute Motion and Gravitational Waves Detected" (see link to the paper above).
Note:
Interestingly, trying to detect light speed anisotropy using single-mode Polarization Maintaining (PM) optic fibres in the interferometer arms (or other solid media such as glass) proves to be impossible and no light timing dependence on direction is observed. At first this seems odd as the Relativistic effect on the inertial mass of the molecules comprising the optical medium must surely still exist – so why is there no birefringence and detected anisotropy?
The reason why light behaves differently in single-mode optical fibre than it does in a gas-mode interferometer (or in a coaxial cable or other type of electrical conductor, where light speed anisotropy can also be observed) is that in a gaseous medium and in coaxial/electrical cables the masses that are set into oscillation by the passing Electromagnetic waves are not bonded into a lattice and subject to inter-molecular forces holding them in place, but act as single, individual molecules in space (i.e. as a molecular gas or free electrons, which act in a similar way to a gas).
In Lorentz’s paper that introduces and discusses Lorentz-Fitzgerald length-contraction and the differing inertial mass depending on direction (longitudinal or transverse) due to motion, he states: “…we must add the equations of motion for the ions themselves. In establishing these, we have to take into account, not only the electric forces, but also all other forces acting on the ions.” Thus, in single-mode fibres (or solid glass for example) the forces on the molecules are subject to the additional inter-molecular forces described by Lorentz, such that the forces in the direction of motion increase, along with (and in the same proportion as) the increased inertial mass in the longitudinal direction. Thus, the period of oscillation of the medium molecules' component charges due to the passing light waves remains the same in different directions. Thus, no birefringence due to Relativistic motion and no light propagation timing change is observed between orthogonal directions, despite the different inertial mass in these different directions.
It is for this reason that there are many published papers and experiments claiming that light speed isotropy has been proven to correct to many decimal places of accuracy - in those experiments the light’s speed is still anisotropic, but the timing in each of the two orthogonal directions is identical, due to the nature of the experimental design used, making the light’s propagation speed appear to be isotropic. The type of optical medium used in the experiment is crucial in determining if light speed anisotropy is detected or not. There are also other factors in the design of the experiment that can mask the anisotropy, such as the incidence of injection locking, especially when resonators and counter-propagating light beams are employed, where small changes in frequency of Electromagnetic waves (such as would be expected in anisotropy detection) are suppressed.
To detect the anisotropy requires that the optical medium in the optical path of the arms of the interferometer comprises discrete particles which have mass (molecules, atoms, or fundamental charged particles such as electrons) which are free to move and not bonded to their neighbouring particles in the medium. These particles must have charged components to them that are set into oscillation by passing Electromagnetic waves, causing the medium to have a refractive index greater than 1 (that of a vacuum).