A "metric" named for this physicist requires negative energy density that could be achieved using exotic matter or a Casimir vacuum. For 10 points each:
[10h] Identify this physicist who names a solution to the Einstein field equations in which a moving "bubble" compresses spacetime in front of it and stretches spacetime behind it.
ANSWER: Miguel Alcubierre [or Alcubierre metric; or Alcubierre warp drive]
[10e] The Alcubierre "warp drive" would be capable of moving faster than this "cosmic speed limit," which equals about 3 times 10 to the 8th meters per second.
ANSWER: speed of light in vacuum [prompt on c]
[10m] A spaceship using the Alcubierre drive would be in this condition, which in general relativity describes objects experiencing zero net force as they travel along a geodesic in curved spacetime.
ANSWER: free fall [or free falling]
<June Yin , Science - Physics - Relativity>