The Big Bang Theory ( season 9 ) - wikipedia The Big Bang Theory ( season 9 ) The Big Bang Theory ( season 9 ) Ninth season DVD cover art Starring Johnny Galecki Jim Parsons Kaley Cuoco Simon Helberg Kunal Nayyar Mayim Bialik Melissa Rauch Kevin Sussman Laura Spencer Country of origin United States No. of episodes 24 Release Original network CBS Original release September 21, 2015 ( 2015 - 09 - 21 ) -- May 12, 2016 ( 2016 - 05 - 12 ) Season chronology ← Previous Season 8 Next → Season 10 List of The Big Bang Theory episodes The ninth season of the American sitcom The Big Bang Theory started airing on CBS on Monday, September 21, 2015. It returned to its regular Thursday time slot on November 5, 2015 for the season 's seventh episode. It concluded on May 12, 2016. On March 12, 2014, The Big Bang Theory was renewed for an additional three years, extending it through the 2016 -- 17 season for a total of ten seasons. Laura Spencer was upgraded to the main cast during the season as Dr. Emily Sweeney, after being a recurring cast member for two seasons. Contents 1 Production 2 Cast 2.1 Main cast 2.2 Special guest cast 2.3 Recurring cast 2.4 Guest cast 3 Episodes 4 Ratings 5 Reception 6 References 7 External links Production Like the previous season, the first six episodes of the ninth season aired on a different night due to CBS acquiring the rights to Thursday Night Football games. In May 2015, CBS announced at its annual upfront presentation, that the series would begin its ninth season on Mondays, before returning to the Thursday slot once the football games ended. Filming for the ninth season began on August 5, 2015, according to posts on Twitter by several of the cast members including Melissa Rauch and Kunal Nayyar. Laurie Metcalf reprised her role as Sheldon 's mother Mary in episodes 1 and 24, and Keith Carradine returned as Penny 's father Wyatt in episode 3. Sheldon 's maternal grandmother Constance who he calls `` Meemaw '' made her first long - awaited appearance in episode 14 and was portrayed by June Squibb and Leonard 's father Alfred also made his first long - awaited appearance in episode 24 and was played by Judd Hirsch. This was the first season to feature every main cast member of the show, including former main cast member Sara Gilbert, who made a guest appearance in the 200th episode. Cast Main article : List of The Big Bang Theory characters Main cast Johnny Galecki as Dr. Leonard Hofstadter Jim Parsons as Dr. Sheldon Cooper Kaley Cuoco as Penny Simon Helberg as Howard Wolowitz Kunal Nayyar as Dr. Rajesh `` Raj '' Koothrappali Mayim Bialik as Dr. Amy Farrah Fowler Melissa Rauch as Dr. Bernadette Rostenkowski - Wolowitz Kevin Sussman as Stuart David Bloom Laura Spencer as Dr. Emily Sweeney Special guest cast Adam Nimoy as himself Elon Musk as himself Adam West as himself Stephen Hawking as himself Recurring cast Laurie Metcalf as Mary Cooper John Ross Bowie as Barry Kripke Wil Wheaton as himself Casey Sander as Mr. Rostenkowski Alessandra Torresani as Claire Christine Baranski as Dr. Beverly Hofstadter Brian Thomas Smith as Zach Johnson Guest cast Jim Meskimen as a minister Melissa Tang as Mandy Chao Keith Carradine as Wyatt, Penny 's father Megan Heyn as Natalie Patrika Darbo as Grace Michael Rapaport as Kenny Stephen Merchant as Dave Gibbs Analeigh Tipton as Vanessa Bennett Wayne Wilderson as Travis Bob Newhart as Arthur Jeffries Jane Kaczmarek as Dr. Gallo June Squibb as Meemaw Creagen Dow as Maitre D ' Sara Gilbert as Leslie Winkle Blake Anderson as Trevor Judd Hirsch as Alfred Hofstadter Episodes See also : List of The Big Bang Theory episodes No. overall No. in season Title Directed by Written by Original air date Prod. code U.S. viewers ( millions ) 184 `` The Matrimonial Momentum '' Mark Cendrowski Story by : Chuck Lorre & Jim Reynolds & Maria Ferrari Teleplay by : Steven Molaro & Steve Holland & Eric Kaplan September 21, 2015 ( 2015 - 09 - 21 ) 4X7201 18.20 Leonard and Penny elope in Las Vegas, live streaming the ceremony for friends at home. Leonard wrote a touching cosmology - based wedding vow while Penny recites `` You 've Got a Friend in Me ''. When they kiss after he carries her over the threshold, Penny is still bothered that Leonard kissed Mandy two years ago and is outraged to hear they work together. When Leonard and Penny return home, she goes to her apartment alone. Sheldon, confused and hurt by Amy 's indecision about their relationship, insults her before all their friends watching the wedding at Howard and Bernadette 's house. Amy openly breaks with him, upon which all leave except for Howard and Stuart, who actually see the wedding to the end. Sheldon calls his mother to return his great - grandmother 's ring which he had intended for Amy, but Mary tells him to wait. Sheldon briefly considers dating Mandy to hurt Amy. He is angered that Penny knew Amy was unhappy and did not defend him. A dejected Leonard can not believe he is spending his wedding night with Sheldon, though Sheldon always expected this. Title reference : The events that are set in motion by Leonard and Penny eloping. 185 `` The Separation Oscillation '' Mark Cendrowski Story by : Steven Molaro & Steve Holland & Tara Hernandez Teleplay by : Chuck Lorre & Jim Reynolds & Maria Ferrari September 28, 2015 ( 2015 - 09 - 28 ) 4X7202 18.03 After having a nightmare of Sheldon and Penny passionately kissing, Leonard considers marriage counseling but finds it too expensive. Howard and Bernadette have long known of Leonard and Mandy 's kiss. Howard kept it from Raj, as did Bernadette from Penny. Bernadette points out to Penny that the now confident Leonard is with her because he loves her, not out of desperation. During a chat with Mandy Chao, who is not attracted to Leonard and neither remembers nor cares that she kissed him, he realizes part of himself may be trying to sabotage his marriage as he thinks he is not good enough for Penny. Penny admits fearing he will leave her for someone smarter. Both agree to abandon their fears and embrace their happiness. Sheldon surprises them with a trip to San Francisco, only to say he is going too, as he bought the tickets for himself and Amy. Sheldon returns Amy 's belongings, failing to make her jealous by `` accidentally '' putting one of Penny 's bras in the box. He records a `` Fun With Flags '' episode alone, angrily using countries that separated as metaphors for Amy dumping him. Amy, furious, demands he remove the video, for Sheldon a sign she still wants him. Title reference : Penny and Leonard get back together while Sheldon and Amy drift further apart. 186 `` The Bachelor Party Corrosion '' Mark Cendrowski Story by : Dave Goetsch & Jim Reynolds & Jeremy Howe Teleplay by : Steven Molaro & Steve Holland & Eric Kaplan October 5, 2015 ( 2015 - 10 - 05 ) 4X7203 17.40 Raj and Howard plan to kidnap Leonard for a belated bachelor party weekend and forcefully take Sheldon, who is impressed that the van they are driving once belonged to physicist Richard Feynman, and that they plan to stay at his vacation house in Mexico. When the van has a flat tire, a stuck lug nut prevents the men from fixing it. Several scientific methods all fail to remove it, but ultimately inadvertently set the van on fire. Meanwhile, the women have a small bachelorette party at Penny 's apartment. Amy reveals she has not told her family about her breakup with Sheldon, relating how her mother had her sit in a `` sin closet ''. Penny pierces Amy 's ears for her, and mentions she has not told her family she married Leonard. She reluctantly calls her father Wyatt, who is simply happy for her, though he upsets Penny on confessing he accidentally killed her pet pig a year ago. The women have Amy call her mother, but when Amy finds it difficult to tell her about the breakup, Penny tells her about Amy 's breakup, her penis cookies, and her pierced ears. Then Amy 's mother has her sit in Penny 's closet. Title reference : The men 's bachelor party plans being ruined by the corroded bolt holding the flat tire. 187 `` The 2003 Approximation '' Mark Cendrowski Story by : Chuck Lorre & Steve Holland & Eric Kaplan Teleplay by : Steven Molaro & Maria Ferrari & Tara Hernandez October 12, 2015 ( 2015 - 10 - 12 ) 4X7204 17.96 Leonard and Penny finally tell Sheldon they have moved in together now that they are married. Sheldon is upset, but Bernadette says he should try to find another roommate, though Stuart firmly rejects her idea that he move in with Sheldon. Sheldon rejects everyone he meets and Amy refuses to live with him, as they have just broken up. Sheldon tries to pretend that it is 2003, before he met Leonard, Penny and Amy, and before he developed emotional connections to other people, fearing that Leonard and Penny, too, will eventually abandon him. For his sake, Leonard and Penny agree to split their time between apartments to be with Sheldon who begins to modify The Roommate Agreement for this purpose. Meanwhile, Stuart wants a band to play music in his comic book store for free. Raj and Howard write a filk song about Thor fighting Indiana Jones, though Emily suggests it would be better if people could dance to the music. Raj and Howard momentarily break up the band but quickly make up, playing the song at the store only to have Stuart say they should play music people could dance to. Title reference : Sheldon resets his life and his apartment back to 2003 when he was happier and unemotional before he met Leonard. 188 5 `` The Perspiration Implementation '' Mark Cendrowski Story by : Chuck Lorre & Eric Kaplan & Maria Ferrari Teleplay by : Steve Holland & Jim Reynolds & Saladin Patterson October 19, 2015 ( 2015 - 10 - 19 ) 4X7205 18.28 Howard builds a machine to add mileage to the Fitbit Bernadette bought for him to track his exercise. Leonard, however, decides that the group should become more active and they take up the sport of fencing, attending a class taught by Barry Kripke. After learning that Amy is single, Kripke wants to ask her out, which upsets Sheldon. The men go to a sports bar and encourage Sheldon to move on. Sheldon randomly asks two women out and is rejected. Stuart asks Penny, Bernadette, and Amy for advice on how to attract more female customers to his comic book store and they conclude that his creepy behavior is the problem. Amy sympathizes with him for being lonely, but turns him down when he hits on her. She also rejects Kripke after he sends her a photograph of him nude. When Leonard and Sheldon return home from the bar, they run into Amy and Bernadette, leading to a chat between Sheldon and Amy, who awkwardly exchange anecdotes on their attempts to move on. Title reference : The men getting all sweaty from exercising. 189 6 `` The Helium Insufficiency '' Mark Cendrowski Story by : Steve Holland & Maria Ferrari & Anthony Del Broccolo Teleplay by : Steven Molaro & Eric Kaplan & Jim Reynolds October 26, 2015 ( 2015 - 10 - 26 ) 4X7207 18.32 Swedish physicists are about to prove Sheldon and Leonard 's super-fluid hypothesis about the universe and the men need liquid helium to conduct their experiment first. Kripke refuses to let them use any of the university 's helium. Howard connects them to Kenny, a black market dealer, though Sheldon 's mistrust of him almost ends the deal. At the lab, Leonard and Sheldon panic about using stolen property and pay Kenny to take it back. Kripke offers to give them some of his helium if they share scientific credit with him. Instead, they pay Kenny for helium a third time and watch Ernest Goes to Jail with him because he gets along with them. Meanwhile, Stuart tells the rest of the group he has been on two dates thanks to an app on his phone. They download it on Amy 's phone much to her discomfort and make fun of the suggested men. To their surprise, a man named Dave texts Amy his thanks for the date they had last night. Amy reveals she has been on three coffee dates with men and is starting to like Dave. Title reference : Sheldon and Leonard do not have enough helium on hand to perform their experiment. 190 7 `` The Spock Resonance '' Nikki Lorre Story by : Chuck Lorre & Jim Reynolds & Tara Hernandez Teleplay by : Steven Molaro & Steve Holland & Jeremy Howe November 5, 2015 ( 2015 - 11 - 05 ) 4X7206 17.81 Wil Wheaton arranges for Sheldon to be interviewed for a documentary about Spock and Leonard Nimoy by his son Adam. Sheldon explains he admired the character of Spock from childhood for being unemotional and tried to imitate him. He brings up the autographed napkin from Nimoy from `` The Bath Item Gift Hypothesis '' that he keeps with his valuables, including the engagement ring he meant for Amy. His aborted proposal to Amy shocks Leonard and Penny who push Sheldon to admit he is feeling hurt. Sheldon lashes out, but decides to propose to Amy anyway for closure. From a distance, he sees her kiss another man, Dave, goodbye outside her apartment building. Sheldon leaves dejected. At home, he is upset Spock 's way of life is a lie, and Leonard tells him to start focusing on the real people in his life. Meanwhile, Bernadette wants to start renovating the house, though Howard protests against changing his childhood home. Calling in her father Mike, he asks why Howard does not want children. Howard reveals Bernadette to be the one resisting parenthood. Raj theorizes she fears it because Howard acts so childish. Howard says he always dreamed of being a responsible father to make up for his own abandonment in childhood. Bernadette promises to think about it. Title reference : Sheldon oscillating between his love for the unemotional Spock and his love for Amy. 191 8 `` The Mystery Date Observation '' Mark Cendrowski Story by : Steven Molaro & Eric Kaplan & Jim Reynolds Teleplay by : Chuck Lorre & Steve Holland & Tara Hernandez November 12, 2015 ( 2015 - 11 - 12 ) 4X7208 18.02 Amy has another date with Dave, so Bernadette and Penny decide to spy on her, dragging Leonard along. During the date, Dave reveals he is a huge fan of Sheldon 's scientific work. He asks her about Sheldon the entire time, greatly annoying her. As they leave, Bernadette hits Dave 's car. Initially outraged about the accident, Dave meets Leonard and is instantly starstruck. Amy ends it with Dave, who is happy to have kissed and been rejected by the same woman as Dr. Sheldon Cooper. Meanwhile, Sheldon struggles to move on without Amy, so he asks Howard and Raj to set him up with another woman since they introduced him to Amy. They post an ad on Craigslist that is filled with scientific and science - fiction brain teasers to solve for Sheldon 's contact information that night. Fifteen seconds after the deadline, a woman named Vanessa shows up, sharing many of Sheldon 's interests including physics, flags, and obscure languages. He does like her, but shuts the door on her for exceeding the time limit. Title reference : Bernadette and Penny spying with Leonard on Amy and her date. 192 9 `` The Platonic Permutation '' Mark Cendrowski Story by : Jim Reynolds & Jeremy Howe & Tara Hernandez Teleplay by : Steve Holland & Maria Ferrari & Adam Faberman November 19, 2015 ( 2015 - 11 - 19 ) 4X7209 18.19 Sheldon and Amy want to be friends and spend Thanksgiving day at the aquarium. Despite initial awkwardness, Amy honestly answers Sheldon 's questions about her dating life, and each wants the other to be happy. They fall back into their old relationship as friends. Later, Amy asks Sheldon to be his girlfriend again. Sheldon declines, since getting over her was too difficult, but wishes to remain friends. Amy hides her hurt feelings. Bernadette, Raj and Emily drag Howard to a soup kitchen to volunteer for the day. Howard hates washing dishes, but is delighted to meet Elon Musk, the founder of SpaceX. They bond over space travel. Meanwhile, Leonard and Penny prepare Thanksgiving dinner. When he realizes she does not know his birthday, he proceeds to list personal things he knows about her, but accidentally reveals knowing she hates some orange lingerie he bought her, which she only disclosed in her journal. To apologize for reading it without permission, Leonard dances in the lingerie, asking Penny to post an image on her social media as punishment. Penny refuses, but Howard, Raj, Bernadette, and Emily barge into the scene in his apartment. Title reference : Sheldon and Amy spend the day at the aquarium as friends and, afterwards, they switch roles in which of them wants to start dating again and the other just wants to remain friends. 193 10 `` The Earworm Reverberation '' Mark Cendrowski Story by : Eric Kaplan & Jim Reynolds & Saladin Patterson Teleplay by : Steven Molaro & Steve Holland & Jeremy Howe December 10, 2015 ( 2015 - 12 - 10 ) 4X7210 19.07 Sheldon is humming the melody to a song he does not know the name of, which is especially unusual since he has an eidetic memory. He spends two days obsessing over the tune and recording a log while he is still mentally sound, fearing he might be turning into a mad genius, thus annoying Leonard and Penny. Sheldon finally realizes the song is `` Darlin ' '' by the Beach Boys and that the lyrics relate to how Amy made him a better man, and rushes to her apartment. Although she is on a date with Dave, Amy realizes Sheldon loves her and they get back together. Meanwhile, Howard and Raj 's fan page for their filk band is liked by a person named Trent. They stalk Trent online and think he is very cool, deciding to go meet him in a café. However, they see him pick his nose and eat his own booger, causing them to run out. Title reference : The effects of the song stuck in Sheldon 's head which is called an earworm. 194 11 `` The Opening Night Excitation '' Mark Cendrowski Story by : Steven Molaro & Eric Kaplan & Tara Hernandez Teleplay by : Steve Holland & Jim Reynolds & Maria Ferrari December 17, 2015 ( 2015 - 12 - 17 ) 4X7211 17.23 After an iconic Star Wars - like opening credit crawl, the men are overjoyed to get opening night tickets to the Star Wars : The Force Awakens movie, which premieres on Amy 's birthday. Sheldon still wants to see it, despite Penny saying he should be with Amy. Sheldon has a dream / visitation where Arthur Jeffries ' ghost talks with him while dressed as a Jedi master, and convinces him Amy is more important. Talking over birthday gift ideas with Penny and Bernadette, he shocks them by saying he is going to have coitus with Amy to show her how much she means to him. On Amy 's birthday, Sheldon and Amy are nervous about having sex, but enjoy the experience more than they expected. Sheldon wants to do it again on her next birthday, which is fine with Amy. Arthur later appears to Sheldon again, asking for details about the sex, but Sheldon replies by discussing the movie, oblivious to Arthur 's real question. Meanwhile, the rest of the men go to the movie with Wil Wheaton, who arrives dressed as Spock in a Star Trek uniform. After the movie, the men lie back in the afterglow, much like Sheldon and Amy did. Title reference : The excitement generated by opening night for Star Wars : The Force Awakens and Amy / Sheldon losing their virginity. 195 12 `` The Sales Call Sublimation '' Mark Cendrowski Story by : Steve Holland & Jim Reynolds & Saladin K. Patterson Teleplay by : Steven Molaro & Maria Ferrari & Anthony Del Broccolo January 7, 2016 ( 2016 - 01 - 07 ) 4X7212 18.85 Penny can not find a way to make a sales call on psychiatrist Dr. Gallo. She has Leonard pose as a patient to get her in the door. Dr. Gallo disagrees with the way Leonard 's mother approaches psychology. Leonard feels great talking with her. When Penny meets her, Dr. Gallo has her question why she often acts like a mother to Leonard, along with her other anxieties, such as Sheldon. She also makes Penny feels better after their talk. Dr. Gallo gives her a prescription, but not the one Penny was supposed to sell. While Amy is at a conference, Sheldon spends the day at the astronomy lab with Raj. After they discover a medium - sized asteroid, they argue about what to name it ; Leonard suggests they name it after their girlfriends. Sheldon gets Raj to name it after Amy in exchange for any children Sheldon and Amy have being named Rajesh, even their daughters. Howard and Bernadette want to start remodeling the house and are excited when Stuart moves out, but are surprised when they find they miss him. Stuart sneaks back at night to watch them sleep. Title reference : Leonard posing as a patient to help Penny 's pharmaceutical sales 196 13 `` The Empathy Optimization '' Mark Cendrowski Story by : Chuck Lorre & Eric Kaplan & Dave Geotsch Teleplay by : Steven Molaro & Steve Holland & Saladin K. Patterson January 14, 2016 ( 2016 - 01 - 14 ) 4X7213 18.35 While Amy is still away, Sheldon has recovered from the flu, but though his friends attempt to help him, his rude behavior during his illness offends them. They decide to rent a party bus to Las Vegas to get away from him. Amy admits she, too, extended her trip to avoid him, and teaches Sheldon about empathy. After Sheldon realizes what he did was wrong, he apologizes to each of his friends in turn, but his apology to Emily goes wrong when he says dermatologists are not real doctors. When Raj tries to defend Sheldon, it leads to a fight between him and Emily. Sheldon decides not to go to Las Vegas with the group as a gesture of his regret, but sneaks onto the bus with Stuart to make amends with Emily and fix things between her and Raj. Sheldon and Stuart then leave, but the others decide to let Sheldon and Stuart go with them after all. Title reference : Sheldon trying to feel and understand empathy. 197 14 `` The Meemaw Materialization '' Mark Cendrowski Story by : Chuck Lorre & Jim Reynolds & Maria Ferrari Teleplay by : Steven Molaro & Steve Holland & Tara Hernandez February 4, 2016 ( 2016 - 02 - 04 ) 4X7214 18.29 Sheldon 's grandmother `` Meemaw '' visits Pasadena to check out Amy. Meemaw distrusts Amy due to their breakup and lets slip that Sheldon had planned to propose. Both Sheldon and Amy tell Meemaw how they make each other a better person, so Meemaw tells them that she wo n't stand in their way. Meanwhile, Raj has a debate about Frozen with Howard, attracting the attention of Claire, a bartender working on a science - fiction screenplay for a children 's film. She asks Raj to meet her for a scientific perspective on her plot. Raj wants to do this, but Howard and Bernadette warn him it could upset Emily. Raj is unsure where things are going with her, but eventually tells Claire he has a girlfriend. Claire says they can still meet as two platonic adults. However, at the meeting, Raj fantasizes about having a family with Claire. Title reference : Sheldon 's grandmother or ' Meemaw ' finally appearing after being mentioned in a number of episodes. 198 15 `` The Valentino Submergence '' Mark Cendrowski Story by : Steve Molaro & Jim Reynolds & Tara Hernandez Teleplay by : Steve Holland & Eric Kaplan & Jeremy Howe February 11, 2016 ( 2016 - 02 - 11 ) 4X7215 19.25 Leonard and Penny go out to eat for Valentine 's Day and realize that they are getting older after Penny is addressed as `` Ma'am ''. Howard and Bernadette plan on using their new hot tub and find a rabbit floating in it. After nursing it back to health and naming it Valentino, the rabbit bites Howard, who heads off to the ER for a rabies shot. Bernadette decides for the moment not to tell him that she is pregnant. Raj finally decides to break up with Emily and then calls Claire, who has just gotten back together with her old boyfriend. Emily does not take him back, sending Raj into a depression. Sheldon and Amy host their first live episode of `` Fun with Flags ''. Taking live phone calls, wherein Amy ends up speaking with Raj and Barry Kripke about their love lives, thoroughly depresses Sheldon. Amy does get Sheldon to admit their own breakup has made them a stronger couple. They are interrupted by Penny and Leonard, who barge in dressed as Cupids, throwing confetti in an effort to feel young again. Title reference : The name given to the rabbit that almost drowns in the Wolowitz hot tub. 199 16 `` The Positive Negative Reaction '' Mark Cendrowski Story by : Eric Kaplan & Jim Reynolds & Saladin Patterson Teleplay by : Steven Molaro & Steve Holland & Maria Ferrari February 18, 2016 ( 2016 - 02 - 18 ) 4X7216 20.03 Bernadette tells Howard she is pregnant. While he is excited at first, he begins panicking that he will be a bad parent. When Howard talks things over with the men, Sheldon is upset that a baby will change their social group. The others try to calm him down at a karaoke bar and come up with a possible way for him to make more money by expanding on Sheldon and Leonard 's research and patenting the idea. A drunk Sheldon says that, because he and Howard both grew up without fathers, Howard will know how important he is to his own child. Meanwhile, Bernadette meets with the women to tell them, though Leonard texts Penny beforehand. She is worried by Howard 's reaction, but Amy and Penny tell her life will be better with a child. Bernadette shocks them by admitting the baby was conceived on Sheldon 's bed. After their ideas for fun all turn out to be impossible to do because Bernadette is pregnant, the men invite them to sing karaoke with them. Howard and Bernadette soothe each other 's fears. Everyone takes turns singing about babies to Bernadette, while Sheldon is shocked to learn what happened in his bedroom. Title reference : Howard 's initially negative reaction to Bernadette 's positive pregnancy test. 200 17 `` The Celebration Experimentation '' Mark Cendrowski Story by : Chuck Lorre & Eric Kaplan & Jeremy Howe Teleplay by : Steven Molaro & Steve Holland & Tara Hernandez February 25, 2016 ( 2016 - 02 - 25 ) 4X7217 18.94 When Amy plans a birthday party for Sheldon because he made her birthday so special, he is reluctant on account of a traumatic childhood experience in which his sister 's friends lied to him that Batman was coming to his sixth birthday, thereby ruining all his birthdays thereafter. Nonetheless, he relents, and the friends hire TV 's Batman, Adam West, to attend as their present. When Sheldon arrives, he is initially happy, but quickly panics and runs into the bathroom. Penny tries to talk to him and they open up to one another. He emerges to apologize to everyone, after which Amy and all assembled share a toast in Sheldon 's honor. Sheldon is delighted to hear all the nice things said about him. They then receive a video call from Professor Stephen Hawking, who joins them in singing `` Happy Birthday to You ''. Title reference : Sheldon allows the group to experiment by giving him a birthday party. 201 18 `` The Application Deterioration '' Mark Cendrowski Story by : Steven Molaro & Eric Kaplan & Adam Faberman Teleplay by : Steve Holland & Jim Reynolds & Maria Ferrari March 10, 2016 ( 2016 - 03 - 10 ) 4X7218 18.68 Sheldon, Leonard, and Howard move forward with patenting their gyroscope idea, but are shocked to learn that, as Caltech employees, they are only entitled to 25 % of any profits, and that Howard, as a NASA employee, is not legally entitled to any profits. They reluctantly agree to sign, allowing Sheldon to write their own contract to share the money from the remaining 25 % with Howard. Bernadette is against this, as Sheldon belittles Howard every time they try to work together. When confronted about this, Sheldon agrees to make it part of the contract that he be respectful of Howard for the purposes of the patent. Sheldon also shows his generosity by stipulating that 1 / 4 of his profits will go to a scholarship fund for the Wolowitzs ' baby. Meanwhile, Emily sends Raj a belated Valentine 's gift and wants to see him again. Raj turns to the women for advice, but decides to go through with seeing her after they say he should n't. On his way there, Claire calls him to say she is now single and he should see her instead, since Emily is just manipulating him. Raj drives back and forth while talking to both women, unsure of whom he should see, before choosing Emily and ultimately sleeping with her. Title reference : The men being shocked that, to apply for a patent, they must give up most of their profits. 202 19 `` The Solder Excursion Diversion '' Mark Cendrowski Story by : Bill Prady & Eric Kaplan & Maria Ferrari Teleplay by : Steven Molaro & Steve Holland & Saladin K. Patterson March 31, 2016 ( 2016 - 03 - 31 ) 4X7219 19.24 While Leonard and Howard work in Howard 's lab, their wives join them and help with their project. After leaving to pick up more solder, the two men are invited to see a preview of Suicide Squad and decide to lie to their wives and attend. Howard spitefully texts Raj, unaware that he is in the lab with the women. Raj is ready to help the women out their husbands ' lie, but the men show up with flowers and apologize. Sheldon 's old laptop finally dies, so Amy buys him a new one. He does not want to dispose of the broken one and takes Amy to a storage facility, where he reveals that he has never thrown anything away, including clothes, broken electronics, and toothbrushes. Amy now feels closer to him. Sheldon sends her home so that he can skype with her on his new high - resolution laptop. Title reference : Leonard and Wolowitz attending the movie screening instead of acquiring solder for their experiment. 203 20 `` The Big Bear Precipitation '' Mark Cendrowski Story by : Chuck Lorre & Dave Goetsch & Tara Hernandez Teleplay by : Steven Molaro & Steve Holland & Jim Reynolds April 7, 2016 ( 2016 - 04 - 07 ) 4X7220 17.50 Amy persuades Sheldon to join her, Leonard and Penny for a weekend at a cabin in the woods. Sheldon is phobic to everything in the outdoors. After their hike is rained out, they play the game `` Never Have I Ever '', where Sheldon exposes Leonard 's extra bank account that he keeps secret from Penny. Penny gets mad, but reluctantly understands. She admits she is unhappy in pharmaceutical sales, but also does not want to go back to acting or waitressing. She resolves to stick to her job in order to be adult and pay off her credit card debt. Sheldon admits he was once arrested in a jaywalking incident, and Amy once pushed all the buttons in an elevator. Raj gets too involved in Bernadette 's pregnancy by suggesting specialists and buying a huge Costco teddy bear. Howard tells him to back off, until Bernadette gets upset and wants both him and the bear back. He returns, and the three listen to the baby 's heartbeat, though Raj gets a little too close again. Title reference : Rain disrupting the group 's weekend plans at a cabin in Big Bear, as well as Raj buying Howard and Bernadette a large teddy bear to celebrate their pregnancy. 204 21 `` The Viewing Party Combustion '' Mark Cendrowski Story by : Eric Kaplan & Maria Ferrari & Jeremy Howe Teleplay by : Steven Molaro & Steve Holland & Tara Hernandez April 21, 2016 ( 2016 - 04 - 21 ) 4X7221 18.16 As the group prepares to watch Game of Thrones at the apartment, Leonard refuses to go to Sheldon 's quarterly roommate agreement meeting and is further annoyed when Penny takes Sheldon 's side. Amy arrives and agrees with Leonard, stating her dislike of meetings regarding the relationship agreement. On the way there, Raj constantly brags about dating both Emily and Claire, annoying Howard. Stuart shows up in costume because Howard tricked him into wearing it. The group splits up, with Sheldon, Penny, Raj, and Stuart in one apartment and Leonard, Amy, and Howard across the hall. Leonard is further upset to learn Penny goes behind his back to Sheldon to get what she wants in the roommate agreement. Amy only took Leonard 's side because she is jealous of how close Sheldon and Penny are. Howard accidentally eats pistachios and has to go to the hospital after an allergic reaction. He is alright. The group compare all their scheming to the characters on the Game of Thrones series. The men later make fun of Stuart riding home on a bike while still in costume. Title reference : The group having a big argument during a party to watch a television show. 205 22 `` The Fermentation Bifurcation '' Nikki Lorre Story by : Steven Molaro & Jim Reynolds & Anthony Del Broccolo Teleplay by : Chuck Lorre & Steve Holland & Tara Hernandez April 28, 2016 ( 2016 - 04 - 28 ) 4X7222 18.13 Penny wins a wine - tasting trip at work, so everyone but Sheldon and a pregnant Bernadette joins her. Raj is still dating both Emily and Claire, but is not exclusive with either and decides to bring Claire, asking his friends not to bring up their relationship status. They meet Penny 's old boyfriend Zack, who raises the potential military applications of Leonard and Howard 's gyroscope system. This worries them, but Howard decides he still needs the money for his baby, so they move forward. Zack also flirts with Claire and questions why Raj is not more committed to her. Claire tricks Raj into admitting he is seeing someone else too. At home, Sheldon bores Bernadette with his love of trains and different types of toast, but she does enjoy a version of Dungeons & Dragons, in which her character is not pregnant and can enjoy alcohol, sushi, and hot tubs. She thanks him for a fun break from her pregnancy. Title reference : The group separates into two branches because of the wine tasting trip. 206 23 `` The Line Substitution Solution '' Anthony Rich Story by : Steve Holland & Saladin K. Patterson & Tara Hernandez Teleplay by : Steven Molaro & Eric Kaplan & Maria Ferrari May 5, 2016 ( 2016 - 05 - 05 ) 4X7223 17.22 To avoid his mother Beverly and join the guys at a special Avengers screening and Q&A session, Leonard has Penny collect her from the airport. Penny tries to bond with her but is countered with condescending or psychoanalytical remarks. Beverly offers to interview Amy, Bernadette and partners for a new book on high - achieving couples, but when Bernadette suggests she interview Penny too and Beverly retorts `` About what ? '', Penny finally explodes and expresses her feelings at the insults. Beverly admits reacting to the insult of neither being invited to her son 's wedding nor even being informed of it. Penny suggests holding a new ceremony for Beverly, and they at last bond. Sheldon hires Stuart to shop with Amy instead of him so he can keep his place in line for the Q&A event. Amy, annoyed, pays Stuart to yell at Sheldon, and rejects Sheldon 's flowers and apology delivered by Stuart. Stuart holds Sheldon 's place in line so he can apologize to Amy in person. Sheldon 's experience is finally ruined when only he is upset about a man joining friends in the line ahead of Sheldon. Title reference : Sheldon hires Stuart to hold his place in line while he apologizes to Amy. 207 24 `` The Convergence Convergence '' Mark Cendrowski Story by : Steven Molaro & Tara Hernandez & Adam Faberman Teleplay by : Chuck Lorre & Steve Holland & Jeremy Howe May 12, 2016 ( 2016 - 05 - 12 ) 4X7224 17.73 When Leonard and Penny announce their second wedding ceremony, conflict arises between Leonard 's parents Beverly and Alfred. Sheldon has also invited his mother Mary. Beverly and Mary are distant with each other, while Beverly and Alfred bicker. While the Hofstadters snipe at each other during dinner, Mary and Alfred bond over their dislike of Beverly and leave early, since they are staying at the same hotel. Sheldon and Leonard are later worried when neither parent will answer their phones that night, though Penny is amused at the thought that their parents are becoming closer. When Howard gets an e-mail from the U.S. Air Force about his gyroscope patent, he fears that the government is after him, due to negative portrayals of them in the media. Bernadette tries to convince him that he is paranoid, but Howard 's fears increase when he sees a car following them to dinner, unaware that it is Leonard and Penny. His attempt to evade them causes him to drive recklessly, and he is pulled over by a policeman for a sobriety test. Title reference : Everyone converging on the dinner before Leonard and Penny 's second wedding ceremony. '' Ratings No. Title Air date Rating / share ( 18 -- 49 ) Viewers ( millions ) DVR ( 18 -- 49 ) DVR viewers ( millions ) Total ( 18 -- 49 ) Total viewers ( millions ) `` The Matrimonial Momentum '' September 21, 2015 5.7 / 16 18.20 2.1 5.52 6.8 23.73 `` The Separation Oscillation '' September 28, 2015 5.5 / 16 18.03 2.1 5.55 5.9 20.78 `` The Bachelor Party Corrosion '' October 5, 2015 5.4 / 13 17.40 2.1 5.47 6.0 20.87 `` The 2003 Approximation '' October 12, 2015 5.4 / 13 17.96 2.0 5.07 5.9 20.03 5 `` The Perspiration Implementation '' October 19, 2015 5.6 / 13 18.28 2.0 5.51 5.9 20.20 6 `` The Helium Insufficiency '' October 26, 2015 5.7 / 14 18.32 1.9 4.85 6.3 21.18 7 `` The Spock Resonance '' November 5, 2015 5.5 / 13 17.81 2.1 5.19 5.8 20.00 8 `` The Mystery Date Observation '' November 12, 2015 5.7 / 13 18.02 2.2 4.98 5.9 19.90 9 `` The Platonic Permutation '' November 19, 2015 5.8 / 13 18.19 2.4 5.93 6.2 21.23 10 `` The Earworm Reverberation '' December 10, 2015 5.9 / 14 19.07 2.5 6.20 6.3 21.47 11 `` The Opening Night Excitation '' December 17, 2015 4.1 / 16 17.23 2.9 7.17 7.0 24.42 12 `` The Sales Call Sublimation '' January 7, 2016 5.8 / 14 18.85 2.1 5.10 5.9 20.95 13 `` The Empathy Optimization '' January 14, 2016 5.7 / 13 18.35 2.1 5.17 5.9 20.93 14 `` The Meemaw Materialization '' February 4, 2016 5.8 / 13 18.29 2.1 5.33 5.9 20.62 15 `` The Valentino Submergence '' February 11, 2016 6.0 / 14 19.25 2.3 5.78 6.1 22.03 16 `` The Positive Negative Reaction '' February 18, 2016 6.4 / 13 20.03 1.9 5.17 5.7 20.41 17 `` The Celebration Experimentation '' February 25, 2016 6.3 / 21 18.94 2.1 5.21 5.9 21.15 18 `` The Application Deterioration '' March 10, 2016 5.9 / 13 18.68 2.0 4.80 5.5 19.49 19 `` The Solder Excursion Diversion '' March 31, 2016 5.8 / 14 19.24 2.0 4.98 5.5 19.19 20 `` The Big Bear Precipitation '' April 7, 2016 5.6 / 11 17.50 1.9 5.28 5.0 18.78 21 `` The Viewing Party Combustion '' April 21, 2016 5.7 / 12 18.16 2.0 4.92 5.2 19.07 22 `` The Fermentation Bifurcation '' April 28, 2016 5.6 / 12 18.13 2.0 5.12 5.4 19.25 23 `` The Line Substitution Solution '' May 5, 2016 5.0 / 12 17.22 2.0 4.98 5.0 18.21 24 `` The Convergence Convergence '' May 12, 2016 5.4 / 14 17.73 2.1 5.24 5.5 19.96 Reception The ninth season received mixed reviews. John Doyle of The Globe and Mail criticized the humor, writing that `` The show is n't funny any more. The same tired jokes go around in circles. It 's dated and stale '', while Tom Eames of Digital Spy criticized the relationship between characters Leonard and Penny, writing that they `` certainly do n't have some passionate, Ross and Rachel - style ' will they / wo n't they ' romance, with fans dying to see them together. Even now they 're married, it 's a weirdly anti-climactic payoff - and it does n't quite feel right that they 're together. '' Ashley Bissette Sumerel of TV Fanatic wrote that `` For a rather serious season premiere, `` The Matrimonial Momentum '' is still a lot of fun ``. References Jump up ^ Fitzpatrick, Kevin ( June 9, 2015 ). `` CBS ' Supergirl ' Sets October Premiere, Plus More Fall Schedules ''. Screencrush. Retrieved June 9, 2015. Jump up ^ `` Shows A-Z -- big bang theory, the on cbs ''. The Futon Critic. Retrieved August 10, 2015. Jump up ^ `` The Big Bang Theory : Renewed for THREE More Years ! ''. March 12, 2014. Retrieved August 14, 2014. Jump up ^ Barnes, Nick ( May 14, 2015 ). `` CBS 2015 / 16 Fall Schedule : The Big Bang Theory move, new premieres & midseason shows ! ''. UnrealityTV. Retrieved August 10, 2015. Jump up ^ Rauch, Melissa ( August 5, 2015 ). `` So great to be back ! Here we go Season 9 ! @ BigBang_CBS ''. Twitter. Retrieved August 10, 2015. Jump up ^ Nayyar, Kunal ( August 5, 2015 ). `` Back to work this morning :) @ BigBang_CBS season 9 ! Let 's. Do. This. Who 's in ? ''. Twitter. Retrieved August 10, 2015. Jump up ^ Abrams, Natalie ( August 21, 2015 ). `` Spoiler Room : Scoop on Big Bang, Murder, Supernatural and more ''. Entertainment Weekly. Retrieved August 22, 2015. Jump up ^ http://www.ew.com/article/2016/01/06/big-bang-theory-june-squibb-sheldon-meemaw Jump up ^ http://www.hollywoodreporter.com/live-feed/big-bang-theory-casts-leonards-876394 Jump up ^ Shepherd, Jack ( February 6, 2016 ). `` The Big Bang Theory 200th episode : Every star set to cameo, including Adam West and Sara Gilbert ''. The independent. Retrieved February 6, 2016. ^ Jump up to : `` Monday Final Ratings : ' The Big Bang Theory ' Adjusted Up ; ' Significant Mother ', ' Life in Pieces ' & ' Penn & Teller ' Adjusted Down - Ratings ''. TV by the Numbers. ^ Jump up to : Dixon, Dani ( September 29, 2015 ). `` Monday Final Ratings : ' The Big Bang Theory ' + ' The Voice ' Adjusted Up ; ' Castle ', ' Life in Pieces ' & ' Dancing with the Stars ' Adjusted Down ''. TV by the Numbers. Retrieved September 29, 2015. ^ Jump up to : Porter, Rick ( October 6, 2015 ). `` Monday Final Ratings : ' The Big Bang Theory ' and ' The Voice ' Adjusted Up ; ' Blindspot ' and ' Castle ' Adjusted Down ''. TVbytheNumbers. Retrieved October 6, 2015. ^ Jump up to : Porter, Rick ( October 13, 2015 ). `` Monday final ratings : ' The Voice ' and ' Big Bang Theory ' adjusted up, ' Castle, ' ' Life in Pieces ' and ' Scorpion ' adjusted down ''. TV by the Numbers. Retrieved October 13, 2015. ^ Jump up to : Porter, Rick ( October 20, 2015 ). `` Monday final ratings : ' Crazy Ex-Girlfriend ' and ' Jane the Virgin ' adjusted down, ' Big Bang ' adjusted up ''. TV by the Numbers. Retrieved October 20, 2015. ^ Jump up to : Porter, Rick ( November 3, 2015 ). `` Monday final ratings : ' Supergirl ' and ' Blindspot ' adjust down, ' Big Bang Theory ' adjusts up ''. TV by the Numbers. Retrieved November 4, 2015. ^ Jump up to : Porter, Rick ( November 6, 2015 ). `` Thursday Final Ratings : ' Elementary ' and ' Mom ' adjust down considerably thanks to NFL ''. TV by the Numbers. Retrieved November 6, 2015. ^ Jump up to : Porter, Rick ( November 13, 2015 ). `` Thursday final ratings : ' 2 Broke Girls ' and CBS take NFL hit, ' Elementary ' below 1.0, ' Blacklist ' adjusts up ''. TV by the Numbers. Retrieved November 13, 2015. ^ Jump up to : Porter, Rick ( November 20, 2015 ). `` Thursday final ratings : ' Mom ' and ' 2 Broke Girls ' up even after adjusting down ''. TV by the Numbers. Retrieved November 20, 2015. ^ Jump up to : Porter, Rick ( December 11, 2015 ). `` Thursday final ratings : ' 2 Broke Girls ' and other CBS shows adjust down with NFL pre-emptions ''. TV by the Numbers. Retrieved December 11, 2015. ^ Jump up to : Porter, Rick ( December 18, 2015 ). `` Thursday Final Ratings : ' Big Bang Theory ' holds, season high for ' Mom ' despite adjusting down ''. TV by the Numbers. Retrieved December 18, 2015. ^ Jump up to : Porter, Rick ( January 8, 2016 ). `` Thursday final ratings : ' Life in Pieces ' adjusts down ''. TV by the Numbers. Retrieved January 8, 2016. ^ Jump up to : Porter, Rick ( January 15, 2016 ). `` Thursday final ratings : ' The Big Bang Theory ' and ' The Blacklist ' adjust up ''. TV by the Numbers. Retrieved January 15, 2016. ^ Jump up to : Porter, Rick ( February 5, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' adjusts up, ' Life in Pieces ' and ' Mom ' adjust down ''. TV by the Numbers. Retrieved February 5, 2016. ^ Jump up to : Porter, Rick ( February 12, 2016 ). `` Thursday final ratings : ' Mom ' adjusts up ''. TV by the Numbers. Retrieved February 12, 2016. ^ Jump up to : Porter, Rick ( February 19, 2016 ). `` Thursday final ratings : ' Big Bang Theory, ' ' Scandal ' and ' How to Get Away with Murder ' adjust up ''. TV by the Numbers. Retrieved February 19, 2016. ^ Jump up to : Porter, Rick ( February 26, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' adjusts up, ' Life in Pieces ' adjusts down ''. TV by the Numbers. Retrieved February 26, 2016. ^ Jump up to : Porter, Rick ( March 11, 2016 ). `` Thursday final ratings : ' Scandal ' adjusts up, 4 CBS shows adjust down ''. TV by the Numbers. Retrieved March 11, 2016. ^ Jump up to : Porter, Rick ( April 1, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' adjusts up, ' Scandal, ' ' Life in Pieces ' and ' The 100 ' adjust down ''. TV by the Numbers. Retrieved April 1, 2016. ^ Jump up to : Porter, Rick ( April 8, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' adjusts up, ' Odd Couple ' and ' The 100 ' adjust down ''. TV by the Numbers. Retrieved April 8, 2016. ^ Jump up to : Porter, Rick ( April 22, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' and ' Bones ' adjust up, ' 2 Broke Girls ' and ' Legends of Tomorrow ' adjust down ''. TV by the Numbers. Retrieved April 22, 2016. ^ Jump up to : Porter, Rick ( April 29, 2016 ). `` Thursday final ratings : ' Grey 's Anatomy ' and ' Big Bang Theory ' adjust up, ' Odd Couple, ' ' Mom ' and ' The 100 ' adjust down ''. TV by the Numbers. Retrieved April 29, 2016. ^ Jump up to : Porter, Rick ( May 6, 2016 ). `` Thursday final ratings : ' Big Bang Theory ' adjusts up, ' Mom ' and ' Rush Hour ' adjust down ''. TV by the Numbers. Retrieved May 6, 2016. ^ Jump up to : Porter, Rick ( May 13, 2016 ). `` Thursday final ratings : ' The Big Bang Theory, ' ' The Catch ' and ' Legends of Tomorrow ' adjust up ''. TV by the Numbers. Retrieved May 13, 2016. Jump up ^ Porter, Rick ( October 12, 2015 ). `` Premiere week Live + 7 ratings : ' Blindspot, ' ' Empire ' and ' Big Bang Theory ' score biggest gains ''. TV by the Numbers. Retrieved October 12, 2015. Jump up ^ Porter, Rick ( October 19, 2015 ). `` Broadcast Live + 7 ratings, week 2 : ' The Blacklist ' premiere joins ' Empire ' and ' Blindspot ' atop the charts ''. TV by the Numbers. Retrieved October 19, 2015. Jump up ^ Porter, Rick ( October 31, 2015 ). `` Broadcast Live + 7 ratings, week 3 : ' Quantico ' more than doubles, ' Empire ' and ' Blindspot ' score biggest gains ''. TV by the Numbers. Retrieved October 31, 2015. Jump up ^ Porter, Rick ( November 4, 2015 ). `` Broadcast Live + 7 ratings, week 4 : ' Jane the Virgin ' premiere doubles, ' Empire ' and ' Blindspot ' top charts for Oct. 12 -- 18 ''. TV by the Numbers. Retrieved November 4, 2015. Jump up ^ Porter, Rick ( November 9, 2015 ). `` Broadcast Live + 7 ratings, week 5 : ' Empire ' and ' Blindspot ' have biggest toal gains, 5 shows double ''. TV by the Numbers. Retrieved November 9, 2015. Jump up ^ Porter, Rick ( November 16, 2015 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' and ' Blindspot ' top week 6, ' Quantico ' doubles in 18 -- 49 and viewers ''. TV by the Numbers. Retrieved November 16, 2015. Jump up ^ Porter, Rick ( November 23, 2015 ). `` Broadcast Live + 7 ratings, week 7 : ' Elementary ' is still a strong DVR show ''. TV by the Numbers. Retrieved November 23, 2015. Jump up ^ Porter, Rick ( December 1, 2015 ). `` Broadcast live + 7 ratings, week 8 : ' Empire, ' ' Big Bang Theory ' and ' Quantico ' top charts for Nov. 9 -- 15 ''. TV by the Numbers. Retrieved December 1, 2015. Jump up ^ Porter, Rick ( December 7, 2015 ). `` Broadcast Live + 7 ratings, week 9 : ' Big Bang Theory ' makes the biggest gains ''. TV by the Numbers. Retrieved December 7, 2015. Jump up ^ Porter, Rick ( December 29, 2015 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' gets biggest bump of the season in week 12, 5 shows double in 18 -- 49 ''. TV by the Numbers. Retrieved December 29, 2015. Jump up ^ Porter, Rick ( January 5, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' and ' Jane the Virgin ' lead a light week 13 ''. TV by the Numbers. Retrieved January 5, 2016. Jump up ^ Porter, Rick ( January 25, 2016 ). `` Broadcast Live + 7 ratings : ' Shades of Blue ' premiere gets a good lift in week 16 ''. TV by the Numbers. Retrieved January 25, 2016. Jump up ^ Porter, Rick ( February 1, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' and ' Modern Family ' lead week 17, ' Shades of Blue ' doubles ''. TV by the Numbers. Retrieved February 1, 2016. Jump up ^ Porter, Rick ( February 22, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' gains the most, ' Vampire Diaries ' and ' Shades of Blue ' double ''. TV by the Numbers. Retrieved February 22, 2016. Jump up ^ Porter, Rick ( February 29, 2016 ). `` Broadcast Live + 7 ratings : ' How to Get Away with Murder, ' 5 other shows double in a DVR - heavy week 21 ''. TV by the Numbers. Retrieved February 29, 2016. Jump up ^ Porter, Rick ( March 7, 2016 ). `` Broadcast Live + 7 ratings : ' The Blacklist ' and ' The Big Bang Theory ' lead week 22 ''. TV by the Numbers. Retrieved March 7, 2016. Jump up ^ Porter, Rick ( March 14, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' has biggest week 23 gain, ' Jane the Virgin ' and 3 others double ''. TV by the Numbers. Retrieved March 14, 2016. Jump up ^ Porter, Rick ( March 28, 2016 ). `` Broadcast Live + 7 ratings : ' The Big Bang Theory ' and ' Quantico ' lead week 25 ''. TV by the Numbers. Retrieved March 28, 2016. Jump up ^ Porter, Rick ( April 18, 2016 ). `` Broadcast Live + 7 ratings : ' The Big Bang Theory ' and ' Empire ' lead the week of March 28 -- April 3 ''. TV by the Numbers. Retrieved April 18, 2016. Jump up ^ Porter, Rick ( April 25, 2016 ). `` Broadcast Live + 7 ratings : ' Empire ' and ' Big Bang Theory ' stay on top for April 4 -- 10 ''. TV by the Numbers. Retrieved April 25, 2016. Jump up ^ Porter, Rick ( May 9, 2016 ). `` Broadcast Live + 7 ratings : ' Empire ' and ' Big Bang Theory ' lead for April 18 -- 24, 5 shows double ''. TV by the Numbers. Retrieved May 9, 2016. Jump up ^ Porter, Rick ( May 17, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory, ' ' Empire ' and ' Blacklist ' lead for April 25 -- May 1 ''. TV by the Numbers. Retrieved May 17, 2016. Jump up ^ Porter, Rick ( May 23, 2016 ). `` ' Big Bang Theory ' tops total gains, ' Vampire Diaries ' and 9 others double in 18 - 49 ''. TV by the Numbers. Retrieved May 23, 2016. Jump up ^ Porter, Rick ( May 31, 2016 ). `` Broadcast Live + 7 ratings : ' Big Bang Theory ' finale and ' Empire ' share lead for May 9 -- 15 ''. TV by the Numbers. Retrieved May 31, 2016. Jump up ^ Doyle, John ( March 1, 2016 ). `` The Big Bang Theory now running on fumes of nostalgia ''. The Globe and Mail. The Woodbridge Company. Retrieved January 5, 2017. Jump up ^ Eames, Tom ( September 22, 2015 ). `` The Big Bang Theory season 9 premiere review : One wedding and a break - up ''. Digital Spy. Hearst. Retrieved January 5, 2017. Jump up ^ Sumerel, Ashley Bissette ( September 21, 2015 ). `` The Big Bang Theory Season 9 Episode 1 Review : The Matrimonial Momentum ''. TV Fanatic. Retrieved January 5, 2017. General references `` Shows A-Z -- big bang theory, the on CBS ''. The Futon Critic. Retrieved August 14, 2014. `` The Big Bang Theory : Episode Guide ''. MSN TV. Retrieved August 14, 2014. `` The Big Bang Theory Episode Guide ''. Zap2It. Retrieved August 14, 2014. External links List of The Big Bang Theory episodes on IMDb The Big Bang Theory : Season 9 at Rotten Tomatoes The Big Bang Theory Characters Leonard Hofstadter Sheldon Cooper Penny Howard Wolowitz Raj Koothrappali Episodes Season 1 `` Pilot '' Season 2 `` The Terminator Decoupling '' Season 3 `` The Jiminy Conjecture '' Season 4 `` The Cruciferous Vegetable Amplification '' `` The Hot Troll Deviation '' `` The Love Car Displacement '' `` The Toast Derivation '' `` The Roommate Transmogrification '' Season 5 `` The Skank Reflex Analysis '' `` The Infestation Hypothesis '' `` The Wiggly Finger Catalyst '' `` The Russian Rocket Reaction '' `` The Rhinitis Revelation '' `` The Good Guy Fluctuation '' `` The Isolation Permutation '' `` The Flaming Spittoon Acquisition '' `` The Shiny Trinket Maneuver '' `` The Recombination Hypothesis '' `` The Beta Test Initiation '' `` The Werewolf Transformation '' `` The Hawking Excitation '' `` The Stag Convergence '' `` The Countdown Reflection '' Season 6 `` The Fish Guts Displacement '' `` The Santa Simulation '' `` The Egg Salad Equivalency '' Season 7 `` The Hofstadter Insufficiency '' `` The Convention Conundrum '' Season 8 `` The Locomotion Interruption '' Season 9 Season 10 Recurring concepts `` Soft Kitty '' Related articles Awards and nominations Bazinga ( genus ) Euglossa bazinga Young Sheldon Portal Book Retrieved from `` https://en.wikipedia.org/w/index.php?title=The_Big_Bang_Theory_(season_9)&oldid=801085498 '' Categories : 2015 American television seasons 2016 American television seasons The Big Bang Theory seasons Hidden categories : Use mdy dates from May 2016 Talk Contents About Wikipedia Wikiquote Català Čeština Deutsch Español Français Italiano Português Українська Edit links This page was last edited on 17 September 2017, at 15 : 39. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: the big bang theory season 9 episode 18
Answer: The Application Deterioration"