The gravitor and the professor
In the 1920s, a high school student named Thomas Townsend Brown noticed something peculiar while experimenting with a Coolidge X-ray tube. When he placed the tube on a sensitive scale and applied a high voltage, its weight seemed to change depending on its orientation. This observation sparked a lifelong pursuit of what he believed was a link between electricity and gravity. Brown later attended Denison University for one year, from 1924 to 1925. During this time, he associated with professor of physics and astronomy, Dr. Paul Alfred Biefeld. Brown claimed they conducted experiments together, leading him to name the observed phenomenon the "Biefeld-Brown effect."
The effect describes the thrust generated by an asymmetric capacitor when a high voltage is applied. This capacitor typically consists of a small or sharp electrode and a larger, smoother one. When energized with voltages ranging from a few kilovolts to megavolts, a force is produced that pushes the device towards the smaller electrode. Brown was so convinced of the effect's potential that he patented a device he called a "gravitator," which he envisioned propelling future vehicles, from ocean liners to "space cars," without any moving parts. However, the nature of Brown's association with Biefeld and the extent of their collaboration remains unclear. Denison University archives have no official record of joint experiments or any paper on the effect co-authored by the two.
Ion wind or new physics?
The central controversy surrounding the Biefeld-Brown effect is the origin of the observed force. The prevailing scientific explanation is that the thrust comes from electrohydrodynamics, more commonly known as "ion wind." According to this model, the intense electric field near the smaller electrode ionizes the surrounding air molecules. These newly created ions are then accelerated towards the larger electrode, colliding with neutral air molecules along the way and transferring momentum to them. This creates a net flow of air, or an "ionic wind," that pushes the capacitor.
Brown maintained that the effect was an "anti-gravity" force, a phenomenon he termed "electrogravitics." He claimed the effect persisted even in a vacuum, which would rule out ion wind as the sole explanation. In 1965, he filed a patent claiming a net force could be produced in a vacuum up to 10⁻⁶ Torr. Subsequent experiments have yielded conflicting results. Most controlled, peer-reviewed studies have failed to detect any thrust in a high vacuum, concluding that the observed force in air is almost entirely attributable to ion wind. These experiments show that the thrust diminishes as air pressure is reduced, effectively disappearing in a vacuum. Despite this, the debate continues in some circles, with amateur experimenters and theorists proposing alternative explanations, from new physics to interactions with undiscovered fields.