Inside the South London workspace of Doppel, a startup specializing in wearable technology, CEO Fotini Markopoulou, a former quantum physicist, contemplates the most effective way to create an off-switch for their new device. Nestled between a Swedish café and a wig-making shop, the office buzzes with creativity as Markopoulou and her three co-founders gather around a chaotic table, brainstorming the features of their upcoming product, set to launch in October. This sophisticated wrist-worn device emits a steady, rhythmic pulse akin to a heartbeat, designed to help users manage their emotions and maintain mental clarity.

Markopoulou, spinning in her chair, expresses her preference for a “smothering” gesture to deactivate the device, as it feels intuitive and suggests the device has a life of its own. “You could always murder it,” quips Jack Hooper, the commercial director. Andreas Bilicki, the tech lead, suggests alternatives like “choke” or “asphyxiate,” while the team playfully tosses around ideas: “throttle”; “go to sleep”; or “turn your Doppel off, like covering a parrot’s cage with a blanket.”

Markopoulou, who is 45, observes the banter with a subtle smile. She possesses striking features and heavy-lidded eyes that convey a sense of guarded intelligence. Dressed in a green sweater and a blue scarf adorned with fish-like scales, she radiates a casual confidence that belies the 20-year age gap between her and her team. Although she resides in Oxford, she often crashes on the couch of design director Nell Bennett when in London.

After their meeting, Markopoulou and I descend to grab coffee, where her enthusiasm for crafting products that people will use is palpable. “The satisfaction of accomplishing something tangible, whether creating or selling, is immensely rewarding,” she shares. “I enjoy tackling real-world challenges, such as persuading others that Doppel is a worthwhile innovation or negotiating with an accountant.”

Markopoulou’s transition from the theoretical realm of physics, where she once thrived, raises questions about her current pursuits. One of the most innovative and original theoretical physicists alive, she was instrumental in the development of quantum gravity at the Perimeter Institute for Theoretical Physics in Waterloo, Canada. This branch of physics seeks to bridge the divide between general relativity, introduced by Einstein, and quantum mechanics.

Quantum theory elucidates the chaotic interactions of fundamental particles governing the universe's forces, while general relativity elegantly describes gravity as a consequence of the curvature of space-time caused by mass. However, attempts to reconcile the two have led to perplexing mathematical contradictions, akin to a soccer player and a tennis player trying to compete without understanding each other’s rules.

After years of dedicated research, Markopoulou co-developed a groundbreaking concept dubbed “quantum graphity.” This model suggests that the universe operates on an incredibly small scale, where space and its laws evolve from a network of interconnected points, much like a soufflé rising in an oven.

“Fotini is exceptionally original, perhaps to a fault,” remarks Lee Smolin, a fellow Perimeter founder and Markopoulou’s ex-husband. “While most scientists build upon established ideas, she exclusively pursues her unique concepts.”

Sipping her latte, Markopoulou reflects on her past in theoretical physics. “It felt like living in a monastery, where normal human needs shouldn’t distract from the quest to comprehend the universe's origins,” she states. “In my previous mindset, leaving felt like a moral failure; it indicated a loss of devotion.” Yet, she acknowledges, “It wasn’t so much a loss of faith, but rather a personal transformation.”

Now, five years since departing from physics, she continues to grapple with this change. Markopoulou reevaluated her role at Perimeter when the new director, Neil Turok, criticized her work as overly speculative, leading to her exit. However, her discomfort with the academic environment ran deeper.

Working in such an ethereal field, she felt increasingly detached from her personal life. “Many friends in their late 40s still lack a stable home or family, as long as they have a place to think,” she reflects with a wry smile. “I obviously failed that test. For many, that lifestyle makes sense; I get it 80 percent of the time, but it’s the remaining 20 percent that complicates matters.”

Doppel embodies the aspects of her prior work in physics that she missed. The company is rooted in psychophysiology, exploring the profound connections between the mind, body, and environment. Yet, acknowledging that our sense of self intertwines with the world can be daunting, Markopoulou admits. The fear of this interconnectedness and the desire to understand it initially drew her to physics.

“I appreciated how science provided a degree of detachment from those fears,” she explains. “Between the physical truths and physics theories lies humanity. Yet, removing the person is the essence of scientific training.” She pauses, contemplating, “But this may or may not be feasible.”

Growing up in Athens, Greece, Markopoulou appeared as a typical teenager with permed hair and a love for Clint Eastwood films. Yet, she was always captivated by profound truths. Sometimes, on her way home from school, she would stop by Greek Orthodox churches to lie on the pews and contemplate the starry and angelic murals adorning the domes. At 15, she discovered a book titled Starseekers in the British Council library, igniting an obsession with cosmology. “I became completely engrossed in that book,” she recalls, persuading her mother, Maria, to buy her an Atari computer to translate it into Greek.

Markopoulou lived with her mother in a small studio, where Maria, a figurative sculptor, navigated her own tumultuous life, raising Markopoulou as a single mother. “Her perspective was unique; she believed sleeping was akin to dying,” Markopoulou shares. “I realized I couldn’t rely on her view of reality.”

The subjectivity of artistic merit frustrated Markopoulou. “One thing I loathed about the art world was the arbitrariness of decision-making,” she states. “People could dismiss Picasso simply based on personal whims, which I found infuriating and political.”

Markopoulou’s education in Greece was lackluster, prompting her to seek private classes her final year of high school. By chance, she stumbled into an A-level program, ultimately enrolling in Queen Mary’s University in London. Despite failing her A-levels — “The first time I entered a lab was during the exam, and I answered half the questions in Greek” — her tutor secured her a place at her top-choice university, renowned for its welcoming atmosphere and excellent particle physicists.

Financial constraints limited her social life, leading Markopoulou to organize birthday parties at McDonald’s for extra income. Nevertheless, she cherished her university experience, bonding with fellow students over lectures and occasionally attending their professors’ amateur rock performances. She soon realized, however, that some topics were better left unasked; she sought deeper understanding beyond established norms.

Toward the end of her undergraduate studies, a friend suggested she attend a quantum gravity lecture by Chris Isham, a mathematical physicist with a penchant for mysticism. Isham’s ability to connect the technicalities of science with human inquiries left a lasting impression on Markopoulou. “Physics can resemble plumbing — you fix things with equations and tools, gaining respect for your expertise,” she explains. “But the profound questions, those are what initially inspire most of us to pursue this field.”

Under Isham’s mentorship, Markopoulou delved into quantum gravity. Her Ph.D. project involved exploring the movement of dust particles to develop a new approach to disentangling time from spatial dimensions. This inquiry stemmed from Einstein’s revolutionary insight that time is intricately linked to space, capable of distortion by mass and movement.

However, Einstein's conception of time clashes with quantum theory, where phenomena like particles existing in two places simultaneously challenge traditional notions. It became apparent to Markopoulou that reconciling these disparate views might hinge on a closer examination of space itself. Following her initial research on dust modeling, she began working with spin networks — geometric models aiding physicists in describing quantum interactions.

Her innovative approach caught the attention of Smolin, who was visiting from Penn State. Together, they collaborated on a paper about causal sets and she later joined him in Pennsylvania, where they married in 1999.

At Penn State, Markopoulou found herself among brilliant minds in the burgeoning field of non-string quantum gravity. “A sense of collaboration and urgency prevailed; it felt like breakthroughs were possible at any moment,” she recalls. Contrarily, she found string theory to be rigid and competitive.

While many contemporaries concluded that time is an illusion at a fundamental level, Markopoulou approached the subject differently, prioritizing time and viewing space as an outcome or trace of temporal events. “I lean toward maintaining a traditional understanding of time, which presents both challenges and opportunities,” she notes.

In the early 2000s, rumors circulated about a substantial donation for an institute focused on foundational physics. Markopoulou and Smolin were approached by Howard Burton, who acted as an intermediary for the benefactor, Mike Lazaridis, founder of Blackberry. After a clandestine visit to Canada, they were persuaded to establish the Perimeter Institute.

By the time the institute launched, Markopoulou and Smolin had separated but remained amicable. The founding faculty worked diligently in a former restaurant, hoping to foster a collaborative and innovative research environment devoid of traditional hierarchies.

While Markopoulou was not an authoritative leader, she was influential, as evidenced by a hiking trip where her suggestions guided the group’s direction. At Perimeter, she thrived when learning and experimentation flourished, leading to playful and inventive work.

Markopoulou, alongside collaborators Simone Severini and Tomasz Konopka, developed the concept of quantum graphity, viewing the universe as a network that evolves over time. Her model, inspired by the principle of emergence, sought to visualize the emergence of spacetime structure during the universe's birth.

As her reputation grew, Markopoulou became a public representative for Perimeter, relishing the opportunity to inspire the next generation of female scientists. However, she faced skepticism regarding her more radical theories, which were sometimes dismissed as “creative.”

Markopoulou’s unconventional approach led to discontent. Each problem solved seemed to spawn new challenges, and the academic environment began to feel restrictive. “At times, it felt like I was performing for an audience, sharing profound concepts that others perceived as entertainment,” she reflects.

In 2008, Turok took the helm at Perimeter, shifting its focus toward other physics areas. By 2009, Markopoulou’s personal life was also undergoing significant changes. After meeting Doyne Farmer at a conference, the two quickly fell in love and restructured their lives together. Their son, Maris, was born in 2010, shortly before her mother Maria passed away.

Despite her ongoing passion for deep inquiry, Markopoulou felt her colleagues’ judgments regarding her work increasingly subjective. “In a realm of certainty, life becomes mundane,” she observes. “Conversely, leaping without a parachute can lead to folly.”

As Perimeter expanded, Turok sought to formalize its structure, prompting Markopoulou to apply for tenure. However, her independent research trajectory raised doubts among the leadership, resulting in her tenure denial.

Disappointed by the shift away from the institute’s initial collaborative spirit, Markopoulou ultimately departed from Perimeter in late 2011.

In March, I visit Markopoulou at her home near Oxford, surrounded by tranquil nature. The space, once a grocery store run by poet Robert Graves’ wife, now reflects Markopoulou’s love for theater and her Greek heritage. “Theater allows you to shift reality and participate actively in a different perspective,” she explains.

Settling into a cozy armchair, she acknowledges the transformative impact of her mother’s passing on her creative journey. “I refrained from engaging with art while she was alive, but now I recognize that crafting and creating are intrinsic to my identity.”

Markopoulou draws parallels between physics and sculpture, emphasizing the need to understand the essence of a concept before crafting it into a cohesive theory. “I never aimed to single-handedly solve quantum gravity, but I always believed in its possibility,” she adds, pondering its feasibility in the future.

Throughout her transition, Farmer has been a steadfast support. “I derive much of my identity from my work, so navigating this change was challenging,” she admits. “However, I was fortunate to have a nurturing environment.”

Farmer, a notable physicist, has made significant contributions to the field of econophysics. When he accepted a position at Oxford in 2011, Markopoulou began exploring opportunities in industrial design. A conversation with musician Brian Eno led her to pursue a master's program in Innovation Design Engineering at the Royal College of Arts and Imperial College in London, where she thrived.

The program included unique exercises, such as devising strategies to escape a zombie horde. Though initially challenging to transition from cosmic origins to mundane product design, Markopoulou found joy in creating tangible objects and formed the team behind Doppel during a sailing trip.

Doppel was inspired by concepts of interoception, which explores how humans perceive internal bodily states. Markopoulou believes our sense of self arises from the interplay between our brains and bodies, challenging the notion that cognition is solely mental.

Looking back, she views her work at Doppel as a logical evolution from her physics background. “Physics is a human endeavor, shaped by our senses,” she asserts. “Shouldn’t our understanding of the universe include those senses?”

Markopoulou recognizes that many scientific disputes stem from differing metaphysical beliefs. Her conviction in the reality of time reflects a moral standpoint. “Believing in the reality of time fosters a sense of responsibility,” she asserts.

This understanding of time has empowered Markopoulou to reinvent herself, shifting from a physicist to a designer and entrepreneur. “I commit fully to whatever I do; when I switched gears, I did so entirely,” she states. “While the mind wanders through time and fantasy, the body exists in the present.”

Markopoulou believes her journey with Doppel is just the beginning. “Every endeavor requires context; academia and business have distinct rules. I’m still navigating and discovering my place within them,” she concludes.

Sally Davies is a writer based in London. She was formerly an associate editor at Nautilus and the technology and innovation correspondent for the Financial Times. She is now a senior editor at Aeon.