Scientists generate electricity from shadows

In most approaches to convert light into electricity, shadows are a bummer. Now though, researchers from the National University of Singapore (NUS) devised a shadow-effect energy generator (SEG) that scavenges electricity from the contrast between light and shadow.

“When the whole SEG cell is under illumination or in shadow, the amount of electricity generated is very low or none at all. When a part of the SEG cell is illuminated, a significant electrical output is detected. We also found that the optimum surface area for electricity generation is when half of the SEG cell is illuminated and the other half in shadow, as this gives enough area for charge generation and collection respectively,” says MUS physicist Andrew Wee in an NUS News article.

From the researchers' technical paper in the journal Energy & Environmental Science:

Our SEG performs 200% better than that of commercial silicon solar cells under the effects of shadows. The harvested energy from our generator in the presence of shadows arising at a very low intensity (0.0025 sun) can drive an electronic watch (1.2 V). In addition, the SEG can serve as a self-powered sensor for monitoring moving objects by tracking the movement of shadows. With its cost-efficiency, simplicity and stability, our SEG offers a promising architecture to generate green energy from ambient conditions to power electronics, and as a part of a smart sensor systems, especially in buildings.

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See-thru rockets are GO for launch!

If you're as ancient as I am, you might remember that awesome line of Revell "Visible" model kits: The Visible Man, Visible Woman, Visible V-8, Visible Mustang, etc. These see-thru models were a fun way to teach kids what lies beneath the surfaces of biological and mechanical worlds. I loved these kits!

Now, thanks to the wonders of modern desktop animation, we have this video of four transparent rockets showing engine burn and staging, from launch to orbital insertion.

Key: Red = Kerosene RP-1 Orange = Liquid Hydrogen LH2 Blue = Liquid Oxygen LOX

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How to improve your fried rice using physics

Apparently a high percentage of chefs at Chinese restaurants suffer shoulder plane from wok tossing. They must rapidly move the heavy pan to launch the food into the air so it cooks but doesn't burn, even though the temperatures may hit 1200°C. Recently, Georgia Tech mechanical engineers studied the kinematics of Chinese restaurant chefs to understand how they actually move and the "optimal regime for making fried rice." According to their scientific paper, they hope their study can not only lead to better fried rice for all but also "inspire the design of stir-fry robotics and exoskeletons to reduce the rate of muscle strain injury among professional chefs." From their scientific paper:

Tossing is a combination of two independent motions, a side to side motion and a see-saw motion, allowing rice grains to slide around the wok as well as to jump off the surface. We identify two critical parameters that chefs can vary: the frequency of tossing and the phase lag between the two motions applied. By filming professional chefs, we found that, at the frequency chosen by chefs, the phase difference performed is optimal for mixing. We suggest that future chefs increase the frequency of motion, which may enable rice to jump further, and promote cooling and mixing.

"The physics of tossing fried rice" (Journal of the Royal Society Interface via Science News) Read the rest

Incredible no-glue toilet paper roll model of buckminsterfullerene

Once you run out of toilet paper–and you will–make sure you keep the empty rolls so you can try making fantastic molecular models! Physicist and 3D software engineer Ricky Reusser flattened and linked the cardboard tubes into models of buckminsterfullerene and carbon nanotubes! He's even written a software simulator so you can keep making these even once you've used your toilet paper rolls in place of the toilet paper you can't get. From his guide, Toiletpaperfullerenes and Charmin Nanotubes:

Toilet paper tubes have the curious property that you can flatten them, cut out loops, and link the loops together without fasteners[...]

My brand is regular Trader Joe's toilet paper, though I have no reason to believe anything about the brand is particularly important, beyond consistency—with the exception of those cowards who make tube-free toilet paper rolls. Those won't work. I've considered side-stepping material collection and waiting to buy tag board when shelter-in-place eases, though to be honest, the recycled nature of the raw materials is no small part of what draws me to this project.

(via Kottke) Read the rest

Why is an empty shampoo bottle so easy to knock over?

Jerome Licini is a professor at Lehigh University. He and one of his students developed an apparatus to demonstrate why empty shampoo bottles tip over so easily. The reason: empty bottles have much less mass than full bottles, and their center of gravity is higher so they are basically begging to fall over at the slightest touch. Read the rest

What happens when you shoot a Nerf bullet backward while driving the bullet's speed

If you are a fan of the book Thinking Physics, you might like this episode of The Action Lab, in which the Action Man tests "the laws of physics to show what happens if you fire a bullet backwards and you are traveling at the same speed forward. Will the bullet just fall to the ground?" Read the rest

Undersea telescope seeks out dark matter

More than 125 of these curious soccer ball-sized glass spheres hang near the floor of the Mediterranean Sea. Even though they're deep underwater, they're keeping a constant vigil for neutrinos, particles that may be evidence of dark matter, supernovae, and neutron stars far off in intergalactic space. Eventually, the Cubic Kilometer Neutrino Telescope (KM3NeT) will consist of 6,000 spheres suspended across one cubic kilometer of seawater. Often, neutrino detectors are located deep underground because the Earth itself helps isolate the instrument from background radiation and cosmic rays so the neutrinos are more easily spotted. From Scientific American:

“Perhaps one or two neutrinos in a million will interact with quarks inside the nucleus of either hydrogen or oxygen” in the water, says the project's physics and software manager, Paschal Coyle of the Marseille Particle Physics Center. “Because the cosmic neutrinos possess very high energy, the result of such interactions is the release of a charged particle that travels very fast.”

In fact, it travels through the water faster than light can, producing an effect Coyle likens to an optical equivalent of the Concorde jet's sonic boom. Researchers can determine the original neutrinos' energy and direction using the faint light released—so-called Cherenkov radiation—picked up by the undersea sensors.

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Freeman Dyson as remembered by Tim O'Reilly

Legendary physicist and mathematician Freeman Dyson, whose mind-blowing work ranged from quantum electrodynamics to nuclear engineering to the search for extraterrestrial intelligence, died last week at 96-years-old. Tim O'Reilly just published a tribute to Dyson's genius, curiosity, kindness and unique lens on, well, everything. From O'Reilly Radar:

When I interviewed Freeman on stage at OSCON in 2004, along with his son George, the subject strayed to digital preservation. I lamented how much would be lost due to incompatible standards for information storage, and he said, “Oh no, forgetting is so important! It is what gives room for new ideas to come in.” This was such a typical Freeman moment: bringing a profoundly fresh perspective to any discussion. Perhaps the most famous example is the paper he wrote in 1949 at the age of 25 making the case that the visualizations of Richard Feynman were mathematically equivalent to the calculations of the more conventional physicists Julian Schwinger and Shin’ichirō Tomonaga, a paper that led to Feynman, Schwinger, and Tomonaga receiving the 1965 Nobel Prize in Physics for the theory of quantum electrodynamics...

After George sent an email to a group of friends about Freeman’s death, Danny Hillis replied with a story that seems to perfectly encapsulate this gift of Freeman’s for seeing things that others missed. “I visited him recently,” Danny wrote, “and we got into a conversation about self-organizing systems. After lunch we climbed up the long stairs to his office, and when we sat down he seemed a bit distracted.

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Chaotic pendulum wanders field of magnets

Markhacks creates cardboard pendulums and such. Here's one with a bunch of bothersome magnets underneath the weight.

I made another pendulum of cardboard. Using multiple magnets with reversed polarity causes chaotic motion.

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See the magic of a Tesla Valve

In 1920, the great Nikola Tesla patented this ingenious valve that allows fluid or gas to flow in one direction but not the other. And it does it based entirely on its geometry without any moving parts. Here is the US patent, number 1,329,559.

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A freight train's emergency brake is applied at 40 MPH. How long does it take to stop?

This video captures a freight train engaging its emergency brake (about 2m in) and grinding slowly to a stop. Momentum is everything... until it's nothing. Read the rest

"Softbody Tetris": what if tetronimoes were made of jello?

C4D4U's SOFTBODY TETRIS V16 is (as the name implies), the latest in a series of "softbody" simulations of Tetris, in which the tetronimoes are rubbery, jelly-like solids that glisten as they wobble into place. It's an incredibly soothing thing to watch (C4D4U calls them "ASMR for my eyes") and part of a wider genre of softbody sims. JWZ argues that this "becomes intolerable" upon the "realization that completed rows don't liquify" but if that's your thing, you need SOFTBODY TETRIS V9. Read the rest

Light is slow, actually

This video depicts light speed in contexts where it appears to be slow. The moon is 1.2 light seconds from Earth; Mars several light minutes. This is, of course, why humans aren't moving out of this solar system any time soon. Read the rest

Talking science fiction, technological self-determination, inequality and competition with physicist Sean Carroll

Sean Carroll is a physicist at JPL and the author of many popular, smart books about physics for a lay audience; his weekly Mindscape podcast is a treasure-trove of incredibly smart, fascinating discussions with people from a wide variety of backgrounds. Read the rest

What the hell is a "dimension" anyway?

Caltech theoretical physicist Sean Carroll, author of Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime, explains the concept of a "dimensions" at five different levels of complexity. Dr. Carroll sure has a big brane. Read the rest

Toto's no good very bad encounter with gravity

Don't think his manager won't raise hell over their client working under these unsafe conditions. Read the rest

Engineers developed a mathematical model of Ooblek

A favorite kitchen chemistry (and physics) experiment of kids (and adults), Ooblek is the weird result of mixing cornstarch with water. Now, MIT engineers have developed a mathematical model that can predict and simulate how the non-Newtonian fluid switches between liquid and solid depending on the pressure applied to it. From MIT News:

Aside from predicting what the stuff might do in the hands of toddlers, the new model can be useful in predicting how oobleck and other solutions of ultrafine particles might behave for military and industrial applications. Could an oobleck-like substance fill highway potholes and temporarily harden as a car drives over it? Or perhaps the slurry could pad the lining of bulletproof vests, morphing briefly into an added shield against sudden impacts. With the team’s new oobleck model, designers and engineers can start to explore such possibilities.

“It’s a simple material to make — you go to the grocery store, buy cornstarch, then turn on your faucet,” says Ken Kamrin, associate professor of mechanical engineering at MIT. “But it turns out the rules that govern how this material flows are very nuanced...”

Kamrin’s primary work focuses on characterizing the flow of granular material such as sand. Over the years, he’s developed a mathematical model that accurately predicts the flow of dry grains under a number of different conditions and environments. When (grad student Aaron) Baumgarten joined the group, the researchers started work on a model to describe how saturated wet sand moves. It was around this time that Kamrin and Baumgarten saw a scientific talk on oobleck.

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