Okay, perhaps the title here is a bit of an exaggeration, but this black hole lamp made by [Will Donaldson] is an interesting approach to creating a black hole simulation without destroying the earth. This lamp uses a ring of LEDs surrounding a piece of black Lycra. A motor in the lamp base pulls the Lycra, representing the distorting effect that a singularity has on space-time. It also demonstrates how black holes can (in theory) evaporate by emitting radiation, a phenomenon called Hawking radiation. It’s a simple, but effective approach that physicists have used to demonstrate gravity for some time, using stretch fabric to simulate space-time and show how gravity warps it. It’s a two-dimensional version of a three (or more) dimensional phenomenon, but it works. And, hopefully, it won’t swallow the planet and destroy us all like the real thing might.
The Nintendo Switch portable gaming system is heavily locked down to prevent hacking, but the Labo add-on looks like it might be a different matter. The Labo is a series of add-on devices made of cardboard that does things like turn the Switch into a musical keyboard that plays a waveform on a card that you slot in. [Hunter Irving] decided to try a bit of reverse engineering on these cards to see if he could 3D print his own. Spoilers: he could.
[Hunter] started by taking one of the cards that come with the Labo and looking at the layout. These cards are, like the rest of the Labo, very simple: they are just shaped pieces of card that fit into the back of the keyboard add-on. When you press a button, the Switch camera reads the card to create the waveform. So, the process involved figuring out the required dimensions of the card to create a template. [Hunter] then created simple waveforms (square, sine, sawtooth) in Inkscape, and used this to create a 3D printable waveform card. A quick bit of 3D printing later, he had several cards ready, and these worked without problems. As well as the synthetic waveforms, he tried real ones, such as an organ, taking the waveform shape from the zoomed-in sample and using that to print. This post describes the process nicely and offers downloads of 9 sample cards and a template to create your own.
We suspect that this is only scratching the surface of what can be done with the Switch, Labo, and some ingenuity. Unlike the Switch itself, the Labo seems to be built for hacking, using simple, easy to use components to create surprisingly complex mechanisms that could be adapted for any number of purposes.
We’re sure this isn’t the only Labo hack we’ll be covering over the coming year. Not sure what all the fuss is about? Read our reporting on its arrival.
We’ve covered plenty of persistence of vision (POV) displays before, but this one from [Vadim] is rather fun: it’s built on top of a PC fan. He’s participating in a robot building competition soon and wanted to have a POV display. So, why not kill two birds with one stone and build the display onto a fan that could also be used for ventilation?
The display is a stand-alone module that includes a battery, Neopixels, Arduino and an NRF240L01 radio that receives the images to be displayed. That might seem like overkill, but putting the whole thing on a platform that rotates does get around the common issue of powering and sending signals to a rotating display: there is no need for slip connections.
[Vadim] goes into a good level of detail on how he built the display, including the problems he had diagnosing a faulty LED chip, and why it is important to test at each stage as it is easier to debug when the display isn’t whizzing around at high speed.
It’s a bit of a rough build that uses more protoboard than might be necessary, but we’re keeping our fingers crossed that it doesn’t fly off during the competition.
[Reiner Schmidt] was tired of renting an expensive 5-axis CNC head for projects, so he decided to build his own. It’s still a work in progress, but he’s made remarkable progress so far. The project is called Bridge Boy, and it is designed to use a cheap DC rotary mill to cut soft materials like plastic, wood and the like. Most of it is 3D printed, and he has released the Autodesk 360 plans that would allow you to start building your own. His initial version uses an Arduino with stepper drivers, and is designed to fit onto the end of a 60mm arm of a standard 3-axis CNC, so technically it’s a 3+2 axis CNC. With the appropriate software, it should be able to work as a full 5-axis machine, though, and it should be possible to integrate it with a CNC that has a 5-axis driver board without too much effort.
The old maxim is that if you pay peanuts, you get a monkey. That’s no longer true, though: devices like the Raspberry Pi W have shown that a $10 device can be remarkably powerful if it is well designed. You might not appreciate how clever this design is sometimes, but this great analysis of the antenna of the Pi W by [Carl Turner, Senior RF Engineer at Laird Technology] might help remind you.
[Claudio] covers everything from tearing down the broken iron to crafting a new tip that avoids problems with water droplets condensing on the brass tip that he used first. After salvaging the switch in the head that controls the steam, he carved a wooden handle that is soaked and coated with high-temperature resin. The hot end was then reinstalled, and the whole thing put together.
This build should be approached with some caution, though: anything that mixes high-pressure steam with electricity has the potential to go wrong in unpleasant ways, so be careful out there.
When a 13-year old Marie-Sophie Germain was stuck in the house because of the chaotic revolution on the streets of Paris in 1789, she found a refuge for her active mind: her father’s mathematics books. These inspired her to embark on pioneering a new branch of mathematics that focussed on modeling the real world: applied mathematics.
Post-revolutionary France was not an easy place for a woman to study mathematics, though. She taught herself higher maths from her father’s books, eventually persuading her parents to support her unusual career choice and getting her a tutor. After she had learned all she could, she looked at studying at the new École Polytechnique. Founded after the revolution as a military and engineering school to focus on practical science, this school did not admit women.
Anyone could ask for copies of the lecture notes, however, and students submitted their observations in writing. Germain got the notes and submitted her coursework under the pseudonym Monsieur Antoine-August Le Blanc. One of the lecturers that she impressed was Joseph Louis Lagrange, the mathematician famous for defining the mathematics of orbital motion that explained why the moon kept the same face to the earth. Lagrange arranged to meet this promising student and was surprised when Germain turned out to be a woman.
Gauss and Germain
‘Le Blanc’ also corresponded with German mathematician Carl Friedrich Gauss on number theory. When Napoleon’s armies occupied the town the famous mathematician lived in, Germain enlisted a family friend in the army to check that Gauss had not been harmed. Gauss didn’t realize who had helped him out, until he discovered that ‘Le Blanc’ was Sophie Germain, he wrote to her thanking her for her concern and praising her mathematical prowess given the hurdles set before her.
“How sweet is the acquisition of a friendship so flattering and precious to my heart. The lively interest you took during this terrible war deserves the most sincere recognition….But when a person of this sex, who, for our mores and prejudices, must recognize infinitely more obstacles and difficulties than men to become acquainted with these thorny searches, knows how to get rid of these obstacles and to penetrate what they have, most hidden, must undoubtedly, she has the most noble courage, talents quite extraordinary, genius superior.”
As well as working on the thorny and theoretical problems of number theory, Germain worked on applying mathematics to real world problems. One of these was a challenge set by the Paris Academy of Science to mathematically describe the elasticity of metal plates. An experimenter called Ernest Chladni had demonstrated that a metal plate would resonate in odd ways when vibrated at certain frequencies. If you put sand on the plate, it would collect in different patterns created by the resonance of the plate, called Chladni figures. To win the prize, the solution had to predict these figures.
The Mathematics of Stress and Strain
Mathematically predicting the behavior of metal plates could make it easier to design metal objects and predict how they would behave under stress. The prize was set in 1808 but was so difficult that Germain was the only one who decided to try to solve it, as it required coming up with a whole new way to analyze and describe how materials bend and change under stress.
The first two solutions that she submitted were rejected due to mathematical errors, but the third version won her the prize in 1816. However, due to the Academy policy of not allowing women to join (and to only attend events if they were wives of members), Germain was not able to attend the ceremony where the prize was granted. She was also not allowed to attend meetings of the Academy. After the Academy failed to publish her prize-winning work, Germain had to pay to publish the work herself in 1821.
Later, her friend Joseph Fourier allowed her to attend meetings and presentations, but the mathematical establishment never really accepted her, or her work. In a letter to a colleague in 1826 she complained about the way they rebuffed her:
“These facts are my domain and it is to me alone that they remain hidden. That’s the privilege of the ladies: they get compliments and no real benefits.”
In the same letter, Germain complained of suffering fatigue and she was diagnosed with breast cancer shortly afterwards. She died in 1831. Her final years were spent working on a solution to Fermat’s Last Theorem, and just before her death she published a partial solution that was the basis for much research into the theorem, which was finally solved only with computer help in the late 1990s.
Although Sophie Germain never earned a degree in her lifetime, she was given an honorary degree in 1837 from the University of Göttingen at the suggestion of Gauss, who noted that
“she proved to the world that even a woman can accomplish something worthwhile in the most rigorous and abstract of the sciences and for that reason would well have deserved an honorary degree.”
The Academy that snubbed her also now offers an annual prize for mathematics in her name. Perhaps more importantly, her work formed the basis of the study of elasticity and stress in metals that allowed engineers to build larger objects and buildings. Creations such as the Eiffel tower in 1887 were directly influenced by her work, and it laid some of the groundwork for Einstein’s theory of General Relativity.
Modern scholars argue that Germain could have been more than she was: her work, they argue, was hamstrung by a limited understanding of some of the fundamental concepts that Gauss and others had described. Although her work was fundamental and important, if she had been given free access to the education that she wanted and deserved, it’s easy to imagine that she would have gone farther.
The first two solutions that she submitted were rejected due to mathematical errors, but the third version won her the prize in 1816. However, due to the Academy policy of not allowing women to join (and to only attend events if they were wives of members), Germain was not able to attend the ceremony where the prize was granted. She was also not allowed to attend meetings of the Academy. After the Academy failed to publish her prize-winning work, 
