latest news regarding the EM Drive, which produces a thrust seemingly from nowhere, comes from Paul March, one of the principal investigators on the EM Drive, and was published on the NASA Spaceflight forum. The post is in reply to an unpublished paper that claims the unaccounted thrust is generated by the Lorentz force between the EM Drive and the Earth’s magnetic field, something that March says his tests prove is not true.

What it actually does is produce a tiny, tiny amount of thrust via a method that’s not entirely understood

Dr. White proposed that the EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.

In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant. This model was also met with criticism in the scientific community because

Such a vehicle would be capable of carrying two to six passengers and luggage and would be able to return to Earth in the same four-hour interval using one load of hydrogen and oxygen for fuel cell-derived electrical power, assuming a 500 to 1,000 Newton/kW efficiency EM Drive system.

http://www.iflscience.com/space/nasa-allegedly-conducts-more-successfully-emdrive-tests0