Space, Time, and Matter

[sjastro]

Ok... were jumping around definitions here... the 3rd observer would provide the axis, to intersect the source and receiver line of light, thus allowing rotation, thus allowing you to apply your tangental calculations.

Your definition of the experiment, has added a 3rd "chopper cam" top down observer, external to the experiment....


How does the closed frame, with all components on the turntable... know it's turning?
How does the closed frame know where it's center is?

The only way to get a source and receiver to rotate, so that you may apply your tangental mathematics, is the addition of a 3rd observer, providing the axis.

Incomprehensible.

The correct way is to measure the centrifugal force at two points in the rotating frame. Since the centrifugal force is directed radially outwards, the intersection of the two radial lines will mark the centre.

Once the centre is known the radii at the points can be measured.

The tangential velocity is calculated by the formula
Tangential velocity = ((Centrifugal force X radius)/mass)^0.5

Regards

Steven

[Outbackmanyep]

I didn't think there was such as thing as centrifugal force, i thought it was always centripetal.

[Jarvamundo (Alex)]

What you have failed to take into consideration is that your universal frame of reference is in fact rotating relative to the observer.

The photographic plate (or ccd) is on the turntable. As you said before Steven:

Originally Posted by sjastro

Put the CCD on the turnatable and you won't get an interference pattern.
The CCD is now the "observer".
This is the same as rotating the room containing the observer and the interferometer. The observer is now stationary relative to the interferometer as they are now both in the same frame of reference.

Sagnac did just this.

He was right, universal frame = the medium which light travels through = aether.

Anyways... as Mark said we are going over it again.

The differences in our views have been made several times. You wanted the ccd on the table... it's on there... and you're still not happy.

I don't know where to go from here.

outta here.

All the best,
Alex

Great reference here for those interested on history of the Sagnac experiment, and the modern interpretations.

http://works.bepress.com/cgi/viewcon...milan_meszaros

[Jarvamundo (Alex)]

Originally Posted by sjastro

Incomprehensible.

The correct way is to measure the centrifugal force at two points in the rotating frame. Since the centrifugal force is directed radially outwards, the intersection of the two radial lines will mark the centre.

Once the centre is known the radii at the points can be measured.

The tangential velocity is calculated by the formula
Tangential velocity = ((Centrifugal force X radius)/mass)^0.5

Regards

Steven

But one ponders... how is this center "known"?

The center is defined by the axis of rotation provided by a 3rd point, dot, observer.

Draw a line on a piece of paper. If you want this line to rotate, it will need a 3rd point, providing an axis.

Otherwise as you correctly mention, without this 3rd observer

Originally Posted by sjastro

This is the same as rotating the room containing the observer and the interferometer. The observer is now stationary relative to the interferometer as they are now both in the same frame of reference.

= Sagnac experiment.

[sjastro]

Originally Posted by Outbackmanyep

I didn't think there was such as thing as centrifugal force, i thought it was always centripetal.

The centrifugal force is a "fictitious force" equal in magnitude but opposite in direction to the centripetal force. (Newtons third law at work).

The effects of a fictitious force are measurable.

Regards

Steven

[sjastro]

What you have failed to take into consideration is that your universal frame of reference is in fact rotating relative to the observer.

Originally Posted by Jarvamundo

The photographic plate (or ccd) is on the turntable. As you said before Steven:

You fail to grasp that the above quotes are not equivalent.
The first quote refers to what an observer sees from their frame of reference.
The second quote is the rotating frame itself.

For example the Earth rotates in an easterly direction, but an observer on Earth sees the sky (your so called universal frame) is rotating in a westerly direction.

Steven

[sjastro]

Originally Posted by Jarvamundo

But one ponders... how is this center "known"?

The center is defined by the axis of rotation provided by a 3rd point, dot, observer.
Draw a line on a piece of paper. If you want this line to rotate, it will need a 3rd point, providing an axis.
Otherwise as you correctly mention, without this 3rd observer

So you keep on repeating. It is still incorrect despite how many times you care to mention it.

The centre is defined where the centrifugal and centripedal forces are equal to zero. That is all that is required.

Steven