I ran across this thought provoking paper, which I now call to your attention:
“Guidelines to Antigravity”, Robert L. Forward
American Journal of Physics 31, 166 (1963); doi: 10.1119/1.1969340
View online: http://dx.doi.org/10.1119/1.1969340
Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
treborsci@verizon.net
www.sciamanda.com