# Observation of gravitational wave strain.

1. May 23, 2012

### wipeoutscott

Hello, I have a question or two about gravitational waves.

My current job is basically to measure atomic strains using x-ray diffraction. I have managed to reduce the error in measurement low enough to reveal an annual sine wave in my data for a sample which should not contain any strain. I first ruled out temperature as a cause, then noticed the oscillation is in good agreement with Earths distance from the sun. Further analysis has shown that the more minor oscillations trend very well with the azimuth and elevation of the moon at the time for a short enough period that the sun distance has not moved much.

The combination of gravitational effects from the sun and moon appear to be influencing the measured strain on the atomic scale. Searching on Google regarding gravity and strain has kept pointing me to gravitational waves.

The annual oscillation is on the order of 10^-5, from what I have found online gravitational waves should be many orders of magnitude weaker than this. However this seems too high to be a direct result of gravity, or am I wrong?

I would also like to use the sun/moon position at the time of measurement to predict my result. However I'm not sure how to superimpose the two effects, especially considering gravitational waves!

2. May 23, 2012

### Vorde

I don't know details about your actual experiment or what you are measuring (my lack of knowledge), but I would be much more surprised to find out that you were measuring gravitation waves instead of the simple change in gravitation effect from the distance between the earth and the moon/sun changing. Its pretty easy to determine the gravitational force (mathematically), and there are pretty exact values in terms of the difference in distance between the sun/moon at apogee and perigee, so I would crunch the numbers to predict the difference in force, and see if that lines up with experiment.

3. May 30, 2012

### wipeoutscott

Thanks for your response Vorde. I've ran some simulations in Pro/e Mechanica and found the gravitational effects to be orders of magnitude smaller than the strains I am observing.
I'm starting to realize the strains I am observing are not due to the atomic spacing but very slight changes in the incident beam wavelengths (the other variable in Bragg's law). I've ran some basic numbers regarding gravitational red-shift that should occur from the sun's gravity and this is starting to make more sense.