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Name:   Jessica L.
Status:   student
Age:   10
Location: N/A
Country: N/A
Date: 1999-2001


Question:
Hello,

I love playing with bubbles and I really like to know if I can produce bubbles that are rectangular or even in the shape of a square. Can you please help me?


Replies:
Jessica,

Ask a bookseller to track down the old paperback book -- "Soap Bubbles And The Forces That Mold Them." It is excellent and it will direct you on making bubbles of very exotic configurations. Good luck and have fun.

Regards,
ProfHoff 331


Hi, Jessica !!

If I understand your question correctly, you play with bubbles produced by blowing air from the mouth through a pipe that was before immersed in water with soap, is it ?

If that is the case, then I can assure you that it is impossible to obtain another form. The round form of a bubble is most stable form among others; it is the form of our planet, the form of the Moon, of Venus, Mars, of our Sun and of the stars.

The nature looks always for low levels of energy and round is the less energetic form of a bubble.

Alcir Grohmann
Beschaffung SAM


You have chosen a fascinating subject for a hobby. The fundamental principle of soap bubbles and soap films is: "They assume a surface of minimum surface consistent with the boundary that constrains them."

For a single unconstrained soap film this is a sphere if there is no air movement to disturb it. For two or more bubbles fused together, the relative size of the bubbles will be that which makes the angle of contact between the spherical bubble parts equal to 120 degrees -- it all comes out of the physics -- this is the shape that forms a minimal surface for the collection of two or more fused bubbles.

A "free" bubble will always be a sphere of part of a sphere. You can make rectangular, cubical bubbles be suspending the bubble film on a wire frame of the desired shape. In fact, this has "trick" has been used by physicists to find the geometry of minimal surfaces if they need a "hint" about how to treat the problem theoretically.

Three books you may find interesting are: "Bubble-ology" published by Lawrence Hall of Science (has soap bubble recipes and no math).

"Soap Bubbles: Their Colors and Forces that Mold them" by C. V. Boys (an older book but for many years the classical book on the topic of bubbles -- somewhat more advanced in the math).

"The Science of Soap Films and Soap Bubbles" by Cyril Isenberg ( a more mathematical treatment, but there are color pictures of soap films formed on wire frames of different geometries ).

Most soap recipes call for glycerin. If you purchase this in a drug store it is very expensive. However, you can obtain it from a local farm and animal supply store very inexpensively.

Have fun,

Vince Calder


Dear Jessica:

I recommend that you find a copy of the book "Soap Bubbles" by Charles V. Boys. It is old (1958), but still available. Chances are that you can get it from a local library. It captures the delight of these wonderful objects, and it also deals with the science behind them.

Tom Douglas



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