Another day, another groundbreaking physics experiment about bubbles. Although scientists have long understood the behavior of a single soap bubble, they have not been able to mathematically describe the behavior of clusters of bubbles, otherwise known as foams. As you can see in the photo above, when one bubble pops in a group like this, the other bubbles quickly rearrange themselves to balance out the cluster—but because the forces behind all that shapeshifting are different from the forces determining when each bubble pops, it's difficult to make a computer model that can incorporate all phases of a foam's life. Now, scientists have solved the problem by taking a hint from climate models, which have long struggled to figure out how local events (a volcanic eruption in Hawaii or a single bubble in a foam popping) influence more widespread changes (global temperature changes or the foam entirely collapsing). The new model splits up a foam's life into three phases, the researchers report online today in Science: rearrangement, in which the group of bubbles slip and slide around each other to achieve stability; drainage, in which gravity draws the fluid inside a bubble's membrane toward the earth; and rupture, in which a bubble's membrane becomes so uneven that it finally pops, forcing the remaining bubbles to rearrange themselves and allowing the cycle to begin again. While the researchers tested their model using—you guessed it—soap bubbles, they hope their work will help materials scientists better understand and control the properties of solidified foams made of metal and plastic, which are vital for applications that require materials that are both light and strong—like prosthetic limbs.
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