Happy World Bicycle Day!

Apparently today is World Bicycle Day! [1]

Coincidentally (i.e., before I learned this fact), this morning I happened to rediscover the presentation I put together to kick off the discussion at a virtual SciFoo session that I proposed and MCed back in 2021, entitled, “Creating the (next) bike revolution: biking as a powerful tool for improving health, climate, society . . .”

Therefore, in honor of World Bicycle Day [1], I will reiterate here the three claims I made there — which were then supported rather than refuted over the course of said session, and which I still stand by today:

Claim 1: Bicycles are the ideal choice for trips of a couple miles
Claim 2: More biking is better for us, both individually and collectively
Claim 3: Bike infrastructure is a powerful tool for social/societal good

title slide with three claims, plus photos of a fold-up bike, bike-based mail delivery, and a bunch little bikes parked at a preschool

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An element(ary) building block analysis

Scientists are often known for our tendency to let our professional lives intermingle with our home/family lives. One classic portrayal of this in fiction is Dr. Murray (the mother of the main character in Madeleine L’Engle’s A Wrinkle in Time), a microbiologist who is not yet done with her experiment when it’s time to start dinner . . . so she just cooks the stew on a bunsen burner in her home laboratory. (When I first read the book, many years ago, this struck me as a eminently reasonable approach, and it did not cross my mind for an instant that there might be any potential downside to this arrangement — e.g., worries about the stew contaminating her experiment, or vice versa.)

Dr. Murray’s kids were already school-aged, though. When your child is a baby, and you are spending time at home with it, there’s decent likelihood that — amidst all the feeding, soothing, diaper-changing, general mess-management, etc. — you will not have sufficient resources (time, energy, and/or access to antimatter or high-voltage power supplies) to make much progress on your real research projects. Thus, you might instead find yourself re-directing your “usual methods” to your current situation.

This might mean recording every time the baby is asleep, for an entire year, and then producing a plot of the data (broken down into 15-minute increments) that nicely illustrates how your newborn’s many shorter naps gradually coalesced into fewer, longer periods. Or it might mean meticulously charting breast-milk production, so as to test the frustrating and often contradictory claims that various experts have made to you about this process. Perhaps you merely ponder whether the not-quite-yet-fussing baby’s gradual motion/rotation on the floor can be well described by a random walk model. Or maybe you find yourself analyzing the color choices on your child’s wooden blocks that are decorated with the elements of the periodic table:

When you see this, what question(s) spring to mind?

I personally didn’t do all of those when I was home with my baby — just most of them. And although the baby in question is now 4.5 years old (but still loathe to let me focus my attention on complex physics questions in her presence), I recently found out that 2019 is the International Year of the Periodic Table of Chemical Elements, so I figured it was a good opportunity to dig out some of those old results. Continue reading

Turning through the years

A new year usually means it’s time for a new calendar. One can opt for 12 months of natural parks or scenes from a favorite film or TV show, 365 days of political cartoons or origami projects, or so many others. The possibilities are nigh endless.

But what if you really liked last year’s calendar? Maybe it already had the perfect mix of paintings from your favorite artist, or maybe there was a different classic family photo on each month, and you’d be happy to see them all again. Suppose you just used the calendar for keeping track of which date fell on which day of the week (rather than, say, writing down appointments on it), so that it’s still pristine. Why not just hang onto it and hang it up again the next time it’s accurate? How long will you have to wait? Continue reading

Nobel laureates: often worth meeting, when you have the chance

With the announcement of the 2016 Nobel Prizes this week, I’ve been reflecting back on my experiences at the 2015 Lindau Laureate Nobel Meeting. These meetings are held every year and “are designed to activate the exchange of knowledge, ideas, and experience between and among Nobel Laureates and young scientists.”

Although I was skeptical going in, attending the meeting gave me a lot of food for thought. This past summer (one year later), being interviewed by a reporter for the Süddeutsche Zeitung gave me the chance to process and articulate some of that.

However, the interview was in English, and print newspapers have space constraints. Hence, for the resulting article (which published back in June), my answers to the interview questions had to be a.) severely abridged, and b.) translated into German. Therefore, I thought it might be worthwhile to post my original*, long-form responses here.

* with some links added and a few typos corrected
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My favorite things about today’s LIGO press conference

As you’ve no doubt already heard, it was announced earlier today that the Laser Interferometer Gravitational-wave Observatory (LIGO) has detected gravitational waves1 — i.e., ripples in space-time, which in this case were produced by a merger of two black holes that took place about 1.3 billion years ago (and, accordingly, 1.3 billion light years away) over the course of about 20 milliseconds.

Yes, ripples in space-time are a real thing; they are a predication of the theory of general relativity (which last year celebrated its centennial) and now they have also been measured. Serendipitously, the measurement itself also took place last year, on September 14, 2015 at 09:50:45 UTC (i.e., in the middle of the night at the detectors themselves, which are located in the U.S.), when those ripples finally reached Earth2.

This is a really, really impressive achievement. It involved decades of work on the part of thousands of people1, detectors that are miles in length, and the measuring of distances a tiny fraction of the size of a proton.

It’s thrilling to see how many quality write-ups there are out there about the news (e.g., BBC, NYT, NPR). You can get an explanation of the physics in comic form or in more detail, read about how the detection event went down (i.e., not exactly as planned, in that the machine hadn’t quite started its official “experiment run”), read an eloquent retrospective from a fellow Caltech professor, or even get a tour inside the facility.

Given all that great material, I don’t have much more to add in terms of explaining the physics . . . but watching the National Science Foundation’s live stream of the press conference produced a few highlights (besides the science itself, of course), which I didn’t want to let go unremarked.
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Push-up calculations: Feline facilitation, quantified

Not everyone thinks of cats as being big helpers, but mine seems to very much enjoy helping me with my workouts — with push-ups especially:

push-up partnerSome might say that she is actually hindering the doing of push-ups, which is technically true . . . but since the whole point of the exercise is, well, to exercise, the extra weight is ultimately helpful.

And it actually makes a difference! At least, it feels like it makes a difference. Despite her affinity for cookies (among other things), she only weighs about nine percent as much as I do; yet, push-ups feel more than nine percent harder when she’s up there. Is that just my perception? Or is there something about how the weight is distributed that gives her contribution a disproportional effect?

I decided to investigate the matter, breaking it up into three key questions:

1. How much force is actually required to do a push-up?

2. How does the addition of a medium-sized feline passenger increase the required force?

3. How much does additional force change the difficulty of the exercise — or, relatedly, the number of push-ups that one should expect to be able to do?

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The “problem” with Pi Day, and why I celebrate anyway

I confess, I’m a fan of \pi, the transcendental and irrational number that is the ratio of a circle’s circumference to its diameter and when written out in base 10 starts 3.14159 . . . Somewhat amusingly, I’m honestly not sure if this is confessing that I’m too much of a nerd/geek or not enough of one; we’ll get to that later, though.

I’m also a fan of pie, the dessert.

So is my cat. That is, she is a fan of pies, especially those with meringue on top. I don’t know how she feels about the number pi.

Last but not least, I’m a fan of puns and word play in general. Thus, it seems clear that I should be pulling out all the stops when when it comes to celebrating Pi Day (March 14th), especially this year (2015). As you probably already know, the best way to celebrate Pi Day is with pie.

So what’s the problem? Continue reading

What makes a thesis?

The second anniversary of finishing grad school seemed like an appropriate time to try to get this blog going again. This might go without saying, but writing a Ph.D. thesis* can really interfere with a person’s recreational science blogging. (Not that the time thereafter is necessarily much freer, at least not when starting a new job in a new sub-field, on a new continent, in a new country that speaks a different language . . . but that’s another matter.) Similarly, the topic of the Ph.D. thesis seemed like an appropriate one with which to start.

“How long will it take me to write my thesis?” is a question that every grad student must wonder at some point along the way — probably several points, in fact. I was wondering it just as I was starting** to write mine in February 2012, and I decided that strictly tracking the number of hours I invested in the project might both A.) be an interesting factoid, and B.) help me to better focus on the task.

Looking back at the data I’d taken and adding it up, the answer, it turned out, was approximately 283 hours — i.e., the equivalent of 11.8 24-hour days, 15.7 18-hour days, 23.6 12-hour days, or 35.4 8-hour days.
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Neil DeGrasse Tyson sure has a way with words

Edited together with some gorgeous footage from a variety of sources (ending with an actual Martian sunset!), the astrophysicist’s superbly eloquent answer to “What is the most astounding fact you can share with us about the universe?” yields a feast for the eyes, the ears, and the intellect:

(The Most Astounding Fact from Max Schlickenmeyer on Vimeo, via Slate)

I’ll even forgive Neil DeGrasse Tyson for his newfangled (18th century) use of “comprise” as a synonym for “constitute” or “compose.” (Clearly, we already have words that fill that role perfectly well. There was no need to introduce ambiguity and bastardize “comprise” by appropriating it, too!)

Jousting with giant piezoresistance

What Don Quixote thought were giants turned out to be windmills, and what researchers five years ago thought was giant piezoresistance appears, at least for now, to have been just as illusory. Unfortunately, that’s bad news for everyone who hoped to take advantage of this exciting property of miniscule silicon wires. But it is a very nice example of the scientific process at work.

What is piezoresistance anyway? And what good is it?

Normal-sized piezoresistance (or, more formally, “the piezoresistive effect”) is a change in the electrical resistivity of a material that results from mechanical stress — such as stretching or compression.

Piezoresistance was first discovered in the 1950s, and it occurs only in semiconductors. Unlike the considerably higher resistivity of insulators and considerably lower resistivity of conductors, the intermediate resistivity of semiconductors is sensitive to the tiny changes in the atomic structure of a material that occur when it is stretched or compressed.

There are lots of applications of the piezoresistive effect — again, this is normal-sized piezoresistance. Many commercial pressure sensors are based on the effect; they use the change in resistivity to measure the force on the sensor. At the forefront of research, the piezoresistive effect can provide an electronic measurement of nanoscale motion, such as that of a cantilever; this can be used both on man-made nanoscale systems and biological structures. It has also been found that mechanical stress can improve the performance of transistors via the same phenomenon.

The ephemeral promise of giant piezoresistance

Given all that piezoresistance can already do, there was significant excitement in 2006, when researchers at UC Berkeley’s Lawrence Berkeley National Laboratory published measurements of a piezoresistive effect nearly 40 times larger than it is in normal, bulk silicon. Continue reading