- Doc Brown: "Without further ado, I present to you the answer to all our problems... my time travel chamber!"
- S.S. Strickland: "It looks like a refrigerator."
- Doc Brown: "It was, once."
- — Doc unveils the time travel chamber.
The time travel chamber was a time machine, built from a 1952 Sears Coldspot refrigerator, that Emmett Brown invented in the alternate timeline where an elderly Biff Tannen traveled from 2015 to 1955 with a sports almanac, to make his younger self rich.
Doc was the silent benefactor of the Hill Valley Civic Committee, which became a secret group in 1973, with the sole purpose of stopping Biff from taking over Hill Valley. The groups efforts did very little, and led to the murders of two of their members, George McFly and Terry. He also had his stepson, Dave McFly, run out of town by the Hill Valley Police Department that Biff controlled. As all hope looked to be lost to the remaining members, Doc finished the time travel chamber.
He revealed the chamber to the remaining Hill Valley Civic Committee members on May 1, 1983. Since the only way to reliably get power was to hack into the city's power grid, the 1.21 gigawatts necessary for time travel could not be sourced. Instead, Doc cut some corners in order to allow it to function.
The 465.3 megawatt capacity of the power grid would be converted to flux capacitance energy, which would send the time traveler to the date set on the time circuits displayed on a meter inside the chamber door.
The limitations of using less than half of the energy needed to properly power the chamber meant that there was only four hours of flux energy available before the time bubble protecting the time traveler would burst. This would cause the time traveler to fade from existence in the past and reappear back in the chamber in the present.
Stanford S. Strickland recalled a time that, while he was attending Hill Valley Elementary School, Biff was going to be sent to a military academy in Idaho after assaulting other children for the third or fourth time. He remembered the date, May 16, 1946, as it was the day after he celebrated his birthday.
Doc connected the chamber to the power grid, and used his JVC camcorder to capture the moment. Stanford S. Strickland, wearing a suit that his father owned, stepped into the chamber and disappeared into the past. The remaining members of the Hill Valley Civic Committee unhooked the chamber and put it in a truck to get away before Biff realized where the blackout occurred.
Mr. Strickland arrived in the past. He walked to the school, and witnessed Biff picking on a smaller child. George McFly stuck up for the child, and Biff punched George, causing his nose to bleed. Lorraine Baines informed a senior teacher, Miss Hodges, about the bullying, just as the younger Strickland apprehended Biff, after calling him a slacker.
The elder Strickland tried to stop Miss Hodges from intervening, but he was surprised to find out that she was the one who wanted to ship Biff to Idaho, and his younger self stopped her as he believed that Biff could become a good student with the proper guidance. The elder Strickland couldn't do anything else to change things, as he was accused of being a "sex herbert" by the young Biff, and Miss Hodges thought that might be true, as he did touch her when he tried to stop her from interfering.
Devastated that he had changed his own memory as he didn't want to admit to himself that he was the reason why Biff remained in Hill Valley, Strickland walked to an alley, so he wouldn't be seen disappearing by any bystanders, and sat in a crouched position with his head in his lap until time ran out. When he returned to 1983, he was still in that position, and wouldn't respond to anyone.
A week later, the civic committee met again, commenting that no one had been able to reach Strickland since the incident, and he hadn't reported in to the school either (it's unknown which school he was working for, as Hill Valley High School burned down in 1979 and wasn't rebuilt until at least some point after 1985). He blamed himself for everything and didn't want to interact with anyone.
The committee decided that the best attempt to stop Biff would be to prevent him from being born, by stopping the wedding of his parents. The only problem was that no records were available before 1950, since everything was lost after Biff bulldozed the Hill Valley Courthouse to build his casino and hotel. Goldie Wilson realized that they would be able to determine the date by going to the Biff Tannen Museum inside Biff's casino.
Upon arriving at the museum, Doc was required to buy a cigarette and hold it in his hand, due to the museum's "smoking required" policy. He was already disgusted by the museum, but he pressed himself to go on. He learned that Biff's parents, Myra Benson and Kid Tannen (going by Thomas Tannen after being released from prison), married at the Hill Valley Church of the Heather on December 6, 1936.
Doc went back to the committee, and they developed a plan. Doc would arrive at the wedding, and object to the marriage, stating that the bride is already married to his son "Melvin", and that he thinks that she is pregnant. The committee then travels once again to the power grid, where the chamber is hooked up. Doc enters the chamber, disappearing into the past, and the city's power goes out again. This time Biff demands his gang to stop whoever is causing the blackouts.
In 1936, Doc takes a taxi to the church. He is about to object to the wedding, when he hears a baby crying. When the babysitter calls him Biff, Doc realizes he made a mistake. Myra had become pregnant earlier that year. Kid wanted her to have an abortion, but she wouldn't do it, as it was illegal, and she felt that her mother would kill her if she did.
Kid and Myra married simply for the purpose of making it seem like Biff wasn't born out of wedlock. The two parted ways immediately after the wedding, and neither parent wanted Biff. Because of this, Kid's mother, Gertrude Tannen, took custody of him. Before he left his son, Kid gave Gertrude a forged birth certificate that stated that Biff was born on March 28, 1937.
Doc planned to come up with a "Plan C" once he arrived in 1983; however, the chamber was now in BiffCo, as the other members of the committee were caught by the Hill Valley Police Department when they couldn't unhook the chamber from the power grid. Biff wanted to know what the refrigerator did, and why it took so much power. Doc refused, and was committed to Mental Ward B at the Hill Valley Hospital. Sometime prior to 1985, Doc was given a lobotomy, and was placed in permanent residency in the County Asylum.
Behind the scenes
- A refrigerator was the original idea for the time machine. Bob Gale and Robert Zemeckis changed it to a DeLorean DMC-12 due to concerns that children might attempt to copy the events on-screen, and end up locking themselves in refrigerators.