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Bubble: The film around the bubble was up to eight degrees colder
Photo: Ilhana Babic/EyeEm/Getty Images
They bubble in the beer, pile up as foam on waves and cavort between your teeth: bubbles have been scientifically well studied.
A French research team has now surprisingly made a new finding: the shell of soap bubbles is significantly colder than the surrounding air temperature.
The discovery was pure coincidence, reports the three-person team from the University of Paris-Saclay in Paris.
Actually, François Boulogne, Frédéric Restagno and Emmanuelle Rio investigated how stable soap bubbles are.
They also happened to take temperature measurements for their experiments.
They found out that the film around the soap bubbles is colder than the surrounding air, the physicists report in the journal Physical Review Letters.
And with all soap bubbles.
The soap bubbles consisted of conventional washing-up liquid, water and glycerin.
After the scientists made their discovery, they tried to manipulate the temperature of the bubble envelope.
They changed the temperature in the room, experimented with the humidity and varied the composition of the soap bubbles.
In this way, they were able to create bubbles whose outer film was up to eight degrees colder than the surrounding air.
Useless knowledge?
The research team cannot yet explain exactly why the soap bubbles are so cool on the outside.
Presumably, however, evaporation is responsible for the effect when the bubbles form.
The longer the soap bubbles floated through the room, the warmer their outer shell became.
After a while, the soap bubbles were just as warm as the surrounding air.
What is the experiment good for?
The researchers suspect that the temperature differences in the bubbles could affect their stability.
Now they want to find out exactly why the soap bubbles are cooler and whether this can possibly be used.
Because the stability of bubbles plays an important role in many industrial sectors - and also for children who play with soap bubbles.
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