Can the effects of a person's mass upon the local gravitational field be detected and measured remotely? As the title suggests, Can the effects of a person's mass upon the local gravitational field be detected and measured remotely?
I am aware any mass produces and effects gravity but couldn't find anything in my searching if it is possible or theoretically possible to detect this effect remotely.
 A: The gravitational field of small objects can be measured. In fact as far back as 1797 Henry Cavendish measured the gravitational field from lead spheres. He used pairs of spheres of mass 158kg and 0.73kg, so for a person weighing say 70kg the same method is in principle possible, although in practice people are an inconvenient shape for doing the experiment and you'd probably have to kill them to get them still enough.
However you'd need to get pretty close for the field to be measurable. In the Cavendish experiment the distances used were around 0.2m. Once you get more than a few metres away I doubt any existing instrument would be sensitive enough to measure the gravitational field from a person.
A: According to this site
http://en.wikipedia.org/wiki/Gravimetry
Gravimeters can have a accuracy of up to 0.002 mGal (= 2*10^-8 m/s^2)
The gravity of a person of lets say 100kg at a distance of one meter is approximately
G * m/r^2 = 6.7*10^-9 m/s^2
So that person would need to weigh at least 300kg to be detectable.
