Gravitational Waves Online Workshop

The waveform of the first detected gravitational wave. Image credit: LIGO & Virgo

Curriculum links

This workshop uses skills students will learn in the course of their physics studies and applies them to gravitational waves. It is aimed at upper high school students, broadly age 14-16 (Intermediate) and 16-18 (Advanced).

The workshop allows the students to apply their knowledge and practice their skills on cutting-edge science and real-world applications. Examples are:

  • Trigonometry (used to localise sources)
  • Graph analysis (analysing simulated data)
  • Knowledge of waves (frequency-period relationship)
  • Mathematical equation manipulation (A-level only)
  • Scale conversion (metres -> light years, megaparsec etc.)
  • Hubble’s law and expansion of the Universe

Students and teachers who have completed this have reported that their understanding of gravitational waves have increased, but also that they appreciate a greater relevance of what they are learning or teaching to gravitational wave science.

Teacher CPD materials

You can see a recording of an online Teacher Workshop, run in October 2020 as part of the 2020 IOP Wales Teacher Conference here [YouTube]. The session includes the workshop above as well as a few other aspects of gravitational wave data that may be of interest to teachers. Slides accompanying the workshop are available here: [PDF ; 50MB] [PPTX ; 230MB].

This activity has been developed in partnership with the National Space Academy and funded by the Science and Technology Facilities Council. All resources are available in both PDF and Google Docs format to allow adaptation and flexibility. Teachers who deliver elements of the workshop in new or different ways are encouraged to provide examples, either by emailing schools@astro.cf.ac.uk or using our Contact Form. Teachers who would like to request an appearance by a gravitational waves scientist when delivering the lecture can also contact us, though this is offered subject to availability.

Workshop overview

This workshop gives students the opportunity to analyse and interpret gravitational wave data. The activity is in two parts, one calculating the distance to the source, and the other determining the redshift. These results are then combined to determine the Hubble constant – the rate of expansion of the Universe.

There are 8 sets of data, so that allows for the possibility of 16 “teams”, with pairs of teams using the same dataset.

The activity comes in two levels: Intermediate (aimed at students age 14-16) and Advanced (aimed at students aged 16-18).

A teacher answer table is provided to allow checking of results, though students would not be expected to get the exact results.

The required files (including this document) are available to download or share via Google Drive:

Activity Outline

  1. Direct the students to watch the introductory video:
  2. Assign the students/teams a dataset (numbered 1-8) and either Part A or Part B. They all have access to the same instructions and datasets, so make sure they complete the correct one. The “Student” folders contain a number of files, but it is recommended that you download (or link to) the files separately, rather than sharing the link to the whole folder. The files are:
  3. There are a couple of widgets for exploring how the parameter estimation (masses and distances) works. They have identical functionality:
    • Google Sheets (will need to be downloaded/copied to be used as this is view-only)
    • Microsoft Excel (will need to be downloaded/copied to be used as this is view-only)
    • Online widget (stars with a random mass/distance, and users can move sliders) 
  4. The students should work through Part A or Part B. Common mistakes or misconceptions in the Advanced level:
    • In Part A, students need to measure the frequency and amplitude of a noisy waveform. They often forget that the amplitude is zero-to-peak (not peak-to-peak)
    • In Part A, those using data with noise added may forget that the “true” data lies in the middle of the noisy curve (so they shouldn’t use the maximum or minimum value of the noise)
    • In Part B, students may overthink the geometry, particularly at Advanced level
    • The Teacher Answers are available if you would like to check students’ answers, or identify where they may have gone wrong.
  5. Direct the student to watch a further explanatory video:

Activity Levels

The two levels are broadly similar, with a couple of differences, largely around the mathematical requirements.

At Intermediate level the strain data is noise-less and is scaled so that the factor of ~10-20 is removed, and factors in subsequent calculations are adjusted. There is no noise added to the data.

At Advanced level, the strain data is not scaled. There are also additional requirements on the students. Part A students are required to calculate the mass of the black holes, as well as their distance. Part B students must deduce the trigonometric function themselves, and are not given a graph of ().

Optional Extensions

The Advanced level student pack includes some optional sections if students get ahead of themselves. For more advanced students, then you could consider setting them the task of estimating the uncertainty on their measurement of the Hubble Constant. You could assign a suitable uncertainty to the redshifts (e.g. +/-0.01), and ask them to estimate the uncertainties involved in the distance measurements.