Friday, July 25, 2014

Greetings from San Diego Comic Con!

The Physics Central Team has traveled west to the Mecca of all things Nerdy: San Diego Comic Con. Here's this year's team, including this Comic Con first-timer. 
Clockwise from back left: artist David Ellis, Agent Utah, Hyperspace, Halfstache, Quantum and Spectra herself (aka Rebecca Thompson). Most of the photos in this post are courtesy of the super-equipped Quantum.
It's lovely weather here in San Diego, but we're mostly staying inside enjoying the many amazing sights of this awesome gathering. Take a look after the jump.

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Thursday, July 24, 2014

Podcast: July News Round Up

This week on the podcast, Mike Lucibella and I are bringing you some of our favorite physics news stories from July.

Some very cool technologies were announced or revealed this month. There's Vantablack, the darkest material ever invented (it absorbs all but .035% of light). It gives the impression of looking down a hole, even when it's wrapped around a 3D surface. There's also the announcement that a private company, LightSail, will test a solar sail technology in 2016. Solar sails use the physical force of photons from the sun to gain speed, the way a regular sail might use the force of wind. Solar sails have appeared in science fiction, but they could be a realistic means of getting around in our solar system without having to pack fuel for the voyage.

Scientists at the National Ignition Facility—purportedly the largest laser in the worldused their laser powers to put a bit of diamond under an incredible amount of pressure: 50 million times the Earth's atmospheric pressure (at sea level) and 14 times the pressure at the center of the Earth. Scientists believe that at the core of gas giant planets like Saturn and Jupiter, solid diamond exists under such extreme pressure. This is a very peculiar situation for any material to be in, and by studying it in a lab, scientists hope to understand a bit more about how these planets formed.

And finally, a big bit of news for the community of scientists searching for dark matter: this month the National Science Foundation and the Department of Energy announced funding for three new experiments aiming to identify dark matter. Dark matter makes up about a quarter of all the mass and energy in the universe, with regular matter (like stars, galaxies and people) making up only about 1/5 of that. Identifying the type of particle that makes up dark matter would be a major step in understanding how our universe came to be the way it is; so this is actually exciting news for more than just the dark matter scientists.

Listen to the podcast to learn more.

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Particle Dense Suspensions Lead to a Smoother Surface

Scientists at the University of Chicago have discovered a new way to create a smooth coating of a sprayed material on a surface. Using a dense suspension of particles, their technique allows for a drop to rapidly form in an even layer on a surface.

A side view of a drop impacting a glass surface, splashing, and flattening into a single layer.
Image Credit: Physical Review Letters.
In the past, viscosity and 'wettability' affected spraying a liquid (like paint) onto a smooth surface. Wettability deals with how easily the liquid spreads across a surface: a drop of water behaves differently on a piece of steel than on teflon. A liquid that's too thick doesn't spread easily, either. This new method is less susceptible to these problems.

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Monday, July 21, 2014

Physics Central at Comic-Con 2014

Once again, the Physics Central team will be attending this year's Comic-Con International in San Diego from July 23rd through July 27th.

We'll be handing out tons of free laser and Tesla comic books along with extra goodies for Comic-Con attendees.

The Physics Central team at last year's Comic-Con.

Here's what you need to know:


Booth number 2207 in the Exhibit Hall of the San Diego Convention Center.


Wednesday, July 23, 6:00 pm - 9:00 pm

Thursday, July 24, 9:30 am - 7:00 pm

Friday, July 25, 9:30 am - 7:00 pm

Saturday, July 26, 9:30 am - 7:00 pm

Sunday, July 27, 9:30 am - 5:00 pm


We'll be handing out tons of free Spectra comic books, Tesla comic books, and LED "throwies." Also, we'll be selling "Keep Calm and Fermion" shirts at the booth. Stop by, learn some physics, and take back some science souvenirs.

Our Keep and Calm and Fermion shirt will be for sale at the booth this year.

Showing off diffraction glasses LED throwies, and our SpectraSnapp app at last year's Comic-Con.

You can check out our blog post from last year to see what we got up to. And if you can't make it to this year's Comic-Con, you can read the comic books online or order hard copies from our online store.

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Friday, July 18, 2014

What Rolling Over in Your Sleep Can Say about Your Health

Whether awake or asleep, people can only lie still for so long. Staying in one position for too long can lead to bed sores as well as circulation and breathing problems. Sleeping without moving enough can also be an indication that something is medically out of order.

Various researchers have monitored turnover dynamics of sleeping people over the years, mostly by counting the number times and how far someone turns in a given period. But these two numbers are often not enough to distinguish between the sleep patterns of healthy and sick people.

A new study by a group of physicists in Japan may have found a way to glean crucial health information from the motions of sleeping people by performing a slightly more detailed analysis of their motions.

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Wednesday, July 16, 2014

Podcast: Voices of the Manhattan Project

Sixty-nine years ago today, a huge fireball rose slowly above the New Mexican desert. The Trinity test signified that for the first time, physicists working on the Manhattan Project had successfully split the atom and built the first nuclear bomb.

Photo by Jack Aeby

The Atomic Heritage Foundation's Voices of the Manhattan Project website is an unparalleled trove of historic interviews with the veterans of the project. There's collected historic recordings of everyone from the heads of the project like physicist J. Robert Oppenheimer and General Leslie Groves, to more recent interviews with the people that history often overlooks, like the secretaries, technicians and people who just lived nearby.

On this week's podcast, we spoke with the founder and lead interviewer at the foundation, and heard some of the lesser known stories of the Manhattan Project. It's an amazing peek inside America's secret cities of World War II.

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Tuesday, July 15, 2014

Bubbles Help Your Pancakes Gel

My family was big on Sunday morning breakfasts growing up, and pancakes made a frequent appearance. When I was old enough to learn how to make them, my father shared one common piece of advice: wait to flip the pancakes until bubbles start to burst on the top of the batter and hold their shape.

Image Credit: Hedvig on Flickr 
I always thought the most interesting part of this instruction was waiting for the shape to hold. That precise moment indicates the pancake is in the state of changing from a liquid to a gel, and bubbles are the best way to tell.

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Monday, July 14, 2014

The Most Highly-Cited Universities and Countries

Publish or perish.

That's the mantra many young researchers live by as they compete to establish their early scientific career. But not all publications are treated equally in the world of academia.

Some journals are considered more prestigious than others, and some papers are cited much more widely than others — a quantitative measure of a paper's influence.

And when there's a way to quantitatively evaluate a group, rankings will inevitably emerge. Each year, Thomson Reuters releases a report on the "World's Most Influential Scientific Minds" primarily based on the number and impact of a researcher's academic publications.

While the report focuses on individual researchers, the data also reveal where the highest concentrations of influential researchers work. Several big academic names make an appearance, but there's also a few surprises.

For the latest report, Thomson Reuters used data from the past 11 years to compile a list of researchers with the highest number of "hot papers" and "highly cited papers" over that period. A hot paper is defined as having more citations than 99.9 percent of all papers within its field, while "highly-cited papers" have more citations than 99.0 percent of all papers within a field.

3,200 researchers made the cut by having "the greatest number of highly-cited papers in one of 21 broad fields, 2002-2012."

By Country

The list of researchers is available online at, and you can narrow your search by the researchers' names, institutions (including locations), and fields.

USA reigns supreme with over half of the highly-cited researchers having a primary institution in the country. The United Kingdom came in second with over 300 highly-cited researchers.

The graph below charts the rest of the countries based on each researcher's primary institution.

Data courtesy of

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Friday, July 11, 2014

Impact Craters May Have Cradled Life On Early Earth

Artist's impression of a major impact event.
Fredrik via Wikimedia commons
Rights information:

Asteroid and comet impacts could have created refuges for early life on Earth, protecting the first microorganisms from the sun’s harsh rays when the planet still lacked an ozone shield.

“Most people associate impacts with the extinction of the dinosaurs, but they can also be beneficial to life,” said Gordon Osinski, a geologist at the University of Western Ontario in London, Canada.

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Wednesday, July 09, 2014

Podcast:Yoctonewtons: The Smallest Recorded Force

This week on the Physics Central Podcast, I talk with physicist Dan Stamper-Kurn about making the smallest measurement of a force ever recorded.  He and his group (including lead author Sydney Schreppler) applied a force to a cloud of 1200 atoms, using a laser. Their measurement came out to 40 yoctonewtons: that's 40 x 10-24 newtons (if you drop an apple from a third story window, it hits the ground with about 1 newton of force).

The reason this measurement is significant is because it gets to within a factor of 4 of the standard quantum limit, or SQL. This is a natural limit to how precisely scientists can measure certain variables. (The proof for this is in the Heisenberg Uncertainty Principle).  The limit arises through various means, but scientists reach it when the system itself has an uncertainty greater than the measurement. In many cases, the observer imposes this limit: for example, if a scientist uses photons to study a single atom, the photons may start to influence the motion of the atom. So at some point the scientist can't discern the natural motion of the atom from the motion imposed on it by the photons.

Reaching this limit is important for many experiments, including LIGO, the Laser Interferometer Gravitational Wave Observatory. LIGO is searching for ripples in space time, known as gravitational waves. When a gravitational wave passes by, it may stretch or contract space itself. A distance of 1 meter may suddenly be shorter by something like 10-21 meters. LIGO scientists want to measure these changes, but they are bumping up against the standard quantum limit. Nergis Mavalvala also chats on the podcast about how experiments like the one by the Stamper-Kurn group will help LIGO anticipate challenges that may arise as they approach the standard quantum limit.

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Tuesday, July 08, 2014

Expect Delays: Why Trains Slow Down When It's Hot

Last week I took an Amtrak train south for the holiday weekend, and there was a delay. The explanation: the track was under a 'heat advisory' and the train had to travel at a slower speed. This left me wondering what happened to the tracks when it got so hot outside - and why they couldn't travel at speed.

An Amtrak passenger train. Image Credit: modified from Massachusetts Office of Transportation on Flickr.
Most railroad tracks are metal and when (most) metal heats, it expands. As the temperature rises, the molecules in the metal vibrate more, and they need more 'space,' so the volume increases. Different materials expand at different rates when they're heated. That's why if you have a glass jar with a lid you can't open, you can run it under hot water. The lid will expand more than the glass - allowing you to easily open the container.

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