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15 Mesmerizing Science GIFs, Explained

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In 1987, Steve Wilhite gave the world an image format that would forever change the Internet: the GIF. Here are 15 science experiment GIFs—and what's going on in each.

1. BLUE MAGNETIC PUTTY

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You’ve probably played with thinking putty at least once in your life. If you haven’t, what you need to know is that it has viscoelastic properties, so you can pour it like a liquid but also bounce it like a solid. It’s also a dilatant fluid, meaning it will thicken increasingly with applied shear stress. Magnetic putty is the same substance, only this time, an iron oxide powder is added. The iron oxide will make the entire substance react to magnetic forces. Now all you need is a magnet, like the sphere above, and your putty will act like it has a mind of its own. Check out how you can make it yourself.

2. HUMAN LOOP

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We’ve seen people on skateboards and motorcycles loop the loop many times. Damian Walter is the first human to do it on foot. To run it without falling, you need to reach the right speed; then, centrifugal forces will keep you locked on the track. Note how his shoulder line stays dead center of the loop. For this particular one, Damian needed to accelerate up to 8.65 mph in the highest point to be able to gain enough inertia as to rotate his body and legs around his head fast enough, so when gravity finally wins, he’s already feet down on the track. The full video is part of a Pepsi promotional campaign.

3. QUANTUM LOCKING

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The edge of the table is a magnet and the puck is a regular wafer coated with a half micrometer (around one-hundredth the width of a hair) veneer of superconductor. Superconductors conduct electrical currents with zero resistance when cooled to extreme temperature (which is why the puck is frosted). The levitation is possible thanks to quantum locking (also known as flux pinning). Superconductors have zero electrical resistance, and they always want to expel magnetic fields from themselves. In this GIF, because the superconductor layer around the wafer is so thin, some magnetic field gets "trapped" inside it. The superconductor can’t move the magnetic field without breaking the superconducting state, so the trapped bits of magnetic field just stay there, locking the puck in a hovering position in midair. And because the track is a circle with the same magnetic field throughout, the puck can travel around without ever breaking the lock. If you want to see something really cool, the puck does the exact same thing even when flipped upside down

4. ORBITS OF EARTH AND VENUS

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Venus’ orbit around the Sun takes 224.7 Earth days. At first it just seems like a random number, but when scaled in time, we see that both planets interlock their orbits in a 13:8 ratio (Venus: Earth, respectively)—so for every eight years on Earth, Venus cycles around the Sun roughly 13 times. When we trace the two orbits for that time and draw a line between them each week, we see they draw a beautiful 5-fold symmetrical pattern. If we map each point when the two planets align with the Sun and run imaginary lines, we see a near-perfect 5-pointed star. Here's more about this phenomenon, and here's a very cool simulation.

5. SLINKY FALLING IN SLOW MOTION

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The slinky is simply a spring. When a spring is stretched, tension tries to pull it back together towards a collapsed state. The spring’s tension is occurring mostly symmetrically, so it pulls all ends towards the center. When dropped vertically, the bottom end is trying to fall down, but tension acts in the opposite direction, so the bottom of the spring remains stationary. Meanwhile, the top end is collapsing with G (9.81 m/s2) and spring tension. It's not until the rest of the spring hits the bottom of the spring, eliminating the tension that had counteracted gravity, that the slinky finally collapses and falls to the ground. Here is the Veritasium video this GIF is from, which explains it in more detail.

6. TOUCH-ME-NOT SEED POT EXPLODING

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Some plants have figured out astonishing ways to reproduce, including the jewelweed (Impatiens capensis), also known as the spotted touch-me-not. When the seeds mature enough to start a new generation, their pods develop a nastic response and explode, dispersing the seeds in the environment. When the time comes, the cells of the seed pod accumulate and store mechanical energy based on their hydration level. Any external stimuli then overloads the system, and the walls separate and quickly coil up on themselves, transferring energy to the seeds and launching them outwards. This study from the Journal of Experimental Biology explores how this mechanism works.

7. PINE CONE OPENING

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When it’s dry outside, pine cones open up to disperse seed. When it’s damp, it’s no longer a favorable condition, so they close to protect them. Pine cones are the most common example of a hygromorph, which changes shape based on humidity levels. The cells inside the cone are dead, and the triggered response is completely automatic. When they’re dry, a small section of the outer layer of the scale near the mid-rib shrinks, pulling the whole scale back and opening it up. When it’s damp, the moisture causes the layer to expand in such a way that it closes the cone. Here is a detailed study on the subject.

8. WATER TRANSFER PRINTING

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Water printing, a.k.a. hydrographics, is a fast and efficient method to coat an object. The hydrographic film is first placed on the surface of a tank with water. The film itself is soluble in water, so after a short time, it dissolves, leaving the ink calmly floating on the surface. The item is carefully dipped inside as to accurately transfer the texture and details of the film. A swirling motion disperses the ink to ensure the texture stays perfectly printed. The object then needs to dry and get a clear coat finish, just like any other printing process. Here's a Q&A about water printing.

9. ANTS ACTING AS A FLUID OR A SOLID

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Ants, being the social bunch they are, figure out that by grouping and acting like a single body, they can counteract external forces very effectively and, as a group, adapt to a variety of situations. By latching themselves to each other, they can create a single solid mass that’s elastic and springy in nature. This, for example, allows them to endure a big push, which would otherwise throw off a single ant. When they need to be more flexible with their surroundings, they simply move around within the body of ants and it allows them to act as a fluid and easily overcome obstacles. Take a look at this great production by the New York Times.

10. DIVERS UPSIDE DOWN UNDER THE ICE

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When you notice that the air bubbles “fall down,” you’ll realize these divers are actually walking upside down on the underside of the ice on a frozen lake. This becomes possible when they inflate their gear with air, which increases their buoyancy and makes them go up. A little fine tuning, and they can simulate gravity upside down. They can do that as long as they have air in their bottles, because the water pressure around them is supporting their entire bodies from all sides. Watch the original video.

11. WATERMELON EXPLODED BY RUBBER BANDS54 - Exploding A Watermelon With Rubber Bands.gif

The watermelon’s outer wall is usually pretty rigid and durable. Slowly wrapping rubber bands around it gently increases external pressure, which is squeezing the interior of the watermelon onto either side of the rubber band, increasing the pressure on those other areas. Notice also how they go along the short side, which is weaker than the longer one. At around 500 rubber bands, the external pressure eventually forces the watermelon to distribute so much internal pressure to the upper and lower shells that it cracks the outer wall (notice how the first crack appears at the very top, and that’s quickly followed by a crack a couple inches above the rubber bands. Those were weak points). And without watermelon inside, the wall is much easier for the rubber bands to break. After they’ve gone through the wall, the flesh of the fruit provides little resistance, so they snap and transfer all the force to the melon from the inside, which makes it explode outwards. Here is the original video from the Slo Mo Guys.

12. LUNAR PHASES ASSEMBLED

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One full revolution of the Moon around the Earth takes about 29.53 days. In this time it goes through several phases, all of which are characterized by the portion of the Moon that’s visible to the Earth. In the new moon phase, the Moon stands between our planet and the Sun. Since the Sun is the only major source of light in the Solar System, the moon is in shadow. (That faint brightness on the moon around this time is because of earthshine—sunlight reflecting off the Earth onto the moon.) At the opposite end of this cycle, the “Full Moon” phase, the Moon is on the opposite side of the Earth, illuminated by the Sun, and thus we see the entire side of the Moon that always faces us (thanks to tidal locking). Here's some good reading material on lunar phases.

13. GLASS FRACTURING AT 10 MILLION FPS

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Glass is a peculiar material. It’s incredibly durable to compression, to the point where to shatter a cube of one cubic centimeter, you’d require a load of 10 tons. Regardless, the average tensile strength of glass is very low, making it amazingly weak against fast and focused blows. Scientists have yet to discover exactly how glass shatters on an atomic level, but at least we can enjoy these beautiful fractals while we're waiting for them to figure it out. Here are some theories about how glass breaks.

14. NON-NEWTONIAN FLUIDS

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Unlike regular fluids, non-Newtonian fluids change their behavior based on your interaction with them. For example, when one type of non-Newtonian fluid is introduced to high stress, like a fast hit, its viscosity increases, and it thickens up to act like a solid. This is because the particles inside a non-Newtonian fluid are many times larger than in a regular fluid. When exposed to an action that would result in a very fast deformation, they simply don’t have the time to move around and reshape their form, so they resist. When approached gradually, the non-Newtonian fluid will act as expected. Quicksand is a natural example of this phenomenon. Here's an in-depth further read, and a very entertaining video.

15. GLADIATOR SPIDER HUNTING

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Most spiders spend their time weaving great networks of webs to trap any unfortunate visitor. Rather than take the passive approach, the gladiator spider has inverted the process and leads a rather active hunting life. It carefully weaves a quadratic net, which is very elastic, and although not very sticky, it does well to entangle whiskers, bristles, and hairs. When it’s ready, the gladiator spider waits for the perfect moment. Its eyes are very developed and allow it to spot prey in near darkness. After it’s close enough, the spider pounces downward while extending the net, trapping the insect. Watch the full video here.

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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8 Common Dog Behaviors, Decoded
May 25, 2017
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iStock

Dogs are a lot more complicated than we give them credit for. As a result, sometimes things get lost in translation. We’ve yet to invent a dog-to-English translator, but there are certain behaviors you can learn to read in order to better understand what your dog is trying to tell you. The more tuned-in you are to your dog’s emotions, the better you’ll be able to respond—whether that means giving her some space or welcoming a wet, slobbery kiss. 

1. What you’ll see: Your dog is standing with his legs and body relaxed and tail low. His ears are up, but not pointed forward. His mouth is slightly open, he’s panting lightly, and his tongue is loose. His eyes? Soft or maybe slightly squinty from getting his smile on.

What it means: “Hey there, friend!” Your pup is in a calm, relaxed state. He’s open to mingling, which means you can feel comfortable letting friends say hi.

2. What you’ll see: Your dog is standing with her body leaning forward. Her ears are erect and angled forward—or have at least perked up if they’re floppy—and her mouth is closed. Her tail might be sticking out horizontally or sticking straight up and wagging slightly.

What it means: “Hark! Who goes there?!” Something caught your pup’s attention and now she’s on high alert, trying to discern whether or not the person, animal, or situation is a threat. She’ll likely stay on guard until she feels safe or becomes distracted.

3. What you’ll see: Your dog is standing, leaning slightly forward. His body and legs are tense, and his hackles—those hairs along his back and neck—are raised. His tail is stiff and twitching, not swooping playfully. His mouth is open, teeth are exposed, and he may be snarling, snapping, or barking excessively.

What it means: “Don’t mess with me!” This dog is asserting his social dominance and letting others know that he might attack if they don’t defer accordingly. A dog in this stance could be either offensively aggressive or defensively aggressive. If you encounter a dog in this state, play it safe and back away slowly without making eye contact.

4. What you’ll see: As another dog approaches, your dog lies down on his back with his tail tucked in between his legs. His paws are tucked in too, his ears are flat, and he isn’t making direct eye contact with the other dog standing over him.

What it means: “I come in peace!” Your pooch is displaying signs of submission to a more dominant dog, conveying total surrender to avoid physical confrontation. Other, less obvious, signs of submission include ears that are flattened back against the head, an avoidance of eye contact, a tongue flick, and bared teeth. Yup—a dog might bare his teeth while still being submissive, but they’ll likely be clenched together, the lips opened horizontally rather than curled up to show the front canines. A submissive dog will also slink backward or inward rather than forward, which would indicate more aggressive behavior.

5. What you’ll see: Your dog is crouching with her back hunched, tail tucked, and the corner of her mouth pulled back with lips slightly curled. Her shoulders, or hackles, are raised and her ears are flattened. She’s avoiding eye contact.

What it means: “I’m scared, but will fight you if I have to.” This dog’s fight or flight instincts have been activated. It’s best to keep your distance from a dog in this emotional state because she could attack if she feels cornered.

6. What you’ll see: You’re staring at your dog, holding eye contact. Your dog looks away from you, tentatively looks back, then looks away again. After some time, he licks his chops and yawns.

What it means: “I don’t know what’s going on and it’s weirding me out.” Your dog doesn’t know what to make of the situation, but rather than nipping or barking, he’ll stick to behaviors he knows are OK, like yawning, licking his chops, or shaking as if he’s wet. You’ll want to intervene by removing whatever it is causing him discomfort—such as an overly grabby child—and giving him some space to relax.

7. What you’ll see: Your dog has her front paws bent and lowered onto the ground with her rear in the air. Her body is relaxed, loose, and wiggly, and her tail is up and wagging from side to side. She might also let out a high-pitched or impatient bark.

What it means: “What’s the hold up? Let’s play!” This classic stance, known to dog trainers and behaviorists as “the play bow,” is a sign she’s ready to let the good times roll. Get ready for a round of fetch or tug of war, or for a good long outing at the dog park.

8. What you’ll see: You’ve just gotten home from work and your dog rushes over. He can’t stop wiggling his backside, and he may even lower himself into a giant stretch, like he’s doing yoga.

What it means: “OhmygoshImsohappytoseeyou I love you so much you’re my best friend foreverandeverandever!!!!” This one’s easy: Your pup is overjoyed his BFF is back. That big stretch is something dogs don’t pull out for just anyone; they save that for the people they truly love. Show him you feel the same way with a good belly rub and a handful of his favorite treats.

The best way to say “I love you” in dog? A monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other good stuff (and in return, you’ll probably get lots of sloppy kisses). Visit BarkBox to learn more.

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