

Broadcast on the NBC radio channel from 1950–1951, Dimension X was a Science Fiction Radio Drama aimed at adults. This Genre Anthology would air new half-hour episodes weekly. Stories would often be adapted from the top science fiction writers of the day, and many of its episodes were later recycled by its successor, X Minus One. NBC would later partner with Street And Smith, gaining the license to adapt stories from Astounding Science Fiction, giving it an edge in popularity on competing radio shows.
The series was directed by Fred Wiehe and Edward King, and spanned a total of fifty episodes (four of which were repeats). Most of the scriptwriting was by Ernest Kinoy or George Lefferts, either by adapting or creating new stories specific for Dimension X.
The entire series survives today in digital form because of the Old Time Radio Researchers, who have uploaded it to The Internet Archive
, as well as having it available for sale in their "catalog".
Dimension X provides examples of:
- 20 Minutes into the Future: In episode forty-one, an adaptation of Clifford Simak's "Courtesy" aired in 1951, humanity has colonized numerous planets, including Landro, by 1997.
- Act Break: The earliest episodes don't have any breaks for commercials, but some stop midway to advertise for Wheaties, especially during the National Wheaties Week campaign.
- Adam and/or Eve: In "Beyond Infinity", a couple named Eva and Allen are shrunk down to atomic size in order to escape some fascist thugs. They wind up colonizing an election "planet", and their descendants live for billions of years before dying off.
- Adaptational Alternate Ending: In the original "Time and Time Again" by H. Beam Piper, the transfer of the 43-year-old Allan Hartley's mind into his 13-year-old self's body in 1945 is seemingly permanent. However, when it was adapted into episode thirty-nine, the process reverses after only a few hours and the older Allan dies in both body and mind in 1975. As such, the radio version leaves it ambiguous as to whether his father Blake will succeed in being elected President in 1960 and preventing the outbreak of World War III. While he only has a vague impression of the events that the next thirty years will bring, he is determined to save his son's life. Blake also has the list of the race winners up to 1970 that Allan gave him before his mind returned to the future so that he can still raise the necessary capital.
- Adapted Out: In H. Beam Piper's "Time and Time Again", the Hartleys have a German housekeeper named Mrs Stauber, who doesn't appear at all in the adaptation, episode thirty-nine of Dimension X.
- Advertising Campaigns: Dimension X was caught up in the "National Wheaties Week" advertising campaign during the month of August 1950. Act Breaks were inserted as well as The Stinger to advertise for Americans to go buy cereal.
- Another Dimension: The Title Sequence and Signing-Off Catchphrase both claim that the stories you are listening to take place in the "world" of Dimension X, clarified in the first episode to be seeing beyond the present and into the unknown. These tales come from visions of the future instead of alternate presents.
- As You Know: In the first episode, an adaptation of Graham Doar's "The Outer Limit", before the pilot leaves, Hank Hansen wants to go over procedure one last time, to make sure everything goes right (things are very likely to go wrong, and do!), which gives the audience a chance to know what should be happening and why Steve is going to be Narrating the Obvious.
- Audience Murmurs: In episode twenty-two, based on Robert A. Heinlein's "The Roads Must Roll", there's a commotion during the emergency stop as the "roads" halt because of the strike, with indistinct shouting/screaming and sirens in the background.
- Audio Adaptation:
- Episode one is an adaptation of Graham Doar's "The Outer Limit".
- "Episode two is an adaptation of Jack Williamson's "With Folded Hands".
- Episode three is an adaptation of Kurt Vonnegut's "The Report On The Barnhouse Effect".
- Episode five is an adaptation of Fredric Brown's "Knock".
- Episode six is an adaptation of Robert Bloch's "Almost Human".
- Episode seven is an adaptation of Murray Leinster's "The Lost".
- Episode eight is an adaptation of Ray Bradbury's "The Fox And The Forest".
- Episode nine is an adaptation of Donald A Wollheim's "The Embassy".
- Episode ten is an adaptation of Robert A. Heinlein's "The Green Hills of Earth".
- Episode eleven is an adaptation of Ray Bradbury's "There Will Come Soft Rains" and "Zero Hour"
- Episode twelve is an adaptation of George Pal's "Destination Moon".
- Episode thirteen is an adaptation of Murray Leinster's "A Logic Named Joe".
- Episode fourteen is an adaptation of Ray Bradbury's "Mars Is Heaven!".
- Episode seventeen is an adaptation of Jack Vance's "The Potters Of Firsk".
- Episode twenty is an adaptation of Ray Bradbury's "The Martian Chronicles".
- Episode twenty-two is an adaptation of Robert A. Heinlein's "The Roads Must Roll".
- Episode Twenty-three is an adaptation of Graham Doar's "The Outer Limit".
- Episode twenty-five is an adaptation of Fletcher Pratt's "Dr. Grimshaw's Sanitorium"
- Episode Twenty-six is an adaptation of Ray Bradbury's "And The Moon Be Still As Bright".
- Episode Twenty-eight is an adaptation of L. Ron Hubbard's "The Professor Was A Thief".
- Episode thirty is an adaptation of E Mayne Hull's "Competition".
- Episode thirty-one is an adaptation of Robert A. Heinlein's "Universe".
- Episode thirty-five is an adaptation of Paul Carter's "The Last Objective".
- Episode thirty-six is an adaptation of Stephen Vincent Benet's "The Revolt Of The Machines".
- Episode Thirty-eight is an adaptation of William Tenn's "Childs Play".
- Episode Thirty-nine is an adaptation of H. Beam Piper's "Time and Time Again".
- Episode forty-one is an adaptation of Clifford Simak's "Courtesy".
- Episode forty-three is an adaptation of Ray Bradbury's "The Veldt".
- Episode Forty-four is an adaptation of Nelson Bond's "The Vital Factor".
- Episode forty-five is an adaptation of Frank M Robinson's "Untitled Story".
- Episode forty-six is an adaptation of Ray Bradbury's "Marionettes Inc".
- Episode forty-seven is an adaptation of Murray Leinster's "First Contact".
- Episode forty-eight is an adaptation of Ray Bradbury's "Kaleidoscope".
- Episode forty-nine is an adaptation of Robert A. Heinlein's "Requiem".
- Blatant Lies: In "Hello Tomorrow", the Director of Emotional Stability tells Lois, his fiance, that he will prevent XJ12's execution. As soon as his fiance leaves, he calls the genetic cages back and orders them to continue with the execution.
- Book Ends: In "The Man in the Moon", the episode begins with a character reciting the names and descriptions of people who had recently gone missing. The episode also ends with that character reciting the names and descriptions of people who had recently gone missing, which now includes the protagonist.
- Character Narrator: In "Nightmare", adapted from Stephen Vincent Benet's poem "The Revolt of the Machines", the main character, Samson Gurney, narrates the events of the episode and his internal thoughts.
- Chromosome Casting: In episode forty-one, an adaptation of Clifford Simak's "Courtesy", despite having more than five characters, none of them are female.
- Colonized Solar System: In the forty-eighth episode, adapted from Ray Bradbury's "Kaleidoscope", there are colonies on The Moon, Venus, and Jupiter.
- Creepy Doll: In "Perigi's Wonderful Dolls", the dolls made by Perigi are capable of independent movement and speech. They're also running a blackmail scheme by getting the dolls into homes with classified information.
- Ethnic Magician: In "The Castaways", the island natives cast a curse before killing themselves by intentionally drowning in the lagoon where the bomb is being tested. Subverted, the Polynesian "natives" are actually aliens from another planet; the lagoon is holding their spaceship and they needed nuclear power because they had run out of fuel.
- Evil-Detecting Dog: In "Perigi's Wonderful Dolls", the dog, Mr Blister, is the first one to be upset by Toto, one of the eponymous dolls.
- Fake Loud: Whenever the title is said, like in the Title Sequence, it has a reverb and echo, despite not actually being any louder than the rest of the sequence. "Dimension X!... X!... X!..."
- Fantastic Nuke: In "episode eight", an adaptation of Ray Bradbury's "The Fox And The Forest", William Travis was working on a new and highly advanced atomic / bacteria bomb in 2155 before he and his wife Susan traveled back in time to 1950.
- Fantastic Slurs: In episode forty-one, an adaptation of Clifford Simak's "Courtesy", Bat Ears Brady continually refers to the Landro natives as "Gimpoes".
- Filling the Silence: In "The Parade", the Martians are supposedly marching in silence, but the audience can hear drums and cymbals.
- Find Out Next Time: After the Signing-Off Catchphrase, the narrator would summarize next week's episode, usually written with a Title Drop involved to hint at what could happen. As this series is a Genre Anthology, such episodes were only connected by this forewarning of what was scheduled. When the episode was a rebroadcast of a previous episode, this ending was changed to reflect what the actual next episode would be. The exception is for the last episode, which announces that the series is over, but to check newspapers and radios for when new episodes would begin.
- Flying Car: In "Shanghaied" mentions "taxi-copters", implying that sometime in the future taxicabs will be replaced by flying taxis.
- Genre Anthology: Each episode is a stand-alone Science Fiction story, usually adapting from popular stories in Astounding, but stories from other publishers were also solicited.
- Incredible Shrinking Man: In "Beyond Infinity", Eva and Allen enter his father's experimental Shrink Ray to hide from the totalitarian police agency. However, time passes more quickly when you're small, so their descendants are long dead within only ten seconds.
- Let X Be the Unknown: The title piggy-backs on the imagination of alternate dimensions, these stories were all about what unknowns are in the future.
- Narrating the Obvious: In "The Parade", an announcer is describing the scene of the eponymous parade. This is normal for parades over radio, and was intended to resemble the Macy's Thanksgiving Day Parade.
- Not Using the "Z" Word: In episode two, adapted from Jack Williamson's "With Folded Hands", Mr Underhill is very insistent that his wife call the machines "mechanicals", not "robots". She points out that there isn't any difference and he counters that it makes a lot of difference in advertising.
- One-Word Title: Episode 29, "Shanghaied".
- Only Known by Their Nickname: In episode forty-one, an adaptation of Clifford Simak's "Courtesy", Bat Ears Brady's first name is never revealed.
- People Zoo: In the fifth episode, adapted from Fredric Brown's "Knock", the alien Zan conquer Earth and all the animals of the planet, including the last man and woman, are exhibited as specimens in their zoo.
- Power Echoes: During the Title Sequence, the title is given a reverb and echo. "Dimension X!... X!... X!..."
- Precap: Most episodes begin with a summary of the premise, indicating who the story is about and what the central conflict will be. Some of the time, this description includes the episode name as a Title Drop. The first episode instead describes the series as a whole, explaining the unknown future getting predicted, going directly into the story from there. This same opening is
reused for "No Contact".
- Precursors: In "The Lost Race", an adaptation of Murray Leinster's "The Lost", the titular species are an ancient race who constructed the canals on Mars and the ruined cities on Titan, Centaurus II, and Centaurus III, around one hundred thousand years ago. Their influence extended to more than a thousand planets before they mysteriously destroyed themselves. The archaeologist Mr Howell determines that the Lost Race were a race of highly evolved monkeys who were being slowly mutated by atomic energy. He concludes that they committed mass suicide as they could not stand the idea of turning into human-like creatures.
- Radio Voice:
- In episode three, adapted from Kurt Vonnegut Jr.'s "The Report On The Barnhouse Effect", the observation control is being heard over the radio, so additional distortions are added in to indicate that they're not in the room.
- In "No Contact", whenever they hear back from Earth (in the form of Charlie), the voice is distorted and fainter to indicate that the signal is weak, despite using UHF radio.
- In "The Castaways", an echo is added to the characters attempting to disarm the bomb to represent their communication by radio.
- In "The Parade", voices over the phone lines have a lower volume and very mild distortion to represent that they're on the phone. The operators are slightly louder, with a Jersey accent.
- In "The Roads Must Roll", voices over the phone are scratchy and gain a reverb to indicate that the person isn't present. They're usually preceded by varying types of buzzes to indicate a call, too.
- Recruiters Always Lie: "Shanghaied" opens by describing the recruiting posters for the Deep Space Star Runs. "Seek your future in the Stars" is the tagline quoted by the characters.
- Shrink Ray: In "Beyond Infinity", Dr Winsler has built a prototype shrinking/growing machine. Objects put into the cylinder can be shrunk down smaller than an atom. The maximum shrinkage is measured in angstroms.
- Signing-Off Catchphrase: "You have just heard another adventure into the unknown world of the future, the world of... Dimension X!... X!... X!..." After saying this catchphrase, the narrator would announce what the next episode would be and the Closing Credits.
- Theremin: The theremin is one of a number of instruments that Albert Buhrman tended to choose for the music. Its distinctive sound made radio listeners easily identify that they were listening to a futuristic Science Fiction story. When the Title Sequence was revised to include references to Astounding Science Fiction, a piano and theremin play to indicate a transition to the episode's story.
- Two-Faced Aside: In "Hello Tomorrow", the Director of Emotional Stability tells Lois, his fiance, that he will prevent XJ12's execution. As soon as his fiance leaves, he calls the genetic cages back and orders them to continue with the execution.
- World War III: In "episode eight", an adaptation of Ray Bradbury's "The Fox And The Forest", a devastating atomic / bacteriological war is being waged in 2155. William Travis says that half the world is dead and the other half is dying.
- "X" Makes Anything Cool: The title relies on the imagination of alternate dimensions, these stories were all about the unknown; what is to come and how exciting it would be.
- Year Inside, Hour Outside: In "Beyond Infinity", the subatomic world that Eva and Allen are hidden in has a different sense of time than we do in our macroscopic world. The ten seconds that pass in our world represent billions of years for the subatomic world.
- You Are Number 6: In "Hello Tomorrow", specimen XJ12 is a Mutant with a twisted leg. Because he is not "genetically perfect", he is given a label instead of a name. His name is actually Orin.