Category Archives: Science

Bristlebots being used for research at Harvard

A group of scientists and engineers at Harvard are using Bristlebots to study swarming behavior. They have published an article titled “Swarming, swirling and stasis in sequestered bristle-bots.” They have a couple of supplementary videos up on youtube as well. There’s a nice writeup of it at New Scientist, with a link to a full pdf at

Download and Print: Evil Mad Scientist Valentines

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If you’re anything like us, you’ve at some point come across supposedly-nerdy valentines and thought to yourself, “A real geek would have used an equation to express that sentiment.”  And if so, have we have got just the thing for you!

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Here’s our collection of six little valentine cards, each of which adds a little authenticity and class to the not entirely uncommon “geek” valentine genre.

Suppose that you want to communicate to your valentine just how hot you think they are. Sure, you could go with a picture of a thermometer— or a Sriracha bottle —but isn’t the thermodynamic definition of temperature itself in a whole category of its own?

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And what better way to say “I love you,” than with the gift of trigonometric identities?


Lo Res Valentines

You can download the original file here (260 kB .PDF document).

Print it out on (or otherwise affix to) card stock, and [some steps omitted] enjoy the resulting lifelong romance.

Update: The 2014 and 2015 valentines have been released!

Makerspace Launch

The Makerspace program is a joint effort by O’Reilly’s Make division and Otherlab to put dedicated space and tools for hands-on making into high schools. They describe their aims on their about page:

By creating makerspaces in an educational context, students can have access to tools and equipment that they might not have otherwise; they can collaborate on projects that are driven by their own interests, and by doing so, develop the capacity and confidence to innovate. We see making as a gateway to deeper engagement in science and engineering but also art and design.

On Monday, September 10, we’ll be attending the Makerspace launch event at the College of San Mateo. We’ll be demoing a few kits and are excited to have the opportunity to meet educators interested in bringing making into the classroom. If you’ll be attending, please stop by our table and say hi!

Curiosity on Mars!


Congratulations to Curiosity! As the New York Times says this morning,

In a flawless, triumphant technological tour de force, a plutonium-powered rover the size of a small car was lowered at the end of 25-foot-long cables from a hovering rocket stage onto Mars early on Monday morning.

A crowd of some 5000 people gathered on the plaza at NASA Ames Research Center late last night (it was only Monday Morning on the east coast) to watch presentations by mission scientists and finally the live broadcast, on the big screen.

This was a thrill.  Not only was the landing process itself incredible— watch this video, “Seven minutes of terror” if you haven’t —but it was amazing to be in a crowd of so many people excited to watch the landing as well.  Many of the people in the audience screaming and cheering had worked on various parts of the mission, including the ground-breaking (pun intended) scientific instruments aboard the rover and the new lifting-body heat shield to get it there.

Curiosity closes in on Mars

On Sunday night, the Mars Science Laboratory rover Curiosity (the one on the right; the biggest, baddest, most awesomest Mars rover ever) will attempt to land on Mars. Curiosity is a nuclear powered Mini Cooper sized robotic geologist, much bigger and more capable than previous rovers. It’s going to be a moment of great excitement when Curiosity touches down, and there are a number of ways that you can watch.

If you have the opportunity (Mars rover pun intended) check with your local science museum, planetarium or hackerspace to find out if they’re hosting a viewing party.

Curiosity model at Exploratorium

Here in California, the Exploratorium currently hasa special exhibition up, including the simplified full-scale model of the rover in the picture above. They will be airing a live webcast of the landing on Sunday night.  And, NASA Ames Exploration Center in Mountain View, is hosting a live broadcast on-site with over 5000 people. The free tickets for the event went very quickly.

And, if you can only watch on the internet, NASA TV is NASA’s official video channel.  Star Talk Radio has a list of places to watch online. Space Industry News has a similar lineup, which includes a link to a google map of events.

Viewing the Transit of Venus

Transit of Venus with binoculars

Venus is just now passing between the earth and the sun, and so we stepped outside to take a look. We brought out a pair of binoculars to use to project the image of the sun onto a piece of paper on the ground. We also took a solar viewing film, but it turns out that the binoculars were a great way to see it as a group. These pictures were taken just after Venus crossed over the edge, and the speck you can see at the edge is much clearer if you click through to the large size on flickr. Over there, you may also be able to make out a couple of sunspots that we were also able to see with the binoculars, but not with the viewing film. Remember, don’t look directly at the sun without proper safety equipment! (See our earlier post for more details on viewing techniques.) The transit is still underway, so you still have a chance to get outside and see it!

Transit of Venus Closeup


Update:  Part II, with a slightly different method.

Venus Transit 3

To get a slightly better view, we used a simple telescope mounted to a tripod.

Aside: This is the Galileoscope, a high-quality, very low cost telescope for $50 (or as little $25 in classroom packs).  It’s designed to let you discover everything that Galileo could see with his telescope, including craters on the moon and the moons of Jupiter, albeit with modern optics that dramatically improve image clarity.


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Now, the one thing that you really don’t want to do with a telescope is directly look at the sun through it. (It’s bad enough to stare into the sun; it’s much worse to concentrate the light into a tiny spot.  That’s a good way to start fires, not view the Transit!)

What you can do is to project the light from the telescope onto a piece of paper or matte-white plastic. Adjust the focus until the edges are sharp and— poof! —suddenly, you can see the sunspots.

Venus Transit 1

And the image quality isn’t half bad.  This picture was taken right at the “peak” of the Transit, when Venus was as far into the disk of the sun as it went.  Our image on the screen is about two inches (five cm) across, and it’s easy to make out the features.

Most stunning of all is the incredibly rare opportunity to see a planet in the sky not just as a “point of light” but to see it for what it is: another planet just like ours, slowly orbiting around the same sun.

A Spectacular Speck on the Sun

Today, Tuesday June 5, 2012, the planet Venus— the planet in our solar system that is closest to the shape and size of Earth —will leisurely pass squarely between the Earth and sun.

The Transit of Venus, as it is called, is a once (or maybe twice) in a lifetime event. If at all possible, make an effort to see it today, because you won’t have another chance… at least until the year 2117.

While it will not be visible everywhere in the world (see map), it will be visible for all of North America, Asia, Australia, and eastern Europe. (The latter, towards sunrise on June 6.)   The transit begins at 22:09 UTC, peaks at 01:29 UTC, and ends at 04:49 UTC.  Here in the PDT time zone, that’s 3 PM, peaking at 6:30 PM, and finishing below the horizon. (More at the LA Times.)

Now, how to actually view it?

If you were clever, you might have stashed away an eclipse-viewing filter from the recent solar eclipse.  If not, another option— one that is cheap and easy to find at hardware stores —is a set of welding glasses with a #14 filter. (That’s black glass. Sadly, those dark green goggles that you found in the shed are likely not safe for direct solar viewing.)

But, as the Ontario Science Center warns you,

Be careful: there are many materials that may seem to block out the Sun’s rays, but which are not safe to use for solar viewing. DO NOT LOOK AT THE SUN THROUGH sunglasses, photographic neutral density filters, polarizing filters, photographic film, dark plastic such as garbage bags, or smoked glass.


The other approach to consider is indirect viewing. You can build a pinhole projector, or a simpler yet version.  You can also use a telescope set of binoculars to focus sunlight onto a surface for indirect viewing. (Using binoculars or a telescope for direct viewing requires a carefully chosen solar filter, to be safe.)

If all else fails— maybe you’re in cloudy Portland —NASA has got you covered. Head right over here for a “live” feed of solar pictures from the SDO spacecraft in orbit around the Earth, and updating every 15 minutes.

Update: A nice summary of the historical background of viewing transits of Venus is here.

[Image source]

Shadows of an Eclipse

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There were a lot of amazing things that we saw this weekend at Maker Faire— everything from live demonstrations of snails creating artwork (by Presley Martin) to the DIY pick and place machine (from

There was also something special in the sky: the solar eclipse on Sunday.

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Viewed elsewhere (e.g., further north in California) this was an annular eclipse, where the sun does not disappear entirely, but instead becomes a ring of fire (since the apparent size of the moon is not large enough to block the full disk of the sun).

For us at Maker Faire in San Mateo, it was a spectacular partial eclipse, which we were able to view through solar viewing filters, kindly handed out by the Exploratorium.

Eclipse 2012- 8

Of course, it turns out that you don’t actually need a solar filter to watch the eclipse. Any little aperture— in this case the cap between my hand and the camera —can act as the pinhole in a pinhole camera and project the image of the sun onto a surface.

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Eclipse 2012- 2

So if you’re not sure if an eclipse has started, or how much of an eclipse it is, just hold out your hands and make some little apertures; the shadows will show up with little bright spots in the shape of the sun, whether that’s a circle, ring, or crescent.

Eclipse 2012- 1

Stranger yet is to look around at all the shadows that you see every day. Even the shadow of your hand takes on an unexpected shape when the sun is anything other than round.
There are actually five outstreched fingers on my hand here, but you can hardly tell that when every bit of light that seeps through (or around the edges) projects a crescent-shaped image.

We take for granted that the shadow of an object will the same shape as the object, but as you can see, that isn’t necessarily the case when the light source isn’t round.

Urban scientist: An unusual spider

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It’s always good to keep your eyes open, ready to see new things. I came across this striking not-particularly-small spider with a bright red velvety abdomen, just hanging out on the concrete side of a building here in Sunnyvale, California.

I’ve never seen one of these before! How might you go about identifying it?

Continue reading Urban scientist: An unusual spider

A stunning display of natural birefringence

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In a recent visit to the Penn Museum— the University of Pennsylvania Museum of Archaeology and Anthropology –we came across a most unusual artifact in their Chinese Rotunda: a giant crystal ball:

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For a higher-quality image– without the display case– take a look here.

Here is what the display placard has to say:

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Crystal Sphere
Rock crystal, Silver Stand
Qing Dynasty (1644-1911 CE)

An ornamental treasure of the Imperial palace in Beijing, the crystal sphere was said to have been a favorite possession of the Empress Dowager Cixi (1836 -1908 CE), under whose watch imperial China crumbled. The rock crystal originated in Burma and was shaped into a sphere though years of constant rotation in a semi-cylindrical container filled with emery, garnet powder, and water. The forty-nine pound flawless crystal sphere is believed to be the second largest in the world. The stand in the shape of a wave was designed by a Japanese artisan.

So, not only is it a giant crystal ball, but it’s a historically interesting giant crystal ball. But besides that– and its brief modern stint as a hat rack –what’s genuinely remarkable about this particular artifact is that it’s made from a chunk of rock crystal, better known as quartz crystal.

Now, those “crystal balls” that run-of-the-mill fortune tellers use are often just glass— glorified playground marbles or perhaps so-called lead crystal, which is actually just another type of glass.

Quartz crystal, on the other hand, has a structured atomic lattice that leads to some very interesting physical properties including piezoelectricity, triboluminescence, and birefringence. These properties arise from the crystal structure itself; they are typically minimal or absent in glasses such as fused silica (glass made by melting quartz crystal).

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While the museum probably wouldn’t want you compressing or grinding their crystal ball for piezoelectricity or triboluminescence experiments, the birefringence is boldly sitting out on display.

Let’s look a little closer:

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The sign, across the room reading “TEXTILES” is not just inverted like it would be with a spherical lens, but also– plain as day –appears as double image, even through our single camera lens.

Why? Quartz crystal is a birefringent material, which means that light rays entering the material experience two different indices of refraction, depending on their polarization and orientation with respect to the crystal lattice. In practice, our eyes see all polarizations, so this means that the crystal ball acts like a superposition of two glass balls with different indices of refraction– and light rays entering the sphere at any given point can follow two different paths to reach your eyes. Hence the double image.

It’s also worth noting that the two separate images are composed of photons with perpendicular polarization. If you were to look at this sphere through a linear polarizer (e.g., one lens of the 3D glasses that they use in modern movie theaters), you could turn it such that only one of the two images was visible at a time.

Birefringence is not particularly rare, and there are materials (like certain forms of calcite) that have huge, easily visible birefringence. Optical devices made from flawless natural calcite, exploiting this property, are tremendously important to scientific research and industry.

We tend to think of a quartz crystal as being perfectly clear– not something that gives you a double image when you look through it. That’s because quartz is only very weakly birefringent, especially when compared to calcite. Quartz is, however, still extensively used in industry in applications for which high transparency and very slight birefringence are key, such as optical wave plates. And, what’s truly remarkable about the Penn Museum sphere is that this tiny property– usually so hard to see –is so plainly visible to the human eye.

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Finally, as we mentioned, the amount of birefringence depends on the orientation of light rays with respect to the crystal itself.

This means that if we walk one quarter circle around the sphere to a point where we’re closer to looking directly along (or perhaps, perpendicular to) the optical axis of the quartz sphere, the image suddenly becomes (if you’ll pardon the pun) crystal clear.