# I'm getting impatient for my flying car. It's been promised to me as early as the '50s.April 15, 2010 11:36 AM   Subscribe

(via Wired about flying cars & Darpa). Explain to me like you would to a twelve year old how far we are with the concept of anti-gravity (Heim theory etc.) Is it theoretically possible? How would it work? When can I order my flying car?

Every time I'm stuck in traffic, I think: how much easier would traffic be if we could just lift cars as little as 3 to 10 meters off the ground. No more crossroads with stupid lights that block you from using the crossroads half the time (or even more).

Then again, this idea of autocopters - basically fitting cars (and their drunk drivers) with big chunks of metal that spin around at a few 1000 RPM is not particularly appealing. Think of the noise, the energy required. Think of the price of driving/flying lessons! So: antigravity. When? How?
posted by NekulturnY to Travel & Transportation (12 answers total) 2 users marked this as a favorite

You're underestimating the amount of energy required to lift a ton or more of metal and plastic into their air relative to the size of the engines cars house.
posted by dfriedman at 11:41 AM on April 15, 2010

When you look at all of the other three fundamental forces (let's not unify them just yet), you wonder why gravity matters. The electromagnetic force is roughly 1040 times more powerful than gravity. The strong and weak nuclear forces are less powerful, but they're still fairly amazing. Of course, those two are short-range forces, dropping off relatively quickly. EM drops off like 1/r2, just like gravity. However, with EM, you have positive and negative charges and things tend to mix together, then cancel out as you step back. Not so with gravity. It always attracts. Oh, people postulate some exotic matter with negative mass, not antimatter, but negative mass. Nobody has seen it or has any idea how to make it. Gravity relentlessly attracts, never canceling out, reaching over distances for which the strong nuclear force cannot hope. Despite looking like the weakest contender, it wins, sculpting structure over millions of light years where other forces cannot.

Gravity rules you.

Einstein's big idea for general relativity, from which all related theory descends, is a fundamental unity (the equivalence principle) between gravitation and inertia, between mass in the context of gravitational attraction of an object and mass in the context of being able to alter the relative velocity (or lack thereof) of that same object. Knowing that, any antigravity technology will probably have to deal quite a bit with inertia itself, that resistance to shoving a bowling ball into motion relative to you. One might wonder if an object without gravity would also be an object without inertia at all.

I would not want to be in a vehicle with no inertia.

Of course, one may hope that you could somehow separate the two, keep the inertia, lose the gravity. I think how will tell you when. Given my feelings about How, my When is "never."
posted by adipocere at 12:00 PM on April 15, 2010 [3 favorites]

That's not very much energy at all - a few mL of gasoline could do it.

The problem is that antigravity, in the form the OP is talking about (not in the form of, say, a chair), is as unlikely to be developed as anything you can imagine. You ask how far we are with the concept? Pretty far. Scientific consensus is that it's not going to happen and that "Heim theory" is wrong or unintelligible.
posted by Mapes at 12:01 PM on April 15, 2010

Every time I'm stuck in traffic, I think: how much easier would traffic be if we could just lift cars as little as 3 to 10 meters off the ground.

It would not be easier. Every auto accident would involve the high probability of adding a fatal fall from the sky to the actual car impact. Think about all the people out there who are not terribly good drivers. Now add up and down to the directions that they have to keep track of when controlling their car. Do you think that would end well? How will they see what is below them? There will never be flying cars, because it's a terrible idea.
posted by The World Famous at 12:01 PM on April 15, 2010 [2 favorites]

@The World Famous. I would reckon that any flying car would not be piloted by humans but by computers. If we could solve gravity, surely we can take human driving out of the equation. I would be strongly in favour of doing that long before we start antigravity cars...
posted by NekulturnY at 12:09 PM on April 15, 2010

I am not a physicist but my tenuous, layman's grasp of QM suggests we're closer to finding the key to mass teleportation than levitation. Which would render moot the whole point of flying cars. Of course, we're pretty far away from that particular breakthrough too.
posted by The Winsome Parker Lewis at 12:13 PM on April 15, 2010

I would reckon that any flying car would not be piloted by humans but by computers.

At that point, what's the advantage of flying cars over, say, busses and trains? Or multi-tiered roads with on and off ramps and merging instead of traffic lights? And what about system failures and their effects? There's no good reason to have cars fly. Sure, having just one person's car fly would be advantageous to that one person. But having everybody's car fly would just move traffic up and increase danger.

Have you ever been somewhere that was supposed to have a cue of people waiting for something, but people just didn't wait in the cue, instead just bunching up in a big crowd? With flying cars, either you can have everybody get in a big cue, just like with current traffic, or everybody can try to skip the cue, making a giant crowd of cars in the sky that would not make anything better. Computer-controlled traffic could solve a lot of congestion issues. But it wouldn't be any better to do that 30 feet in the air than it would be to just do it on the ground.

But getting back to your original question, you would see computer-controlled commercial air traffic decades before computer-controlled road traffic, and computer-controlled road traffic (which would be a fundamental change to the entire infrastructure of the civilized world) many decades before anyone decided it was worth it to try to convert the entire transportation infrastructure of the civilized world - again - to a totally new mode of transportation that introduces unnecessary extreme danger to the equation.

Basically, even if we were anywhere near being able to make a car fly through anti-gravity or something other than what already makes things like airplanes and helicopters fly, there are such massive infrastructure and practicality barriers in the way of what would make flying cars make any kind of sense that the technology would never be implemented in making everyone's car fly anyway.

When you sit in your car in traffic, you imagine how much better it would be if you could just fly over the traffic. You don't imagine how much better it would be if the government first took away everyone's ability to steer and control their car and then decided to make those cars that nobody is driving fly up in the air in a neat row. Because if you really sincerely believed that, you'd probably be on a train or a bus. Sure, the cars in Minority Report look cool, with the passengers sitting in them passively and riding along as the cars merge with each other and travel peacefully to their destination. But even that imaginary system - which would require rebuilding the entire transportation infrastructure of the civilized world - didn't need the cars to fly. There's just no point in putting the cars up in the air.

Think about it: Would there be any point in flying in a commercial airliner if the plane didn't go any faster or cost less than a train?
posted by The World Famous at 12:23 PM on April 15, 2010

You can get on the waiting list for one here.
posted by snowjoe at 12:40 PM on April 15, 2010

Hm, The World Famous, even with computer controlled traffic, I can see huge benefits to flying cars (you're quite the buzzkiller, btw!). Seriously: a road or crossroads, no matter how intelligently designed and managed, can only take so much traffic in a given amount of time and will congest when millions of people leave the office in the evening (cities are expected to grow even more dense in the next century).

With the possibility of stacking traffic - even in neat rows - in 5, 10 or more layers, there would be considerable benefits. On top of that, you could probably give the streets back to pedestrians; and you probably wouldn't need to maintain asphalt roads, which cost millions in repairs (and resources).
posted by NekulturnY at 1:26 PM on April 15, 2010

Those are good points, NekulturnY. Figuring out what effect bottlenecks at destinations and other such variables would have and whether the expenditures necessary to implement the system would be more efficient than other, lower-tech solutions would be a difficult calculation, I think. But it's conceivable that there might be some way to make flying cars a viable system in some future infrastructure. I do think it's extraordinarily far off, at the very least, though, and would depend on a lot more than just having the ability to put the cars in the air.
posted by The World Famous at 1:33 PM on April 15, 2010

NekulturnY, I've read (unfortunately I don't have a source in front of me at the moment) that traffic jams are actually created much more by variation than by volume. I could easily imagine a computer-controlled system that was observing both the individual car and the entire network and controlling the pacing, spacing and direction of each car such that it could balance out loads and significantly improve even the most snarled traffic.
posted by Slothrop at 1:47 PM on April 15, 2010 [1 favorite]

Although I agree with The World Famous about the impracticality of flying cars as a mainstream transportation system (I think even computer controlled traffic would result in tons of fatalities and property damage when something fails), the sort of levitation technology you're talking about would undoubtedly have tons and tons of extremely useful applications.

Unfortunately, I think we're so far off from having anything like that, we wouldn't even know where to start. Like, as close as a Chimpanzee is to creating a sentient AI. According to our current understanding of physics, there's just no way. It's possible we'll never learn how to create "anti-gravity". It's possible that it just can't be done.

However, I Am Not A Physicist.
posted by Vorteks at 1:12 PM on April 16, 2010

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