Next Bug Future wrote:

A radio frequency (RF) resonant cavity thruster, EmDrive, is a controversial proposed type of propellentless electromagnetic thruster with a microwave cavity, designed to produce thrust from an electromagnetic field inside the cavity.
Researchers José Croca and Paulo Castro from the Centre for Philosophy of Sciences of the University of Lisbon in Portugal suggest that not only could pilot wave theory explain the mysterious behavior of the EM drive, it could help to make it even more powerful.
Applying a pilot wave theory to NASA’s EM drive frustum [or cone] could explain its thrust without involving any external action applied to the system, as Newton’s third law would require.
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If a pilot wave does explain the thrust behind the device, then it could also lead to a way to make the propulsion system even more powerful in future, and it’s as simple as tweaking the shape.
“We have seen that the effect could be enhanced using a different shape for the frustum,” said Castro. “In fact a trumpet exponential form is expected to increase the thrust.”
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