From the Michelson-Morley experiment to the gravitational-wave detection Discovering and building a Michelson interferometer

Link to the demonstrator: in English


Age: > 16

Duration: 3 hours

Equipment: PC with internet connection 

Contact details

Author: Dr. Matteo Barsuglia (PCCP)
Contact: info[at]frontiers-project[dot]eu


This demonstrator introduces the concept of waves, interference, and the wave nature of light. Students are introduced to the history of the Michelson interferometer and the Michelson-Morley experiment, a groundbreaking experiment that led to Einstein’s theory of special relativity. In an historical overview, they will learn how, more than a hundred years later, the same instrument was used to detect gravitational waves, thus confirming one of the main predictions of Einstein’s general relativity. Students will experiment with a real small-scale Michelson interferometer, a powerful instrument that uses light interference to measure distances with high precision. They will learn about the basic properties of light interference and the working principle of an interferometer. Real images from the sites of the LIGO and Virgo instruments will be used to explain how modern-day interferometers are used to detect gravitational waves. Students will present their work to the class and discuss their results.


Learning outcomes:


  1. Give students an historical view of two Nobel Prize winning discoveries using the interferometer and its application to gravitational-wave detection.
  2. Allow students to understand the methodology of experimental physics by building, calibrating, and operating an instrument such as a Michelson interferometer.
  3. Introduce basic concepts of electromagnetism and light interferometry.


Prior knowledge:

  • Wave properties
  • Basics of classical optics


Concepts introduced:


  • Light interference 
  • Gravitational-wave detection
  • Power of interferometry




Learning intentions:

By the end of this descriptor, students should be able to:

  • Define the principles of light interference 
  • Explain how it can be used to measure distances
  • Test and understand the response of an instrument


Key activities:

  1. Michelson interferometer manipulation
  2. Videos to engage
  3. Data analysis and explanation
  4. Final report and discussion



By the end of this demonstrator, students should be able to answer the following:


  1. Write a couple of sentences describing what you’ve learned about the properties of light.
  2. Explain the importance of the Michelson interferometer in physics and give an historical overview of its use.
  3. Name all the main parts necessary to construct the Michelson interferometer, explain its working principle.
  4. Interpret the interference patterns observed with the Michelson interferometer.
  5. Draw similarities and differences between the original Michelson interferometer and modern-day instruments, such as Virgo and LIGO.

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