Michelson-Morley experiment

2. • To attempt to measure the motion of the
Earth through the “Aether”, the non-
viscous, invisible, and incompressible
medium through which light waves were
thought to propagate
 If the apparatus is moving through the Aether,
parallel to one of the beams, there would be a
delay between the arrivals of the two beams

3. • Albert Michelson’s design was not sensitive enough
• Vibrations of footsteps from the surrounding area was
skewing the results
https://perg.phys.ksu.edu/vqm/laser
web/ch-10/10-1.gif

4.  Teamed up with Edward Morley to create a
better design
 Situated the interferometer on a large stone
slab which floated on a pool of mercury

5.  This significantly increased the reliability of the
results
http://upload.wikimedia.org/wikipedia/com
mons/8/8a/On_the_Relative_Motion_of_the_
Earth_and_the_Luminiferous_Ether_-
_Fig_3.png

6.  No delay between the beams regardless of
which direction the interferometer was
positioned
 Demonstrated that the speed of light is the
same for all observers
 Disproved the existence of the Aether

7.  Large-scale interferometers are used today in
an attempt to prove the existence of
gravitational waves, predicted by Albert
Einstein
 These interferometers have arms spanning
roughly 4km each, allowing them to detect
length changes of up to one hundred-millionth
of the diameter of a hydrogen atom