Sci-Fi Civilian Vehicles, Equipment and Technology

If they have wormholes and/or practical Alcubierre drives, then I would presume generating sufficient power is not a huge barrier for them.

I don't think so. Technological progress isn't deterministic and chance or external factors play an important role in determining which discoveries are made in which order. And a lot of discussions about realism - and not just in the context of fictional technology - tend to forget that. Example: In Real Life advanced AI and self-driving cars exist but jetpacks and flying cars don't. Or: We have medicine for COVID-19 but not for Alzheimer's disease.

Not quite. The Sun is still a disk in the sky from the distance of Pluto, just a tiny tiny one. It's not a point of light until you reach beyond the known dwarf planets like Haumea.

And while the daylight brightness on Pluto is greatly reduced in intensity compared to Earth, it's still far from being able to see the stars of the galaxy in broad daylight kind of dim.

It's not a Dark Planet kind of Single-Biome Planet, it's an Ice Planet kind.

So sci-fi cities and colonies. What would be the advantage to building a large underground city for a colony on a moon, even if you have terraforming technologies?

Cheaper? Quicker? More secret? More defensible?

The primary reason to build underground is protection from solar and cosmic radiation if the body in question does not have a suitable atmosphere and/or magnetic field.

That works. Terraforming can't exactly make a magnetosphere.

Well, it can, depending on how advanced you want to take the technology. You just have to heat up the core.

Take note, at least in the Solar System it seems like magnetic fields can sometimes actually destabilize atmospheres rather than the reverse...

I dont think i can express in words what an enormous leap of logistics the phrase "just heat up the core" entails. Terraforming an atmosphere is hard. heating up a core is magic.

And really, you could just build an artificial magnetic field at a strategic location in space (e.g. a lagrange point)

We're going to need nukes. Lots and lots of nukes.

But seriously, I've written off reheating the core of a planet like Mars off as Clarkian tech.

"I dont think i can express in words what an enormous leap of logistics the phrase "just heat up the core" entails."

Here is a fun idea.

Build A Flying Car. How would you go about making a flying car from Scifi work?

You need to establish the performance parameters. How about: a personal vehicle that is equally capable of moving through the air or on a prepared surface.

Step 1 for a flying car: invent antigravity. That's it, that's the process. There's no Missing Steps Plan, it's just "invent antigravity" and you can work almost any sci-fi magic you want.

More realistically, we already do have "flying cars", if by that you mean some of the crazy eVTVL prototypes we've seen in the past few years. Look up "the Jetson"; it's a battery-powered, fan-propelled car that looks like the one from The Jetsons.

There is a serious industry with multiple competitors that are all trying to be the first to make this technology commercially viable. Unfortunately, there are many reasons why it is not and can never be as efficient as a simple ground car, and it mostly comes down to physics.

First, the energy to hold a car up against gravity is given to us for free by the ground. If you don't have that, you have to put it in yourself, so any given amount of "fuel" will take you a shorter distance.

There's also the minor problem of crashes. In a car, if the motor stops working, you usually just pull over and have to call a tow truck. In the air, if the motor stops working, you are much more likely to be carried away by a coroner. There's no engineering that can completely solve this problem.

So, to make the flying car of sci-fi practical and efficient for everyday use to the point that it would replace ground cars, you need to solve that pesky gravity thing. Do that and you're golden.

Edited by Fighteer on Dec 9th 2021 at 9:40:01 AM

Well, "invent energy-cheap antigravity" more like...

Some kind of directional jets make the most sense to me

Frankly, i would say we already have flying cars, they're called helicopter.

Edited by devak on Dec 10th 2021 at 8:35:06 PM

We also have "flying cars" powered by jets; they are called VTOL aircraft. None of these are practical commuter options, though. Most concepts for such vehicles involve ducted fans powered by electric motors, essentially a consumer drone scaled up. They are notoriously difficult to control, requiring some form of computer assistance.

They also don't have much endurance due to the weight of their batteries. If we can solve solid-state batteries and make them cheaply enough, the consumer eVTVL market opens up.

There are problems that we cannot practically solve, however. The first is noise. If you've ever been around a helicopter or flown a drone, they aren't quiet. Making them so while also being efficient and cheap is probably impossible. If you start your morning commute by getting in your Jetson and deafening your neighbors (or blowing over their lawn furniture), that's going to get you sued in a big hurry.

The second is safety. Even with fully automated flight control systems, a mid-air collision or a failed motor is likely to be deadly. There's no practical way to make them survivable in a serious crash. If we look at the crash rate for ground cars and apply that to flying cars, even allowing for greater safety margins due to automation, we'd have hundreds of thousands of deaths in the US every year rather than a "mere" 40,000.

Lastly, there is the danger to things on the ground. Cars are restricted to roads, so that's where most crashes occur. Flying cars can go anywhere. Nobody wants their drunk neighbor or their neighbor's idiot teenager smashing through their roof at night.

Edited by Fighteer on Dec 10th 2021 at 2:53:29 PM

And what about the energy consumption? Clean energy has less environmental impacts than fossil fuels but it's not zero impacts and if the total energy consumption of society drastically increases, the cumulative environmental impact may become an issue. I am saying this because I get the impression that this risk is largely unresearched.

Yeah, it's definitely a concern, but we aren't introducing new energy into the system. 95+ percent (excluding some nuclear power) of the energy we use or will ever use on this planet comes directly or indirectly from the Sun, and it's got us covered for hundreds of millions of years. There are concerns about the albedo of solar farms having local climate effects, but nothing particularly serious.

The bigger concern is the environmental effects of manufacturing all those batteries and solar panels, which is why I agree that flying cars make no sense if it takes five times (or whatever) the energy of a ground vehicle to go somewhere in one. It's much the same argument that applies to hydrogen as a fuel source: at best it's three times less efficient than just putting batteries in your car.

Edited by Fighteer on Dec 10th 2021 at 3:36:05 PM

What if they were cars in name only? Like they're really magnetically levitated trains physically incapable of leaving their assigned lanes? The only difference between it and a trainline is that every car can switch rails independently. They'd still be flying cars but now they'd be flying train cars.

Edited by Belisaurius on Dec 10th 2021 at 5:29:11 AM

Magnetic fields fall off as the fourth power of the radius. You can’t do maglev efficiently at more than a few centimeters of height, which kind of takes the “flying” part away in any meaningful fashion.

Try to make the fields more powerful and people won’t appreciate their hard drives being erased and their tableware flying around the kitchen as you fly overhead.

Room-temperature superconductors would let us build maglev roadways but those are currently in the domain of science fiction.

Edited by Fighteer on Dec 10th 2021 at 6:00:47 AM

Going by current trends and expectations, what would be the closest "point" (well, more like a rough range of points) in the future where it would be plausible for a story set in that time period to have brain-computer interfaces mediated by injectable nanomachines that allow reliable fine control-by-thought of vehicles, robots and such, albeit with the interfaces being too expensive and/or demanding on maintenance requirements for the commercial market and thus in practice are for the time being reserved for wealthy private citizens, large organizations, governments, and those sponsored by any of the aforementioned?

Edited by MarqFJA on Dec 14th 2021 at 11:37:50 PM

Given the current state of the technology, 25 to 50 years? The challenge is the nanotech element, not the brain-computer interface.