Relativistic Muons and Time Dilation

Link to the demonstrator: in English


Age: 16-18

Duration: 3 hours

Equipment: PC with internet connection

Contact details

Author: Emmanuel Chaniotakis (EA) with the support of Christina Parotidou
Contact: info[at]frontiers-project[dot]eu


This demonstrator introduces students to the phenomenon of relativistic time dilation, one of the most striking consequences of Einstein’s Special Theory of Relativity. Utilizing a virtual simulation, students will investigate the rate of decay in flight of muons produced in elementary particle collisions in the atmosphere and will be guided to explain their findings using Einstein’s theory of Special Relativity and the phenomenon of time dilation. This scenario is a follow-up from the educational scenario on cosmic muon decay.


Learning outcomes:

  • To introduce students to the concept of radioactive decay.
  • To introduce students to cosmic ray muons. 
  • To introduce students to relativistic time dilation.
  • To initiate a discussion about cosmic rays. 


Prior knowledge:

  • Exponential decay
  • properties of muons, 
  • exponential functions
  • The “eV” unit of energy and its multiples. 


Concepts introduced:


  • Muon Decay in flight
  • Relativistic Time 
  • Dilation


Learning intentions:

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

  • discuss the properties of muons.
  • discuss the phenomenon of radioactive decay.
  • explain the phenomenon of relativistic time dilation in simple terms. 
  • Plot data in excel and fit them with an exponential function.
  • Explain the concept of flux and be able to calculate it for given parameters.


Key activities:

  1. Performing simple kinematics calculations 
  2. Performing a simple counting experiment for different altitudes.
  3. Collecting data, plotting them and fitting them
  4. Develop hypothesis and test using calculations
  5. Summary presentation

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