![Soapbubbles1b](https://upload.wikimedia.org/wikipedia/commons/e/e3/Soapbubbles1b.jpg)
A soap bubble is an extremely thin
film
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...
of
soap
Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...
or
detergent
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...
and water enclosing air that forms a hollow
sphere
A sphere () is a Geometry, geometrical object that is a solid geometry, three-dimensional analogue to a two-dimensional circle. A sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...
with an
iridescent
Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...
surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. They are often used for children's enjoyment, but they are also used in artistic
performance
A performance is an act of staging or presenting a play, concert, or other form of entertainment. It is also defined as the action or process of carrying out or accomplishing an action, task, or function.
Management science
In the work place ...
s. Assembling many bubbles results in
foam
Foams are materials formed by trapping pockets of gas in a liquid or solid.
A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...
.
When light shines onto a bubble it appears to change colour. Unlike those seen in a rainbow, which arise from differential refraction, the colours seen in a soap bubble arise from light
wave interference
In physics, interference is a phenomenon in which two waves combine by adding their displacement together at every single point in space and time, to form a resultant wave of greater, lower, or the same amplitude. Constructive and destructive ...
, reflecting off the front and back surfaces of the thin soap film. Depending on the thickness of the film, different colours interfere constructively and destructively.
Mathematics
Soap bubbles are physical examples of the complex
math
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
ematical problem of
minimal surface
In mathematics, a minimal surface is a surface that locally minimizes its area. This is equivalent to having zero mean curvature (see definitions below).
The term "minimal surface" is used because these surfaces originally arose as surfaces that ...
. They will assume the shape of least
surface area
The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc ...
possible containing a given volume. A true minimal surface is more properly illustrated by a
soap film
Soap films are thin layers of liquid (usually water-based) surrounded by air. For example, if two soap bubbles come into contact, they merge and a thin film is created in between. Thus, foams are composed of a network of films connected by Platea ...
, which has equal pressure on both sides, becoming a surface with zero
mean curvature In mathematics, the mean curvature H of a surface S is an ''extrinsic'' measure of curvature that comes from differential geometry and that locally describes the curvature of an embedded surface in some ambient space such as Euclidean space.
The ...
. A soap bubble is a closed soap film: due to the difference in outside and inside pressure, it is a surface of ''constant'' mean curvature.
While it has been known since 1884 that a spherical soap bubble is the least-area way of enclosing a given volume of air (a theorem of
H. A. Schwarz
Karl Hermann Amandus Schwarz (; 25 January 1843 – 30 November 1921) was a German mathematician, known for his work in complex analysis.
Life
Schwarz was born in Hermsdorf, Silesia (now Jerzmanowa, Poland). In 1868 he married Marie Kummer, ...
), it was not until 2000 that it was proven that two merged soap bubbles provide the optimum way of enclosing two given volumes of air of different size with the least surface area. This has been dubbed the ''
double bubble conjecture
In the mathematical theory of minimal surfaces, the double bubble theorem states that the shape that encloses and separates two given volumes and has the minimum possible surface area is a ''standard double bubble'': three spherical surfaces meet ...
''.
Because of these qualities, soap bubble films have been used in practical problem solving applications.
Structural engineer
Structural engineers analyze, design, plan, and research structural components and structural systems to achieve design goals and ensure the safety and comfort of users or occupants. Their work takes account mainly of safety, technical, economic ...
Frei Otto
Frei Paul Otto (; 31 May 1925 – 9 March 2015) was a German architect and structural engineer noted for his use of lightweight structures, in particular tensile and membrane structures, including the roof of the Olympic Stadium in Munich for ...
used soap bubble films to determine the geometry of a sheet of least surface area that spreads between several points, and translated this geometry into revolutionary
tensile roof structures. A famous example is his West German Pavilion at Expo 67 in Montreal.
Physics
Merging
![Ggb in soap bubble 1](https://upload.wikimedia.org/wikipedia/commons/1/1f/Ggb_in_soap_bubble_1.jpg)
When two bubbles merge, they adopt a shape which makes the sum of their surface areas as small as possible, compatible with the volume of air each bubble encloses. If the bubbles are of equal size, their common wall is flat. If they aren't the same size, their common wall bulges into the larger bubble, since the smaller one has a higher internal
pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
than the larger one, as predicted by the
Young–Laplace equation
In physics, the Young–Laplace equation () is an algebraic equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or ...
.
At a point where three or more bubbles meet, they sort themselves out so that only three bubble walls meet along a line. Since the surface tension is the same in each of the three surfaces, the three angles between them must be equal to 120°. Only four bubble walls can meet at a point, with the lines where triplets of bubble walls meet separated by cos
−1(−1/3) ≈ 109.47°. All these rules, known as
Plateau's laws
Plateau's laws describe the structure of soap films. These laws were formulated in the 19th century by the Belgian physicist Joseph Plateau from his experimental observations. Many patterns in nature are based on foams obeying these laws.
Laws f ...
, determine how a
foam
Foams are materials formed by trapping pockets of gas in a liquid or solid.
A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...
is built from bubbles.
Stability
The longevity of a soap bubble is limited by the ease of rupture of the very thin layer of water which constitutes its surface, namely a
micrometer Micrometer can mean:
* Micrometer (device), used for accurate measurements by means of a calibrated screw
* American spelling of micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; ...
-thick
soap film
Soap films are thin layers of liquid (usually water-based) surrounded by air. For example, if two soap bubbles come into contact, they merge and a thin film is created in between. Thus, foams are composed of a network of films connected by Platea ...
.
It is thus sensitive to :
* Drainage within the soap film: water falls down due to gravity. This can be slowed by increasing the water viscosity, for instance by adding glycerol. Still, there is an ultimate height limit, which is the
capillary length
The capillary length or capillary constant, is a length scaling factor that relates gravity and surface tension. It is a fundamental physical property that governs the behavior of menisci, and is found when body forces (gravity) and surface forces ...
, very high for soap bubbles: around 13 feet (4 meters). In principle, there is no limit in the length it can reach.
*
Evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
: This can be slowed by blowing bubbles in a wet atmosphere, or by adding some sugar to the water.
* Dirt and fat: When the bubble touches the ground, a wall, or our skin, it usually ruptures the soap film. This can be prevented by wetting these surfaces with water (preferably containing some soap).
After experiments, researchers found that a solution containing:
* 85.9 % water
* 10 %
glycerol
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
* 4 %
washing-up liquid
Dishwashing liquid (or washing-up liquid in British English), also known as dishwashing soap, dish detergent, and dish soap is a detergent used to assist in dishwashing. It is usually a highly-foaming mixture of surfactants with low skin irri ...
* 0.1 %
guar gum
Guar gum, also called guaran, is a galactomannan polysaccharide extracted from guar beans that has thickening and stabilizing properties useful in food, feed, and industrial applications. The guar seeds are mechanically dehusked, hydrated, mil ...
gave the longest lasting results as it minimised the
Marangoni Effect
The Marangoni effect (also called the Gibbs–Marangoni effect) is the mass transfer along an interface between two phases due to a gradient of the surface tension. In the case of temperature dependence, this phenomenon may be called thermo-capill ...
.
Wetting
![Bubble on a liquid surface](https://upload.wikimedia.org/wikipedia/commons/f/f4/Bubble_on_a_liquid_surface.jpg)
When a soap bubble is in contact with a solid or a liquid surface
wetting
Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with th ...
is observed. On a solid surface, the
contact angle
The contact angle is the angle, conventionally measured through the liquid, where a liquid–vapor interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation. A given system of solid, liq ...
of the bubble depends on the
surface energy
In surface science, surface free energy (also interfacial free energy or surface energy) quantifies the disruption of intermolecular bonds that occurs when a surface is created. In solid-state physics, surfaces must be intrinsically less energe ...
of the solid., A soap bubble has a larger contact angle on a solid surface displaying
ultrahydrophobicity
Ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°. This is also referred to as the lotus effect, after the ...
than on a hydrophilic surface – see
Wetting
Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with th ...
. On a liquid surface, the contact angle of the soap bubble depends on its size - smaller bubbles have lower contact angles.
Medicine
Contact dermatitis
The composition of soap bubbles' liquid has many recipes with slightly different ingredients. The most common one contains:
* 2/3 cup of dishwashing
soap
Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...
* 1 gallon of water
* 2/3 tablespoon of
glycerol
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
Because of the presence of dishwasher soap, it is not uncommon for children to develop
dermatitis
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...
on their face or hands with consequences such as rashes, swelling of the eyes, vomiting and dizziness.
Soap bubbles as unconventional computing
The structures that soap films make can not just be enclosed as spheres, but virtually any shape, for example in wire frames. Therefore, many different minimal surfaces can be designed. It is actually sometimes easier to physically make them than to compute them by
mathematical modelling
A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in the natural sciences (such as physics, b ...
. This is why the soap films can be considered as
analog computer
An analog computer or analogue computer is a type of computer that uses the continuous variation aspect of physical phenomena such as electrical, mechanical, or hydraulic quantities (''analog signals'') to model the problem being solved. In c ...
s which can outperform conventional computers, depending on the complexity of the system.
Bubbles in education
Bubbles can be effectively used to teach and explore a wide variety of concepts to even young children. Flexibility, colour formation, reflective or mirrored surfaces, concave and convex surfaces, transparency, a variety of shapes (circle, square, triangle, sphere, cube, tetrahedron, hexagon), elastic properties, and comparative sizing, as well as the more esoteric properties of bubbles listed on this page. Bubbles are useful in teaching concepts starting from 2 years old and into college years. A Swiss university professor, Dr. Natalie Hartzell, has theorized that the usage of artificial bubbles for entertainment purposes of young children has shown a positive effect in the region of the child's brain that controls motor skills and is responsible for coordination with children exposed to bubbles at a young age showing measurably better motion skills than those who were not.
Recreation
Use in play
![Bubble Blowing Delores Park Dyke March June 2019](https://upload.wikimedia.org/wikipedia/commons/f/fe/Bubble_Blowing_Delores_Park_Dyke_March_June_2019.jpg)
![Jean-Baptiste Siméon Chardin 022](https://upload.wikimedia.org/wikipedia/commons/4/4a/Jean-Baptiste_Sim%C3%A9on_Chardin_022.jpg)
Soap bubbles have been used as entertainment for at least 400 years, as evidenced by 17th-century Flemish paintings showing children blowing bubbles with clay pipes. The London-based firm
A. & F. Pears created a famous advertising campaign for its soaps in 1886 using a painting by John Everett Millais of a child playing with bubbles. The Chicago company Chemtoy began selling bubble solution in the 1940s, and bubble solution has been popular with children ever since. According to one industry estimate, retailers sell around 200 million bottles annually.
Colored bubbles
A bubble is made of transparent water enclosing transparent air. However, the
soap film
Soap films are thin layers of liquid (usually water-based) surrounded by air. For example, if two soap bubbles come into contact, they merge and a thin film is created in between. Thus, foams are composed of a network of films connected by Platea ...
is as thin as the visible light
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...
, resulting in
interferences. This creates
iridescence
Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...
which, together with the bubble's spherical shape and fragility, contributes to its magical effect on children and adults alike. Each colour is the result of varying thicknesses of soap bubble film.
Tom Noddy (who featured in the second episode of
Marcus du Sautoy
Marcus Peter Francis du Sautoy (; born 26 August 1965) is a British mathematician, Simonyi Professor for the Public Understanding of Science at the University of Oxford, Fellow of New College, Oxford and author of popular mathematics and popu ...
's ''
The Code'') gave the analogy of looking at a
contour
Contour may refer to:
* Contour (linguistics), a phonetic sound
* Pitch contour
* Contour (camera system), a 3D digital camera system
* Contour, the KDE Plasma 4 interface for tablet devices
* Contour line, a curve along which the function has a ...
map of the bubbles' surface. However, it has become a challenge to produce artificially coloured bubbles.
Byron, Melody & Enoch Swetland invented a patented non-toxic bubble (Tekno Bubbles) that glow under UV lighting. These bubbles look like ordinary high quality "clear" bubbles under normal lighting, but glow when exposed to true UV light. The brighter the UV lighting, the brighter they glow. The family sold them worldwide, but has since sold their company.
Adding coloured
dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
to bubble mixtures fails to produce coloured bubbles, because the dye attaches to the water molecules as opposed to the surfactant. Therefore, a colourless bubble forms with the dye falling to a point at the base. Dye
chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...
Dr. Ram Sabnis has developed a
lactone
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring.
Lactones are formed by intramolecular esterification of the co ...
dye that sticks to the surfactants, enabling brightly coloured bubbles to be formed.
Crystal violet lactone
Crystal violet lactone (CVL) is a leuco dye, a lactone derivate of crystal violet 10B. In pure state it is a slightly yellowish crystalline powder, soluble in nonpolar or slightly polar organic solvents.
The central carbon in the leuco form is i ...
is an example. Another man named Tim Kehoe invented a coloured bubble which loses its colour when exposed to pressure or oxygen, which he is now marketing online as
Zubbles
Zubbles is a commercial name for colored soap bubbles. Zubbles claim to fame is that they are the first colored soap bubbles that do not leave stains. Instead they fade away with exposure to air, pressure, and water.
''Popular Science'' named Zu ...
, which are non-toxic and non-staining. In 2010, Japanese astronaut
Naoko Yamazaki
is a Japanese engineer and former astronaut at JAXA. She was the second Japanese woman to fly in space. The first was Chiaki Mukai.
Early life
Yamazaki was born Naoko Sumino in Matsudo City. She spent two years of her childhood in Sapporo. Af ...
demonstrated that it is possible to create coloured bubbles in
microgravity
The term micro-g environment (also μg, often referred to by the term microgravity) is more or less synonymous with the terms ''weightlessness'' and ''zero-g'', but emphasising that g-forces are never exactly zero—just very small (on the I ...
. The reason is that the water molecules are spread evenly around the bubble in the low-gravity environment.
Freezing
![Frozen Ice Bubble](https://upload.wikimedia.org/wikipedia/commons/8/80/Frozen_Ice_Bubble.jpg)
If soap bubbles are blown into air that is below a
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
of , they will freeze when they
touch a surface. The air inside will gradually
diffuse
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
out, causing the bubble to crumble under its own weight. At temperatures below about , bubbles will freeze in the air and may shatter when hitting the ground. When a bubble is blown with warm air, the bubble will freeze to an almost perfect sphere at first, but when the warm air cools, and a reduction in volume occurs, there will be a partial collapse of the bubble. A bubble, created successfully at this low temperature, will always be rather small; it will freeze quickly and will shatter if increased further.
Freezing of small soap bubbles happens within 2 seconds after setting on snow (at air temperature around –10...–14 °C).
[pilleuspulcher]
Freezing soap bubbles on snow
google+, Regensburg, Germany, 23 January 2017, retrieved 25 January 2017. – Photos, description in German.
Art
![Szappanbuborék - Alex, Deák tér (1)](https://upload.wikimedia.org/wikipedia/commons/e/ee/Szappanbubor%C3%A9k_-_Alex%2C_De%C3%A1k_t%C3%A9r_%281%29.JPG)
Soap bubble
performance
A performance is an act of staging or presenting a play, concert, or other form of entertainment. It is also defined as the action or process of carrying out or accomplishing an action, task, or function.
Management science
In the work place ...
s combine
entertainment
Entertainment is a form of activity that holds the attention and interest of an audience or gives pleasure and delight. It can be an idea or a task, but is more likely to be one of the activities or events that have developed over thousa ...
with artistic achievement. They require a high degree of skill. Some performers use common commercially available bubble liquids while others compose their own solutions. Some artists create giant bubbles or tubes, often enveloping objects or even humans. Others manage to create bubbles forming cubes, tetrahedra and other shapes and forms. Bubbles are sometimes handled with bare hands. To add to the visual experience, they are sometimes filled with
smoke
Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product ...
, vapour or
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
and combined with
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...
lights or fire. Soap bubbles can be filled with a flammable gas such as
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
and then ignited.
See also
*
Antibubble
An antibubble is a droplet of liquid surrounded by a thin film of gas, as opposed to a gas bubble, which is a sphere of gas surrounded by a liquid. Antibubbles are formed when liquid drops or flows turbulently into the same or another liquid. ...
*
Bubble pipe
A bubble pipe is a toy shaped like a tobacco pipe, intended to be used for blowing soap bubbles.
Design
Bubble pipes are one of the original bubble toys, Most bubble pipes are made of plastic and therefore cannot be used for actual smoking. ...
*
Foam
Foams are materials formed by trapping pockets of gas in a liquid or solid.
A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...
*
Joseph Plateau
Joseph Antoine Ferdinand Plateau (14 October 1801 – 15 September 1883) was a Belgian physicist and mathematician. He was one of the first people to demonstrate the illusion of a moving image. To do this, he used counterrotating disks with repea ...
*
Stretched grid method
The stretched grid method (SGM) is a numerical technique for finding approximate solutions of various mathematical and engineering problems that can be related to an elastic grid behavior.
In particular, meteorologists use the stretched grid meth ...
*
Tom Noddy
*
Weaire–Phelan structure
In geometry, the Weaire–Phelan structure is a three-dimensional structure representing an idealised foam of equal-sized bubbles, with two different shapes. In 1993, Denis Weaire and Robert Phelan found that this structure was a better solution ...
References
Further reading
* Oprea, John (2000). ''The Mathematics of Soap Films – Explorations with Maple''. American Mathematical Society (1st ed.).
* Boys, C. V. (1890) ''Soap-Bubbles and the Forces that Mould Them''; (Dover reprint) . Classic Victorian exposition, based on a series of lectures originally delivered "before a juvenile audience".
*
Isenberg, Cyril (1992) ''The Science of Soap Films and Soap Bubbles ''; (Dover) .
* Noddy, Tom (1982) "Tom Noddy's Bubble Magic" Pioneer bubble performer's explanations created the modern performance art.
* Stein, David (2005) "How to Make Monstrous, Huge, Unbelievably Big Bubbles"; (Klutz) Formerly "The Unbelievable Bubble Book" (1987) it started the giant bubble sport.
External links
International Awarded Bubble ShowGallery of Macro Photographs of bubbles to create photographic art workVideos of Bubble and Droplet InteractionsPerformances with bubbles and giant bubbles
{{DEFAULTSORT:Soap Bubble
Fluid dynamics
Minimal surfaces
Bubbles (physics)
Physical activity and dexterity toys