If cheap and reliable anti-gravity devices (sufficient to allow personal flotation harnesses, flying cars, etc) were developed in the next ten years how would it change the design of cities and buildings?

Would we start seeing new and three-dimensional layouts or would people still be more comfortable with the conventional layouts?

Essentially we can now control gravity in the same way we control magnetic fields, for example we can place walkways up the side of buildings with gravity pointing towards them, we can have rooms with both the floor and the ceiling able to be walked on. Cars can float or fly, as can people.

The technology in question does require some power (so safety is a concern) but is reliable.

The larger the area and the larger the effect the more electricity it requires, but still personal flying devices would be affordable for your average person. Flying cars would maybe twice as expensive as a normal one, modifying gravity in buildings would be expensive and probably only used for the very rich or for commercial purposes.

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    $\begingroup$ Does it cost money to operate an antigravity device? If so, how much? $\endgroup$ Commented Apr 9, 2015 at 16:12
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    $\begingroup$ With all the bad drivers there are now, do you really want flying cars to be common? $\endgroup$
    – Frostfyre
    Commented Apr 9, 2015 at 16:14
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    $\begingroup$ What do you consider a 3D layout? Multilevel structures have been a thing for a while. Do you mean putting chairs on ceilings and doors halfway up the wall? $\endgroup$
    – Frostfyre
    Commented Apr 9, 2015 at 16:17
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    $\begingroup$ The first major change to a city would be the new building in Washington D.C. to house the Anti-Gravity Safety and Regulatory Agency. $\endgroup$ Commented Apr 9, 2015 at 21:32
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    $\begingroup$ Be very careful when musing about antigravity. It makes too easy to forget another physics principles. For example, if we put a man into a big box and then put box into antigravity, then first a man would hit a top of the box with his head and only then the box will ascend. Because man weights less than the box. Liquids in open containers would leave those too. Liquids in closed containers, including humans, will behave as if shaken once when entering antigravity. $\endgroup$ Commented Apr 10, 2015 at 10:16

10 Answers 10


Things would certainly be different in many ways, but in others they would stay much the same and I think that is a reflection of old versus new.

Building new infrastructure is one thing. New infrastructure is expensive to be sure, but it is far more expensive to update existing infrastructure.

Old Cities

Old cities can be broken down into (at least) two parts. Cities we consider old today, and the modern cities of today. When I speak of old cities today I mean places like Athens, Istanbul and the other truly ancient cities. These cities (at least the ancient portions) would likely change very little if at all. Which as a person who appreciates the old and its conservation is something I would whole heartedly agree with. Personal mobility would likely be the only significant change, having what amounts to a jetpack would make traversing the old cities much easier. Personal in home use (as you mentioned walking on ceilings) might change somewhat, perhaps allowing greater population density.

Modern era cities would likely change significantly more but it would take a long time for that change to be uniform. As I mentioned updating infrastructure is time and cost intensive. In a similar vein to white flight odds are the well off would move out of major "old" cities to live in new neighborhoods that were completely integrated with the new technology and then the technology would work its way back into the cities

New Cities

As mentioned in the old cities section these new modern cities would see the most rapid change and be the most uniformly impacted places. This is your city of the future where the infrastructure and construction were designed with the new technology in mind. This is the simple bit...relative to updating old cities.


The more commonplace this 3D environment becomes the more automation will be necessary. Managing navigation in a crowded 3D space may well be impossible for humans to manage with any reasonable level of safety. Either you can go the self-driving vehicles connected to a massive program to control them route or you can go with the 2D routes just elevated. So similar to two level roads you could do the same for flying vehicles creating 'lanes' above the street at a fraction of the cost compared to building and maintaining roads. I am picturing a sort of metal frame that the vehicles would have to stay within. This would be complex to design effectively...LOTS of on and off ramps.


Either route you go you are going to have a controlling agency akin to the FAA. This is particularly relevant in the automated flying cars scenario but I think would be necessary either way. You would likely have to make elevation restrictions based on classes of mobility. For vehicles, express lanes above 100 feet, between 50-100 feet for going to a specific local location, and under 50 feet would be for personal mobility vehicles...i.e. "jet-packs"


If you can get past the biological implications of being upside down...which is not a simple task you could drastically increase population density in city centers by allowing people to live on the ceiling. More practically and realistically it would make movement far more efficient making previously impossible routs available for transport.

All in all the changes would be drastic and the impacts to industry, transportation and personal life would be nearly as profound as say...electricity in homes in the 1900's it would simply change the way humans live and interact with the world on a very fundamental level.


You make mention of anti-gravity, but also talk about walkways on the sides of buildings. More than just anti-gravity (reducing the effects of gravity), this implies that your futuretech is actually directional gravity manipulation.

Anti-gravity alone would have a great effect on construction. Buildings of far taller sizes could be manufactured with greater ease - you would not need nearly as powerful cranes to lift building materials. If the anti-gravity technology can be built into the structure itself, you could potentially use lighter materials because the load of the whole building could be reduced. Either way, the end result is verticality - buildings would be very, very tall. (The manufacturing implications of gravity control technology is touched on, albeit briefly as it is not the focus of the story, in David Weber's Honorverse.)

Assuming the cost was cheap enough, anti-gravity would also drastically improve the capability of humans getting into orbit. As an alternative to tall terrestrial structures, you'd have the capability of building large structures in space. If the technology is truly directional gravity manipulation, you could provide those structures with internal artificial gravity, eliminating the micro-gravity related problems of long term space habitation. Anti-gravity without directional gravity manipulation would still reduce resupply concerns, making living in orbit more attractive.

Despite easing the engineering implications, I think the larger concern is the human factor. The human body uses a combination of what is effectively a gyroscope in the inner ear and visual stimulus to determine where you are and where you're going. Without really having directional gravity manipulation, there's no way for us to test it, but I suspect there would be issue with your proposed walkways - the ear, subject to gravity would be telling the brain one thing (down is towards my feet) while the eyes would be saying something different based on the horizon. In a space habitat, the horizon/orientation problem is mitigated because the environment is presumably small enough that your senses tell you you're inside at all times.


Buildings would get taller and/or leave the planet completely, but the orientation would remain the same.

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    $\begingroup$ While the use of artificial gravity during construction is a good point, I'm dubious about using it to help support the buildings afterwards. Presumably you'd have some kind of battery backup, but if an extended power cut exhausted the supply, you'd be in big trouble. $\endgroup$ Commented Apr 9, 2015 at 21:59
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    $\begingroup$ @HarryJohnston In fact a similar event happens in Larry Niven's Ringworld, in which an extended and complete loss of power causes all of a world's flying cities to crash to the ground. One of the characters hypothesizes that the inhabitants valued the convenience of denser cities more than they feared the (supposedly tiny) chance of total failure. $\endgroup$ Commented Apr 10, 2015 at 0:27
  • $\begingroup$ @ChrisHayes: Christopher Stasheff's Warlock series (don't recall which book) referenced a similar event, though on a smaller scale. In that case the architect was using anti-gravity for aesthetic reasons rather than for any practical purpose. :-) $\endgroup$ Commented Apr 10, 2015 at 0:31
  • $\begingroup$ Looking at the Honorverse novels we also have the Stephanie Harrington books--while it's not actually addressed I get the definite impression that they can drop loads into the wilderness without the need for clear space--a task that while possible for helicopters would be hard given the forest on Sphinx. No sparsely populated planet at our tech level could support things like the Harrington homestead. $\endgroup$ Commented Apr 10, 2015 at 3:26
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    $\begingroup$ @HarryJohnston I wouldn't want to live in a structure that required power to maintain integrity, but that doesn't make it any less plausible given the technology in the first place. $\endgroup$
    – T.J.L.
    Commented Apr 10, 2015 at 12:15

As with many situations, it depends.

You've specified that these devices are sufficient to allow personal flotation harnesses, floating cars, etc. However, it follows logically that the more of them you have, the more mass you can lift.

So, as alluded to in the comments, the major factor here is cost:

  • How much does it cost to manufacture one?
  • How much (if anything) does it cost to maintain one?
    This includes energy costs, repair and upgrade costs.

If these devices can be manufactured and run cheaply, they will quickly become fairly standard in building and vehicle design. The use of the air allows much more space for driving around in - just make sure you limit altitude so people can't crash into planes. That said, flying cars might even make the aerospace industry fairly obsolete.

The speed of integration of these devices will vary fairly linearly with their costs: high costs = slow integration; low costs = fast integration. It also depends, as the comments say, on area of effect: a large area of effect means you need fewer devices to cover a bigger area, thus reducing total cost and speeding up integration.

However, society, as always, plays a big role in the speed of acceptance of these devices. As with any technological revolution, there are naysayers and yaysayers, and while I don't want to rigidly stereotype, the acceptance is often affected by age. The older generation are more likely to cling to what they've always known; the younger, more inquisitive generation are more likely to want to try this out as soon as possible. You can see examples of this in many new technologies: in my personal experience, I adapt to new technologies and developments quickly, while my parents and older family are happy with how things are.

  • $\begingroup$ I can just imagine the debates over antigravity drones... $\endgroup$ Commented Apr 9, 2015 at 16:52
  • $\begingroup$ @DaaaahWhoosh That... is a bad thought. Even worse than normal drones. $\endgroup$
    – ArtOfCode
    Commented Apr 9, 2015 at 16:53
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    $\begingroup$ There's also the issue of safety. In order for any new technology to be approved for public use, one always has to answer the question of "what happens if it fails?". If the engine on a car dies, you pull over and slow down safely. What happens if your anti-grav car shuts off? What about your vertical walkway on the side of the building? If there aren't fail-safes, there's no way anti-grav would be approved for public use. $\endgroup$
    – David K
    Commented Apr 9, 2015 at 19:06
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    $\begingroup$ @DavidK you could write that up into an answer $\endgroup$
    – ArtOfCode
    Commented Apr 9, 2015 at 19:08
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    $\begingroup$ "it follows logically that the more of them you have, the more mass you can lift", not necessarily, there can be interference or other effects. Actually most things we have scale up well only up to a point, and then there starts to be complications (like adding more rocket engines to a rocket or making single engine bigger, there's quickly a point where things start to go boom a bit too often). $\endgroup$
    – hyde
    Commented Apr 9, 2015 at 19:39

I've read this in some Stanisław Lem book ("Return from the stars", I think), so it is not my idea, but I liked it a lot:

The antigravity device should be able to dampen any acceleration, not only the gravity. So, you would have a cheap and reliable safety device: in case of any crash the device just nullifies the acceleration, so no damage is taken at all. You could equip the cars and other potentially dangerous objects with this device. You could give this device to people and make it work automatically when, for example, the person fails.

I guess, people would be still very cautions at the beginning, but this level of security is quite promising, and, I guess, the technology would be accepted quickly. As the devices would become common, the fear of height or crash would reduce, so, I suppose, 3-d layout would be only a matter of time.

  • $\begingroup$ An antigravity device could make it so you would walk away from a car vs obstacle accident but car vs car would still be a problem unless both cars were so equipped and neither car had things which could come flying off. $\endgroup$ Commented Apr 10, 2015 at 3:20

Having freely-available antigravity would turn the concept of security on its ear. Fences, walls, gates, moats or trenches, and any and all access control devices that restrict movement in two dimensions instantly become obsolete when the average intruder is able to simply fly over them.

There are two ways to deal with this, as an author. Develop an entirely new physical access control paradigm, or have someone come up with an anti-antigravity technology that they install on security walls, fences, etc, that projects a field upwards that disrupts antigravity. This, of course, would lead to an arms race between intruders and security people. Maybe parasails or hang gliders become standard equipment for the determined thief, to allow them to glide safely over an anti-antigrav zone, for example...


TL;DR - Probably not a lot

Probably the biggest driver of approving new technology for public use is safety. This always involves the question of "What happens if said technology fails?". If the engine on a car dies, you pull over and slow down safely, but what happens if your anti-grav car shuts off? Will everyone have ejector seats and parachutes (not that that would even work well)? What about your vertical walkway on the side of the building? If your anti-grav fails, what will happen to the people standing on the side of the 10th floor?

Whatever new technology is incorporated into the public landscape, there needs to be fail-safes for everything. I personally have a hard time coming up with a reasonable way to keep people safe when your anti-gravity systems fail. Unless you can come up with some strong backup systems, there's no way anti-grav would ever be approved for public use, and so your cities of the future would probably look pretty similar to those of today.


...personal flying devices would be affordable for your average person.

I think that alone would change a lot. Most people would own and always wear a personal flying device. Flight controls and safety measures on these devices would become very advanced, as would auto-pilot systems. People would simply fly to anyplace nearby (work, school, etc.), rather than use a vehicle. This would lead to some interesting clothing (bubbles?) with an emphasis on aerodynamics and warmth.

Flying cars would maybe twice as expensive as a normal one...

I think what you would have is independent gravity-control devices that could be attached to anything. No need to have a car at all -- people would simply fly with their personal flying device, and put their possessions/luggage in separate container that has it's own flying device, likely set on auto-pilot.

...modifying gravity in buildings would be expensive and probably only used for the very rich or for commercial purposes.

Due to millions of years of evolution I think people will still be most comfortable with a basic gravity-goes-down setup. Besides if people all have personal grav devices, there's not much of a need for a gravity controls inside the building itself (kind of like how there are fewer public pay-phones now that most people have cell phones on them at all times). I think there would be some floating buildings though -- although, given the expense, they might be limited to big businesses, novelty clubs/restaurants, and security buildings.

I agree with TJL: "Buildings would get taller and/or leave the planet completely, but the orientation would remain the same."

Since everyone will be able to fly, this question may be helpful too: How would an avian city be different from ours?


Why We Don't Have Flying Cars.

It's not about technology. It's that most people can barely drive in 2D. Forget 3D. That's why few people get airman's licenses. All kinds of buffering fail in a big enough accident, and pieces rain out of the sky.

Skirts are gone, over. You never know what direction your feet are going to be pointing, so trousers, long or short, will be part of public decency. They might remain as fetish wear at home or in places of amusement.

So new architecture won't worry about making stair treads opaque. In fact, I imagine stairs will be emergency wells only: you step into the lift and float up or down.

I really like the suggestion that as soon as we have personal lift belts, the whole business with passenger vehicles will be over. Freight can be delivered by underground trains and trucks, and never appear on the streets. People in their bodies are much less dangerous than drivers in vehicles. A bubble of antigrav can keep off precipitation and most collisions, I imagine. I think this also does away with fear of heights and fear of falling, as one always wears one's belt.

Security is a concern, yeah. It can no longer be just at ground level, but will have to be all the way up an exterior, including the roof.

Still, I think flipping directions will mainly be a novelty. It's physically unsettling. It's like glass outside elevator shafts. How many buildings bother?

The trick is to imagine in what industries this would be useful. Business rent will be charged by cubic feet, not square feet, because you can put more cubicles on the ceiling and walls, and float the lights between. Warehousing becomes much easier, as does work in shipyards.


Let's assume that traffic control for flying cars and trucks can be solved. GPS, computers, good training and licensing, whatever. Also assume that they can fly at the speed of a small aircraft, not the speed of a ground car.

  • Express highways could be replaced by designated air lanes at high altitude. They're both cheaper than ground highways and higher capacity due to vertical stacking, and faster because they don't mix with low-altitude traffic.
  • The same would happen to major streets in the city on a slightly lower/slower scale. Instead of multiple lanes arranged horizonzally, there could be multiple lanes arranged vertically. No need to worry about a toddler running onto the road if that road is 20 feet in the air.
  • There is still a requirement for parking space. Either on a reinforced roof or in front of the houses.

That could replace all/most city streets with relatively narrow lanes for pedestrians and bicyclists, lined by parking space. Green grass instead of hardtop roads?

The increased speed could also allow longer commutes, allowing suburbs to spread out more. The poor can live more in densely packed inner cities, the rich can live on larger estates?


I would imagine that if you could cast the effects of an anti-gravity device over a large area city design would probably reflect what a space habitat would look like at least in a minimalists form. A spce city would look like this:

enter image description here

I would imagine people living in artificial houses resembling this on a much smaller scale. After all, we still need gravity, right? The spin of the house would create artificial gravity and might be auto piloted by a computer to prevent it from exiting the zero-g zone.

These zero-g communities would only be available as vacation homes to the ultra rich due to the cost of designing and building a house regulated by a primitive AI and the fuel needed for the thrusters that would be used to keep houses in the zero-g zone.

If you want flying cars, I suggest not applying the zero-g field to a wide area, but rather creating a narrow strip of zero-g generated above a certain point. Therefore there are very clear "sky-lanes" and people on the ground can still choose to use ground-based vehicles.

I guess the most noticeable way this might effect city design would be the power grid in zero-g area would be better built, better secured, and they might have many fallbacks. If the main grid gets knocked out they would have many more backup generators so that floating houses and flying cars would not.....learn the effects of gravity first-hand if the main grid gets knocked out.

As a side note, car design might be effected. If the anti-g drives are as cheap as you imply in your comments and edit, then what is to stop people from putting them in cars? The problem there is that traffic would be less regulated than if using the sky-lane idea. This might only be legal for law enforcement, in that case.


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