Our friends stopped by with a simple apparatus to demonstrate the diamagnetic properties of bismuth metal. Diamagnetism is a extremely weak magnetic effect — generally orders of magnitude weaker than everyday permanent magnets, which exhibit ferromagnetism. However it is also an extremely interesting effect because diamagnetic materials are repelled by magnetic fields. This is different than the case with ferromagnets, where one pole of a magnet repels another — rather, the entire material is (weakly) repelled by any magnetic pole.
Now, how might one observe such a weak effect? One way is to build a magnetic levitation rig, but the field configurations there are a little less obvious. With a simple but sensitive balance, we can see the repulsion directly. The balance above has a long wooden beam, a central pivot on two blocks of plastic, and a couple of coins on the far end for counterbalance.
At the business end of the scale, there is a cylinder of bismuth metal about 1 cm in diameter, held in place by a rubber band. We also have a larger rectangular block, which is our test magnet, made of grade N50 NdFeB and painted black. And finally, the Lego Astronaut Twins are here helping out as a scale and position reference.
Moving the block magnet beneath the bismuth, we can see what happens in an animated GIF:
After the balance settles, the resting position of the end with the bismuth is considerably higher. With some calibration in terms of weights and/or positions, one could even measure the exerted force with some precision.
A slight improvement to this apparatus would be to reverse the roles of the bismuth and the block magnet. That is, to affix the magnet to the arm of the balance, and to slide the bismuth beneath it instead. You could then use a nearby block of aluminum to damp the motion of the beam through magnetic (eddy current) damping. Many commercial balance-beam type scales already use magnetic damping so that they settle down to their final values faster.
In modern times, our contemporary Maker and Maker education movements have helped to rekindle our cultural interest in hands-on education, especially in the STEM and STEAM fields, in a way that hasn’t been seen since the 1960s — which is why it’s such a good time to bring this book back.
Coming soon: The Annotated Build-It-Yourself Science Laboratory is a new, updated version of Build-It-Yourself Science Laboratory, the classic 1960’s hands-on science book by Raymond E. Barrett.
The book is scheduled to make its debut at Maker Faire next week, where I’ll be speaking about it. It’s also available for pre-order now from Amazon.com and other sellers of books, as well as from our store.
We’ll be writing much more about the book once it’s out— about what’s in the book, the process of updating and annotating it, and about the hundreds of project ideas spanning biology, geology, chemistry, physics and more.
However, since we’re already in teaser mode, here are some photos of the original version from the 1960’s:
Fine print: “You can build these and many other experimental items with materials from your home, garage, or local hardware store. Build-It-Yourself Science Laboratory will show you how!”
For each of the last two years, we’ve released sets of “Download and Print” cards for Valentine’s day. The 2013 set had six equation-heavy cards, and the 2014 set was a set of six symbol-heavy cards. This year, we’re releasing six new cards, bringing the collection up to a total of 18 cards. This year’s new cards feature love, hearts, and arrows (but no bows or cupids):
For when your love is complex, but not whatsoever imaginary.
For that moment when you want to express that not only is the first derivative of your love positive, but so is the second.
(Just in case there was a danger of none of these being sufficiently cheesy.)
Not sure how we missed this one in last year’s set of symbols. Alternate caption: “You light up my life.”
And what better way to say “I love you,” than with the gift of a math problem?
You can download the full set here, which includes all 18 designs from the three years (a 765 kB .PDF document).
As usual, print them out on (or otherwise affix to) card stock, and [some steps omitted] enjoy the resulting lifelong romance.
Update:New cards have been released! Please check out the 2016 set, which contains all 24 cards from 2013 through 2016.
The Hill Country Science Mill is celebrating its grand opening on February 14th. It’s a new science center in Johnson City, Texas housed in a historic feed mill built in 1880 as a steam grist mill and cotton gin. This picture of their WaterColorBot is from a preview day in November. A “Fall in Love with Science” event sounds like a great way to celebrate Valentine’s Day!
The upcoming lunar eclipse on Wednesday morning will offer a rare possibility for some viewers: a selenelion. Some locations (east of the Mississipi) may be able to see the setting eclipsed moon and the rising sun at the same time. But wait, it’s an eclipse, so that means that the sun and moon are on opposite sides of the earth, right? Right. So you shouldn’t be able to see them at the same time, right? Wrong. The earth’s atmosphere refracts the light from both, letting you see the sunrise a little early, and the moonset for a little longer. A guide to what part of the eclipse will be in progress at sunrise at various locations is available at space.com. You might just want to get up before sunrise for this one!
There are culturally common activities like wine and cheese tastings that explore variations of a particular theme. There are also flavor tripping parties specifically for trying out the taste bud altering miracle fruit. And there are molecular gastronomy and modernist cuisine that are intended challenge your expectations of texture and flavor. In the spirit of these kinds of experiences, we came up with a wide-ranging set of interesting (and sometimes challenging) items that can be shipped through the mail and shared between internet friends.
The goals of the project include isolating a few interesting flavors that are not normally tasted on their own, understanding a bit about the ways that shape and texture affect flavor, and play a bit with some of the available “mouth altering” spices and flavors.
Most of the items we included in our tasting kit are from Indian or asian grocery stores. For herbs and spices, getting them from a shop with high turnover will help in obtaining fresher spices that are more full of flavor. They’re also likely to be less expensive at places that expect larger quantities of spices to be used in foods (we’ve written about this before). Ethnic groceries are better at this than mainstream ones, and places with bulk bins can be just about the worst. A few items we shopped for online, and a couple came from our garden.
For tasting order, we opted to start with more subtle flavors and end with mouth-altering ones. Our general itinerary was divided into four parts: flavors & scents, shapes, adventures, and light.
Of special note: many people are sensitive to particular (and sometimes esoteric) food items. Be sure you have discussed food allergies with all participants before plying them with unknown ingredients. Decide if you want to try things before announcing what they are. Have water and neutral flavored crackers or bread for cleansing the palette between flavors as needed or desired.
One of the joys of life is introducing people to new flavors and textures that you love, whether they are from your own kitchen or your favorite restaurant. Every so often, that will backfire, when someone ends up not liking your beloved dish. But sometimes you’ll see that “eureka” moment when someone lights up from the new experience. Eating involves many kinds of sense perception, including smell, taste, texture, temperature, and sight.
Part one: Flavors & Scents
Fenugreek Leaf (Methi): fenugreek has an aroma reminiscent of maple syrup and is one of the magic ingredients in tandoori marinades. Crumbling dry herbs in your fingers will help release aromas.
Makrut (Kaffir) Lime Leaf: a crucial ingredient in many Thai curry pastes and soups. This double-lobed citrus leaf is available fresh at many asian groceries, and we’ve written about it before.
Curry Leaf: used in south Indian cuisine, such as the soups you find at dosa shops. We have a little curry tree, but leaves can be obtained fresh at Indian groceries.
Ajwain: spicy, somewhat reminiscent of thyme or oregano. Also from Indian cuisines and spice blends.
Saffron: always used in very small amounts due to its potency and expense. Almost never tasted alone.
Chat (Chaat) Masala: used primarily on Indian snack foods. Key spices include black salt, mango powder, cumin and asafoetida. Try it on some fresh fruit.
Black Salt: very sulfurous pink colored salt mined from the Himalayas.
Truffle Salt: an excellent way to experience the heady aroma of truffles. Try sprinkling it on vanilla ice cream.
Part two: Shapes
Sugar Crystals: these large (~1/4 inch) sugar crystals are available at Indian and middle-eastern markets, sometimes labeled as “sugar cubes” despite their elegant shapes. They don’t seem as sweet as granulated sugar because of the low surface area to volume ratio.
Salt Flakes (hopper crystals): because of the huge surface area, these taste even saltier than granulated salt. Great for when you want to have lots of salt flavor and are sprinkling on a surface that will not dissolve the salt. Trader Joe’s is selling small containers with huge crystals. Alternately, Maldon Sea Salt Flakes are large enough to see the crystal structure.
Shredded Red Pepper: we came across these dried pepper threads at a Korean grocery store and have been garnishing our soups with them ever since. They’re preserved with salt and rehydrate to show the cross section from the center of the fruit to the skin.They’re beautiful and spicy, but not as spicy as red pepper powder because of the difference in surface area.
Part three: Adventures
Citric Acid: we found large granules of this at an Indian market. One big granule is enough to make just about anyone pucker. This is the full-strength version of the powder that is used to make sour candies sour.
Sichuan Pepper (Prickly Ash, Wild Peppercorn): one of the components (hydroxy-alpha-sanshool) triggers an anesthetic reaction. After chewing on a couple of these husks, your tongue will go numb and tingly. It increases your ability to eat super spicy foods, and has been described to us as “a party in your mouth.” We’ve also seen very panicked faces of people who just wanted the sensation to stop. Some people don’t seem to be as sensitive to it, or perhaps didn’t get very active pieces, and they usually find the lemony flavor to be pleasant.
Super Soda Gum: we discovered this great bubble gum through the Candy Japan subscription service and we now purchase it at our local Japanese grocery store. It has a powerful punch of fizzy powder inside, which makes your mouth foam up like crazy. It is awesome good fun, and it seemed to help the sichuan pepper effect to subside. Even after the excitement from the foam settles down, it is really good quality gum.
Miracle Fruit Tablets: we got these tablets from Amazon. They’re a little bit expensive, but the miraculin binds to sweet receptors on the tongue, making sour foods seem sweet. The berries are also available, but are more expensive, and harder to get shipped.
Citric Acid (again): after dosing with the miracle fruit, citric acid tastes like candy. Be careful, or you’ll inadvertently eat a lot of highly acidic food because it is so fun. Try other sour foods like lemon, lime, grapefruit, vinegar, and tamarind.
Part four: Light
Wint-O-Green Lifesavers: sugar crystals are a triboluminescent material, meaning that when you crush them, they emit light. However, they emit ultraviolet light, and so we don’t normally get to see the effect. Wintergreen oil fluoresces blue, so eating wintergreen flavored candies in the dark in front of a mirror or with friends will let you see it. Go into a very dark room. Wait until your eyes are accustomed to the dark. Bite the mints with your teeth to crack them to see the glow.
Asafoetida (Hing): a very powerful garlic and onion substitute from Indian cuisine.
Seaweed: for someone who hasn’t been exposed to the flavor of dried seaweed, it can be a shock.
Dried Sumac: a sour fruit used in the spice blend za’atar along with sesame seeds and dried herbs.
Tamarind: a sour fruit that is less well known in mainstream American cuisine, but can be found in many familiar sauces (even some Worcestershire sauces). Commonly available as a paste or as pulp.
Other less common fruits, such as dragon fruit, soursop, jackfruit, and durian.
Fresh vs. freeze dried vs. canned textures and flavors.
From our group came the suggestion to create a flavor symphony, walking through various movements of flavor rather than isolating each one. It could be interesting to add more familiar herbs like mint, thyme, and rosemary to the mix.
An exploration like this is fairly simple to lead when everyone is in the same place, but can also be done remotely. We packaged up our ingredients into little bags and tucked them into plastic organizer boxes (commonly available from the dollar store) to conceal the contents until the right moment.
The list above is strongly influenced by our personal experiences and cooking preferences. Depending on your background, things we find exotic may seem perfectly normal. It is interesting to see which ingredients stir up memories from the participants, and which are new to them as well. If you come up with other ideas, we’d love to hear about them!
This little chunk of crystalline metal is a tiny slice of a meteorite — a rock that fell from the sky. When one says that, the next natural question is, “how do you know it’s a meteorite?” (We will get to that.) But what is really staggering is not just that we know, but how much we know about it and its history. And what a long history it is.
This specimen is a 68 gram sample cut from a fragment of the Muonionalusta meteorite. According to our best current understanding, the parent body that Muonionalusta came from was one of the earliest bodies to take shape during the formation of our solar system. It began as a protoplanet (or planetisimal) that accreted within the protoplanetary disk that would eventually become our solar system. It accreted over the course of roughly the first million years after the beginning or our solar system. (That is to say, during the first million years after the very first solids condensed from the protoplanetary disk.) The parent body had an iron-nickel “planetary” core, 50–110 km in radius, that was eventually exposed by collisions that stripped away most of its insulating mantle. It cooled very slowly over the next 1-2 million years. It is estimated (with startling precision) by Pb-Pb dating that the body crossed below a temperature of ~300 °C at 4565.3 ± 0.1 million years ago, just 2-3 million years after the solar system began to form. For the next four billion years, it led a largely unremarkable existence as an asteroid (minor planet) until it broke apart (possibly due to a major collision) about 400 million years ago. Then, one fine day roughly one million years ago, a large fragment entered the earth’s atmosphere, breaking into hundreds (perhaps, thousands) of smaller fragments that rained down in a shower of fire upon what is now northern Sweden and Finland. Four ice ages transported the surviving meteorite fragments across the Swedish tundra, until their first discovery (and naming after the nearby Muonio river) in 1906.