What I Learned Today

On a lark, I signed up last weekend for the National Adult Spelling Bee, to be held this Sunday in Long Beach. The website helpfully provides a list of words that were used in last year’s competition as well as an interactive online spelling bee with which you can practice. So far I’ve compiled a hefty list of words on which I would have failed, had I been called upon to spell them. (I note there is a difference between recognizing a word as printed and translating from the word spoken aloud to its printed form — so there are words that I could read but might not be able to spell aloud.) Let’s hope none of them make an appearance Sunday, or that I remember their proper spellings!

• souk: an Arab marketplace or bazaar
• escutcheon: a shield or emblem bearing a coat of arms
• weir: a low dam built across a river to regulate its flow
• vichyssoise: a soup made with potatoes, leeks, and cream
  
• mahout: a person who tends an elephant

• etouffee: a spicy Cajun stew made with vegetables and seafood
• axolotl: a Mexican salamander
• adrenergic: activated by or capable of releasing epinephrine (are you kidding me?)
• tremolo: a wavering effect in a musical tone
• gabion: a wirework container filled with rock, broken concrete, or other material, used to construct dams
• … and so on…

I’m also concerned about homonyms. What if “philter” or “burgher” or “mien” comes up and it doesn’t occur to me to ask for a definition before spelling it? (Oh, whew, the rules indicate that in the case of homonyms, the pronouncer is to state which of the meanings is intended.)

I don’t actually care if I win. My goal is rather more humble: to misspell a word that I genuinely don’t know, instead of misspelling a word because of a stupid mistake, as in my fifth grade spelling bee when I was asked to spell “alcohol” and hastily began with “a-c-” and then stopped, because you can’t correct yourself. Not this time! This time, I will be slain with honor by budgerigar or gangue or rasorial or the like! If all goes well.

I posted previously about a dramatic biscuit failure I experienced when I forgot to include baking powder, due to a careless reading of the recipe. Instead of regular flour, it called for “self-rising flour”, which already has baking powder mixed in. The strange thing is, no one seems to agree on exactly how much baking powder should go into self-rising flour. Casual googling turned up recommendations for 0.5 tsp, 1 tsp, 1.25 tsp, and 1.5 tsp (same as 0.5 Tbsp) as the amount of baking powder to add for each 1 cup of flour.

Now the difference between 0.5 and 1.5 tsp may not sound like a lot, but consider that it represents a 50% increase or decrease from a middle value of 1.0 tsp. For something as sensitive to stoichiometry as baking is, I’d expect that to make a difference. Then again, it seems reasonable that the desired amount would vary depending on the item being baked and how much loft you hope to get — which sort of defeats the purpose of a pre-mixed flour-baking powder product.

But even specialized biscuit recipes disagree on this, but seem to choose either 1 tsp or 0.5 Tbsp (1.5 tsp, in agreement with my mom’s recipe). (As a side note, they also vary widely on how much shortening or butter to use, as well as how much milk or buttermilk to use and whether or not to chill the dry ingredients + butter. The number of permutations sent me into a brief paralysis (gosh darn it, shouldn’t we have converged on a solution by now?!) until I decided to give up on the web and just use my mom’s recipe.)

I decided that a scientific test was called for. I split up the flour involved in a batch of biscuits (2 cups) into three bowls, for baking powder:flour ratios of 1 tsp:1 cup, 1.5 tsp:1 cup, and 2 tsp:1 cup. There was enough material to make two full biscuits of each type, plus some extra left over for a partial-biscuit. I measured the biscuit height before and after baking. The following chart shows the average (across two biscuits) difference in height I observed (data points in blue, average in red).

A clear difference emerged! It’s even almost linear, which is a bit surprising given the small sample size. Now it would be interesting to try even smaller and larger amounts of baking powder… the curve is likely to have an interesting shape at both ends. But for food, one of the most important measures of success is not size, but taste. I sampled all of the results and found that I couldn’t really tell a difference between the 1.5- and 2-tsp results, but the 1-tsp biscuits were noticeably less fluffy. I conclude that the wise biscuit baker should avoid self-rising flour with less than 1.5 tsp of baking powder per cup of flour (or avoid it altogether and just add your own ingredients).

Some other notes:

• One of the annoyingly tedious parts of making biscuits or scones is the “cutting in” step that gets the fat (butter or shortening or whatnot) into the flour. I used a tip from my friend Evan: freeze the butter, then use a cheese grater to shred it into the flour. Mix with fingers. Works like a charm!
• Some biscuit recipes call for milk, some for milk with lemon juice added, and some for buttermilk. Ever wondered why? Well, adding lemon juice or using buttermilk lowers the pH of the liquid (makes it more acidic). And chemical leaveners such as baking powder and baking soda are basic, therefore in theory should react more strongly in an acidic environment (giving your baked good more “rise”). But baking powder is baking soda pre-combined with its own acid (cream of tartar). So you shouldn’t actually need an acidic liquid. I tested this by dropping some baking powder in water, then in buttermilk. If anything, the baking powder reacted more to the water than the buttermilk. (I should do the same test with baking soda.) This also explains (maybe) why some recipes use baking powder and others use baking soda + cream of tartar — the latter want control over the ratio, just like the self-rising-flour issue!
• Biscuit aficionados recommend the use of flour with a lower protein content (to get even more loft) such as cake flour; see How to make the best Buttermilk Biscuits from Scratch. I haven’t tried this one yet, either.
• I actually did a parallel experiment, with the same three types of mixtures, but first chilling the dry ingredients + butter. However, a distraction at a critical moment caused me to forget to measure the biscuits before they went into the oven! So I only have their post-baking heights. If anything, the relationship seemed weaker, with less rising action. While a firm conclusion should await more reliable data, for now I’m going on the assumption that the chilling step is unnecessary. (Taste is unaffected, too ;) )

Clearly, the field of interesting experiments with ingredient combinations is a rich and open one, even just for making biscuits!

Mark Twain is one of my absolute favorite authors. (If I’d realized his brilliance a little earlier, I might have avoided detention in middle school.) I’ve particularly enjoyed Roughing It (including his tales of traveling through Utah (and meeting Brigham Young), setting a forest fire near Mono Lake, crunching across barely-cooled lava in Kilauea, and other amazing adventures), Letters to the Earth (with hilarious retellings of Adam and Eve’s first experiences in the world), At a Fire (satire of an etiquette book likely titled “At a Dance”, which would have indicated the order in which ladies may be asked to dance, etc.), and a dinner speech on the crazy English alphabet (don’t worry, he picked on German, too), and more.

But I never thought of being Mark Twain myself.

To promote a new book on Twain trivia, the Twainia folks are having a competition titled “I Am The Next Mark Twain.” Contestants are to read an unfinished piece by Twain (Conversations with Satan) and finish it, using up to 300 words. Entries will be judged 50% on “originality of idea/creativity” and 50% on “writing style”. Entries are due May 31. I’m immediately intrigued. Who’s in it with me?

Another interesting Twain resource: The Mark Twain Project is working to put all of Twain’s writings (including his letters) online in a central location. Not only do they provide access to the texts, but they also provide a split-pane view so you can see the original text plus edits that were made and explanatory notes side-by-side. In some cases, you can also see a scanned version of the original handwritten version (mainly for letters). (It reminds me a little of the marvelous online version of Darwin’s works.) To date, only some of his letters have been added to the archive, but they make for delightful reading, including his courtship letters to his future wife, Livy. And more is in the works!

Clever astronomers have come up with many different, creative ways to detect extrasolar planets orbiting around other stars. We’re up to 346 planets detected now, by a variety of different methods including transit detection, radial velocity analysis, precision astrometry, and direct imaging. At the Missions for Exoplanets meeting today, I learned about another method that relies on serendipity but, when it happens, provides inarguable evidence for a planet.

Gravitational microlensing refers to the brief magnification we observe when a dimmer, closer star passes between us and a brighter, distant star. Gravitational effects cause the distant star to temporarily become even brighter (because its light is being bent and focused towards us). If the closer star (the “lensing” star) also has one or more planets, then the resulting light curve gets an extra bump from the planet’s “micro”-lensing effect.

Scott Gaudi of Ohio State University created this marvelous animation of microlensing in action, which also shows how it is detected. (I love the symbolic fraction!) The distant star is the red circle, the closer star is in orange, the distant star’s apparent position is in blue, and the closer star’s planet is the brown dot.

What’s neat about this phenomenon is that although no one yet seems up for predicting when and where it might happen next, as soon as the characteristic increase in brightness begins, teams across the globe are alerted and start watching, hoping to capture the planet’s bump (if any) when it happens. In fact, amateur observers have contributed key observational data that helped find a new planet.

Maybe I should break down and get a telescope already.

The NRAO (National Radio Astronomy Observatory) offers online what just may be the coolest try-this-at-home project ever. How often do you get to do your own cosmology, with no equipment and no training? Well, now you can, by going through the measure the age of the universe tutorial.

Given the observation that all other galaxies are moving away from us (which is observable due to the Doppler effect, which manifests itself as a redshift in the light they emit), and assuming that other spiral galaxies are about the same size as ours (yes, quite an assumption), then using our current estimate of the size of our galaxy, we can convert the apparent size of another galaxy into its distance from us.

Then, we record the distribution of redshifts coming from the galaxy (different parts will shift by different amounts since some may be spinning towards us and some away) and convert those shifts into a velocity. For precision, we look at one particular wavelength (the radio spectral line of hydrogen, here).

Finally, we plot distance versus velocity to get the relationship between those two variables. Edwin Hubble‘s great discovery, after going through this same process, was that more distant galaxies are more red-shifted, and therefore moving faster — thus, there is some sort of acceleration going on. The slope of a line fit to these data points gives us that acceleration, which is referred to as the Hubble constant, H₀. Since this constant (slope) is velocity divided by distance, it has units of 1/time. Therefore, if you take its reciprocal, you get time itself: the age of the universe.

I downloaded the 10 example galaxies provided in the tutorial (and you can, too) and calculated distance and velocity values for each one. I felt more confident in my ability to estimate the velocity (average of the observed values) than for the distance, which is very sensitive to the angular size, which is extremely hard to be precise about with a paper ruler. :) I’m assuming that whoever prepared these examples already adjusted the images so that they all have the same scale. Since not all galaxies are perpendicular to us (some are tilted away), I used the largest diameter I could find. My observations are shown below, plotted against the line obtained using the current best estimate of Hubble’s constant (derived from thousands of observations, not just 10!). While I didn’t get a perfect linear relationship, apparently this isn’t expected due to relativity and other confounding factors. Hubble himself used 46 galaxies and ended up much, much further off (apparently due to “peculiar velocities” and poor calibration on distances).

Each galaxy provides an estimate of the age of the universe. Using these 10 galaxies, my estimates ranged from 10.0 to 39.8 billion years old. Excluding the crazy outlier (NGC 4214, which is the only one with an estimate outside the standard deviation), my estimate of the age of the universe is 14.2 billion years old. Not too far off the latest best estimate of 13.8 billion years!

And what of NGC 4214? It turns out that it isn’t a spiral galaxy at all, which could explain why it didn’t fit with the others. Its redshift indicates that it isn’t going very fast, so shouldn’t be very far away, but it appears to be very small given its proximity. I’m guessing that it’s much smaller than the 10 kpc that was used as the assumed size for all galaxies in this study. In fact, I found that its diameter has been determined to be only 6.7 kpc. So it’s a true outlier, not just due to measurement error.

Science is awesome.