Most invisibility cloaks under development actually make objects more visible overall, not less, scientists have revealed.

This novel finding points to ways researchers can develop better invisibility cloaks, investigators added.

Invisibility cloaks, once thought of only as "Star Trek" science fiction, or the province of certain boy wizards, work by smoothly guiding light waves around objects so the waves ripple along their original trajectories as if nothing were there to block them. Cloaking devices that work against other kinds of waves are possible as well, such as the acoustic waves used in sonar.

As exciting as the cloaks are, scientists know they possess a number of drawbacks. A major challenge is that the cloaks are usually limited to working against narrow ranges of wavelengths for various types of waves — a cloak deflecting microwave beams would likely not work against visible light.

To see if there was a way around this shortcoming, researchers explored how invisibility cloaks scatter light waves. Although cloaks may render objects invisible within a certain range of wavelengths, the scientists' calculations surprisingly revealed that all cloaking techniques available today actually scatter more light than uncloaked objects — essentially rendering objects more visible, not less — if one looked at visibility over all wavelengths. [Science Fact or Fiction: The Plausibility of 10 Sci-Fi Concepts]

For example, making an object invisible to red light may also make it bright blue, boosting its overall visibility. Assuming one looked at all wavelengths of light, one would actually see the cloaked object "more than the uncloaked object it is trying to hide," said study co-author Andrea Alu, an electrical engineer at the University of Texas at Austin. Alu and his colleague, Francesco Monticone, detailed their findings Oct. 21 in the journal Physical Review X.

Invisibility cloaks are generally made of artificial structures known as metamaterials, whose light-scattering properties depend on how these materials are built. Instead of using static, fixed materials to warp light as current invisibility cloaks do, the researchers suggest making future cloaks from active, dynamic components, such as a network of electronic amplifiers connecting an array of square metal patches on a surface. These electronic circuits can theoretically tailor cloaks to remain invisible over broad ranges of wavelengths depending on the incoming light waves.

"The most promising venue is to explore the ultimate limits of active cloaks, and how good of a performance we can achieve," Alu told LiveScience. "Our theoretical results in this venue appear very promising."

Alu and colleagues Pai-Yen Chen and Christos Argyropoulos will detail their findings on active cloaks in a paper accepted for publication in Physical Review Letters.

Follow us @livescience, Facebook& Google+. Original article on LiveScience.

• Now You See It: 6 Tales of Invisibility in Pop Culture
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SEE ALSO: Scientists Invent An Invisibility Cloak That Can Hide Data In Time

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Scientific American editor Clara Moskowitz has a nice post showcasing some of the big questions asked by participants at a recent particle physics conference. 

These are the kinds of questions that make scientists worry and keep the midnight oil burning at institutes and labs around the world. As relevant as the questions were they all dealt with particle physics.

Here I want to note five other important questions that (should) keep physicists awake during the night.

Some of the questions deal with mundane but important issues of science funding, others lie at the intersection of physics and other sciences and yet others probe the very nature of reality. These are not the only questions I can think of but they are certainly some of my favorites.

1. Will we ever understand quantum mechanics?

Richard Feynman famously quipped that “I can safely say that nobody understands quantum mechanics”. The situation has not fundamentally changed since Feynman’s time, but the question has become even more pressing. This is because no other scientific theory presents such an enormous gap between successful prediction and deep understanding as quantum mechanics. Starting in the 1970s, some of the most bizarre implications of quantum theory – most prominently the “spooky” (in Einstein’s words) phenomenon of entanglement – have been verified by precise experiments. Last year’s Nobel Prize was awarded in part for using these strange properties to trap ions and atoms.

And yet we have no clue how any of the fundamental facts of quantum mechanics including wave-particle duality, entanglement, quantum tunneling or the double-slit experiment – that disarmingly simple setup which, in Feynman’s words, contains “the only mystery of quantum mechanics” – actually work. The quantum world continues to be a fairyland that defies common sense and where anything can happen. For decades most physicists have used quantum mechanics, but nobody has convincingly shown us where it comes from. Einstein may have gone against the grain of experiment but he was right in feeling a decided sense of unease regarding the reality which the weird quantum universe encapsulates. Narrate the parable of Schrodinger’s cat and you will be met with laughs and smirks, but the laughter cannot obliterate the deep anguish of physicists, a feeling that their most successful theory of nature is, at its deepest level, a hazy ball of mist.

Since the theory was first developed there have been dozens of alternative interpretations of what it all means, from the classical Copenhagen interpretation to the simple but mind-bending many-worlds interpretation of Hugh Everett. And yet we are no closer to teasing out a winner among these bold conjectures. Perhaps our only flaw is in trying to use ordinary common sense to grok what is fundamentally an otherworldly universe that does not lend itself to our frail minds. Perhaps we should continue to “shut up and calculate”, reap the tremendous agreement with experiment that the theory gives us and just stop bothering about what it all means. What we do know is that physicists and philosophers will keep on searching for the true reality underlying quantum mechanics, whether one exists or not.

2. Will we ever be able to detect single gravitons?

Gravitons are hypothetical elementary particles that mediate the force of gravity within the framework of quantum field theory. Their existence is necessary for forging a meld between quantum mechanics and Einstein’s general theory of relativity, a quest that has been going on for fifty years. This quest has produced reams of equations and elegant experiments with no definitive answer (it’s worth noting that the search for individual gravitons is different from the search for gravitational waves, a purely classical endeavor). LIGO and LISA are only two of the more ambitious projects designed toward this goal. Until now none of these experimental setups have been able to detect gravitational waves, but with individual gravitons it might be a completely different ball game.

Over the last few years Freeman Dyson, Tony Rothman and Stephen Bough among others have written papers demonstrating that it might be impossible to detect single gravitons if anything resembling realistic physics is taken into account. They have analyzed existing approaches and concluded that the scale of the experimental apparatus in these approaches might have to approach absurdly unrealistic limits if they are to successfully detect gravitons. Gravity thus might remain a statistical bulk property like temperature or pressure, irreducible to the properties of individual particles. If this is indeed true there might forever be an ‘iron curtain’ of ignorance erected between the quantum and classical worlds. It’s a possibility that is maddening, and one that should certainly keep any physicist with even a modest ambition of unifying the known forces of nature awake.

3. Will we ever understand emergence?

In 1972, Nobel Laureate and brilliant “curmudgeon” of physics Philip Anderson lit a firecracker and threw it into the basement of the temple of reductionist physics. In a Science article titled “More is Different” Anderson underscored how the difference between understanding the behavior of individual particles  – something that physics has wildly excelled at – and collections of particles is not just quantitatively different but qualitatively so. In his article Anderson was appealing to the universal phenomenon of emergence, a term that’s often loosely thrown around but which is very much real. Simply put, emergence refers to the fact that the behavior of groups of entities cannot be predicted from the behavior of the individual entities alone.

Emergent phenomena bestride our world, from the properties of metals to termite nests to flocks of starlings to the global economy. In one sense all of chemistry, biology and sociology is a hierarchical clustering of emergent behavior. Physics has failed to explain this central and deep mechanism in the workings of the natural world. In fact as Anderson has noted, physics cannot explain emergence even in its own narrow domain, for instance in the field of superconductivity. Eighty years ago Paul Dirac noted that the laws of physics as then understood could explain “most of physics and all of chemistry”. And yet we don’t understand how to make the logical leap from the behavior of a quark to the behavior of a strand of DNA composed of multitudes of quarks. Understanding emergent behavior may be the single most important goal for physicists if they want to understand how physics connects to other sciences and to the human world. Without a grasp of emergence physics will remain a narrowly understood and applied science, of scant use to other practitioners.

4. How will we keep particle physics alive?

This is a question which is as social as it is scientific, and yet it is one that should keep particle physicists worried and awake. Last year in the New York Review of Books, Steven Weinberg noted that the biggest discovery at the LHC might not be the Higgs boson but in fact would be something unexpected, something that really overturns our knowledge of the universe as enshrined in the Standard Model. To make this discovery we would probably need to go to even higher energies, which in turn would entail even bigger particle colliders likely costing tens of billions of dollars. What is worse is that it might be impossible to do these kinds of physics experiments using cheap equipment and small teams.

In the face of economic downturns, political gridlock and widespread public embrace of pseudoscience it will be a tremendously uphill battle for particle physicists to expect support for the next multibillion-dollar physics experiments. The long history of failed projects like the SSC and even successful ones like the Hubble Space Telescope demonstrates the careful coalition building, favorable economic forces and political wisdom that need to align for taking a Big Physics experiment all the way to success. When it’s all over it looks streamlined and obstacle-free, but the fact is that a single item demoted in Congress’s budget can kill such dreams. The lack of support for Big Physics projects in particle physics and the impossibility of practicing their trade on a smaller scale might mean that an entire generation of particle physicists is unable to pursue the biggest mysteries of their field. It’s a thought that should keep practitioners in the field very worried indeed.

5. Will physics help us understand the nature of consciousness?

This is a question that’s somewhat related to question 3 above but its profound significance makes it deserve separate discussion. Beyond understanding things like the origin of the universe, understanding the origin of the very consciousness that allows us to understand the origin of the universe is rightly regarded as the most important question in science. We are quite certainly a long way from even attempting to answer it, but neuroscience is a young and vibrant discipline full of exciting possibilities. The physics question about the brain which we want to answer is: Is there more or less direct evidence of the principles of quantum mechanics operating in the workings of the brain at multiple levels, from neurons to behavior. In one sense this question is asking what it exactly is that connects the micro world to the macro world, a line of investigation going back to the beginnings of science.

At least a few scientists have tried to make a dent in the question. A few years ago Roger Penrose and Stuart Hammerof proposed that the switching of protein assemblies called microtubules in the brain could be seen as a direct example of the entangled superposition of elementary particles. This provocative thesis however received a major blow from the work of Max Tegmark who demonstrated that at ordinary temperatures any kind of particle entanglement in the brain would undergo very rapid decoherence, a kind of averaging out that would essentially sever the entangled states-observable biochemical properties connection. But the question seems far from settled; other work has demonstrated links between superposition and important phenomena like photosynthesis and electron transfer in proteins. Perhaps one day we will be able to explain how memory forms at the molecular level because of entanglement. Or perhaps explaining consciousness will be inherently impossible, as some physicists like Edward Witten seem to think. Either way, there is no doubt that contemplating the connection between physics and consciousness is one of the foremost conundrums that physicists will keep dreaming about.

SEE ALSO: The 5 Most Important Physics Discoveries Of The Past 25 Years

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They call themselves "wizz kids."

Todd Truscott and Randy Hurd of Brigham Young University's Splash Lab, a research lab studying the physics of fluids, have been using high-speed cameras to examine exactly what happens to a stream of urine when it hits the toilet.

They're on a quest against "splashback," simulating male urination in the lab (using this apparatus) to see how exactly you can go about getting it all in the bowl. For the sake of clean bathrooms, clean pants and happy subsequent bathroom-goers.

According to Hurd, part of the messiness caused by male urination is due to a phenomenon called Plateau-Rayleigh instability, which causes streams of falling liquid to decompose into droplets. When a guy pees, the urine stream breaks into droplets about 6 inches away from the urethra exit. "So by the time it hits the urinal, it's already in droplet form," he told the BBC. "And these droplets are the perpetrators of the splash formation on your khaki pants."

The best way to avoid unwanted urine splash seems to be sitting on the toilet, a technique that has been advocated by certain restaurants, Taiwan's Environmental Protection Administration minister, and one Swedish politician, and shouted down by manycorners of the Internet. You're about five times farther from the bowl when you stand as when you sit, creating a bigger splash, but if standing to pee is essential to your manhood, Hurd says that you can also switch the "angle of attack," so to speak. Smaller angle between stream and toilet water, less splatter. Even better, hit the porcelain instead of the water, which Hurd says makes the process "a lot less chaotic."

The Splash Lab will be presenting its research at the American Physical Society Meeting later this month. Now watch this mesmerizing video summarizing the fluid dynamics of urine splatter:

SEE ALSO: Sarah Silverman Tweeted A Weird Question About Peeing, And We Found The Answer

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Normally, to make water roll off surfaces we spray them with toxic chemicals, like Rust-Oleum's NeverWet, which contains acetone (nail polish remover), liquid petroleum gas, and a few additional "magic" ingredients.

But some surfaces aren't safe for chemical spray — like things we want to eat off of or are near children. Instead of using chemicals, we can design surfaces that naturally repel water. Because of their texture, these surfaces completely shed water instead of absorbing it.

Researchers from MIT designed a new, even better textured surface that stays completely dry. The paper was just published in the journal Nature.

Without the texture, the hydrophobic surface acts like a lotus leaf. It traps air on the surface, which provides a buffer between the actual surface and the water droplet. Although a droplet of water will roll right off, it will still flatten completely against the surface (allowing time for the surface to absorb some of the water) before retracting into a ball and bouncing off.

Scientists realized if they could make the droplets break up into smaller drops instead of flattening into a pancake, the water would be in contact with the surface for a much shorter period of time, meaning there's less of chance of the water absorbing into the surface.

They did this by adding microtextures to an already hydrophobic surface. These microtextures redistribute the water and break up the flattened pancake of liquid so it can't form back into a drop.

Here's a comparison of the two surfaces, with and without microtextures:

One application, the researchers say, is in aircraft. It works so quickly that even in super-cold environments the water doesn't stick long enough to freeze. By making the surface of the engines repel water before it ices up, they could potentially reduce the amount of frost that builds up.

Here's a quick Nature Video on the development:

They went looking in nature and realized that a very similar pattern is used on butterfly wings and the leaves of the nasturtium plant, which also have ridges to break up droplets.

This is just one example of bio-mimicry, a growing field of engineering and other sciences in which researchers are looking to nature for inspiration.

SEE ALSO: The Incredible Science Behind How Nature Solves Every Engineering Problem

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If you believe 'The Matrix' franchise, what we think is our everyday life is in fact a simulation generated by an all-powerful computer.

However this idea may not simply be science fiction — "cosmic rays" could reveal that we are indeed living in a simulated universe.

According to Discover magazine, physicists can offer us the ability to test whether we live in our own virtual Matrix by studying radiation from space.

Cosmic rays are the fastest particles that exist and originate in far-flung galaxies. They always arrive at Earth with a specific maximum energy of 10 electron volts.

If there is a specific maximum energy for particles then this gives rise to the idea that energy levels are defined, specific, and constrained by an outside force.

Thus, according to the research, if the energy levels of particles could be simulated, so too could the rest of the universe.

The "cosmic ray test" was developed by Silas Beane, a nuclear physicist at the University of Washington, and involves scientists building up a simulation of space using a lattice or grid.

They calculated that the energy of particles within the simulation is related to the distance between the points of the lattice and that the smaller the lattice size, the greater the energy that the particles can have.

There have been many efforts to discover the truth about the universe and simulated reality.

In 2003 philosopher Nick Bostrom put forward the idea that we may live in a computer simulation run by our descendants. It was Beane and his colleagues who suggested that a more concrete test of the simulation hypothesis should be carried out.

Last year Beane told of his plans to recreate a simulated reality using mathematical models known as the lattice QCD approach.

If we do indeed live in a simulated universe akin to 'The Matrix,' Beane has a warning.

He told the magazine that the "simulators" who control our universe may well be simulations themselves; a "dream within a dream" type effect that could render the entire scientific study meaningless:

If we're indeed a simulation, then that would be a logical possibility, that what we're measuring aren't really the laws of nature, they're some sort of attempt at some sort of artificial law that the simulators have come up with.

Some academics are skeptically of the "Matrix theory." Professor Peter Millican, who teaches a philosophy and computer science degree at Oxford University, believes it could be ultimately flawed.

The theory seems to be based on the assumption that "superminds" would do things in much the same way as we would do them. If they think this world is a simulation, then why do they think the superminds — who are outside the simulation — would be constrained by the same sorts of thoughts and methods that we are?

They assume that the ultimate structure of a real world can't be grid like, and also that the superminds would have to implement a virtual world using grids. We can't conclude that a grid structure is evidence of a pretend reality just because our ways of implementing a pretend reality involve a grid.

Professor Millican did, however, add that he believed it was beneficial to conduct research into such theories.

It is an interesting idea, and it's healthy to have some crazy ideas. You don't want to censor ideas according to whether they seem sensible or not because sometimes important new advances will seem crazy to start with.

You never know when good ideas may come from thinking outside the box. This matrix thought-experiment is actually a bit like some ideas of Descartes and Berkeley, hundreds of years ago. Even if there turns out to be nothing in it, the fact that you have got into the habit of thinking crazy things could mean that at some point you are going to think of something that initially may seem rather way out, but turns out not to be crazy at all.

SEE ALSO: Scientists Announce First Evidence Of Dark Matter

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Scientists using a telescope buried under the Antarctic ice sheet have found the first sign of high-energy neutrinos that come from outside the solar system. The discovery is a huge step to finding the source of cosmic rays — high-energy particles that speed through space and appear to come at Earth from all directions.

The details of the study will be published in the journal Science on Friday, Nov. 22.

The origin of cosmic rays, and what could be accelerating the particles in them, has been a mystery since their discovery more than 100 years ago. That's partly because cosmic rays are electrically charged, and as a result, the particles get deflected from their original track as they interact with the magnetic fields in space. The particles travel across the galaxy in looping paths that make it nearly impossible for detectors on Earth to trace where cosmic rays come from.

But neutrinos are different. A neutrino is one of the fundamental particles that make up the universe. The nearly massless particle has no electric charge, and is therefore not affected by magnetic fields.

Neutrinos are everywhere — zipping through our bodies and entire planets right now — maintaining their speed and direction as they strike Earth at the speed of light. Once neutrinos get here, they are still tough to detect because they interact weakly with other particles. But if observed and confirmed, the particles can act as pointers to the place where they originated since they move in a straight line.

Previously, scientists have observed low-energy neutrinos that originate in Earth's own atmosphere. The IceCube Neutrino Observatory was designed to look for high-energy neutrinos — those that come from the outer reaches of our galaxy and beyond. Detecting these neutrinos would be the first solid evidence of neutrinos coming from cosmic sources, like exploding stars, gamma rays bursts, or black holes, that are millions, or even billions of light years from Earth.

IceCube has been scanning for high-energy neutrinos since 2010, using thousands of sensors placed inside a cubic kilometer block of ice located a mile below the surface. As neutrinos pass through and collide with atoms inside the ice, they sometimes give off other charged particles. The charged particles will give off light as they travel through the ice. The telescope detects this light.

Most neutrinos that IceCube detects come from the Earth's atmosphere and are not of interest to scientists studying cosmic rays. But in the summer of 2012, team members reported two neutrinos with energies above what would be expected if they came from the atmosphere.

Looking back through their records, scientists found 26 more super-energetic neutrinos, including the most energetic neutrinos ever observed.

These particles have the characteristics that scientists predict of neutrinos that come from extraterrestrial sources.  

The new research still doesn't solve the riddle of where cosmic rays come from — more observations are needed to trace the high-energy events back to any one location, Gregory Sullivan, a physics professor who led a team of researchers from the University of Maryland, said in a statement.

But the finding proves that IceCube has the ability to see these high-energy events, and this sensitivity will improve as new and better neutrino detectors are put to work. "The era of neutrino astronomy has begun," Sullivan said.

SEE ALSO: Here's What Mars Looked Like 4 Billion Years Ago

SEE ALSO: Astronomers Spot A Never-Before-Seen Comet-Like Thing In The Sky

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Tapping on the top of a newly opened beer bottle can create a foamy eruption of booze — and get you disinvited from future house parties. Now, physicists have explained this beer bottle phenomenon, and it all comes down to bubbles.

Here's how it works:

A sudden, vertical force against the top of the beer bottle creates a compression wave through the glass, much like the sort of wave you get when you knock one end of a stretched-out Slinky toy. When the compression wave hits the bottom of the bottle, the wave transmits its force back up through the liquid as an expansion wave.

While compression waves compress the beer as they travel through, causing pressure, temperature and density to increase, expansion waves do the opposite, decreasing pressure, temperature and density in the liquid. [Raise Your Glass: 10 Intoxicating Beer Facts]

Now, once the expansion wave hits the surface of the beer, located up by the top of the bottle, it bounces back as a compression wave again. The result is a "train" of expansion and compression waves, all bouncing back and forth between the bottom and top of the bottle, fluid mechanics researcher Javier Rodriguez-Rodriguez of Carlos III University of Madrid in Spain reported on Sunday at the annual meeting of the American Physical Society's fluid dynamics division in Pittsburgh.

This train of waves causes a big mess. In response to the compression and expansion forces pushing and pulling it every which way, the beer undergoes cavitation, or forms bubbles. Cavitation occurs in response to rapid pressure changes in a liquid, and is important in the engineering of ship propellers. Since these propellers cause cavitation as they spin, the formation and collapse of the bubbles puts chronic stress on the metal.

Cavitation also explains another party trick, in which the bottom of a bottle can be made to explode by hitting the top.

In the case of beer, cavitation creates large bubbles, which rapidly collapse. The collapse of these "mother" bubbles creates multiple, smaller "daughter" bubbles.

These daughter bubbles are the reason the frat-boy prank of tapping on a bottle ends in disaster. The small, carbonated bubbles expand rapidly and gain buoyancy, acting as a life raft for the surrounding liquid. The result is foam, and lots of it.

"Buoyancy leads to the formation of plumes full of bubbles, whose shape resembles very much the mushrooms seen after powerful explosions," Rodriguez-Rodriguez said in a statement. "And here is what really makes the formation of foam so explosive: The larger the bubbles get, the faster they rise, and the other way around."

Explaining this phenomenon may make you the life of your next party, but Rodriguez-Rodriguez and his colleagues studied beer in order to understand bigger-picture gaseous eruptions. One example is the Lake Nyos disaster in Cameroon. Volcanic activity under this lake dissolves carbon dioxide in the water. In 1986, the lake rapidly degassed a large amount of carbon dioxide all at once, suffocating 1,700 people and thousands more livestock. This rapid degassing event, possibly caused by a landslide, could share similar physics with an erupting beer bottle.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook& Google+. Original article on LiveScience.

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What looks like a lost Santa beard or fallen cotton candy in the forest in the images below is actually an amazing natural phenomenon called Frost Beard or Hair Ice. It occurs because of a bacteria that causes growth of these fluffy ice hairs.

The images below were taken by Environmental Scientist Sarah Boon for her blog Watershed Moments. She says in the blog post that she found them on alder shrubs, which contain a lot of moisture. They appeared just after the temperature dropped below freezing.

A bacteria called pseudomonas syringae lives in these shrubs and other plants and serves as a starting place for the ice crystal. It also raises the freezing temperature for the water in the plant, so the water in the plant freezes before the water around it. The water in the plant's vessels expands and seeps through cracks into the cooler outside air, where it freezes.

Look, it's incredible:

See more of Boon's images on her blog >

You can read more about frost beards and other plant-related ice action at this post from the Cocktail Party Physics blog>

SEE ALSO:  These Mesmerizing Photos Of Snowflakes Were Taken With A Regular Point-And-Shoot Camera

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This is a great party trick, or great if you just want to pretend you're a wizard or a water-bender. You can instantly freeze an entire bottle of water. Grant Thompson put together this awesome video to explain how it's done.

The secret is supercooling the water first. To supercool something, it has to reach a temperature below its freezing point while staying in a liquid form. Normally when water drops below 32 degrees Fahrenheit, it freezes and turns into ice.

But if the water is pure enough and there aren't any imperfections in the container holding it, the water will get stuck in its liquid state. That's because ice crystals need what's called a nucleation point in order to form. This nucleation point can be any kind of impurity in the water, like a speck of dust. Then, the ice crystal is the starter for more ice crystals — expanding the crystals exponentially.

This supercooled liquid state is not very stable either. All it takes is a jolt to align water molecules in a way that make the ice crystals start forming. They fill the entire bottle in seconds:

You can also start the freezing process by dropping a piece of ice into the water. The ice cube acts as a nucleation point because ice crystals like to pack themselves onto an ice crystal that's already formed. You can see how dropping a piece of ice into a glass of supercooled water makes the whole glass freeze in a few seconds.

You don't even have to drop the ice cube all the way in. All it takes is touching the very tip of a piece of ice to the water and the ice cube will freeze in place:

It works the same way if you pour the supercooled water on top of ice. The ice crystals pack on top of each other as you pour and you can make an instant ice tower:

Add some flavoring and make your own instant snow cone:

You might have to experiment a little to find the ideal time to leave your bottles in the freezer: the time will vary depending on how cold the freezer is and how big the bottles are. We tried it previously with some sodas and the bottles froze unevenly and didn't give us the awesome water-to-ice-immediately effect. 

SEE ALSO: Super Cool Your Soda To Make A Slushie In Seconds

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You can make a gravity-defying liquid just by mixing a molecule called polyethylene oxide and water. The BBC show Quite Interesting explained how it works. The mixture even glows under UV light.

Polyethylene oxide works like a siphon, which makes water flow uphill by a combination of pressure and weight differences.

Liquid flows from high pressure to low pressure. The weight of the water above creates this pressure, so the pressure at the bottom of the column is higher than that at the top.

The weight of the water pushes the liquid out of the bottom of the column

Weight plays a role since the water in column C weighs more than column B. Its heavy enough to pull the water out of container A into container D.

Polyethylene oxide creates a siphon effect when its mixed with water because it forms a gel-like mixture when hydrogen bonds form between the oxygen atoms of the polyethylene oxide molecules and the hydrogen atoms of the water. This helps pull the liquid out of the top vessels because the molecules form long chains.

The gel pulls itself upwards because the stream flowing down into the bottom vessel weighs more than the stream flowing up.

The resulting gravity-defying liquid is used to thicken things like shampoos, conditioners, and lotions. You can watch the full video below if you don't mind a little crude humor. The video was posted to YouTube by the BBC.

SEE ALSO: Gravity-Defying Cat Jumps Up Walls In Slow-Motion

SEE ALSO: This Mesmerizing Video Will Convince You That Physics Can Be Fun

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Time travel is a mysterious and so far unproven phenomenon in physics.

But just because time travel can only be observed in science fiction, doesn't mean it isn't possible: some people think that time travelers from the future could already be visiting us now.

Scientists from Michigan Technological University searched the Internet for time travelers and published their results in the physics pre-publication database arXiv on Dec. 26. They looked specifically for social media posts that seemed to predict the future — mentioning events before they happened.

While they didn't find any, Doctor Who and Back to the Future fans need not worry: the results don't disprove time travel.

This was not the first attempt by scientists to find time travelers. In May 2005, a grad student at MIT advertised for, and subsequently held, a convention for time travelers. Unfortunately no one from the future showed up.

The scientists who worked on this paper used a slightly more sophisticated method: they searched the Internet for content that "should not have been known at the time it was posted."

They used this method to search twitter, search engines, and the Astronomy Picture of the Day website.

The search terms

The scientists decided what search terms to use based on a few criteria:

1. They needed a search term that acquired a name between the period of January 2006 (because they were planning on using Twitter, and Twitter was established in 2006) and September 2013.
2. They needed a search term with a unique label that wouldn't turn up lots of closely related results.
3. They needed a search term that would remain important in the future that time travelers would still be likely to communicate about.

Eventually they decided on "Comet ISON" and "Pope Francis." They looked for any posts that existed about Comet ISON before it was discovered in September 2012, and any posts about Pope Francis before he was officially named the pope in March 2013.

They did not find any. The researchers then sent out a request to any existing time travelers to post something proving time travel would become possible in the future and if it would be possible for time travelers to change the past.

Specifically, "time travelers were requested to respond with a communication including either the hashtagged term "#ICanChangeThePast2" or "#ICannotChangeThePast2" on or before 2013 August."

The researchers used Twitter for this request because tweets cannot be backdated, so no one but a legitimate time traveler would be able to pull this off.

Time travelers could technically still be around

The experiment did not yield any time travelers, but the researchers outlined several possible reasons for this:

1. It may be physically impossible for time travelers to leave any lasting remnants of their stay in the past.
2. It may be physically impossible for us to find such information because it would violate some yet-unknown law of physics.
3. Time travelers may simply not want to be found, and cover their tracks well.
4. Time travelers might have not used those specific event tags.
5. And of course, the researchers could have just missed them due to human error, non-comprehensive Internet searches, or inaccurate content time tags.

Either way, this is the most comprehensive search for time travelers ever conducted.

SEE ALSO: If You Ever Get The Chance To Time Travel, These Are The 5 Things You Need To Google

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Forget superconductors and magnetic fields. Scientists from the University of Tokyo have developed a way to use sound waves to levitate objects and move them around midair.

When a sound wave travels through air, it compresses air molecules as it rolls along its way. It creates a wave of pressure as it travels from a speaker through a room. One sound wave just vibrates forward through the air, but if you hit one sound wave with another traveling in the opposite direction, the two waves can combine and create a standing wave. This standing wave has points along it where the air compression is traveling in opposite directions and slam into each other creating points called nodes.

So to levitate an object, the researchers created a standing wave and dropped the object between those opposite directions of air pressure. The currents coming from opposite directions will hold the object in midair at the node of the wave, like in the image below:

Sadly, this does not mean we're about to have hoverboards; if you look at the equation of the wave and do the math, the setup can only support very small and very light objects. Also, these sound waves have to be finely tuned to hover and move the object.

Scientists have been able to levitate small objects using sound waves for a few years now, but now the researchers have shown that they can actually move the objects around in three dimensional space instead of simply hovering it in a stationary position.

The group of scientists from Tokyo University developed a way to control the sound waves and actually move the nodes of the wave around, moving the small objects with them. It really looks like magic:

The particles are manipulated using speakers that send two sound waves at each other from opposite directions.

The speakers actually do not produce any noise — at least not at the pitch that the human ear can hear. In the GIF below you can actually see what the standing wave looks like as the scientists levitate a piece of dry ice. The white gas flowing off the ice shows where the waves are:

The scientists can even just toss these small balls onto the standing wave and have them float there — you can see  below that some of them get trapped in the nodes of the wave on their way down.

The details of the experiment are published in the open access pre-publication database arVix. You can watch the entire video below.

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Migratory birds flying in a "V" shape flap their wings at precise times to take advantage of the lifting power generated by the bird in front, scientists report in a study published Jan. 15 in the journal Nature.

The theory that birds fly in a V-formation to save energy is not new. But this is the first time scientists have recorded data from birds flying in the wild, thanks in part to new technology.

British scientists attached sensors to 14 northern bald ibises to track their movements during a 43-minute period of a migratory flight from Austria to Italy. 

When a bird flaps its wings, it creates lift by generating a looping motion of air around the wing.

The airflow blowing over the top of the wing is thrown downward, known as downwash (shown in red in the graphic below), while the air at the wing's tips is accelerated upwards, known as upwash (shown in blue).

The birds want to be in the region of upward-moving air to reduce the effort needed to fly.

Birds not only position themselves in the best possible spots to take advantage of the upward flow of air, researchers from the Royal Veterinary College in London found, they are also paying attention to the timing of the flap movements of the bird ahead, "which create tip vortices that undulate up and down," Florian Muijres and Michael Dickinson wrote in a News & Views commentary on the study, also published in Nature.

A bird will alter the timing of its wing beat to stay in the upwash created by the moving wingtips of the bird ahead of it.

"A bird that is following another bird must carefully adjust its own flapping motion, not in perfect temporal synchrony with the leader, but rather at a precise phase lag that tracks the tip as it oscillates," Muijres and Dickinson write.

To do all those things, the best way for the birds to fly is in a V- shape.

Check out the video below for more on why birds fly in a V-formation.

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A chain of beads can defy gravity, acting like water spouting from a fountain, and now physicists reveal the secret behind this odd phenomenon.

The findings could have surprising implications for everything from tethered satellites to elevators reaching from space to Earth.

Chains are among the simplest, oldest and most widespread of technologies. As such, one might imagine scientists comprehensively understood their behavior.

However, a recent online video of a chain from the BBC seen by more than 2.5 million viewers astonished many, including many physicists. The video shows a strange effect one can easily recreate at home — if one lays a long chain of beads in a neat pile within a pot, beaker or similar vessel, pulls an end of the chain over the rim of the vessel and then releases it, the chain will not only flow to the floor due to gravity but also spontaneously arc upward as it moves. [See Videos of Weird Phenomenon of Beads Forming a Fountain Macaroni Fountain]

Chain physics

Scientists were launching a project to teach physics to high school students, the Rutherford School Physics Partnership, when they discovered this video.

"We thought it was cool, and thought we should figure out what was going on and set up a question of it for the high-school students," said study lead author John Biggins, a physicist at the University of Cambridge in England."It then quickly transpired that we couldn't explain the leaping of the beads above the pot using the traditional ways of thinking about chains being picked up and put down, and that to explain it we were going to have to revisit apparently set-in-stone ideas from textbook classical mechanics.

"This was the point we realized that we had an interesting research problem on our hands."

Although the weight of the chain clearly pulled it downward, scientists didn't know why the beads leapt upward before falling. Viewers of this event sometimes mistakenly believe "that the beads are magnetic in some way," Biggins said. But "magnetism has nothing to do with this phenomenon."

In addition, "many have speculated that the chain is forced to exit the pot in an upwards direction but needs to ultimately fall to the floor. So it is no surprise that it rises a distance above the pot, because it takes beads on the chain time to reverse their momentum, much in the way a ball thrown up rises then falls," Biggins said. "An even more subtle version of this misapprehension is that as the chain moves around the apex of the fountain, it moves in a curved trajectory."

However, both of these ideas "are fundamentally wrong," Biggins said.

Since their calculations showed the driving force behind this effect did not come from the part of the chain flowing away from the vessel, the scientists deduced that the force causing the beads to leap upward ultimately came from the pile of chain within the vessel somehow pushing upward.

"The push from the pot is the main result and the big surprise," Biggins told LiveScience.

Connected rods

The key to understanding where this push comes from is the fact that chains are essentially series of connected links or rods. Imagine that a rod in the pot is lying horizontally, waiting to move. It then gets pulled upward by a force acting on one of its ends. This force comes from the part of the chain flowing away from the vessel. [The 9 Biggest Unsolved Mysteries in Physics]

If this rod were alone, the force it experiences on one end would make it lift and rotate, causing the other end to move downward. However, since the rod is connected to other rods, "the far end of the rod bounces off the pot or other links in the chain, and this bounce provides the anomalous push," Biggins said.

"It is rare in physics for schoolchildren to be able to understand real research results, but in this case we think they will be able to," Biggins added.

Although the scientists conducted this research solely due to curiosity, the results "might have engineering implications," Biggins said. "People deploy chains and strings from piles all the time in a wide range of industrial and technological situations."

For instance, textile manufacturing often involves strings released from spools. In addition, satellites and spacecraft often deploy items on tethers.

"In situations like space engineering where energy and mass need to be reduced as far as possible, it may be advantageous to harness this push in the deploying of chains and tethers," Biggins said. "For example, if you want to tether two satellites, you need to deploy a chain between them from a pile on one satellite.

"Our work says that when you deploy that chain, by pulling on its end, your pull is supplemented by a push from wherever the chain is stored. So the pull you provide can be smaller than you originally thought. Therefore you can deploy the chain with a smaller force, and hence with a smaller, lighter motor and with less consumption of energy."

In what may be the most far-out possible application, the researchers also noted that plans to construct space elevators — giant structures reaching from space to Earth — often involve incredibly long fibers unspooled in space to stretch down to Earth. These findings could help complete such megastructures.

Biggins and his colleague Mark Warner detailed their findings online Jan. 14 in the journal Proceedings of the Royal Society A.

Follow us @livescience, Facebook& Google+. Original article on LiveScience.

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A huge mathematical breakthrough might have just been made, but a language barrier is slowing things down.

New Scientist reports that Kazakh mathematician Mukhtarbay Otelbayev may have solved an extremely difficult and useful mathematics problem: the Navier-Stokes equations.

This is one of the Clay Mathematics Institute Millennium problems — six unsolved problems (and one solved problem) that are both of deep theoretical interest and have many useful applications. Finding a solution to one of these problems that stands up to strict mathematical scrutiny carries a prize of one million dollars.

Unfortunately, in addition to the normal difficulties in verifying a complicated new proof, Otelbayev's paper is currently only published in Russian, making things a little harder for the international mathematical community.

The Navier-Stokes equations are a set of differential equations. Differential equations describe a quantity in terms of how it is changing throughout time and space. In many situations in physics and economics, it is more intuitive to describe mathematically how a quantity is changing than to directly write out an expression for the quantity itself.

But when you solve a differential equation you do just that — you find a formula to describe the actual quantity at any particular time or place, based on the differential equations describing how the quantity changes.

Solving the Navier-Stokes differential equations is key to understanding fluid dynamics — how smoke moves off of a fire, how water flows through a pipe, or how air glides over a car driving down a highway.

The equations describe how the flow of a fluid changes at different times and places. They are based on Newton's second law of motion— the statement that the amount of force exerted on an object equals the rate at which the object's momentum is changing — applied to the special case of a moving fluid.

Despite the relative straightforwardness of the equations, and their many applications, mathematicians do not know, in general, how to solve them. That is, given a fluid, we do not, in all cases, know how to find a mathematical expression that describes the patterns of flow in that fluid.

Mathematicians and physicists are especially confounded by the behavior of turbulent fluids, like the smoke spreading out chaotically on the table in the GIF to the right.

While we can use powerful computers to come up with approximate simulations of fluid behavior, without exact solutions to the Navier-Stokes equations, our theoretical understanding of these kinds of processes remains very limited.

Mathematicians do not even know whether or not these solutions exist, and this mystery, combined with the many applications of these equations to physics, is why this is such an important problem.

Time and the tireless efforts of many translators and mathematicians will tell if Otelbayev has truly solved this intriguing problem.

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Eighty years after they were first theorized, scientists have just created an artificial magnetic monopole.

Monopoles were first conceived in their modern form more than 80 years ago by Paul Dirac, one of the founders of quantum mechanics.

This discovery has some powerful implications for physics.

Magnets — how do they work?

Every magnet that we have ever observed is a dipole — it has both a north and south pole. If we draw magnetic field lines around a magnet, we always see the lines curve around, joining the two poles.

If you cut this magnet in half, you are not left with one north magnet and one south magnet, but instead two new double-poled magnets.

This goes on and on to the atomic level — you can keep cutting the magnet apart, but each part will still have two poles. Even a single spinning electron has both a north pole and a south pole.

That is how every magnet we have ever seen or experienced works.

Until now.

Now, researchers at Amherst College in Massachusetts and Aalto University in Finland have created a mysterious Dirac monopole in the lab.

The monopole acts as a single-point source for a magnetic field. The magnetic field lines stretch out from the monopole in all directions, without the looping back seen in a normal dipole.

Before the latest finding, researchers searched high and low but never found a magnetic monopole in nature.

Monopoles for other physical forces are ubiquitous in nature — electric monopoles exist all over the place. The protons and electrons that are some of the basic building blocks of matter generate electric fields centered on themselves without a corresponding opposite pole.

Finding the elusive monopole

The researchers used some high-tech lab work to create their artificial magnetic monopole, which they published Jan. 30 in the journal Nature.

Their first step was making a Bose-Einstein Condensate — a small cloud of atoms cooled to a few billionths of a degree above absolute zero.

The cooling process involves shooting atoms in a cold gas with lasers, sapping the atoms of their momentum, and then carefully manipulating the atoms with magnetic fields to slow them down even further.

At this temperature, the atoms are almost stationary, and weird quantum effects start to happen. The atoms begin acting very strange and form a new kind of matter — different from the solids, liquids, and gasses we are used to.

The researchers then carefully applied finely tuned magnetic fields to the strange matter, forming tiny tornado-like vortexes in the fluid.

This animation, taken from a YouTube video posted by the researchers at Aalto University, shows how the monopole is made. By carefully balancing out external magnetic fields to move a point at the base of a vortex into the middle of the condensate, the condensate itself begins to emit an outward pointing monopole-style magnetic field.

The researchers call this the "hedgehog configuration."

The mathematics that describe the theoretical behavior of the Dirac magnetic monopole very nicely line up with what this matter looks like in the hedgehog condition, the researchers said.

What's it all mean?

Being able to generate a monopole like this in a lab has some serious implications for physics. When Dirac first hypothesized the monopole in 1931, he realized that the existence of such a thing in nature would confirm a fundamental idea in modern physics — the quantum nature of electricity. This means that electric charge can only exist as whole number multiples of some fundamental basic charge — you can't have something with one half the electric charge of an electron.

Various theories of the Big Bang suggest that in the unfathomably high temperatures of the very early universe, exotic magnetic monopole particles should have formed. Some of these particles should still exist today, although they would likely be extremely rare. Finding a natural monopole would help us better understand the conditions of the newborn universe.

Scientists have searched for evidence of these naturally occurring monopoles in places ranging from Antarctic ice to lunar rocks. To date, these hunts for naturally occurring monopoles have all failed.

Making a synthetic monopole indicates that these kinds of magnetic fields can exist without violating the laws of physics, leaving open the door for a natural monopole. Future research into the properties of synthetic monopoles could lead to new insights into how to find these strange particles in nature.

SEE ALSO: A Kazakh Mathematician Claims To Have Solved An Enormously Important Equation

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What happens when you pour beer into a hot frying pan?

A video that we first came across on Digg shows how the beer appears to hover over the surface of the pan, whirling around in a solid blob instead of slowly boiling and evaporating.

In physics, this phenomenon is called the "Leidenfrost effect." It can happen with any liquid, not just beer.

Normally, when you pour liquid into a hot pan, the droplets will sizzle and evaporate. But when you crank up the temperature so that the surface is significantly hotter than the liquid's boiling point, the heat is so extreme that it boils the underside of the liquid immediately. The resulting vapor acts like a bed, protecting the liquid above it from touching the hot pan. The droplets will fuse together and evaporate very slowly.

You can see the "vapor cushion" and the droplet floating above it in the diagram below:

This Leidenfrost effect is also what allows liquid nitrogen to skitter across a smooth surface:

And here's the beer again. It looks really cool because of the top layer of foam: 

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A quick-hitting laser pulse has breathed new life into a multibillion-dollar effort to generate substantial amounts of fusion energy.

The 192 laser beams at the $3.5 billion National Ignition Facility have now triggered fusion reactions that briefly sustain themselves.

The reactions, reported February 12 in Nature, produced nearly 10 times as much energy as the previous record for laser fusion research. But they still fall well short of recouping the energy supplied by the world's most powerful laser.

"It's a very important milestone," says Steven Rose, a plasma physicist at Imperial College London. "However, there are many other milestones to pass."

In 2009, NIF officials at Lawrence Livermore National Laboratory in California were a far more confident bunch. Computer simulations had suggested that a NIF laser pulse could compress a layer of frozen hydrogen within a peppercorn-sized plastic capsule to one thirty-fifth of its original size. The extreme pressure would drive up the temperature to 50 million degrees Celsius, causing pairs of hydrogen nuclei to fuse and cumulatively release more energy than the lasers supplied.

Had NIF achieved that milestone, known as ignition, it would have marked the first time a controlled fusion reaction generated more energy than it took to get started. "A lot of people thought this would be a walk in the park," says Robert McCrory, the director of the University of Rochester's Laboratory for Laser Energetics and a frequent NIF collaborator.

But NIF hasn't come close. For reasons unknown, the fuel resists compression, often warping into bulbous shapes and tearing apart before much fusion takes place (SN: 4/20/13, p. 26). "Mother Nature doesn't like putting a lot of energy into small volumes," says Livermore physicist Omar Hurricane. "So she fights you on it."

In May 2013, physicists fought back against nature by changing the timing of the laser pulse. Instead of ramping up the laser energy gradually in an attempt to achieve maximum compression, the researchers tried delivering an initial surge of high energy to swiftly drive the fuel inward symmetrically before it could tear apart. Initial experiments showed promise that this so-called high-foot laser pulse could overcome some of NIF's problems.

Excitement peaked on September 27, when researchers fired a high-foot laser pulse with 1.8 million joules of energy at a small gold cylinder called a hohlraum that held the plastic capsule. More than 99 percent of that energy was lost as it cascaded from laser to hohlraum to the fuel inside the capsule. Nonetheless, an 11,000-joule infusion was enough to implode the fuel and spark a flurry of fusion reactions, transforming pairs of hydrogen nuclei into energetic neutrons and fast-moving helium nuclei. The newly formed helium then crashed into more hydrogen nuclei, transferring heat and spurring more fusion reactions.

During the 160 trillionths of a second of sufficient pressure and temperature, about 5,100 trillion fusion reactions took place. The reactions produced 14,000 joules — more energy than the fuel absorbed. That's a first for any laser fusion experiment. However, it's well short of compensating for the 1.8 million joules from the laser. It's analogous to making a solid return in the stock market, but only after the broker took a commission of more than 99 percent of the initial investment. "It sounds very modest and it is, but it's closer than anyone has gotten before," Hurricane says. "That's a major turning point in a lot of our minds."

Much of Hurricane's optimism stems from the fact that about half the 14,000 joules produced resulted from helium nuclei heating the fuel from within. NIF won't achieve ignition, McCrory says, unless helium fosters a chain reaction that exponentially increases the fusion rate. A recent experiment, conducted too late to appear in the Nature paper, produced nearly 10,000 trillion fusion reactions — a target figure the NIF-overseeing Department of Energy has aimed for — that resulted largely because of self-heating.

The high-foot laser experiments also mark the first time that real-world results largely matched the predictions of computer simulations. Rose says that physicists are no longer working blind when considering new ideas to push closer to ignition. "If you ever want to make any progress, you're going to have to do that with the aid of simulations you believe," he says. Rose thinks physicists finally have that confidence.

To make progress, physicists have to slash the 99 percent commission so that the fuel absorbs more of the laser energy, as well as increase the return on investment by coaxing more self-heating. Researchers have a bunch of ideas to test in simulations and experiments, including changing the shape of the hohlraum, replacing plastic capsules with ones made from diamond and further tweaking the timing of the laser pulse.

McCrory warns that NIF is still a long way from ignition. But after more than four years of frustration, Hurricane and his colleagues finally feel like they're on their way. "A lot of people are jazzed," he says.

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BI Answers: Why do curlers sweep the ice?

Curling is one of the more unusual sports of the Winter Olympic, often drawing comparisons to shuffleboard, but played on ice.

A roughly 42-pound curling rock, or stone, is pushed then slides down a sheet of ice, while two players furiously sweep the surface in front of the stone. The sweeping motion heats up the ice, causing it to become slick, which reduces friction between the stone and the ice. The stone travels farther and straighter as a result. The goal is to get the stone closest to the target, called a "house."

Points are scored based on distance from the house, and at the end of the game, the team with the most points wins.

Mark Shegelski, a professor of physics at the University of Northern British Columbia, who has also published several scientific papers on the physics of curling, helps us to break down the science of the game.

A game of friction

Friction (or a lack of friction) is what influences the motion of the curling rock. Friction is a force that's created when two surfaces move across each other (in this case the stone and the ice) and it always opposes the directional motion of the moving surface (in this case the rock).

Friction is also dependent on the texture of both surfaces. The ice is slippery, but it still has friction that acts to slow the rock down. As the rock slows down, it gets deflected, or curls, in one direction. If the rock is rotating counter-clockwise, it will curl to the left. If it is rotating clockwise, it will curl to the right.

The direction of the curl is the result of a number of things at play. Take a rock that is rotating counter-clockwise. At the front half of the stone, the direction of motion is to the left and the opposing force of friction is to the right. At the back half, the direction of motion is to the right, so the opposing force of friction is to the left. Importantly, the amount of friction at the front and back are not equal. That's because the curling stone has a tendency to tip forward as it slides down the ice. The leading half pushes down harder on the ice than the back, generating more friction at the front. If the same experiment was performed using an upside-down cup on a table, the cup would spin right because the force of friction at the back (where the sideways motion is to the right) is less than the force of friction at the front (where the sideways motion is to the left).

But the opposite happens in curling due to another phenomenon. Shegelski believes that the high pressure warms the ice more in the front, which creates a very thin, liquid film. The melted ice acts as a lubricant to reduce the force of friction at the front of the rock. The friction at the front of the stone, which is exerted to the right, is now less than the friction at the back, which is to left, so the rock curls left.

The ice and rock

Curling is not played on smooth ice used for sports like bobsledding or skating. Instead the surface has little bumps, called "pebbled" ice, made by spraying tiny droplets of water on the ice that freeze. "It's like a whole bunch of mounds and a lot of valleys in between," Shegelski said. The curl is too much on smooth ice, making it hard to herd the stone toward the target. Pebbled ice is used because it makes the spin controllable, according to Shegelski.

In addition, the curling rock is made from a rare granite that repels water well. This "waterproof" property keeps the rock, which is slightly hallowed out on the underside, from suctioning to the surface of ice and getting stuck.

The purpose of sweeping

In the game of curling, sweeping is critical. It's what changes the path of stone after it's thrown down the ice. Sweeping works by warming up the ice and reducing friction, which makes the rock curl less and therefore move straighter, says Shegelski.

Vigorously sweeping the ice in front of the rock makes it travel a few meters farther than if the stone had continued without interference.

"If a rock is shot too fast, the sweepers can't do anything. But if it's light, they can bring it where they want," said Shegelski.

Sweeping also acts to clean the ice of little bits of dirt and debris that can build-up over the course of the game and catch the rock.

Although shooting the rock isn't too physically demanding, sweeping requires athletes to be in good condition. The sweeper applies a lot of pressure to the ice simply by pushing his or her weight down on the broom. But "to move the brush side to side, rapidly and with high pressure," says Shegelski, "you need arm, back, and other torso muscles."

This post is part of a continuing series that answers all of your "why" questions related to science. Have your own question? Email dspector@buisnessinsider with the subject line "Q&A"; tweet @BI_Science; or post your question to our Facebook page.

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It practically feels like Summer in Sochi, but the Olympic games must go on.

So, how do they make it feel more wintry (and actually ski-able) out on the slopes? By making their own snow. And the process is more complicated than you might think.

No two snowflakes are alike. In nature, the unique shapes are the direct result of the process that happens in the clouds as these flakes are built, before they fall to the ground.

The process starts with a speck of dust or dirt in the air, which acts as a surface for the molecules of water that form clouds to condense into ice crystals. These ice crystals are the perfect spot for more water to freeze into ice crystals and so on until the snowflake is heavy enough to escape the cloud.

Recreating that process here on Earth, to make artificial snow, is difficult.

To do it on the slopes, big snow-making machines spray super-cooled water and tiny particles for the water to freeze onto high into the air — about 20 to 30 feet. This is so the spray can freeze the way it does in the clouds.

But because these flakes aren't created in real water clouds, the ice crystals forming the artificial snow make their way down to Earth much quicker, before they really form big fluffy flakes. Man-made snow is fifty times harder and four times denser than natural snow. 

There are even environmental consequences of this snow-making procedure, since typically, low snowfall happens during drought conditions. Using extra water swept up from an already dry area has negative effects on the plant and animal life, as well as local water reserves used for drinking water.

Covering a mountain in snow takes a lot of water, as much as a city of 50,000 people. In Sochi this season, they've made enough snow to cover about 500 football fields to a depth of two feet, according to the New York Times. The machines also use a ton of power and their pumps are often run by polluting diesel engines.

The video, uploaded to YouTube by the American Chemical Society, describes the essentials — everything from temperature, humidity, and even added bacteria:

There's also a New York Times article about how they are making snow in Sochi specifically >

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