A digital, 3D printed sundial whose precise holes cast a shadow displaying the current time

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Julldozer created an amazingly clever digital sundial ("Cadran Solaire Numérique") that precomputes the angle of the sun throughout the day and uses those computations to make hundreds of precise holes calibrated to cast a shadow displaying the present time. Read the rest

Scientist model brain wrinkles with gel in a glass jar

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Have you ever tried to draw a brain? I find it hard to get the wrinkles to look right. Scientists at at the University of Jyväskylä in Finland made a solid model of a fetal brain out of gel that developed its own realistic furrows just by dunking it into a solvent.

From BBC:

They made a solid replica of a foetal brain, still smooth and unfolded, and coated it with a second layer which expanded when dunked into a solvent.

That expansion produced a network of furrows that was remarkably similar to the pattern seen in a real human brain.

This suggests that brain folds are caused by physics: the outer part grows faster than the rest, and crumples.

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The science of skipping stones

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The tl;dr: hit the water at a 20% angle. But the answer isn't as interesting as the question…

Bocquet’s quest to understand how this happens — how a solid object can skim along water without immediately sinking — began more than a decade ago, while he was skipping stones on the Tarn River in southern France with his young son. ‘‘He turns to me,’’ Bocquet says, ‘‘and asks, ‘Why does the stone bounce on the water?’ ’’ To answer that question satisfactorily, Bocquet and his colleagues built a mechanical stone skipper and analyzed the angle of each toss using high-speed video. They also created a set of mathematical equations to predict the number of skips.

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Boneless simulated human tumbling through endless giant LEDs

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Can't get enough of nude, 3D-modelled humans with the internal physics of bags of jelly interacting with physics simulations? We've got you covered with Albert Omoss's Plug Party 2K3. (via JWZ) Read the rest

Elegance, illustrated: heliocentrism vs geocentrism

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In a gorgeous animation, Malin Christersson shows how much simpler it is to plot out celestial mechanics when you assume that all the bodies in our solar system are in orbit around the sun, rather than the other way around. Read the rest

Gravity visualized with a big sheet of stretched Lycra

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AP physics teacher Dan Burns gave a fun demonstration about spacetime curvature in 2012 at Los Gatos High School. Here's the 10 minute video.

Here's another good one from Burns: the "Pole and Barn Paradox":

This is my favorite Special Relativity paradox. It will blow your student's minds. A runner traveling at 0.87c with a 20 m long pole runs through a 10 m long barn. To the barn FOR the pole shrinks and the barn doors can be closed for an instant with the ole completely inside. From the runner's frame of reference the barn contracts to 5 m and the pole can NOT fit with both doors closed! How is this resolved? You can use the slides and associated videos to go though this mind-bender with an added twist at the end.

[via]

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Make: the simplest electric car toy, a homopolar motor

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Put round magnets on either end of a AA battery and set it down on a sheet of tinfoil and watch it spin! It's a homopolar motor, a simple electric motor that relies on the Lorentz effect to set it in motion.

Kottke explains: Read the rest

Stephen Hawking cancels appearances because of “ill health”

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Cambridge University today said that Stephen Hawking is cancelling several public appearances because of ill health.

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Entropy explained, beautifully, in comic-book form

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Nick Sousanis became a Boing Boing favorite for his 2015 doctoral dissertation in graphic novel form, and since attaining his PhD, he's become a postdoctoral fellow in Comics Studies at the University of Calgary. Read the rest

Sagan, Hawking, and Clarke have a gabfest (1988)

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Watch these three guys discuss "God, The Universe and Everything Else," which includes extraterrestrials, creativity, science fiction, education, the Cold War, fractals, and so much more.

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Actual textbook physics problem

You are kidnapped by political-science majors (who are upset because you told them political science is not a real science). Although blindfolded, you can tell the speed of their car (by the whine of the engine), the time of travel (by mentally counting off seconds), and the direction of travel (by turns along the rectangular street system). From these clues, you know that you are taken along the following course: 50 km/h for 2.0 min, turn 90° to the right, 20 km/h for 4.0 min, turn 90° to the right, 20 km/h for 60 s, turn 90° to the left, 50 km/h for 60 s, turn 90° to the right, 20 km/h for 2.0 min, turn 90° to the left, 50 km/h for 30 s. At that point, (a) how far are you from your starting point, and (b) in what direction relative to your initial direction of travel are you? – From Halliday & Resnick Fundamentals of Physics Extended 9th Edition Read the rest

Heathrow security insists that ice is a liquid

Simon Perry froze a can of Diet Coke solid and took it through security at London's Heathrow Airport to see whether he could find a loophole in the "no liquids" rule. Read the rest

World's most powerful digital camera gets green light from U.S. Dept. of Energy

”The LSST’s camera will include a filter-changing mechanism and shutter. This animation shows that mechanism, which allows the camera to view different wavelengths; the camera is capable of viewing light from near-ultraviolet to near-infrared (0.3-1 μm) wavelengths.
Illustration: SLAC National Accelerator Laboratory.”
Construction has been okayed for a 3.2-gigapixel digital camera, which would be the world’s largest, at the heart of the Large Synoptic Survey Telescope.

Watch: Tiny floating robot can jump from water's surface

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Researchers led by Je-Sung Koh created a biomimetic robot that floats using surface tension and can jump from the surface of water like a water strider insect. Read the rest

Why magenta doesn't appear in the rainbow

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Steve Mould's colored flashlights (sometimes called "coloured torches" in distant lands) are useful props in this excellent 5-minute lecture on color mixing. I learned that magenta is not a color. Rather, it is the absence of green.

[via] Read the rest

Gorgeous mirrored room with 250 colorful fluorescent tubes

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The UK's National Media Museum currently hosts a Festival of Light installation by Liz West. An Additive Mix fills the room with white light, teaching visitors about the concept of additive color.

Liz will be at the museum in person for free family talks on July 23.

Light Fantastic: Adventures in the Science of Light (via) Read the rest

Ant-Man, the Physics of Shrinking, and the Higgs Boson

It's simply a cross-interaction between the Higgs field and the Pym field!

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