The Infinite Improbability Drive was a wonderful new method of crossing interstellar distances in a mere nothingth of a second, without "tedious mucking about in hyperspace."

It was discovered by lucky chance and then developed into a governable form of propulsion by the Galactic Government's research centre on Damogran. As soon as the drive reaches infinite Improbability, it passes through every conceivable point in every conceivable universe simultaneously. An incredible range of highly improbable things can happen due to these effects.

It was installed on the Starship Heart of Gold, and both the ship and the drive were unveiled by then-President of the Galaxy Zaphod Beeblebrox.


The principle of generating small amounts of finite improbability by simply hooking the logic circuits of a Bambleweeny 57 Sub-Meson Brain to an atomic vector plotter suspended in a strong Brownian Motion producer (say a nice hot cup of tea) were well understood. It is said, by the Guide, that such generators were often used to break the ice at parties by making all the molecules in the hostess's undergarments leap simultaneously one foot to the left, in accordance with the theory of indeterminacy.

Many respectable physicists said that they weren't going to stand for this, partly because it was a debasement of science, but mostly because they didn't get invited to those sorts of parties.

The physicists encountered repeated failures while trying to construct a machine which could generate the infinite improbability field needed to flip a spaceship across the mind-paralyzing distances between the farthest stars. They eventually announced that such a machine was virtually impossible.

Then, one day, a student who had been left to sweep up after a particularly unsuccessful party found himself reasoning in this way: "If such a machine is a virtual impossibility, it must have finite improbability. So all I have to do, in order to make one, is to work out how exactly improbable it is, feed that figure into the finite improbability generator, give it a fresh cup of really hot tea... and turn it on!" He did this and managed to create the long sought after golden Infinite Improbability generator out of thin air. Unfortunately, shortly after he was awarded the Galactic Institute's Prize for Extreme Cleverness, he was lynched by a rampaging mob of respectable physicists on the ground that he has became the one thing they couldn't stand most of all: "a smart arse".


Infinite Improbability Drive - Clip from the 2005 film

"Infinite Improbability Drive" - Clip from the 2005 film, with the Guide voiced by Stephen Fry

The Krikkit robots raided the Heart of Gold and stole the Infinite Improbability Drive, as it was the Golden Bail, part of the key to their freedom.

Side effects[]

Heart of Gold

The starship Heart of Gold, as seen in the 1980 BBC TV series, which contained the Infinite Improbability Drive.

Side effects of using the Infinite Improbability Drive include temporary (and sometimes permanent), changes to the environment and morphological structure, hallucinations, and the calling into being of large marine mammals. Known effects have included the following:

  • The creation, and spontaneous upending, of a million-gallon vat of custard
  • The transformation of a pair of guided nuclear missiles into a sperm whale and a bowl of petunias
  • Redesigning the interior of the Heart of Gold
  • Turning Ford Prefect into a penguin
  • Causing Arthur Dent to temporarily lose three of his limbs
  • Transforming the desert world of Kakrafoon into an incredibly habitable oasis during a Disaster Area concert
  • Ridding the people of Kakrafoon of their telepathy during the same concert and allowing for the discovery of Magrathea by Zaphod Beeblebrox

The first known use of the Infinite Improbability Drive was initiated by Zaphod Beeblebrox and Trillian on the starship Heart of Gold. Its major consequence was rescuing Arthur Dent and Ford Prefect from open space, at the probability of two to the power of 276,709 to one against.[1]

Other events that occurred, including those that took place at a time of abnormality, include:

  • Lots of paper hats and party balloons appeared from a hole in the universe and drifted off in space.
  • A team of seven three-foot-high market analysts came from the hole and died from a combination of asphyxiation and surprise.
  • 239,000 lightly fried eggs fell out of the hole and onto the famine struck land of Poghril in the Pansel system. This caused the one surviving man of the Poghril tribe to die from cholesterol poisoning some weeks later.
  • Arthur and Ford appeared to be at the seafront at Southend, Essex, UK and were passed by a man with five heads and the elderberry bush full of kippers.


The Infinite Improbability Drive is featured in every form of Hitchhiker's media, which includes the following:




Video game[]


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