Garrett Lisi: E8 Theory, Surfing & Physics Interview

Garrett Lisi is a theoretical physicist and Physics Forums member who developed the E8 Theory, a proposed geometric framework for unifying particle physics using the E8 Lie group. He splits his time between physics research in Maui and surfing, and in 2007 his E8 Theory paper drew both mainstream media attention and sharp criticism from other physicists.

Key Takeaways

• Garrett Lisi published his E8 Theory paper in 2007, proposing that Standard Model fermions and forces can be described using the mathematics of the E8 Lie group.
• The E8 Lie group itself was discovered by mathematician Wilhelm Killing roughly 120 years before Lisi’s interview.
• Lisi’s 2015 paper, “Lie Group Cosmology,” describes fermionic degrees of freedom geometrically by treating spacetime as embedded within a deforming Lie group.
• The Pacific Science Institute, which Lisi directs, had been operating for a year at the time of this interview and had hosted about 60 visiting scientists, students, and friends in Maui.
• Physicists Lubos Motl and Jacques Distler publicly criticized Lisi’s work following the 2007 paper’s release.
• Lisi grew up in Rancho Santa Fe, San Diego, and later attended boarding school in Santa Barbara.

What was Garrett Lisi’s childhood like in San Diego?

Garrett Lisi grew up in Rancho Santa Fe, a part of San Diego he describes as idyllic. He had a fairly normal, happy childhood as an introverted kid who spent much of his time reading, building with LEGO, riding his bike, and later programming computers after his father brought one home.

Lisi says most of the best things he learned came from outside of school, such as playing games with friends. He later attended boarding school in Santa Barbara, where he says academic life became more intense.

What drew Garrett Lisi to physics?

Lisi says surfing is extremely fun but cannot be all one does. In high school he had the usual adolescent questions about the nature of the universe and humanity’s place in it.

His reading led him from philosophy into popular physics, where he encountered the idea that mathematics is the underlying language of how the universe operates. Because he had always been strong at math, discovering that it was the key to understanding physics was thrilling, and he says he has been hooked ever since.

What is Garrett Lisi’s life like in Maui today?

Garrett Lisi says living in Maui is fantastic, with warm, beautiful water and abundant waves and wind that make the island a natural playground for him. He particularly enjoys hosting friends and fellow scientists and introducing them to the island.

Have adventure sports shaped Garrett Lisi’s approach to physics?

Lisi suspects that adventure sports have influenced his scientific thinking by giving him greater mental flexibility when tackling difficult problems. He describes hitting mental walls while working on tough problems, where nothing he tries seems to work.

By throwing himself into an intense, unrelated physical experience for a couple of hours, Lisi says he often returns with a fresh perspective and finds new approaches he might not have discovered by continuing along the same lines of thought.

How does Garrett Lisi balance physics with the rest of his life?

Lisi describes the balance as complicated. Playing outside, spending time with people, and working on other projects keeps him happy enough to devote most of his intellectual energy to physics, which he finds rewarding but much harder than his other pursuits. He says he doesn’t feel competition in physics very strongly.

Lisi believes many other theoretical physicists are searching along the wrong paths, arguing that string theorists should have abandoned string theory and supersymmetry decades ago in favor of other models. He notes that even within the loop quantum gravity community, only a handful of researchers have pursued geometric descriptions of particles and the Standard Model.

Lisi points to physicist Ali Chamseddine’s paper (arxiv.org/abs/1602.02295) as an occasional sign of progress in this direction, though he says such work still lags roughly a decade behind his own. He acknowledges this view may sound arrogant and admits it is also possible he is completely wrong.

How did publishing the E8 Theory affect Garrett Lisi’s career?

The E8 Lie group, a mathematical structure at the center of Lisi’s work, was discovered by mathematician Wilhelm Killing roughly 120 years before this interview. Lisi published his own E8 Theory paper in 2007, proposing that the mathematics of E8 could describe fundamental particles and forces.

The attention following the 2007 paper was, in Lisi’s words, a mixed bag. He was invited to unusual and interesting opportunities including heliskiing and appearing in a television show, which he found fun but distracting. He also received considerable criticism, including what he describes as mean-spirited attempts to discredit him and his work from physicists Lubos Motl and Jacques Distler, which he says was both annoying and professionally harmful.

Because Lisi had largely worked alone along a research direction outside the mainstream, he says he lacked community support, and many physicists judged his work based on the surrounding hype and criticism rather than its content. He says he doesn’t think that judgment will prove accurate, though he allows that it might. His life has since returned to what he calls a normal cycle of surfing and physics.

What is Garrett Lisi currently working on with E8?

In 2007, Lisi showed that the mathematical structure of fermionic spinors, particles such as electrons and quarks, can be described algebraically using E8 and other exceptional Lie algebras. More recently, in his “Lie Group Cosmology” paper (arxiv.org/abs/1506.08073), Lisi describes how to understand anti-commuting fermionic degrees of freedom geometrically within this framework.

In this approach, spacetime is embedded within a deforming Lie group, and the physical anti-commuting Grassmann fields, mathematical objects used to represent fermions, appear as 1-form fields orthogonal to spacetime. Lisi says this piece of the puzzle has made him feel much better about a geometric description of Standard Model fermions.

Lisi identifies the main remaining problem as how triality, a symmetry relating different mathematical representations, connects the three known fermion generations and produces their masses. For several months before this interview, he had been working with octonions and split-octonions, number systems related to triality, calling the work very enjoyable.

Who does Garrett Lisi want to collaborate with on E8?

Lisi says he has had productive conversations with several mathematicians and a few established physicists about his E8 work. What he would most like, however, is to collaborate with students and postdoctoral researchers interested in the same research directions.

He describes the geometric description of fermions as a rich area that has been difficult for him to fully explore alone, and says bringing younger researchers into the topic would likely be productive.

What is the Pacific Science Institute?

The Pacific Science Institute (pacificscienceinstitute.org), which Lisi directs, had been open and operating for a year at the time of this interview, with a steady stream of visiting scientists, students, and friends. About 60 people had come to Maui and stayed in the institute’s guest cabins during that period, enjoying the island and its atmosphere.

What other scientific developments interest Garrett Lisi?

Lisi says there has been fantastic recent progress across experimental physics and other sciences. He cites AlphaGo’s success as a major step forward for artificial intelligence (AI), and points to CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats), a gene-editing technique, as having enormous potential in bioengineering.

Lisi also mentions the detection of gravitational waves by LIGO (Laser Interferometer Gravitational-Wave Observatory) as a great achievement. In particle physics, he notes that the Large Hadron Collider (LHC) had seen an intriguing 750 GeV (gigaelectronvolt) bump at one point, and that important developments regarding neutrinos continue to occur.

What are Garrett Lisi’s near-term plans?

Lisi says his near-term plans involve mostly more physics, surfing, and kitesurfing. He has also been enjoying his role as director of the Pacific Science Institute, where he has hosted old and new friends visiting Maui for conversations and outings around the island. He says he may continue in this role for a while and perhaps expand it to other locations.

Where can readers follow Garrett Lisi’s work?

Garrett Lisi shares his favorite books, movies, and musicians on Facebook, where readers can friend or follow him. To learn more about his E8 work, visit his homepage at sifter.org/~aglisi.

Frequently Asked Questions

What is Garrett Lisi’s E8 Theory?

Garrett Lisi’s E8 Theory, published in 2007, proposes that the mathematics of the E8 Lie group can describe the Standard Model’s particles and forces geometrically. Lisi has continued developing this idea, including in a 2015 paper on Lie Group Cosmology addressing fermionic degrees of freedom.

Did Garrett Lisi face criticism for his E8 Theory?

Yes. Lisi says he received considerable criticism after publishing his 2007 paper, including what he describes as mean-spirited attempts to discredit him and his work from physicists Lubos Motl and Jacques Distler. He says this criticism was both annoying and professionally harmful.

Where does Garrett Lisi live and work?

Garrett Lisi lives in Maui, Hawaii, where he directs the Pacific Science Institute. He divides his time between physics research, surfing, and kitesurfing, and hosts visiting scientists and students at the institute.

What is the Pacific Science Institute’s connection to Garrett Lisi?

Garrett Lisi directs the Pacific Science Institute in Maui, which had been operating for a year at the time of this interview. It had hosted roughly 60 visiting scientists, students, and friends in its guest cabins.

What is Garrett Lisi currently researching?

Lisi is currently working on how triality relates the three known fermion generations and produces their masses, using octonions and split-octonions in relation to this symmetry. This builds on his earlier work describing fermionic spinors algebraically through E8 and other exceptional Lie algebras.

Who discovered the E8 Lie group?

The E8 Lie group was discovered by mathematician Wilhelm Killing roughly 120 years before this interview took place. Garrett Lisi later used this mathematical structure as the basis for his 2007 E8 Theory paper on particle physics.