physics

James A. Isenberg

James A. Isenberg 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 James A. Isenberg rather than just read about it. In short: James A. Isenberg (born 1951) is an American theoretical physicist and mathematician, professor emeritus at the University of Oregon.

Key takeaways

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

Reference excerpt

James A. Isenberg (born 1951) is an American theoretical physicist and mathematician, professor emeritus at the University of Oregon.

Personal life and education Isenberg was born in 1951 in Boston. He became an Eagle Scout in 1966, and in 1969 graduated as valedictorian from Plymouth-Whitemarsh High School in Plymouth Meeting, Pennsylvania, where he was also selected as one of the top 40 finalists in the Westinghouse Science Talent Search. When he ran the Boston Marathon at age 18, The Philadelphia Inquirer reported he "is 5 feet 1 inch tall, weighs 95 pounds and looks about 13." He wore his birth certificate pinned to his jersey to prove his age. He also ran in the inaugural 1970 New York City Marathon. Isenberg says he has "completed 143 marathons, including 30 Boston Marathons." At Princeton University he graduated summa cum laude with an A.B. in physics in 1973. While at Princeton, he earned varsity letters in cross-country, wrestling, and track, and was awarded the Class of 1916 Cup upon graduating. He was a graduate student under Charles Misner at the University of Maryland, and he earned a Ph.D. in physics in 1979, with his dissertation, Construction of Spacetimes from Initial Data. In December 2017 at Bondi Beach in Sydney, Australia, Isenberg was standing in the ocean when a wave knocked him over, injuring his spinal cord and leaving him paralyzed from the neck down. He received care at Thomas Jefferson University Hospital before transferring to Magee Rehabilitation Hospital in Philadelphia. In 2019 at the Princeton alumni parade, he "led his class down the route in a wheelchair". Isenberg lives in McLean, Virginia, with his wife, economist Pauline Kennedy.

Career Isenberg is one of the pioneers in the study of the constraint equations in classical general relativity. His many important contributions include the completion of the solution theory of the constraint equations on closed manifolds with constant mean curvature, and with his collaborators, the first nontrivial results on the non-constant mean curvature case. From 1973 to 1979, Isenberg held positions in the physics department at the University of Maryland. Between 1979 and 1982 he held a postdoctoral fellow positions in the applied mathematics department of the University of Waterloo and the mathematics department at the University of California, Berkeley. Isenberg joined the mathematics department faculty at the University of Oregon in 1982 and in 2021 became a professor emeritus of mathematics at the University of Oregon.

Recognition Isenberg was elected a Fellow of the American Physical Society in 2000, cited "For his pioneering work on global issues in general relativity and for his contributions to the field." The American Physical Society recognized Isenberg as a 2023 recipient of the 5 Sigma Physicist Honor for his science policy advocacy work. He was named to the 2021 class of fellows of the American Mathematical Society "for contributions to mathematical general relativity and geometry flows". The Pacific Coast Gravity Meeting was initiated by Isenberg in 1985, along with Kip Thorne, Gary Horowitz, and James Hartle. The conference has been dedicated to Isenberg as of the 34th meeting at Caltech in 2018 and is now known as the Jim Isenberg Pacific Coast Gravity Meeting.

Selected works Chow, Bennett; et al. (2007–2015). The Ricci Flow: Techniques and Applications. Mathematical Surveys and Monographs. Vol. 135, 144, 163, 206. American Mathematical Society. Isenberg, J. (1995). "Constant mean curvature solution of the Einstein constraint equations on closed manifold". Class. Quantum Grav. 12 (9): 2249–2274. Bibcode:1995CQGra..12.2249I. doi:10.1088/0264-9381/12/9/013.

References

External links Jim Isenberg - The Conformal Method and Solutions of the Einstein Constraint Equation on YouTube (video, 1:01:12 hours) Symmetries of Cosmological Cauchy Horizons with Non-Closed Orbits - Jim Isenberg on YouTube (video, 38:43 minutes) Ricci Flow - Numberphile on YouTube (video, 14:40 minutes) Recent Results on Ricci Flow - Jim Isenberg Some Recent Results on Ricci Flow - Jim Isenberg on YouTube (video, 1:00:00 hour)

Illustrations

Worked examples

Example 1 — a first encounter with James A. Isenberg

Start with the simplest possible case. Write down what James A. Isenberg 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 James A. Isenberg 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 James A. Isenberg 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 James A. Isenberg

In research: James A. Isenberg 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 James A. Isenberg 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: James A. Isenberg is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1951 births, 21st-century American physicists, American relativity theorists, so understanding it makes those chapters shorter.
In everyday life: Look for James A. Isenberg 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study James A. Isenberg in 20 minutes

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

Frequently asked questions

What is James A. Isenberg in simple terms?

James A. Isenberg (born 1951) is an American theoretical physicist and mathematician, professor emeritus at the University of Oregon.

Why does James A. Isenberg 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 James A. Isenberg?

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 James A. Isenberg.