A shining light casts a horizontal beam through a spacecraft. Which two observers would see this beam of light in the exact same way?
Answer
A
an observer on Earth while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is moving at a constant velocity
B
an observer inside the spacecraft while the spacecraft is accelerating and an observer inside the spacecraft while the spacecraft is at rest
C
an observer on Earth while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is at rest
D
an observer inside the spacecraft while the spacecraft is at rest and an observer inside the spacecraft while the spacecraft is moving at a constant velocity