astronomy

William Markowitz

William Markowitz 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 William Markowitz rather than just read about it. In short: William Markowitz (February 8, 1907 – October 10, 1998) was an American astronomer known for his work on the standardization of time. Early life and education William Markowitz was born Melč in Austrian Silesia (now in the Czech Republic) on February 8, 1907.

Key takeaways

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

Reference excerpt

William Markowitz (February 8, 1907 – October 10, 1998) was an American astronomer known for his work on the standardization of time.

Early life and education William Markowitz was born Melč in Austrian Silesia (now in the Czech Republic) on February 8, 1907. His mother had been visiting from her native Poland. The family emigrated to the United States in 1910, settling in Chicago. Markowitz obtained his doctorate from the University of Chicago in 1931 under the supervision of William Duncan MacMillan with a thesis on the statistics of binary stars.

Career He taught at Pennsylvania State College before joining the United States Naval Observatory in 1936, working under Paul Sollenberger and Gerald Clemence in the time service department. Markowitz eventually became director of the department. He developed the ephemeris time scale, which had been adopted by the IAU in 1952 on a proposal formulated by Clemence in 1948, as an international time standard. He subsequently worked with Louis Essen in England to calibrate the newly developed atomic clocks in terms of the ephemeris second. The fundamental frequency of caesium atomic clocks, which they determined as 9,192,631,770 ± 20 Hz, was used to define the second internationally since 1967. At the International Astronomical Union (IAU) meeting in Dublin in 1955, he had proposed the system of distinguishing between variants of Universal Time, as UT0 (UT as directly observed), UT1 (reduced to invariable meridian by correcting to remove effect of polar motion) and UT2 (further corrected to remove (extrapolated) seasonal variation in Earth rotation rate), a system which remains in some use today. He served as President of the IAU commission on time from 1955 to 1961, and was active in the International Union of Geodesy and Geophysics, the American Geophysical Union, and the International Consultative Committee for the Definition of the Second. After retiring from USNO in 1966, Markowitz served as professor of physics at Marquette University until 1972, and also held a post at Nova Southeastern University.

Personal life Markowitz married Rosalyn Shulemson in 1943. Markowitz died on October 10, 1998 at the age of 91.

References

Sources Dick, Steven J.; McCarthy, Dennis D. (January 1, 1999). "William Markowitz (1907–1998)". Bulletin of the American Astronomical Society. 31 (4): 1605. Bibcode:1999BAAS...31.1605D.

Illustrations

Worked examples

Example 1 — a first encounter with William Markowitz

Start with the simplest possible case. Write down what William Markowitz 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 William Markowitz 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 William Markowitz 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 William Markowitz

In research: William Markowitz 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 William Markowitz 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: William Markowitz is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1907 births, 1998 deaths, American astronomers, so understanding it makes those chapters shorter.
In everyday life: Look for William Markowitz 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 William Markowitz in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what William Markowitz 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 William Markowitz out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is William Markowitz in simple terms?

William Markowitz (February 8, 1907 – October 10, 1998) was an American astronomer known for his work on the standardization of time. Early life and education William Markowitz was born Melč in Austrian Silesia (now in the Czech Republic) on February 8, 1907.

Why does William Markowitz 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 William Markowitz?

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 William Markowitz.