Tripoli, in another thread I asked Aussietaurus to define what he meant by a "working" hoverboard. As it's pertinent to the current, ridiculous discussion, here is the response:
a "working" hoverboard I would define as either repelling against the earth without a magnetic base to repel from, so nothing like this:
Crealev Levitation Rail with Hoverboard or I would define it as pushing against the earth using air pressure as hovercrafts do, one example is using air bearings. I realise the ground clearance is minuscule but it's a start
https://www.youtube.com/watch?v=bquSHvP5Gwc
So, here's my response:
The primary issue with a "working" hoverboard is power density and delivery. (Then stabilization and others)
There ARE hovercraft in the world but their ability to hover is based on having a large ducted fan attached to a HUGE powerplant. People who have attempted to make personal "hoverhoards" have consistently hit a wall when trying to get their devices smaller than about 2 surfboards wide and long. (And about a foot thick) That is because physical powerplants do now benefit from Moore's law. We are largely stuck with incremental boosts in power and efficiency over the years and the precision of the machines who make them are essentially approaching Zeno's Paradox as an upper limit to their precision. And with each microscopic improvement to machining tolerances, the efficiency and power remain statistically fixed with only minor improvements.
This applies to gas motors and electric motors equally. Electric motors also have the distinct disadvantage of also requiring batteries, which are not a very "power dense" storage medium. Compare the range of an electric car with 1,000 lbs of batteries in it (Approx. 40-80 miles) to that of a car with a 20 gallon gas tank. A 20 gallon gas tank holds around 120 lbs of fuel and will give you approximately 500-600 miles on a full tank. The power density of a liquid, burnable fuel is just vastly higher.
...but then the powerplant -- the motor -- is the issue. Electric motors are lighter and gasoline engines are MUCH heavier. You reach a point of diminishing returns with any motor/powerplant combo where you can't make things any smaller without having the device fail to have enough power to work, and you can't make things any larger or they'll be too heavy to lift. This goldilocks zone has been shown TIME AND TIME AGAIN to be about 8-12" thick and the length and width of about 2 surfboards side by side.
And if you're thinking this could work through some sort of magnetism without a powered, rigid track underneath, go grab some bar magnets and sit outside, see how many you can get to repell against the magnetic field of the earth. (Hint: You will get zero) You would probably need a few nuclear powerplants attached to the board to generate enough power to achieve any noticeable board movement through electromagnetism...and that's more likely to occur through an ionic wind-based mechanism which has almost zero lifting force and because of its reliance on wires, if you pump too much current into them, you WILL melt them.
So, 3 nuclear plants, some magical unburnable wire that can take gigaamps, composite materials that weigh less than aerogel, and a willingness to expose yourself to a magnetic field millions of times larger than an MRI as well as cast off radiation and you have yourself a working, city-sized hoverboard.
Are you getting it yet? It CAN NOT happen. It's not that we're being closed minded it's that your open mindedness isn't as open as you think it is. It's ignoring the evidence that would save you from spending time on this fruitless pursuit.
By all means, try to prove me (AKA all of science) wrong, but it's not going to happen. However, if you'd like to make a display stand to make a light, foam board hover, now that is doable...for a grand or two, but it will have to remain stationary.
-Nick
Let's keep moving.
