The Failed Experiment: Michelson Morley Experiment Quiz

If scientists in the 19th century believed light required a medium called ether to travel, and if the Earth is moving through space, then there should be a measurable "ether wind" affecting the speed of light.

If the experiment resulted in a "null" finding, then it showed the speed of light remained constant in all directions; therefore, it disproved the idea that motion through the ether changed the speed of light.

If sound requires air and water waves require water, then early physicists assumed light required a physical substance to oscillate; if they named this substance after the Greek word for "upper air," then it is the luminiferous ether.

If the experiment required splitting a light beam into two perpendicular paths and recombining them to look for interference patterns, then the specific device created for this task is the Michelson Interferometer.

If the experiment proved light speed does not change with the observer's motion, then this became a core postulate for Einstein; if no medium was detected, the ether was rejected, leading to the development of the spacetime concept.

If the "ether wind" was expected to change based on the direction of Earth's travel, then the researchers needed to rotate their equipment to compare light speeds in different directions relative to Earth's orbit.

If the goal was to find the ether and the researchers failed to detect it, then the experiment was a failure of its original premise; however, if this failure revolutionized physics by leading to relativity, then it was highly successful.

If the math predicted a shift of 0.4 fringes and the actual observation showed a shift of less than 0.01, then the expected signal was effectively zero; if a signal is zero or non-existent, it is a null result.

If a person throws a ball from a moving train, the speeds add up (v1 + v2); if light were like the ball, it would be faster when moving with the Earth's orbit; since the experiment showed light speed stays the same, it contradicted Newtonian rules.

If a single source of light is split into two paths and then brought back together, then the wave peaks will either line up (constructive) or cancel (destructive), creating the "fringe" pattern used to measure speed changes.

If light behaves like a swimmer in a river, then traveling upstream and downstream (parallel to the current) takes more time for a round trip than crossing the river and back; thus, the ether wind should have caused a delay in one path.

If the speed of light is a universal constant measured at 299,792,458 m/s, then in scientific notation, this value is expressed as 3 * 10^8 m/s.

If the experiment was extremely sensitive to vibrations and needed to be rotated 360 degrees to test all directions, then floating a heavy stone slab on liquid mercury provided the most stable and frictionless method possible.

If the interference fringes depend on the difference in path length, then even a microscopic change in the arm length due to heat or vibration would create a false signal; therefore, stability was the greatest engineering challenge.

If the experiment proved that the speed of light is constant regardless of the observer's motion, and if Einstein used this fact as his second postulate in 1905, then the resulting theory is Special Relativity.

If historical records confirm that Albert Michelson and Edward Morley collaborated in Cleveland, Ohio, during the late 1880s, then the 1887 date and location are factually correct.

If two light waves overlap, their amplitudes add or subtract based on their phase; if this results in a visible pattern of stripes on a detector, then those stripes are the result of interference.

If a laser provides a "coherent" and monochromatic light source that stays in phase over long distances, then it is much more precise for measuring tiny shifts than the white light or lamps used in the 19th century.

If an interferometer can measure distances to a fraction of a wavelength, then it is used for gravity waves (LIGO), high-tech manufacturing (metrology), and medical imaging; however, microwaves use radiation to heat water, not interference to measure length.

If every attempt to measure a change in light speed due to Earth's motion failed, and if this led to the successful predictions of relativity, then we must conclude that light speed does not change for any inertial observer.