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I have an idea for a location in my world that I would like explained by natural phenomena rather than magic if at all possible.

I would like to have a temple...that floats.

The specifics:

  • The temple (and the ground it rests on) floats at least 18 inches (46 centimeters) and no more than 5 feet (1.5 meters) off the ground.
  • The temple should be approximately 20 feet wide (6 meters) and 40 feet deep (12 meters) and the ceiling should be at least 10 feet up (3 meters)
  • The 'land' it sits on may be sized to accommodate the scenario
  • The temple should be made of some kind of stone, less dense stone makes more sense I suppose
  • The temple and its platform/land will be chained down to the earth so it doesn't fly away.
  • A large enough gathering, say 40 - 50 people (average weight 170 lbs/77 kg) should cause it to touch the ground
  • The floating effect should not be maintained by magic. If there is no plausible way to create it in the first place, magic can be used to set things up.

Questions:

  1. What could cause this temple and its land to float? This does not have to be 'hard-science' but should be scientifically plausible even if it is in no way likely to happen.

  2. How much force would it take to keep the temple and its land afloat? (use whatever materials make sense within the parameters of the scenario) I would like calculations for this portion of the answer.

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    $\begingroup$ Can you please amend your post with metric equivalents to the values, so that also non-Americans can understand them? $\endgroup$ – celtschk Oct 14 '15 at 19:59
  • $\begingroup$ @celtschk um...maybe...let me find a site that does metric conversions quick... $\endgroup$ – James Oct 15 '15 at 13:35
  • $\begingroup$ Man it has been a really long time since I have dealt with metric... $\endgroup$ – James Oct 15 '15 at 14:36
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Building on @oxide7's answer regarding magnetism, you might consider quantum locking. Quantum locking is a hard-science phenomenon in which a superconducting material can be "locked" in place in a magnetic field, even against a gravitational force. Search for quantum locking on YouTube for some really neat videos of the phenomenon. Of course, there are some drawbacks.

  • All known superconductors only have superconducting properties at very low temperatures (the highest common one, I think, operates at 70 Kelvin). But there is no reason there could not exist some strange material we have not yet discovered that has superconducting properties at room temperature.
  • Quantum locking fails when we apply enough force. To support more force we need more superconductor and a bigger magnet. You would need a lot of superconductor and a very strong magnetic field to support a stone building. This would get very, very expensive. But again, I think you could work around that too. The superconductor could have been discovered at the temple site (naturally occurring), and there could be a iron rich magma pocket-turned-dynamo in the mountain which uses some fancy magnetohydrodynamics to generate a strong natural magnetic field at the top of the mountain. Note also hat the superconductor works best when formed in a very thin sheet.

With a few conservative additions to current science, I think that quantum locking does what you want.

For the next part, assume that your temple is $40\times20\times 10$ feet with $1$ foot think walls and ceiling. This comes to 1834 cubic feet, or 51.93 cubic meters. Assuming that you may want a spire, columns, or some other type of decorative stonework, and ground for it to sit on, I will almost double this to 100 cubic meters. At a density of 2600 kilograms per cubic meter of granite, we get 260,000 kilograms of granite. Multiplying by gravitational acceleration, we arrive at about 2.5 million newtons of force. To put this in perspective, this is about one fourteenth the force provided by the principle stage of a Saturn V rocket.

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Turn the Hindenburg on its end and put it in the attic. Shape the outside of the attic in some visually impressive way, like maybe a church steeple. Hang the gathering place underneath. For the walls, hang thin stone cladding onto an aluminum skeleton.

Oh, the divinity.

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    $\begingroup$ I forgot to mention the most important part: no smoking. $\endgroup$ – Doug Warren Oct 14 '15 at 17:19
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    $\begingroup$ So no incense burners then...got it $\endgroup$ – James Oct 14 '15 at 18:01
  • $\begingroup$ I'm afraid you'd have to still tether it to the ground. Is that allowed? $\endgroup$ – Mikey Oct 14 '15 at 18:51
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    $\begingroup$ @Mikey, it's not just allowed, it's required. $\endgroup$ – Doug Warren Oct 14 '15 at 18:53
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    $\begingroup$ @Mikey That's what I meant too. The fifth item in his requirements list is: "The temple and its platform/land will be chained down to the earth so it doesn't fly away". $\endgroup$ – Doug Warren Oct 14 '15 at 19:06
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The temple could be the terminus of a space elevator. These don't need to be anchored to the ground: their centre of gravity is in a geosynchronous orbit and the cable is basically just hanging down from that. The cable stretching up from the temple roof and disappearing into the heavens might be seen as proof of the temple's divine greatness. An actual elevator car coming up and down the cable from the temple would probably add to this, and citizens who had been generous at collection plate time could maybe get a ride in it.

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    $\begingroup$ While the counterweight in space would certainly keep it from falling to the ground, I don't see how you would prevent it from having significant horizontal movements without anchoring it to the ground. After all, it's a really big pendulum, and there are certainly more than enough forces acting on it (wind forces, tidal forces of sun and moon, Coriolis forces from the elevator car going up and down, and probably others I didn't think of). $\endgroup$ – celtschk Oct 15 '15 at 18:10
  • $\begingroup$ @celtschk yeah, i did think about that when i wrote it, and then decided to not bother worrying about it any more. I think you're right in that there would be significant, and perhaps insurmountable, practical problems associated with having a temple tied to millions (maybe) of tons of metal/carbon/etc whose centre of gravity was in orbit 22,000 miles away. But, you know, if this isn't hard science they might get away with it. $\endgroup$ – Max Williams Oct 16 '15 at 12:07
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You could have the land and the temple be built out of some magnetic material that doesn't weight too much.

The magnetic field of the world could be out of whack from an oddly spinning core, or binary cores or anything strange like that. This temple probably wouldn't be the only odd phenomena tho. The ground the temple hovers over could simply be pole reversed magnetic material also. Electromagnets could be a thing too, but this would be deliberate.

You could have the temple be levitated by heat trapped underneath a specifically shaped land under the temple. The temple could be above some fault with heat vents.

The temple could be made of a material that is very light, and strong and also somehow infused with lighter than air particles like hydrogen or helium.

The temple could be in certain area with massive updrafts and the temple was built to specifically take advantage of this and remain "neutrally buoyant".

Or the temple is simply built with such perfect craftsmanship that the normal wind in the area (it's a bit windy to maintain the effect) that the temple levitates because of it.

I have more idea if none of these are any good. With magic I can give you another dozen at least.

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  • $\begingroup$ I also agree with using magnets of some kind $\endgroup$ – Nonafel Oct 14 '15 at 17:07
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Soft Rock, Shelter & Bugs

Centuries earlier, your natives found an interesting, porous material (like limestone but way more porous) that was extremely rare, so they used it to build a temple and clad it with decor. The interesting thing about this rare material is that there is a rare bug like a non-damaging termite that loves to inhabit it, and only it.

The bug has a unique characteristic. As it ages, and it consumes energy or other bugs, it has a bladder that expands with a lighter-than-air gas. As the colony grew, the temple began to lift.

This was an amazing miracle. Over the years, when the colony of bugs got "full" in the all of the building material, the temple had lifted about a meter in the air! It lowers ~ 1m depending on the number of worshipers in it, finally touching the ground at about 40 to 50 people.

Luckily, this ancient temple had dense trees that grew around it as it gradually lifted over time. The tree branches help gently keep the temple from drifting away and help protect it against high winds.

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  • $\begingroup$ I think doing some small calculations would show that the volume of flying insects, even at the minimum possible density (0, which is impossible due to the required mass required to contain a vacuum), would be too high to be practical. $\endgroup$ – rytan451 Jun 21 '17 at 5:58
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OK, first let's estimate how much force you'd need.

Let's start with the mass. The temple should be made of stone, you say. The lightest stone as far as I know is Pumice. The stone in the image on the Wikipedia page has, according to the caption, a density of $0.25~\mathrm{g}/\mathrm{cm}^3$. Since I can't fine a more general statement about the density (apart from "it floats on water") I'll assume that this is a typical density, and use it in the following calculations.

Unfortunately I cannot find much about the other properties, so I can only guess on how thick the walls would have to be. I'll assume 25 cm, which is a normal thickness for an outer wall. I have no idea what a normal thickness for the roof would be, so I'll assume the same there; the floor plate (the "land") should probably be twice as thick to carry the load. But note that this is just a guess. I'll just calculate with a flat roof, although the temple will probably have a non-flat roof.

So putting all the numbers in, I get:

  • 1 roof: $600~\mathrm{cm}\times 1200\mathrm{cm}\times 25\mathrm{cm}\times 0.25 \mathrm{g}/\mathrm{cm}^3 = 4500~\rm kg$
  • 2 long walls, each half as high as the roof is wide: $4500~\rm kg$
  • 2 short walls, each half as long as the long walls: $2250~\rm kg$
  • 1 floor: twice as thick as the roof, $9000~\rm kg$
  • 50 people, $77~\rm kg$ each: $38500 kg$
  • You'll probably also want to put some stuff into the temple; let's add another $900~\rm kg$ for it.

So the total mass of the temple including people is about $25000~\rm kg$. Assuming earth-like gravitation (i.e. $g=9.81~\mathrm m/\mathrm s^2$), this gives a force of about $245~\rm kN$; let's round it up to $250~\rm kN$ for easier calculation (that then allows also for a more fancy roof).

Now the density of air is $1.225~\mathrm{kg}/{m}^3$, so the lower bound of the volume you'd need to get enough buoyancy (namely, if you could just use pressured vacuum, which of course doesn't exist) would be about $204\,000~\mathrm m^3$. For comparison, your temple itself has a volume of $216~\mathrm m^3$. So you'd need about 244 times the volume of your temple to create enough buoyancy (in reality more since even the lightest gas is considerably heavier than the imaginary pressured vacuum, and thus provides less buoyancy).

So unless you could live with a gigantic balloon on top of your temple, buoyancy is out of the question, even if you manage to get the mass down to a tenth of what I calculated.

So what else could we use to create the gigantic force? Well the strongest force in the universe is the electromagnetic one. So let's see if we can do with that.

The first idea would be that the floor and the temple contain electric charges, so they repell each other. You'd need to perfectly insulate both charges (especially the one in the floor) so they don't simply flow away. Now, how much charge would you need?

Let's for simplicity assume that the charges of the temple and the floor are both contained in giant plates, one in the floor below the temple, and one in the floor of the temple. Let's als assume that the charges are of the same magnitude. The formula for the force is then $F = Q^2/(2 A\epsilon_0)$ where $Q$ is the charge, $A$ is the area of the plate, and $\epsilon_0 = 8.85\cdot 10^{-12}~\rm As/(Vm) = 8.85\cdot 10^{-12}~\rm C^2/(Nm^2)$. Solving for the charge gives $Q = \sqrt{2 A \epsilon_0 F}$, and inserting $A = 6~\mathrm m\times 12~\mathrm m = 72~\mathrm m^2$ and $F=250~\rm kN$, we get $Q = 0.017~\rm C$. Now that doesn't sound much, but when you calculate the field strength that results, you find that it is $14.7~\rm mV/m$, which is almost five times the breakdown field strength of air (that is, the voltage at which you get lightning/electric arcs). So again, that's not a good solution (I certainly wouldn't enter that temple!)

So what remains is magnetic forces. Unfortunately I don't know how to assess if this would give a reasonable force without unreasonable assumptions.

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Magnetic levitation requires no power and can lift a large amount of weight if you use enough magnets or strong enough magnets. The problem with static magnetic fields is that it is unstable, the building will try and spin around so north and south poles from the base and building are next to each other and then drop.

The chain on the building though would actually be to stop it spinning, not to stop it flying into the air. It would work rather like toys such as this one:

enter image description here

In this case the plate at the end and shape of the spindle stop it from spinning around or moving sideways. The same could be achieved with a chain though.

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  • The temple rests on a single flat stone as a baseplate.
  • Under the baseplate there is a shaft into the ground.
  • A complicated tunnel system ensures that there will always/most of the time/often be a strong wind out of the shaft. This wind is strong enough to lift the stone with the temple, but not strong enough to lift the visitors as well.

The likelihood of finding a natural place like that is slim. Magic might reshape the landscape and shape the stone foundation. Getting onto the slab will be tricky, considering the wind speed all around.

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    $\begingroup$ I think you're going to need a wind with a force comparable to that coming out the bottom of a rocket. The force of this would fly out from underneath the bottom of the temple, to the sides, like a mega-hurricane. $\endgroup$ – Max Williams Oct 14 '15 at 16:34
  • $\begingroup$ @MaxWilliams, I would compare it to a large hovercraft. Less power, but not much less. $\endgroup$ – o.m. Oct 14 '15 at 17:56
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    $\begingroup$ Hovercrafts also float using insanely strong fans which produce blasts similar to that of jet engines. You won't want to stand behind either. An alternative is to imagine the downdraft of a helicopter, then increase the helicopter's size a thousandfold. $\endgroup$ – March Ho Oct 15 '15 at 8:34

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