low graphics version | feedback | help
You are in: Sci/Tech
 Front Page World UK UK Politics Business Sci/Tech Health Education Entertainment Talking Point In Depth AudioVideo
Tuesday, 21 March, 2000, 12:24 GMT
Double bubble is no trouble

 Nature will allow bubbles like this...
By BBC News Online science editor Dr David Whitehouse

Four mathematicians have announced a proof of the so-called Double Bubble Conjecture - that the familiar double soap bubble is the optimal shape for enclosing and separating two chambers of air.

In an address to the Undergraduate Mathematics Conference at the Rose-Hulman Institute of Technology in Indiana, Frank Morgan of Williams College, Massachusetts, announced that he, Michael Hutchings of Stanford, and Manuel Ritori and Antonio Ros of Granada, had finally proved what the double soap bubble had known all along.

When two round soap bubbles come together, they form a double bubble. Unless the two bubbles are the same size, the surface between them bows a bit into the larger bubble. The separating surface meets each of the two bubbles at 120 degrees.

Mathematicians have expressed surprise that when two bubbles are joined in this way that the interior surface that separates them is not bowed all that much.

Minimal energy

Explaining why this is so has been a puzzle for a long time. Scientists speculate that the bubble surface conforms to a "minimal energy" state that is stable - but proving it is another thing.

 ...but not like this
This shape is now known to have less area than any other way to enclose and separate the same two volumes of air. Other shapes have now been shown to be unstable by a new argument that involves rotating different portions of the bubble around a carefully chosen axis at different rates.

The breakthrough came while Morgan was visiting Ritori and Ros at the University of Granada last spring.

In 1995, the explanation of the special case of two equal bubbles was heralded as a major breakthrough when it was proved with the help of a computer. The new general case involves more possibilities than computers can now handle.

The new proof uses only ideas, pencil, and paper. What is more, a group of students has extended the theorem to 4-dimensional bubbles and in some cases five.

Graphics by John Sullivan

 Search BBC News Online Advanced search options
 BBC RADIO NEWS BBC ONE TV NEWS WORLD NEWS SUMMARY BBC NEWS 24 BULLETIN PROGRAMMES GUIDE
See also:

19 Nov 99 | Sci/Tech
Mathematicians crack big puzzle
08 Mar 00 | Sci/Tech
Unpacking a particle problem
Internet links:

The BBC is not responsible for the content of external internet sites

 Links to more Sci/Tech stories In This Section Astronomy's next big thing Ancient rock points to life's origin Mobile spam on the rise Giant telescope project gets boost New hope for Aids vaccine Replace your mouse with your eye Device could detect overdose drugs Wireless internet arrives in China Chicago steals a lead on Silicon Valley Net body accused of bullying tactics Phones, tones and mobile music Skies open for UK astronomy Q&A: Astronomy super-club Artificial star enhances telescope's vision Perfect for washing and astronomy Russia plans to put people on Mars 'Windiest' farm goes live National park 'goes live' Fish policies 'ignore evolution' Europe tightens GM labelling rules Death knell for island hedgehogs Big eye on the sky Complex molecule surprises astronomers Fossil was 'first walker'

 ^^ Back to top News Front Page | World | UK | UK Politics | Business | Sci/Tech | Health | Education | Entertainment | Talking Point | In Depth | AudioVideo  ---------------------------------------------------------------------------------- To BBC Sport>> | To BBC Weather>> ----------------------------------------------------------------------------------© MMIII | News Sources | Privacy