Tech Levels

Tech Level

Variations Within a Tech Level

The equipment listed for a TL does not appear all at once as soon as a society enters that TL. Instead, items appear gradually after that date.

Shortly after a TL begins, devices from the previous TL will be common – along with experts in skills associated with those items. A player could easily justify a PC with a personal TL one step below that of his society, or with one or two skills that are several TLs out of date. As the TL wears on, devices from the next TL start to appear. If PCs wish to obtain such equipment, they must either invent it or buy a prototype – see New Inventions. Access to prototypes is not sufficient to justify a PC with a personal TL above that of his society! At the GM's option, adventurers may have a skill penalty of -1 or more when dealing with technology of their own TL that is more or less advanced than what they are used to. Treat this as an unfamiliarity penalty; see Familiarity.

Finally, the GM should be aware that not every item of a given TL must appear in every society that attains that TL. The GM always has the final say as to which items are currently available – both to the PCs and in the game world in general.

"Tech level" (TL) is a general rating of a society’s highest achievement in technology (or a certain type of technology). Tech levels run from zero on up. Each TL describes a set of technologies that become available after a certain point in time. The standard TLs, and associated eras on Earth, are:

TL0 – Stone Age (Prehistory and later). Counting; oral tradition.
TL1 – Bronze Age (3500 B.C.+). Arithmetic; writing.
TL2 – Iron Age (1200 B.C.+). Geometry; scrolls.
TL3 – Medieval (600 A.D.+). Algebra; books.
TL4 – Age of Sail (1450+). Calculus; movable type.
TL5 – Industrial Revolution (1730+). Mechanical calculators; telegraph.
TL6 – Mechanized Age (1880+). Electrical calculators; telephone and radio.
TL7 – Nuclear Age (1940+). Mainframe computers; television.
TL8 – Digital Age (1980+). Personal computers; global networks.
TL9 – Microtech Age (2025+?). Artificial intelligence; real-time virtuality.
TL10 – Robotic Age (2070+?). Nanotechnology or other advances start to blur distinctions between technologies ...
TL11 – Age of Exotic Matter.
TL12 – Whatever the GM likes!

Note that TLs have start dates but not end dates. The innovations of a given TL fade as those of higher TLs displace them, but they rarely vanish completely. A blacksmith in 1850s England uses TL3 techniques to shoe the horses that pull the carriage the gentleman rides to catch his TL5 train to London – and those techniques might still exist in TL8, albeit as a quaint hobby. The GM should decide which "dated" technologies remain in use in his game world, and which items from earlier TLs are still commonly available for purchase.

Differences in tech level become very important when adventurers travel between societies. Technology is likely to seem like magic to anyone more than three or four TLs less advanced. If a WWII soldier (TL6) gets dropped back into the days of King Arthur (TL3) ... things get interesting. Of course, time travel isn’t necessary – even today, you can drop back three or four TLs if you visit the right part of the world.

A party always attracts attention if it displays technology from a higher TL than that of the locals. This attention might take the form of worship, awe, curiosity, envy, fear, or hatred – the greater the disparity in TL, the stronger the reaction.

The GM should set a "baseline TL," which describes most societies in the game world, most of the time. However, exceptions may exist.

Backward Societies

A society might have a lower TL across the board. This could be because it is impoverished, isolated (either geographically or economically), resistant to change (such as 17th-century China), or regressed (possibly in the wake of war or natural disaster). PCs from such societies will have the Low TL disadvantage.

Advanced Societies

Likewise, the TL of a particular society might be higher than that of the rest of the game world. If the GM chooses to introduce such advanced societies, he should ensure that PCs who wish to use their advanced technology pay the points and cash to acquire it honestly. PCs from such societies must have the High TL advantage.

Split Tech Level

Realistic societies rarely have the same TL in every field of endeavor; they tend to be advanced in some fields, backward in others. GMs who desire extra detail can rate each society for its TL in a few key areas. It is most efficient to list only those TLs that differ from the baseline; e.g., "TL8 (Communications TL7, Medical TL9)."

PCs have a personal TL equal to their society's baseline TL, but the TL of their technological skills matches that of their society in the relevant area.

Borrowed Technology

A society can be familiar with technology that it does not itself possess. This is frequently the case for low-tech societies with high-tech neighbors, and for colonies. A village with Iron Age technology (TL2) might be quite familiar with the TL3 steel weapons carried by travelers, and richer villagers might have a few, but local smiths could not duplicate or repair them. Express this as "TL2/3." PCs from such societies have a personal TL equal to the lower TL, but may learn the skills needed to use (but not repair or design) equipment of the higher TL.

Building Up Local Technology

There may be times when you need to improve the local TL. A group of castaways might have high-tech knowledge, but little or no equipment to work with. In that case, they need to "build the tools to build the tools" to use their technological knowledge. In extreme cases, your castaways might have to go all the way back to primitive mining to get the ore to refine to metal to build the tools to build the tools...! Or a single traveler might want to impart his high-tech knowledge to the people he is visiting. (We assume that he has the cooperation of his hosts, or he doesn't have a chance.)

Any such situation is largely at the GM's discretion. But it can be done. Some of the best adventure stories of all time have revolved around one of these premises: Swiss Family Robinson, Lord Kalvan of Otherwhen, the Riverworld series, A Connecticut Yankee in King Arthur's Court, etc.

General guideline: a "science" is one of the categories of knowledge listed under Tech Level by Field. It takes two years of work to move each science from one TL to the next, assuming that:

(a) you have an ample supply of labor;

(b) you have an ample supply of raw materials;

(c) you are fully familiar with the lower TL (all relevant skills at 12+); and

(d) you know where you're going, and are fully familiar with the higher TL (all relevant skills at 12+).

This rule is specifically for high-TL characters re-inventing or introducing technology to a low-tech society or situation. It does not cover inventions – for that, see New Inventions.

Different Technolgies

Some technologies (and some societies) do not fit nicely onto the standard tech-level charts. GMs who run into this problem might wish to use one of the optional rules below.

Improving Skills in Alternate Tech Levels

An adventurer who wishes to learn a technological skill can save points if he already knows that skill at another tech level. Treat the skill at the new TL as a different skill that defaults to the known skill at the penalty listed under Tech-Level Modifiers; e.g., Engineer/TL5 defaults to Engineer/TL7 at -3. Handle improving skills from "cross-TL" defaults identically to improving any skill from default; see Improving Skills from Default. (If your skill is not high enough to let you start from a favorable default, ignore these rules and learn the skill normally.)

Technology Paths

Certain categories of inventions might appear in an order other than that suggested by the default TLs. In particular, there is no guarantee that TL9+ technologies will appear in the order GURPS predicts. Apply the Split Tech Level rule as liberally as you wish to simulate your favorite genre! For instance, in a "cyberpunk" society, computing, bionics, and biotechnology might be two to four TLs more advanced. In contrast, a "retro-tech" setting that mimics 1940s sci-fi might have computers frozen at TL6 but many other technologies at anywhere from TL9 to TL12. Any combination is possible!

Divergent Tech Levels

In other cases, a society has a single, consistent TL – but it got there along an unusual path. The GM can designate this "divergent TL" with the notation "TL(x+y)," where x is the TL at which the technology diverged, y is the number of TLs since the divergence, and the sum x+y is the effective TL for most purposes.

Example: TL(5+1) is effectively TL6 – but a different TL6 that split off at TL5. TL(5+1) devices produce similar results to TL6 ones, but look little like those devices and rely on different operating principles. A TL(5+1) "steampunk" world based on Victorian visions of the future might have steam cars, steam dirigibles, and high-speed telegraph lines instead of the automobiles, airplanes, and telephones of TL6.

Divergent TLs are not unique. There could be any number of versions of (for instance) TL(5+1), each different in its own way. The GM should specify what caused the split in each case, be it different thinking, different prevailing physics, or something else.

Characters used to a "normal" or "differently diverging" TL suffer an additional -2 penalty for unfamiliarity, over and above any penalties for TL differences, when dealing with divergent technology.

Superscience

(List of Superscience Articles)

"Superscience" technologies violate physical laws – relativity, conservation of energy, etc. – as we currently understand them. Examples of superscience technologies appear under Tech Level by Field, and several articles of superscience equipment appear in Chapter 8.

By definition, it is impossible to set a firm TL for superscience – we might discover faster-than-light travel tomorrow, a thousand years from now, or never. Equipment TLs are always debatable, but superscience

TLs are arbitrary. To reflect this, the rules give the TL of superscience developments as "^" instead of a number. The GM is free to assign such innovations to any TL. To note a superscience invention that appears at a specific TL in a particular game world, put a “^” after its TL; e.g., "TL3^" for a TL3 superscience item.

Remember: superscience doesn't have to change a society's overall TL, create a new technology path, or cause a divergent TL. It just adds totally new developments to all the usual technologies for a given TL in that society.

Tech Level and Starting Wealth

Tech level determines starting wealth, as technologically advanced societies tend to be richer. Below is a comparison of TLs and suggested starting wealth.

TL	Example	Starting Wealth	Typical Monthly Pay
TL0	Stone Age (Prehistory and later)	$250	$625
TL1	Bronze Age (3500 B.C.+)	$500	$650
TL2	Iron Age (1200 B.C.+)	$750	$675
TL3	Medieval (600 A.D.+)	$1,000	$700
TL4	Age of Sail (1450+)	$2,000	$800
TL5	Industrial Revolution (1730+)	$5,000	$1,100
TL6	Mechanized Age (1880+)	$10,000	$1,600
TL7	Nuclear Age (1940+)	$15,000	$2,100
TL8	Digital Age (1980+)	$20,000	$2,600
TL9	Microtech Age (2025+?)	$30,000	$3,600
TL10	Robotic Age (2070+?)	$50,000	$5,600
TL11	Age of Exotic Matter	$75,000	$8,100
TL12+	Whatever the GM likes!	$100,000	$10,600

GURPS gives wealth and prices in "$" for convenience. The $ can stand for "dollars," "credits," "pennies," or even units of barter. In a contemporary setting, $1 is a modern U.S. dollar. In other periods, $1 equates roughly with the amount of local currency needed to buy a loaf of bread or equivalent staple – not with historical U.S. dollars.

For example, in a high medieval society, each $ might be a copper farthing. In WWII-era America, each $ would convert to $0.10 in deflated 1940s-era dollars. And in a cyberpunk world with hyperinflation, each $ might equal $1,000 in grossly devalued 2030-era dollars! The GURPS $ is a constant, however. Variations in starting wealth by TL reflect increased prosperity due to civilization’s progress – not inflation.

Worldbooks might give starting wealth, wages, and prices in local currency – historical U.S. dollars, British pounds, pieces of eight, etc. In such cases, they will always give a conversion factor to constant $.

Tech Level and Equipment

You enter play with "starting wealth" appropriate to the campaign TL. If you are from a higher TL, you may start with access to the equipment of your personal TL. However, the price of an item of equipment is doubled for every TL by which its TL exceeds that of the campaign!

For instance, a TL8 character in a TL3 game world starts with the same $1,000 as everyone else at TL3. If he wants a TL8 assault rifle that normally costs $1,500, it costs him 32 times as much (five TLs of difference results in five doublings, or a factor of 32) – or $48,000 – since the rifle is far more valuable in a low-tech setting. He'd need to start with some Wealth!

There is no guarantee that high-TL adventurers will continue to have access to high-tech gear in play. If you want a piece of gear, then you should buy it when you start out. If your TL8 adventurer is dropped into a TL3 world with 100 rounds of ammunition for his assault rifle, then he had better use it wisely. Once it's gone, it's gone...

Tech Level and Genre

When designing a game world with a specific genre in mind, the GM should be sure to choose a TL that will meet his players' expectations for the genre. Some examples:

• Sword & Sandal: Gladiators, chariots, and amazons. TL1-2.
• Medieval Fantasy: Knights, wizards, and castles. TL3.
• Warring Provinces Japan: Samurai and ninja. TL3-4.
• Swashbucklers: Pirates and musketeers. TL4.
• Wild West: Cowboys and Indians. TL5.
• Steampunk: Fiction of Jules Verne and H.G. Wells. TL5, diverging to TL(5+1).
• Pulp: Archaeologists and detectives between the World Wars. TL6.
• WWII: Axis and Allies. TL6.
• Cold War: Capitalism vs. communism. TL7.
• Modern Day: You're living in it! TL8.
• Cyberpunk: Netrunners and cyborgs. TL9.
• Space Opera: Interstellar adventure. TL10+, plus superscience.

Tech Level by Field

It is often important to know what a given TL implies for a particular area of knowledge – for instance, when using the Building Up Local Technology and Split Tech Level rules. The tables below outline the effects of TL on four sample fields. Many other such fields exist: architecture, communications, materials, etc.

Transportation

TL0 – Skis; dogsleds; dugout canoes.
TL1 – Bare horseback; the wheel (and chariots); shipbuilding; sails.
TL2 – Saddle; roads; triremes.
TL3 – Stirrups; oceangoing sailing ships (longships, roundships, etc.).
TL4 – Stagecoach; three-masted sailing ships; precise navigation.
TL5 – Steam locomotives; steamboats; early submersibles; balloons and early airships.
TL6 – Automobiles; continental railways; ocean liners; submarines; aircraft.
TL7 – Nuclear submarines; jet aircraft; helicopters; manned space flight.
TL8 – Satellite navigation; SSTO ("single stage to orbit") spacecraft.
TL9 – Robot cars; space elevators; manned interplanetary space flight.
TL10 – Fast interplanetary space flight.
TL11 – Manned interstellar space flight.
TL12 – Fast interstellar space flight.

Superscience! Reactionless thrust; contragravity; faster-than light (FTL) travel; matter transmission; parachronic technology; time machines.

Weapons and Armor

TL0 – Wooden and stone weapons; primitive shields; hides for armor.
TL1 – Bronze weapons and armor.
TL2 – Iron weapons; iron armor (including mail); siege engines.
TL3 – Steel weapons; early firearms; plate armor; castles.
TL4 – Muskets and pikes; horse artillery; naval broadsides.
TL5 – Early repeating small arms; rifled cannon; ironclads.
TL6 – Smokeless powder; automatic weapons; tanks; combat aircraft.
TL7 – Ballistic body armor; guided munitions; combat jets; nuclear weapons.
TL8 – Smartguns; blinding lasers; unmanned combat vehicles.
TL9 – Electrolasers; heavy laser weapons; battlesuits; combat robots; designer viruses.
TL10 – Compact laser and heavy particle-beam weapons; Gauss guns; nanotech armor; nanoviruses; antimatter bombs.
TL11 – Compact particle-beam weapons; disassemblers ("gray goo"); defensive nanites.
TL12 – Gamma-ray lasers; “living metal” armor; blackhole bombs.

Superscience! Monomolecular blades; force-field technology; gravitic weapons; nuclear dampers; disintegrators.

Power

TL0 – Human muscle power; dogs.
TL1 – Donkeys; oxen; ponies.
TL2 – Horses; water wheels.
TL3 – Heavy horses and horse-collars; windmills.
TL4 – Improved windmills; belt drives; clockwork.
TL5 – Steam engines; direct current; batteries.
TL6 – Steam turbines; internal combustion; alternating current; hydroelectricity.
TL7 – Gas turbines; fission; solar power.
TL8 – Fuel cells; advanced batteries.
TL9 – Micro fuel cells; deuterium-hydrogen fusion; high-temperature superconductors.
TL10 – Helium-3 fusion; antimatter.
TL11 – Portable fusion power.
TL12 – Portable antimatter power.

Superscience! Broadcast power; cold fusion; zero-point energy; total conversion; cosmic power.

Biotechnology/Medicine

TL0 – First aid; herbal remedies; primitive agriculture.
TL1 – Surgery; animal husbandry; fermentation.
TL2 – Bleeding the sick; chemical remedies.
TL3 – Crude prosthetics; anatomical science.
TL4 – Optical microscope makes cells visible.
TL5 – Germ theory of disease; safe anesthetics; vaccines.
TL6 – Antibiotics; blood typing and safe transfusions; heredity; biochemistry.
TL7 – Discovery of DNA; organ transplants; pacemaker.
TL8 – Genetically modified organisms; gene therapy; cloning.
TL9 – Human genetic engineering; tissue engineering; artificial wombs; cybernetic implants.
TL10 – Brain transplants; uploading; bioroids; uplifted animals.
TL11 – Living machines; cellular rejuvenation.
TL12 – Full metamorphosis; regeneration.

Superscience! Fast-growth clone tanks; psi drugs; regeneration ray.

Ages of Technology

Tech levels can be defined in several ways. Most have a signature technology – e.g., stone, bronze, or iron – alongside other characteristic technologies. These capabilities allow new forms of political and economic organization. Crucial to adventurers, each TL also has a distinctive approach to weapons and warfare.

TL0: The Stone Age

The Stone Age was longer than all of human history. Treating it as one TL is in a way misleading; it encompasses several eras whose technologies differed at least as much as those of ancient Rome and the Middle Ages. In terms important to adventurers, though, it's all fairly similar: small-scale societies that don't support professional warriors or soldiers, armed with stone or wooden hunting weapons. The overall signature technology is worked stone tools and weapons.

Paleolithic (2,400,000 B.C.+)

Signature Technology: Chipped stone.
Other Technologies: Wood, bone, and leather; domesticated dogs; rafts, canoes, and sleds; string; fire; herbs and crude surgery.
Social Organization: Nomadic bands and tribes; rules for marriage, inheritance, and kinship; oral traditions; shamanism.
War: Tribal war bands with hunting weapons; shields.

Mesolithic (8500 B.C.+)

Signature Technology: Multiple small stone chips mounted on a frame or handle.
Other Technologies: Fishing; food storage; basketry; houses.
Social Organization: Chiefdoms and gift-exchange systems; settled communities.
War: Slings; bows and arrows.

Neolithic (8000 B.C.+)

Signature Technology: Ground stone.
Other Technologies: Gardening; food-animal domestication; ceramics; weaving; nets.
Social Organization: Barter; local shrines, priests, and cults.
War: Ditches and other improvised defenses.

Chalcolithic (4500 B.C.+)

At the very end of the Stone Age, native copper comes into use. Some archaeologists call this the Chalcolithic Age. Its technology is essentially that of the Neolithic, with one exception:

Signature Technology: Native copper tools.

TL1: The Bronze Age (3,500 B.C.+)

Signature Technology: Bronze.
Other Technologies: Large-scale agriculture, often with irrigation and plowing; herding; draft animals; wheeled vehicles; large-scale architecture; shipbuilding; written records; practical mathematics; calendars.
Social Organization: City-states and monoethnic empires; written law; armies; long-distance trade and diplomacy; gold and silver currency by weight; marketplaces.
War: Horse-drawn chariots; helmets and body armor; walled cities and siege warfare.

TL2: The Iron Age (1200 B.C.+)

Signature Technology: Iron.
Other Technologies: Riding horses and mounted herdsmen; concrete; large glass objects; arches, vaults, and domes; early water mills; theoretical mathematics; humoral medicine.
Social Organization: Multiethnic empires; founding of universal religions; philosophy; historical scholarship; coinage.
War: Cavalry; war elephants; phalanx warfare; mechanical artillery; specialized war galleys.

TL3: The Middle Ages (600 A.D.+)

Signature Technology: Steel.
Other Technologies: Three-field rotation; mold-board plow; heavy horses; flying buttress; windmills and widely used water mills; distillation; compasses; numerals with zero.
Social Organization: Universal religions; monasticism.
War: Mounted knights; castles; counterweight mechanical artillery; early black-powder weapons.

TL4: The Age of Sail (1450 A.D.+)

Signature Technology: Full-rigged ships.
Other Technologies: Cast iron; the printing press; telescopes; celestial navigation; early synthetic medications.
Social Organization: Nation-states and absolute monarchy; overseas empires; widespread literacy.
War: Cannon; musket and pike; early bayonets; formal military drill; sailing warships armed with cannon; star forts replace castles.

Dirty Tech

High technology isn't always manufactured from carbon fiber, packed with microchips, or glistening with chrome and style. Sometimes, a hero is desperate enough to try almost anything. What would MacGyver or the Professor do in a pinch? Can you fashion a battery on a deserted tropical island, or cobble together functional armor from the contents of the high school cafeteria? Maybe you can! This is "dirty tech."

Throughout High-Tech book are Dirty Tech boxes that contain hasty solutions for hard-up heroes: homemade explosives, field-expedient firearms, jury-rigged electronics, etc. Been aching to use that skill languishing on your character sheet? Wondering why you bothered with that point in Armoury, Chemistry, Electronics Repair, or Machinist? Check out the Dirty Tech entries!

TL5: The Industrial Revolution

The Industrial Revolution (on historical Earth, roughly 1730 to 1880) coincides with the first successful steam engine. It becomes self-perpetuating by embracing curiosity-driven innovation and capitalist economics simultaneously, rewarding risk-taking and invention with wealth. Key developments include:

• Agriculture: Four-course crop rotation, seed drill.
• Arms and Armor: Barbed wire, breech-loading artillery, breech-loading rifle, ironclad warship, mechanical machine gun, nitroglycerine, revolver, rocket.
• Information Technology: Newspaper advertising, photography, public library, scientific journals, telegraph.
• Machinery: Cotton gin, interchangeable parts, powered loom, reaping machine.
• Material Science: Crucible steel, friction match, rubber.
• Medicine and Health: Anesthetic, antiseptic, canned foods, evaporated milk, hypodermic syringe, pasteurization, vaccination.
• Power: Battery, coal, steam engine.
• Transportation: Bicycle, hot-air balloon, macadam road, railroad, screw propeller, steamship, submarine.

TL6: The Mechanized Age

The Mechanized Age (historically, about 1880 to 1940) is the consequence of industrialization sinking its teeth into technologies that are more capital-intensive than labor-intensive and reaping great benefits from the resulting economies of scale. Goods of all types drop in price relative to wages as "modern" transportation and manufacturing techniques hit their stride. Important advances include:

• Agriculture: Herbicides, mechanized harvester, pesticides.
• Arms and Armor: Aircraft carrier, automatic weapons, battleship, high explosives, military aircraft, poison gas, tank.
• Information Technology: Color photography, fingerprint records, motion pictures, radio, sound recording, telephone.
• Machinery: Electric light, radar, sonar, vacuum tube.
• Material Science: Aluminum, Bakelite, Bessemer steel, synthetic fibers.
• Medicine and Health: Blood transfusion, electrocardiograph, inoculation, insulin, penicillin, refrigeration, sterilization, sulfa drugs.
• Power: Electric motor, hydroelectric power, internal combustion engine, secondary battery, steam turbine.
• Transportation: Airplane, automobile, high-speed road system, primitive helicopter, zeppelin.

TL7:

The Nuclear Age dawns with the successful harnessing of nuclear power (in the 1940s, on historical Earth). This occurs alongside such inventions as television, jet engines, and the transistor. The crowning achievement of TL7 technology is in many ways to make good on the promises of TL6. Significant innovations include:

• Agriculture: Chemical fertilizer, hybrid crops.
• Arms and Armor: Assault rifle, ballistic body armor, guided missile, military helicopter, military jet, nuclear weapons.
• Information Technology: Computer, high-speed press, television.
• Machinery: Integrated circuits, laser, transistor.
• Material Science: Composite materials, plastic, superconductors, titanium.
• Medicine and Health: Artificial heart, organ transplants.
• Power: Gas turbine, nuclear power, photovoltaic cell.
• Transportation: High-speed train, jet aircraft, spacecraft.

TL8:

The Digital Age begins with the commercial success of personal computing – in around 1980, here on Earth. Definitive technologies include:

• Agriculture: Genetically engineered crops and pesticides.
• Arms and Armor: Bioengineered disease, personal defense weapon, stun gun, unmanned drone.
• Information Technology: Desktop publishing, personal computer, Internet.
• Machinery: Rapid prototyping.
• Material Science: Carbon fiber, fullerenes, microfibers.
• Medicine and Health: Artificial fertilization, genetic screening, laser surgery.
• Power: Advanced battery, computer-integrated power plant, wind farm.
• Transportation: Hybrid car, reusable spacecraft.

TL9: The Microtech Age

Major advances occur in the material science, especially in the fabrication of nano-scale materials, the development of composite materials, and in polymer-based electronics. This leads to the widespread use of devices such as printed computers, flexible batteries, and bio-compatible implants, as well as products such as video wallpaper and chameleon suits.

Micro-mechanical electromagnetic systems – tiny sensors and actuators – drastically shrink many electronic and mechanical devices. The results are dramatic, ranging from vehicle surfaces that can change their aerodynamic properties to labs-on-a-chip and artificial gills.

Fuel cells and gas turbines are miniaturized and used as power cells for electronics and other portable devices. On a larger scale, nuclear fusion and solar power free society from dependency on fossil fuels, although they may remain economically important.

Computers, sensors, and communicators are faster, smarter, and smaller, and can be built into almost anything. Wearable computers are inexpensive.

Quantum computers can solve problems and break encryption by computing every possible solution at once, but quantum communication systems trump that with unbreakable encryption. Neural interfaces link mind and machine, and cybernetic implants do not merely replace injured body parts, but actually enhance them.

Mobile robots are commonplace, used in everything from nursing to vehicle operation to combat. However, they lack self-initiative, and many are teleoperated. Androids that can look human (even if they don't act human) are expensive but available.

Improvements in material technology lead to affordable space transport systems, such as single-stage-to-orbit shuttles or space elevators. Cheaper access to orbit may boost other space technology, such as nuclear engines for interplanetary journeys, beamed power from solar satellites, and life support technology. Industry and even colonists may go into space, taking advantage of the gravity-free environment to mine asteroids or develop better industrial processes.

Small arms technology still relies on conventional guns (with improved ammunition and smart electronics) but specialized non-lethal energy weapons such as electrolasers and sonic nauseators appear. So do the first bulky laser sniper rifles, heavy electromagnetic railguns, and laser cannon.

Antimatter is now routinely manufactured. It's used in medicine (as a radiation source) but is too expensive to be used as a fuel or explosive. It is still useful in space propulsion and weaponry, as a catalyst for triggering "clean" nuclear explosions. Mini-nukes increase the risk of nuclear war by blurring the boundaries between conventional and nuclear arms.

Body armor advances even more rapidly than weapons. Comfortable climate-controlled suits can protect the entire body, and space suits become lightweight vacc suits. Advances in micro-turbines and robotics make powered suits feasible, both exoskeletons (for civilian and military applications) and battlesuits.

Perhaps the most significant developments are in bioscience. Functional organs can be grown with tissue engineering and transplanted into the body. Wonder drugs and other treatments can be delivered in smart capsules. Not all diseases are cured, but lifespans may increase substantially.

Superscience: Monomolecular wire and plasma weaponry are developed. It's common for faster-than-light drives, parachronic travel, reactionless drives, or other superscience transport systems to appear. TL9 cultures can spread out rapidly to other worlds.

TL10: The Robotic Age

Artificial intelligence becomes smarter and cheaper, and the first volitional AIs – machines that can think like people – appear. Inexpensive sapient machines are commonplace. Swarms of tiny microbots can be built, and biomechanical nanomachines can perform prodigious feats of medicine and genetic engineering.

People who can afford to take full advantage of TL10 medicine may live for centuries or more. As science gains a greater understanding of the human mind, more complex neuro-tech and cybernetics become available...it's possible to cybernetically possess bodies, control minds, and record sensory information.

Molecular nanotechnology is routinely used in manufacturing. Many products can be self-assembled "from the bottom up" using methods analogous to the way biological organisms grow. The tools used are biomechanical in nature, combining proteins and engineered viruses with metals and other inorganic materials. Bio-nanomachines construct most biotech products and are used in medicine and genetic engineering, but molecular manufacturing is still limited to making specialized components and products that can be assembled in "wet" environments. Macro-scale products using metals, semiconductors, diamond-hard materials, and ceramics still rely on "top down" manufacturing techniques.

One example of the new bio-nanotech products is pseudo-alive polymers that are capable of self-repair. These "living bio-plastics" make a range of tough, lightweight, and self- maintaining equipment possible.

Material and power generation technology continues to improve. Super-strong composite materials are relatively inexpensive. Weapons technology takes a quantum leap with the development of power cells that can power effective man-portable electromagnetic guns and high-energy lasers, although conventional weapons may remain in use with smarter ammunition. Nuclear fusion reactors are small enough to power battle tanks and fighter-sized spacecraft.

Superscience: Gravity control technology leads to artificial gravity and contragravity being used in personal vehicles, houses, and weapons, as well as reactionless space drives. Nuclear dampers can neutralize the threat of nuclear weapons. New superscience weaponry becomes available, notably plasma guns and exotic sonic beams.

TL11: The Age of Exotic Matter

Technology achieves precise control over the atomic structure of objects. A mature molecular nanotechnology is available, capable of inexpensively fabricating most products with atomic-level precision. Nanofactories make products out of diamond-hard material ("diamondoid").

Not everything can be built in nanofactories, however. The most advanced TL11 products tinker with the sub-atomic structure of matter to create exotic materials. This may involve replacing electrons with super-massive particles (such as muons) to create hyperdense matter. Depending on its stability, this may be used as a catalyst for fusion reactions (resulting in more compact power plants), or as a component in computer hardware, armor, and other equipment.

Antimatter is another exotic material that comes of age at TL11. As its price of manufacture drops, it begins to see use as a means of compact energy storage. Antimatter rocket engines are also available.

A vast array of powerful beam weapons are now available, including portable particle beams (blasters) and X-ray lasers. In response, armor becomes stronger and smarter, and is usually made of diamondoid composites and exotic alloys. Most armor is powered, from skintight smartsuits to nuclear-powered dreadnought battlesuits.

Nanotechnology dominates medicine. The standard way to heal someone is to take him apart (using the chrysalis machine) and put him back together again in perfect condition. Minds can be copied without destroying the original body.

Superscience: Contragravity is miniaturized, resulting in personal flying belts and small, hyper-agile robot missiles. Force screen generators protect vehicles and installations, but are not yet suitable for personal use. Ranged gravity projectors are available, leading to tractor and pressor beams and gravitic weapons. Hypergravity technology can produce stabilized hyperdense armor and compact nuclear reactors. Matter transmission can teleport people from place to place, as long as there is hardware to send and receive. Superscience sensors can "scan" for just about anything, and even see through walls. Ranged neurotech devices such as dream nets and neural disruptors are introduced. Recorded minds can be played back into living bodies.

TL12: The Age of Miracles

TL12 societies use their understanding of the universe to produce devices and effects that are incomprehensible to less advanced cultures. The TL11 advances in nanotechnology and exotic matter are fully integrated into civilization, along with new devices such as living metal, gamma-ray lasers, and self-replicating nanomachine swarms.

Simple pills can regenerate the body in a matter of hours, or grow new cybernetic implants a matter of days. Pocket antimatter reactors power vehicles, and spaceships and cities run on total conversion of mass to energy. Entire planets can be moved, or disassembled to build a shell around a star. Devastating personal weapons are developed, while nanomachines can directly imprint consciousness into human brains.

Most aspects of a TL12 civilization can be run by intelligent machines, and most people might be machines, whether wholly or in part. Sentient robots could reproduce themselves rapidly, spreading like a plague to terraform (or eat!) a planet in a matter of months, or build any industry that is required. Raw materials are easy to come by. While asteroid belts may be already used up, TL12 cultures can dismantle Jupiter-sized gas giants for parts.

Of course, if several TL12 nations existed in the same area and no one wanted to leave, they would soon run out of gas giants. Then things might get nasty...

Superscience: Matter transmitters can "beam up" or "beam down" without a receiving booth at the other end. Regeneration rays may supersede nanotechnology for rapid treatment of injuries. Force fields can alter the flow of time. Disintegrators and reality disruptor weapons can destroy almost any target that is not protected by superscience defenses. Fortunately, personal force fields and stasis fields can stop them.

Even Higher TLs

Incredibly advanced technologies are difficult to conceptualize, never mind use in play. Even so, it's hard to resist the question of "What’s next?"

One option is to assume an age of technological stagnation sets in. TL12 science may answer all the fundamental questions of the universe, and technological progress may not be possible. There is no TL13; science catalogs what exists rather than explaining it. Engineering is no longer about invention, but merely application.

Another possibility is to continue a straight-line progression. TL13 devices are like TL12 but weigh or cost half or two-thirds as much, and so on. Or superscience developments can have their TL bumped up to TL13+. They may represent bold new inventions, or artifacts from civilizations that ruled the galaxy eons ago.

Variant Paths

Ages of Technology (above) offers a rough "average" of progress through history and prehistory, based on the ancient Near East, Greece, Rome, and Europe. Elsewhere in the world, technology evolved differently. Often it was slower; Paleolithic societies existed at the start of the 20th century! Occasionally it was faster. Define a society's TL by the tools and techniques in common use there – not by the calendar date.

Different technologies don't always advance in step. Some societies achieve a TL's overall capabilities without all of its characteristic technologies – and sometimes without its signature technology! Variant societies can be described as "retarded in a science." A society can also be "advanced in a science," having one set of techniques usually found only at a higher TL; it might even jump from an early technology to a far more advanced one, skipping everything in between. And it's quite possible for a society to be advanced in certain technologies but retarded in others. In extreme cases, a society's TL may be a rough average of capabilities representative of three or four TLs. Judge a society's TL by its overall function, never on the strength of a single technology.

Some examples:

Polynesian Navigators: The Polynesians had Stone Age technology overall, with pre-state social organization and without literacy. But they built boats with sails that could cross the Pacific, and developed navigational methods to guide their voyages. Treat them as TL0 with TL2 seafaring.

The Walls of Jericho: Archaeologists working at the site of Jericho discovered that its oldest relics date to 7000 B.C., in the late Neolithic. The original city covered 10 acres and had massive walls surrounded by a ditch. Its 2,400 inhabitants supported themselves by Neolithic farming and gazelle hunting. Jericho is TL0 with TL1 construction and fortification.

Mayan Astronomers: The Maya were the New World's first civilization, building stone cities and keeping written records. But they didn't have bronze, used few metal tools, and had no draft animals. On the other hand, their mathematics was sophisticated, with a symbol for zero; so was their astronomy. Treat them as TL1 with TL0 materials and TL3 mathematics.

African Metallurgy: The kingdoms of Sub-Saharan Africa didn't pass through a distinct Bronze Age; their metallurgy went straight to iron. But they were otherwise organized like Bronze Age civilizations. Treat them as TL1 with TL2 metallurgy.

Medieval Medicine: In many branches of technology, medieval Europe was more advanced than the Roman Empire, from three-course crop rotation to weapons and armor. But for most of the Middle Ages, it didn't support professional doctors, and it failed to advance beyond the Roman Empire in medicine – and in some ways fell behind it. Treat medieval Europe as TL3 with TL1-2 medicine.

Chinese Advances: Europe entered TL4 around 1450. But in the Middle Ages, Europe wasn't the most technologically advanced society on Earth. Between 1000 and 1450, China developed cast iron; the magnetic compass; mechanical clocks; large seagoing junks that traveled as far as southern Africa; the printing press; paper money; and black powder. It's plausible to put the start of TL4 earlier in China – perhaps in 1250, during the Mongol invasions.

Alternative Technologies

What about making up technological patterns – those of wholly fictional cultures, or ones that might have arisen had the history of technology gone differently? The resulting technologies are unlikely to match historical examples perfectly, and probably won't precisely fit the stages that define TL0-4.

Roads Not Taken

An imaginary society may advance unusually quickly in one technology, developing inventions that historical societies didn't achieve until much later. Such societies can be described as "advanced in a science or art" (see Variant Paths, above). For example, if a society comparable to ancient Rome had set aside its prohibitions against dissection and discovered blood circulation, it would have been TL2 but advanced in medicine.

A society may develop technologies that were never made workable in the real world, advancing along a different path. Such societies can be described as having a TL such as TL(0+1) or TL(3+1). The +1 means that they brought into regular use inventions that the real-world society that inspired them failed to perfect. For example, ancient Roman armorers experimented with compressed-air cylinders to store energy in catapults; if they had achieved a tight enough seal, the result might have been a TL(2+1) society.

Low-Tech gives relatively little attention to such imaginary TLs. It doesn't consider magical technologies, different laws of nature, or the speculations of people in historical societies. It does discuss a few inventions that weren't fully developed, asking what would have happened had they been brought into regular use; such inventions define TLs from TL(0+1) to TL(4+1). Low-Tech also notes some inventions that speculative historians and archaeologists suppose might have been achievable by past societies, if they've been shown to be achievable with those societies' resources. For example, Thor Heyerdahl's raft boat that crossed the Atlantic could have been built with Egyptian materials and methods, although most Egyptologists don't believe this really happened.

Blocked Roads

Another option is to assume that a society attained some level of technology without all of the usual key inventions. For example, many science-fiction writers describe societies that advance rapidly in biotechnology while the physical sciences stagnate. A civilization without access to useful ores might work with stone, ceramics, glass, and hardwoods in lieu of metals.

Pastoral nomads are an interesting variation on this theme. Historically, almost all forms of pastoralism were offshoots of agriculture (reindeer herding is the exception). Thus, pastoralists are TL1 to TL3, despite lacking agriculture, cities, and bureaucracy. Their military technology is often formidable – the Bedouin and the Mongols created huge empires by conquering their civilized neighbors.

Technology for Nonhumans

Yet another way to have technology develop differently is to make its users members of a nonhuman species. Just being larger or smaller can require differently designed gear; see Adjusting for SM and the scaling rules in GURPS Low-Tech Companion 2.

Alternative manipulators, such as an elephant's trunk or a parrot's beak and claws, could require unconventional tool designs. And what if the race relies on a primary sense other than sight, lacks a human sense, or possesses a sense that humans don't, such as a bat's sonar? What if it can affect its environment by means other than muscle contractions, such as an electric eel's discharges?

A race's native environment will also play a role in its technologies. Aquatic beings won't have fire and will make little use of metals. Flying ones will probably avoid heavy equipment, but may be quick to develop navigation and optics.