In 2014, however, Hagar had what could mundanely be described as a midlife crisis.

He prefers to describe it more colorfully, as a “heresy.” He’d come to an uncomfortable realization, he says: “Physics is stuck. We need a leap that’s beyond our reach.”

Hagar believes—as do others—that in the absence of the kind of tremendous technological breakthrough that comes perhaps once or twice in a millennium, philosophers of physics have very little to contribute, though exploratory physicists can certainly carry on their work.

In short, Hagar had reached a standstill: “I was 45 years old and I had 20 more years of my career in front of me. Now what?”

He found the answer by turning to entirely new fields. Though he lacks a formal degree in medicine or biology, he started to study how cancers grow. More precisely he looked at the biophysical modeling of solid tumors and explored the intersection of kinesiology and cancer biology. In the process, he founded his own company, Cellsor LLC, and patented a method for optimizing a woman’s mammogram screening schedule based on her level of aerobic fitness. He is now also studying other degenerative conditions like Alzheimer’s and liver disease.

Hagar began his new work by thinking about breast tumors and mammography. He picked this subject because every year, just before he and his family left for vacation, his wife had an anxiety-inducing mammogram. Fortunately, the mammograms never showed any tumors. But he wondered about their timing.

“I found that mammogram schedules around the world seemed to depend more on culture and geography than biology,” he says. He learned that for the majority of women, mammograms come either too early or too late, because tumors grow at different rates in different women.

So, Hagar reasoned, “if we can know the personal growth rate of a woman’s tumor, we can make more rational decisions about when to do a mammogram and thus save lives.”

Decades of research has showed that aerobic fitness slows the growth of tumors. Relying on this insight, Hagar and his graduate student, Luma Melo, trained mice to run on exercise wheels. He found that when he injected aerobically fit mice with tumors, their cancers grew more slowly.

He then tested the aerobic fitness of a small group of women who had already been diagnosed with breast cancer and compared it to their documented tumor growth rates. Based on his research, he now has a U.S. patent for a simple method of assessing aerobic fitness that doctors could use to determine how often women should go through routine mammogram screening. He has pending patent applications in Canada, Australia, Brazil, and the EU. Hagar also believes that aerobic fitness could one day be part of cancer treatment and prevention, not just diagnosis.

As he did his research, it turned out to be fortunate that there is a second class of thinkers whom Hagar admires as much as heretics. “I like underdogs,” he explains. “I’m one. I jumped into this new field and suddenly everybody was asking me, ‘Who are you?’ ‘What are your credentials?’ ‘Why are you doing this?’” In one year alone, he applied for seven National Institutes of Health grants and was turned down every time. He now is applying for the eighth, for his own company, to do a clinical trial in Israel. “It took blood, sweat, and tears to get every data point, to get patients, to get funding,” he says.

History shows that underdogs and heretics are often proved right. The reason has partly to do with their persistence, Hagar explains. “People like me come through the back door. Or if you close the back door, we come through the window. If you close the window, we come through the floor.” Their persistence results in part from necessity, because science has a structural problem. As Hagar says, “the system tends to grant resources mostly to established scientists,” not to newcomers and upstarts like him.

In the end then, Hagar’s understanding of the cultural and historical context of science underlies his new research direction. “As a philosopher of science,” he says, “I’m really a sort of anthropologist. I’m cognizant of the errors and pitfalls of the scientific process. I understand that science has defects. It’s done by human beings who have egos. But it’s the only way we can observe and understand nature.”

Today, he says, “the Department of the History and Philosophy of Science and Medicine in the College has tasked itself with making better scientists. It takes a campus to make a good scientist. Apart from biology courses and labs, students need to learn about themselves as human beings and about other human beings. They need to learn about methodology and research methods to be good scientists.” And Hagar has a lot to teach them.