Now, for something really bizarre, how do magnetic and electric fields affect the freezing of water (or other materials)? There is significance evidence that magnetic and electric fields can affect freezing of water, sometimes in bizarre ways.

"Frequency pulling". It happens with electronic oscillators, metronomes, pendulums, and most oscillating systems (simple harmonic motion). That's the bane of cryptographers attempting to use Free Running Oscillators as a True Hardware Random Number Generator. Such free running oscillators tend to lock into synchronization, usually at a harmonic or subharmonic of their oscillation frequency, and synchronized oscillators do not produce random results. And, it's difficult (damned difficult!) to have an array of 32 free running oscillators which have their frequencies not harmonically related, or even being close to harmonically related (So says the Voice of Experience.). https://en.wikipedia.org/wiki/Hardware_random_number_generator#Free-running_oscillators-based_RNG That was also a problem with radio receivers using pentagrid frequency converter vacuum tubes, since a strong station could cause frequency pulling of the local oscillator, causing mis-tuning effects. That's one of the reasons that upper end communications receivers preferred to use other types of frequency converters, where the local oscillator is completely separate from the frequency mixer stage, often at the expense of requiring another vacuum tube. And, since vacuum tubes were expensive, consumed a fair amount of power, and real estate on the receiver chassis, that could increase the size/cost of the receiver. That was especially true for receivers which employed double- or triple-conversion. https://en.wikipedia.org/wiki/Pentagrid_converter#Pentagrid https://en.wikipedia.org/wiki/Superheterodyne_receiver#Multiple_conversion

@Patrick Barthelow Most of those simplistic bugging devices can be found fairly quickly with a sensitive RF spectrum analyzer. The harder ones to find are the ones which employ burst transmissions, since they aren't always emitting signals. Additionally, passive devices, such as "The Thing" employed by the Soviets to bug the US Embassy in Moscow are quite difficult to find (or, at least, they were in that era). For a really talented hacker, the ideal would be to inject data into the aircraft's existing telemetry systems, so as to remain hidden. For example, modern aircraft engines provide telemetry directly to stations on the ground (via satellite links), to provide real-time engine health monitoring. What if a hacker found a way to insert an additional data packet into that telemetry stream? https://www.google.com/search?q=aircraft+engine+telemetry One does wonder, though, whether the engines on Air Force One have had the telemetry systems disabled, to prevent tracking the plane? I'd be MUCH more worried about a device in the plane's avionics, which, when it receives a coded signal, would take over from the pilots, and divert the plane into a subterranean trajectory. Those would be MUCH more difficult to find, given that they only listen for a coded signal, and would normally not interfere with the plane's avionics. And, with all of the electronics in modern plane avionic systems, such it not beyond the realm of possibility. Consider this, for example: https://www.npr.org/2015/05/19/407868096/fbi-probes-hackers-claim-he-took-over-planes-engine-controls

Oh, if you have any contacts in the Secret Service, or military (Air Force), feel free to forward this to them. I think we're all interested in protecting the president.

@Patrick Barthelow Sadly, though, we have atrocities such as the "No Child Left Behind" act which effectively penalizes gifted students, in favor of ensuring that the dumbest kids are offered assistance. Don't get me wrong. I don't think that withholding assistance from the dumb kids is good. But, there should be a parallel where additional effort is made to promoting the gifted students. Of course, there's only so much funding to go around.

One problem, though, is that whenever you convert energy from one form to another, there's a loss of efficiency. In this case, they're going from heat energy, to mechanical energy, to electrical energy, with a corresponding loss at every conversion. And, of course, with any system involving mechanical motion, there exists the potential for producing sound and/or vibration, which, as has been mentioned, is deadly in certain marine environments. As a result, modern submarines use "rafting", where the mechanical components are mounted on rubber shock absorbers, to keep the mechanical motion-induced sound from radiating into the ocean, although this adds considerable weight and complexity to the system. Even something as simple as the water-filled sonic dampers, as developed by British naval cook Thomas Lawson, which resulted in a significant quietening of British warships during WW2, added a fair amount of weight, even if they were conceptually rather simple. https://www.youtube.com/watch?v=5llr0axQ30A One solution is to go directly from thermal energy to electrical energy, such as with a Seebeck cell. Somewhere, I have a collection of Seebeck/Peltier cells. I need to find them, and start doing some work with them. The problem, though, is that most of these are reasonably low powered devices, and, even worse, tend to only produce milliVolts per junction. Even an array of 144 of them will only produce less than a Volt, given a modest temperature differential, and it's traditionally been difficult to work with such low voltages, even given a decent current capacity. I just recently (within the last week) obtained a board with a Linear Technologies LTC-3108 Ultra-Low Voltage switching converter. This will let me take the sub-1-Volt output from an array of 144 Seebeck cells (which are typically constructed from Bismuth Telluride crystals) into a usable voltage (5 Volts), which will run some solid state logic devices. These should be wonderful for constructing remote, unattended environmental monitoring devices, driven by the heat of sunlight, or from geothermal sources.