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Julian Schwinger

Julian Schwinger 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 Julian Schwinger rather than just read about it. In short: Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was an American theoretical physicist. He shared the 1965 Nobel Prize in Physics with Richard Feynman and Shin'ichirō Tomonaga "for their fundamental work in quantum electrodynamics (QED), with deep-ploughing consequences for the physics of elementary particles".

Julian Schwinger — main illustration
Julian Schwinger — illustration

Key takeaways

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

Reference excerpt

Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was an American theoretical physicist. He shared the 1965 Nobel Prize in Physics with Richard Feynman and Shin'ichirō Tomonaga "for their fundamental work in quantum electrodynamics (QED), with deep-ploughing consequences for the physics of elementary particles". He developed a relativistically invariant perturbation theory, and renormalized QED to one loop order. Schwinger was a physics professor at several universities. Schwinger is recognized as an important physicist, responsible for much of modern quantum field theory, including a variational approach, and the equations of motion for quantum fields. He developed the first electroweak model, and the first example of confinement in 1+1 dimensions. He is responsible for the theory of multiple neutrinos, Schwinger terms, and the theory of the spin-3/2 field. He shared the inaugural Albert Einstein Award with Kurt Gödel.

Biography

Early life and career Julian Seymour Schwinger was born in New York City, to Ashkenazi Jewish parents, Belle (née Rosenfeld) and Benjamin Schwinger, a garment manufacturer, who had emigrated from Poland to the United States. Both his father and his mother's parents were prosperous clothing manufacturers, although the family business declined after the Wall Street Crash of 1929. The family followed the Orthodox Jewish tradition. Julian's older brother Harold Schwinger was born in 1911, seven years before Julian who was born in 1918. Schwinger was a precocious student. He attended the Townsend Harris High School from 1932 to 1934, a highly regarded high school for gifted students at the time. During high school, Julian had already started reading Physical Review papers by authors such as Paul Dirac in the library of the City College of New York, in whose campus Townsend Harris was then located. He published his first paper when he was seventeen. In the fall of 1934, Schwinger entered the City College of New York as an undergraduate. CCNY automatically accepted all Townsend Harris graduates at the time, and both institutions offered free tuition. Due to his intense interest in physics and mathematics, Julian performed very well in those subjects despite often skipping classes and learning directly from books. On the other hand, his lack of interest for other topics such as English led to academic conflicts with teachers of those subjects. After Julian had joined CCNY, his brother Harold, who had previously graduated from CCNY, asked his ex-classmate Lloyd Motz to "get to know [Julian]". Lloyd was a CCNY physics instructor and Ph.D. candidate at Columbia University at the time. Lloyd made the acquaintance, and soon recognized Julian's talent. Noticing Schwinger's academic problems, Lloyd decided to ask Isidor Isaac Rabi who he knew at Columbia for help. Rabi also immediately recognized Schwinger's capabilities on their first meeting, and then made arrangements to award Schwinger with a scholarship to study at Columbia. At first Julian's bad grades in some subjects at CCNY prevented the scholarship award. But Rabi persisted and showed an unpublished paper on quantum electrodynamics written by Schwinger to Hans Bethe, who happened to be passing by New York. Bethe's approval of the paper and his reputation in that domain were then enough to secure the scholarship for Julian, who then transferred to Columbia. His academic situation at Columbia was much better than at CCNY. He was accepted into the Phi Beta Kappa society and received his B.A. in 1936. During Schwinger's graduate studies, Rabi felt that it would be good for Julian to visit other institutions around the country, and Julian was awarded a travelling fellowship for the year 37/38 which he spent working with Gregory Breit and Eugene Wigner. During this time, Schwinger, who previously had already had the habit of working until late at night, went further and made the day/night switch more complete, working at night and sleeping during the day, a habit he would carry throughout his career. Schwinger later commented that this switch was in part a way to retain greater intellectual independence and avoid being "dominated" by Breit and Wigner by simply reducing the duration of contact with them by working different hours. Schwinger obtained his PhD overseen by Rabi in 1939 at the age of 21. During the fall of 1939 Schwinger started working at the University of California, Berkeley under J. Robert Oppenheimer, where he stayed for two years as an NRC fellow. On June 8, 1947, Schwinger married Clarice Carrol. They had no children.

… excerpt ends here. Continue reading the full article.

Illustrations

Julian Schwinger illustration
Julian Schwinger: Julian Schwinger, winner of the 1965 Nobel Prize in Physics. Original caption: "His laboratory is his ballpoint pen."
Julian Schwinger, winner of the 1965 Nobel Prize in Physics. Original caption: "His laboratory is his ballpoint pen."
Julian Schwinger: The headstone of Julian Schwinger at Mt. Auburn Cemetery in Cambridge, MA.
The headstone of Julian Schwinger at Mt. Auburn Cemetery in Cambridge, MA.

Worked examples

Example 1 — a first encounter with Julian Schwinger

Start with the simplest possible case. Write down what Julian Schwinger 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 Julian Schwinger 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 Julian Schwinger 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 Julian Schwinger

In research
Julian Schwinger 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 Julian Schwinger 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
Julian Schwinger is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1918 births, 1994 deaths, 20th-century American Jews, so understanding it makes those chapters shorter.
In everyday life
Look for Julian Schwinger 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 Julian Schwinger in 20 minutes

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

Frequently asked questions

What is Julian Schwinger in simple terms?

Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was an American theoretical physicist. He shared the 1965 Nobel Prize in Physics with Richard Feynman and Shin'ichirō Tomonaga "for their fundamental work in quantum electrodynamics (QED), with deep-ploughing consequences for the physic…

Why does Julian Schwinger 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 Julian Schwinger?

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 Julian Schwinger.

Tags

  • 1918 births
  • 1994 deaths
  • 20th-century American Jews
  • 20th-century American physicists
  • American Nobel laureates
  • American particle physicists
  • American people of Polish-Jewish descent
  • American quantum physicists
  • American theoretical physicists
  • Burials at Mount Auburn Cemetery
  • Columbia College, Columbia University alumni
  • Columbia Graduate School of Arts and Sciences alumni

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