"Electromagnetism is bipolar, i.e. it attracts and repels.  We can shield X-rays, gamma rays, radio waves, etc., but what about gravity?  Gravity appears to have only one polarity - - attraction!  We have balloons, planes, and rockets that overcome gravity but can we shield against gravity?   "

Electrogravitics Systems: Reports on a New Propulsion Methodology.  Edited y Thomas Valone, M. A., P.E.  Foreword by Elizabeth Rauscher, Ph.D.  P.4 (1993)