physics

Leslie Lawrance Foldy

Leslie Lawrance Foldy 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 Leslie Lawrance Foldy rather than just read about it. In short: Leslie Lawrance Foldy (1919–2001) was a theoretical physicist, who made contributions to condensed matter physics and quantum mechanics. Early life Foldy was born László Földi in Kisszeben, Hungary (today Slovakia), on October 26, 1919.

Key takeaways

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

Reference excerpt

Leslie Lawrance Foldy (1919–2001) was a theoretical physicist, who made contributions to condensed matter physics and quantum mechanics.

Early life Foldy was born László Földi in Kisszeben, Hungary (today Slovakia), on October 26, 1919. In 1920, his family moved to the USA due to the invasion of Hungary around that time, and there he was known as Leslie Foldy.

Education His high school education was in Cleveland, Ohio, and at that time he called his middle name "Lawrance", upon noticing he hadn't a middle name while the other students had. While at high school, he picked up an interest in physics. In 1941, Foldy graduated with a B.S. degree in physics from the Case School of Applied Science (now renamed to the Case Western Reserve University), his senior thesis was on crystal lattice vibrations.

Research He started his PHD in 1945 at the University of California, Berkeley, in J. Robert Oppenheimer's group, and with Luis Alvarez and David Bohm, until 1947. In 1948 he completed his doctoral degree at the Institute for Advanced Study, and later returned to the Case Institute of Technology as an assistant professor of physics. In 1949 at the University of Rochester, Foldy and Siegfried Adolf Wouthuysen, working with Robert Marshak, wrote a preprint on the nonrelativistic limit of the Dirac equation. In 1950 at Michigan, their work was criticized as erroneous, motivating Foldy and Wouthuysen to make their calculations clear and efficient. A transformation forming part of their calculations is now called the Foldy–Wouthuysen transformation. Positions he held at the Institute for Advanced Study include:

Fulbright Fellow, 1953–54 Guggenheim Fellow, 1953–54 NSF Sr Postdoc Fellow, 1963–64

References P. L. Taylor; W. J. Fickinger (2007). "In Appreciation, Multiple Scattering: Leslie Foldy's Winding Road Through Physics" (PDF). Physics in Perspective. 9 (3): 346. Bibcode:2007PhP.....9..346T. doi:10.1007/s00016-007-0338-2. Archived from the original (PDF) on 2014-08-21. "Community of Scholars Profile: Foldy, Leslie Lawrence". Institute for advanced study. Retrieved 2013-06-19. R. W. Brown, L. M. Krauss, P. L. Taylor (December 2001). "Obituaries: Leslie Lawrance Foldy". Physics Today. 54 (12): 75. Bibcode:2001PhT....54l..75B. doi:10.1063/1.1445566.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links L. L. Foldy. "Origins of the FW Transformation: A Memoir" (PDF)., Appendix G

Worked examples

Example 1 — a first encounter with Leslie Lawrance Foldy

Start with the simplest possible case. Write down what Leslie Lawrance Foldy 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 Leslie Lawrance Foldy 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 Leslie Lawrance Foldy 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 Leslie Lawrance Foldy

In research: Leslie Lawrance Foldy 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 Leslie Lawrance Foldy 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: Leslie Lawrance Foldy is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1919 births, 2001 deaths, 20th-century American physicists, so understanding it makes those chapters shorter.
In everyday life: Look for Leslie Lawrance Foldy 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 Leslie Lawrance Foldy in 20 minutes

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

Frequently asked questions

What is Leslie Lawrance Foldy in simple terms?

Leslie Lawrance Foldy (1919–2001) was a theoretical physicist, who made contributions to condensed matter physics and quantum mechanics. Early life Foldy was born László Földi in Kisszeben, Hungary (today Slovakia), on October 26, 1919.

Why does Leslie Lawrance Foldy 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 Leslie Lawrance Foldy?

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 Leslie Lawrance Foldy.