Just for fun

My friend and I just submitted a video to the Ars Technica science video contest! Anyone can submit a video with a science topic related to biology, physics, or math.

This friend from work is into photography and we have fooled around with the video on her camera for some "internal marketing videos" at the office. So...we decided, why not, let's make a science video.

Here it is: How Making Music Works

It's nothing fancy so don't expect anything. But I like the drums, piano, and glasses of water that we demo.


And now I really respect anyone that makes videos! It's hard to plan out every shot and takes teamwork. But it's also fun and this contest makes me want to try some more!

More pirate puzzles

Finally I posted the next puzzle in the pirate's adventures on an exotic island. What will the pirate do when he meets the island natives? Find out and see if you can help the pirate avoid certain death with some logic skills!
Pirate Adventures with Math (Look for puzzle no.2)

Some simple math/logic puzzles

I've been doing a couple math puzzles here and there and thought I'd add a story to these puzzles because...why not? Everything is more fun with a story!

These are some simple logic puzzles encountered by a pirate when he visits a strange and exotic island...

So far I've posted puzzle number 1! You can read it on the 'Pirate Adventures with Math' page that links to this blog.

Is coffee good for your health?

“I’m going to cut down on the coffee,” resolves a coffee drinker who may have an addiction problem. Caffeine sometimes lends coffee a negative spin. The withdrawal effects of a caffeine addiction can be pretty bad: headaches, anxiety, mood swings, and nausea. On the other hand, too much coffee at once can make you jittery and on-edge and increase your heart rate. People talk about the “post-caffeine crash". For the first couple hours you’re speeding through your work, and then the energy is gone and you want to keel over. From personal experience, drinking coffee before you sail out on a small boat will make you spew it back out again (apparently it’s from the acids in the coffee).

But many recent studies report the health benefits of coffee. According to these studies coffee may reduce the risk of type 2 diabetes, liver cirrhosis and liver cancer, Parkinson’s, and coronary heart disease to some extent or another. Other studies show that coffee can boost athletic performance and may possibly increase your lifespan. There always seems to be a new study popping up to report some health factoid like:

• Coffee drinkers with a modest intake, two to four cups per day, had a 20 percent lower risk of heart disease compared to those drinking less than two cups or more than four cups.

Okay?! So tomorrow I can wake up, drink three cups of joe, and tell myself, “This daily ritual is making me less susceptible to heart disease!”

Or can I?


A scientific study can only do so much to influence your health habits. There are reports out there saying that it takes more than 6 cups of coffee daily to get any significant health benefits. That’s good news for a heavy coffee guzzler, but 6 cups for me? No thank you. I’d be bug-eyed, anxiety-ridden, and sitting on the toilet for the better part of the day.

Sometimes those health articles have links to the original study, so I clicked on a couple links and found:

Study #1: from the Journal of the American Heart Association about “Tea and Coffee Consumption and Cardiovascular Morbidity and Mortality”

Study #2: from Hepatology about coffee consumption and the risk of liver cancer.

The strengths and limitations of a study have to be considered for it to be scientifically valid. Both studies I looked at follow a large number of participants (about 37,000 participants in one of them) for a long time (13-19 years). The studies tracked how many people got coronary heart disease (CHD) and liver cancer, respectively. The actual number of people diagnosed with CHD (1950 people) and with liver cancer (128 people) was relatively low. The number of participants and the long follow-up are good, but is 128 people big enough for a good statistic? Working with a small number of diagnosed participants could be a limitation.

Other limitations include self-reported data - people may lie about their health habits. Also, the studies attempt to adjust for other health factors like the history for a particular disease (e.g. diabetes), age, educational level, smoking and alcohol habits, weight, etc. These adjustments are made to establish that coffee consumption is the cause, not a correlation.

Interestingly, in the first study, tea and coffee drinkers were found to have opposite health habits. Tea drinkers tended to have healthier habits, whereas coffee drinkers tended to smoke and drink more, weigh more, and even had a lower educational level.

It’s also interesting to compare the health trends for the population samples of different regions. The liver cancer study focused on a Finnish population with high coffee consumption and a low risk of liver cancer. The Finnish population sample is advantageous because the variables in question are much better isolated. Previous studies with Italian and Japanese populations were obscured by higher rates of liver cancer that could be attributed to multiple factors.

These studies also lend some insight into the chemicals at work in tea and coffee. Caffeine and diterpene alcohols in coffee “could increase cardiovascular risk by increasing serum cholesterol and decreasing insulin sensitivity.” But coffee also contains chlorogenic acid with antioxidant properties that could reduce the risk of coronary heart disease. “More research necessary”, of course.

These studies offer fun facts and health bytes, but how much influence do they actually have?

When you get down to it, health advice is simple and straightforward. “Everything in moderation” is a good dose of common sense. Most articles on coffee conclude that coffee has been around for a while, and you don’t need to feel guilty about drinking it in moderation. Too much may get you wired. Too little? Well, you probably don’t need to care. Considering your own personal health background and making your own lifestyle choices speaks to common sense more than following a couple numbers and statistics.

Horse racing made easy, brought to you by your local physicist...

What is it about physicists? The other day I came across an xkcd comic that sums it all up.

Have you heard that one horse racing joke? It pretty much goes the same way. There's a breeder with a stable of race horses and he's looking for a plan to make them winners. So he asks a biologist, a chemist, and a physicist if they can come up with a solution.

The biologist says, "Yes, I can develop a breeding technique to give you the fastest and most powerful horses! In a couple of horse generations you'll have a stable full of winners."

The chemist cuts in and says, "My solution is much faster than that. I can concoct a drug for you to give to your horses. It will increase the speed of your horses by 10%, with the side effect that the lifespan of your horses will decrease by 10%."

The physicist looks up from her notebook and says, "I've got the solution! Okay, guys, let's first assume that each horse is a perfectly round sphere..."

I love those scientist/engineer/mathematician stereotype jokes. If you have a good one, send it along! :)

Ocean Waves

Waves are everywhere! They come in many different mediums and on different scales: electromagnetic waves (radio waves, visible light, Xrays), sound waves, vibrations on a guitar string and – ocean waves!

I’ve been thinking about ocean waves after I started taking a surfing class. So far, thinking about the physics of surfing has been much more pleasant than thinking about its dangers, like stepping on a sting-ray, getting hit by a surfboard, or getting pulled out to see by a rip current and drowning. These things scare me. I like to think that being scared of everything is just the tradeoff for having a vivid imagination, but anyways, I digress.

How do ocean waves work? To start a wave you need an initial energy source, and for the ocean that is the wind. A wind that blows in the same direction over a long distance at high speed can generate massive waves. The wind pulls against the surface of the water and transfers energy that builds up into waves.

They travel across the ocean and break where the ocean floor rises towards the shore. The rising ocean floor will slow down the water moving beneath the wave due to friction. The top of the wave will not slow down as much because it doesn’t come into direct contact with the ocean floor. The result is that the top of the wave travels faster than the water moving beneath it, causing the wave to rise up and curl forward. Eventually the wave becomes unstable and breaks on the shore.

*one step above a napkin doodle

This is the area where the wave smashes into you in sprays of salty sea water unless you jump the wave or ride over it on your surfboard. If you are like me this is also the area where you get stuck when you see a big wave rolling towards you and think, "I don't need to go out any further."

Actually catching a wave is much more fun than trying to get over them unscathed. They tell me that in order to do that, you have to paddle a lot! You can catch a wave when you are paddling at the same speed as the wave (you need momentum to ride a wave).

That’s a very basic overview (no Laplacians here). There is more physics involved including tides, but for now, it’s about time I posted something already!  

Report from the Festival

This past Saturday I went to Expo Day for the San Diego Science Festival. There was a big turn out for the event at Petco Park. Science organizations set up booths to share information through activities and demos, mostly geared towards kids.

I like the idea of the festival: represent science in San Diego and involve the public for free.

Most of the booths had very simple activities for the kids. That didn't stop me and my friend from participating, though (c'mon, the flier says the festival is for kids ages 3 – 93). We poked sticks through balloons without popping them, made DNA necklaces, looked at amphibians and reptiles, and solved a math problem for good measure.

The booths made a complete loop around the stadium. Because there were so many booths and people, you could only spend a short time at each one. While the festival promises to “excite your mind”, the crowds and the short activities didn't provide enough oomph to "excite my mind". Even if you gear it towards kids, you can still make something intellectually engaging for adults, too. But there was some exciting eye candy, like robots, can launchers, and plasma tubes.

Some people were great at explaining their demo to you, and others were...not so great. At science museums I always see the bicycle wheel gyroscope demo. A person stands on a turning platform and holds an upright, spinning bicycle wheel. When she tilts the wheel to the right, she and the platform turn to the right (and vice versa to the left). I had never actually done it, so I hopped on the platform and took the wheel. A couple middle school students were in charge of the demo, so I asked one of the girls why I can use the wheel to turn myself. She knew that it had something to do with spinning the wheel, but she admitted she didn't know what happens when you tilt the wheel. (What happens: conservation of angular momentum. When you tilt the wheel, you change the direction of its angular momentum. The wheel correspondingly exerts a force on you and you begin to turn in the direction that conserves angular momentum.)

If there's anything to be improved: maybe they could offer free workshops to provide something more in depth. Also, the booths were poorly organized. If they were organized by category (i.e. physics and astronomy, the environment, health, biotech...), it would be much easier to pinpoint what interests you and go there. The booths were scattered all over the place, but if they were also physically organized by category, you could find what interests you and hit up the booths that way.

That said, there was great representation and turn out. Just having all of these organizations readily available is a good start. I had a good time. This year my friend and I just volunteered at the information booth, but next year it would be fun to be at one of the actual booths interacting with everyone.

Numb3rs

Did you know that 31 million plastic bottles can be produced from 17 million barrels of oil?

Really. You don't believe me? What's that, you did the math?

Ok, you got me, I lied. If what I said was true, that would be one barrel of oil to make 2 plastic bottles. Pretty absurd, right? Actually, one barrel of oil makes 2,000 plastic bottles. That sounds better, doesn't it? What I meant to say was that 31 billion plastic bottles can be produced from 17 million barrels of oil.

That was a mistake published in the LA Times. And according to another LA Times article, "the million-billion mistake is among the most common in journalism." The article goes on to lament that the collective numeric literacy rate in America is "appallingly low".

I agree that most people do not have a good feel for numbers. Take simple quantitative estimations: how many feet is one block? How many liters of water fill up your bath tub? How tall is the tree in front of your house? In basic physics classes they try to teach you to get a feel for orders of magnitude and size. The problem is that up until taking those physics classes, I perhaps got most of my experience back in the second grade when I guessed how many jelly beans were in a jar.

There are some great visualizations of numeric quantities that I've come across. On his blog Jay Epperhart posted a cool visualization of what ONE BILLION means. And he uses the universe, with all the galaxies containing their stars and planets, to do it. Not only did I get a reference point for the number one billion, but I also got a small peek at how insignificantly small and humble Earth is. Also, xkcd has a great guide to visualizing numbers with the metric system

It's a pity that we aren't very numerically literate, because math uses numbers all the time. We're literate in English, of course, but not in the universal language that is math.

"I am convinced that the act of thinking logically cannot possibly be natural to the human mind," writes astrophysicist Neil de Grasse Tyson in his book The Sky Is Not the Limit. As math is based on the rules of logic, it is reassuring to know that for the vast majority of people, it doesn't come naturally. Like most other endeavors, it takes effort and practice to begin to appreciate the underlying beauty.

The stigma attached to math is that it is tedious and impenetrable. In his book Tyson mentions a publisher who commented that when writing a book about science, every equation included in the book will decrease the potential buyers by one half. And yes, equations are intimidating. Why make the effort if they are foreign to you?

But what if the education in America prepared us to appreciate the beauty of math, i.e. to be numerically literate? We were forced to read __________(insert tedious and boring book required for high school English) to better appreciate the English language, but we didn't get the same rigor and results to be well-versed in the language of numbers.

SD Science Festival 2010

This Saturday is Expo Day for the SD Science Festival, and I think I'm going to volunteer. I've never been to it before but it looks like fun:

The San Diego Science Festival is back! Widely known as the largest celebration of science on the West Coast, on March 20-27 the Festival is hosting dozens of countywide events promising to “excite the minds” of thousands of students and their families. As a grand finale, there will be 150+ hands on activities and stage shows at Expo Day at PETCO Park on Saturday, March 27. Check out the online calendar for complete details: http://www.sdsciencefestival.com/

How to see in 3D

I was sitting in the theater last week ready to watch my first 3D movie in the theaters, Alice in Wonderland. I looked down at my 3D glasses thinking, “Whatever happened to those red and blue glasses?” The kind you could find in a box of Captain Crunch? The glasses I was about to put on looked like geeky sunglasses. How did they work, anyway?

You might be familiar with the basics of making 3D images. It starts with how humans perceive depth.

Binocular vision

We have two eyes spaced about 5 centimeters apart to view the world at two slightly different angles. The brain processes these two perspectives and merges them into one. The brain also compares the two perspectives to calculate depth. Close your left eye and look at this WORD. Then close your right eye and look at it. The position of that word is different depending on which eye you open. The greater the difference in position, the closer the object is to you.

Stereographs

If you've played with stereographs you know how 3D images work. There are two side-by-side images, each taken from a slightly different perspective. You view the images through some kind of big goggly glasses so that your left eye only sees the left image and your right eye only sees the right image. Ta-da, the image jumps out at you!

3D Movies

Binocular vision is the idea behind filming a 3D movie. Essentially, two cameras film the same scene from slightly different angles (the two cameras are like our two eyes). 

Two projectors are used to simultaenously project the film from the two camera angles onto the screen. That's why the screen looks fuzzy when you try to watch the movie without glasses.

Here is a simplified model. Let's say we are working with light polarized at “plus angle” and light polarized at “minus angle”. 

A polarizing filter is placed in front of each of the two movie projectors. Each filter only lets light through that is polarized at a certain angle. Here is an example of a light source placed behind a polarizing filter:

Light from the Left Camera Projector is filtered through the “minus angle” polarizer. Light from the Right Camera Projector is filtered through the “plus angle” polarizer.

The light from the projectors reflects off the silver screen, retaining its original polarization.

Then the light reaches your 3D glasses.

Your glasses have two polarized lenses that filter the light so that your right eye only receives “plus angle” light and your left eye only receives “minus angle” light.

It's a fun trick to play on your brain. The brain starts to process what you see and the objects in the movie (like Johnny Depp) appear to pop out at you!

So what about those red and blue glasses? Back in the day, they filtered by color rather than polarized light. One camera angle would use red light, and the other angle would use blue light. The red and blue tinted glasses would filter the light – same concept, different method. The problem with this method is that you can't retain good color in the 3D image.

Even More

That's the basic idea of how 3D movies in the theater work. In actuality, the polarizing filtering is more complicated. If you like thinking about this sort of thing, Wired tries to explain circular polarization and how it helps you naturally move your head around and still watch a 3D movie. There's also a link to a pretty cool visualization of circular polarization.

And if you're wondering about 3D TV – yes, you do have to buy a whole new expensive TV specially designed to show 3D images (and Samsung, Sony, and Panasonic have models on their way). 3D TV uses different technology than 3D movies in the theater.

I'm looking forward to seeing how we will adapt to all of this 3D technology and how it will change the way we tell stories.

More info:
http://www.mindspring.com/~dmerriman/Imaxwrk.htm
http://science.howstuffworks.com/3-d-glasses.htm
http://masterimage3d.com/

Physics at the Olympics

Congratulations to Yu-Na Kim, who won the Olympic gold medal in ladies' figure skating last week. I could gush on and on about Yu-Na Kim and her exquisite skating. Normal people have strengths and weaknesses, and the same goes for skaters. Some skaters have great artistry but lackluster jumps, or athletic jumping but unrefined artistry. Yu-Na Kim is very rare in that all the elements of her skating are excellent. It really isn't fair. But I love watching her.

If you were watching figure skating at the Olympics last week, you were watching physics in action! There are some very simple laws of physics at work that can make or break great skating.

Take a “scratch spin”. That's one of the first real spins that a skater learns, and the technique is very simple. Despite its simplicity, it looks very cool.



See what I mean?

So how can a skater keep spinning for so long? And if you watched the video of the scratch spin, you might have noticed that the skater actually spins faster as the spin progresses. So how is she increasing her angular velocity as time passes?

Know the answer?




It's conservation of angular momentum.

Let's call angular momentum “L”. In high school physics you learn that angular momentum is the moment of inertia (I) times the angular velocity (ω).

L = Iω

You can think of the moment of inertia as the resistance of an object to rotating about its axis. If you have a cylinder or a disk or a sphere, there is a certain resistance for that object to spin.

The moment of inertia is proportional to the mass times the square of the radius:

I = MR²

The larger the radius of an object, the larger the resistance to make it spin. Try spinning two coins of equal mass on the ground. If the second coin has a larger radius than the first coin, it will be harder to make it spin as fast as the first coin. In fact, since the moment of inertia is proportional to the square of the radius, doubling the radius would quadruple the moment of inertia.

Angular velocity (ω) is the number of revolutions per second. When a skater spins, she wants to maximize her angular velocity – she wants to spin fast!

When a skater starts a scratch spin, she spreads her arms out wide and extends them to both sides. This creates a large radius from the center of her body. She also sticks her free leg out for extra radius points.

r_a is the radius resulting from the arm, and r_l is the radius resulting from the leg. Here r_a and r_l are maximum values.

Then she slowly pulls her arms towards her chest. She also brings her free leg in towards her spinning leg. This decreases her spinning radius.

r_a and r_l are decreasing, so ω increases.

As we said, the laws of physics dictate that angular momentum is conserved. This means that “L” is a fixed value. By decreasing her radius, the skater decreases her moment of inertia (I). In order for L to remain fixed, the angular velocity (ω) must increase.

Here r_a and r_l are minimum values, so ω is large.

And that's exactly what you see when you watch a skater decrease her spinning radius (and therefore her moment of inertia). The speed of the spin increases. There is no extra pushing or external forces involved – just the skater's muscles working to pull her arms and leg inward.

So the next time you watch a skater end their performance with one of those long spin combinations – okay, he's doing a camel spin, into a sit spin, into some contorted position, into a reverse sit spin, and now oh my god he's suddenly spinning so much faster it's crazy and the crowd is on its feet...!!! You can think, “oh, well that's just conservation of angular momentum”. Sweet and simple.

Thanks to Jen Leslie for the idea to write about the science behind the Olympics! Check out her blog at Scientific (mis)Communications.

More info:
Scientific American on the physics of figure skating
http://www.bsharp.org/physics/spins

Science, Media, and Improbable Research at AAAS

This year's AAAS (American Association for the Advancement of Science) Meeting just happened to be in San Diego, so I decided to attend. Luckily, the Physics Department at UCSD had slots for students to get into the meeting for free. I don't think that many of the physics students were interested in going, though, because I applied late and got a slot!

The meeting's theme was “Bridging Science and Society”. I was mostly there to bridge myself to the rest of the science community. The National Association of Science Writers (NASW) has a mentorship program that pairs beginners with veteran science reporters. Luckily again, I was able to get a great mentor through the program and shadow her for a day. She interviewed an avid science blogger who writes on A Blog Around the Clock. He explained to me that he writes about the “meta” of science communication – that is, he reports on science reporting. During his interview he talked about the dynamics of the blogosphere. I thought it was interesting when he mentioned that a NYU journalism professor likes to spend 45 minutes composing one message on Twitter. I guess the professor likes to maximize linguistic efficiency.

In general I got the sense that within science writing and reporting, some attention has been shifting towards multimedia, like video, podcasts, photos, and the hodge-podge of media you can find online. Writers don't just write anymore; they take their own videos, they tweet and facebook people, and do whatever it takes to capture our attention when we're online. This is my impression, at least.

While at the meeting I also saw an Improbable Research show. What is improbable research, you ask? It is “research that makes people laugh and then think”. These are the guys that administer the Ig Nobel Prizes. I got to the show late, just as they were finishing up with “objects found in patients' rectums”. Huh, I think they got the order right – it does make you laugh, and then think. That was followed by research linking romantic love to obsessive compulsive disorder. That was followed by the emergency bra. It's a bra that doubles as a face mask in unexpected disasters and emergencies! You take the bra cup and apply it over your face to filter out harmful dust and chemicals in the air. The emergency bra is readily available, which is great considering that almost no one in the audience had a face mask on them. Furthermore, since we have two breasts and not one, ladies, you can save yourself and the lucky man sitting next to you! The researcher also gave a demonstration. It looked pretty effective, if you ask me.

Not to end this on an absurd note... Well, actually, yes, I will, but next time I'll be sure to have some more substantial, meaty science in the works.

Tracking Our Trash, Part II

I recently got a tour of the Miramar Landfill and had the opportunity to walk on top of more than 1 million tons of trash. Granted there was a thick layer of dirt between me and the trash.

If you're curious about what a blue whale has to do with our country's solid municipal waste, you can read more about it in my article about the landfill.

And why would you or I be interested in a landfill anyway??

Well, it all starts a long time ago, in a quaint village far, far away... I read this story in school, but it resonates in light of landfills and the environment.

Tracking Our Trash, Part I

Americans are third in the world in the amount of trash generated per person. On average we generate 4.5 lbs of trash per day! In one year, one person throws away 1672 lbs of trash. Picture hauling two grand pianos out of your home – that is how much trash the average American throws away every year.

But do you ever stop to think about what happens after you take the trash out? When you throw something away – poof! – it’s as if it magically disappeared. At the end of the week the trash bin out on the curb is empty, and the cycle of refilling and emptying continues. But what happens to all those take-out containers and coffee cups we are throwing away? The story of our stuff doesn't end with a good aim and a fling of the wrist towards the nearest empty container.

Our stuff gets disposed of in four ways: recycling, composting, incineration, and landfill burying. Recycling and composting sound like the green way to go, but inevitably some waste will end up at an incineration facility or at a landfill. In 2008, 33% of America's waste was recycled, while 54% went to landfills. A landfill is like a grave for our stuff. Trash is compacted and sealed in air-tight modules and stays there, preserved, for the rest of time (well, as far as we are concerned).

This week I am exploring the Miramar Landfill in San Diego to answer the question, “What happens to our trash?” A landfill is like a time capsule, and the layers of buried trash hold stories of our cultural life. What exactly goes on at a landfill will be covered in the next post.