Forward the Foundation by Isaac Asimov (1993): A continuation of Prelude to Foundation, it continues the life of psychohistorian Hari Seldon as he develops his theory to create a society to replace the crumbling Galactic Empire. Like the original Foundation, it consists of a series of interconnected stories.
Why wasn’t it published while he was alive? The first three stories in Forward the Foundation were published in Asimov’s Science Fiction Magazine prior to his death in 1992. By the time Asimov succumbed to kidney and heart failure, he had a complete, albeit unedited, draft of the book. Asimov’s third memoir, I, Asimov was also published after his death, as was a final collection of short stories and It’s Been a Good Life, a compilation of Asimov’s diaries and personal correspondences collected by his wife Janet, which for the first time revealed that he had contracted HIV from a blood transfusion a decade before his death.

Radio Free Albemuth by Philip K. Dick (1976): Nixon stand-in Ferris F. Fremont occupies the White House and has turned the United States into a police state, by inventing a fictitious group of home-grown terrorists. Science fiction writer Phil Dick finds himself the target of this new paranoia while his friend, record executive Nick Brady, starts hearing voices from an alien entity that may be God. And the entity, Valis, is prodding Brady to overthrow the corrupt commander-in-chief.
Why wasn’t it published while he was alive? Dick submitted the manuscript (under the title Valisystem A) to his editor, Mark Hurst, who sent the novel back for minor revisions. But rather than make the changes, Dick reworked the concepts into an entirely new novel, VALIS. Dick gave the Valisystem A manuscript to fellow science fiction writer Tim Powers, and eventually Arbor House acquired the rights to publish it, but retitled it to avoid confusion with VALIS. Dick’s early rejected non-science fiction works, Gather Yourselves Together and Voice from the Street also enjoyed posthumous life.

For Us, The Living: A Comedy of Customs (1939) by Robert Heinlein: Heinlein’s first novel outlines a roadmap from America’s Great Depression to a futuristic utopia. Engineer Perry Nelson experiences a bad car accident in 1939, and wakes up in the year 2086. He meets and falls in love with a beautiful woman, is reprogrammed to remove his outdated sexual mores and jealousy, and learns about the technological and social advances that have passed him by.
Why wasn’t it published while he was alive? The book was rejected by several publishers, possibly due to its depictions of nudity and sexual liberalism. Although the ideas in For Us, The Living fed some of Heinlein’s later works, he was not eager to see this early effort come to life. He attempted to destroy every copy of the book. But Heinlein did give the manuscript to at least one friend, and Robert James, a Heinlein scholar, eventually found it stashed away in a garage. And so, despite the author’s best efforts, it found its way into print.

The Salmon of Doubt by Douglas Adams (2002): The unfinished novel, collected with other Adams works in a volume of the same name, promised to be the third volume of the Dirk Gently series, but Adams was considering remaking it as another volume of The Hitchhiker’s Guide to the Galaxy.
Why wasn’t it published while he was alive? While Adams was still deciding what to do about Salmon, he suffered a fatal heart attack, and now we’re left with Eoin Colfer to give us a new Hitchhiker’s Guide.

The Last Theorem by Arthur C. Clarke and Frederik Pohl (2008): In Clarke’s final novel, 15 year-old Ranjit Subramanian achieves fame when he publishes the solution to Fermat’s Last Theorem. Meanwhile, an alien empire realizes that humans have developed nuclear weapons and decides the planet must be wiped out.
Why wasn’t it published while Clarke was alive? As Clarke was working on The Last Theorem, his health began to deteriorate. So he tapped his longtime friend, Frederik Pohl, as his collaborator. Clarke sent Pohl 100 pages of notes, only 40 to 50 pages of which contained fully written text. Even Clarke had difficulty deciphering the notes, but Pohl wrote out the manuscript, the final version of which Clarke reviewed just days before his death this past March. But Clarke offered a more direct farewell to fans in the form of his 90th birthday video:

As you probably know, options for downloading non-DRM music on the internet are sparse. Wherever possible, I've provided links to YouTube music videos to ease your pain and give you a taste of the sound. Most of these songs should be fairly easy to track down for your personal collection, if you like them enough to spend a bit of money.

Radiohead - Paranoid Android

I never thought it was possible to make a creepy, provocative, and truly genius piece of music that takes its title from a sardonic robot in a classic work of humorous sci-fi. Radiohead showed me that it was. In fact, the body of the song came to Thom Yorke after he spent a horrific night at a bar with a bunch of cokeheads: "The people I saw that night were just like demons from another planet," he revealed in an interview. If that isn't a perfect way to describe alienation, I don't know what is. And nobody knows alienation better than Douglas Adams's magnificent creation Marvin the "Paranoid Android," whose malfunctioning circuits have given him a clinical depression that's second to none. What Radiohead's expressing here is utter bewilderment at reality — the essence of science fiction.

David Bowie - Space Oddity

David Bowie just might be the most talented musician to ever have a sci-fi fixation — and if you don't believe he's got a sci-fi fixation, I urge you to give another listen to "The Rise and Fall of Ziggy Stardust and the Spiders from Mars." Seriously. (Definitely don't miss "Five Years" — inspired by a doomsday dream of Bowie's, it's a chilling bit of musical soothsaying.) 1969's "Space Oddity" was where it all started; Bowie recorded it such that its release would coincide with the moon landing, and the song shot him to stardom. Now, given that, the fact that he once played The Man Who Fell to Earth, and the fact that he can make dancing look good past the age of sixty ... are we certain he's not an alien?

Eisley - Invasion

When I clicked on the music video for this song, I thought I had accidentally-on-purpose opened an X-Files episode instead. Wide shots of foreboding forests, sinister out-of-focus figures surrounding the screen, handheld shots of an invisible menace — clearly this Texas family band has alien takeover on the brain. When they perform this song in concert, they always tell the audience to go see Invasion of the Body Snatchers; that's what I call true rockstar nerds! This is the closest to pod people music we're ever going to get, and it's fantastic.

The Byrds - Mr. Spaceman

With so much fearmongering about alien invasions, it's nice to get a dosage of good old-fashioned fascination from the people who brought us that charming cover of "Mr. Tambourine Man." After Mr. Tambourine Man came Mr. Spaceman — and just as the Byrds begged the first for a song, they ask the second, "won't you please take me along for a ride?" Anyone who's stayed up all night reading L'Engle or Clarke knows they would do the same if green lights appeared outside. We just can't help ourselves.

Jonathan Coulton - The Future Soon

Cyborgs! Talking dolphins! A robot bride! Jonathan Coulton sure knows exactly what it means to be a hopeless sci-fi geek, and he dreams that in the future "the things that make [him] weak and strange get engineered away." Don't we all. Even though this starts out as a sad story of love for a girl with bionic eyes, ultimately it's about optimism — just like the best sci-fi stories. And I have to give him points for his musical use of robotic beeps and modem sounds; clearly, like a true nerd, he understands their beauty.

Flight of the Conchords - Humans Are Dead

This song actually isn't intended for human listeners, as the New Zealand folk parody duo will point out before its performance. No, "Humans Are Dead" is a victory shanty from the future, sung by androids in robot bars everywhere after they've killed us all. It's a future in which computers are no longer overworked, elephants need have no fear of mistreatment, and, apparently, there are no stairs. You'll have to listen to the song to learn more about it — and as a bonus, you'll get to hear Jemaine Clement's machine voice and Bret McKenzie's solo in binary.

Zager and Evans - In the Year 2525

You might recognize this song from 1992's Alien³, but you probably haven't heard it since then; its predictions of the future were so dark that Clear Channel Communications included it on a list of music banned after September 11, 2001. As ever, though, this bit of forbidden art provides illuminating glimpses about the truth of human society, and it explores quite a few familiar sci-fi danger warnings. In the year 3535, for example, according to Zager and Evans, "Everything you think, do, and say / Is in the pill you took today." To musicians in the 1960s, this future probably seemed far away — but 2525 looks a lot closer from this side of the millenium.

T-Bone Burnett - Humans from Earth

Here's an interesting twist on the alien contact theme — T-Bone Burnett wrote a song for us Earthlings to play when we conquer other planets. "You have nothing at all to fear," he croons, with more than a hint of menace; "I think we're gonna like it here." The sound of the song is appropriately ominous, too ... exactly what one would imagine invading human rockstars would be like. Let's hope it never comes to that; thanks, T-Bone, for reminding us to try for the status of universal good guys.

Dan Bern - No Missing Link

If you've always thought Charles Darwin didn't give us the full story, Dan Bern knows how you feel. He's provided us all with a satisfying and sufficiently foul-mouthed answer to the question of our existence in this rock ditty of fiber optics, digital remastering, and limited access freeways. Bern has doubtless produced prettier songs — his time-travel ballad "God Said No" will moisten the eyes of even the most heartless cynic — but "No Missing Link" includes a background chorus belting out the words "genetic mutation," so it's a sure choice for any sci-fi mixtape.

Bree Sharp - David Duchovny

We've covered all of the most compelling aspects of science fiction: speculation about our future, the mystery of our own existence, the hope of our own exploration ... but we missed one, and the one we missed is the dizzying exuberance of fandom. Whether or not you've ever experienced any inexplicable lust for Agent Fox Mulder, you'll certainly be able to understand the obsession with the fantastic that lies between the lines of Bree Sharp's lyrics. Maybe we each wonder different things when we look up at the sky, but in the end we're all stargazing. And Bree, I would happily curl up under the covers and watch sci-fi TV with you anytime.

Here endeth the mixtape, at least for now. Thanks to sci-fi music enthusiasts Melissa, Heather, Becca, Stephen, Ellen, Mary, Katie, Jana, Lily, and Ken. Even with their expert help, though, I'm sure I've just scratched the surface. As always, I say: Let me know what I've missed!

The upcoming BBC radio adaptation of Long Dark Tea-Time will act, in part, as a bridge between the two series:

“There is definitely Hitchhiker’s/crossover,” explains Dirk Gently adapter-in-chief and director Dirk Maggs. “In this second series there is one particular idea from Douglas’s notes for the third [unfinished] Dirk Gently book which at one point he thought might be a Hitchhiker’s book. It’s a very simple idea that puts one of the Hitchhiker’s characters in the same universe as Dirk Gently in a way that I thought had enormous potential. In this series we find that the characters in both universes are inhabiting the same world, and I think where we’re going with this is something that actually resolves later on in Hitchhiker’s. It’s turning into a bit of a prequel!”

The radio adaptation of the novel is due to be broadcast on UK BBC Radio 4 before the end of this year.

EXCLUSIVE Dirk Gently 2 to feature Hitchhiker's crossover [SFX]

Here's a perfect example of a needless and annoying "grimly," from Bruce Sterling's story "Maneki Neko" (from The Locus Awards: Thirty Years Of The Best In Science Fiction And Fantasy):

Louise frowned grimly. "That's right, wise guy. Make jokes about it. You're involved in a malicious software attack on a legal officer of the United States. You'll see."

It's almost too obvious to point out, but "frowned grimly?" You don't think "frowned" might have worked on its own? And even "frowned" seems like surplus here.

And here's a more run-of-the-mill use, from David Weber's 2004 novel The Stars At War:

"Send it Priority One," Hausman said grimly, and settled back in his chair as the light-speed burst transmission sped across the vacuum.

The reason I highlight Weber's use of "grimly" is because it's so typical: it's often used in a military/action context. It shows us that the situation is serious, and it also shows us that Hausman is a serious guy who means business. If this were a TV show, the dramatic music would swell as Hausman settles back in his chair, but there's no music in a book. So "grimly" has to serve as Weber's orchestral sting.

At it's worst, a "grimly" overdose looks something like this passage from Wilbur Smith's historical novel The Sound Of Thunder:

"You're drunk!" She accused grimly.
"Oh foul libel! Oh monstrous untruth." Saul backed hurriedly out of range.
"All right, Sergeant." She turned grimly on Sean. "Where is it?"

You'll be shocked to learn that Mercedes Lackey is addicted to "grimly." And so are a bunch of other fantasy authors. Isaac Asimov liked him some "grimly" as well, and most collections of "classic" science fiction of the 1930s through 1960s contain a fair number of grimlys. (Grimlies?) But once you start looking for it, you find "grimly" in a lot of recent stuff as well.

Douglas Adams satirizes this style of writing in Dirk Gently's Holistic Detective Agency:

"Get it moved," he repeated grimly, and bustled grimly back through the door grimly hauling up his trousers and coat in preparation for the grim ascent.

It gives you a sort of, I don't know... a grim feeling, doesn't it?

To be fair, there's an issue of changing tastes here. According to Google books, D.H. Lawrence loved to have people speaking "grimly" and someone takes some news "grimly" in a Joseph Conrad book. And they're generally regarded as pretty good authors.

The real problem with words like "grimly," of course, is that they're a substitute for real characterization. Here's Martin Amis, discussing the wealth (ha) of character development in Michael Crichton's The Lost World:

The job of characterization has been delegated to two or three thrashed and downtrodden adverbs. ‘Dodgson shook his head irritably’; ‘ “Handle what?” Dodgson said irritably.’ So Dodgson is irritable. But ‘ “I tell you it’s fine,” Levine said irritably.’ ‘Levine got up irritably.’ So Levine is irritable too. ‘Malcome stared forward gloomily.’ ‘ “We shouldn’t have the kids here,” said Malcolm gloomily.’ Malcolm seems to own ‘gloomily’; but then you irritably notice that Rossiter is behaving ‘gloomily’ too, and gloomily discover that Malcolm is behaving ‘irritably.’ Forget about ‘tensely’ and ‘grimly’ for now. And don’t get me started on ‘thoughtfully.’

I definitely think "grimly" isn't quite as ubiquitous in science fiction as it used to be, but it still turns up way, way too often. And part of the problem is that today's SF writers grew up seeing it everywhere. So it's part of their familiar vocabulary, cozy and soft like an old sweater. And it is a quick and dirty (so, so dirty) shorthand for character and action, and a certain suspenseful mood.

Plus it's sort of a "space adventurer" sort of word — it's emotional but stoic. You can have any emotion grimly, and it becomes more serious and muted, yet also more important, than a regular emotion. It's got the power of grimly!

Here's a list of fairly recent SF writers who have used "grimly" pretty recently:

• Charles Stross (although mostly in his fantasy writing),
• John Scalzi (in Old Man's War and The Last Colony),
• Richard K. Morgan (in Altered Carbon),
• Greg Bear (in many many works),
• David Brin (including the great sentence "'That wasn't me,' Beta assured grimly."),
• Cory Doctorow (including a "smiled grimly"),
• John Shirley (including "Satan chuckled grimly" in his Constantine novelization),
• John Varley (but not since 1983's Millenium),
• Connie Willis (a lot),
• Orson Scott Card ("laughed grimly," "smiled grimly," and the phrase "grimly determined" appears in two different books.)

The sprawling saga that loses the thread is a more common problem in fantasy books than in science fiction — think the Robert Jordan's Wheel Of Time, or Marion Zimmer Bradley's Darkover books. But science fiction still has its own never-ending stories that really ought to end. Here are the biggest problems:

Changing the rules: When I first read To Your Scattered Bodies Go by Philip Jose Farmer, I was incredibly excited by its story of an artificial planet where everybody who's ever lived comes back to life. Until I got to the end of the book and realized it was actually Book One in a long series, and none of my nagging questions about the resurrection planet, Riverworld, would be answered for another three or four books. I was even more annoyed when a friend of mine told me that Farmer changes the rules of Riverworld after the first book, to make it easier to keep spinning out tales. I think there my have been some book-throwing involved.

The heir apparent. As I mentioned, a reviewer coined the term "Herbert's Syndrome" in 1984, when Frank Herbert was still alive and had yet to publish his sixth Dune novel, Chapterhouse: Dune. The reviewer defined it as when "a large advance induces a good writer to extend a successful series beyond its natural span." You may have your own opinions about whether six Dune books were too many — but since Herbert's death, his son Frank and his collaborator Kevin J. Anderson have already written seven Dune books, with more on the way. Say it with me: "The cash must flow."

The neat trilogy that becomes a messy tetralogy, and more. The first two Hitchhiker's Guide To The Galaxy books by Douglas Adams seemed pretty well-rounded, encompassing more or less the same arc as the original radio series and TV series. So I was a little nervous about the third book, Life, The Universe And Everything, but it was still a fun ride and seemed to move things forward. I was less thrilled by the fourth volume in what Adams called "the increasingly inaccurately named Hitchhiker's trilogy." So Long And Thanks For All The Fish, felt sort of anemic, as if Adams really didn't have any more ideas for the series, but he needed the Ningis. And then I think I read the fifth volume, but I have no memory of it whatsoever.

The need to explain the meaning of everything. Feminist science fiction blogger Liz Henry says this is where many series break down:

People write a series, and then they feel the need to finish it off and Explain it and they go all mystical and metaphysical. [They] try to solve every giant Burning Issue of Existence and good and evil, and why does the universe exist at all, and [the meaning of] utopia. So often, you get the underlying Manifesto or attempt to come up with a coherent philsopy of the author, but all too often, you sure wish they hadn't. By the time Herbert hits God Emperor of Dune, he has gone compeltely mad, trying to explain Everything, and there is no plot any more.

The random left turn. Isaac Asimov gave into fans' pressure, after a thirty-year gap, and started writing more Foundation novels again. And few would argue that Foundation's Edge or Foundation And Earth are in the same league as the original trilogy. One major problem: a slew of new characters, including one who's introduced right at the end of Foundation And Earth, who might have played a bigger role in a final Foundation book, had Asimov written one. But in the end, it just feels as though Asimov is floundering a bit, in the unnecessary sequels.

The miraculous save. In Suzette Haden Elgin's Native Tongue series, there's a clan of women and children who become language experts, and learn a ton of alien languages so they can serve as translators. But over time, they create their own secret language that the men don't understand. Which is great, but then in the third book, suddenly the women discover that they can eat sounds. They can survive by ingesting noises — sort of like a plant's photosynthesis, except noisier.

The shrinking protagonist. Harry Harrison's Stainless Steel Rat books become less and less fun, as his roguish protagonist, Slippery Jim DiGriz, becomes more and more of a pussycat. But worse yet is when we get a new protagonist whose story cheapens our original hero, like Bean in Orson Scott Card's Ender's Shadow.

To be fair, why shouldn't novels go on and on and on? It's what movies do, with their endless sequels. And TV series — who really thinks Smallville deserves an eighth season? On the other hand, the thing that makes novels superior to other media is the fact that they have a single author, who puts his/her stamp on them. When that one person runs out of ideas, the novels themselves start to deflate.

With TV, movies, comics and other media, as long as the corporate copyright-holder can find another Akiva Goldsman or Roberto Orci to spin out a new idea, you can have endless installments. In theory, no TV series ever needs to go stale, as long as the writers have the grace to leave when they run out of ideas. (Which almost never happens.) It's a bit harder with books though — and I like picking up a novel and discovering a new universe for the first time.

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• The Holtzman Effect: In the Dune series, the spice melange was able to increase your lifespan, heighten your senses, and let you see safe paths through the space-time continuum. Of course, in order to use this last benefit, you had to live in a micro-gravity environment while being constantly saturated with spice. Plus, it would mutate your body into something fairly hideous. However, in order to actually fold space and make this travel happen, you'd need a Holtzman Drive, which used subatomic energy fields to fold space and let you travel over vast distances in the blink of an eye. Without a navigator, you might not make it to your final destination.
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• The Infinite Improbability Drive: In order to get around traveling over the enormous distances in space, Douglas Adams created this drive in The Hitchhiker's Guide to the Galaxy to avoid "all of that tedious mucking about in hyperspace." It was invented by a student who was sweeping up after a party, and decided that if such a machine was a virtual impossibility, then it had to logically by a finite improbability and went from there. Basically, when you activate the drive (which is an electronic brain hooked up to a Brownian motion generator... like a cup of tea) it causes you to pass through every point in the universe at exactly the same time. Then you just drop down the improbability levels, and hope you come out where you need to be.
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• The Stargate: In the universe of Stargate, you can travel over huge interstellar distances simply by stepping into the giant Stargate, and popping out on the other side where another giant gate exists. You could select which gate you wanted to travel to by dialing a "code" on the gates and locking the nine different chevrons into place. They were constructed as a network by a race of ancient alien beings, and basically open up wormholes for travelers to jaunt through.
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• Jaunting: In Stephen King's short story "The Jaunt" (found in the Skeleton Crew anthology) the technology exists to teleport people over huge distances. However, you have to be put to sleep for the trip, and revived on the other end. If you travel through while awake, very bad things happen. In fact, they send a convicted murderer through while awake, in exchange for him getting a full pardon. When he comes out the other end, he mutters "It's eternity in there" and then dies of a massive heart attack. In the story, a father tells his children about these bad things, and of course the son holds his breath when they hose them down with sleeping gas, so he can see what it's like. It ain't very pretty.
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• Artificial Black Holes: In the movie Event Horizon, the ship (of the same name) creates artificial black holes by using a gravity drive, and this allows them to fold space in order to travel large distance quickly. As usually happens with a technology like this, something goes wrong along the way. In this case, the ship literally ends up in hell, and seems to become possessed by an evil entity. Everyone goes a little bit nuts, Sam Neill tears his own eyes out, and that's about enough to make you not want to try out this method of travel.
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• Cryogenic freezing/sleep: In Alien and countless other science fiction books/movies, travelers often enter a suspended animation hypersleep so they don't go insane from space madness when their trip takes 40 years to complete. The downside is, everyone else you know in the world will continue aging at a normal rate, while you're frozen in place. This is why all of Ripley's friends and her daughter were dead once she was found drifting in Aliens some 57 years later. This doesn't mean that the ship you're in will be traveling faster than the speed of light, but when you wake up on the other side it'll feel pretty instantaneous, which is what really matters.
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• The Wave Motion Engine: Whether you know it as Starblazers, or under the original title Space Battleship Yamato, they both traveled the same way via the Wave Motion engine. This enormous device powered the entire ship, allowed them to fire the Wave Motion Gun, and also had to ability to make them jump quickly through space using tachyon energy. Since they had to travel 148,000 lightyears to bring back a device that would cleanse the earth of deadly radiation, this came in pretty handy. However, this could not be used constantly, since both the place of origin and the destination had to be locked in "phase," and if this wasn't done correctly the ship could destroy the universe.
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• FTL Drives: In the world of Battlestar Galactica, the ships of the colonial fleet and the Cylons alike both travel over large distances by using FTL drives. While a bit of a misnomer, since the ship actually teleports instantaneously rather than rocketing at speeds great than the speed of light (a la Star Trek) to a new destination, it still has the desired effect. The process by which this works is not actually discussed on the show, but we do know that the drives are powered by the ore Tylium, and that ships can even jump out of a planet's atmosphere. The constantly jumping episode "33" shows just how much they rely on this technology, and how the Cylons use it to stay a step behind, or a step ahead in some cases.
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Baio writes:

From an anonymous source close to the company, I've found myself in possession of the "Infocom Drive" — a complete backup of Infocom's shared network drive from 1989. This is one of the most amazing archives I've ever seen, a treasure chest documenting the rise and fall of the legendary interactive fiction game company. Among the assets included: design documents, email archives, employee phone numbers, sales figures, internal meeting notes, corporate newsletters, and the source code and game files for every released and unreleased game Infocom made.

We also learn that the software infrastructure of the game might have actually become a character in the game itself. Designer Stu Galley wrote in an email:

I've been talking with Tim Anderson about using the New Parser in this game. It still needs a lot of development, and in the end it may prove to be slow in operating, but it promises to be very capable. Now here's the question: should the game itself make a big deal out of the New Parser? For example, the game could begin with the parser introducing itself to the player, asking the player to type a few sentences to "warm up" the parser, before getting on with the story itself. The parser could take on a personality, explaining that this is its first job, that it means well but it may not succeed. Perhaps it gets depressed and refuses to work at all. Perhaps the parser is in fact Marvin's new aural interface module, depressing him even further.

Time Cop. Jean-Claude Van Damme is the only one who can safeguard history against those who would change it for their own evil ends. But a corrupt U.S. Senator (Ron Silver) is messing with the timeline in order to become president in 2004. Van Damme quickly figures out what's going on. But then Silver changes history some more, so when Van Damme returns to his present, everything has changed and Van Damme no longer has a job. It's up to Jean-Claude to go back once again and change the past a second time, getting rid of Silver in the process. Weirdly, this is one of the best movies about time travel in spite of its action-movie star.

(Versions of Van Damme's Time Cops show up a lot in SF, including the ChronoGuard in Jasper FForde's Thursday Next novels, and the temporal police from the 29th century, who show up in Star Trek: Voyager a few times. Stephen Hawking has famously theorized that some kind of temporal police must exist, to prevent the horrendous paradoxes that would otherwise happen. In Ken MacLeod's Newton's Wake, they're referred to as the "Quantum Angels.")

Primer. Abe and Aaron create a time machine, which requires you to lay inside it for as long as you want to go back for. They go back and start meddling with their own pasts, speculating on the stock market and tinkering with other things. But soon they're making more serious changes — knocking out their past selves and taking their places. They live through the same day or two over and over again, creating alternate timelines with subtle differences each time. Eventually, Abe and Aaron start trying to counter each other's interference, but keeping up with which version of Abe or Aaron you're seeing gets trickier and trickier.

Back to the Future Part 2. When "Doc" Brown carelessly leaves his Delorean time machine unguarded, that big lunkhead Biff goes back in time to 1955 and gives his younger self the means to become rich and powerful far beyond his pathetic dreams. Our hero, Marty, has to go back in time to 1955 for the second time in a row — except instead of changing Biff's future as he did in the first movie, he's just trying to undo the changes that Biff has already made.

Up the Line by Robert Silverberg. Jud Eliott III gets a job as a time courier, showing tourists the wonders of history. But some of his crazy colleagues start messing around with the timeline and wrecking history, so he has to keep going back and trying to fix the damage without attracting the attention of the Time Patrol. And then he falls in love with a time paradox named Pulcheria, his own great-great-great-great-grandmother, and it all goes to pot.

The End Of Eternity by Isaac Asimov. Harlan belongs to a time agency called Eternity, which exists outside of time itself. He and his fellow agents go around changing history to reduce human suffering. But then Harlan has a falling-out with his bosses over his girlfriend Noÿs, whom they want to erase from history. Harlan is supposed to help one of his colleagues, Cooper, go back to the 24th century and become the scientist whose discoveries later make the Eternals possible. In a fit of pique, Harlan sends Cooper back to 1932 instead, so he can't lay the groundwork for Eternity and Eternity will never exist. Finally, after the Eternals un-erase his girlfriend, he agrees to go back and rescue Cooper from the past — but then his girlfriend Noÿs reveals that Eternity's secret purpose is to edit history to make sure humans never colonize the stars. So instead Harlan helps her to change history so that humans discover atomic energy earlier, and start down the path of space exploration. As a consequence, Eternity ceases ever to have existed.

Lightning by Dean Koontz. Laura has a guardian angel who shows up to help her whenever she's in danger, but then it turns out other people are trying to undo the "angel's" work. Some evil Nazi time travelers are trying to destroy Laura. As Laura's son explains:

They can hopscotch around us.. They can pop ahead in time to see where we show up, then they pick and choose the easiest place along the time stream to ambush us. It's sorta like... if we were the cowboys and the Indians were all psychic.

Doctor Who. For a show all about time travel, Doctor Who doesn't have that many stories where the Doctor and another time-traveler are both changing the timeline back and forth, surprisingly. But the Doctor and his fellow Time Lord the Master get into some duels on a few occasions. The most over-the-top is in the comedy special "Doctor Who And The Curse Of The Fatal Death," where the Master and Doctor meet up in a castle. The Master goes back in time and bribes the architect to put a trapdoor right where the Doctor happens to be standing. But then it turns out the Doctor also went back in time, and bribed the architect even more — to put the trapdoor where the Master is standing instead.

Dirk Gently's Holistic Detective Agency by Douglas Adams contains a lot of cris-crossing back and forth in Reg Chronotis' time machine (much of which is lifted somewhat from the episodes Adams wrote for Doctor Who. In particular, the ghost of the last surviving Salaxian possesses a disgruntled literary magazine editor, inspiring him to go back in time to repair the Salaxian spaceship before it can explode, back at the dawn of life on Earth — which will have the effect of making sure life never develops on this planet. The instructions for fixing the ship are buried in the second half of Coleridge's poem "Kubla Khan." But Chronotis and Dirk Gently, our detective hero, go back to Coleridge's time and ensure he never finishes that poem, so the instructions are lost and the alien plot is foiled.

Terminator. The Terminator movies and TV show are all about people and cyborgs traveling back in time to change, or safeguard history. The machines want to kill Sarah Connor before she can ever give birth to future resistance leader John Connor, so John sends Kyle Reese back in time to protect him — and Kyle becomes John's daddy. And then, the machines send more cyborgs back to kill John, and eventually Kyle's brother Derek ends up back in our time hanging out with his friend/nephew as well. And Sarah Connor either dies of cancer or travels forward in time past her own death date and somehow avoids it. Maybe in the second season of Sarah Connor Chronicles the machines will figure out they just have to wipe out the Reese brothers as kids, and all their problems go away.

Time After Time. H.G. Wells and Jack The Ripper battle each other in the bizarre future of 1979. Once they both reach the future, time travel doesn't play that much of a part in the story — except that at one point, Wells travels forward in time three days with his girlfriend Amy, only to find Amy's obituary in a newspaper. They have to travel back again and prevent Jack the Ripper from making Amy his fifth victim. (In the end, it turns out the obituary was mistaken, and it was Amy's friend who was murdered.) And then Amy goes back to the 19th century and marries Wells, changing history at least somewhat.

Meet The Robinsons. An animated Disney film, very loosely based on the book A Day With Wilbur Robinson. Tom Selleck invents a time machine. (We'll just pause to let you absorb that piece of info.) And then a villain named Bowler Hat Guy travels back in time to sabotage a memory-scanning machine that a kid named Lewis has invented, which gave rise to all the amazing inventions in Tom Selleck's utopian future. ("Tom Selleck's Utopian Future" will be my next band name.) So Tom Selleck's son Wilbur has to travel back in time to our time, to make sure Lewis repairs the memory-scanning machine.

Crime Traveler. In this British TV series, a physicist named Holly Turner invents a time machine, and a lazy detective named Slade uses it to travel back in time and solve crimes before they happen. But in the final episode, a criminal gets his own time machine, and travels back in time to give himself an airtight alibi for a couple of murders. Slade has to travel back as well, to catch the other time traveler in the act.

Research by Nivair Gabriel

• Frak, Battlestar Galactica: Whether you spell it frack or frak, it's currently the most used replacement for the f-bomb, courtesy of the original BSG show. That's right, Ronald D. Moore didn't invent this sucker, although he sure uses it a lot more than they did back in the 1980s. Plus it rolls off the tongue nicely. Here's a video education on all the uses it has.

  

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• Frell, Farscape: Frell was Farscape's own version of everyone's favorite f-word, and used extensively on the show after appearing in the first season. "Frell Me Dead" has become a favorite phrase among fans of the show, appearing on shirts and wristbands, and they even use the term "frellwit" on the show. Pretty frelling cool.
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• Gorram, Firefly: Firefly had a whole new language of swears due to the fact that Joss Whedon assumed that in the future Chinese and English would meld together, and that's led to some colorful swears for the show, like "Ching-wah tsao duh liou mahng" translated as "frog-humpin' bastard." However, gorram strands out as a simple perversion of goddamn, and probably made the most appearances on the show.
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• Shazbot, Mork & Mindy: While it never quite caught on in pop culture, Mork's substitute for shit still exists in the Tribes video games. Robin Williams probably made this word up himself, and it has the bonus of sounding like something a robot might do on your carpet.
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• Poodoo, Star Wars: George Lucas' prequels not only gave us bad acting, but it included fart jokes and this word for Bantha shit in Episode I. Which helps give you a single word to sum up the prequels with.
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• Smeg, Red Dwarf: Lister's favorite swear word from this trapped in space show obviously seems derived from smegma (wiki it if you're not informed), but series creator Grant Naylor claims he never knew that word when he wrote in smeg. He just thought it sounded like a future curse word. As Lister would say, "Whatever, you smegging smeghead."
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• Farathoom, Don't Bite The Sun: Tanith Lee's 1976 novel was full of hedonistic pleasure domes, mutable appearances and genders, and new swear words. Farathoom was probably the strongest, meaning "bloody fucking hell," although "floop" meant "cunt." We're not sure which one is cooler.
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• Shock, Spiderman 2099: Marvel Comics went on a tear in the 1990s, offering up versions of their classic characters in the year 2099. My favorite was Miguel O'Hara as the semi-mutated version of spiderman, who frequently would yell "What the shock?!" when he would be attacked by Venom 2099.
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• "I seem to be having tremendous difficulty with my lifestyle", The Hitchhiker's Guide to the Galaxy: Arthur Dent utters this phrase, just as a freak wormhole opens up in the space-time continuum, and it ends up triggering a massive interstellar war because in the Vl'hurg tongue this was the most dreadful insult imaginable. Just to encourage you to watch your language out there.
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• Smurf, The Smurfs: It just occurred to me that since Gargamel created Smurfette in his home laboratory, she's got herself a quasi-spot in scifi. Couple that with the fact that the Smurfs use "smurf" as a verb, noun, adjective, and everything else under the sun, and probably more than one Smurf has banged his thumb with a hammer and yelled out "SMURF!" Or if Jokey Smurf leaves an exploding box in your house, you'd probably tell him to Smurf Off.
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Arthur Dent visits the "factory floor" where his new friend Slartibartfarst creates custom-made planets. You can see partially completed planets in the distance, but there's a whole planet scrolling underneath their little space trolley. Douglas Adams' imagination finally gets a worthy canvas. It's one of the few memorable moments in the movie, which managed to turn the sparkling wit of Hitchhiker's into a bland soap opera.

Famous names: Created and written by Douglas Adams.

Crunchy goodness: 3

Spinoffs/Sequels/Copycats: It's taken many forms, all of Adams worked on: a radio show, books, a record, a text-based video game, stage productions, and a big-budget Hollywood film (whose existence is justified by the expression on Arthur Dent's face from 1:22:48 to 1:22:53).

Design breakthrough: The pages of the computerized Hitchhiker's Guide were created via animation designed to resemble wireframe computer graphics; then and now, actual computer graphics would be lucky to look as good.

Deadliest spoiler: What the hell is a digital watch, and why would you need both hands to operate it?

BBC Guide to the Hitchhiker's Guide