The Big Bang Theory
Actor Jim Parsons (crouching) poses with co-stars from the television series "The Big Bang Theory" (from L-R) Kunal Nayyar, Mayim Bialik, Melissa Rauch, Simon Helberg, Johnny Galecki and Kaley Cuoco-Sweeting, on his star after it was unveiled on the Hollywood Walk of Fame in Los Angeles, California March 11, 2015. Reuters/Mario Anzuoni

"The Big Bang Theory" (TBBT) cast, which includes Jim Parsons (Dr Sheldon Cooper), Mayim Bialik (Dr Amy Farrah Fowler), Kunal Nayyar (Dr Rajesh "Raj" Koothrappali), Kaley Cuoco (Penny), Kevin Sussman (Stuart Bloom), Simon Helberg (Howard Wolowitz), Johnny Galecki (Dr Leonard Hofstadter) and Melissa Rauch (Bernadette Rostenkowski-Wolowitz), will have a new episode titled "The Matrimonial Metric" that will air on Thursday, Jan. 4, 2018 in the US. It will show Sheldon and Amy secretly experimenting on their friends for their upcoming wedding.

Spoiler alert: This article contains 'The Big Bang Theory' spoilers 2018. Read on if you want to know more about 'The Matrimonial Metric.'

"The Big Bang Theory" season 11, episode 12 will show Amy and Sheldon trying to choose who among their friends would be the maid of honour and the best man. Naturally, they will turn to Science to help them decide. The engaged couple will subject their friends to secret experiments to assist them with their big decision.

Meanwhile, Penny will also reveal her real feelings about Amy. Mark Cendrowski directed this episode. Its teleplay was written by Andy Gordon, Eric Kaplan and Steve Holland. The story was written by Jeremy Howe, Tara Hernandez and Maria Ferrari.

'The Big Bang Theory' episodes: 'The Celebration Reverberation' and 'The Solo Oscillation'

The TBBT episode prior to "The Matrimonial Metric" was the sitcom's 11th episode titled "The Celebration Reverberation" which was aired in the US on Dec. 14. It showed Raj and Howard still fighting, but eventually reconciling at the bounce house in Halley's party. Meanwhile, Sheldon prepared a birthday dinner for Amy with a "Little House on the Prairie" theme. Unfortunately, they ended up having food poisoning because of it. Thankfully, they eventually recovered and were able to attend Halley's birthday party.

Leonard also felt depressed when he received his brother's Christmas card which pointed out how successful he is compared to Leonard. Dave Goetsch, Maria Ferrari and Jeremy Howe wrote the episode's teleplay. As for the story, it was written by Eric Kaplan, Steve Holland and Alex Ayers. Once again, Mark Cendrowski was the director. After "The Matrimonial Metric," "The Big Bang Theory" season 11, episode 13 titled "The Solo Oscillation" will air on CBS on Jan. 11, 2018.

"The Big Bang Theory" TV show airs in the US on Thursdays at 8-8:30 pm ET/PT on CBS. Stay tuned for more "TBBT" spoilers in 2018 featuring Sheldon, Leonard, Amy, Penny, Raj, Howard, Bernadette and Stuart.