magical bubbles and soap films
TRANSCRIPT
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Magical Bubbles & Soap Films – March 20, 2010
Frank KühnemannPhysics Department
German University in Cairo
Magical bubbles andsoap films
Magical Bubbles & Soap Films – June 8, 2011
Water Droplets – Walking over Water
Films and Bubbles
Minimal Surfaces: Physics, Mathematics and Architecture
Films and Bubbles in Space
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Magical Bubbles & Soap Films – June 8, 2011
Water drops
Magical Bubbles & Soap Films – June 8, 2011
What gives the droplet its spherical shape?
Water molecules attract each other(surface tension)� surface like a flexible membrane, trying to reach a minimum size
� A „minimum problem“: For a fixed amount (volume) of water, what will be the shape with thesmallest surface?
� Calculation and experiments:
The Sphere
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Magical Bubbles & Soap Films – June 8, 2011
„Walking on water“
Magical Bubbles & Soap Films – June 8, 2011
Adding soap to the water
likes water(hydrophil)
dislikes water(hydrophob)
Tensid molecules have two different ends
Smaller force between the detergent molecules – reduced surface tension
Soap layer at the surface
Micelle in water
molecules
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Magical Bubbles & Soap Films – June 8, 2011
Soap bubbles
A bubble
water molecule Soap particle
Repulsion between the soapparticles breaks the film
Gravity pulls down thewater molecules
Magical Bubbles & Soap Films – June 8, 2011
How to make really large films?
Martin RutgersOhio State University
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Magical Bubbles & Soap Films – June 8, 2011
How to make really large bubbles?
http://www.worldrecordsacademy.org/games/img/free-floating-bubble-90306.jpg
Magical Bubbles & Soap Films – June 8, 2011
Colourful soap bubbles
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Waves on the water
Magical Bubbles & Soap Films – June 8, 2011
Wavelength = distancebetween two crests of the wave
Light waves
Magical Bubbles & Soap Films – June 8, 2011
λ = 0.0004 mm λ = 0.0007 mm
Different colors of light have different wavelengths λ. They are smaller than 1/1000 of a mm (0.001 mm)!(One sheet of printer paper: about 0.1 mm)
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Light waves and soap films
Magical Bubbles & Soap Films – June 8, 2011
Light hits the film � partial reflection at the front and the back
Light waves and soap films
Magical Bubbles & Soap Films – June 8, 2011
For very thin films, the two reflected waves interact= „Interference“ between the reflected waves.
� The thickness of the film controls which colorscan be seen in the reflected light.
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Light waves and soap films
Magical Bubbles & Soap Films – June 8, 2011
The wall of the soap bubble is only some 1/1000 mm thick!
Magical Bubbles & Soap Films – June 8, 2011
What to learn from soap bubbles? Geometry
Surface for one enclosed volume? � Sphere
Surface for two enclosed volumes? � Two spheres in contact
Contact area is not plane: bent towards the larger sphere
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Magical Bubbles & Soap Films – June 8, 2011
How to build the perfect honeycomb?
How to enclose the largest volume with the minimum wall material, one cell next to the other?
honeycomb Soap bubbles enclosed betweentwo plates
Magical Bubbles & Soap Films – June 8, 2011
What is the smallest area for a given frame?
Moebius Clover leaf
Which form yields a minimal surface for a given frame?Plateau problem(J.A.F. Plateau)
Calculation iscomplex� make a soapfilm model!
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Magical Bubbles & Soap Films – June 8, 2011
Architecture: Light-weight, stable structures
Sebastian Demuth
For the minimum surface all forces are balanced � only a light-weight frame is requiredSoap films replace(d) computers!
Magical Bubbles & Soap Films – June 8, 2011
Frei Otto: Minimal surface principles
Soap films
Wire models
Multihalle Mannheim
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Magical Bubbles & Soap Films – June 8, 2011
Munich Olympic Stadium
Magical Bubbles & Soap Films – June 8, 2011
Sharm El Sheikh Airport, new terminal
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Magical Bubbles & Soap Films – June 8, 2011
Prophet‘s Mosque, Medina, Saudi Arabia
Magical Bubbles & Soap Films – June 8, 2011
Saturday Morning Science - Water in space
What happens when gravity becomes negligible?
Astronaut Don Pettit, Ph.D., „Saturday Morning Science“Experiments aboard the International Space Station, February 2003
http://spaceflightsystems.grc.nasa.gov/WaterBalloon/#ISS
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Magical Bubbles & Soap Films – June 8, 2011
Saturday Morning Science - Water in space
Air bubble in a water droplet, resting on a plantlet leaf
Magical Bubbles & Soap Films – June 8, 2011
Saturday Morning Science - Water in space
What happens when gravity becomes negligible?
Water drops
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Magical Bubbles & Soap Films – June 8, 2011
Back on Earth
What happens when a raindrop hits a soap bubble?
… or other intruders?
A summary
http://www.scenicreflections.com/download/208409/Earth_in_Soap_BUBBLE_Wallpaper/
„Physics?
That‘s just an advanced form of playing…“
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The new place:
Freiburg
Freiburg
Fraunhofer Institutefor PhysicalMeasurement TechniquesFreiburg
Thank you!
http://www.scenicreflections.com/download/208409/Earth_in_Soap_BUBBLE_Wallpaper/
See you soon!