3 ms·
No comments or ideas, but a question triggered by watching this video: Two prisoners in soundproof cells are communicating through a shared underground puddle
by sfink 3y ago
No comments or ideas, but a question triggered by watching this video:
Two prisoners in soundproof cells are communicating through a shared underground puddle that has a small opening in each prisoner's cell. They communicate with Morse code, by repeatedly poking a stick into the opening that fully fills it. Water being incompressible, it causes the water level on the other side to rise slightly.
Please ignore the fact that sound travels quite well through water. Perhaps the prisoners are deaf.
The question is, what is the maximum bandwidth of this communication channel? Ignore any physical limitations on the prisoner's part with respect to the speed of poking their sticks in, and assume they both have a great sense of timing and can only either poke or not poke; they cannot do small vs large pokes.
Let's say the little underground water tunnel is exactly 1 meter in length, and the perfectly circular openings are exactly 1 inch in diameter, just to piss off both metric and imperial aficionados.
- xyzzy_plugh 3y agoIt's my understanding that the latency is approximately equivalent to the speed of sound as that is a function of stiffness and density. There's some detail missing still. What's the temperature of the water? How long is the puddle (or rather what's the total volume)? What's the surrounding material? I'd guess the limit is right depending on how much energy you can put into the water before it boils. At least several hundred megabits per second, I reckon -- I'm probably under by one or more order of magnitudes.