If you want to investigate Gravity waves, start with the tides of our oceans.
Carefully note the precise lag between the tide rising compared to the overhead orbital position of our Moon. That lag helps indicate the propagation speed of Gravity.
If you want to investigate Gravity waves, start with the tides of our oceans.
Carefully note the precise lag between the tide rising compared to the overhead orbital position of our Moon. That lag helps indicate the propagation speed of Gravity.
So you think that two points with the same longitude always have high tide at the same time?
You have to account for momentum, and that is hard in the ocean. It takes time for the accelleration of the water to catch up, and the signl to noise ratio is very, very low.
The lowest mass objects are easier. Light has mass, but in a laser in a vacuum, it is pretty precise.
Then again, the first time I heard of gravity waves, I thought it was obvious, actually. It is so weak, though, that is amazingly hard to measure directly.
Any lag is swamped by the lagging response of ocean. Besides, tides are caused by a inbalance in centrifugal force and gravity, the earth moves through the already arrived gravitional field of the moon.
A more sensitive test of gravitional/inertial interaction is available in measuring physical libration on the moon. The moon's rotation is tidally locked to its sidereal orbital period, 27.3 days. However, because of the eccentricity of the moon's orbit, its orbital motion varies as it comes closer and further from the Earth, but its rotation is more uniform, so she presents a slight different aspect to the Earth during the month.
Copyright Antonio Cidadao.
As the aspect varies, the Earth pulls more strongly on the heterogenous lumps in the moon, effecting a torque. This results in an actual change in the rotational speed of the moon, with respect to the distant stars, called physical libration. (The effect above is overwhelmingly apparent libration, caused by the non-uniformity of the moon's orbital speed.)
There are corner reflectors on the moon whose displace should exhibit the effects of this torque far more accurately than anything we might be able to do with tides. The laws of propagation of errors are against you I fear. While it is possible to tease out the measurement of physical librations, these measurements probably cannot ever be sensitive enough to reveal lags associated with the speed of gravity.