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Catenary Curve

Get this scale model here: 
From eBay: BUY NOW Scale Gateway Arch 

Learn about the sunshield of the James Webb Space Telescope here:
SmarterEveryDay: Episode 270: JWST Sunshield

Click this link for more catenary curve fun!

Catenary Curve: What do the James Webb Space Telescope and the Gateway Arch have in common? The 5 sunshield panels of the JWST are engineered to be pulled into shape by the geometry of the catenary curve (see the latest video from SmarterEveryDay for amazing details on this). The Gateway arch is perhaps the most iconic use of this engineering principle and it matches the shape of a chain hanging from two ends, a curve known as the catenary or hyperbolic cosine- demonstrated here with a scale model souvenir (1”=100’). When an arch is built in the shape of this special mathematical curve the compression forces between each segment are always parallel to the curve- the arch is stable with no tendency to buckle. Famously used in design from the buttresses of Notre Dame to the Gateway Arch, and now in orbit about the Earth-Sun L2 point! 

Vintage Blacklight Poster: Escher

Fun vintage posters can be found here: 

From eBay: BUY NOW: Blacklight Poster Escher

From Etsy: BUY NOW: Blacklight Poster Escher

Vintage Blacklight Poster: a stunning psychedelic era poster from 1971 glows brightly under a vintage blacklight from the same year. This amazing silkscreen uses fluorescent pigments (new tech in the 1960s) that absorb ultraviolet light and then re-emit the energy in visible photons. Design based on M. C. Escher’s black and white 1952 wood engraving print “Dragon”. 

Anti-Gravity Puzzle

This particular puzzle by is no longer in production.

However (spoiler), it's possible to creat a version of this puzzle with these: 
From Educational Innovations: BUY NOW Growing Spheres 

"Anti-Gravity" Puzzle: a physics brain teaser- what's the trick here? Four glass marbles can move but stay separated in this liquid filled tube no matter the orientation- why do they not touch? 


Vortices in a Kalliroscope

Vintage (1970s) Kalliroscopes are sometimes available here: 
From eBay: Search NOW Kalliroscopes 

Click this linkfor the best Kalliroscope currently in production and available.

Vortices in a Kalliroscope: rheoscopic fluid reveals the intricate and beautiful turbulence induced in an enclosed fluid by rotation of the container. The initial acceleration of the fluid during initial spin-up is shown here in 240fps slow motion. Invented and produced by artist and inventor Paul Matisse in the 1970s, suspended microscopic flat crystals of guanine reflect light and allow visualization of the fluid's motion. This rheoscopic fluid is special in that the guanine crystals are the same density as the tetrachloroethylene liquid so the crystals never settle to the bottom making the fluid reactive to showing the slightest movement. 

Polage Miniatures

Austine has an on-line gallery of her amazing work.
From Austine Studios: BUY NOW: Polarized Light Art 

click here for more physics fun with polarization. 

Here is a very nice discussion about polarization that pertains to Polage: Experiments With Polarized Light by Donald E. Simanek 

Polage Miniatures: art with polarized light using polarizing sheets and birefringent cellophane to create changing forms and colors. Rotation of the polarizing filter allows the artist to produce colorful metamorphosis. These affordable sun catchers were created by Austine Wood Comarow (the main developer of this art form), and look amazing through polarized sunglasses as well. Light as a transverse wave has an orientation, denoted as polarization, and a polarizing filter can be used to block certain orientations. The colors in polage come from how the molecular structure of plastics can rotate the polarization of any light that passes through- but only light corresponding to yellows and greens gets rotated in plastic, reds and blues not so much. Polage uses different layers of plastic to rotate the light, and then polarizing filters are added to allow only certain frequencies (colors) of light through.

Heat Pipe

The heat pipe kit includes the pipe and a copper rod: 
From Educational Innovations: BUY NOW Heat Pipe Demo Kit 

Get a heat pipe here (various sizes and shapes):
From Amazon: BUY NOW: Heat Pipe

Here is the liquid crystal sheet used in the video (range 20-25C): 
From Educational Innovations: BUY NOW liquid crystal thermometer sheet 

Heat Pipe: a device that transfers heat with great efficiency- as demonstrated by this fantastic kit from @educational_innovations . Here a liquid crystal goes from green (room temp) to black (near freezing) showing the heat transfer to a piece of ice through a heat pipe (top) and a similar sized piece of solid copper rod (bottom). As you can see the heat pipe cools much faster than the copper rod even though copper is an excellent conductor of heat. The heat pipe is a thin shell of copper that surrounds a tube of sponge like material filled with some water vapor and sealed with a low pressure inside. The heat is transferred from one end to the other by the phase transition of water- at the warm end water in the sponge evaporates into vapor absorbing heat energy, the vapor travels down the hollow core to the cold end where it condenses into liquid releasing heat energy. The water is wicked by the sponge to the warm end and the process repeats. Heat pipes like this one pull heat away from the CPUs in modern computers preventing them from melting. The amazing heat transfer ability is clearly felt in the fingertips if one places the copper rod and heat pipe into a glass of ice water-the heat pipe immediately gets cold! 

Mirror Illusion Motion Bank

This vitage device urrently available on eBay, and similar mirror illusion banks: 

From eBay: BUY NOW: Mirror Illusion Bank

Mirror Illusion Spacecraft Bank: Symmetry + Reflection = Illusion. Deposit a coin (which seems to vanish) and a spacecraft of some sort states to revolve within a silver ring seemingly suspended in space. The symmetry of the ring and craft allows a half of these objects to appear as a whole, and a AA battery powers a motor which drives gears to slowly spin the portion of the mirror inside the ring (with the spacecraft attached). The best version of the mirror illusion box I’ve seen.


Top Secret

This physics toy top is available here: 

From Amazon: BUY NOW Mystery Spinning Top

From eBay: BUY NOW Mystery Spinning Top 

The amazing green magnetic viewing film is also available: 
From Educational Innovations: BUY NOW Magnetic Field Viewing Film 

Here is the 1974 patent showing the very simple circuit of this device. The spinning dipole (the top itself) induces a current in one of the coils, and this current is fed to the base of the transistor turning the electromagnet on when the top is near. 

"Top Secret": this top will stay spinning for more than a week- because it is actually a motor! The top is a dipole magnet (as revealed by Magneview film) and the base has an electromagnet that gives the dipole a push when the top comes near the center. An ingeniously simple circuit consisting of only a battery, a coil, and a transistor, is activated when the spinning magnet nears the coil turning on the electromagnet to give a boost to the spin of the magnetic top.

Magnetic Tensegrity Table

Available here:

From BUY NOW: Magnetic Tensegrity Table

See similar scupltures here: Tensegrity on @physicsfun

Folow this link for Mova kinetic globes:  Mova Globes- Earth and Planets

Magnetic Tensegrity Table: This CNC machined tensegrity sculpture replaces the center tension member (chain) with a pair of attracting neodymium magnets. Made from 6061 aluminum and nickel plated steel chain, the “Impossible Table” is the creation of Kevin Sayers of The table can support up to about a kilogram of mass, and makes for a nice display stand for my Mova globe of Pluto (swipe to view). Another fun configuration of the tensegrity concept, invented by Kenneth Snelson and made famous by the architect Buckminster Fuller in 1949. 


Get one here: 
From Mindsets: BUY NOW Copy Coder 

Copycoder: clever use of an array of cylindrical lenses to scramble and unscramble large font messages- a modern "secret code" toy. The refractive optics invert slivers of an image to encode or decode it. You can scramble an image by photocopying a message covered with the array plate, or go to and a program will scramble a message that you can print out to send to anyone that also has the lens array. Invented by Steve Ostler from the UK. Fun! 

Bismuth Diamagnetic Trap Levitation

See more of Ernie's amazing creations here in his Etsy shop Element83 
From Etsy: BUY NOW Magnetic Levitation Sculptures

From Etsy: BUY NOW: Bismuth Maglev Rod

Bismuth Diamagnetic Trap Levitation: neodymium cube magnet trapped between two pieces of strongly diamagnetic bismuth crystal. Diamagnetic substances only have magnetic fields of their own when placed in an external magnetic field from another source- here the cube shaped magnet supplies the field. Diamagnetic fields are pretty weak though so two large ceramic magnets are placed on each side and adjusted to help lift the cube magnet against gravity. Trapped in equilibrium by these magnetic fields, the slightest air currents can send the cube magnet dancing. Swipe to see a vertical trap based on the same physics. More amazing creations by Ernie McElhannon.

Memory Spring

Available here: 
From Mindsets: BUY NOW 
Memory Springs 

Affordable samples and kits here:
From Educational Innovations: BUY NOW: Energy Wire 

Similar produces featuring Nitinol Memory Wire: 
From Amazon: BUY NOW 
Nitinol Memory Wire Kits 

Memory Spring: some special alloys of brass can be made to have a shape memory triggered by temperature. These springs quickly change their length from 1 cm to 2.5cm when heated above 90 C (done here with hot water) and just as quickly shrink back to original size when cooled (immersed in cold water). Useful in many applications, especially things like automatic fire sprinkler valves and thermostats in car engines. This amazing property is related to a solid state phase transition similar to that of Nitinol wire called a Martensitic transformation.

Squaring a Circle Sculpture

This sculpture available as a 3D print:

From ShapeWays: BUY NOW: Square Circle Illusion

See other amazing geometric illusions here: Ambiguous Objects

Squaring a Circle: from one particular point of view this wireframe sculpture looks like a circle, from another it’s a square! From other viewing angles one can see that the underlying curve is comprised of four identical segments of a parabola. A wonderful example of how a single perspective can be misleading! A math sculpture available as a 3D print by Matt Enlow. 

Perspective Puzzle

Vintage puzzles in this series are sometimes available on eBay: 
From eBay: Search NOW Virtual Illusion 3D Puzzle

Perspective Puzzle: ten flat images, when ordered and spaced correctly, combine to produce this 3D illusion of structure and depth. This vintage toy by Mattel was sold as “Virtual Illusion 3D Puzzle” where the challenge is to scramble/shuffle the 12 sheets and then place them in the correct orientation and order to complete the image. A fun application of the math and physics of anamorphosis and perspective. 

Carved Heart Minerals that Glow

Similar mineral carvings available here:

From Etsy: BUY NOW: Fluorescent Pink Calcite Heart

From Etsy: BUY NOW: Phosphorescent Septaria Heart

You will also want an awesome UV flashlight like this one:
From Amazon: BUY NOW: High Power UV Light

Ultraviolet Valentines: carved from natural minerals these hearts glow with bright fluorescence and (swipe) an afterglow of phosphorescence. When exposed to long wavelength UV light, the pink calcite heart converts the ultraviolet energy into photons of bright red light. The two smaller hearts (swipe) are carved from septarian nodules with honey calcite which fluoresces in pale green, and bands of dark brown argonite which surprisingly glow pale white with an eerie afterglow from phosphorescence when the UV light is switched off. 

Ultimate Solid of Constant Width

Available in three metals and two finishes.
From The Matter Collection: 
Order NOW: Ultimate Solid of Constant Width- Brass
Order NOW: Ultimate Solid of Constant Width- Steel
Order NOW: Ultimate Solid of Constant Width- Copper

Ultimate Solid of Constant Width: Reuleaux tetrahedrons with specially calculated curved edges become volumes of constant width- possibly the minimum volume that can possess this property. The shape featured here is a new discovery of a solid of constant width that has perfect tetrahedral symmetry. Made from solid steel, brass, and copper- these shapes have constant diameter no matter their orientation and will roll like spheres between two planes- note how the acrylic plate remains parallel to the desktop as the orbiforms roll in between. Currently available on Kickstarter from my friends at the Matter Collection : Reuleaux tetrahedrons with specially calculated curved edges become volumes of constant width- possibly the minimum volume that can possess this property. The shape featured here is a recent discovery of a solid of constant width that has perfect tetrahedral symmetry. Made from solid steel, brass, and copper- these shapes have constant diameter no matter their orientation and will roll like spheres between two planes- note how the acrylic plate remains parallel to the desktop as the orbiforms roll in between. Currently available from my friends at the Matter Collection