Imagined in the 1920s

A large prize. A working vessel for travel between worlds would found a transport industry of its own.

Who is paid. Carriers and expedition firms buy ships, and many yards could build them once shown how, so established vehicle builders collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. It is a part of a suit, useful to the wearer but not a product by itself.

Who is paid. Space operators pay for it within the suit, and the established suit makers supply it since any of them can copy it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. It keeps a person alive and able to work outside, essential gear but only for the few who work in space.

Who is paid. Space operators buy suits for their crews, and the few established makers of suits can all copy a design, so they collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A working engine for travel between worlds sets the cost of every voyage it powers.

Who is paid. Ship operators pay, and once the engine was shown to work others could build it, so established engine builders collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. It is a necessary fitting on any crewed craft, but only a part of the ship.

Who is paid. Ship operators pay for it within the craft, and shipbuilders make it themselves since nothing stops others copying it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Clearing dangerous rocks keeps space routes safe, a useful service but only a support to the traffic.

Who is paid. No single ship could be charged for a clear route, so a government pays, and operators that already hold armed ships and such contracts do the work.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Warning of rocks ahead keeps a ship safe, but it is a fitting on the craft, not an industry.

Who is paid. Ship operators pay for it within the craft, and the firms that already make ship instruments supply it since the design can be copied.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. It is a term for the planet a people came from, not a product.

Who is paid. Nothing is sold, so nobody pays and no seller collects.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. It is a word or a way of doing things that needs no new equipment, not a product.

Who is paid. Nothing is sold, so nobody pays and no seller collects.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A suit that keeps a person alive in vacuum or thin air is vital to its wearer but serves only the few who work in space.

Who is paid. Space operators buy suits for their crews, and the few firms that already make such gear supply them since the design can be copied.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A spaceship a private person can own and fly would open a new kind of private travel.

Who is paid. Private owners buy the ship; the description says only a private party, assumed here to be people and not firms, and since the design could be copied the established builders of craft collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A marker in space for navigators is a minor aid to navigation.

Who is paid. A beacon serves all ships and none can be charged, so a government pays, and a simple transmitter or light is something many firms could build.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. It is a word or a way of doing things that needs no new equipment, not a product.

Who is paid. Nothing is sold, so nobody pays and no seller collects.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. Moving a whole star would decide the fate of every world around it, which is assumed here to mean saving or resettling whole peoples.

Who is paid. Only a government could fund work on that scale, and the large engineering firms that already hold such contracts would be paid to do it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A panel for plotting courses between stars is essential to the voyage but is an instrument within the ship.

Who is paid. Ship operators buy it as part of the craft, and the established makers of flight instruments supply it since it can be copied.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Safe cooking aboard ship is a comfort for crews, a small fitting.

Who is paid. Ship operators pay for it within the craft, and appliance and galley makers could all supply it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A suit that keeps a person alive in vacuum or thin air is vital to its wearer but serves only the few who work in space.

Who is paid. Space operators buy suits for their crews, and the few firms that already make such gear supply them since the design can be copied.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Steering whole rocks to where they are wanted would serve mining and building in space, part of an industry of its own.

Who is paid. Mining and building firms are assumed to pay, and fixing engines to a rock is easy to copy, so the firms that already own ships and engines collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Using a handgun's kick to move while weightless is a makeshift version of a niche tool for a few workers.

Who is paid. Space operators buy it for their crews, and the makers of suits and space gear supply it because it is easy to copy.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Steering whole rocks to where they are wanted would serve mining and building in space, part of an industry of its own.

Who is paid. Mining and building firms are assumed to pay, and fixing engines to a rock is easy to copy, so the firms that already own ships and engines collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Weight underfoot on any ship would be fitted almost everywhere people live in space, assuming here a generator and not a spinning hull.

Who is paid. Ship and station operators buy it, and once it worked other makers could copy it, so established builders collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Pushing craft with a beam of light from a far-off station would let ships fly without carrying their own fuel.

Who is paid. Ship operators pay for the push, and since others could build beam stations the gain goes to those who already own the sites and power plants.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

No prize. It is a name for our own star, not a product anyone makes or sells.

Who is paid. Nothing is sold, so nobody pays and no seller collects.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A working vessel for travel between worlds would found a transport industry of its own.

Who is paid. Carriers and expedition firms buy ships, and many yards could build them once shown how, so established vehicle builders collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Travel that needs no fuel would cut the cost of moving ships and cargo across space.

Who is paid. Ship operators buy the sail as their engine, and a thin reflecting sheet is something other makers could copy, so established ship builders collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Carrying people between worlds would be a transport industry of its own; it changes life for those who go, not for most people.

Who is paid. Carriers buy the ships and sell the passage, assumed here as with other ships, and since ships can be copied the builders and carriers that already own fleets and ports collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Checking that suits hold before crews rely on them is a needed routine, part of making and keeping suits.

Who is paid. Suit makers and space operators pay for the test gear, and the established makers of suits and test equipment supply it since it can be copied.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. A machine that truly thinks could do much of the mental work people do now, which would change how most people work.

Who is paid. Firms would pay to put it to work, and once one had been built others could learn to build their own, so I assume the firms that already own costly computing plant and sell to every business collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Machines that can see make possible inspection, driving, sorting and watching without a person.

Who is paid. Firms buy it inside their machines, and the methods spread quickly, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Fast sums in the hand or on the desk are a convenience for people who calculate.

Who is paid. Firms and students buy them, and anyone can make one, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. A machine that truly thinks, whatever chemistry it runs on, could do much of the mental work people do now, which would change how most people work.

Who is paid. Firms would pay to put it to work, and once one had been built others could learn to build their own, so I assume the firms that already own costly computing plant and sell to every business collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Hearing through the skull bones helps some people with poor hearing and suits a few uses, but for most it is one more kind of earphone.

Who is paid. People buy it for themselves and the vibrating part is simple to make, so many firms sell it and none keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Hearing your messages from anywhere is a convenience.

Who is paid. Phone users pay; it is easy to copy, so the firms that own the phone networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Beaming power as well as data through the air would free devices from plugs and batteries, which goes well beyond the real thing that only carries data.

Who is paid. Households and firms pay for the service, and since the method could be copied, the firms that already own the power lines and networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A radio worn on the chest that sends whenever you speak is a hands-free tool for teams, not a phone for everyone.

Who is paid. Unlike a pocket phone on a public network, this is a short-range team radio that work crews and soldiers would be issued, and many firms can make it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Seeing the person you are talking to is something most people now use, and it is worth an industry.

Who is paid. Ordinary people pay for the device and the line, and since many can make the device, the firms that already own the phone networks and handset brands collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Earpieces that shut out background noise are a comfort many like but few need.

Who is paid. People buy them for themselves and small earpieces are simple for many firms to make, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Letting both sides talk at once is an improvement to radio sets that already exist.

Who is paid. Operators of ships and aircraft buy the sets, and since many can make them, no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Seeing the person you are talking to is something most people now use, and it is worth an industry.

Who is paid. Ordinary people pay for the device and the line, and since many can make the device, the firms that already own the phone networks and handset brands collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A thin screen for the wall is the form nearly every display now takes and is an industry of its own.

Who is paid. Households buy the sets, and since any electronics factory could copy the design, the firms that already own the factories, brands and shops collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A finished print in moments is a convenience over waiting for film to be developed.

Who is paid. People buy the camera and the film, and once the trick of a self-developing print is known other camera makers could copy it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. An artificial world that feels real would be worth an entertainment industry of its own; I judged the full promise, which is larger than anything sold so far.

Who is paid. Ordinary people buy it; the machine can be copied once shown, so those who already own the stories and worlds people want to enter collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. The best teachers reaching every student would cut the cost of schooling; I judged the promise, which is larger than what was built.

Who is paid. Assuming students and families pay for the lessons themselves, and since a school subject belongs to nobody the way a novel or a song does and no certificate is described, anyone can record and sell lessons, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Paying to watch a live match at home is worth an industry of its own.

Who is paid. Viewers pay; the sending is easy to copy, so those who already own the sporting events and the broadcast networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. Seeing distant events live at home changed how most people spend their evenings and learn the news.

Who is paid. Households buy sets and pay for channels, and since sets are easy to copy, the firms that own the factories, the stations and the networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Unlike the first television sets, this is a thinner form of a set people are assumed to have already, so the gain is a better screen, which is an industry of its own.

Who is paid. Households buy the sets, and since any electronics factory could copy the design, the firms that already own the factories, brands and shops collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. Seeing distant events live at home changed how most people spend their evenings and learn the news.

Who is paid. Households buy sets and pay for channels, and since sets are easy to copy, the firms that own the factories, the stations and the networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. A manufactured worker able to do what people can do would change how most people work.

Who is paid. Firms buy them as labour, and since many could build such bodies once shown how, the large manufacturers with factories and service networks collect what is left.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A vast prize. The description gives only a woman's shape, so it is judged as the artificial worker of the stories, which would change how most people work.

Who is paid. Firms buy them as labour, and since many could build such bodies once shown how, the large manufacturers with factories and service networks collect what is left.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A remote or flexible gripper is a useful tool for awkward jobs, but a niche.

Who is paid. Firms buy it for their own work, and such grippers and controls are easy for many makers to copy.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. The description gives this giant rolling machine no job, so it is judged as a heavy carrier of unusual shape, a niche.

Who is paid. Firms moving heavy loads are assumed to buy it, and as many could copy the shape the makers of heavy equipment with factories collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. The description gives these huge machines with snaking arms no job, so they are judged as heavy handling machines of unusual shape, a niche.

Who is paid. Firms doing heavy work are assumed to buy them, and as many could copy the shape the makers of heavy equipment with factories collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Reliable care for infants and young children at home would be worth an industry of its own.

Who is paid. Families buy it, and since they are assumed to trust only known names with their children the established makers with strong brands collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Typing orders to a distant robot is a way of working a machine from afar, a useful tool but a niche.

Who is paid. Firms buy it for their own work, and such controls are easy for many makers to copy.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A giant claw that can seize and hold a person is a gripper with few uses, assumed here to be for handling and rescue work.

Who is paid. Firms buy it for their own work, and such grippers and controls are easy for many makers to copy.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Humanlike machines steered from afar keep people out of danger in a few hazardous trades.

Who is paid. Firms with dangerous work buy them, and such machines and their controls could be copied by many makers.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A machine that lets a distant operator see, hear and act in a place is a useful tool for some jobs, and the real thing exists as a niche.

Who is paid. Firms buy it for their own work, and such machines and their controls could be copied by many makers.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A console showing the view from each of many robots is a control tool, valued as part of running them.

Who is paid. Firms buy it for their own work, and such controls are easy for many makers to copy.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. Machines pushing people out of paid work is a result of other technologies, not a technology that could be sold.

Who is paid. Nothing is sold here; the working robots themselves are judged under their own names.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Legs that let a landed spacecraft walk are a feature of the craft, handy on rough ground.

Who is paid. Operators of spacecraft, assumed here to be firms, pay for it within the price of the craft, and any shipbuilder could fit it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Huge walking machines that dig and move soil would cut the cost of earthworks and mining.

Who is paid. Mining and building firms buy them, and since many could build them the heavy-equipment makers with dealers and repair networks collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Replacement body parts made in quantity would be worth an industry of their own to the many whose organs fail.

Who is paid. Patients would pay, mostly through insurers or health services, and several firms could run such factories, so established medical makers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Building living things from plain chemicals would give farming, medicine and industry organisms made to order.

Who is paid. Firms would buy such organisms for their work, and once the method was known other laboratories could repeat it, so established chemical and drug makers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A hat that keeps its wearer steady is a novelty.

Who is paid. Wearers would buy it, and any workshop could fit a spinning wheel into a hat, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Carrying a child outside the body would spare mothers the risks of pregnancy and open parenthood to people who cannot carry a child.

Who is paid. Would-be parents would pay, and other laboratories could copy the chamber once it worked, so established fertility clinics collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Staying alert on too little sleep is something a great many workers, drivers and students would use.

Who is paid. People would buy it for themselves, and stimulants of this kind are old chemistry many firms can make, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Making cells multiply faster would speed healing and the growing of tissue for medicine.

Who is paid. I assumed hospitals and laboratories buy it; an electrical device of this kind could be copied, so established medical equipment firms collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. The story promises only a little energy from sunlight, which is a curiosity beside ordinary food.

Who is paid. I assumed people buy it for themselves from clinics; the method could be copied, so clinics already offering such treatments collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Keeping your own thoughts to play back later is a notebook that needs no writing, a convenience.

Who is paid. The user records their own thoughts, so people would buy it for themselves, and many makers could copy it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A machine body for a living brain would give the dying more years, though few would choose such a life.

Who is paid. The dying and their families would pay, and hospitals and makers of medical machinery could copy it and collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Letting a doctor feel what the patient feels is one more aid to diagnosis among many.

Who is paid. Hospitals and clinics would buy it, and the makers of medical equipment who already sell to them could copy it and collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Showing others what you remember or picture is a new kind of camera, a pleasure and a keepsake rather than a need.

Who is paid. Unlike the probes used on unwilling subjects, I assumed this headset is worn by a willing person to show their own recollections, so ordinary people would buy it, and once one maker had it others could copy it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

No prize. As described it is a merging of minds with no made device behind it, a way of being and not a product.

Who is paid. I assume nothing made or sold causes the merging, since the description names none, so there is no buyer and no seller.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Free personal flight with no limit stated would be an industry of its own, replacing many trips now made by car.

Who is paid. Riders buy it for themselves, and a light craft like this could be built by many workshops once the trick is known, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. An aircraft that flies very fast with almost no limit on range would change the costs of long-distance flight.

Who is paid. Airlines and freight carriers buy the aeroplane, and it is judged as a craft, not as its power source, so the aircraft makers that already build and service fleets collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A little vehicle for indoors and the street helps people who find walking hard, and is a convenience for others.

Who is paid. Riders buy it, and many firms can make a small electric cart, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A rig that lets a person fly wherever they please, working as promised, would be an industry of its own as the motorbike is; the description gives no limit on range or weather, so I assume there is no such limit.

Who is paid. Riders buy it for themselves, and a light craft like this could be built by many workshops once the trick is known, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Hired flight across a city, working as promised, would be an industry of its own beside road cabs.

Who is paid. The carrier or fleet operator that runs the air cab buys it and charges riders, and since several firms could build it, the makers that already build and service such craft collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A railway carried through the sky would cross rivers, hills and cities without land or tunnels, changing the cost of building lines.

Who is paid. Governments pay for railways on this scale, and the builders that already hold such contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Flying goods between distant cities is an industry of its own that made fast long-distance delivery ordinary.

Who is paid. Freight carriers buy the aircraft, and since any large builder can make a cargo plane, the builders and carriers that already own the factories and fleets collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. The description gives only a different way of staying aloft, so I assume it does what other aircraft already do.

Who is paid. Airlines would buy it, and the established aircraft builders collect because a new lifting method can be copied once shown.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A flat panel that lifts and holds still in the air is a small flying raft, useful for odd jobs and short hops rather than everyday travel.

Who is paid. Riders buy it for themselves, and a light craft like this could be built by many workshops once the trick is known, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A clock that shows the hour of the ground below is a handy extra for crews and passengers.

Who is paid. Airlines buy it with the aircraft, and any instrument maker could build it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A lighter-than-air craft is slow and carries little beside aircraft and trains, so it stays a niche; this one is built for long exploring flights.

Who is paid. Operators buy it, and airships are simple enough for many builders to make, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A screen showing where many aircraft are is a needed tool for those who direct air traffic, and few buy it.

Who is paid. Governments run air traffic control and pay for it, and the electronics firms that already hold those contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Nets round the rim of a huge aircraft are a safety fitting.

Who is paid. The operator of the aircraft buys them, and netting is simple to make, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A plane that folds small enough to carry puts flight in private hands, and the description states no limit on where it can fly, so it is judged with the free personal flyers as an industry of its own.

Who is paid. Riders buy it for themselves, and a light craft like this could be built by many workshops once the trick is known, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Plentiful power from a little fuel would change what electricity and heavy transport cost.

Who is paid. Power and transport firms buy it, and because governments let only a few hands hold nuclear fuel, the few permitted makers keep what is left.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. Running a small device on stray energy saves a battery, which is a convenience.

Who is paid. People buy it inside small gadgets, and any gadget maker can add it so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Sunlight gathered near the sun and sent to cold planets would supply whole settlements that have no other source.

Who is paid. Only governments could fund a work this size for whole settlements, and whoever builds the one station controls a supply nobody else can match.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Lamps that match daylight are a nicer light, which is a convenience.

Who is paid. People buy them for homes and shops, and any lamp maker can produce them so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Light that wastes almost no power as warmth changes what lighting costs everywhere.

Who is paid. Building owners and lamp fitters buy it, assumed here to be the main buyers, and many factories can make it so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Tiny modules that join into larger structures by themselves would change the cost of construction.

Who is paid. Builders buy them, and once they can be copied the established makers of building materials collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

No prize. It is a joke element with no stated use, so there is nothing for anyone to buy.

Who is paid. Nothing is sold, so nobody pays and no seller keeps anything.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A metal with the strength of heavy metals at far less weight would cut the weight and running cost of aircraft, ships and structures.

Who is paid. Vehicle and building firms buy it, and a metal recipe gets copied, so the established metal makers with furnaces and customers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A substance that cannot be seen at all would be prized for hiding soldiers, craft and equipment.

Who is paid. Governments pay, assuming hiding is its main use, and the firms that already hold military supply contracts make it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A very thin, very strong wire would change the cost of cables and structures; being too fine to see does not alter that.

Who is paid. Builders and vehicle makers buy it, and once the method is known the big materials firms with plants and customers make it and collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A borer that also turns the spoil into building material would change the cost of tunnels and mines.

Who is paid. Mining and building firms buy it, and makers of heavy digging machines who already sell to them can copy and supply it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A strong metal of extraordinary lightness would cut the weight and running cost of aircraft, ships and structures.

Who is paid. Vehicle and building firms buy it, and a metal recipe gets copied, so the established metal makers with furnaces and customers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. True invisibility would be worth a great deal to armies and spies, and would likely be kept from ordinary buyers.

Who is paid. Armies and spy services pay, and the firms that already hold their equipment contracts would make it once the method is known.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Boots that grip metal help the few who work on hulls and steel frames.

Who is paid. Employers buy them for their workers, and any bootmaker can fit magnets to a sole.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A see-through material with the strength of metal would change how windows, vehicles and buildings are made.

Who is paid. Builders and vehicle makers buy it, and once the method is known the big materials firms with plants and customers make it and collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Finding and naming buried metals from the surface would change the cost of prospecting for the whole mining trade.

Who is paid. Mining firms buy it, and an instrument can be studied and copied, so established instrument makers and survey firms collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Assuming a soldier carries it, it does much the same job as a gun, so the gain over a gun is modest.

Who is paid. Armies buy it with public money, and since rival makers can copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Assuming a soldier carries it, it does much the same job as a gun, so the gain over a gun is modest.

Who is paid. Armies buy it with public money, and since rival makers can copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Judged as if it worked, a weapon that surely stops a person at a distance without harming them does what no gun can, and police and guards everywhere would carry it in place of firearms.

Who is paid. Police forces and armies buy it with public money, and since rival makers could copy it once it was shown, the suppliers that already hold their contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A heavy beam that can strike ships or aircraft at the speed of light would reshape how fleets are armed and defended.

Who is paid. Armies buy it with public money, and since rival makers can copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Judged as if it worked, a weapon that destroys whatever it strikes leaves no armour, wall or hull able to protect, which would change how wars are fought.

Who is paid. Armies buy it with public money, and assuming rival makers learn to copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Assuming a soldier carries it, a gun that throws splinters faster than any other still does the job guns already do.

Who is paid. Armies buy it with public money, and assuming rival makers learn to copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Judged as if it worked, a field that hides whole ships or bases from watchers would change how forces are found and struck.

Who is paid. Assuming it is bought to hide forces in war, governments pay, and assuming rivals learn to copy it the established arms suppliers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Unlike a device for hurting a held prisoner, a beam that drives off free people through pain is a weapon police may lawfully carry, but it only moves a crowd along, a niche.

Who is paid. Police and prison services pay, and the firms that already supply them would add it to their range and collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A launcher one soldier carries is one more kind of firearm, a modest step over the guns armies already have.

Who is paid. Armies buy it with public money, and since rival makers can copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A weapon that can end a war or prevent one is worth a great deal to the state that holds it.

Who is paid. Only governments pay for it, and only the handful of builders a state allows near the material may make it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Judged as if it worked, a weapon that destroys whatever it strikes leaves no armour, wall or hull able to protect, which would change how wars are fought.

Who is paid. Armies buy it with public money, and assuming rival makers learn to copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Judged as if it worked, a barrier that stops attacks would change how ships, bases and cities are defended.

Who is paid. Assuming it is bought for defence in war, governments pay, and assuming rivals learn to copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Judged as if it worked, and assuming a soldier carries it, a beam that shoves or strikes does much the same job as a gun.

Who is paid. Armies buy it with public money, and assuming rival makers learn to copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A beam weapon carried in the hand does much the same job as a gun, so the gain over a gun is modest.

Who is paid. Armies buy it with public money, and since rival makers can copy it the established arms suppliers with standing army contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A better way to overhear people is a specialist tool for police and spies, not a wide market.

Who is paid. Police and spy services pay, and it is easy to copy, so the firms already supplying them collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A camera in the air sending back pictures from overhead changes what an army or police force can see.

Who is paid. Spy and police services pay, and once made it can be copied, so the firms already supplying such services collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. A token carrying a person's whole file is a sturdier identity paper, a convenience for the authority that issues it.

Who is paid. Whoever issues the credential pays, assumed here to be a state, and the firms that already make official papers and registers collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Compact rations are a convenience for people who cannot carry or cook ordinary food.

Who is paid. I assumed armies and state expeditions are the main buyers, and the firms that already hold their supply contracts collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. Opening a door by voice saves carrying a key, which is a convenience.

Who is paid. Households buy it and any lock maker can build it, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A small prize. It makes coffee, which ordinary heat already does well.

Who is paid. Households buy it, and the story has it sold freely, so I assumed any appliance maker may buy the radioactive source and build the same thing, and no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A nappy that says when it is wet saves parents some checking.

Who is paid. Parents buy it, and the signal is easy to add, so the nappy brands that already fill the shop shelves collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Housing a whole town with its work and services in a single structure is a building project on the scale of an industry.

Who is paid. Residents buy or lease the homes and shops inside, as they would in any large development, and since others could put up such a structure the developers and landowners who already hold the sites collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A glass-roofed promenade is a pleasant shared space inside a giant building.

Who is paid. The building owner pays for it, and anyone can build a glass roof, so the developers who already hold the building collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Speeding or slowing one's own time would be worth a great deal to the person who has it.

Who is paid. I assume it is fitted like a medical implant for private buyers, and that once one firm made it others could, so the makers and clinics that already fit implants collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Judged as the visit the description allows: a way into another world could open new lands and materials, though what lies beyond is unknown.

Who is paid. I assume a state would claim the way across and explore it like a space programme, paying its usual contractors to do the work.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. More room inside the same walls would cut the cost of housing where land is scarce.

Who is paid. Households would buy it, and since the coating could be copied the paint and building firms with factories and shops collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. A worker who can shrink or grow could repair, inspect and operate where no tool reaches.

Who is paid. I assume hospitals and engineering firms buy it for staff, and a wearable device could be copied by many makers once shown.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Cooling at a distance would change refrigeration, firefighting and heavy industry.

Who is paid. Factories, food firms and fire services would buy it, and makers of cooling equipment would sell it once the method was known.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Personal flight without wings or fuel would be a new kind of everyday travel, though a narrower use than lifting freight and vehicles.

Who is paid. Ordinary people would buy it as they buy bicycles, and once one firm made it many could, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Gripping and moving things at a distance would change towing, cargo handling, building and rescue.

Who is paid. Ports, builders and ship operators would pay, and with the method open to copying, makers of cranes, tugs and handling gear would collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A beam that takes anything apart would be a decisive weapon and a tool for demolition.

Who is paid. Armies would be the first buyers, and the arms makers that already hold their contracts would supply it.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Personal flight without wings or fuel would be a new kind of everyday travel, though a narrower use than lifting freight and vehicles.

Who is paid. Ordinary people would buy it as they buy bicycles, and once one firm made it many could, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Cancelling weight at will would cut the cost of lifting, carrying and launching, which changes transport and building more than it changes how most people live.

Who is paid. Carriers, builders and launch firms would pay, and since the trick could be copied once shown, the firms that already build vehicles and craft would collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Judged as the travel it allows: crossing between stars quickly would open new worlds to trade and settlement, an industry of its own, though most people's daily lives would change slowly.

Who is paid. Nobody can own a realm open to every ship, so shipping lines would pay for the ships that enter it, and established shipbuilders who could copy the drive collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A large prize. Personal flight without wings or fuel would be a new kind of everyday travel, though a narrower use than lifting freight and vehicles.

Who is paid. Ordinary people would buy it as they buy bicycles, and once one firm made it many could, so no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Lifting and pushing craft without burning fuel would cut the cost of flight and of reaching space.

Who is paid. Carriers and launch firms would buy it, and since others could copy the device once it is seen, the established builders of aircraft and spacecraft collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Lifting and pushing craft without burning fuel would cut the cost of flight and of reaching space.

Who is paid. Carriers and launch firms would buy it, and since others could copy the device once it is seen, the established builders of aircraft and spacecraft collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. Cancelling weight at will would cut the cost of lifting, carrying and launching, which changes transport and building more than it changes how most people live.

Who is paid. Carriers, builders and launch firms would pay, and since the trick could be copied once shown, the firms that already build vehicles and craft would collect.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

A large prize. A pocket device that frees its holder from gravity would give people personal flight, a new industry beside cars.

Who is paid. People would buy it for themselves, and with many makers able to copy a small gadget no seller keeps much.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

No prize. Cutting the planet loose from the Sun would kill everyone on it, so it is a hazard no one may use.

Who is paid. Nothing is sold, so nobody pays and no seller collects.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is not very sure of this one.

A small prize. A very large meeting hall is one building, a niche.

Who is paid. The government pays, and any large builder can put it up.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. A policy or worry about who may have children is a matter of rule and society, not something anyone would buy.

Who is paid. Nothing is sold, so nobody pays and no seller keeps anything.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.

No prize. Punishments for bad manners in crowded housing are law, not a product.

Who is paid. Nothing is sold, so nobody pays and no seller keeps anything.

A model's judgement, not a reading, of the idea as if it worked the way its story promises. The model is fairly sure of this one.