How To Cut a Drop of Water In HalfThis may not sound like a particularly difficult task, but a lot of science has gone in to producing an easier way of doing so. Antonio Garcia of Arizona State University has made “knives” for this task by coating zinc or polyethylene in hydrophobic chemicals such as silver nitrate and a superhydrophobic solution known as HDFT.The implications of being able to cleanly cleave a drop of water is in biomedical research where it could make separating proteins in biological fluids much easier.

How To Cut a Drop of Water In Half

This may not sound like a particularly difficult task, but a lot of science has gone in to producing an easier way of doing so. Antonio Garcia of Arizona State University has made “knives” for this task by coating zinc or polyethylene in hydrophobic chemicals such as silver nitrate and a superhydrophobic solution known as HDFT.

The implications of being able to cleanly cleave a drop of water is in biomedical research where it could make separating proteins in biological fluids much easier.

Electrons in a Magnetic FieldCharged particles in magnetic fields have a force that acts perpendicular to its motion, thus resulting in circular motion of the charge. This photo shows this in action. The purple lines show the trajectory of electrons within an applied magnetic field. The purple colour is generated by the excitation of gas within the bulb, giving rise to an ethereal, glowing hoop.Image

Electrons in a Magnetic Field

Charged particles in magnetic fields have a force that acts perpendicular to its motion, thus resulting in circular motion of the charge. This photo shows this in action. The purple lines show the trajectory of electrons within an applied magnetic field. The purple colour is generated by the excitation of gas within the bulb, giving rise to an ethereal, glowing hoop.

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DARPA’s Cheetah Bot

AGES ago I posted a bit on DARPA’s plan to create a robot emulating the movement of a cheetah, whilst ambitious, previous projects such as Big Dog (created by Boston Dynamics) have been overwhelmingly creepy and effective. Now here’s the first video of the new cheetah bot, showing it run at speeds of up to 18 mph, which although not the organic cheetah’s record of 75 mph is still pretty damn good.

Microgravity Roller CoasterPossibly one of the coolest applications of physics has to be in theme parks. Now engineers are going to try something a little more extreme than your run of the mill roller coaster. Specifically emulating zero gravity conditions while being strapped to a cart. But just to make things even more interesting they also wish to double the force of gravity in some parts of the ride. The roller coaster named "Vomit Comet" will be able to accelerate to speeds greater than 100 mph before shooting vertically upwards. At this stage the ride will slow slightly, giving its passengers the sensation of weightlessness for up to 8 seconds. The ride, designed by BRC Imagination Arts, could cost up to 60 million dollars due to the level of precision required, in fact due to the varying weight of passengers the physics of the ride will have to be recalculated every run.Image + Information

Microgravity Roller Coaster

Possibly one of the coolest applications of physics has to be in theme parks. Now engineers are going to try something a little more extreme than your run of the mill roller coaster. Specifically emulating zero gravity conditions while being strapped to a cart. But just to make things even more interesting they also wish to double the force of gravity in some parts of the ride. The roller coaster named "Vomit Comet" will be able to accelerate to speeds greater than 100 mph before shooting vertically upwards. At this stage the ride will slow slightly, giving its passengers the sensation of weightlessness for up to 8 seconds. The ride, designed by BRC Imagination Arts, could cost up to 60 million dollars due to the level of precision required, in fact due to the varying weight of passengers the physics of the ride will have to be recalculated every run.

Image + Information

oblivioncontinuum:

Superconductors.
The basic concept of a superconductor is that it is capable of sustaining an electrical current without resistance. Resistance in a circuit is what causes a loss of energy, so superconductors are the closest thing we have to perpetual motion. However, they only work at near absolute zero, or more specifically, anything colder than 91 Kelvin.
When a superconductor is cooled to these temperatures, any interaction with a magnet causes a repulsion, this effect is called the Meissner Effect. The induced field in the superconductor opposes the applied field of the magnet, therefore repelling each other. So if the two repel, how is it possible to achieve any levitation? When the magnet is moved closer the flux trapping effect is engaged and the superconductor not only repels the magnet, but attracts it as well. The magnetic flux lines from the magnet are trapped inside the superconductor causing the magnet to be held at a fixed position. This is only possible if there are imperfections in the crystalline structure of the superconductor.
Of course, the opposite effect of levitation also occurs. When the magnet is picked up, the superconductor remains in magnetic suspension, and hovers below the magnet. Another phenomena is that the levitated magnet will freely move at a fixed distance over the superconductor without friction, so the applications would benefit transport, which means we can all have hover cars now.

oblivioncontinuum:

Superconductors.

The basic concept of a superconductor is that it is capable of sustaining an electrical current without resistance. Resistance in a circuit is what causes a loss of energy, so superconductors are the closest thing we have to perpetual motion. However, they only work at near absolute zero, or more specifically, anything colder than 91 Kelvin.

When a superconductor is cooled to these temperatures, any interaction with a magnet causes a repulsion, this effect is called the Meissner Effect. The induced field in the superconductor opposes the applied field of the magnet, therefore repelling each other. So if the two repel, how is it possible to achieve any levitation? When the magnet is moved closer the flux trapping effect is engaged and the superconductor not only repels the magnet, but attracts it as well. The magnetic flux lines from the magnet are trapped inside the superconductor causing the magnet to be held at a fixed position. This is only possible if there are imperfections in the crystalline structure of the superconductor.

Of course, the opposite effect of levitation also occurs. When the magnet is picked up, the superconductor remains in magnetic suspension, and hovers below the magnet. Another phenomena is that the levitated magnet will freely move at a fixed distance over the superconductor without friction, so the applications would benefit transport, which means we can all have hover cars now.

The Theremin

Possibly one of the coolest instruments in existence, the theremin is responsible for haunting, whining music everywhere such as the original Star Trek theme. The thing that sets the theremin is apart is it that to play it, you don’t need to touch it. The theremin works by having two antennas that “sense” where the player is relative to them. One controls the volume and the other the frequency and both are modulated by the distance between the antenna and the hand of the performer. The frequency is controlled using two oscillators, one is fixed while the other is free to vary, the difference between the two frequencies is what is audible and is an example of heterodyning (combining two frequencies to create a third). The frequency of one of the oscillators can be modified because the antenna and the hand act as a simple capacitor, as the hand moves closer the capacitance increases and the frequency increases.

As a bonus fact Vladimir Lenin took lessons in playing the theremin and commissioned 600 to be built and distributed around the Soviet Union.

Video of Fragile by Sting preformed on Theremin. 

Stellar Explosions in the LabWhen an experiment consists of magnetism and plasma flying at 50 km/s you know it’s got to be good. A recent experiment conducted at Caltech involves these and more. The experiment itself was conducted to better understand coronal mass ejections which form when magnetic fields “snap” and reconnect, expelling incredibly hot plasma in the process. Another phenomenon known as a Kink instability was also present. As the plasma is essentially 20,000 Kelvin gas of charged particles (with a current of 100,000 Amps) it generates a magnetic field as it moves. This magnetic field affects the charged particles in return, causing them to spiral and cork screw, which can be seen in this picture.The Kink instability also begets another instability known as the Rayleigh-Taylor instability (which is also what causes the tendrils on the inside of the Crab Nebula) which forms when a dense fluid attempts to move through a less dense fluid, in this case the dense plasma through the lower density vacuum that trails it, causing the ripples seen.Image

Stellar Explosions in the Lab

When an experiment consists of magnetism and plasma flying at 50 km/s you know it’s got to be good. A recent experiment conducted at Caltech involves these and more.

The experiment itself was conducted to better understand coronal mass ejections which form when magnetic fields “snap” and reconnect, expelling incredibly hot plasma in the process. Another phenomenon known as a Kink instability was also present. As the plasma is essentially 20,000 Kelvin gas of charged particles (with a current of 100,000 Amps) it generates a magnetic field as it moves. This magnetic field affects the charged particles in return, causing them to spiral and cork screw, which can be seen in this picture.

The Kink instability also begets another instability known as the Rayleigh-Taylor instability (which is also what causes the tendrils on the inside of the Crab Nebula) which forms when a dense fluid attempts to move through a less dense fluid, in this case the dense plasma through the lower density vacuum that trails it, causing the ripples seen.

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Soap Films and the Minimal Surface

One subject of particular interest to me is soap films, while they hold wonder for children they’re also amazing in scientific terms. The  shape and structure of a soap films is determined by what configuration minimizes surface area, this is why bubbles are round. However other interesting shapes known as minimal surfaces arise such as the catenoid and helicoid. The catenoid is the shape formed by rotating a caternary around it’s axis of symmetry, the catenary in turn is the shape formed by a hanging chain. The helicoid is a minimal surface that can be formed from a catenoid without any deformation or stretching. Both of these shapes (along with the plane) have zero mean curvature and also minimize surface area and as such are energetically favorable shapes for soap films (with boundaries) to exist in.

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Why Do We Only See One Side of the Moon?

Every 29.5 days the moon both completes one rotation about its axis and one orbit around Earth. This may strike you as an odd coincidence or even something of a miracle. It however is neither of these, but rather an almost unavoidable consequence of gravity. When the moon was first formed it rotated much faster than it did now and was also much hotter. The thing that may not be obvious to you is that not only does the moon cause tides on Earth, but the Earth causes tides on the moon. Of course not of water, but rather of the rock itself, this means that the moon bulges like an ellipsoid both towards us and away from us. It was this bulge that robbed the moon of angular momentum by converting it into heat through friction due to the moon’s contraction and expansion. In a way it’s this same principle that may lead to liquid under the surface of Titan by creating enough friction to melt water. Over time the moon will have this same effect on the Earth and it will have a day lasting 29.5 current days, but that’s a long way off!

Images: moon’s near side, moon’s far side.

Parabolic Motion Bonus Fact!

According to relativity the parabola is the pathway that takes the mosttime. While this seems to contradict the principle of least action it needs to be stated that this is only relative to the object in motion. To a stationary observer the path is the least time taken, but to the ball in flight it takes the most time. This is because it’s a balance between the time slowing effects of increased velocity and time speeding up effect of lower gravity.

Principle of Least Action

The Principle of Least Action is a type of classical mechanics that stands separately from Newton’s laws. It also has the interesting effect of grasping a fundamental concept of the universe. Most of you will know that if left to its own devices an object or system will go towards the lowest possible energy state, a ball in mid air will fall to the ground instead of hovering awkwardly or an ice cube will melt in warm weather. What may not be so intuitive is that the same applies for time. An object in motion will take the pathway that reduces the time it takes, for example the movement of light through two mediums will occur with an angle of refraction that causes the light ray to take the shortest possible time. The concept of action is what happens when you multiply energy and time together and will always head towards being a minimum.

The interesting question that arose when the Principle of Least Action was first put forward was “how does the light know which path to take?” and this question also has an analogue in quantum physics. When a single electron is fired towards a sheet with two slits in it, we still get an interference pattern, which means that the electron is interfering with itself. The solution to this came from Paul Dirac and Richard Feynman and simply states that there is a probability that an object traveling from point A to point B takes every possible pathway. Therefore the light and electron do somewhat “know” which path to take because it some ways it could be said to have already gone through it.