First, go to The Tough Guide to the Known Galaxy and read the entry "FUTURE HISTORY". The read the TV Trope's Standard Sci-Fi History (you might also want to read the TV Trope's Standard Sci-Fi Setting. Hackneyed, formulaic, derivative, and space opera; but very common).
Also check out this website's historical timeline of (mostly) real world events.
The 1950's flavored future history below is sort of an amalgam of Donald A. Wollheim's "Consensus Cosmogony", TV Trope's Standard Sci-Fi History, and my own memories of reading 1960's era science fiction.
Novels that cover several of the following stages include THE REDISCOVERY OF MAN by Cordwainer Smith, BIRTHRIGHT: THE BOOK OF MAN by Mike Resnick, and the anthologies GALACTIC EMPIRES vol. 1 and vol. 2 edited by Brian Aldiss.
Initial voyages to Luna and the planets of the solar system. Stories of the first efforts to set up terrestrial bases on the planets. Stories of the first colonies on such worlds, their problems internal and external, their conflicts with the parent world (maybe even a war of independence), interplanetary commerce, spaceship trade lanes, space pirates, asteroid mining, the weird wonders of the Outer Planets. Examples: TALES OF KNOWN SPACE by Larry Niven, SPACE CADET, FARMER IN THE SKY, THE ROLLING STONES, THE MOON IS A HARSH MISTRESS, PODKAYNE OF MARS, BETWEEN PLANETS, "Logic of Empire" by Robert Heinlein, SPACE DOCTOR by Lee Corey, HIGH JUSTICE, EXILES TO GLORY, "Tinker" by Jerry Pournelle, LIFEBOAT aka DARK INFERNO by James White, SCAVENGERS IN SPACE by Alan E. Nourse, THE MARTIAN WAY by Isaac Asimov, HIGHER EDUCATION by Pournelle and Sheffield, ISLANDS IN THE SKY, THE OTHER SIDE OF THE SKY by Arthur C. Clarke.
First interstellar flights. Starships that must travel centuries and contain generations descended from the original crews. Other planets of other stars. Contact with Terra is difficult at best. Lost colonies are typically founded during this era. Ben Bova calls this the "Marco Polo" stage of interstellar contact: adventure, strange tales, and artifacts. But no lasting political relations (for better or worse) with the neighbors. Example: TAU ZERO by Poul Anderson, ORPHANS OF THE SKY, TIME FOR THE STARS by Robert Heinlein, THE STARS ARE OURS by Andre Norton, THE OUTCASTS OF HEAVEN'S BELT by Joan Vinge, THE SONG OF DISTANT EARTH and RENDEZVOUS WITH RAMA by Arthur C. Clarke.
Forrest J. Ackerman calls it "atomigeddon". Widespread nuclear death on Terra. Fall of civilization. Mutants. Political map is wiped clean, most or all modern day nations are gone. Eventual recovery. Example: A CANTICLE FOR LEIBOWITZ by Walter Miller, LOT and LOT'S DAUGHTER by Ward Moore, DAVY and STILL I PERSIST IN WONDERING by Edgar Pangborn, the Hiero Desteen series by Sterling Lanier, VAULT OF AGES by Poul Anderson, DAYBREAK - 2250 A.D. aka STAR MAN'S SON by Andre Norton.
First Contact. Intelligences on extra-solar planets and our problems with them or against them. What happens depends upon whether the aliens technology level is lower, the same, or greater than humanity. And whether the aliens are friendly or hostile. Things can range from alien invasions to humans playing star-god with primitive aliens. Examples: THE MOTE IN GOD'S EYE by Niven and Pournelle, "First Contact" by Murray Leinster.
As per #2, but quicker. Examples: VOYAGE OF THE SPACE BEAGLE by A.E. van Vogt, THE LEGION OF SPACE or THREE FROM THE LEGION by Jack Williamson.
Human colonies on other solar systems. Contact with Mother Terra, independence or dependence. Commerce - exploitation or otherwise. Go to The Tough Guide to the Known Galaxy and read the entry "COLONIZATION". Example: THE STARS LIKE DUST by Isaac Asimov, THE STAR FOX and THE ENEMY STARS by Poul Anderson, THE SEEDLING STARS by James Blish, REVOLT ON ALPHA-C by Robert Silverberg, the Med Service series by Murray Leinster, THE GREAT EXPLOSION by Eric Frank Russell, the Humanx Commonwealth series by Alan Dean Foster.
The history can go through the Cycle of Empires one or more times.
The rise of contact and commerce between many human-colonized worlds or many worlds of alien intelligences that have come to trust and do business with one another. For whatever reason the indepenent human and/or alien worlds unite. This can be for common defense, cultural reasons, economic reasons, or by conquest. The problem of mutual relations and the solution, usually in the form of treaties or defensive alliances. Implacable aliens in the cosmos who must be fought. The need for defense. The rise of industrial or financial or political powers, the eventual triumph of one and the establishment of a federation, a union, an alliance, or an autocratic empire of worlds, dominated usually from Old Terra. Example: the Trantorian Empire novels of Isaac Asimov, the Nicholas Van Rijn novels of Poul Anderson, THE HELMSMAN by Bill Baldwin, CITIZEN OF THE GALAXY by Robert Heinlein, THE WITCHES OF KARRES by James Schmitz, THE REDISCOVERY OF MAN by Cordwainer Smith, BIRTHRIGHT: THE BOOK OF MAN by Mike Resnick.
Commerce between worlds an established fact, and adventures while dealing with worlds in and out of the Empire. The Pax Galactica reigns — a long period of peace and prosperity (at least on the surface). Technology is highly advanced. Civilization at it apex. During the Dark Ages, people will look back to this time as the Golden Age. The farthest planets, those of the Galactic Rim, considered as mavericks. The problem of aliens again outside the Empire, and outside our own galaxy. Politics within the government setup, intrigues, and dynasties, robotic mentalities versus human mentalities. Terraforming worlds for colonization. The exploration of the rest of the galaxy by official exploration ships (from the Survey Service), or adventurers, or commercial pioneers. Authors tend to avoid writing stories set in this period because it is very boring. Examples: The Lensman series by E.E. "Doc" Smith, FEDERATION by H. Beam Piper, the Commodore Grimes series by A. Bertram Chandler, the Sector General novels by James White, THE REDISCOVERY OF MAN by Cordwainer Smith, BIRTHRIGHT: THE BOOK OF MAN by Mike Resnick, the "First Empire" mentioned as background in THE MOTE IN GOD'S EYE by Niven and Pournelle.
This period varies depending upon the iteration, whether this is the First, Second, or latter Galactic Empire. The first is the most optimistic period. The Second Empire is generally wiser and more benevolent, but is also aware that empires can fall. In the Golden Age, the Second Empire was often also the Final Empire. Third and later empires are essentially the same setting as the Second Empire, but the higher number serves to imply an old galaxy, not locked in stasis.
If this period doesn't turn out to be the Final Empire, eventually the edifice begins to crack, leading to:
Empire begins to decay. Intrigue and palace revolt. Breakaway planets. The alliance of worlds strained beyond its limits by rebellion, alien wars, decadence, corruption, scientific inability to keep up with internal or external problems. The rise of restless subject worlds. Outer provinces begin to revolt. Rim barbarians begin to invade. Decline, then loss of contact with farthest worlds, crumbling of commerce, failure of space lanes, distrust, finally worlds withdrawing into themselves as the empire/alliance/federation/union becomes an empty shell or is destroyed at its heart. Since Isaac Asimov showed the way, this period will resemble Edward Gibbon's Decline and Fall of the Roman Empire. Go to The Tough Guide to the Known Galaxy and read the entry "FALL OF EMPIRE". Examples: the Foundation novels of Isaac Asimov, THE LAST PLANET aka STAR RANGERS by Andre Norton, the Dominic Flandry novels of Poul Anderson, THE COSMIC COMPUTER aka JUNKYARD PLANET by H. Beam Piper, GALACTIC DERELICT by Andre Norton, THE REDISCOVERY OF MAN by Cordwainer Smith, BIRTHRIGHT: THE BOOK OF MAN by Mike Resnick.
"The Long Night." Worlds reverting to pre spaceflight conditions, savagery, barbarism, primitive forms of life, superstition. Worlds taking to barbarian raids on defenseless isolated planets, hastening the downfall of knowledge. Interstellar trade and communication fails. Knowledge and technology is lost. Fragments of spaceflight, fragments of empire, some starships, some efforts to revive. Rise of petty wars and kingdoms. Thousands of years of loss of contact. Humanity in this period becomes indigenous to most of the habitable planets of the galaxy, forgetting origins. Evolutionary changes may take place. Alteration of form to fit differing world conditions — giant men, tiny men, water-dwelling men, flying men, mutations. Rairly this can end with the extinction of humanity. Go to The Tough Guide to the Known Galaxy and read the entry "INTERREGNUM". Examples: EARTHBLOOD by Keith Laumer, SPACE VIKIKG by H. Beam Piper, THE REDISCOVERY OF MAN by Cordwainer Smith, THE ARMAGEDDON INHERITANCE by David Weber, the Interstellar Empire novels of John Brunner.
Rebirth of civilization. Interstellar trade and communications resume, and the seeds of a new Empire are planted. Examples: "Starfog" and "The Star Plunderer" by Poul Anderson.
From here, the history can circle round back to Formation of Empire. Otherwise, it leads up to:
Restoration of commerce between worlds. The reexploration of lost and uncontacted worlds and the bringing them back to high-technology, democratic levels. The efforts to establish trade between human worlds that no longer seem kin. Beating down new efforts to form empires, efforts which sometimes succeed and revert to approximations of the previous period, with similar results. Eventual rise of galactic harmony among intelligences. The exploration of other galaxies and of the entire universe. Examples: THE MOTE IN GOD'S EYE by Niven and Pournelle, "Herbig-Haro" by Harry Turtledove, EMPIRE by H. Beam Piper, WARLORD by S.M. Stirling and David Drake.
Everybody wears togas. Galactic harmony and an undreamed of high level of knowledge leads to experiments in creation, to harmony between galactic clusters, and possible exploration of the other dimensions of existence. The effort to match Creation and to solve the last secrets of the universe. Sometimes seeking out and confronting the Creative Force or First Cause itself, sometimes merging with it. The end of the universe, the end of time, the beginning of a new universe or a new space-time continuum. Humanity ascends to a higher plane of existence or mysteriously vanishes/goes extinct. Examples: LAST AND FIRST MEN and STAR MAKER by Olaf Stapledon, THE CITY AND THE STARS by Arthur C. Clarke.
The following is some suggested reading on the topic of predicting enough broad historical trends that can be used to manufacture your future history. In the following, the term "Psychohistory" refers to the fictional science created by Isaac Asimov in his Foundation trilogy, not the modern Psychohistory. "Cliology" is a variant on Asimovian Psychohistory.
If you are trying to write your own future history, legendary SF author Isaac Asimov shows the way. He took the Decline and Fall of the Roman Empire, filed off the serial numbers, replaced "Roman Empire" with "Galactic Empire", and thus wrote the Foundation Trilogy. (I jest. Asimov did much more than that. Asimov is one of the giants of science fiction and his Foundation trilogy is rightly considered to be one of the best SF series ever written, period. It's the trilogy, the latter books are to be ignored.) Noted SF author Ken MacLeod said "History is the trade secret of science fiction." If you find Gibbon's Decline and Fall a little overwhelming, there is always the Complete Idiot's Guide to the Roman Empire. If you want something in between, try The Grand Strategy of the Roman Empire by Edward Luttwak. For a "crossover" science fictional history, read here. And go to The Tough Guide to the Known Galaxy and read the entry "COSMIC BACKGROUND HISTORY".
You can use other sources than history. Glen Cook's marvelous novel SHADOWLINE is a re-telling of Norse mythology. Only instead of Norse gods, it is about futuristic mercenary companies. The mercenary leader Storm is an Odin figure, sending two telepathic flying lizards around to spy in the same way Odin sent Huginn and Muninn. He has robot drone aircraft flying around various battlefields. If they spot some soldier who is valiant, when the soldier is killed the drones swoop down and carry off the body. The soldier is brought back to life by advanced medical techology and given the opportunity to enlist with Storm's mercenary legion, to fight and be reborn forever. This parallels the Norse tales of Valkyries and the undying warriors of Valhalla.
If you want a slightly more scientific method, you could take a stab at simulating future history.
From Probapossible Prolegomena to Ideareal History by James Blish (1978). Blish expounds upon the historical theories of Oswald Spengler.
For a good overview of the history of the world in 48 pages, try David Maurer's Explanation of history. If you read the section on Aristocrat Tribal Societies, you will find a plausible explanation of the psychology of the Klingon Empire. Maurer covers the economic stages a nation goes through, with each state boiling down to a new answer to the problem of "where is the food going to come from?" Another book about stages is The Grand Strategy of the Roman Empire by Edward Luttwak. And don't miss the Inglehart-Welzel Cultural Map of the World.
When getting down to basics, remember that the word Lord comes from the Old English word hlaford, which was derived from the Old English hlafweard. The word hlaf means "bread" or "loaf" and weard means "keeper" or "guardian", so Lord means "Keeper of the food". You give your allegiance to your lord because he's the one who gives you food. Meanwhile Lady come from the Old English word hlæfdige. -Dige means "maid", and is derived from dæge or "maker of dough."
In other words, the Lord brings home the bacon, and the Lady cooks it. And the Lord's men are loyal because he feeds them.
Without the plow, all one person could manage to feed was themselves and maybe their family. Such cultures had to have 100% employment in the food raising industry. The culture could not afford the luxury of supporting citizens who were inventors. But with the invention of the plow, suddenly a surplus of food appears. Inventors can be supported, and the headlong rush of technological progress is off and running.
And in Jerry Pournelle's Janissaries, the Earth mercenaries are marooned on a primitive planet. The first thing they ask for from their alien owners is a copy of James Burke's Connections book. If you haven't seen Burke's documentary series Connections or The Day The Universe Changed, you might consider renting a copy.
In his epic series Cities In Flight, James Blish based his future history on the theories of Oswald Spengler's book The Decline of the West and its civilization model. Spengler's thesis is that civilizations and cultures go through well defined stages in their life-cycle. This is obviously a big help to the SF author trying to create the history of the future.
In the appendix to the omnibus volume of Cities in Flight, Leland Sapiro has a short essay outlining Spenglerian theory, and includes a chart of the stages of the life-cycle of a civilization (it also mentions how incredibly difficult it is to make a chart like this). It illustrates the stages with example from the cultures of ancient Greece, Arabia, Western, and Blish's "Earthmanist". (the latter stages of Western culture are also fictional ones from Blish, since Western culture hasn't collapsed yet. Or at least not that I've noticed.) Fictional entries are in brown text.
|Period||The Classical Culture||The Arabian Culture||The Western Culture||The Earthmanist Culture|
Tribes and their chiefs; no politics, no State. Chaos of primitive expression forms.
Mycenean Age, "Agamemnon"
Frankish Period, Charlemagne
Vegan-War Period Admiral Hrunta
|Culture. Early Period.||1100-650||0-500||900-1500||2464-3111|
|P1. Formation of Feudal Order||1100-750||0-400||900-1254||2464-3089|
|R1. Spiritual Spring: the Priestly Myth||Demeter cult||Primitive Christianity||German Catholicism||Hruntanism|
|R1. Spiritual Spring: the Military Myth||Trojan War||Gospels, Apocalypses||Siegfried, Arthur||Vegan-War Myth|
|A1. Early forms, rural, unconsciously shaped||Doric||The cupola||Gothic||-|
|R2. Mystical-metaphysical shaping of Myth||Cosmogonies||Patristic literature||Scholasticism||-|
|P2. Breakdown of Feudal Order: The Interregnum||750-650||400-500||1254-1500||3089-3111|
|R3. Spiritual Summer: the Reformation||Orphism, et al.||Monophysitism, et al.||Huss- Luther- Loyola||Arpad Hrunta|
|A2. Exhaustion of possibilities in Early forms||Late Doric||Proto-Arabesque||Early Renaissance||-|
|Culture. Late Period.||630-300||500-800||1500-1815||3111-3925|
|P3. Formation of a World of Aristocratic States||650-487||500-661||1500-1660||3111-3602|
|R4. First purely philosophical world views||Pre-Socratics||In Jewish literature||Galileo, Bacon||-|
|M1. Formation of a new Mathematic||Geometry||Algebra||Analysis||Matrix mathematics|
|A3. Mature art forms, urban and conscious||Ionic||Zenith of mosaic art||Baroque||-|
|R5. Puritanism; opposition to rising absolutism||Pythagoras||Mohammed||Cromwell; the Fronde||The Duchy of Gort|
|P4. Climax of the State-Form ("Absolutism"):|
Aristocracy held in check by alliance of King (or Tyrant) with Bourgeoisie
Age of Themistocles and Pericles
The Omayyad Caliphate
The Ancient Regime
Earth and Okies vs. Colonials
|R6. Spiritual Autumn: the Enlightenment||Socrates||The Mutazilites||Locke, Rousseau||-|
|A4. Intellectualization of Mature art forms||Myron, Phidias||Arabesque||Rococo||-|
|M2. Zenith of mathematical thought||Conic sections||Spherical trigonometry||The infinitesimal||-|
|R7. The Great Conclusive System: Mystic||Plato||Alfarabi||Goethe, Hegel||-|
|R7. The Great Conclusive System: Scholastic||Aristotle||Avicenna||Kant||-|
|P5. Revolution and Napoleonism|
Bourgeoisie against alliance of King (or Tyrant) and Aristocracy; victory of Money over Blood.
Partisans of Philip; Alexander
The Kufans; the first Abbassids.
Okies vs. Earth and Colonials.
|A5. Exhaustion and dissolution of Mature forms||Corinthian||"Moorish" art||Romanticism||-|
|Civilization and Spiritual Winter||300-0-300||800-1400||1815-2522||3976-4104|
|P6. Transition from Napoleonism to Caesarism|
The Period of Contending States; dominance of Money ("Democracy").
From Alexanderism to Caesarism.
From Caliphate to Sultanate.
From Napoleonism to
|In Cloud 3998-4104|
New York vs. IMT; Jorn vs. New York
|R8. Materialism (science, utility, prosperity)||The Cynics||Brethren of Sincerity||Comte, Darwin, Marx||The Stochastics|
|R9. Ethical-social ideals replacing religion||Epicurus, Zeno||Movements in Islam||Schopenhauer, et al.||-|
|M3. Mathematics: the concluding thought||Archimedes||Al-Biruni||Riemann||-|
|R10. Spread of final world sentiment||Roman Stoicism||Practical Fatalism||Ethical Socialism||-|
|A6. Art problems; craft art||Hellenistic art||Spanish-Sicilian art||Modern art||-|
Victory of force-politics over Money; decay of the nations into a formless population, soon made into an imperium of gradually increasing crudity of despotism.
Sulla, Caesar Tiberius, up to Domitian.
The Seljuk Sultanate.
MacHinery and Erdsenov; rise to full power of Bureaucratic State.
The Triumph of Time Over Space
|A7. Artificial, archaic, exotic art forms.||Roman art||"Oriental" art||-|
|Rll. Second Religiousness (in the masses only)||Syncretism||Syncretic Islam||Adventism; Witnesses|
|P8. THE FINAL POLITICAL FORM|
The world as spoil. Gradual enfeeblement of imperial machinery against raiders and conquerors. Primitive human conditions thrusting up into the highly civilized mode of living.
Full power of the Empire, then disintegration in the West.
Rise-fall of the Ilkhanate; rise of Ottoman Turks under whom the moribund culture endures to 1920.
Full power; then decline and fall of Bureaucratic State.
|A8. Fixed forms, giganticism, imperial display||Triumphal arch||Gigantic buildings||The Jupiter Bridge|
|The Aftermath||After 284|
Arabinization in the East.
Westernization of the Arabian lands and entire world.
Galaxy proper conquered by Web of Hercules.
Leland Sapiro's chart was used in the classic computer game Omnitrend's Universe. ( here, here, here, here, here, here ). It was used to classify the cultural level of each planet. It determined the types of products that were illegal to import.
Omnitrend's Universe. Appendix G: Cultural List
A Guide To Cultural Epochs
Since the latter part of the Nineteenth Century [Common Era], historians have been dividing cultures into "epochs." Epochs are the turning points in the history of a culture. For example, the rise of George Louis I was a new epoch in New Europe culture.
All the cultures in the Local Group have undergone a careful examination and classification by the Janet Leader Foundation on Arbest. These classification codes help the traveler to determine what the import and immigration restrictions are.
Code Epoch Description Accept Immigrants Illegal Product Types 1 Pre-Cultural Clans, tribes, no politics. A chaos of primitive expression. Yes [none] 2 Fuedalism Rural art, naturally shaped. Warriors and Priests in power. No ARTI, EDUC, INFO 3 Breakdown of Fuedalism Exhaustion of early art forms, the Reformation. Yes ARTI, NARC, ENTR, PERS, JEWL 4 Formation of Aristocratic States Mature art, new forms of math, philosophical world views and puritanical religions opposed to growing absolutism. No ARTI, EDUC, NARC, PERS, JEWL, FURN, CLTH, FOOD 5 Absolutism Aristocracy held in check by King/Tyrant with Bourgeoise. The zenith of mathematical thought, intellectualization of art, the great conclusive systems of thought. Yes WEAP 6 Revolution and Napoleonism Bourgoise against alliance of King/Tyrant and Aristocracy. The Victory of Money over Blood. Exhaustion of art forms. No EDUC, TRANS, INFO, WEAP 7 Transition from Napoleonism to Caesarism The epoch of Contending States. Dominance of Money ("Democracy"). Rational social ethics replace Religion. Final world sentiment. Conceptual art. Final Thought in Mathematics. Yes NARC, SLAV, BOGU 8 Caesarism Victory of Force-Politics over Money. The decay of nations into a formless mass, soon to be made into an imperium of gradually increasing despotism. Archaic, exotic art. No EDUC, WEAP, BOGU 9 Final Political Form The world as a spoil. Primitive human conditions thrusting up into the highly civilized mode of living. No [none]
ARTI - artifact; BOGU - bogus items; CLTH - clothing; EDUC - educational materials; ENTR - entertainment; FOOD - food; FURN - furniture; INFO - information; JEWL - jewelry; NARC - narcotics; PERS - personal items; SLAV - slaves; TRANS - transportation; WEAP - weapon
Novel that have a background of cyclical history include The Last Planet AKA Star Rangers by Andre Norton, the Cities in Flight novels of James Blish, Birthright: The Book of Man by Mike Resnick, Macroscope by Piers Anthony, the Childe Cycle novels of Gordon Dickson, the Mote in God's Eye by Larry Niven and Jerry Pournelle, the LaNague Federation novels of F. Paul Wilson, the Polesotechnic novels by Poul Anderson, and of course the Foundation trilogy (with the prequels The Stars Like Dust, The Currents of Space, and Pebble in the Sky) by Isaac Asimov. The old bromide is that history never repeats itself, but sometimes it rhymes.
In the short story "The Only Thing We Learn", by Cyril M. Kornbluth (1949), the frontier rebels are attacking Earth and the Home Stars, and they are doing a good job of it. Earth wing commander Arris and historian Glen wait for the frontier rebels to come and finish them off.
In this novel, the humans of Terra develop a faster-than-light starship, only to discover that Sol is inside an alien interstellar federation several thousand years old: Central Control. C.C. only allows Terrans into the rest of the galaxy as third-class citizens, barely tolerated and only allowed off-world in the narrowly role defined by C.C.: that of mercenary.
It is instructive to compare the bold-face text in the quote below with the bold-face text in the "The Only Thing We Learn" quote above.
A common failing of with those who write future histories is a failure to take into account Future Shock, that is, the rapid progress of technological advancement. Refer to the "Apes or Angels" argument. Consider that one hundred years ago the paper clip had just been invented, Marconi had invented the wireless radio, the Wright brothers had invented the airplane, and the latest cutting edge material was Bakelite. Assuming that technology continues to advance at the same rate, all of our flashy technological marvels of today will look just as quaint and obsolete in the year 2100. And in 2500, they will look like something made by Galileo.
Remember, this assumes that the rate of technological progress remains the same. The evidence suggests that the rate is increasing.
When it comes to futures histories in various SF novels, the main failing I have noted is a failure of scope. While you may read novels with orbital beanstalks, immortality drugs, virtual people living in digital cyber-reality, nanotechnology, transhumanity and post-humans, Dyson spheres, teleportation, zero-point energy, matter duplicators, time travel, cloning, and cyborgs; you almost never find an individual novel that has all of these things (although Greg Egan's DIASPORA comes close, and the Orion's Arm project comes even closer).
This is because future history SF novels are not meant to predict the future, so much as they are meant to illuminate a specific point the author is trying to make.
Around 1910, the hot multiple-use buzzword was "Electric," as in Tom Swift and His Electric Runabout or Tom Swift and His Electric Rifle. In the 1920's it was "Radio." Radio was just coming into regular use, so it was new and exciting. In the 1940's it was "Atomic," for obvious reasons. In the 1950's it was "Transistorized". In the 1960's it was "Laser". In the 1970's it was "Computerized". Currently it is "Nanotechnolgy."
If all you have is a hammer, everything looks like a nail. Even if it actually a screw. So if you invent some fabulous scientific breakthrough for your SF story, try to resist the temptation to use it as the solution for everything. You can see how silly it becomes.
Naturally, the more specific the details of your future technology that you describe in your SF story, the bigger the risk that it is going to sound quite silly in the decades to come. This is called "Zeerust", and of course TV Tropes has a page devoted to it just chock full of entertaining examples and associated tropes (food pills, jet pack, video phone, flying car, etc).
My favorite example is "Into the Meteorite Orbit" by Frank K. Kelly (1933).
It starts out so good. It predicts air-traffic controllers, the 22nd century as being dominated by the energy crisis, it even has the hero finding a recorded message on his video-telephone.
Then the reader's willing suspension of disbelief crashes and burns as the hero pulls the wax cylinder out of the video-telephone, puts it in the replay unit, and places the needle on the groove. Oops.
And then there were the slide-rules in a short story by A. E. Van Vogt, complete with a radio link to the ship's computer.
In "How to Build a Future", John Barnes suggests as a rule of thumb one shouldn't try predicting technological advances past 500 years or so. He got this by assuming that each epoch of advance is composed of 90% of existing technology miniaturized, turbo-charged, or otherwise improved and 10% technology that is "magic" (in the sense of Clarke's Third Law) coming from scientific breakthroughs. An example of the 90% would be the development of the propeller airplane into the jet airplane, an example of the 10% would be the invention of the laser. His thinking is that while one can extrapolate improvements in existing technology, breakthroughs cannot be visualized. Indeed they would be almost incomprehensible (imagine trying to explain the quantum mechanical basis of the transistor to Thomas Edison). The first epoch would be 10% magic. The second would be an extension of the first plus 10% new magic, for a grand total of 19% magic. By epoch 7 it will be 52% magic. After about 500 years of technological epochs, the current technology approaches 100% magic as compared to the starting technology, hence the 500 year rule of thumb. Keep it up and you'll have a Vingian Singularity.
Authors who worry about such details try to come up with a way to put the brakes to progress. Barnes postulated a "inward turn" in his A MILLION OPEN DOORS. In his DUNE novels, Frank Herbert has the "Butlerian Jihad". In Jerry Pournelle's CoDominion novels, the government suppresses all research that might upset the military balance, which is basically all research. In Andre Norton's THE STARS ARE OURS, Terra is controlled by a fundamentalist Luddite regime which swept into power after a close brush with nuclear Armageddon.
Funny thing about society in general and people in specific. Back in the 1750's this new thing called "Science" really started coming into its own. It was amazing the things it could discover, and so many of them with marvelously practical uses! It seemed like there was nothing science could not do. Science was going to bring us to a grand and glorious utopian future. Even now there is some nostaligia for this view, the technical term is "Retro-Futurism".
This all turned to worms in the early 1900's. Suddenly science revealed its dark side. Science unleashed unspeakable horrors, there were things man was not meant to know, and one started to see more and more dystopias in science fiction literature.
Science didn't change, it can't. The change was in the attitude of society.
So what happened? Yes, I know most of you suddenly shouted "The invention of the atom bomb, you moron!". BZZZT! You're wrong, thank you for playing. It was already in full swing long before 1945. So what's the answer?
I believe that master science fiction author and science explainer Isaac Asimov has the answer. He wrote about it in a 1969 essay entitled The Sin of the Scientist (collected in The Stars In Their Courses). He was speculating on what a "scientific sin" would be. Turns out it would be an act that would blacken the very name of science itself.
Some space opera writers are fascinated with the romantic concept of star conquerors charging out of their interstellar star ships on horseback, waving longswords. While cinematically interesting, the concept is obviously scientifically silly, surely somebody advanced enough to run an FTL starship can manage to cobble together a laser pistol (or a submachine gun). A related notion is a high-tech interstellar empire threatened by "barbarians" waiting in their FTL longboats at the rim of the empire. One wonders about the tech assumptions though. Either starships are relatively cheap (ponder the idea of "barbarians" fielding aircraft carriers as a comparison) or the smallest feudal units are pretty good sized.
A common fig-leaf is updating the sword into a laser-sword, and inventing some imaginative reason why using said sword on a group of pistol-packing thugs is not tantamount to bringing a knife to a gunfight (Use the Force, Luke!). Another fig-leaf is allowing laser pistols, but with such lousy power supplies that there is a ten-minute recharge delay between each shot, along with some dubious reason to prevent the use of gunpowder weapons but allow swords.
In his DUNE novels, Frank Herbert makes a frantic hand-wave with his Holtzman effect personal force fields, which miraculously render laser pistols and conventional handguns worthless, forcing people in the far future to rely upon swords. Along with his Butlerian Jihad, it makes the universe of ten thousand years from now look remarkably medieval.
Poul Anderson had this comment on de Camp's analysis:
This may or may not be the story John Brunner was referring to:
In The Warlock of Rhada by Robert Cham Gilman, one thousand years after the fall of the first galactic empire, warriors are armed with swords and ride horses, but by golly the starships still work. Built to last.
Joan Vinge pointed out an unexpected consequence of the collapse of technology in her THE OUTCASTS OF HEAVEN'S BELT. If a planetary colony falls into barbarism, everybody reverts to a non-technological agrarian society. If an asteroid civilization falls into barbarism, everybody dies. It takes lots of technology to run the oxygen system, airlocks, spaceships, hydroponics, nuclear reactors, and other items vital for life in space. No technology, no life. In other words, they are a Hydraulic state.