chuck wrote:It just feels odd that something that massive moves around at all.
The earth sinks where you are standing or sitting from your weight Chuck.
I once measured a 2-meter standard bar for the National Radio Astronomy Observatory. The thing was too long to include the laser interferometer on the surface plate so I mounted it on a tripod. The group that brought the 2-meter bar to me gathered around the surface plate to watch the set-up. As I zeroed the interferometer they all gathered around the tripod. As I moved the retroreflector to the other end of the bar they followed. The 2-meter bar was way off from 2 meters. I moved the retroreflector back to the zero end of the bar and the zero had drifted 292 micrometers. I let them know the zero had drifted and they all came down to the other end to see. As they returned the zero returned to about zero. That was the second time I had noticed the ground sinks where people are standing. I asked them all to freeze for the next measurement and the bar measured within the specified requirement.
The earth is pretty massive but it is like jello, not very firm.



