In one minute

Pfenning and Ford examine the negative energy required by the Alcubierre warp metric using quantum inequalities for a free, massless scalar field. They apply a flat-spacetime bound over sampling times much shorter than the local curvature scale, rather than solving the field theory exactly in the curved geometry. For their representative sampling choice, the resulting wall-thickness limit is roughly one hundred Planck lengths multiplied by the bubble speed in light-speed units. Their hundred-metre-radius example requires a negative energy magnitude far beyond the visible universe’s mass equivalent. Increasing the speed permits thicker walls but also increases the estimated total energy requirement. They conclude that macroscopic human-transport bubbles in this model demand unattainable negative energy, including at subluminal speeds.

The unphysical nature of 'Warp Drive'