[stack]

@stack

It isn't worth my time.  Every source tells the same history as far as I am aware.

If you have any support for your view, I am intereted in it - however you are not obligated to share (it's just the right/best thing to do - for you and all of humanity)

From Michelson & Morley's original experiment paper, "On the Relative Motion of the Earth and the Luminiferous Ether":

"Let V= velocity of light.

v= velocity of the earth in its orbit,
D=distance ab or ac, fig. 1.
T=time light occupies to pass from a to c.
T =time light occupies to return from c to a/, (fig. 2.)



In the first experiment one of the principal difficulties encountered was that of revolving the apparatus without producing distortion; and another was its extreme sensitiveness to vibration. This was so great that it was impossible to see the interference fringes except at brief intervals when working in the city, even at two o'clock in the morning. Finally, as before remarked, the quantity to be observed, namely, a displacement of something less than a twentieth of the distance between the interference fringes may have been too small to be detected when masked by experimental errors."

Note the quantity to be observed by the apparatus. A byproduct of the distance measurement is motion or the lack thereof.

And note that Michelson & Morley refer to their effort throughout the original paper as an "experiment". What you consider it to be is neither here nor there.

[jack44556677]

Cool, so we're all on the same page then.

The "mmx" (holy hell...) was for the measurement of velocity by using an interferometer, specifically designed, to measure it (not distance).

I'm glad we cleared that up!

[stack]

Cool, so we're all on the same page then.

The "mmx" (holy hell...) was for the measurement of velocity by using an interferometer, specifically designed, to measure it (not distance).

I'm glad we cleared that up!

The experiment was about motion The Interferometer itself was the tool devised to measure hyper-precise distance and as a byproduct motion or no motion.

Interferometers are widely used in science and industry for the measurement of small displacements, refractive index changes and surface irregularities. In most interferometers, light from a single source is split into two beams that travel in different optical paths, which are then combined again to produce interference; however, under some circumstances, two incoherent sources can also be made to interfere.[3] The resulting interference fringes give information about the difference in optical path lengths. In analytical science, interferometers are used to measure lengths and the shape of optical components with nanometer precision; they are the highest precision length measuring instruments in existence.
https://en.wikipedia.org/wiki/Interferometry

Yep, all cleared up: MMX was an experiment and Interferometers measure distance. Cool.

[jack44556677]

The experiment was about motion The Interferometer itself was the tool devised to measure hyper-precise distance and as a byproduct motion or no motion.

No, no one thinks that except you. The interferometer was invented for the experiment, and it was designed to measure velocity. Obviously the measurement comes in the form of an infintessimal distance, don't be a pedant just for prides sake.

Even the page you linked to to support your baseless claim, says nothing about it.  I know you are trying so very hard to avoid just saying - I was wrong. Pride is a disability and a liability.  It's not hard.  I say it ALL THE TIME. I make mistakes too!

Or you could provide any support for your claim... I think you just assumed it - didn't you...

As I said, it does SOUND plausible, however with just your assumption to support your claim...

[stack]

The experiment was about motion The Interferometer itself was the tool devised to measure hyper-precise distance and as a byproduct motion or no motion.

No, no one thinks that except you. The interferometer was invented for the experiment, and it was designed to measure velocity. Obviously the measurement comes in the form of an infintessimal distance, don't be a pedant just for prides sake.

Even the page you linked to to support your baseless claim, says nothing about it.  I know you are trying so very hard to avoid just saying - I was wrong. Pride is a disability and a liability.  It's not hard.  I say it ALL THE TIME. I make mistakes too!

Or you could provide any support for your claim... I think you just assumed it - didn't you...

As I said, it does SOUND plausible, however with just your assumption to support your claim...

"In analytical science, interferometers are used to measure lengths and the shape of optical components with nanometer precision; they are the highest precision length measuring instruments in existence."

[jack44556677]

That's all well and good.

Where is the support for your claim that the interferometer was FIRST created to measure distance and then repurposed to be used to measure motion instead?

[Iceman]

If you measure the distance to something once, then you measure the distance to that same thing again after some amount of time, if theres a difference between those two measurements... you've measured motion.

Not rocket appliances

[JSS]

That's all well and good.

Where is the support for your claim that the interferometer was FIRST created to measure distance and then repurposed to be used to measure motion instead?

What is the purpose of focusing on what interferometers were FIRST built to measure?  Does it make any difference at all to what they CAN measure?  You have admitted that they can measure distance, so what exactly would it prove one way or the other?  It's like asking what the tape measure was invented for, to measure distance or to be easily portable?  Doesn't matter, they still do both.

As I said, I've built an interferometer and used it before and can verify it can measure distances very precisely.  I've used them to measure the shape of primary telescope mirrors and verify the curve and smoothness of ther optical coatings.  And of course I experimented with it once I had it all set up.  I can verify, personally that they do indeed measure distance, and they do work very well.  There is no reason the LIGO interferometers would not work just as well as my home-brewed version.

LIGO uses interferometers to measure distance because they are extremely good at doing that.  When gravitational waves pass through the two arms, the interferometers detect the change in distance and record the results.  This is direct evidence of gravitational waves, they are literally measuring space stretching and compressing in real time.

[jack44556677]

@JSS

What is the purpose of focusing on what interferometers were FIRST built to measure?

You might have arrived late to the party.  Stack has made an assumption that they are attempting to disingenuously/erroneously pass off as historical fact without any support (even anecdotal / personal "reasoning").  I am endeavoring to help keep them honest with themselves and others (only if they wish it, however). 

What the interferometer does, and how it works, is actually much more relevant to the shape of the world and the observation of various phenomena (several erroneously attributed to the earth's presumed rotation) than it appears at first glance!

I agree that it is a minor point, but if it weren't important to understand I would have dropped it long before now.  The other reason I continue to focus on it is because I have made mistakes like this before, and I wish to help stack to do better - if I can and they will allow me.

Doesn't matter, they still do both.

In the case of the interferometer, that is completely correct.  However what is key is HOW it is doing it.  We might need another thread where all this jibber jabber can go and stop cluttering this one.

There is no reason the LIGO interferometers would not work just as well as my home-brewed version.

Definitely true!  In fact, there is every reason to suspect that they would work much better!  However, ligo's arms are of fixed length, calibrated, and insulated from local noise and vibration.  Great pains are taken to avoid any path length deviation.  It is true that a vibration could cause a mirror (or the arm itself) to move and cause fringe patterns - it's just that that is not what causes the fringe patterns in ligo - nor is that the source of the fringe patterns in stationary and uniformly moving FOG's/RLG's.

When gravitational waves pass through the two arms, the interferometers detect the change in distance and record the results.

That is their earnest belief/conviction, yes.  However, it is not what is happening.  The interferometer is measuring perturbation in the medium of which light is comprised and travels within.  There is no "gravitational wave" - that is largely a made up term to mislead laypeople into thinking "gravity" has been found/detected.

This is direct evidence of gravitational waves,

It is direct measurement of the light waves traveling in each arm.  From it we can infer about the media through which light travels and is comprised.  The arms of the interferometer did not change length.  Noise and vibration did not move the mirrors.  The path lengths remain fixed as best as can be achieved by ungodly amounts of money being thrown at the problem.

they are literally measuring space stretching and compressing in real time.

This is essentially correct in my view, assuming the data is real - which is highly suspect.