Thursday, November 30, 2006

Adopting Physicists and Mac & Cheese

Why did you become a physicist?

Do you enjoy mac and cheese?

How does particle physics contribute to future advances in the United States and the world as a whole?

Are you an outdoorsman?

Ever want to ask a physicist one of those questions? One of the projects I'm working on for the American Physical Society is called Adopt-a-Physicist and I thought I'd tell you a little about it today because it's just that cool! Don't worry, I'm not soliciting anything - it's a totally free project that is already underway.

This program is designed to show high school students what it's like to be a REAL physicist - by giving them a chance to interact with physicists one-on-one via online discussion forums. Participating physicists include researchers at all kinds of labs and companies, computer programmers, doctors, science writers, and many others.

Classes that participate in this program "adopt" up to three physicists (a physicist is defined as anyone with a bachelor's degree or higher in physics). Each physicist hosts a forum where he or she interacts with the students and answers any questions they have about life, careers, their field of study, etc. Hopefully they will help students realize that you don't have to have bushy white hair to be a physicist.

And the coolest thing? Anyone can read their discussion!

To browse the forums:

1. Go to the comPADRE registration form* (Digital Resources for Physics and Astronomy - don't ask me how that makes up the acronym comPADRE...) and create a login
*it's free and easy and you don't get spam

2. Go to the Adopt-a-Physicist website

3. Click on the "Log in" option at the top of the homepage (the regular login, not "student login")
and log in with your new comPADRE login

4. Click on the "Forums" option at the top of the page and choose the "Fall 2006 Physicists" forum list

5. Click on any physicist's name to view his or her discussion forum
-The most current threads in each forum are at the top, so you might start by scrolling down to the bottom when you open a new forum
-You can view a physicist's profile by clicking on his or her name once you are in the forum

PS - Gary White does enjoy mac & cheese

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Tuesday, November 28, 2006

Erasing the Day?

Sorry it's been a week since we last posted. That doesn't mean there haven't been any good physics stories or deep thoughts on physics - since we all know physicists work even on their days off - it just means we've been busy with turkey and family and Hawaii (yeah, I wish that was me).

The Palo Alto Research Center Incorporated and Xerox Research Center of Canada are working together to create erasable paper - paper that be reused many times, according to a New York Times story. Apparently office workers today use paper mainly for daily tasks, such as making notes or printing emails for quick reference, and rely on computers for long term storage.

I know that I'm constantly throwing away or recycling post-its and notebooks full of random notes that have contributed to a finished product safely stored (I hope) on a network drive. So, says Xerox, why not make paper whose ink fades in 16 hours? Then you can reuse it over and over. Not a bad idea, as long as you don't accidentally print your boarding pass on said piece of paper 17 hours before you have to board the plane. That would be bad.

The article doesn't go into much detail about the process, with the explanation consisting of "[the paper is] based on compounds that can change color when they absorb a certain wavelength of light, but can then gradually revert to their original." I need a little more than that to go on. It kind of reminds me of the secret codes we wrote when I was younger - dip a toothpick in lemon juice, write a "secret message" and hold the paper up to a lamp or under an iron to read it.

Of course the big question in all of this is - will there be a market for such technology? It is supposed to be cost-effective (Xerox plans to make the paper available for 2-3x the cost of regular non-reusable paper), but as people turn more and more to electronics to write and store their information, who knows if there will be a visible payoff for this research...

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Tuesday, November 21, 2006

Giving thanks for science

Listen to the text-to-speech Robo-Podcast.

With the thanksgiving holiday approaching, many of us will soon sit down to worship our food (note the Over the Hedge reference) with family or friends. Whether you eat turkey or have one of the non-traditional main dishes, be sure to take a moment to appreciate the science your feast represents and give thanks for the many advances in science that have led to the 20 lbs turkey and the ability to store leftover potatoes and gravy throughout the week it takes to consume them.

My favorite food at thanksgiving dinner is the heap of turkey, gravy, potatoes, and stuffing all mixed together that makes up my first course. I used to prefer apple pie over pumpkin, but pumpkin has really grown on me in my old age. Yum, I'm getting hungry thinking about it.

Anyway, imagine preparing thanksgiving dinner for all the relatives over a fire instead of a state-of-the-art Maytag or GE. Or making your pie with real pumpkins instead of the gooey mix from the local grocery store. Or even using green beans and corn straight from the garden – which you’d need to do without the modern ability to preserve them and have them available any time of year.

Thanksgiving would certainly be possible without all the modern conveniences, but it would take a lot more time to create feasts as extravagant as many of us will enjoy on Thursday. So this holiday as you think about how lucky we are to live in a free country and send a nod of thanks to the pilgrims and founding fathers, take a moment to appreciate the science that makes this day of food and football a little bit easier, and that enabled your aunt to walk again after breaking her hip, your grandpa to recover from cancer, your to sister fold laundry downstairs while listening for her baby's cry though the monitor, you to keep in touch with long distance friends, and your loved ones to come home for the holiday. And then have another piece of pumpkin pie.


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Friday, November 17, 2006

Terraced Droplets

Liquid droplets are usually rounded, as I am sure you know. But when the droplets are made of certain types of long molecules, they turn into terraced pyramids instead.

The molecules in this drop have different structures on either of their ends. The end of one molecule is attracted to only one end of a neighbor molecule, and repelled by the other. The molecules behave a little like magnets, except that it's a chemical attraction that lines them up instead of magnetic fields.

Because of the interaction between the molecules' ends, they form drops built of layers - leading to these pretty physics pictures.

The molecules in a single layer are lined up with each other, but are lined up in the opposite direction of the molecules in the layer immediately above or below.

If there is only enough material in the droplet to for a single layer, it turns into a pancake like the picture below.

I'm not sure what makes the rays that extend out all around, but it sure is cool.

In case you're wondering why you've never seen terraced drops, it's because it only happens for long molecules in very tiny drops. The drops in these images are ten or twenty millionths of a meter across. The researchers took the pictures with a high resolution atomic force microscope.

The images come from an article by Andrew B. Croll, Michael V. Massa, Mark W. Matsen, and Kari Dalnoki-Veress of McMasters University in Ontario and the University of Reading in the UK. It was published today in the journal Physical Review Letters.

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Thursday, November 16, 2006

Wireless Power

Listen to the text-to-speech Robo-Podcast


You've got a cell phone, a wireless laptop and maybe a Blackberry. You are the very picture of a wirelessly connected person on the go - until your batteries run down.

Wouldn't it be great if you could recharge all your electronics without having to plug into a charger?

A group of physicists from MIT thinks so too. They're proposing a design for a wireless power transmission system that could make power cables and battery chargers things of the past. What's more, the researchers believe the power source could run buses or possibly even nano-robots tooling around inside your body.

Marin Soljacic and his MIT colleagues presented their idea at the Industrial Physics Forum meeting going on this week in San Francisco. It created quite a stir in the press, leading to stories in major newspapers and dozens of techy websites.

The system Soljacic is proposing doesn't broadcast power the way an antenna does. Radiating energy out to space would be wasteful. Instead, a power source creates a short range oscillating electric field. Properly tuned circuits that are within range of the source suck up some of the energy. If there are no electronics to charge or power nearby, then most of the unused energy returns to the source.

As an incurable early adopter, and electronics junky, I can't wait to get the system in my house. The only problem is, I don't think it will work.

Soljacic 's idea is based on old established science, well within the grasp of nineteenth century electronics wizards like Marconi, Edison and Tesla. There's no reason that the system, if it's feasible, couldn't have been built over a hundred years ago. Soljacic has suggested that it's an idea whose time has come only with the advent of wireless communications.

But I'm not buying it. I'm sure my great grandmother would have appreciated a cordless vacuum back in 1910.

So, despite the fact that I would give my eye-teeth for wireless power, I'm not going to hold my breath.

One problem is likely to be the inefficiency of wireless power. Even Soljacic 's calculations show that the best you could get is 60% efficiency. I'd bet Tesla and Edison gave it a shot and found that it's much worse in real world conditions. Of course it might make a nice combination power source and space heater, after all the wasted energy has to go somewhere. I'm guessing it goes into heating the room.

On the other hand Soljacic may be onto something. If I'm wrong, and his wireless power works, I'll be first in line at Walmart to pick one up.

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Wednesday, November 15, 2006

Fabulous Fisics Fotos

Every year the American Association of Physics Teachers sponsors a physics photo contest for high school students. This year they partnered with Lexmark International, Inc. Here are some of my favorites...


Magnetic Distortions
I love this picture, taken by Bahoa Pan of Cranbrook Kingswood School and awarded honorable mention in the competition. The horseshoe magnet was placed on a CRT computer monitor to illustrate how a magnetic field deflects charges. Read Bahoa's description here.






Bending Water
Look closely - see the stream of water attracted to the balloon? This picture of a charged balloon attracting water molecules, taken by Matthew Claspill of Helias High School, was a second place winner. I've done this demonstration before with a charged comb and I admit that it's pretty neat, but this picture is awesome! I'm using a balloon next time.





Demonstration of Newton's 1st Law
Kevin Rosenquist of West Chicago Community High School took this first place picture. He filled a long balloon with water, set it on a railing, and punctured the balloon to demonstrate Newton's first law. The picture was taken after the balloon retracted but before the water spilled down the railing.




Coil of Smoke
This picture of a coil of smoke, also a first place winner, was taken by Marina Autina of Treasure Valley Math & Science Center. It's a beautiful picture taken to illustrate the laminar and turbulent flow of the smoke.







I've always been a fan of science and art and I think this program is a great way to let students explore science using technology and art. I'm not sure need to mention how important good communication is in science - but let me emphasize that pictures can be worth a thousand words - even in science. Sometimes more. A big congratulations to all of those that submitted pictures this year!


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Tuesday, November 14, 2006

Twining Vines

Listen to the text-to-speech Robo-Podcast

Have you ever wondered how the vines in your yard manage to work their way up a pole or a tree? The question puzzled Darwin and remained a longstanding mystery - until it was solved in a paper published in Physical Review Letters earlier this month.

The answer is summarized in the latest edition of Physical Review Focus. I have to tell you though, I have a hard time following the article in my attempt to understand exactly how the model works.

There's one thing I understand from the Focus story - the theory can tell you the largest diameter stick you should use to hold up vines in your garden. Specifically, if you measure the diameter of the curls that a vine's tendril makes when it is not wrapped around a support, then you should make sure your supports are not more than 3.3 times larger than those curls in cross section. Otherwise, your twining peas will droop and your morning glories, will lie ungloriously on the ground.

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Monday, November 13, 2006

Hot Nanotech

Toothpaste that automatically coats, protects, even rebuilds tooth enamel; nanoscopic electronics; and maybe, someday, tiny robots capable of performing minor surgical procedures within the human body . . .

These are just a few of the cool technologies that are the focus of the AIP Industrial Physics Forum meeting in San Francisco this week.

Check out Jennifer Ouellette's reporting on the meeting in the Physics Today blog.
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Saturday, November 11, 2006

Cosmological Constant Conundrum


I was browsing the online archives of physics papers today when I stumbled across an intriguing paper by Abraham Loeb of Harvard.

Loeb claims that a search for planets in dwarf galaxies could test, and possibly debunk, a common explanation for the puzzling measurement of the cosmological constant, which drives the accelerating expansion of the universe.

Einstein initially proposed the cosmological constant, as a part of his theory of general relativity, to explain why the universe appeared to be static. When Edwin Hubble showed that the universe is actually expanding, Einstein dropped the constant from his theory, calling it the greatest blunder of his career.

It turned out later that Einstein might have been on the right track for the wrong reasons. The universe is not simply expanding, but accelerating as well. As a result, physicists resurrected the constant and found that it must have a value around 0.7 to match our observations of the universe.

Although it is a tidy explanation of the universe's accelerating expansion, the observed value is problematic. Some promising theories predict that the constant should be thousands of times larger than it seems to be, while others require it to be exactly zero. None seem to predict the value we actually measure (although string theory may offer a mechanism that allows the constant to decrease as the universe goes through many Big Bang and Big Crunch cycles).

One popular, though controversial, explanation for the measured value stems from the idea our universe is only one of many in an enormous multiverse, and that the cosmological constant may take on different values in different universes. According to the anthropic argument, most values of the constant lead to sterile, lifeless universes, while only values near the one we see are conducive to life. We measure a small cosmological constant because we wouldn't be around to measure a larger one, regardless of how unlikely a small constant is among the nearly countless possible universes. It's a pat argument and difficult to argue with, considering the fact that we can't visit other universes to check it.

Loeb, however, thinks we can do the next best thing right here in our universe by looking for planets in nearby dwarf galaxies. The conditions in dwarf galaxies, when they formed in the early universe, were apparently similar to those that would exist in universes with cosmological constants thousands of times higher than ours. If we find plentiful planets in dwarf galaxies, some of which are likely to be conducive to life, then Loeb says that we can be 99.9% confident that anthropic calculations of the cosmological constant are meaningless.

Loeb points out at the end of his paper that there might be an added benefit to finding planets in old dwarf galaxies "If the anthropic argument turns out to be wrong," he writes, "and intelligent civilizations are common in nearby dwarf galaxies, then the older more advanced civilizations among them might broadcast an explanation for why the cosmological constant has its observed value."


*Personal opinion warning*

I think Loeb's paper could have profound implications for theories that predict multiple universes with random cosmological constant values. (String theory, for instance, suggests that there are as many as 10^500 possible universes - that's a ten with 500 zeroes after it - with all sorts of values for the fundamental constants).

According to multiverse theories, our universe is already unusual because the other constants (such as those controlling the strength of gravity, electromagnetic interactions, etc.) are finely tuned to support life. If life can exist in universes with high cosmological constants, then we can't use the anthropic argument to explain ours. How much more unlikely must it be, then, for us to have an unusual value for the cosmological constant? (I would say N/10^500, where N is the number of habitable universes with cosmological constant of about 0.7. I have no idea what N should be, though.)

I may be making an illogical leap here, but if it turns out that we can't make a case for an anthropically determined value for the cosmological constant, then any theory that says our constant is unlikely is equally unlikely to be true.


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Thursday, November 09, 2006

Mercury Waves Hello

Yesterday (Nov. 8), people in the Americas, Hawaii, and around the Pacific Rim set up their telescopes (with solar filters of course) and watched Mercury pass directly in front of the sun. Cool! I didn't get to see the transit, but thanks to the internet there are all sorts of great pictures available today.

In this picture (taken by Howard Eskildsen in Florida) you can see a sunspot in the upper left and the nice round shape of Mercury on the lower left. Spaceweather.com has a gallery of images that is being updated all day.

Mercury passes between the earth and the sun about 13 times a century - if you missed it this time your next chance will be May 9, 2016. Mark your calendar now!


2003 Transit of Mercury

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Tuesday, November 07, 2006

Stop Faking It! II

Earlier this year I posted about registering for a Stop Faking It! workshop. Well, last week I attended the workshop as part of the National Science Teachers Association Area Conference in the lovely city of Baltimore - it was fabulous! Actually the whole conference was. I was impressed with the variety of sessions and the quality of nearly all of the sessions that I attended.

This workshop was led by the amusing and energetic author of the Stop Faking It! materials, Bill Robertson. Bill took the 40 of us K-12 educators through force and motion concepts using the learning cycle model. We had a great time playing with chairs, ping pong balls, and balloon rockets; but the real fun was the audible "ah-ha" moments when the science behind these (sometimes commonly used) activities sunk into our brains for the first time.

Most of the sessions at the meeting were aimed at helping teachers teach science concepts to students, but Bill's workshops (and books) focus on helping teachers better understand concepts. See, he believes that teachers with a deep understanding of the science behind textbook claims will be more effective, confident teachers.

I studied physics for a long time, but this 4 hour workshop exposed the sloppy thinking that I've fallen into and my tendency to look to equations to solve problems instead of concepts. What a great reminder of why physics is so cool!

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Sunday, November 05, 2006

I Vote for Science!

The 2006 US elections are just about here, and gizmo looks almost as stressed over it as I am. Maybe we should both cut back on the coffee for a bit.

"I vote for justice!" is the battle cry of SuffraJet, a rocket propelled, equal voting rights advocate and member of the Decency Squad, from the too-short-lived cartoon The Tick. I assume everyone who goes to the polls this Tuesday is voting for justice, at least their own interpretation of it. We could argue all day over how to vote for justice, so my battle cry is "I vote for science!"

I had hoped that the newly established, nonprofit Scientists and Engineers for America (geez, don't you hate those vague "up with goodness" organization titles that seem mandatory these days) could help me by compiling information about candidate positions on science issues. But as you can see for yourself, their page listing key races is blank. So I had to figure it out all on my own.

I'm nonpartisan and registered independent, but it's pretty clear this year when you look at important science issues that a vote for science is likely to be a vote for a Democrat. In Maryland, where I live, Michael Steele(Republican) is only in support of stem cell research that doesn't destroy an embryo, while Ben Cardin(Democrat) supports stem cell research in general.

OK, it's only one issue, and the positions of the candidates are nuanced enough that voting for science in this case is not so clear. But if you look at the record of the Republican congress and administration over the past six years, a vote for the GOP is a vote against rational science. The best way I see to change course is to change congress. Although I like Steele for lots of reasons, I'm voting against him to get his party out of power. I hope the Democrats can do a better job on science in the US.

In case you're wondering which issues matter the most to me, here's a partial list.

Space-based science: We are spending WAY too much money sending humans to space as part of the administration's agenda to put people on Mars. Robotic probes do a fine job exploring space for a hundreth the cost of risking humans. The International Space Station in particular is a waste of hundreds of billions of dollars with no sign of ever giving us interesting or valuable data. Let's cancel the trip to Mars and keep sending probes into space instead.

Stem cell research: I'm for it, with as few restrictions as possible. I'm an athiest, so I'm not distracted by questions of embryo souls and such superstition. When you rely on rational thought rather than primitive mythology, it's easy to support stem cell research.

Intelligent Design: The president expressed his support of teaching "both sides" of the debate over evolution. The fact is, there is hardly another side to the debate - there's the scientifically accepted theory of natural selection, and there's (barely) a handful of intelligent design supporters who are really out to teach religion in science class. I'm pretty sure someone just caught the president off guard with the question about teaching the alternatives. But the Republican party seems more inclined than the Democrats to support the psuedoscience of creationism and intelligent design.

Education: Rewarding the best performers and punishing the under-achievers is a great way to operate a free market, but an awful and irresponsible and short-sighted way to raise our children. No Child Left Behind leaves all sorts of kids behind, if they happen to live in lower tier school districts that will lose ground every year with this policy.

I am also concerned with our current energy, environmental conservation, higher education funding, and other policies that have gone awry in the past six years.

The bottom line - I'm voting for justice (i.e. science and Democrats) this year.

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Thursday, November 02, 2006

For Once, Beryllium Outshines Diamond

Researchers from Sandia National Laboratories used the speed of sound to determine the shock melting pressure of diamond – and found it to be remarkably high. Not exactly the result researchers hoping to use diamond in inertial confinement fusion (ICF) fuel capsules were hoping to hear.

ICF is a technique that uses high-powered lasers to detonate the outer layer (called the ablator) of a small fuel capsule. This creates an inward-traveling shock wave that raises the temperature and pressure at the center of the capsule to fusion-igniting levels.


The ablator must be made of a material that can absorb the x-ray energy emitted in ICF but that also has a low atomic mass. Diamond and beryllium have been identified as prime candidates for use. Although diamond is attractive from a manufacturing and fabrication point of view, this research shows that it’s probably not the right choice for ICF applications.

The experiment showed that shock waves stronger than 10 million times atmospheric pressure are needed to completely melt diamond. Beryllium, however, needs less than 3 million times. In addition, diamond is a solid-liquid mix over a much larger range of pressures than beryllium is, placing further constraints on the design of ICF capsules made with diamond.

The researchers determined the pressure needed to melt diamond by hitting samples with aluminum/copper plates traveling at up to 54,000 mph. This created shock waves that caused a pressure wave to travel through the diamond at the speed of sound. The speed of sound is highly dependent on the phase of the diamond, so researchers were able to measure the pressures where melting started and was completed.

Recent advances in laser power and efficiency make ICF an attractive candidate for alternative energy sources. In addition, it has promising applications in defense and fundamental physics research.

You can read more about this research in the press release for the group's upcoming talk at the American Physical Society's Meeting of the Division of Plasma Physics.

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Wednesday, November 01, 2006

Physicists Reveal Fundamental Flaws in NBA's Synthetic Basketball


Synthetic NBA basketballs introduced this season — and despised by many players — are less lively, more slippery when damp, and bounce more erratically than the traditional leather balls, according to a preliminary study by University of Texas at Arlington physicists.

When Shaquille O’Neal, Kobe Bryant, Dirk Nowitzki and other superstar NBA players griped about the league’s new synthetic basketball, Mavericks owner Mark Cuban contacted James Horwitz, Chairman of the University of Texas at Arlington Department of Physics, to request a study of the properties of the new and old balls.

Horwitz responded setting up a UTA Physics investigative team, designating Professor Kaushik De as UTA Physics “MavBalls” project leader. According to the UTA physicists’ tests and preliminary results, the players’ complaints may be justified.

De, Horwitz, and their students have found:

* That the new balls bounce 5-8% less high than typical leather balls used in past seasons, when dropped from a little over four feet, requiring players to make adjustments to their shots and rebounds

* That the new balls are tackier when dry, which can improve grip, but are less absorbent. This causes the balls to become slippery when they get exposed to sweat or other moisture during a game. Such sudden changes in players’ ability to grip the ball could cause mistakes and turnovers during play. (Leather balls, on the other hand, become easier to grip when they become moist.)

* That the synthetic balls bounce 30% more erratically, leading to less predictable trajectory, which can cause problems during dribbling, rebounding and passing. The bounce is most erratic when the grooved surfaces on the ball, with the embossed Spaulding logo or NBA logos are involved.

Some of the ball’s shortcomings could potentially be corrected easily. Decreasing the depth of the ball’s embossing would reduce erratic bouncing. Over-inflating the ball to 14.5 psi, rather than the regulation 8.5 psi, is enough to get the synthetic ball to match the bounce height of a leather one. But improving grip on the synthetic compound will probably be a trickier problem. Keeping the ball dry with towels and frequently changing the game ball, as suggested by Cuban in his internet blog, Blog Maverick, may help reduce the slippery grip problem this season.

The study is a stark contrast to the assertions by Spalding, the ball’s manufacturer, that it is superior to leather basketballs. The UTA team however has not done any durability studies, which is one of the primary characteristics Spalding claims makes the synthetic ball better.

The UTA physicists point out that their current results are preliminary, and they are in the process of performing more extensive testing to definitively evaluate the controversial new basketball. Among other tests, they plan to subject the balls to aerodynamic tests in UTA's engineering department wind tunnel.

An executive summary of the study De, Horwitz and their students performed is posted on the UTA web site, as well as an article profiling the two physicists and their motivation for taking up the quest to evaluate the new NBA ball.

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