Mentor of methods and mountains

Twenty-two-year-old Len Margolin knew something was wrong when he saw the Los Alamos Scientific Laboratory security fence. He was on the wrong side of the fence—the inside—without his Lab credentials. Even as a brand-new employee, on the job less than a week, Margolin recognized a major security violation. Then, with lights flashing, the Lab security officers pulled up.

Margolin remembers the incident, which occurred in July 1969, like it was yesterday. “I had finished work and was headed out for a run by the east gate of town, when I spotted a rock cliff leading into the canyon below. So, I decided to climb down.” As he faced the security officers, he realized that his desire to explore had landed him in a difficult situation.

The officers took Margolin into custody. “They called my boss. He wasn’t too happy with me,” Margolin says. Nevertheless, the young physicist wasn’t about to stop climbing, hiking, and exploring. Today, as he celebrates 55 years as a Los Alamos National Laboratory employee, Margolin still spends his time hiking the mountains of northern New Mexico and Colorado. He can say with a smile that it all worked out.

The climb from New Jersey

Margolin graduated from high school in Jersey City, New Jersey, and went on to The Cooper Union in New York to earn dual degrees in physics and math. He continued his education at the University of Michigan, pursuing a PhD in physics during the Vietnam War.

After graduating, “I had to find a useful job or join the Army,” Margolin remembers. In school, he had studied quantum field theory, a mathematical and conceptual framework for particle physics and other areas of theoretical physics, but he was also interested in the early use of computers. 

Computational physicists use high-speed computing to investigate complex physical systems and solve scientific problems requiring large data sets that can only be dealt with through highly automated high-speed processing and storing.

“In the late ’60s, the physics community at large didn’t believe in computational physics,” Margolin says. “They thought the computer was a very good way to solve equations quickly, but they did not view it as a discovery tool.”

But Los Alamos was different. In addition to crisp mountain air, soaring ponderosa pines, and proximity to uncharted places to hike and climb, “people here knew about computational physics and took it seriously,” Margolin explains. “We had some of the fastest computers available, and it was exciting to come to work with people who understood their value.”

Over the years, Margolin has pioneered creating methodologies used in the Lab’s computer modeling and simulation codes. These codes produce three-dimensional models that allow scientists to understand the performance and reliability of the nuclear weapons in the nation’s stockpile. Since 1992, when the United States began a moratorium on underground testing, scientists have used computer simulations instead of conducting live tests of nuclear weapons. Margolin’s work serves a crucial role in national security.

“I’m still here because I enjoy what I do, and I can immodestly say I’m very good at it,” explains Margolin. “I’m working on things right now that I think are very important for science. Think how lucky we are to go to work every day and say, ‘Boy I’m glad I’m here.’”

Margolin’s group leader, Abigail Hunter, says Margolin’s positive attitude is contagious. “Len has had a huge career at the Lab and has been here for so many decades, but the fact that he’s still so excited about and engaged with his technical work makes me feel like I have something to look forward to in my own career,” she says. “Just to have that passion and excitement in your work after 55 years is both rare and inspiring.”

The cliffs of technology

When Margolin first started work at Los Alamos, the Lab had some of the world’s fastest computers, but “fast” was relative.

“When I got here, we were still working on the IBM Stretch machines,” Margolin says. IBM built Stretch, a large-scale (mainframe) computer considered the world’s first supercomputer, to meet the rigorous computing requirements of government laboratories conducting nuclear weapons research. Scientists often needed to carry out more than 100 billion arithmetical operations to evaluate a weapon’s design. Before Stretch, the world’s fastest computers needed six months to solve one of these problems. Stretch was much faster, but remember, that’s fast in late ’60s terms.

“Maybe once a day you would get an answer,” Margolin says. “The rest of the time, you’d wait.”

Back then, data was stored on punched cards, pieces of stiff cardboard with tiny rectangular holes. Computer operators fed the cards by hand into the machine. Margolin remembers bringing long trays of cards, called decks, to the operator and waiting for hard copy printouts of the results. “Some scientists weren’t nice to the operators, and sometimes their card decks would mysteriously be lost,” Margolin recalls with a laugh.

As technology at the Lab evolved, Margolin was always at the forefront of the newest developments. “In 1973, I became the first person at the Lab to get a computer terminal with a screen,” he says. “Harold Agnew, who was the Lab director at the time, stopped by my office to see it. He liked it so much that he bought a bunch.”

Today, Margolin says he’s grateful for the Lab’s high-speed computing power. Even his laptop far exceeds the abilities of those early machines. “Now I hit the button, and my Mac is so fast that I have an answer before my hand comes down—that’s how great things are.”

Margolin appreciates modern technology, but he says he is still learning about the newest technological gamechanger, artificial intelligence or AI. “Many of the younger scientists in my area are focused on AI,” Margolin says. “Although I don’t believe AI will replace human creativity and intuition in the near future, it can be a valuable tool for a multitude of applications at the Lab.”

“When I mentor people,” Margolin continues, “I don’t try to teach them the answer. I ask them, ‘What are the questions?’ When you find the right questions, you’ll find the right answers. One of the questions we should be asking is: ‘How can we use AI to help reach our goals?’”

The heights of history

The evolution of computers is just one of many dramatic changes Margolin has seen during his time at the Laboratory. “When I first came here, Norris Bradbury was still the Laboratory director. In those days, we were about 3,000 people, 16 technical divisions, each with a division leader, and then the Lab director—that was all the management there was.” Today, the Lab has approximately 18,000 employees across countless divisions, groups, teams, programs, and levels of management that didn’t exist when Margolin started his career.

Hunter describes Margolin’s lengthy tenure at Los Alamos as invaluable. “He has seen the Lab change over decades and is one of the few people who understands the history of the decisions that have led to where we are now.” She says she’s glad Margolin has no plans to retire soon, but she worries that when he finally leaves Los Alamos, a wealth of information will leave with him.

Recently, following a visiting scientist’s presentation about coding, Lab employees gathered around Margolin to get his perspective on the talk. Dressed in worn jeans and a plaid shirt, the gray-haired man commanded an audience. “People seek Len out,” says Nathaniel Morgan, one of Margolin’s colleagues. “He knows the background and the history behind the codes we work with every day.” 

Morgan describes Margolin as “an invaluable resource,” saying, “Len has a unique eye from a theoretical physics background.” Morgan adds that Margolin often questions and challenges early-career scientists, pushing them to examine underlying physics, rethink any assumptions, and revisit historical methods. “Everyone tends to circle around Len because he’s the only one left with this indispensable understanding of the past that is so necessary to help us move into the future,” Morgan says.

The mountains of mentorship

Fortunately for Morgan and others, Margolin is passionate about helping graduate students, postdocs, and early-career colleagues. “My idea of mentoring is to do something together—not to lecture someone—to work together and help someone learn,” Margolin says.  “I find enjoyment from watching people learn and grow.”

Scientist Jesse Canfield has benefited from Margolin’s guidance. “Len is a good role model,” Canfield says. “He has worked on everything in weapons physics at the Lab and has a good background and perspective.”

Hunter describes Margolin as generous with his time when it comes to mentoring. “He does a good job pulling in early-career staff and never works in a vacuum,” she says. “He’s very good at working with people and helping his colleagues become technical leaders on their own.”

Margolin himself was mentored by two of the Laboratory’s most distinguished scientists, Bob Thorn and Frank Harlow. “Those two brilliant men made a huge difference for me,” he says. Thorn was the supervisor who hired Margolin, and Harlow was Margolin’s thesis advisor, a Laboratory Fellow, and known by some as the “father of computational fluid dynamics.”

Ascending new peaks

One of the constants throughout Margolin’s 55 years at the Laboratory has been hiking and rock climbing. “I spend all my time doing science, and I think that being creative takes a lot of energy,” he says. “You need to be able to go somewhere where you can really regenerate yourself. The mountains are that for me.”

Margolin’s interest in the outdoors helped him form friendships. He joined the Los Alamos Mountaineers and became one of the more active members of the group. “For many years, I kept my climbing gear in the trunk of my car for whenever someone called to say, ‘Let’s go climbing tonight,’” Margolin says. Over the years, he discovered and named numerous climbing routes. He served as the club’s first search and rescue director and helped establish nearby White Rock Canyon as a key place for top rope climbing, a form of rock climbing where an anchor holds the climbing rope from above.

Margolin also spent many years climbing the Brazos Cliffs near Tierra Amarilla in northern New Mexico. The approximately 3,000-foot-high escarpment offered endless climbing opportunities. Margolin and several of his Lab coworkers spent numerous weekends exploring the challenging cliffs.

In 1975, Margolin had the chance to explore a new set of mountains when the Laboratory sent him and three geologists to take measurements at Mount Baker, a volcano in Washington state that had just become active. Margolin recalls that their expedition was prolonged by a 5-foot snowfall and whiteout conditions that stranded them near the top of the mountain for an extra two days. Despite (or perhaps because of) those challenges, his love of the mountains continued to climb.

After ascending many of New Mexico’s highest peaks, Margolin began summiting “fourteeners,” mountain peaks with elevations of at least 14,000 feet above sea level. Although New Mexico has no fourteeners, there are more than 50 such peaks in Colorado and 1in Washington State. He climbed all of those and then learned that there were about a dozen more fourteeners in California.

“California is also the home of Los Alamos’ sister laboratory, Lawrence Livermore National Laboratory,” says Margolin. “So, in 1985, I moved there to work for Livermore, climbed all those fourteeners, and then I came back to Los Alamos.” Because the University of California operated both labs at the time, Margolin’s employment at Livermore counts toward his 55-year service anniversary. “At Los Alamos, we joke about competing with Livermore,” he says, “but the truth is we are all working together toward the same goal of national security. When you are inside the buildings, it’s exactly the same.”

It was what rose just beyond some of those  buildings—the mountains of northern New Mexico—that drew Margolin back to Los Alamos only five years after he left. He has lived in New Mexico, hiking those mountains, ever since. Margolin admits that at 77 years old, climbing mountains is a bit harder than it once was, but says, “I have good health and I can still hike with the best of them, so I figure I’m really lucky.”

Margolin’s other interests are evident in his favorite Star Trek episode (“Darmok” from Star Trek: the Next Generation), his favorite movie (I, Robot), and his favorite author and philosopher (Isaac Asimov). He enjoys taking photographs while hiking and is considering writing a science fiction novel… if he ever decides to retire.

Margolin says that when he looks back at his career, he can’t point to specific accomplishments. “There have been some very significant things I’ve worked on, but no one thing stands out.” Then again, Margolin is still climbing—both literally and through his scientific research. “Through the years, I’ve had many colleagues and students, and together we’ve made many important contributions to the field of computational physics,” he says. “I still have important work to do.” ★

Read about another Los Alamos mountaineer.