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Posts tagged: physics

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UCSD Physicist Uses Math to Beat Traffic Ticket

A physicist at the Univeristy of California San Diego used his knowledge of measuring bodies in motion to show in court why he couldn’t be guilty of a ticket for failing to halt at a stop sign. The argument, a four-page paper delving into the differences between angular and linear motion, got the physicist out of a \$400 ticket.

Read his paper titled “The Proof of Innocence.”

Cheerios Effect

In fluid mechanics, the study of fluids and their reaction to forces, the Cheerios effect is the observable tendency for small floating objects to attract one another.  It is obviously named for Cheerios, the breakfast cereal - because the small o’s tend to clump together or cling to the sides of the bowl. The effect is caused by surface tension and buoyancy, and the effect also acts towards the behavior of bubbles in soft drinks to stick together.

The effect applies to any small, yet macroscopic object that floats or clings to the surface of a liquid. Some liquids, notably water, when near the side of a glass form a meniscus - a curved section of the liquid.

When these small objects are placed in the liquid, they form a dent in the formerly smooth surface. If two objects placed in the same liquid are close enough together, they will ‘fall in’ to each other because of these small dents. Additionally, objects near the edge of the bowl interact with the meniscus and curve upwards along it - appearing to cling to the side. Thus, there is no attractive force between the objects, but rather the effect is due to the geometry of the liquid surface.

Ferrofluids

Yes, this is real. Magnetism doesn’t only work on solids. A ferrofluid is a liquid that becomes strongly magnetized when exposed to a magnetic field. Ferrofluid is a portmanteau of the words ferromagnetic and fluid. The particles in such a fluid are nano-particles which are suspended by Brownian motion and typically do not settle.

Without a magnetic field, the particles within the ferrofluid are randomly dispersed and have no net magnetization. However, when exposed to a magnetic field, the particles orient themselves firmly along the field lines, and respond quickly. If the applied field is moved or removed, the particles within the ferrofluid act almost immediately.

Could giant asteroid Vesta actually be a planet?

For years, scientists have been calling Vesta an asteroid. Granted, it’s a big asteroid — at 330 miles across, it’s the second biggest in the solar system — but NASA’s Dawn spacecraft recently got its closest look at Vesta yet, and according to Dawn’s principle investigator Christopher Russel, astronomers have been finding it hard not to refer to the asteroid as a planet.

Of course, the odds of the International Astronomical Union convening to name Vesta a planet (the same way they met in 2006 to reclassify Pluto as a dwarf planet) are basically zero. So instead, astronomers have taken to describing the massive asteroid as “transitional.” But what’s with all the confusion in the first place?

Long story short: Vesta resembles a planet. And not just any planet; Vesta is home to a lot of features typically associated with terrestrial bodies like Earth. The ratio between its topography (the elevation of its various surface characteristics) relative to its radius, for instance, is more like a rocky planet’s than an asteroid’s.

It also harbors something called impact melt, the remnants of at least one collision event so powerful, it actually liquified portions of Vesta’s surface — something never observed on an asteroid before. Researchers think that this impact melt, which would have flowed readily across Vesta’s face following an extraterrestrial collision, may explain why they’ve found no evidence of volcanic activity in the form of lava flows. Scientists are convinced that Vesta’s past was characterized by long periods of volcanism, but it’s possible that any sign of volcanic activity has been hidden by collisions and impact melt.

“[It’s] because of all the impact processing over Solar System history,” explained Arizona State’s Dave Williams to BBC News. “It has destroyed all the evidence.”

The Dawn spacecraft is scheduled to continue orbiting Vesta until July of this year, when it will set a course for Ceres, the largest asteroid in the Solar System. Ceres is significantly larger than Vesta; at close to 600 miles in diameter, it actually qualifies as the smallest of the dwarf planets. It’ll be very interesting to see if its surface features are as stereotypically “planet-like” as Vesta’s.

Read more about Dawn’s latest views of giant asteroid Vesta over on BBC News.

Top image via NASA

Newton v. Leibniz - The Calculus Controversy

In Latin, the word ‘calculus’ means ‘pebble,’ meaning that small stones were used to calculate things. Calculus is essentially the study of change, and the pebbles represent small, gradual changes that can produce impressive results. The origin of calculus is not the work of a single man, not even the work of the two men pictured above - but like most major discoveries, a gradual build of overlapping discoveries, something very similar to calculus itself. The question over the creation of the branch of mathematics has become one of the fiercest rivalries in modern history - that between Isaac Newton and Gottfried Leibniz.

In 1666 (and perhaps earlier), when Newton was 23 - he had begun work on what he called “the method of fluxions and fluents,” effectively what we know as calculus. Newton’s discovery of calculus was mainly a result of practical use - he needed a method to solve problems in physics and geometry, and calculus was what resulted. On the other hand, Leibniz had become fascinated by the tangent line problem and began to study calculus around 1675.

The ideas of the two men were similar, although it is unlikely that either of them knew the specifics of the other’s work. The two men spoke in letters often, and discussed mathematics - and although the Royal Society found Leibniz effectively guilty of plagiarism later, this was not likely the case. Both men came to similar discoveries in different ways - Leibniz came to integration first, while Newton began his work with derivatives.

Although Newton discovered the principles of calculus first - he did not publish them until many years after Leibniz did. Leibniz published his first paper employing calculus in 1684, but Newton did not publish his fluxion notation form of calculus until 1693, and a complete version was not available until 1704! Nonetheless, Newton still came to the discovery first - and although both men are officially credited, Newton is the one that most people remember.

However, Newton doesn’t deserve all the credit here. The famous dy/dx notation that calculus students have come to love and hate was developed by Leibniz. Although Newton may have come to the discovery first, Leibniz attacked the problems with far better notation - and we have naturally adopted it. Instead of Leibniz’s dx/dt (shown below) notation for derivatives, Newton preferred ‘dot’ notation:

However, this dot notation can become confusing, especially when used for higher order derivatives, so it has been generally dismissed - except for hardcore Newton fanatics who insist on using his notation. Newton did not even have a standard notation for integration, but frequently switched; but Leibniz used the recognizable integration symbol:

This has developed into a fantastic controversy over the years - and has become as much of a moral question as it is scientific. Many Leibniz advocates belief that Newton doesn’t deserve full credit because he didn’t publish his findings first - while many others believe that Newton came to the discovery first, so the credit is his. Personally, I have to place myself on the side of Newton - although Leibniz’s notation is wonderful, Newton discovered the principles first.

Which side are you on?

How our universe could one day be revealed to be part of a multiverse

Right now, scientists are slowly unraveling tiny secrets of our universe that 100 years ago would have been completely unthinkable. Multiple dimensions, the fabric of time and space itself… and perhaps at some point we might be able to find some sort of evidence that our universe might be in a multiverse. Not tomorrow, but someday maybe.

WORDS: Short URL: http://tmblr.co/ZVpknxHZSea7

The Great Beards of Physics

For many Physicists throughout the ages - their beards are as remarkable as their brains. Here are just a few - from left to right:

Johannes Kepler (1571-1630): His name is synonymous with astronomy - and is best known for the eponymous planetary laws of motion that he proposed. He was a key figure of the scientific revolution, and was one of the main influences on the great Isaac Newton.

James Clerk Maxwell (1831-1879): Maxwell is responsible for formulating modern electromagnetic theory - which basically unites all of electricity, magnetism and optics. He realized that light, electricity and magnetism are all formulations of the same phenomenon. Maxwell’s scientific greatness is on par with Newton himself, but Mr. Electromagnetism’s facial hair far surpasses Newton’s.

Wilhelm Conrad Röntgen (1845-1923): He was the first to produce and detect electromagnetic radiation in the wavelength range that we know today as X-Rays. He produced the first X-Ray image of a human ever taken - one of his wife’s hand that can be seen here

Joseph Swan (1828-1914): Swan is most famous for being the first to create an incandescent light bulb - he even beat Edison to it. However, his bulbs were commercially impractical as they required large conductors to produce the necessary current.

Ludwig Boltzmann (1844-1906): Boltzmann is the man who is effectively responsible for creating Statistical Mechanics and Statistical Thermodynamics. He stated the Second Law of Thermodynamics in a statistical way, and made enormous contributions to Kinetic Theory during a time when many scientists still were skeptical to atoms. He also has what is probably the coolest grave ever.

Gersh Budker (1918-1977): This Russian Physicist is best known for his invention of electron cooling, which is a “process to shrink the size, divergence and energy spread of charged particle beams without removing particles from the beam.” However, his greatest contribution to science is obviously that incredible beard.

Inspired by this wonderful post

Mirages

When it comes down to it a mirage is essentially just an invisible mirror. Which is still pretty damn cool. Mirages are simply the distortion of objects due to “layers” of air and come in three different types: inferior (where the mirage is under the real object), superior (where the mirage is above) and Fata Morgana (which is a complex, highly distorted mirage involving multiple images). The principle behind the mirage is rather a simple one. At different elevations air has different densities, typically due to heat, which in turn causes different refractive indexes. This difference in refractive indexes causes the light to bend as it crosses from hot to cold or cold to hot air due to refraction. As such the image you see is not where it really is but is simply light from the original object being bent towards you. In the example of the highway mirage above the “pool of water” is in fact simply the reflection of the sky being “bounced” towards the observer by a hot layer of air directly above the road.

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Zero Point Energy

Everything you see around you is vibrating. The hotter it gets the more it likes to jiggle about, in fact that’s how you perceive heat, but even at colder temperatures (approaching 0 Kelvin cold) the jiggling continues. As cold as you make it, particles are still bouncing around albeit ever more slowly. This phenomenon is called Zero Point Energy and simply states that even at the lowest energy state possible a quantum system still has some degree of energy. Zero Point Energy is due to the wave like nature of all matter as of course it would be impossible to have a wave with no energy, but it also relates to the Heisenberg uncertainty principle. If we were to say that a particle (or even field) has no energy we would be defining an absolute value, which of course we cannot have. Therefore the particle oscillates around this minimum value.

Zero point energy has been confirmed experimentally by the Casimir effect. Which demonstrates that if two uncharged metal plates are put close together in a vacuum that there will be a force acting to push them together. This is because the small distance between the plates excludes vacuum energies of large wavelengths so that more energy is located outside (or inside sometimes) the plates, thus forcing them together.

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why I love energy’s relation to matter

actually matter’s relation to energy