physics

N. David Mermin

N. David Mermin is a physics 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 N. David Mermin rather than just read about it. In short: Nathaniel David Mermin (; born 30 March 1935) is a solid-state physicist at Cornell University best known for the eponymous Hohenberg–Mermin–Wagner theorem, his application of the term "boojum" to superfluidity, his textbook with Neil Ashcroft on solid-state physics, and for contributions to the foundations of quantum mechanics and quantum information science. Education and career Mermin was born in 1935 in New Have…

Key takeaways

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

Reference excerpt

Nathaniel David Mermin (; born 30 March 1935) is a solid-state physicist at Cornell University best known for the eponymous Hohenberg–Mermin–Wagner theorem, his application of the term "boojum" to superfluidity, his textbook with Neil Ashcroft on solid-state physics, and for contributions to the foundations of quantum mechanics and quantum information science.

Education and career Mermin was born in 1935 in New Haven, Connecticut. He obtained a bachelor's degree in mathematics from Harvard University in 1956, graduating summa cum laude. He remained at Harvard for his graduate studies, earning a PhD in physics in 1961. After holding postdoctoral positions at the University of Birmingham and the University of California, San Diego, he joined the Cornell University faculty in 1964. He became a Cornell professor emeritus in 2006. Early in his career, Mermin worked in statistical physics and condensed-matter physics, including the study of matter at low temperatures, the behavior of electron gases, the classification of quasicrystals, and quantum chemistry. His later research contributions included work in quantum information science and the foundations of quantum mechanics. Mermin was the first to note how the three-particle GHZ state demonstrates that no local hidden-variable theory can explain quantum correlations, and together with Asher Peres, he introduced the "magic square" proof, another demonstration that attempting to "complete" quantum mechanics with hidden variables does not work. Richard Feynman described another paper by Mermin in this area as "one of the most beautiful papers in physics". In collaboration with Charles Bennett and Gilles Brassard, he made a significant early contribution to quantum cryptography. Starting in 2012, he has advocated the interpretation of quantum mechanics known as Quantum Bayesianism, or QBism. In 2003, the journal Foundations of Physics published a bibliography of Mermin's writing that included three books, 125 technical articles, 18 pedagogical articles, 21 general articles, 34 book reviews, and 24 "Reference Frame" articles from Physics Today. Mermin was elected a Fellow of the American Physical Society in 1969, and he was elected a member of the National Academy of Sciences in 1991. He was also elected a member of the American Philosophical Society in 2015.

Word and phrase coinages Inspired by Lewis Carroll's comic poem The Hunting of the Snark, Mermin introduced the term boojum into the vocabulary of condensed-matter physics. In his book It's About Time (2005), one of several expository pieces on special relativity, he suggests that the English foot (0.3048 meters) be slightly modified to approximately 0.2998 m. This adaptation of a physical unit is one of several ploys that Mermin uses to draw students into spacetime geometry. In the book, Mermin writes:

Henceforth, by 1 foot we shall mean the distance light travels in a nanosecond. A foot, if you will, is a light nanosecond (and a nanosecond, even more nicely, can be viewed as a light foot). ... If it offends you to redefine the foot ... then you may define 0.299792458 meters to be 1 phoot, and think "phoot" (conveniently evocative of the Greek φωτος, "light") whenever you read "foot". Though it is often misattributed to Richard Feynman, Mermin coined the phrase "shut up and calculate!" to characterize the views of many physicists regarding the interpretation of quantum mechanics.

Books 1968: Space and Time in Special Relativity, McGraw Hill ISBN 0-88133-420-0 1976: (with Neil Ashcroft) Solid State Physics, Holt, Rinehart and Winston ISBN 0-03-083993-9 1990: Boojums All the Way Through, Cambridge University Press ISBN 0-521-38880-5 2005: It's About Time: Understanding Einstein's Relativity, Princeton University Press ISBN 978-0-691-12201-4 2007: Quantum Computer Science, Cambridge University Press ISBN 978-0-521-87658-2 2016: Why Quark Rhymes with Pork: and Other Scientific Diversions, Cambridge University Press ISBN 978-1-107-02430-4

References

Further reading Greenberger, Daniel; Shimony, Abner (2003). "The Presence of David Mermin". Foundations of Physics. 33 (10): 1419–1422. Bibcode:2003FoPh...33.1419G. doi:10.1023/A:1026033228750. S2CID 118831799. Shimony, Abner (2003). "Four Poems dedicated to David Mermin". Foundations of Physics. 33 (11): 1699–1700. Bibcode:2003FoPh...33.1699S. doi:10.1023/A:1026069319123. S2CID 115707714. Mermin, N. David (2024). "Autobiographical Notes of a Physicist". Physics in Perspective. 26 (1): 3. arXiv:2401.04711. Bibcode:2024PhP....26....3M. doi:10.1007/s00016-024-00310-z.

External links

Mermin's homepage N. David Mermin publications indexed by Google Scholar

Illustrations

Worked examples

Example 1 — a first encounter with N. David Mermin

Start with the simplest possible case. Write down what N. David Mermin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 N. David Mermin 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 N. David Mermin 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 N. David Mermin

In research: N. David Mermin appears in physics 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 N. David Mermin 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: N. David Mermin is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1935 births, 21st-century American physicists, Cornell Laboratory of Atomic and Solid State Physics, so understanding it makes those chapters shorter.
In everyday life: Look for N. David Mermin 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 N. David Mermin in 20 minutes

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

Frequently asked questions

What is N. David Mermin in simple terms?

Why does N. David Mermin matter?

Because it connects several physics 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 N. David Mermin?

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 N. David Mermin.