Two bubbles merge in an arrangement which minimises the total surface area, given the air stored in each compartment is equal to the original air in each bubble. [A single bubble is a sphere, which is the minimum surface are for a given volume.] The two compartments are parts of spheres, and the boundary between them is part of another sphere meeting the other walls at 120 degree angles. If the two bubbles were originally the same size, the boundary sphere has an infinite radius, giving a flat wall. Though it is a familiar picture to anyone who has blown bubbles, it was only proven that this was how double bubbles are made in 2002. [more1] [more2] [code]
Metal-loving researchers analyzed the collective movement of individuals in mosh pits, which could help explain mass movements in other extreme situations.
The algorithm that won an Oscar
Hollywood likes a good explosion. Now, with the help of an open source algorithm called Wavelet Turbulence, filmmakers can digitally create pyrotechnics that were formerly time-consuming and difficult to control.
UCSB’s Theodore Kim (along with three collaborators) picked up the Academy Award in Technical Achievement for Wavelet Turbulence. The algorithm uses a theory of turbulence developed in the 1940s by Russian mathematician Andrey Kolmogorov.
So far, it has been used in over 26 major hollywood productions including Avatar, Sherlock Holmes, Hugo, and Super 8 (pictured above).
Physicists Discover 13 New Solutions to Three-Body Problem
It’s the sort of abstract puzzle that keeps a scientist awake at night: Can you predict how three objects will orbit each other in a repeating pattern? In the 300 years since this “three-body problem” was first recognized, just three families of solutions have been found. Now, two physicists have discovered 13 new families. It’s quite a feat in mathematical physics, and it could conceivably help astrophysicists understand new planetary systems.
Something from Nothing? A Vacuum Can Yield Flashes of Light
“Virtual particles” can become real photons—under the right conditions.
A vacuum might seem like empty space, but scientists have discovered a new way to seemingly get something from that nothingness, such as light. And the finding could ultimately help scientists build incredibly powerful quantum computers or shed light on the earliest moments in the universe’s history.
Quantum physics explains that there are limits to how precisely one can know the properties of the most basic units of matter—for instance, one can never absolutely know a particle’s position and momentum at the same time. One bizarre consequence of this uncertainty is that a vacuum is never completely empty, but instead buzzes with so-called “virtual particles” that constantly wink into and out of existence.
Polymer Grabs Energy from Water
MIT engineers have created a new polymer film that can generate electricity by drawing on a ubiquitous source: water vapor. The new material changes its shape after absorbing tiny amounts of evaporated water, allowing it to repeatedly curl up and down. Harnessing this continuous motion could drive robotic limbs or generate enough electricity to power micro- and nanoelectronic devices, such as environmental sensors.
“With a sensor powered by a battery, you have to replace it periodically. If you have this device, you can harvest energy from the environment so you don’t have to replace it very often,” says Mingming Ma, a postdoc at MIT’s David H. Koch Institute for Integrative Cancer Research and lead author of a paper describing the new material in Science.
Read more: http://www.laboratoryequipment.com/videos/2013/01/polymer-grabs-energy-water
Your daily “wow” video.
This latest video, Ferienne, uses more of those ferrofluids, taken to another level of visual complexity (and a pretty nice beat to boot). The shapes you see here are like peering into the invisible, using the ferrofluids to reveal the shapes of unseen magnetic fields. These are forms that we could never create in any other way, and are so random that each one may never be seen again.
Previously: At this rate ferrofluids are going to become my favorite thing on the internet. Don’t miss these dancing spires of “liquid wow” from a few weeks ago (plus more on the science of ferrofluids).
(by Afiq Omar)
This is obscenely cool.
Researchers know why ribbons and hairs curl, but few have examined the dynamics of an object going from straight to curled up. A study in Physical Review Letters looks at the simple case of a curved metal strip that is straightened and then released. Using a combination of experiments, numerical simulations, and mathematical analysis, the research team has performed a complete study on the shape and speed of the strip as it curls. The work provides a basic framework for explaining curling in future micromachines or in the splitting open of a red blood cell.
Image by P.-T. Brun & B. Audoly/CNRS
A pinhole camera created from an egg. Pinhole cameras are often used in introductory physics courses to illustrate the principles of optics. The following was taken from a lab exercise at Rice Univerity:
A pinhole camera consists of a darkened box or room with a small hole at one end. Because light travels in straight lines, the hole permits rays from each point of an object to fall only within a small circle on the opposite wall, effectively forming an image. As the pinhole is made smaller the image will become more distinct until the hole is so small that diffraction becomes important.
Although pinhole cameras were probably known to the ancient Greeks, they are still used in preference to lens systems in some situations. Pinholes are obviously useful for imaging x- rays or particle streams, where no lens materials are available, but even for light they offer complete freedom from linear distortion, virtually infinite depth of focus and a very wide angular field. Modest resolution and a very dim image are the disadvantages. Overall, pinhole cameras are worth study because they are useful and also because they illustrate some interesting physics.
In 1916, Albert Einstein revolutionized the physics world with his theory of general relativity. This theory was the first to predict the existence of gravitational waves - a fascinating concept. Gravitational waves are effectively ripples in the curvature of spacetime which travel outward from the source - sources could possibly include binary star systems composed of white dwarfs, neutron stars or black holes. Gravitational waves cannot exist in the Newtonian theory of gravitation, since in it physical interactions propagate at infinite speed.
Einstein’s theory of general relativity effectively states that gravity is a phenomenon due to the curvature of spacetime. Massive objects cause this curvature - with mass being roughly proportional to the strength of the curvature that object produces. As massive objects move around in spacetime, this curvature inevitably changes. In general, gravitational waves are produced by objects whose motion include acceleration and are not symmetric (examples of symmetrical motion would be an expanding balloon or spinning cylinder). When accelerated, these objects would cause disturbances in spacetime which would spread like ripples on the surface of a pond. This disturbance is known as gravitational radiation - which is thought to travel at the speed of light and never stop or slow down, yet weaken with distance.
Although gravitational radiation has not been directly detected, there is indirect evidence for its existence. The 1993 Nobel Prize in Physics was awarded for measurements of the Hulse-Taylor binary system, which suggests that gravitational waves are much more than mere mathematical anomalies. gravitational wave detectors exist, yet they remain unsuccessful in detecting such phenomena.
A great introduction to 6 famous physics paradoxes narrated by David Mitchell of Peep Show.
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.