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.

Read the rest of the post . . .

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.

Read the rest of the post . . .

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.

Read the rest of the post . . .

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.

Read the rest of the post . . .

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

Read the rest of the post . . .

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.

Read the rest of the post . . .

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.

Read the rest of the post . . .

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.

Read the rest of the post . . .

Monday, July 07, 2014

Shockingly Smart: The Physics Behind Brain Stimulation

There's been a lot of buzz lately about a therapeutic and augmentative procedure called tDCS, with promising results. tDCS may not only aid in the treatment of conditions such as depression and anxiety, but it also may be a quick, non-invasive way to improve focus, learn skills faster, and remember facts more easily while studying.

If you're wondering why you haven't heard of this miracle technology yet, it's because of what tDCS stands for: Trans-cranial Direct Current Stimulation. In layman terms, that's "putting electrodes on your head in hopes of shocking yourself smarter". At first blush, maybe it doesn't sound so appealing, but bear with me.

Image Credit: TZA via flickr | Rights Information

Read the rest of the post . . .

Wednesday, July 02, 2014

Podcast: Dark Stars and Cosmic Cocktails

Image: Princeton Press
In Katherine Freese's new book The Cosmic Cocktail: Three Parts Dark Matter, she traces the history of dark matter and her career as an astrophysicist navigating through it.

For the last few years, she's been developing her theory of dark stars, giant primordial stars powered by dark matter annihilations, which she talks about in this week's podcast. Most recently she and her fellow researchers have been probing whether they are not only bright and gigantic, but also if they pulsate.

Certain kinds of stars, called Cepheids, expand and contract regularly in a cycle of heating and cooling. As they heat up, they expand out until they're so big they start cooling down and contracting again. On Earth it looks like they're getting brighter and dimmer over time. The length of their cycle depends on their average luminosity. Knowing their absolute brightness means that scientists can tell how far away they are by gauging how dim they appear. They're used as the standard rulers to determine how far away other galaxies are.

Read the rest of the post . . .