How do I make Tantalus' punishment real?

Question

Tantalus is a character from Greek mythology who did some bad things (trying to feed his son to the gods), and in turn was punished in Tartarus:

Tantalus (Ancient Greek: Τάνταλος, Tántalos) was a Greek mythological figure, most famous for his eternal punishment in Tartarus. He was made to stand in a pool of water beneath a fruit tree with low branches, with the fruit ever eluding his grasp, and the water always receding before he could take a drink.

The Greeks weren't too concerned with making the mechanics of this torture, because they had the god's magic powers to help them out.

A warden in the near-future (year 2,400) who has an ironic adoration of Greek mythology comes up with the scheme to punish prisoners who misbehave in a similar situation.

Our warden fellow needs to have 'water' that forms a depression when the prisoner bends down from his bindings to drink.

How could the warden create this effect with water?

Money is not an issue. The government spares no expense when it comes to making these prisoners have a hard time.

Answer 1

If the government spares no expense, then the easiest way to do this is through manual labor. Get maybe three people who can work 8 hours a day, just flipping a switch whenever the prisoner leans down for water. This switch opens three or four powerful drains that basically vacuum the water through underground pipes. When the prisoner is not leaning down, the employee flips another switch that propels water up through another set of underground pipes.

Either way though, within about three weeks, the prisoner will be dead without any access to water.

After rereading the question a few times, I think you're looking for a depression only where the prisoner leans down to drink, rather than lowering the entire water level. In that case, make the floor made of tiny pores with a diameter of 1 inch. These pores have the ability to suck water down and propel water up. Now, basically run a invisible laser grid over the surface of the water. Whenever any obstruction crosses this invisible field, the system should command the tiny pores directly underneath the obstruction to suck water down. By doing this, you've effectively created a depression whenever the prisoner leans down to drink water.

Answer 2

Instead of providing a design to raise or lower water level quickly in a controlled area, let me instead point out a fatal flaw in this method of punishment.

In Greek mythology the gods (obviously) had a knowledge of people's intentions before the people started to act upon them. This is not possible with human technology so far. We cannot calculate the intentions of people. We can only watch the action.

So if the water is at such a level that the prisoner's hands are inside water, he only need to cup his hands and take a small amount of water to drink.

OK, so we lower the water surface so that it only comes to the level of knees of the prisoner. Well, he can kick up with his feet and splash some water, a gulp of which he can catch with his hands to drink.

Just wanted you to be aware of these issues.

Answer 3

A simple mechanism tied to the prisoner will suffice. Set it up like so:

Wall          prisoner+pole      wall
 |               o_|               |
 |              \|/|---------------|--- water level up to here    
 <               | |               >
 |_____=====___ / \|_______________|

- the "==" represents a hatch or something that can "open"
- the ">" and "<" represents areas for water to pump in
-note the line beside the head/neck area - it represents a rope + collar
-Assume all limbs are bound and stationary so hands cannot be used to 
splash/cup water to mouth
-Assume body is tied to pole, such that only the neck + upper body 
can slightly lean forwards

Every time the prisoner leans forwards to take a drink, the neck will pull on the collar and in turn, the leash, which is attached to a pressure sensitive lever - the more the leve is pulled forwards, the more water drains from the hatch.

If the prisoner decides to lay flush to the pole that he's tied to, the pressure on the lever is relieved, so the hatch closes completely, and water pumps in back to the desired water level.

An alternative solution to this would be to put the prisoner on a platform that can raise/lower unnoticeable, giving the illusion that the water is draining, when really every time the prisoner leans forwards, his platform is raised up so that he can't reach the water.

Answer 4

Show him a holographic image with scent and sound.

Answer 5

Have a set of air jets just above the water level. And a facial scanner. When the prisoner's face approaches the water, the system aims and activates the jets such that they blow away the liquid under his face.

Of course, in many variation of the Tantalus myth, the entire pool lowers, not just a mystical depression in the water. Which could be done more easily and efficiently with just the facial scanner and a standard pump.

Answer 6

water is repelled by magnets. having sufficiently strong electromagnets in the ceiling that increase or decrease power based on the prisoners position would create a small depression in the pool of water. this wouldnt be great for nearby electronics, or really any metal objects, so you might have to put them in an x-men 2 style plastic prison. or just pump out the water i guess, if you want to be practical...