Latest StoriesPhysics
    How Scientists Visualize Sound with a Photography Trick

    You can actually see sound waves as they travel through the air thanks to a clever photographic trick. NPR's Adam Cole, who runs the the Skunkbear science Tumblr, produced this video explaining how scientists use a technique called Schlieren Flow Visualization--the combining of two mirrors, a barrier, and a high-speed camera--to visualize the effect of sound waves through space. It's the same technique used to visualize other "invisible" processes, like the turbulence around an airplane wing or rising heat from a hot surface.

    Tested Explains: What The Heck is Inflation Theory?

    If you were conscious on Monday you probably heard there was big news out of the physics community. So big, in fact, that there’s already talk of Nobel prizes and jokes about Einstein patting himself on the back for being proven right...again. Let’s be honest though, big physics news is always kind of hard to understand. There’s always GeV’s and B-modes and jargon and, well, math. So, in the event that you’d actually like to understand what the heck everybody is talking about right now I called up my favorite theoretical physicist, CalTech’s Sean Carroll, to help explain the theory of inflation for those of us that don’t do physics. Here it is, in the simplest possible terms.

    Image credit: California Academy of Sciences

    The universe is the same everywhere we look. No matter where we point our telescopes out into the 14 billion light years of space in all directions, we see the same density of stuff. Same amount of matter and number of galaxies. Same gravitational field. The universe is even basically the same temperature everywhere.

    The theory is that in the very first fraction of a second after the big bang happened, the universe expanded into existence.

    It’s awfully smooth, flat, and uniform -- and there’s gotta be a reason why. Inflation theory explains. Simply put, the theory is that in the very first fraction of a second after the big bang happened, the universe expanded into existence. In other words, everything, everywhere existed all at once and it happened faster than the speed of light.

    That’s it. Pretty simple, right? Well, it sounds simple. Until you try to prove that it’s true. Since we can’t go back in time to watch the creation of the universe (whomp whomp), the best way to know that theory is right is to look for leftovers of its aftermath. So scientists have been trying to spot evidence that the rapid inflation of the universe messed with gravity.

    At NASA, Bugs Get Splattered for Science

    Here’s the thing about airplanes: In order to function at peak efficiency their wings have to be completely smooth. In engineering they call it optimal laminar flow--meaning air can move over the wings without any disruption. But there’s a big problem in achieving optimal flow when you take airplane wings out of an engineer’s wind tunnel and put them into use outdoors. Actually, it’s not a big problem. It’s a bug problem.

    It’s kind of hard to believe, but even the smallest of bumps on a wing can mess up laminar flow. All those accumulated bug guts eventually mess up an airplane’s fuel efficiency by increasing drag. It’s a problem that folks have been attempting to solve for more than 60 years. The good news is NASA is on it. Their Langley-based bug team is working on finding the optimal material for repelling bug innards.

    Photo credit: Flickr user tabor-roeder via Creative Commons

    But why is this problem taking so long to solve? According to Mia Siochi, who heads up the team, when she was first tackling a similar problem more than 25 years ago their focus was on surface tension. They’d look at materials like those you use to create anti-stain surfaces on carpet or Teflon. “These materials let water bead on the surface. For things to stick they have to spread,” she says.

    When a bug goes splat, its body goes through chemistry that thickens its fluids.

    But the problem is that bug guts aren’t nearly as simple as water. Turns out, there’s some interesting chemistry that happens inside a bug when it’s about to die. “When the aircraft hits the bugs it’s going at around 150 miles an hour. That’s high impact dynamics. The components of the bug and the blood, it’s a lot of water, but there are a lot of biological components there too. The bug doesn’t know it’s been catastrophically destroyed. So it’s trying to heal. It goes through chemistry that thickens its liquids,” she says.

    To counteract this problem, the team is now looking at more modern ideas. Specifically, superhydrophobic chemistry and biologically-inspired surfaces. By combining chemicals that repel water with surfaces that are textured on a microscopic level (like a lotus leaf) they have begun to have success.

    To test how their new surfaces work, the team has reverse-engineered a vacuum pump to shoot instead of suck. It was a bit of a challenge because the bug has be alive until it hits the surface. If it gets smashed on the side of the gun on its way out the chemistry will be different once it hits its final destination. Once it smushes, they measure the characteristics of the bug residue--how big is the area that it spreads and how high it is?

    Photo credit: NASA

    According to Siochi: “This is uncharted territory in some ways. When we started we actually used bigger bugs. We thought: what’s alive and easy to get? It’s crickets. We started using a fan and a big opening and we’d drop the crickets in. But when you shoot too many you have bug splat on top of bug splat. And then we went to feeding a single bug in at a time.

    We’re materials people. The aerodynamics expert told us our bug was too big. You wouldn’t be hitting a cricket with a plane. So we decided we had to go smaller, but how small? When I was doing the test 25 years ago we mounted samples to a car and drove around. This was at Virginia Tech and a professor of entomology there could look at the splats and tell which bugs were which. So for this project we went back to that table and tried to figure out what was the largest population of bugs that hit the car. So we got flightless fruit flies. And then we had to learn how to propagate them.”

    Urinal Dynamics: How To Avoid Splash

    BYU's Splash Lab (yep, a real department at the University) recently conducted a series of experiments in urinal dynamics--the study of the physics of bathroom usage. Using high-speed video and simulations of male urination in both toilets and urinals, the researchers prescribe the best angle of attack to reduce hazardous splash. Their recommendation: aim for a vertical surface and at a decreased angle to reduce bounceback, and stand close enough to the urinal to prevent the stream from becoming individual droplets before they hit the surface. Maybe it's time to move those urinal fly decals.

    The Story of the First Recorded Human Voice

    Physicist Carl Haber is one of 2013's MacArthur Fellows, the recipient of a genius grant from the MacArthur Foundation. Haber deserves the genius label. Over the past five years, his work on a system called IRENE at the Lawrence Berkeley National Laboratory has helped play back audio recorded more than 100 years ago, even when the recording medium was obsolete or in terrible condition. If that concept sounds vaguely familiar, it should--earlier this year Haber was the first person to hear Alexander Graham Bell's voice preserved in an 1885 recording.

    As described by the MacArthur Foundation, IRENE (which stands for Image, Reconstruct, Erase, Noise, Etc.) is "a non-contact method for extracting high-quality sound from degrading or even broken analog recordings on two- or three-dimensional media. A disc or cylinder is placed in a precision optical metrology system, where a camera following the path of the grooves on the object takes thousands of images that are then cleaned to compensate for physical damage; the resulting data are mathematically interpolated to determine how a stylus would course through the undulations, and the stylus motion is converted into a standard digital sound file."

    If you try to play a vinyl record on your average turntable, a lot of things can wreck your sound. Scratches create annoying skips. Dust collecting on the needle can muddle playback. And if a record is broken, it's unplayable. But that's not the case with IRENE, which can create a digital image of a record even if it's broken into pieces. IRENE is smart enough to skip over scratches and cracks and, essentially, create a musical photocopy.

    The voice of Alexander Graham Bell holds a special place in the history of technology, since his invention of the telephone revolutionized communication. Bell's recordings weren't the first that Haber helped restore, though. Back in 2008, he helped play back the earliest known recording of a human voice, which was made in 1860--17 years before the invention of the phonograph, and 25 years before Bell's recording. In this case, "recording" doesn't mean exactly what we would think.

    French printer Édouard-Léon Scott de Martinville invented phonautograms in the 1850s and was interested in recording human speech--playing that speech back like a record, however, was not part of the plan. Wikipedia explains that Scott's phonautograph "transcribed sound waves as undulations or other deviations in a line traced on smoke-blackened paper or glass. Intended solely as a laboratory instrument for the study of acoustics, it could be used to visually study and measure the amplitude envelopes and waveforms of speech and other sounds, or to determine the frequency of a given musical pitch by comparison with a simultaneously recorded reference frequency."

    Scott's sound recordings are archived on the website FirstSounds.org, which chronicles the effort that went into playing them back. For a century and a half, playing them seemed impossible. Then, in 2008, came IRENE. Haber's technology was able to read the lines scratched in soot as though they were the grooves of a record, creating a digital file.

    Playing them back, however, was still a huge challenge.

    Finally, We Know Why and How Tea Kettles Whistle

    The odds are good that you have a tea kettle sitting in your kitchen. Maybe you don't use it to make tea--maybe you heat water in it to make oatmeal or coffee. But just about everyone has a kettle, or is at least familiar with the whistle kettles make when their water heats up. Strangely, even after hundreds of years, no one knew exactly why kettles began to whistle when they reached a certain temperature. Or, more accurately, we didn't know how.

    The why is a simple answer: as steam builds up and heats up within the kettle, it causes vibrations. As the steam escapes the kettle more quickly, the vibrations grow more intense, and the whistling gets louder. But how does that produce the all-too-familiar whistling noise? "Although the sound of a kettle is understood to be caused by vibrations made by the build-up of steam trying to escape, scientists have been trying for decades to understand what it is about this process that makes sound," writes Phys.org.

    As far back as the 19th century, John William Strutt, 3rd Baron Rayleigh and author of the foundational text, The Theory Of Sound, was trying to explain it. In the end...Lord Rayleigh was forced to concede that 'much remains obscure as regards the manner in which the vibrations are excited.'

    Photo credit: Flickr user abject via Creative Commons

    Modern science, however, has cracked the case. A pair of researchers from Cambridge have tackled the problem and come up with an explanation. They modeled (in software) how air flows inside a kettle to explain why it creates a whistling noise. Once the air inside the kettle reaches a certain flow speed, small swirling vortices are created. And it's those vortices that can produce sound.

    "As steam comes up the kettle's spout, it meets a hole at the start of the whistle, which is much narrower than the spout itself," writes Phys.org. "This contracts the flow of steam as it enters the whistle and creates a jet of steam passing through it. The steam jet is naturally unstable, like the jet of water from a garden hose that starts to break into droplets after it has travelled a certain distance. As a result, by the time it reaches the end of the whistle, the jet of steam is no longer a pure column, but slightly disturbed. These instabilities cannot escape perfectly from the whistle and as they hit the second whistle wall, they form a small pressure pulse. This pulse causes the steam to form vortices as it exits the whistle. These vortices produce sound waves, creating the comforting noise that heralds a forthcoming cup of tea."

    The size and shape of the opening spout makes the kettle whistle rather than produce another sound. A shorter kettle spout produces a higher pitched whistle, and a longer spout produces a lower one.

    But here's the coolest part: That classic kettle whistle isn't the only sound kettles make. Just as water begins to boil, the kettle produces another sound, which is always at the same pitch as the whistle. That sound is produced by the same effect that causes sound when you blow across the top of an empty bottle. Air in the neck of the bottle is bouncing up and down, while the rest of the air in the bottle is compressed and then bounced upwards. The whistle of the kettle does the same thing.

    Now that these researchers have cracked the mystery of the kettle, they could likely design one that would produce no whistling noise when its water begins to boil. But who would want a silent kettle?

    Testing the Puffing Gun and Unexpected Food Explosions

    Puffing guns were invented over 100 years ago as a way to explosively puff foods like cereal. It's why we have Corn Pops. At a kitchen laboratory in New York, Dave Arnold and his team of molecular gastronomists are reviving the puffing gun, experimenting with ones used by street food vendors in Asia. The results are a tad unpredictable.

    Weird Microgravity Tests: Dropping Fish 360 Feet

    If there's one place fish feel especially out of place, it's probably falling through the air several hundred feet above ground or water. Unfortunately for some fish in Germany, that's exactly where they found themselves--falling about 360 feet through a towering hollow tube used as a testing ground for dropping things. Scientists can go to Bremen, Germany to study the effects of gravity and weightlessness as they fall inside an enclosed space. The fish were there to serve a special purpose: They were standing in for astronauts.

    Gizmodo writes that a pair of zoologists named R.H. Anken and R. Hilbig used fish as models to test the effects of microgravity. Studying how microgravity affects humans is more difficult and more expensive. So why not just throw a fish down 36 stories?

    Photo credit: Bremen Tourism

    "Anken and Hilbig point out, previous experiments performed elsewhere had already shown that fish 'reveal motion sickness"'when they 'transition from 1g to microgravity,' writes Gizmodo. "They thus did the next most obvious thing—what any of us would have done—they rigged a 'camcorder-equipped centrifuge' and they started dropping fish."

    After their initial study with small fish, the zoologists went back a second time with catfish in hand. Catfish normally swim upside down, so how would they react to swimming in microgravity? While it may be funnier to imagine the fish flopping about in the air during their fall, they were actually in small capsules containing water. And the catfish study produced very different results.

    Physicists Form New Matter By Coaxing Photons Into Molecules

    Science has done it. The seemingly impossible. Discovering the secret to what was, until now, certainly fictional. The lightsaber.

    "Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules – a state of matter that, until recently, had been purely theoretical," writes Phys.org. "Photons have long been described as massless particles which don't interact with each other. 'Photonic molecules,' however, behave less like traditional lasers and more like something you might find in science fiction – the light saber."

    Photo via Ro-Lightsaber.Blogspot.com

    Okay, so they haven't actually invented a lightsaber. Unfortunately. The photonic molecules aren't naturally taking the form of a sword that can cut through anything in existence. But the principle is similar, say the physicists. Normally photon have no mass and don't interact with one another. The experiment created a medium that caused photons to bind into molecules. Lukin said "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."

    Speaking practically, though, this discovery is more likely to benefit quantum computing than sci-fi sword fights. Photons are the best form to carry quantum information, but until now, they haven't been able to interact. There's now a proof-of-concept for how photons could help push quantum computing forward.

    Explaining how the photons form molecules is a little complicated. The key is an effect called the Rydberg blockade, which came into effect when the physicists put rubidium atoms in a vacuum chamber and chilled them to near-absolute zero. When they fired individual photos into the atom cloud using lasers, the photons excited atoms along their path, passing energy off as they went. And then, the Rydberg blockade. PHys.org explains:

    "When an atom is excited, nearby atoms cannot be excited to the same degree. In practice, the effect means that as two photons enter the atomic cloud, the first excites an atom, but must move forward before the second photon can excite nearby atoms.

    The result...is that the two photons push and pull each other through the cloud as their energy is handed off from one atom to the next."

    Now: How do we get that in the form of a sword?

    Shake Weighted: Simulating a 6.7 Earthquake

    This summer, 140 earthquakes jiggled, jolted and bounced two buildings in western New York. This wasn’t bad luck or some freak occurrence; the buildings were having a challenging July and August by design. See, the series of seismic events were produced not by tectonic plates, but by a pair of massive shake tables bridged over to create the largest earthquake simulation platform in the country. The University of Buffalo lab performs these powerful events for an audience of scientists and industry folks—all in order to test the mettle (and in this case metal) of a wide variety materials and systems.

    The most recent, massive show: Cold-formed steel, presented in two acts. The first cold-formed structure ready to rumble was a 50 foot long, 20 foot wide, and 20 foot tall two-story naked frame; the second was identical in size and shape, but dressed with all sorts of non-structure-sustaining elements, like drywall, a staircase—and eleven 2000-pound concrete blocks to simulate the weight of everything else typically inside an occupied building (furniture, air conditioning units, water heaters).

    Three years in the making, the tests drew researchers from six universities, steel industry design consultants, and nearly $1 million from the National Science Foundation. The goal was to gain a better understanding of how cold-formed steel stands up to extreme conditions. Better understanding leads to more informed computer models and building codes, so engineers and construction companies can hit that sweet spot of efficiency and safety.

    The Art of Making Holograms

    Gizmodo produced this wonderful video profile of Jason Sapan (AKA Dr. Laser), the proprietor of Holographic Studios in New York City. The laboratory/gallery is the only one of its kind in the city, founded by Sapan in the late 70s in what was formerly a blacksmith's subterranean forge. The gallery is open to the public and Sapan offers technical classes and workshops to pass on this unique skill of holography. It's one of the places that I definitely want to visit while we're in New York at the end of this week for World Maker Faire.

    How The Sabre Jet Engine Could Send a Ship to Space 100 Times a Year

    All that stands between the world and an engine that can propel a craft into low Earth orbit, with no expendable booster rockets, is $3.6 billion dollars. That's the amount of money aerospace company Reaction Engines needs to raise to finish funding Sabre, or the Synergistic Air-Breathing Rocket Engine. This engine, writes PopSci, is the key to the Skylon, a single-stage spacecraft Reaction Engines hopes to build. Unlike NASA's retired Shuttle, the Skylon would take off and land horizontally, and could conceivably make return trips to space within two days of landing.

    "Sabre has the unique ability to use oxygen in the air rather than from external liquid-oxygen tanks like those on the space shuttle," writes PopSci. "Strapped to a spacecraft, engines of this breed would eliminate the need for expendable boosters, which make launching people and things into space slow and expensive."

    Reaction Engines predicts the Skylon could make trips to space for as little as $10 million, far cheaper than the $100 million it cost to launch the space shuttle--with a two-month turnaround. A SpaceX launch costs around $54 million.

    Reaction Engines' breakthrough is its ability to convert extremely hot air into air cool enough for the engine to use. PopSci elaborates: "In November, Reaction Engines hit a critical milestone when it successfully tested the prototype’s ability to inhale blistering-hot air and then flash-chill it without generating mission-ending frost. David Willetts, British minister for universities and science, called the achievement 'remarkable.' "

    This isn't a new concept, but there is reason to be excited about Sabre's prospects.

    Six-Second Science Fair Projects On Vine

    I really enjoyed this compilation of the best entries to GE's Six-Second Science Fair. Using Vine, entrants had to illustrate some scientific principle or show an experiment in the video-sharing tool's six-second format. I'm impressed the potato battery worked. (via Laughing Squid)

    The Science of Strike-Anywhere Matches

    The second episode of Wired's excellent "What's Inside" video series debuted earlier this month for YouTube's Geek Week--it's an animated look at how Diamond brand Strike-Anywhere matches work. Wired magazine explored the components that make up these magical matches back in 2009, though the science is much easier to understand in this slick video. Potassium Dichromate has never had such a spotlight.

    Optical Tweezers Inch Us Ever Closer to Tractor Beams

    Researchers at the University of Rochester demonstrate the ability of focused lasers to levitate very small objects in a vacuum. In this experiment, assistant professor of optics Nick Vamivakas focused a laser to a very small region of space in a vacuum, and then sprayed that space with an aerosol containing dissolved nanodiamonds--each as small as 100 nanometers (about one-thousandths the diameter of hair). The process, called laser trapping, is described in a paper published this week in the journal Optics Letters. It works because of the ability of light to exert push and pull forces on objects, a trait that we don't normally attribute to light because it doesn't affect us at human scale. Scientists have been able to use light to manipulate microscopic objects in the past using this optical tweezer technique, but this is the first time that nanodiamonds have been trapped by light.

    Photo credit: J. Adam Fenster/University of Rochester

    The video below explains the process in greater detail:

    Spacetime Cloak: Using Mirrors To Create Holes in...Time?

    "A spacetime cloak, or event cloak, is a means of manipulating electromagnetic radiation in space and time in such a way that a certain collection of happenings, or events, is concealed from distant observers," writes Miguel Lerma. This is his introduction to a simple device, mainly built from mirrors, that has the ability to cloak time. Or, as Technology Review writes, create holes in time. Which sounds both awesome and incredibly dangerous.

    Isn't this the kind of thing Back to the Future's Doc Brown warned us about? Can Lerma's device create some kind of world-rending time paradox? Well, not really. As dramatic as the term "spacetime cloak" may be, the actual effect of a spacetime cloak is more like an optical illusion, though it's an illusion with some rad science behind it.

    Photo credit: Flickr user fidelramos via Creative Commons

    Lerma's paper explains how a spacetime cloak typically functions: "An event cloak design using metamaterials...works by using a medium in which different parts of the light illuminating a certain region can be either slowed down or speed up. A leading portion of the light is speeded up so that it arrives before the events occur, whilst a trailing part is slowed down and arrives too late. After their occurrence, the light is reformed by slowing down the leading part and speeding up the trailing part. The distant observer therefore only sees a continuous illumination, whilst the events that occurred during the dark period of the cloak’s operation remain undetected."

    His device creates the same effect, but using a different method. The metamaterials mentioned in the excerpt above are expensive, but mirrors are cheap. Lerma writes "rather than slowing down and speeding up light, we manipulate an obscurity gap by diverting the light through paths of appropriate length with an arrangement of switchable transflective mirrors."

    By inserting a series of reflective mirrors between a light source and an object--like, say a clock--and then another series of mirrors between that object and a camera (or observer), it's possible to extend the length of time it takes light to travel from one point to another. Lerma's setup would use switchable transflective mirrors that can alternate between reflective and nonreflective states.

    By precisely controlling those mirror states, the spacetime cloak could completely obscure the object from the observer. Lerma writes that "Conceptually, a safecracker can enter a scene, steal the cash and exit, whilst a surveillance camera records the safe door locked and undisturbed all the time." However, as we understand the system, the obscurity gap only lasts as long as it takes the light to travel through the first series of mirrors. And given how fast light travels, you're going to need some serious distance to create a substantial time gap.

    Teleporting a Person to Space Would Take Approximately 4.85 Quadrillion Years

    Star Trek's fictional technologies have, over the years, driven some real scientific advances. Plenty of companies aspire to recreate Star Trek's tricorder, and Google is currently endeavoring to replicate the Enterprise's computer. But a bunch of physics students from the University of Leicester have nixed the possibility of Star Trek's most fantastic, longed-for technology: Teleportation.

    As Motherboard writes, it would take about 4.85 quadrillion years to teleport a human being into orbit around the Earth (quadrillion is the one after trillion). That's a pretty long time, considering we think of teleportation as a near-instant alternative to slower modes of transportation. By comparison, it only takes a few hours to fly from Earth to the International Space Station.

    Why is teleportation, as these physicists look at it, completely impractical? It comes down to two issues: the volume of data, and the speed at which we can send that data. Through quantum entanglement, teleportation is possible--sort of. We can recreate the quantum state of an atom that exists in one place in another place, effectively moving data. It actually sounds a bit like the teleportation in Star Trek, which breaks a person down into an energy pattern accurate to the quantum level.

    Photo credit: Paramount Home Video

    Turns out, people consist of a lot of data. "Breaking down a person by the DNA pairings in each cell, they found the total data for a human genome is 6x109 bits—billions of tiny particles," writes Motherboard. "But what really slows the teleportation process down is the human brain—all those facts, memories, song lyrics, Spanish verbs, and the rest of the information stored in the average person’s head. The brain added another 2.6x1042 bits that had to be beamed into space."

    Transporting all of that body-and-brain data using a 30GHz bandwidth, as outlined in the paper, would take about 4.85 quadrillion years, "making teleportation impractical."

    Impractical for now, anyway. In 4.85 quadrillion years, hopefully we'll have come up with something faster than the space shuttle.