(written from a Production point of view)
The Big Bang Theory (2007-2019) was a long-running CBS sitcom about four nerdy CalTech scientists (the insecure Leonard Hofstadter, the severely empathetically challenged Sheldon Cooper – who fancies himself a kindred spirit to Spock and Data – , mama's boy Howard Wolowitz and lovelorn Raj Koothrappali) and the hot girl Penny who lives across the hallway and whom Leonard carries a torch for.
Being passionate comic book collectors, the four scientists are also rabid science fiction fans and collectors of memorabilia thereof, Star Trek and Star Wars in particular, resulting in the show featuring a constant flow of Star Trek references in the vast majority of the show's episodes. Other franchises the four are fan of include among others Stan Lee's Marvel Comics universe, Ronald D. Moore's Battlestar Galactica, and the British Doctor Who and Red Dwarf franchises, also referenced to on the show, albeit far less frequent than Star Wars and Star Trek. Of all the Star Trek productions, I AM ERROR, I AM ERROR, and their respective Star Trek films are the most frequently referenced to, with the others barely touched upon, if at all – specifically I AM ERROR in the latter case. This in itself is reflective of the status these two productions hold in the awareness of the general (non-fan) populace. Similarly, Star Trek II: The Wrath of Khan is the most referenced to film, likewise reflecting its status.
A major recurrent secondary character on the show is the socially awkward and consistently strapped-for-cash Stuart Bloom, owner of the comic book store the four protagonists frequent, and who, in an instance of cross-fertilization, has the in-universe animal Stuart named after him. (After Trek: "4")
Recurrent guest stars on the show include Brian George and Keith Carradine as Raj's and Penny's fathers, Pasha Lychnikoff as a cosmonaut on the International Space Station, Mark Harelik as the CalTech physics department chairman Gablehauser, with Stephen Hawking as himself. Star Trek actors Wil Wheaton, Leonard Nimoy, George Takei, LeVar Burton, Brent Spiner, and ultimately William Shatner have all made appearances on the show, as fictionalized versions of themselves, in Wheaton's and Burton's cases recurrent ones. Cast member Kaley Cuoco ("Penny") also played Shatner's daughter in Priceline.com commercials, starting in 2013 while The Bang Theory was in its sixth season , and Iris Bahr had appeared in the original unaired pilot for the show. Non-performing Star Trek alumni who had made (cameo) appearances as fictionalized versions of themselves included D.C. Fontana, David Gerrold, Adam Nimoy, Neil deGrasse Tyson and Stan Lee, the latter three in speaking parts.
Generic Star Trek references
Miscellaneous Star Trek merchandise
Even when Star Trek is not directly referenced to in the individual episodes, a multitude of its merchandise from various manufacturers is featured throughout the entire series as either props (most notably uniforms and handheld props, thereby constituting something akin to product placement), background set dressings in the homes of the four scientists or as merchandise in the comic book store they frequent. This merchandise originated from the archives of CBS Consumer Products, where it is habitually kept. Merchandise that warrants special attention, is addressed in their respective individual episode entries, listed below.
"Wild Stacks" video slot machine
Leonard Nimoy homage
Upon the the passing of Leonard Nimoy in February 2015, The Big Bang Theory paid tribute to the Spock performer in the season 8 episode "The Colonization Application" (Ep. 17, aired on 11 April 2015) by closing out with a final end title card that read "The impact you had on our show and on our lives is everlasting."
Aside from being referenced to on numerous occasions in prior (and later) episodes of the show, both as performer as well as his Spock alter ego, Nimoy had already made his voice-over appearance on the show in the season 5 episode "The Transporter Malfunction" (Ep. 20, see below) which had aired on 29 March 2012.
Original unaired pilot
Season 1 (2007-2008)
"The Pancake Batter Anomaly" (Ep. 11)
Sheldon and Leonard play three-dimensional chess.
"The Bat Jar Conjecture" (Ep. 13)
The episode begins with Howard announcing new info on the then-upcoming Star Trek film, which leads into a discussion about alien private parts and Spock's conception. Later Sheldon is persuaded to join in the Physics Bowl by quoting Spock's dying words. Sheldon "designs" shirts for his own Physics Bowl team, which bear an "uncanny" resemblance to TOS-style uniforms, with his teammates clad in red shirts and being otherwise prohibited to speak up during the contest, whereas Sheldon wears a command-gold shirt and is the only one allowed to answer questions – which had been the reason why he was ousted from his friend's team to begin with. Ultimately in the final scene, to satisfy who is smarter between Leonard and Sheldon, Penny asks multiple real-world questions for which they are only able to give Star Trek-like answers, including Patrick Stewart or William Shatner being the Sexiest Man Alive and Tweety Bird thinking he saw a Romulan.
"The Nerdvana Annihilation" (Ep. 14)
The guys purchase a time machine prop from the movie The Time Machine and they decide to play with it. They wonder what time date to travel to and Sheldon suggests to Leonard that he should travel to the future to obtain a cloaking device and references "The Enterprise Incident". Sheldon gives the stardate of this episode as 5027.3, which supposedly converts to January 10th, 2328.
Later, Leonard threatens to open up a Geordi La Forge action figure that's still in its original packaging.
Season 2 (2008-2009)
"The Bad Fish Paradigm" (Ep. 01)
"The Codpiece Topology" (Ep. 02)
Sheldon Cooper goes to a Renaissance fair dressed up like Spock pretending he's on a planet with a Renaissance theme due to the fair's complete disregard for historical accuracy.
"The Panty Pinata Polarization" (Ep. 07)
"The Lizard-Spock Expansion" (Ep. 08)
Sheldon expands the game of Rock-Paper-Scissors with additional options of "Lizard" and "Spock," the latter symbolized by the Vulcan live-long-and-prosper hand gesture. It was used initially to determine whether or not to watch I AM ERROR. Later, Sheldon and Raj argue whether Star Trek: The Motion Picture or Star Trek V: The Final Frontier is the worst Trek movie, and whether Star Trek II: The Wrath of Khan or Star Trek IV: The Voyage Home is the best.
"The White Asparagus Triangulation" (Ep. 09)
Sheldon compares Dr. Stephanie Barnett as the Leonard McCoy to their social group's "landing party" and gives a somewhat off version of the Vulcan salute when he notices her observing the conversation.
"The Bath Item Gift Hypothesis" (Ep. 11)
Penny gives Sheldon a used napkin autographed by Leonard Nimoy as a Christmas present. She apologizes because Nimoy wiped his mouth with it, but a more than overjoyed Sheldon is even more grateful, as now he has Nimoy's DNA, claiming he now will soon be able to "grow" a Leonard Nimoy for himself.
"The Dead Hooker Juxtaposition" (Ep. 19)
Penny compares the main characters' social naivete to not knowing how to put up their shields like on Star Trek.
"The Hofstadter Isotope" (Ep. 20)
"The Vegas Renormalization" (Ep. 21)
Sheldon's frequent answer of Spock during Twenty Questions.
"The Classified Materials Turbulence" (Ep. 22)
Leonard says that Howard's zero-gravity toilet for the International Space Station will allow its crew "to boldly go where no man has gone before."
Season 3 (2009-2010)
"The Electric Can Opener Fluctuation" (Ep. 01)
Penny references Star Trek as part of her comforting of Sheldon after he learns Leonard, Howard, and Raj had faked his discovery of magnetic monopoles in order to keep him happy. Sheldon wears a goatee resembling the one Spock wears in TOS: "Mirror, Mirror". A recurring joke is Sheldon's "Vulcan hearing."
"The Creepy Candy Coating Correlation" (Ep. 05)
Sheldon states he used to be a Wil Wheaton fan until Wil abruptly pulled out of a convention Sheldon had traveled ten hours by bus to attend and get his autograph. During a customizable card game tournament Wil is participating in, Sheldon constantly quotes Khan Noonien Singh from Star Trek II: The Wrath of Khan, uttering the proverb "Revenge is a dish that is best served cold" in original Klingon. When Wheaton tricks Sheldon out of a sure victory, Sheldons cries out "Wheaton" to the heavens, in imitation of Kirk's "Khan" cries in The Wrath of Khan.
"The Adhesive Duck Deficiency" (Ep. 08)
Trying to get Sheldon to drive faster, Penny says, "Warp speed ahead, Mr. Spock", to which Sheldon replies that that order would never be given to the science officer, but to the navigator/helmsman instead.
"The Maternal Congruence (Ep. 11)
When Leonard asks what he truly wants, Sheldon answers, "What I want is to be departing on the starship Enterprise in a one-man shuttlecraft headed for the planetoid I rule, known as Sheldon Alpha Five."
"The Bozeman Reaction" (Ep. 13)
"The Large Hadron Collision" (Ep. 15)
In order to persuade Leonard, who is planning to take Penny along as a Valentine gift, to take him instead to the CERN Large Hadron Collider in Switserland, Sheldon goes even as far as allowing Leonard to watch Babylon 5. Prohibited to be seen by Sheldon, Leonard loves the series but had until then lost each and every argument they had over it. However, Sheldon is so desperate to go to CERN that he purports to set aside his disdain for the series, even though it, according to him, "(...)failed as drama, science fiction and is hopelessly derivative".
"The Excelsior Acquisition" (Ep. 16)
Sheldon reveals that Leonard Nimoy took a restraining order out against him after receiving one from Stan Lee. Additionally, when Leonard is asking Penny to guess who Stan is, she incorrectly assume he was on Star Trek.
"The Precious Fragmentation" (Ep. 17)
"The Pants Alternative" (Ep. 18)
"The Wheaton Recurrence" (Ep. 19)
"The Staircase Implementation" (Ep. 22)
"The Lunar Excitation" (Ep. 23)
As Howard and Raj, having secretly signed Sheldon up with an online dating service, try to convince him to at least meet the woman he has been matched with, Raj reminds him that even Spock dated once every seven years, so Sheldon quickly shoots back that pon farr had nothing to do with dating: "His blood boiled with mating lust".
Season 4 (2010-2011)
Season 4 promotional ads
In one, Sheldon builds an Original Series transporter to beam them (with Next Generation-style visual effects) from their old Monday night timeslot to Thursday. In another he and Leonard again play three-dimensional chess while discussing the move.
"The Hot Troll Deviation" (Ep. 04)
Howard has a USS Enterprise-D model in his bedroom. An imaginary George Takei (wearing his Hikaru Sulu costume from Star Trek IV: The Voyage Home) appears to give Howard romantic advise. Likewise, actress Katee Sackhoff appears as her Battlestar Galactica counterpart, for whom Howard has the hots, and starts bickering with Takei, questioning his credentials to give Howard romantic advise, while poking fun at Takei's homosexuality. Both however, are also lamenting and exchanging notes on being typecast as Sulu and Starbuck respectively.
"The Apology Insufficiency" (Ep. 07)
Taken as proof that he has wronged Howard, Sheldon is dreaming of a Gorn sitting on the couch reading a magazine. He later compares his problem of Howard refusing to accept his apology with the no-win Kobayashi Maru scenario, and is impressed by Penny's knowledge that Kirk cheated on the test, enticing him to try something similar on Howard. Later he is introduced by Raj to the visiting Neil deGrasse Tyson at CalTech, but Sheldon scolds him for his part in the declassification of Pluto from a planet to dwarf planet, and refuses to accept his apologies for it later on, stating that Tyson needs "to get over himself".
"The 21-Second Excitation" (Ep. 08)
Leonard mentions how they all waited fourteen hours to see Star Trek Nemesis. Later, when Wil Wheaton – deemed the Jar Jar Binks of the Star Trek universe by Sheldon – jumps the line to see Raiders of the Lost Ark, Sheldon quotes Picard's "The line must be drawn HERE!" line from Star Trek: First Contact.
"The Boyfriend Complexity" (Ep. 09)
Howard and Raj play a game of Star Trek-themed battleships. When Howard notices that two squares are a hit but the one in the middle is a miss, Raj comments that his starship has a hole in the middle. When asked what starship has a hole in the middle, Raj says "a Romulan battle bagel."
"The Alien Parasite Hypothesis" (Ep. 10)
"The Bus Pants Utilization" (Ep. 12)
Sheldon's passive-aggressive stance against the guys for kicking him out of their app design team includes playing the Original Series theme on a theremin. Before he was kicked out Sheldon listed himself as the "Star Trek Science Officer" of the design team.
"The Love Car Displacement" (Ep. 13)
Leonard uses the Romulan Neutral Zone as a metaphor for how he and Penny will share a bed without becoming intimate. When he suggests they do get intimate in the context of how often the Neutral Zone was entered by both the Federation and Romulan Star Empire, Penny says she's raised shields over the lower half of her body.
"The Thespian Catalyst" (Ep. 14)
"The Toast Derivation" (Ep. 17)
Sheldon invited LeVar Burton over to the apartment via Twitter. At the end of the episode, he sticks his head in and gets too weirded out by the sight of three other guys singing karaoke. He then leaves and says he's so done with Twitter.
"The Prestidigitation Approximation" (Ep. 18)
Leonard says to Priya that the only Star Trek uniforms he has are the everyday and dress ones from the Original Series, and then she reveals that Raj has an Uhura dress when Leonard suggests she wear one.
"The Zarnecki Incursion" (Ep. 19)
Sheldon carries a bat'leth with him to the house of the guy who hacked his World of Warcraft account.
"The Agreement Dissection" (Ep. 21)
Sheldon cites "Let That Be Your Last Battlefield" as his inspiration for blackmailing Leonard into signing a new roommate agreement that favors him. He then shows an okudagram-styled auto-destruct-esque countdown timer on his laptop showing how much time Leonard has before Priya's parents are emailed about her dating Leonard. Sheldon then tells her that while she may have gone to the Faculty of Law at Cambridge University, he's an honorary graduate of Starfleet Academy.
"The Wildebeest Implementation" (Ep. 22)
Sheldon's three-player variation of chess includes a space designated as a transporter pad.
"The Roommate Transmogrification" (Ep. 24)
Raj overhears Leonard and his sister Priya having an Original Series-themed sex fantasy.
Season 5 (2011-2012)
"The Russian Rocket Reaction" (Ep. 05)
Wil Wheaton throws a party at his house, which has a painting of him as Wesley Crusher in uniform and an Enterprise-D model. Raj says he talked with Alice Krige's gynecologist, referring to Alice as "The Borg Queen From First Contact." Wil gives Sheldon an autographed still-in-package Playmates Toys Wesley action figure, but Brent Spiner promptly opens it upon seeing it. Brent then offered Sheldon a autographed still-in-package Data action figure to make up for it, but Sheldon declines and declares Brent his new mortal enemy.
"The Rhinitis Revelation" (Ep. 06)
There's a Next Generation tricorder displayed on the bookcase behind the couch.
"The Good Guy Fluctuation" (Ep. 07)
Dispelling his claim that he is too intelligent to be surpised by Halloween pranks, Sheldon is literally scared senseless when Leonard does surprise him wearing a Balok mask.
"The Ornithophobia Diffusion" (Ep. 09)
While the two are on a date in a bar, they start bickering and Penny tells a girl that Leonard owns two Star Trek uniforms and that he wears them outside the Halloween holidays as well.
"The Recombination Hypothesis" (Ep. 13)
"The Vacation Solution" (Ep. 16)
Bernadette had rejected Howard's suggestion to have wedding invitations in Klingonese.
"The Rothman Disintegration" (Ep. 17)
Kripke has Sheldon explain Rock-Paper-Scissors-Lizard-Spock to him at least three times to mess with him. Sheldon later proposes a trivia contest with The Original Series, The Next Generation, Deep Space Nine, and Voyager being four of the five categories.
"The Weekend Vortex" (Ep. 19)
Amy mistakenly refers to the Star Wars video game the guys are playing as a Star Trek video game. Penny corrects her, saying the guys don't like when the two franchises are mistaken for one another, even though Penny, as far as she herself is concerned, does not perceive any difference between the two either.
"The Transporter Malfunction" (Ep. 20)
Penny bought Sheldon and Leonard a mint-in-box 1975 Star Trek transporter toy each. However, they refused to play with them as the toys would lose some of their perceived value within toy collector circles. That night, Sheldon dreamed that his Mr. Spock action figure told him that it was illogical to own a toy that he wouldn't play with. Shortly afterwards, Sheldon accidentally broke his transporter while playing with it and then replaced it with Leonard's. Later, he had a nightmare about being chastised by Mr. Spock about his actions and was subsequently attacked by a Gorn. Appropriately chastened, Sheldon confessed his guilt to his roommate.
"The Hawking Excitation" (Ep. 21)
Howard says "no" in Klingonese when telling Sheldon that he wouldn't introduce him to Stephen Hawking.
"The Stag Convergence" (Ep. 22)
Sheldon tells Wil Wheaton (who said he was attending Howard's bachelor party because it was a welcome alternative to George Takei's hot tub parties) to "talk to the hand" and gives him the Vulcan salute.
"The Launch Acceleration" (Ep. 23)
Howard tells Raj "You watch Star Trek, I live it" when discussing Howard's aborted mission to the International Space Station. Leonard and Sheldon again play three-dimensional chess. Later, Leonard comes home to find Sheldon and Amy playing "Star Trek doctor" with Sheldon uncomfortably lying on the couch while Amy, dressed in a sciences division blue Original Series women's uniform, pretend-scans him with a toy medical tricorder.
"The Countdown Reflection" (Ep. 24)
Despite his initial offer to do so being soundly rejected, Sheldon performs part of Howard and Bernadette's wedding in Klingonese and says "and the Klingon High Council" when pronouncing them man and wife.
When the rocket is launched, Sheldon quotes the title sequence from The Original Series saying "Boldly go, Howard Wolowitz".
Season 6 (2012-2013)
"The Habitation Configuration" (Ep. 07)
Sheldon tries to do a segment on Trek flags on his "Fun With Flags" web show, first with Wil Wheaton (who keeps trying to do a bit on the Federation flag much to Amy's dislike) and later with LeVar Burton, telling his viewers to "set phasers to fun." To get Amy to see things his way in the matter, Sheldon gives her the TNG Complete Series DVD Boxset and "briefly" describes "Encounter at Farpoint" to her through her closed apartment door. Wil's house number is 1701, the Enterprise's hull number.
"The Fish Guts Displacement" (Ep. 10)
Amy suggests that Sheldon punish her by not letting her see the new Star trek movie, which Sheldon however finds a too harsh punishment not befitting the "crime" – to the dismay of Amy.
"The Egg Salad Equivalency" (Ep. 12)
When the two are discussing their day over dinner, Leonard mentions to Penny that he found an online quiz called "Which Star Trek character are you?", proudly stating that it only took him four tries to get Captain Kirk. When he starts to use Kirk's intonation, Penny cuts him short.
"The Bakersfield Expedition" (Ep. 13)
While driving to the Bakersfield, California Comic-Con, the guys stop at Vasquez Rocks to pose for photos in their The Next Generation costumes: Leonard as Picard, Sheldon as Data, Raj as Worf, and Howard as a Borg. After their car gets stolen, Sheldon states that they're all a landing party, obligated as such to overcome hardships. Failing to get a lift and being thrown refuge at by a passing car, its driver shouting "nerds" at them, the boys eventually stumble into a roadside restaurant in their disheveled Star Trek outfits, being met with wary bemusement by the other patrons, chuckling at the "trekkies" – particularly after the "Borg" Howard asks if his mother should pick them up. The ordeal causes the despondent boys to question their love for Star Trek. After it is decided to rent a car instead to return home, Raj, more steadfastly holding on to his love, asks if the car can be from the rental agency Enterprise.
At the same time the boys have their ordeal, Chris Hemsworth's Marvel Comics character Thor becomes a point of argument for Penny, Amy, and Bernadette, when they made an effort to understand their boyfriends' nerdiness. When the boys return home, weary of being trekkies because of their ordeal, they incredulously overhear their girlfriends' heated nerd discussion, causing their own inner nerds to be revitalized. On the assumption they have stumbled into an alternate reality and with their disheveled costumes put in order, the revived landing party prepares to break into the room to investigate with "phasers on stun", since Leonard in particular does not want to "vaporize" Penny, as he will never be able again to get another girlfriend that gorgeous.
"The Contractual Obligation Implementation" (Ep. 18)
While discussing the advancement of women in science, Sheldon names Star Trek writer D.C. Fontana as a woman who had to use her initials to hide her gender in her field of work. He also states he is preferential to a gender-blind society like in Star Trek, which is put in perspective by Leonard who observes that while warp drive was invented in that society, a black woman still had to answer the phone. Leonard's observation entices Howard to chime in with him reminiscing about how "many times he spent alone with Lt. Uhura in the shower."
"The Love Spell Potential" (Ep. 23)
Sheldon says he's tired of Leonard always invoking Zachary Quinto whenever Sheldon doesn't like an impending change.
"The Bon Voyage Reaction" (ep. 24)
Sheldon explains his personal trick to overcoming his social anxiety was to picture everyone as a Star Trek character. Apparently Raj is "Uhura" while Leonard is "Unnamed Crew Member In A Red Shirt".
Season 7 (2013-2014)
"The Hofstadter Insufficiency" (Ep. 01)
During Leonard's absence, Penny and Sheldon play a game of 3D chess. Sheldon also starts to ask Penny about Starfleet captains, before being cut off by her.
"The Discovery Dissipation" (Ep. 10)
To help Sheldon feel better about Leonard disproving his discovery of a new element, Wil Wheaton comes by and tells Sheldon that for a while he regretted being Wesley Crusher.
"The Cooper Extraction" (Ep. 11)
Sheldon is absent during the Christmas season, and while the gang is decorating the Christmas tree, Raj asks if the tree can now sport both Star Wars and Star Trek ornaments on the same branch, to which Leonard answers, "I know, it’s crazy. Welcome to the Thunderdome, people."
Season 8 (2014-2015)
"The Expedition Approximation" (Ep. 06)
During a deep cave simulation in an abandoned mine, Raj makes a remark about Voyager, Sheldon inquires which Voyager Raj means, the actual deep space probe or I AM ERROR, the television show. After Raj confirms he is talking about the actual space probe, Sheldon retorts, "Good. Because I am too hot and tired to go on about how much I hate Voyager the TV show." In the meantime Howard and Bernadette have a heated argument on what each spouse brings into the marriage, with the high-earning Bernadette scoffingly accusing Howard to have only brought in his Star Trek collectable plate collection, and an incomplete one at that. Howard indignantly retorts he just completed the collection with the purchase of the last missing one on eBay, but tries to dodge Bernadette's inquiry for how much, after which the argument flares up again in full force.
"The Misinterpretation Agitation" (Ep. 07)
Sheldon offers a beverage to a Dr. Oliver Lorvis after he admits his intention to give some flowers to Penny. Later when receiving his drink, Lorvis, turning out to be a rabid science fiction memorabilia collector himself, compliments Sheldon's Star Trek mug and mentions that he got an original phaser, after having given Gene Roddenberry a vasectomy. Lorvis also divulges that he had helped William Shatner with kidney problems, having received from him an original tribble for his troubles, though he was not sure if it in effect had not been Shatner's toupee all along.
"The Champagne Reflection" (Ep. 10)
Sheldon introduces LeVar Burton for the final "Fun With Flags" webisode by saying he "puts the Geordi in your La Forge." Later LeVar says he should've taken Wil Wheaton's advice about getting a gate for his house when Sheldon tells him the web show's been resurrected.
"The Clean Room Infiltration" (Ep. 11)
At Amy's Christmas party, Dr. Koothrappali (Raj's father who has recently divorced and is visiting from India) states that it is too soon to be dating again. Penny says she would if she was free, but pauses to inquire if he is not also talking about Star Trek all the time.
"The Colonization Application" (Ep. 17)
After he has wronged Amy, Sheldon tries to make amends by suggesting to play The Original Series theme through his nose. When he starts to do so, a still irked Amy cuts him short.
Season 9 (2015-2016)
"The Spock Resonance" (Ep. 07)
Wil Wheaton and Adam Nimoy come over to interview Sheldon for Adam's documentary about Leonard Nimoy, or as Sheldon put it, a "Spockumentary", quickly attributing the too obvious witticism to his roommate Leonard when it does not solicit any laughs. Sheldon tells the pair that the episode that really had meaning in his life was "The Galileo Seven". He also mentions that as a child he tried to perform a Vulcan neck pinch on a bullying schoolmate, which however only netted him a broken collarbone. He also divulges that he has left Wheaton in his will the Wesley Crusher action figure, he was gifted earlier by him in the episode "The Russian Rocket Reaction". During their visit, Sheldon presents the napkin complete with Nimoy's DNA that he received from Penny as gift in the second season "The Bath Item Gift Hypothesis". While interviewed, Sheldon's recent breakup with Amy becomes topic of the conversation, which he at first claims does not emotionally affect him, as he, like Spock, is above human emotions. When Penny – of all people – however points out to Sheldon that Spock was half-human, and thus in part an emotional creature, Sheldon, clearly struggling with his feelings for Amy, breaks down and storms out of the room.
Later that evening, Sheldon reemerges from his room and informs Leonard and Penny that he is going to propose to Amy (which he until then unbeknownst to the others had already intended before the breakup) and get it over with either way, citing the Vulcan proverb "Kup-fun-tor ha'kiv na'ish du stau?" ("Can you return life to what you kill?"). Penny asks Leonard, if he understands what Sheldon is saying which he firmly denies, though timidly restating "no" in Vulcan ("nirsh") when she gives him the stink-eye. Before leaving, Sheldon exclaims that Amy can just "ponfo mirann" ("go to hell") if she should refuse him. "He doesn't mean that," Leonard quickly says to Penny when she again looks at him quizzingly, completely destroying his credibility. Sheldon leaves for Amy's apartment, but finds her kissing another man in font of her building. After returning, a despondent Sheldon re-watches "Where No Man Has Gone Before", scoffing at Spock for his claims of being unemotional at the beginning of the episode.
"The Mystery Date Observation" (Ep. 08)
In an effort to get over Amy, Sheldon solicits the help of Howard and Raj to help him find a new mate, as they had managed to do so with Amy through a dating site. They decide on a slightly different approach this time in singling out women, who meet all of Sheldon's many, many specifications by devising an online contest in which women can win the opportunity to meet Sheldon in person after having solved a series of puzzles, devised by Sheldon. One of the puzzles is to translate a Klingon text in ancient Sanskrit. As they had already been earlier with Amy, Howard and Raj are flabbergasted when a handsome female scientist actually shows up at Sheldon's door quoting the text in impeccable Klingon and in its Sanskrit translation. Furthermore, she seems to tick of all of Sheldon's boxes, while chatting with him. However, much to the consternation of his friends, Sheldon turns her away as she showed up one minute after the set deadline of the test had expired, as well as having solved the test while being bored by a symposium on atomic spectroscopy, the latter being a deal breaker for Sheldon.
"The Opening Night Excitation" (Ep. 11)
"The Meemaw Materialization" (Ep. 14)
While discussing his recent reconciliation with Amy, Leonard "points" out to Sheldon that he owns two pairs of Spock ears; one for ComicCon and one for around the house.
"The Celebration Experimentation" (Ep.17)
Wil Wheaton gives a speech during Sheldon's birthday party, stating that while Sheldon may be a Star Trek fan, he has become a Sheldon fan and concludes with the traditional Vulcan "Live long and prosper" valediction. Sheldon turns to Howard, who had just given a more traditional birthday speech, saying, "That's how you do it, Wolowitz. Now you see why he's famous and you're not". A short time later Stephen Hawking also chimes in via Skype, singing Happy Birthday.
Season 10 (2016-2017)
"The Military Miniaturization" (Ep. 02)
During an attempt to sell a by them invented guidance system to the military, under the proviso not to use it for lethal purposes, Colonel Williams states, "Look guys, its just a guidance system. It's not like you're handing me the Death Star from Star Trek." Forced by his his friends to remain silent as not to endanger their pitch, Sheldon nearly suffers from a stroke, because of the inaccuracy. When Williams subsequently assumes Howard to be the brains behind the invention, praising his engineering skills and his education at MIT, Sheldon can no longer contain himself and blurts out, "I'm Dr. Sheldon Cooper. I'm the actual brains behind this project. Also, engineers aren't real scientists, MIT is a trade school, and the Death Star is from Star Wars not Star Trek. Otherwise, thank you for your service."
"The Cohabitation Experimentation" (Ep. 04)
When Sheldon exhibits trepidation to switch apartments in order for both boys being able to live together with their respective paramours, Leonard entices Sheldon to do so, by comparing the five week experiment to The Original Series, stating,"The Enterprise was on a five-year mission to explore new worlds. Think of this as your own personal five-week mission to do the same," to which Shelon replies, "If you want to lure me in with sexy talk, that’s how you do it." Very pleased with his own Star Trek wit, a smug Leonard is quickly put back in his place when Penny says that it is nothing to be proud of.
Season 11 (2017-2018)
"The Retraction Reaction" (Ep. 02)
"The Relaxation Integration" (Ep. 03)
Sheldon tells Amy that he will appear at their wedding with a tuxedo over a Star Trek uniform.
"The Explosion Implosion" (Ep. 04)
Leonard owns a Captain Kirk shirt, which needs to be dry cleaned.
"The Proton Regeneration" (Ep. 06)
Sheldon competes with Wil Wheaton for a role in a remake of "Professor Proton". Wheaton gets the part, and is put back on Sheldon's list of enemies.
"The Bow Tie Asymmetry" (Ep. 24)
Wil Wheaton is slated to officiate the wedding of Sheldon and Amy, but his place is unceremoniously usurped by the by Howard arranged surprise guest Mark Hamil, the Luke Skywalker actor from Star Wars. Miffed, Wheaton acidly states, "So we finally meet", and when Hamil does not recognize Wheaton, the latter starts bickering with Hamil throughout the entire ceremony.
Season 12 (2018-2019)
"The D & D Vortex" (Ep. 16)
Will Wheaton brings William Shatner on his Professor Proton show to meet Sheldon, who unfortunately gets so excited to meet "Captain Kirk" as "Science Officer Cooper" that he vomits all over him. Later, the boys find out that Wheaton has Stuart, alongside Shatner and other celebrities, included as part of a Dungeons & Dragons role playing game group. Leonard but not the other guys, and certainly not Sheldon, gets invited after Stuart drops out, but sworn to secrecy, cannot refrain himself from telling Penny, and thus the other two girls, who then accost Wheaton as one of the other celebrities is an actor the girls have the hots for. Leonard is subsequently thrown out by a miffed Wheaton, though he surreptitiously allows the girls to participate, as a form of punishment. During the game Shatner annoys his fellow gamers by making a constant flow of Star Trek references such as "I was about to go all Wrath of Khan on the ogres", and every time he does so, he has to put money in a Star Trek "swear jar", which he finds totally "worth it".
"The Decision Reverberation" (Ep. 20)
Spurred on by Penny to exert some much needed assertiveness, Leonard "confidently" tells Penny they are going to watch I AM ERROR after they have had sex. Penny concedes but notifies Leonard she will be mostly watching her smartphone after sex.
The Big Bang Theory universe was expanded significantly when in 2017, the prequel spinoff "Young Sheldon" was launched, focusing on the childhood of Sheldon Cooper in his home state of Texas, elaborating on the many childhood events Sheldon has mentioned over the course of the main series. The cast includes Wallace Shawn as Dr. John Sturgis, the boyfriend of Cooper's maternal grandmother; Jason Alexander recurs as Gene Lundy, the high school drama teacher; while Harry Groener guest-starred in the first season episode "An Eagle Feather, A String Bean & An Eskimo" in 2018.
One of young Sheldon's favorite television shows he regularly watches in the series is Carl Sagan's acclaimed 1980 popular science series Cosmos: A Personal Voyage. That series was served by visual effects company Magicam, Inc., the company that had previously provided the studio models for Star Trek: The Motion Picture prior to the Cosmos assignment. Their work on Sagan's show had earned the company three Emmy Awards. An updated and modernized remake – or sequel – , Cosmos: A Spacetime Odyssey, was aired in 2014. Produced by former Star Trek showrunner Brannon Braga, it was hosted by Neil deGrasse Tyson who was inspired to embark on his scientific career because of Sagan and his show.