Hello all

As a primer (if you need) here are some sites:

http://www.fourmilab.ch/cship/aberration.html

http://en.wikipedia.org/wiki/Aberration_of_light

http://www.newtonphysics.on.ca/Aberration/Aberration.html

There are two ways to measure “aberration of light”. The first involves knowing the exact position of two objects/stars in space, A and B, and from the vector BA measure the angle that a telescope on B must be inclined to view A. The second involves changing the velocity of B and measuring the change in the inclination angle needed to view A. However the second method will only measure the “aberration of light” due to the change in B’s velocity.

Aberration of light is based on the fact that a photon travels in a straight line in space-time (space-time may be curved but the photon doesn't notice). The velocity of the emitter does not matter to the photon’s direction of travel (the photon does not travel sideways). The telescope is designed to magnify/collect photons that travel parallel to the optic axis of the telescope. The velocity of the telescope with respect to the photon is all that matters.

Absolute aberration of light can only be determined by the first method or if we had a way to measure the instantaneous change in aberration angle. Since light/photons travel in straight lines and is/are independent of the source then I will propose a method for discussion to measure absolute aberration of light via instantaneous change (or close to it) of the angle of aberration.

Take a long rotating cylinder with a laser at one end and a CCD photo detector at the other end. As the cylinder rotates the path of the laser on the CCD will change and will form a circle for the output of the CCD. The orientation of the rotating axis is then changed and the diameter of the output recorded. When the circle is at a maximum diameter then the axis of rotation is at right angle to the absolute linear velocity (Vc) of the cylinder through space. When the circle is at minimum diameter then the axis of rotation is parallel to Vc. The difference between the maximum/minimum diameters, the length of the cylinder, and the speed of light can be used to determine Vc.

Hello all

For a maximum "aberration of light" of one arc minute and using a 1/2 inch CCD the tube would need to be 21.8 ft long. A 5 million pixel CCD would give a resolution of approximately 0.05 arc seconds. A collimated laser beam through a pin hole should give a fine enough light source at a distance of 21.8 ft. The rotation of the cylinder can be less than the response time of the CCD. I believe the tube can be made shorter by using optic lenses.

Hi Montec,

http://math.ucr.edu/home/baez/physics/Rela...xperiments.html

Loads of experiments here, all null results. Can you explain how you might catch light misbehaving by the Montec experiment?

-C2 .

Hi Confused2

I liked the site on the SR experiments. Book-marked it in fact.

The light in my experiment is not "misbehaving". In fact the light just travels in a straight line at the speed of light.

I have two points in space A (the light source) and B (the CCD) a fixed distance apart (length of tube). The tube travels at a velocity Vt in space. The time it takes for the light to go from A to B will allow B to move some distance X in the Vt direction. Rotating the tube provides a orthogonally time varying frame of reference with respect to the light. The distance X will trace out a circular path on the CCD.

Isn't that what the Michelson-Morley experiment was supposed to do?
http://galileoandeinstein.physics.virginia.../michelson.html
-C2 .

Hi Guest_Confused2 (Confused2 ?)

The Michelson-Morley experiment was an attempt to measure the change in the speed of light due to the Earths movement through an aether that supports transverse light wave propagation. It was not used to measure "aberration of light" due to the velocity of the Earth.

Um.. doesn't this give us (ultimately) Earth acceleration relative to an inertial frame. Enough Montec measurements would (hopefully) show we go (approximately) round the Sun .. is this a better way of doing that or something else? Given v^2 = u^2 + 2as .. without knowing u^2 .. ?

-C2 .

Edit..

"displaced from its true position by an amount which depends upon the velocity of the observer " .. if the velocity does not change then the displacement does not change and there would be nothing to measure.

Note credibility factor ..

Hi Confused2

The aberration of light measured by astronomers is 20.5 arc-seconds. This is from the change in the absolute velocity of the Earth due to its orbit around the sun (the second method described in my first post on this subject).
This calculates out to be approximately 29.788 Km/s.
Earth's orbital velocity around the sun is 29.72 Km/s from other sources. These two results are close. This means that "aberration of light" works and is a valid way to measure velocity.
The values for the velocity of Earth through the cosmos ranges from 220 Km/s to 370 Km/s from astronomical observations.

My experimental apparatus is a method, which is open for discussion, that will (hopefully) be able to measure the total aberration of light due to Earth's motion.

One should be able to measure any vector component of the total aberration of light with the proper orientation of the device.

I've actually read a bit more of your original post .. (now!). Your laser is in the same frame as your ccd. No motion. Same as Michelson-Morley. Nothing to detect. I suggest space doesn't move .. there's nothing there to move.. this is why relativity works. Please suggest what you hope to find in space?
-C2

Hi Confused2

There is motion in the rotation of tube which is known and motion of the tube through space which is not known. Michelson-Morley did not try to measure displacement of the light beam at right angles to the light path on a continuous basis.

If emitted light is independent of its source then the source may move at right angles to the light and not influence the emitted light. Similarly the light will not change direction to hit the target if the target moves at right angles to the light. In order to hit a moving target you must aim at its future position. Similarly aiming at a moving targets present position will miss. The amount you miss by is dependent on the speed of your bullet (photon), the speed of your target (CCD) and the distance to the target (length of tube).

I guess you could say that I am using the emitted light as an absolute reference since I know its speed and direction which do not change.

If emitted light is not independent of its source then my experimental device will fail.