Physics on Etsy!

Symmetric Sticks Puzzle

Geometry as art and play-- get this affordable puzzle here:

From Etsy: BUY NOW: Symmetric Sticks Puzzle

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Symmetric Sticks Puzzle: 30 identical pieces, each with two notches as shown, can create 12 interlocking pentagons in a perfect symmetry- look carefully and you can see that each rod is in an identical configuration with the 4 others that connect with it. Precision notches on the rods allow them to interlock with elastic tension such that vector sum of the 4 forces sum to zero in this tensegrity type equilibrium. The dodecahedron, with its 30 edges and 12 sides, is the basis of this puzzle sculpture.

Five Orbiforms: Volumes of Constant Width

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From Etsy: BUY NOW: set of 5 Solids of Constant Width
Use code: FFMPHYSICSFUN to get 25% off from this shop

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Five Orbiforms: precision 3D printed vo5umes of constant width. These shapes have constant diameter no matter their orientation and will roll like spheres between two planes- note how the acrylic plate stays parallel to the table as the sphere and other orbiforms roll underneath. The one that resembles a pyramid is the Meissner tetrahedron, which is conjectured to be the orbiform of least volume. A sphere is the orbiform of maximal volume, and the others are based on revolutions of the Reuleaux triangle, pentagon, and heptagon respectively. Skillfully printed in two colors by Brandon of Fractal Forest Makes. 

Mesmoid Kinetic Object

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From Etsy: BUY NOW: MESMOID Kinetic Object

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Mesmoid Kinetic Object: an elegant physical pendulum for the desk top demonstrates curious periodic motion. The pendulum, precision machined out of weighty polished brass, is a cylinder with an eccentric circle cut out. When set in to motion on the supplied smooth black marble slab, the Mesmoid will rock back and forth for three minutes or so until friction slowly dissipates the kinetic energy and the system comes to rest. The latest in a series of amazing kinetic objects created and designed by physicist and artist Kenneth Brecher. 


Gemstone Chatoyancy: Rays and Stars

Find a variety of polished gemstones with stars and rays here:

From Etsy: BUY NOW: Gemstones: stars and rays

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Gemstone Chatoyancy: illuminating gemstone cabochons reveals rays and stars where light is scattered by microscopic parallel crystal fibers of rutile (titanium oxide) or magnetite that grow within the different mineral species. These fibers grow to be in alignment along the axes of the crystalline structure producing the illuminated rays: 6 point star (synthetic red ruby-aluminum oxide with trace chromium), 4 point star (black diopside- calcium magnesium silicate), and a simple “tiger eye” ray (brown sillimanite- aluminosilicate).

In-Feed Google

Alexandrite Effect

Similar color change gemstones available here:
From Etsy: BUY NOW: Synthetic Alexandrite
Explore propperties of minerals and gemstones with this fun jeweler's flashlight:
From Amazon: BUY NOW: Jeweler's Appraisal Flashlight

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Alexandrite Effect: dramatic color change under different light sources- seen here first under halogen incandescent light and then under cool white LED (similar to sunlight), due to selective absorption of frequencies of visible light. These two faceted crystals are synthetic gems, Tourmalike and Tourmalike+, that dramatically exhibit this effect especially under the illumination of this jeweler’s appraisal lamp that allows one to select white light with different spectra (and also UV). This phenomenon is named for the famous (and expensive) alexandrite gemstone variety of the mineral chrysoberyl.


Magic Portal Illusion V4

Get this version, expertly printed and assembled, here:

From Etsy: BUY NOW: Magic Portal Illusion Desk Toy

Or print it yourself: 3D Print Files: Magic Portal Desk Toy

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Magic Portal Illusion Version 4: the latest update of this new astonishing illusion, now with three separately moving colorful strands that seem to pass in and out of a 4th dimension. The mechanical principle employed is similar to that of a lead screw and slider type actuator, except here translating the slider up and down rotates the helical strands at just the right rate to produce the illusion. Another in a series of amazing 3D print creations by Ada Cohen, expertly printed and assembled by Alex L. Kling. 

Boulliant de Franklin (Hand Boiler) Collection

A variety of shapes and colors are available 
From Educational Innovations: BUY NOW: Hand Boilers 
From Amazon: BUY NOW: Hand Boilers 

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Bouillant de Franklin Collection: my collection of vintage hand boilers, physics toys of blown glass that feature a reversible liquid-gas phase transition and demonstrates the relationship between temperature and pressure in an enclosed volume. The dyed fluid within each is typically dichloromethane which is in both liquid and vapor states. Heat from a hand, or from this catering warming tray, increases pressure in the bottom bulb pushing the liquid to the top bulb. Originally made famous by Benjamin Franklin, the first to describe the physics of its operation. 

Lithophane Color Einstein Portrait

Get a color lithiphane here: (Einstein, or photo of your choice)

From Etsy: BUY NOW: 3D printed full color lithophane

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Lithophane Color Einstein Portrait: in celebration of the great physicist and his monumental discoveries this portrait is a modern take on the lithophane technique from the 1820s- but updated via modern 3D printing to produce full color images through selective absorption and transmission of light. Traditional lithophanes produced gray tone images by shining light through a translucent substance, initially porcelain, where thicker regions absorb the light and appear dark gray, and thinner regions look light gray. 3D printing allows a new method for producing this art form with amazing detail, where layers of colored plastic, applied in the right sequences and thicknesses, can produce lifelike and artistic results. Another amazing 3D print by Alex L. Kling! ➡️


Phonotrope Fluidity

Get these and other amazing phonotrope spinners here:

From Etsy: BUY NOW: Phototrope Animation Spinners 

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Phonotrope Fluidity: more amazing phonotropes from apyrodesign. When the rate of rotation matches the rate of the smartphone video process the six spokes appear to become fluid with waves rippling outward. The precision fabrication of these spinners is specifically designed to interact with the video process, similar to the animation effect of a flip book, but in a repeating cycle like that of the phenakistiscope, the 1833 invention that started moving media animation that lead to the development of movies and video. Swipe to see another design with an illusion of rotating meshed gears.

Septarian Sphere Fluorescence 

Similar mineral carvings available here:

From Etsy: BUY NOW: Phosphorescent Septaria

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

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Septarian Fluorescence: When exposed to long wavelength UV light, this polished sphere of septarian nodule glows brightly like some alien planet. Septarium nodules can be described as a 50+ million year old fossilized mud bubble which contain honey calcite (which fluoresces in pale green), bands of dark brown argonite that glow pale white (with an eerie afterglow from phosphorescence when the UV light is switched off), within a limestone matrix. 

Phase Locking Folk Toy v5.0 

Versions of the Gee Haw Whimmy Diddle available from these sources:

From Etsy: BUY NOW: Hooey Stick Folk Toy

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See the other versions in my collection here: Phase Locking Folk Toys

Phase Locking Folk Toy v5: a final post in this series featuring the “Magic Twin Helicopters” toy that I found in a shop at the Tokyo airport a few years back. A helicopter themed version of the hooey stick, this time with the four rotor blades serving as the propellers. Rubbing the stick over the notches creates both vertical and horizontal vibrations- and leads to a cyclic motion of the struts in the center of each of the propellers, which begin to rotate (with some effort). See previous posts for more info on this folk toy with surprisingly complex physics.


Phase Locking Folk Toy v4.0

Versions of the Gee Haw Whimmy Diddle available from these sources:

From Etsy: BUY NOW: Hooey Stick Folk Toy
Note: this site contains affiliate links for which I may be compensated

See the other versions in my collection here: Phase Locking Folk Toys

Wikipedia has some good details about the Hooey Stick toy


Phase Locking Folk Toy v4: another interesting variation of the “hooey stick” toy in my collection. This one has two rotors both on the same stick- and often they will rotate in opposite directions! (Shown here in slow motion for clarity.) Just as with the regular version of this toy (see yesterday’s post) rubbing the stick over the notches creates vibrations- and can lead to an up and down motion of the shaft in the center of the rotors. The hole in each rotor is larger than the shaft, and when the shaft/notched stick is vibrating it only touches the rotor for a short time each cycle- if the timing is right the stick collides with the rotor such that friction gives it nudge with each vibration to set it spinning- and this can work either clockwise or counterclockwise. Sometimes they spin the same direction and sometimes opposite, which seems to depend on initial conditions and a bit of luck. This version, made in Taiwan, was sold in the 1980s. 

Phase Locking Folk Toy v3.0

Versions of the Gee Haw Whimmy Diddle available from these sources:

From Etsy: BUY NOW: Hooey Stick Folk Toy
Note: this site contains affiliate links for which I may be compensated

See the other versions here: Phase Locking Folk Toys

A detailed physics analysis of this toy was published in 2018 (open acess): Physics of the mechanical toy Gee-Haw Whammy Diddle

Phase Locking Folk Toy v3: spin it left or spin it right, a slight adjustment of the hands produces different results (with a bit of practice) using this modern version of the famous Gee-Haw Wimmy Diddle folk toy. Sometimes also called a Hooey Stick as a demonstrator will often claim that calling out “Gee” makes it spin to the right, or yelling “Haw” will make it spin to the left- which of course is a bunch of hooey! Left and rightward spin shown in 240fps to reduce shutter aliasing.

Ventifact Stone

Specimens aviualable here:

From Etsy: BUY NOW: Ventifact Specimen

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Dreikanter Ventifacts: stones that have been shaped by abrasion of wind blown particles are called ventifacts, often found in desert environments, and dreikanters are a common type of ventifact that shows a characteristic uneven pyramid structure. The shaping of stones this way takes a long time but exact details of this physical process are still an area of active study. Shown here are dreikanter specimens from Patagonia Argentina (black) and Mojave California (dark red) and both feature the characteristic polish and triangular ridges. 


Gravity Drop Challenge

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From Etsy: BUY NOW: Gravity Path Demo Puzzle

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Gravity Drop Challenge: starting at the same height, and ending at a same lower height, which path will take the shortest amount of time? The straight line (red marble) or the wavy longer path (blue marble)? The weird thing is that both marbles will have identical speeds at the finish line- yet one gets there quicker. The physics problem of finding the curve of fastest descent is called the brachistochrone problem- from the Greek words brakhistos ‘shortest’ and khronos ‘time’- and it is not a straight line. The fastest curve turns out to be the cycloid- a topic for a future post.

Aperiodic Monotile

Learn more about this recent math dicovery here: An aperiodic monotile (arXiv)

Althogh the math says they can tile the plane, getting them to do so is more challenging than one might think! 
Get a set of laser cut hat tiles here:
From Etsy: BUY NOW: "the Hat" monotile set

See other aperoidic tilings in my collection.

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Aperiodic Monotile: this newly discovered 13 sided shape, named “the hat”, will tessellate a plane to infinity, similar to how squares or hexagons can tile out with no gaps. However the hat tiles the plane aperiodically- if one tries to shift a part of a hat tiling, the shifted part will not align or match up with any other part of the same tiling- all the way out to infinity! The fact that aperiodic tessellations exist at all is pretty amazing, and Sir Roger Penrose (Nobel prize in physics 2020) is also famous for discovering a pair of regularly shaped polygons that tile in this aperiodic way. However it was not clear until a few weeks ago if a single shaped tile could tessellate aperiodically when the hat was described in a paper by Smith, Myers, Kaplan, and Goodman-Strauss uploaded to arXiv March 20. 

Symmetry Sculptures

These amazing scluptures from Bathesheba Grossman available here:

From Etsy: BUY NOW: Math Sculptures

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Symmetry Sculptures: the Quintrino with 12 identical interlocking starfish, and the Metatrino with 6 identical connected four armed stars- based on the symmetries of the dodecahedron and the cube. Two examples of the amazing work of artist Bathsheba Grossman, a pioneer in creating such intricate mathematical forms.