Paul Steinhardt

Paul Joseph Steinhardt (born December 25, 1952) is an American theoretical physicist. He studies the universe and the nature of matter. He is the Albert Einstein Professor in Science at Princeton University. He teaches in both the Physics and Astrophysical Sciences departments.

Steinhardt is known for creating new ideas about how the universe began and how it might continue. He also discovered a special kind of material called quasicrystals. People once thought these only existed in labs. He found natural examples in old museum samples and in meteorites from far eastern Russia.

In addition to his research, Steinhardt has written two popular books. Endless Universe: Beyond the Big Bang (2007), which he co-authored with Neil Turok, talks about new theories of the universe. His second book, The Second Kind of Impossible: The Extraordinary Quest for a New Form of Matter (2019), tells how he and his student Dov Levine imagined quasicrystals and searched for them in meteorites.

Education and career

Paul Steinhardt was born in 1952 in Miami, Florida. He went to Coral Gables Senior High School and also took classes at a nearby university. He earned his Bachelor of Science in physics from the California Institute of Technology in 1974 and his Ph.D. in physics from Harvard University in 1978. After that, he worked at the Harvard Society of Fellows until 1981. He then joined the faculty at the University of Pennsylvania, where he became a professor. Since 1998, he has been a professor at Princeton University, where he also helped start the Princeton Center for Theoretical Science and led it from 2007 to 2019.

Research

Inflationary cosmology

In the early 1980s, Paul Steinhardt helped create important ideas about how the universe began. In 1982, Steinhardt worked with Andreas Albrecht and Andrei Linde to develop the first models of inflationary cosmology. These models explain how the universe expanded quickly to look smooth and flat. They discovered a "slow-roll" effect that helped inflation last long enough to match what we see today.

Steinhardt also studied how tiny changes during inflation could create the seeds for galaxies. He later looked into the idea of eternal inflation, which suggests that inflation might continue forever, leading to a multiverse — many different universes. However, Steinhardt worried that this idea makes it hard to predict anything about our universe.

Bouncing and cyclic cosmology

Because of some problems with inflationary theory, Steinhardt created new models. These models replace the big bang with a "bounce." In these ideas, the universe moves smoothly from shrinking to expanding, avoiding issues like the multiverse. These bouncing models suggest that the universe goes through cycles of expanding and contracting.

Dark energy and dark matter

Steinhardt has also studied dark energy and dark matter. In the 1990s, he showed that there must be dark energy making the universe expand faster. He suggested an idea called quintessence, a type of dark energy that changes over time, instead of a constant cosmological constant. He also worked on models of self-interacting dark matter to explain things that regular models cannot.

Quasicrystals

In 1983, Steinhardt and Dov Levine introduced the idea of quasicrystals — a new type of solid with a special atomic structure that was thought to be impossible. Their idea was proven when Dan Shechtman found a real quasicrystal in 1984. Steinhardt's team later found natural quasicrystals in meteorites and even in materials from the first atomic bomb test.

Photonics and hyperuniformity

Steinhardt's work also included creating new materials with special light properties. He helped design photonic quasicrystals that can control light in certain ways and discovered hyperuniform disordered solids, which can act like semiconductors for light. These materials could be useful for communications and energy harvesting.

Amorphous solids

Steinhardt studied disordered solids like glasses and amorphous metals. He made early computer models of these materials and looked at their structural and electronic properties, helping us understand how atoms arrange in these substances.

Honors and awards

Paul Steinhardt has received many awards for his important work in science. In 1986, he became a Fellow of the American Physical Society. In 1998, he received the P.A.M. Dirac Medal together with Alan Guth and Andrei Linde for their work on ideas about the universe. In 2010, he was given the Oliver E. Buckley Condensed Matter Prize for his studies of special crystal shapes called quasicrystals. He also received the John Scott Award in 2012 and the Niels Bohr Institute Medal of Honour in 2020.