Apply a high voltage to two pieces of metal, and an electrical arc will form between them -- if they are close enough together. If they are too far apart and you start to move them together, then at some point (varying with voltage and humidity of the air), the arc will suddenly strike.
The sound of this arc can be a quiet click, a loud bang, or a variety of buzzes, depending on the power supply. If the arc is sustained, the hot plasma will rise, stretching the arc until it eventually snaps, and the process repeats, this being the principle behind a Jacob's ladder.
A piano has a series of tuned strings that are hit with hammers. For Thor's Piano, the hammers hit the strings with lightning.
Each string* is charged to a high voltage. The hammers are grounded (as is the pianist). The hammers never make contact with the strings, only approaching close enough to trigger a discharge.
A mechanical linkage allows for velocity control. The head of each hammer is made from an off-centre disk of resistive material, which rotates as the key is pressed. As such, the resistance of the circuit is linked to how gently the key was pressed, with faster key presses leading to larger and louder arcs.
The sustain pedal enables a continuous discharge. With the pedal depressed, each arc strikes continuously, probably with modulation to maximise the string agitation, and potentially climbs up the string and hammer in the Jacob's Ladder fashion. This does imply that an upright piano would have better** sustain than a grand.
The soft pedal (or "practice" pedal) will not be needed, and instead has been replaced with a pedal-actuated flamethrower mounted to the instrument.
A possible variation would be Thor's Organ. An electrical arc will readily excite a column of air in a tube, with a sound similar to slapping the end of the tube with a flip-flop. With modulation of the arc, a continuous tone could form. Again, I feel like having keys that physically press the electrodes together would be the best option, avoiding the need for computers and complicated electronics, and putting the player closer to the action. In contact with it, so to speak.
* Pianos have multiple strings for most of the notes, usually two or three hit with a single hammer. It is unclear how Thor's Piano would behave with multiple independently charged strings being approached by a single hammer. The need for further research is clearly indicated.
** More lightning.-- mitxela, Aug 11 2022 Like this... https://www.youtube...watch?v=R15t7iQkV3o [doctorremulac3, Aug 11 2022] not this. https://www.youtube...watch?v=saY10AWXLIY [doctorremulac3, Aug 11 2022] I was thinking this would be a piano whose keys you play with massive mallets, (like the mouse organ from Monty Python). Still cool. See link of other music made what sparks. [+] anyway.-- doctorremulac3, Aug 11 2022 How do you electrically isolate the strings from eachother and from ground while having them taut down with their fasteners?-- RayfordSteele, Aug 11 2022 Players must wear the special insulated rubber tuxedo, sold separately.-- Sgt Teacup, Aug 11 2022 + I like the fact that more research is needed…-- xandram, Aug 11 2022 Tho you think your thor now? Jutht try playing it in a hela low key.-- 2 fries shy of a happy meal, Aug 11 2022 Yes isolation of strings will be a problem. One obvious solution is to fan the strings rather than making them parallel; the arcs can be struck at the wide-apart end and the soundboard could be at the narrow end.
How does the arc excite vibrations in the string? Would this just be spectacular and quiet? Or is there some electomagnetic force that displaces the string at the moment of arc creation?
Will there be an issue of ablaion of the string material? Is each string only good for a certain number of notes before it needs to be replaced? Does this have an implication for the length or complexity of composition? Or could the string be fed through the device from a continuous reel? If the fixed nut and the bridge are both formed as pulleys, and there is a weight system to tension the string, then tuning could be stable even as the string is incrementally wound from the feed reel to the takeup reel. Make the feed rate sufficient for long sustained notes and you will be fine. Used strings can be archived as a permanent record or recording trace of the performance.-- pocmloc, Aug 12 2022 I thought this would be a wac-a-mole style musical instrument. Where the notes would come up to be hit -- kind of like an analog Guitar Hero-- theircompetitor, Aug 12 2022 // electrically isolate the strings //
Additional spacing will be needed when compared to a regular piano, but judicious application of ceramic insulators should be sufficient.
// How does the arc excite vibrations in the string? //
It's a good question. The extreme localised heating of the air, and the resulting expansion and contraction, is the main cause of the bang of an electrical short, but how much of that would be transferred to the string is debatable. If the arc were modulated, this might be improved, but comes at a cost of complexity.
However, there will be a Lorentz force on the current-carrying string during the discharge, which will be proportional to magnetic field strength. By applying a fixed magnetic field to the strings, we should be able to boost the volume of the sound, perhaps even offering the player a volume knob that varies the field strength.
I like the idea of continuous piano wires to be consumed and eventually refilled, it adds a touch of class otherwise reserved for the carbon arc lamps of the 19th century. But it may not be necessary, as the corrosion would be mostly suppressed by flooding the piano with inert gas. This would have the dual benefit of giving a consistent arc striking voltage. Of course, for added durability, the hammers should be tungsten, and the strings platinum.-- mitxela, Aug 12 2022 //I was thinking this would be a piano whose keys you play with massive mallets, (like the mouse organ from Monty Python). //
Thor's piano. You'd push it off the stage, and it would crowd-surf for a bit - then come back so you could play it some more. The legs are a bit short because it was made too quickly.-- Loris, Aug 19 2022 random, halfbakery