Leslie Winkle

Leslie Winkle, Ph.D., is an experimental physicist at the California Institute of Technology who works in the same lab as Leonard. She is essentially his female counterpart, equipped with the same black framed glasses and zippered hoodies. Whenever depicted in the lab, she is always using the equipment inappropriately to prepare food, such as flash-freezing a banana with liquid nitrogen and then shattering it with a hammer to put in her cereal, or using a helium-neon laser to heat a cup of instant soup. She dates Leonard on-and-off, and later Howard. Because of her shallow and manipulative nature, she is arguably the central antagonist of the second series. Leslie made her final appearance in "The Lunar Excitation" and left the series after that.

Career
Leslie specializes in high energy physics, particularly searching for supersymmetry with like-sign dileptons. Leslie believes loop quantum gravity is the future of physics and better unites quantum mechanics with general relativity than string theory does. She posits that only loop quantum gravity calculates the entropy of black holes and expects quantized spacetime to manifest itself as minute differences in the speed of light for different colors.



Relationships
Leonard tries to ask her out because he considers her to be in his league and they decide to kiss to see if they have chemistry. Though Leslie compliments Leonard on his kissing technique, Leslie feels no arousal, and thus, no date occurs. She eventually puts forth an offer of sexual availability towards Leonard one evening after a string quartet practice in which she plays the violin, and the two engage in sexual intercourse, but she reveals that she only desires sex infrequently while distracted by a difficult project and subsequently dumps him, claiming she'll be satisfied until at least New Year's Eve.

Initially uncomfortable with commitment, she later comes to the realization that "there’s just a time in every woman’s life when she gets tired of waking up on a strange futon with a bunch of people she doesn’t know." Leslie briefly tries to rekindle her relationship with Leonard after his failed attempt at dating Penny, stating that she is "fully committed to the traditional relationship paradigm" and "who better to slow things down with than you?" She even considers Leonard as a potential mate, going so far as asking Leonard how many children they should have. However, it does not work out because of Leslie's belief in loop quantum gravity and Leonard's belief in string theory, which is, as she put it, a "deal-breaker."

In "The Cushion Saturation", during a Caltech paintball game, she begins an affair with Howard Wolowitz, making her the fifth woman to sleep with Howard without being paid. She allows him access to experimental equipment (like a rapid prototyper) in spite of budget cuts and a research trip to Geneva to check out CERN's supercollider, using some unrestricted grant money Caltech gave her. She essentially controls Howard with new equipment and research trips, so as to avoid a real relationship with feelings, and institutes a "friends with benefits" arrangement instead, which she is more used to. However, in "The Vegas Renormalization", she dumps him over the phone, simply saying "Howard, momma’s a rolling stone."

In "The Lunar Excitation", when Leonard appears at her door, Leslie reveals it has been eighteen months since they have seen each other. He asks if she wants to have sex with him just for fun like they used to. She quickly deduces that Penny dumped him and says she would like to think about it, before she slams the door. Leonard realizes she is not going to come back.

Sheldon's Archenemy
Sheldon regards her as his archenemy, playing the role of a Dr. Doom to his Mr. Fantastic. She, at some point in the past, made Sheldon cry. It is also shown Sheldon didn't use to have a problem with Leslie however after her first dalliance with Leonard, she was able to fix a problem Sheldon was having in showing that quarks are asymptotically free at high energies by changing the sign of the beta function β(g) of quantum chromodynamics (QCD) on his whiteboard in "The Hamburger Postulate"; this act greatly irritated him. Since then, whenever she sees Sheldon, she tries to insult him. Sheldon thinks her research methodology is sloppy, asserts that she’s unjustifiably arrogant about loop quantum gravity and that the only way she could make a contribution to science would be if they resume sending chimps into space. To make matters worse, according to Sheldon, she's often mean to him. Meanwhile, Leslie Winkle considers Sheldon an "arrogant, misogynistic East-Texas doorknob" who one time told her she should abandon her work with high energy particles for laundry and child bearing.

A frequently used insult (or a slight variation) by Leslie is "Hello, fellow scientists. Hello, Sheldon." Her favorite quip to him is "Hello, dumbass." When Sheldon received a phone call during a meeting with Dr. Eric Gablehauser, she hoped he wouldn't miss a call from the Nobel committee informing he had been nominated as dumbass laureate of the year. Similarly, when Sheldon was working toward a breakthrough with his theory of string-network condensates at lunch in the Caltech cafeteria,  she remarked that he was organizing his papers for the Smithsonian Museum of Dumbassery. Sheldon usually stumbles to insult her, but has stated he has no respect for her as a scientist or a human being. In "The Barbarian Sublimation", Leslie postulated that Penny was escaping into the online world to compensate for her sexual frustration, only for Sheldon to concede that she had an undeniable expertise in the interrelated fields of promiscuity and general sluttiness.

When Sheldon signed up to use the mainframe in Buckman 204 at Caltech, Dr. Winkle ripped the sign-up sheet off the wall as he printed it himself and put his name down in every slot for the next six months. Sheldon maintained that he was only trying to ensure university resources are not being "squandered chasing sub-atomic wild geese." This particular dispute could only be resolved by meeting with the chair of the Physics Department, Dr. Gablehauser.

Sheldon is perturbed by Leonard's attachment to Leslie and has pondered why, of all the overrated physicists in all the labs in all the world, it had to be Leslie Winkle. Following several interruptions by Sheldon during a date she had with Leonard, she remarked that he was a "passive-aggressive East Texas blowhole". Later, in an attempt to be gracious and support his friendship with Leonard by accepting Leslie's romantic involvement with him, Sheldon claims to be willing to overlook her faults, but starts an argument that effectively nullifies her romance with Leonard by stating that she is an arrogant sub-par scientist, who prefers loop quantum gravity to string theory.

Interestingly, she serves as Sheldon's ally in a Caltech paintball match in "The Cushion Saturation" without insulting him once in that same episode, which might imply that they have settled their differences.

Trivia

 * Leslie seems to be the only person aside from Dennis Kim and Amy Farrah Fowler who has equal or greater intelligence than Sheldon.
 * When Leslie converses with Sheldon, she calls him "dumbass".

Leslie Winkle