astronomy

Smoot

Smoot is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Smoot rather than just read about it. In short: The smoot is a nonstandard, humorous unit of length created as part of an MIT fraternity pledge to Lambda Chi Alpha by Oliver R. Smoot, who in October 1958 lay down repeatedly on the Harvard Bridge between Boston and Cambridge, Massachusetts, so that his fraternity brothers could use his height to measure the length of the bridge.

Key takeaways

Smoot belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Smoot to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Smoot from memory before moving on to harder problems.

Reference excerpt

The smoot is a nonstandard, humorous unit of length created as part of an MIT fraternity pledge to Lambda Chi Alpha by Oliver R. Smoot, who in October 1958 lay down repeatedly on the Harvard Bridge between Boston and Cambridge, Massachusetts, so that his fraternity brothers could use his height to measure the length of the bridge.

Description One smoot is equal to Oliver Smoot's height at the time of the pledge, 5 feet 7 inches (1.7018 m). The bridge's length was measured to be 364.4 smoots (2,035 ft; 620.1 m) "± 1 εar" with the "±" showing measurement uncertainty and "ear" spelled with an epsilon to further indicate possible error in the measurement. Over the years the "±" portion and "ε" spelling have been left out in many citations, including some markings at the site itself, but the "±" is recorded on a 50th-anniversary plaque at the end of the bridge.

History

Oliver R. Smoot was selected by his Lambda Chi Alpha fraternity pledgemaster because he was deemed shortest—which made measuring the bridge the most labor-intensive—and he was the "most scientifically named." Smoot repeatedly lay down on the bridge, let his companions mark his new position in chalk or paint, and then got up again. Eventually, he wearied of the exercise and was carried thereafter by the fraternity brothers to each new position. Smoot graduated from MIT in 1962, and then attended Georgetown University Law Center in Washington, D.C., where he obtained his Juris Doctor. He served as chairman of the American National Standards Institute from 2001 to 2002, and then as president of the International Organization for Standardization from 2003 to 2004. Public knowledge and interest in the story began when Holiday investigated the marks on the bridge years later, and published an interview with Smoot. The prank's fiftieth anniversary was commemorated on October 4, 2008, as Smoot Celebration Day at MIT, which Smoot attended. A 2016 April Fools' Day article by the MIT Alumni Association announced that MIT would recalibrate the smoot to 65.7500 inches (1.67005 m) and the ear to 2.48031 inches (62.999874 mm), and the bridge would thus be 372 smoots, give or take 11 ears.

On May 7, 2016, Smoot served as grand marshal of the alumni parade across the bridge, celebrating the 100th anniversary of MIT's move from Boston to Cambridge.

Practical use The bridge is marked with painted markings indicating how many smoots there are from where the sidewalk begins on the Charles River bank in Boston, with a number every ten smoots. The marks were repainted each semester by the incoming associate member class (similar to pledge class) of Lambda Chi Alpha before they were suspended due to repeated infractions of MIT's alcohol rules. Lambda Chi Alpha alumni, along with current students of MIT, have maintained the markings.

Markings typically appear every 10 smoots (56 ft; 17 m), but additional marks appear at other numbers in between. For example, the 70-smoot (390 ft; 120 m) mark is accompanied by a mark for 69. The 182.2-smoot (1,017 ft 3 in; 310.1 m) mark is accompanied by the words "Halfway to Hell" and an arrow pointing towards MIT. The markings are recognized as milestones on the bridge, to the degree that during bridge renovations in the 1980s, the Cambridge, Massachusetts, police department requested that the markings be restored, since they were routinely used in police reports to identify locations on the bridge. The renovators at the Massachusetts Highway Department also scored the concrete surface of the sidewalk on the bridge at 5-foot-7-inch (1.70 m) intervals instead of the conventional 6 feet (1.83 m). The Lambda Zeta (MIT) chapter of Lambda Chi Alpha, which created the smoot markings, continues to repaint the markings once or twice per year. Starting in 2011, Google Earth enabled the ability to measure distance using smoots, with the standard length of 5 feet 7 inches. The calculator function of Google Search also provides values in smoots, and in 2011, smoot was one of the 10,000 new words added to the fifth edition of The American Heritage Dictionary. Robert Tavernor's book covering the history of measurement is titled Smoot's Ear: The Measure of Humanity. MIT's student-run college radio station WMBR gives its broadcasting wavelength as two smoots (3.4036 m), closely approximating 88.1 MHz (3.4029 m).

Illustrations

Worked examples

Example 1 — a first encounter with Smoot

Start with the simplest possible case. Write down what Smoot claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Smoot before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Smoot ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Smoot

In research: Smoot appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Smoot in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Smoot is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1958 introductions, Culture of Massachusetts, Eponyms, so understanding it makes those chapters shorter.
In everyday life: Look for Smoot outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Smoot in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Smoot means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Smoot out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Smoot in simple terms?

Why does Smoot matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Smoot?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Smoot.