Parallel Threads, a premise for comic strip, novel/short story or even a film/TV series
Three explorers lost in a maze of parallel universes, searching for a way home.
A concept similar to "Doorways", with some additional details such as:
A trans-parallel network of espionage and manipulation;
A central or Prime parallel, an Earth in a far flung interstellar community of almost perfect socio-political and ecological balance - a standard by which all other parallels are measured (our own Earth would probably have a rating of about 20% on this scale);
a terrorist organisation dedicated to prolonging and perpetuating war on all parallels in the hope that it will bring down Parallel Prime as well (the premise here is that all parallels are somehow linked together and disorder in one parallel will eventually spread out to others unless checked and stopped).
There may or may not be time travel involved, it's mainly parallel dimensional travel, and major events have reflections of varying degrees across all parallels, e.g. World War Two on our world caused nuclear devastation on many parallels of lower index at exactly the same time, and caused one man to lose his temper and shout obscenities on Prime.
NB: a lower index does not necessarily mean a lower tech level - indeed many industrialised parallels have lower indices than pre-industrial ones. it's all a question of ecology and balance.
Many parallels can be grouped into geographical locations, i.e.
European parallel means that the predominant world culture is essentially European (this includes white American as opposed to Native American). This could also cover parallels where the Roman empire/civilisation survives to the present day.
Aztec would imply that the Aztec and Meso-American cultures conquered Europe and Middle East, with 20th century superpowers being centred in Tenochtitlan and possibly some far eastern country like China or Japan. Another interpretation of this could be a World War Two between the Aztecs and Romans - a reflection of our World War Two
Far-eastern could mean Mongol dominance or strong Chinese/Japanese influence similar to our Earth c1200 AD.
Other parallels include dominance by the Inca empires and Great Zembabawe; and the Bantu Federation, which conquered all of Africa by 1600 and within the next 200 years extended its rule from the Andes to the Himalayas and all of Europe to the Urals.
In this multiverse there is a force of Parallel Police Officers who try to prevent trans parallel interference. The three protagonists are undercover, on the trail of terrorists who are selling high technology to low technology buyers (bad enough on our Earth, let alone across parallels!)
I have thought about using a concept similar to the Tech Level used in Traveller and many other SF role playing games. TL 0 = stone age and TL 15 = high level interstellar community. Our Earth is about TL 8/9
Technology could move faster on some parallels (Star-drive on Prime), slower (Gunpowder discovered in 1969) on others or in different directions (genetically engineered creatures performing the same function as hot-air balloons, perhaps?), but similar events would occur at similar times. The American civil war of the 1860s could be an Aztec war of rebellion, or perhaps there was a Chinese rebellion against Mongol oppressors or something, all taking place simultaneously.
Trans parallel can be handled in different ways:
The Random Gate method - only certain locations have cross links between one parallel and another, some are one way, others are two way - some are recurring, say, once every full moon, others happen only once ever, you never know where you"ll end up until you get there. Examples include Stonehenge, Pyramids, Mayan temples in Yucatàn, etc.
The Predetermined Gate. A fixed gate between say European Sector 87% and Aztec Sector 66%
The Portable Gate. A device which can be tuned to an parallel and can create a temporary gate between any parallels. Duration of, say, 2 - 12 hours.
Trans Parallel Vehicle. obviously, a vehicle with a built-in portable Gate - the ultimate in going wherever you want to go!
Possible ideas for scenarios/episodes/short stories/chapters include:
The UN peace-keeping forces are sent into Northern Ireland.
Three new countries join the United States of America - Scotland, England and Wales - Ireland becomes totally independent.
Political ntrigue and adventure in the World Senate HQ in Lahore.
China is first to land on Mars and builds a base immediately.
Rev. Dr. Martin Luther King became President of the United States in 1968 instead of Richard Nixon.
Japan builds the first atomic bomb and drops it on Pearl Harbour, another takes out Los Angeles
The British Empire expands and wipes out all other cultures and then splits into dozens of fragments out of sheer boredom.
The South won the American Civil War and formed a new nation: The Confederate States of America.
Spry octagenarian Adolf Hitler leads a guerilla war against the Ottoman Empire's invasion and occupation of Germany, circa 1970.
A military stalemate between the Axis Powers and the Allied Forces in World War Two leads to an intense cold war between Nato and Nazi Europe, leading to all-out nuclear war in 1997.
Aztec-Roman war, with tanks and subs and aircraft à la World War Two.
Dinosaurs evolve into humans (well, humanoids) and create a reptilian, as opposed to mammalian, civilisation.
Dinosaurians and Humans fight for supremacy.
A million other possibilities, a billion other parallels, all intertwined into a vast tapestry of worlds called the Multiverse.
The following list is a (small) selection of works which all deal with parallel universe concepts to various degrees, some are directly linked to time travel, others are not. (as of about May 2001)
(books and role playing games)
"Time Patrol" by Poul Anderson
"There will be Time" by Poul Anderson
"The End Of Eternity" by Isaac Asimov
"Hitler Victorious" by Greg Benford (ed.)
"Traveller" by Game Designers Workshop
"Space 1889" by Game Designers Workshop
"The Man in the High Castle" by Philip K. Dick
"Dark Mirror" [Star Trek TNG novel] by Diane Duane
"Alternate Presidents" by Martin Greenberg (ed.)
"The Ivanhoe Gambit" etc (Time Wars) by Simon Hawke
"West of Eden", "Winter in Eden", "Return to Eden" by Harry Harrison
"Stars and Stripes Forever" by Harry Harrison
"Alternities" by Malcolm Kube-McDowell
"Sidewise In Time" by Murray Leinster
"Eternal Champion" series by Michael Moorcock
"Timemaster" by Pacesetter Games
"Lords Kalavan of Otherwhen" etc by H. Beam Piper
"Needle in a Timestack" by Robert Silverberg
"Gate of Worlds" by Robert Silverberg
"Return to the Gate of Worlds" by Robert Silverberg
"Up the Line" by Robert Silverberg
"The Iron Dream" by Norman Spinrad
"The Adventures of Luther Arkwright" by Bryan Talbot
"World War in the Balance" and many others by Harry Turtledove
"Philadelphia Experiment 2"
"Evil Leaper" ["Quantum Leap" season 3]
"Revenge of the Evil Leaper" ["Quantum Leap" season3]