In the full book he clearly states that anyone who has learned how to make artificial gravity will have propulsion as well and be able to completely rule the world. And of course admiral Byrd experienced that when he went down to the Antarctic to mop up the Nazis and they sank a bunch of his ships and airplanes and he had to retreat and tell everybody that there's somebody down in Antarctica that can control the world and it's all the more interesting if Antarctica was actually not at the South Pole 8 or 10,000 years ago and therefore there might be remnants of a very large event civilization under the ice. Which of course also explains the pyrese map