Friday, April 17, 2015

Found Physics - Scratch Holograms

I'm always intrigued when I stumble across a cool physics phenomenon that most people would tend to pass by without a second thought. One of my favorite overlooked physics effects is scratch holograms. They can turn up just about anywhere you have a polished surface that gets scratched in patterns that are surprisingly easy to produce. In fact, most of the scratch holograms I've seen have been accidental.

While I was at the annual APS April Meeting in Baltimore last weekend, I found these patterns on just about all the tables scattered around the hotel where we were gathered to talk about black holes, gravitational waves, cosmic rays and other hardcore physics topics.

video

In the video, you can see a coin I set on the table to show you where the surface is. As I moved the camera back and forth, there appeared to be a shifting reflection. And it is indeed a type of reflection, but the pattern isn't a reflection of something above the table - it's a 3D pattern that appears to be several inches inside the table. That is, it's a hologram image encoded in the scratches on the table surface.


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Thursday, April 16, 2015

Survival Of The Shiniest: Iridescence And Defense In Nature


The color-shifting displays prevalent in nature could puzzle potential predators.

Originally published: Apr 14 2015 - 7:15pm, Inside Science News Service
By: Ker Than, Contributor

(Inside Science) — The rainbow-hued shimmer of fish scales, bird feathers, and insect bodies that change color and brightness depending on viewing angle can be mesmerizing, but biologists have long debated the purpose of the striking displays and why they are so widespread in nature.

Different organisms have evolved various mechanisms to produce iridescence, but most of them rely on light-manipulating structures. Peacocks, for example, have feathers that contain very small protein structures that break up incoming light waves and then recombine and reflect them as vibrant colors.

Image credit: By Benjamin444 (own work) | http://bit.ly/1ze70c7
Rights information: Wikimedia Commons | http://bit.ly/cEcCkh





















It's been suggested that iridescence, also called "interference coloration," plays a role in sex or species recognition. Another hypothesis is that the structures that create iridescence help repel water or reduce friction or help in regulating body temperature, and that the pretty visuals are only a side effect.

Now new research suggests there is another possibility: that for some organisms, iridescence evolved as an anti-predator defense to dazzle and confuse predators with sudden shifts in color and brightness in a bid to gain a few precious moments for escape.

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Wednesday, April 15, 2015

Podcast: The Muon Camera



Particle detectors don't always have to be massive, expensive machines at cutting edge physics laboratories. Undergraduate physics students Kristina Pritchard and Shemaiah Khopang, both at Missouri Southern State University, worked with their faculty advisor David McKee to build a muon detector out of a Sony digital camera.

Taking the camera apart. Image: Kristina Pritchard


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Tuesday, April 14, 2015

Going to Mars: How Will We Get There and Who Should Go?



Would an all-female crew make sense on a deep space journey to Mars? Would the spacecraft rotate to simulate gravity? What's being done now to prepare for such a journey?

These were some of the questions addressed last Thursday by a panel of space scientists, writers, and engineers gathered in downtown DC to talk about the challenges of going to Mars. The discussion, called Giant Leap: The Race to Mars and Back, was organized by Future Tense, a collaboration between Slate magazine, the New America Foundation, and Arizona State University.

Phil Plait of Bad Astronomy moderated the first discussion and jumped straight in by asking what it is we need to do to get to Mars.


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Friday, April 10, 2015

Physics Life Hack Number 3 - Getting Your Ride Out of a Rut, Without a Tow Truck

This Wrangler isn't stuck, because Jeeps are awesome off-road.

This is a handy trick I've had to use a few times, primarily because of my obsession with driving in places where I probably shouldn't.

Back when I had a Jeep Wrangler and a lust for exploring woodland trails and lonely beaches, I would occasionally find myself literally stuck in a rut, with no other vehicles around to help me out. Sometimes a bit of digging, a few properly place pieces of wood or rocks, or plain old pushing would be enough to free my old jalopy. When that didn't work, it was time to grab the rope and rely on physics to set myself free.


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Thursday, April 09, 2015

Beaded Chains Groove to the Music

Here are a wonderful couple of videos showing beaded chains grooving to the music.

Of course in reality the chains are being shaken by a vibrating platform, but the swirling patterns and spirals that spontaneously form lends a lovely charm to an otherwise dull set of chains. In the first video, the blue and red chains seem to be engaged in an intricate and lively dance of give and take (watch in HD for the best effect). The images taken 5 seconds apart and sped up to 10 frames per second to create the video.


These videos were created by Justin Bondy, a former master's student at the University of Toronto, and his supervisor, Stephen Morris, with the aim of studying the separation of DNA strands during cell division. They hoped the two chains would create an experimental model that could shed light on how two-dimensional polymers unmix at much smaller scales.

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Wednesday, April 08, 2015

Hollywood Earthquakes



Next month, a new disaster thriller starring Dwayne “the Rock” Johnson will hit theaters, plunging audiences into chaos and destruction following a magnitude nine earthquake on the San Andreas fault. There’s nothing wrong with encouraging earthquake preparedness, but, as the new trailers make abundantly clear, San Andreas promises to be packed with far-fetched ideas about how earthquakes (as well as tsunamis) work.

To find out what Californians should and shouldn’t be worried about — and why — we spoke with Dr. Belle Philibosian, an earthquake geologist at the Institut de Physique du Globe de Paris, who studies the seismic potential of fault systems. Philibosian has seen her fair share of Hollywood earthquake myths, starting with 1978’s Superman, in which Lex Luthor attempts to trigger the San Andreas fault with a nuclear bomb in a sinister plot to create beachfront property in the desert.


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Tuesday, April 07, 2015

Watch Cosmic Rays Live and Play 'I Spy' for Neutrinos

A recently completed neutrino detector called NOvA has an online webcam where you can watch cosmic rays collisions in near real-time. Since most of us aren't lucky enough to have a cosmic ray detector at home, this webcam is a nice reminder of just how ubiquitous these energetic particles from the cosmos really are.

Created from screenshots of the the NO╬ŻA Far Detector Event Display

 The zoo of cosmic ray particles is a whole field of study unto itself with many projects trying to determine the exact composition of particles and from where they originate. But for the physicists trying to study neutrinos these cosmic rays are all just noise.

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Monday, April 06, 2015

Research Projects Reveal How Wrinkles Form

Understanding wrinkles begins with math.


Originally published: Apr 6 2015 - 9:00am, Inside Science News Service
By: Peter Gwynne, Contributor

(Inside Science) – From raisins to fingerprints, and from tree bark to the surface of the brain, wrinkles appear throughout nature. But scientists have struggled to explain how wrinkles form.

Now two independent research teams at the Massachusetts Institute of Technology in Cambridge have developed key insights into the process.

One group has developed a mathematical theory, confirmed experimentally, that predicts how wrinkles take shape on curved surfaces. The other explains in more general terms how layered materials form different types of wrinkly patterns.

Image credit: Changyong Cao and Xuanhe Zhao

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Friday, April 03, 2015

Bicycle Safety: How does Volvo's new invisible reflective paint work?

An invisible yet highly reflective spray paint debuted in the UK a few days ago, as part of a campaign by Volvo Car to increase cycle safety. Life Paint promises to be invisible on clothes and bikes, washable and non-permanent. But the glare of a headlight will cause particles in the paint to reflect light back to the driver, making the cyclist glow.

How does this direction-dependent paint work and can it really make a cyclist safer?

Credit: Screenshot from the Volvo Car Life Paint video campaign

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