Dr. Lawrence Fleinhardt is a professor of physics at CalSci (a university based on Caltech and located in Los Angeles in the Numb3rs universe) and best friend and colleague of Charlie Eppes. He is portrayed as a brilliant theoretical physicist and cosmologist, who researches supersymmetry, string theory, 11-dimensional supergravity theory, doubly-special relativity, black holes, and gravitational waves, using LIGO to check predictions on quantum corrections. He may have even found a way to express Calabi-Yau manifolds in a way that goes beyond a non-vanishing harmonic spinor and, independent of Charlie, published a work of genius entitled Zero Point Energy and Quantum Cosmology, which could provide insight into the cosmological constant problem (episode 3x4,The Mole).
Larry has always been fascinated with the stars. He had his first telescope at age three, was the president of the rocket club in the fifth grade, and worked as a docent at his local planetarium while in junior high school. Fleinhardt also had an addiction with card counting in his youth, which he feels ashamed about and has compared his discomfort during field research at a casino as being at the event horizon of a black hole; this was discussed in Double Down, an episode that focused on a gambling ring. He wanted to prove the power of mathematics. The only thing he remembers of his mother is her warm smile and tweezed eyebrows. He rarely has spoken of his father, a painter who wished his son had seen the world the way he did and was disappointed by his son's path; Fleinhardt expressed his sorrow with a memory he does not gladly inhabit, stating it is a father's folly to impose their will on their son. Consequently, Larry has an exhaustive knowledge of art and attempted a career as a painter, but failed as he was required by his father to study the great works of the masters before he could create an original work.
Larry frequently wears casual patterned shirts and drove a 1944 Volvo until he acquired a 1931 black Model A Ford that he cherishes. Fleinhardt owned a personally restored 1877 Victorian home which he sold in "Bones of Contention". The character evinces a distaste for number theory and cell phones, but enjoys hiking. Also akin to Feynman, he percusses, but never for pleasure — he drums away problems. Both he and Charlie are members of the North American Sundial Society, and they have worked together on various contests for the physics department, including a paper airplane contest. Larry has a Zen rock garden and has constructed his own Heron's fountain. He likes to "ponder the koi pond" in front of Charlie's home, with each fish named by Eppes.
After the "untwinable" event of having "carnal" relations with Laurel Wilson ("Sabotage"), a philosophy professor with whom he regularly took hikes, Larry begins to wonder about his life choices, missed (romantic) opportunities, and the impact of children (or wormholes in Larry's view) on people's lives. Larry has additionally noted how demanding physics can be on his social life (that is nigh-nonexistent as a result of his work) and, along with Charlie, understands Einstein's feelings that one can either do physics or have a family, but not both. Meanwhile, he has realized his affections for Megan, and describes to his confused friends, the Eppes family, that they are closer to understanding the mystery of gamma ray bursts than his feelings in this matter. Thus, Larry begins a relationship with Agent Megan Reeves. When he finds out she is kidnapped in "Two Daughters", Larry's emotions overcome him. Megan claims to like him for his unpredictability. Larry shortly thereafter becomes distracted by his relationship with Megan, and desires more structure. Charlie has not seen such an emotional uncertainty with Larry as when he speaks of her and, as Larry has commented himself, his previously unstructured relationship with Megan made baryogenesis look neat. In "Long Shot" (episode 3x06) they create a schedule for dinner and a movie every other Friday, lunch on Wednesdays, and a monthly wild card that Megan can use at her discretion. Though, he has recently commented that his relationship with Megan has made him less concentrated on his work.
After selling his home, Fleinhardt has for some time since been living as somewhat of a vagabond, finding shelter in his office, his car, hotels and friends' places, and often sleeping on couches or in CalSci's steam tunnels. Larry claims he didn't want to inconvenience Charlie and thought that sharing one bathroom would be problematic, and further did not want to move in with Megan and ruin something "before it even began." He also claims to believe it allows him to focus on the sublime rather than the mundane, as well as gravity. Alan has commented on his state during one of their chess games, providing the same advice he has dispensed to all geniuses he knows: "Don't be an idiot." Contrarily, Megan finds his situation oddly attractive. However, he "rethought the pursuit of a purely intellectual endeavor." Wanting less complexity and more structure in his life, as well as time to be with Megan, Larry states that he has decided to buy a condo. However, life has never been simple for Larry, and Alan has said that simplicity may be impossible for him, so he must deal with structured complexity.
In the episode "Brutus", it is revealed that Larry's divestment of his personal property was in anticipation of being selected as a payload specialist on the International Space Station. His work on the cosmic microwave background has some relevance to the NSA's satellite signals technology and he was contacted by this agency last September to serve as an alternate for the recently detained Professor Johannes Igby, a rival physicist who created the now proven (though initially contested by Larry) Igby's Law to redefine the gravitational flux motivated by sound wave propagation in Bose-Einstein condensates and a candidate on the short list for the National Medal of Science award. Larry is distressed when he first hears of Igby's success from Charlie and sees the vindication in his Quarterly Review of Cosmology magazine, but soon recognizes, to his own excitement in a seemingly conflicting manner, that he is his replacement for the space mission, causing Charlie to believe he is in shock. Megan seems to be the only one who has some idea of this situation that explains his unorthodox living style and prior mystifying absences (to go to Houston), though his friends had thought that these elements were just part of Larry's quirks. Charlie is in disbelief over the matter and is distraught at the potential of a temporary loss of his friend, even worrying about Larry's safety as he boards the next shuttle to the ISS for a six-month stay 250 miles above Earth; even Larry is mindful of the risk involved in sitting atop 2 million liters of combusted liquid hydrogen and oxygen. He remands his few prized possessions, including a miniature model of his classic car, a stash of jazz recordings, a Newton Lacy Pierce Prize in Astronomy by the American Astronomical Society he received long ago, a Science Journal International diploma, and an old t-shirt he wore on the first day he posited causal solutions to ultra-hyperbolic wave equations and, more memorably, when he vanquished Professor Muskrave at the CalSci Texas Hold'em Tournament, to his closest friend, Charlie. The reason he provides for not informing his friends of the big news is that he considered it a long shot and said it is only with the good fortune that Igby's new responsibilities have prevented him (Igby) from procuring his place on the shuttle, so that he may realize his dream of space exploration. On the other hand, Larry states he will miss Megan and she responds in kind by being supportive and intensifying their relationship before his departure. They even start sharing each others' predilections. In "Killer Chat", Larry's fulfillment of his dream is called into question as a rival in Massachusetts (at MIT) told NASA that he had been living in the steam tunnels. Larry himself says that he is a bird with his wings "clipped" and a "steam tunnel freak," and Megan says he is a "star collapsing in on itself." When Charlie gets him back on the mission, stating to a NASA official that he is "eccentric but brilliant," Larry is grateful. Buzz Aldrin sees him off and Larry's friends watch his launch over a glass of milk due to Larry's propensity for white foods, with Charlie being particularly emotional.
In "The Art of Reckoning", Fleinhardt returns from the space station, landing at Edwards Air Force Base. He was away for four months and twelve days and lost six percent of his bone density due to microgravity effects. Millie states it is "one small step for Fleinhardt and one giant leap for CalSci." While Charlie is ecstatic to see his friend and inquires about the awe in celestial phenomena and his LISA data, Larry is detached and not ready for complex social interactions such as a CalSci welcoming party, though he wants to have dinner with him. He finds the concept of a confined space intolerable and stays at the beach. Eppes is concerned and just wants his buddy back. Larry wants to feel less important and takes great stride in the "fragility and beauty" of Earth; he possesses a condescending view of mankind. He wears a self-made Inca quipu, each knot representing certain accomplishments he made in space exploration throughout his life. He wants to live without obsessions such as white foods, focus more on life than the stars, and temporarily live in an Altadena, California monastery to make "a transition into reentry." As seen in "Trust Metric", Larry enjoys his time of contemplation and has let his facial hair go, but still has time to dispense advice to Charlie, whether it be mathematical or about life, and even participate in a CalSci student tradition.
The only one with visitors at the monastery, Larry has been rejected by the monks and believes it is time to return from his inner reflections. He misses Megan. When he returns to his office he is ashamed and disgusted by the mess, and, hence, is getting rid of each item, albeit single-handedly for sentimental reasons. Dr. Fleinhardt asserts that he is only going to teach one seminar the whole academic term and is going to continue the search for the Higgs boson, the 'God Particle', with the DØ experiment team, as he received a "tantalizing offer" from them. Amita further points out that this is in line with his spiritual endeavor, after she says that he wants more from life than his recent habit of just walking in gardens, and he shares the same view. Larry reveals he still doesn't have a home when he suggests that Alan would be able to stay with him if he had a place.
In "Tabu", Larry and Megan have become closer again, as she has even asked him to come on the trip to New York to be with her father. He notes his wanderlust has stoked in him the desire to visit New York anyway. As custodian to Brother Theo's rabbit, however, he must speak with him first.
He and Amita spend at least twenty hours a week doing DØ research, though Larry has a crisis of conscience regarding his Higgs boson work in "End Game". In "When Worlds Collide", it is revealed that Megan is leaving the FBI to go back east, to which Larry says that their relationship has never depended on geographic proximity.
In episode 4x12, "Power" (air date 1-18-2008), Fleinhardt accepts an invitation to join Fermilab's Dzero collaboration, working to solve the mysteries of the universe and find the Theory of Everything. Co-writer Nick Falacci offered the following explanation for this plot development: "Like real-life physicists, Fleinhardt hit a roadblock trying to create an 11-dimensional supergravity theory. The search for an answer takes Fleinhardt to his particle physics roots and a cutting-edge study of extra-dimensional gravitons and the Higgs boson -- DZero and its sister detector collaboration, CDF, are leaders of that search at the energy frontier." Interestingly, DZero members have taken a fondness to the show's reference to their research and have created an office for the fictional particle physicist in the assembly building.