Collège Villeneuve, Grenoble, France World Year of Physics, May 23rd-28th 2005 Patrice Ballet and François Graner

This diamond-shaped soap film goes down from the ceiling to the floor. Colors are entirely natural! The picture is taken from the bottom. It is difficult to figure out the size (it is easier on the other picture): it is 10 meters high and 3 meters wide! Click on the image if you want to enlarge it (picture by F. Mondot); click here to see how it is formed (movie by E. Bourreau, 500 k).

Blowing on it creates a large bubble. The persons give you an idea of the scale of the pictures. Click on the image if you want to enlarge it (picture by F. Mondot); click here to see how it is formed (movie by E. Bourreau, 500 k).

How do we make it?

We simply use two vertical nylon wires, attached between the ceiling and the floor:

• There is a bottle of water (with dishwashing liquid) at the top.
• The water drips on the wires.
• When we pull the wires apart (click here to see the movie), a soap film forms between them.
• The soap film lasts several seconds or minutes, according to its width.
• We can blow on it and form a giant bubble (click here to see the movie).
• We can make the film automatically with motors, or let the spectators make it manually.

For more details, see the website of Maarten Rutgers who gave us a lot of useful advices. Thanks, Maarten!

Why do we make it?

This is not part of our scientific research.
It's an attractive part of teaching projects, some of which involve whole classes, while some involve small groups.

• At secondary school level, it helps introducing:
  
  • physics: stability and applications of soap films, bubbles and froths
  • chemistry: fabrication of soap
  • life sciences: hygiene and applications of soap
  • mathematics: geometry of surfaces
  • technology: automatisation methods
  • plastic arts: structures under tension
  
  
• At an advanced level, the soap film is linked with various notions:
  • presentation and discussion of surface tension and its effects
  • visualisation of the flow within the film, introduction to two-dimensional fluid mechanics
  • discussion of the nature and origin of the colors
  • mathematics of minimal surfaces

Support

We belong to the Laboratoire de Spectrométrie Physique. For the World Year of Physics, we are helped by Jean-Louis Hodeau and our administrations: the CNRS, the Université Joseph Fourier - Grenoble I, the Ministry of Research.

Patrice Ballet and François Graner are looking at a "small" 5 meters high film (picture by F. Boseggia).