A Loudspeaker-Compatible Photo-Phonology

Last weekend, I gave a talk at the 10th Language Creation Conference on creating languages that do not use the human voice, in which I went over four case studies of successively more-alien phonologies. (One of which I have previously blogged about here.) Israel Noletto called it a "must-watch" for any speculative fiction writers putting created languages in their stories! Turns out, I had extra time, and could've talked about a fifth... but when I put together my abstract, I thought I'd be hard-pressed to fit 4 case studies in half an hour, so I cut it out. And so, I shall now present case study #5 here, in blog form!

After noodling over the cephalopod-inspired phonology for a while (for context, go watch my talk), it occurred to me that human sign languages and cephalopod communication have in common the feature that you can't flood an area with a linguistic signal the way that you can with a disembodied voice from a speaker system--they have to be displayed on a screen with a certain defined spatial extent, and even if it's a very big screen, the components of the signal are still not evenly distributed throughout space.

So, could we create a light-based language that is broadcastable in the way that audio-encoded languages are? And what sort of creature could evolve to use such a system? Well, trivially, yes, we can--just encode the existing language of your choice in Morse code (or something equivalent), and pulse the lights in a room in the appropriate pattern. Heck, people actually do this sometimes (although more often in thriller movies than in real life). But designing a language whose native phonology is Morse code is just... not that interesting. It doesn't feel materially different from designing a language to use the Latin alphabet, for example. We need more constraints to spark creativity here! So, what else could we do to more directly exploit the medium of non-localized light? In Sai's terms, how could we design something that is natural to the medium?

A first thought is that light and sound are both wave phenomena, and one could just transpose sound waves directly into light waves, and use all the same kinds of tricks that audio languages do... except, it turns out that continuously modulating the frequency of light is considerably harder than modulating the frequency of sound. We can do it with frequency-modulated radio, but that's still not how we actually encode audio signals in radio, and similar technology just doesn't exist in the visible range. And if we look at how bioluminescence actually works in nature, no known organism has the ability to continuously modulate the frequency of their light output; they have a small number (usually just one) of biochemical reactions that produce a specific spectrum, and that's it.

But, a bioluminescent creature could do essentially the same thing we do with AM radio: ignore the inherent wave properties of the carrier signal entirely, and vary the amplitude over time to impose a secondary information-carrying waveform, which can be considerably more complex than the binary on/off of Morse signals, and can in fact have its own frequency and amplitude components. That doesn't mean high-contrast flashes couldn't still be involved--going back to nature again, the intraspecific visual signalling of fireflies, for example, is very Morse-like. But it can have more complex components, resulting in a higher bitrate that feels more suitable for a language that's on par with human languages in utility and convenience. Biological signal modulation can be done by controlling the rate of release of certain chemicals (e.g., the rate at which oxygen is introduced into a firefly's light organ to react with luciferin), or by physical motion of shutters to occlude the light to varying degrees (a common mechanism among, e.g., bioluminescent fish whose light is produced by symbiotic bacteria).

So, now we have a single-channel frequency-and-amplitude-modulable signal; the next obvious analogy to explore (at least obvious to me) is whistling registers (again, for context, go watch my talk, or listen to the Conlangery episode on Whistle Registers in which I talk about my conlang Tjugem). However, we can't directly copy whistling phonology into this new medium, precisely because we are ignoring the wave nature of the carrier signal; for a creature with a high visual flicker-fusion rate, perceivable modulation frequencies could be fairly high, but still nowhere near the rate of audio signals; rather, frequency information would have to occupy about the same timescale as amplitude information. In other words, varying "frequency" would give you a distinction between amplitude changes that are fast vs. slow, but it would be much harder to do things like a simultaneous frequency-and-amplitude sweep and keep each component distinguishable, the way you can with whistling. You could do it with flickering "eyelids" or chemical mixing sphincters (or, as Bioluminescent backlighting illuminates the complex visual signals of a social squid in the deep sea puts it, "by altering conditions within the photophores (41) or by manipulating the emitted light using other anatomical features")--trills in human languages introduce low-frequency components of about the right scale--but just as the majority of phonemic tokens in spoken languages are not trills, I would expect that kind of thing in a light-based language to be relatively rare. (Side note: perhaps audio trills and rapid light modulation could both be considered analogous to cephalopod chromatic shimmer patterns.)

So, the possibilities for a single-channel light-based phonology are not quite as rich as those for a whistling phonology, although the possibility of trilling/shimmering does help a bit (even though, AFAIK, no natural whistle register makes use of trilling). But, while the number of channels available to a given bioluminescent species will be fixed, the number of channels that we choose to provide when constructing a fictional intelligent bioluminescent creature is not! And if they have multiple light organs that allow transmitting on multiple different color channels simultaneously, then just two channels would allow them to exceed the combinatorial possibilities of human whistle registers.

Using this sort of medium for communication would have some interesting technological implications. Recording light over time is in some ways much more difficult than mechanically recording sound, but reproducing it is trivial. Light-based semaphore code systems for long-range communication with shuttered lanterns might be a blatantly obvious technology very early in history; and even if it cannot be mechanically recorded, if someone is willing to sit down for a while and manually cut out the right sequence of windows in a paper tape, mechanical reproduction of natural-looking speech could also occur at a very low tech level (especially if the language is monochromatic). Analog optical sound is in fact a technology that was really used in recent human history, and the reproduction step for a species using optical communication natively would be much simpler than it was for us, as there's no need for them to do the translation step from optical signal back into sound.

Now, there's a lot of literature on animal bioluminescence, but not a ton on specific signalling patterns used by different species... except for fireflies. So, if we want to move away from abstract theorizing and look at real-world analogs to extract a set of constraints for what a light-based language might look like, borrowing from firefly patterns is probably our best bet. Additionally, and in line with modelling off of fireflies, I am going to avoid using polychromatic signals, and see just see how far we can get with a single-channel design. After all, I already looked at a multi-channel / multi-formant signal system in the electroceptive phonology of Fysh A. I won't be sticking strictly to firefly patterns, because fireflies pretty much only use flashes, without significant variation in amplitudes, and that would end up being very Morse-like. However, per the US National Park Service, there are some interesting variations in the flashing patterns seen in various species; for example:

• Long, low-amplitude glows (not really a flash at all).
• Single, medium-amplitude flashes with long gaps.
• Pairs of medium-amplitude flashes.
• Trains of medium-amplitude flashes.
• Single high-amplitude flashes ("flashbulbs").

I see a pattern going on here that may just be a coincidence, but seems like a plausible restriction on a bioluminescent alien: for a creature like a firefly which is using its own metabolic resources to produce light, rather than relying on symbiotic bacteria, there may be a maximum average rate at which power can be delivered to photophores, thus implying that, while you can glow at a low level indefinitely, brighter flashes, using more power all at once, entail a longer recovery period between flashes to "recharge". So, IF. YOU. ARE. SHOUTING. YOU. MUST. SPEAK. SLOWER. This is analogous to the amplitude-frequency dependence seen in the Fysh A electroceptive phonology.

So, let's go ahead and define three amplitude bands that phonemic segments might occupy, analogous to the frequency bands that organize whistling phonologies:

1. A low band, which allows continuous glows and smooth waves.
2. A middle band, where we have to pause between blinks, but we can blink fast enough for multiple blinks to constitute a single segment.
3. A high band, where recharge pauses are too long for sequential blinks to be interpreted as a single segment.

These are sort of analogous to "places of articulation". Then, we can also define attack/decay characteristics for each blink--something like "manners of articulation":

1. Slow attack vs. hard attack
2. Slow decay vs. hard decay--only available in the low band; the upper bands only allow hard decay, since they use up all the luciferin!

And, furthermore, we can have a distinction between:

1. "Tapped" -- a single amplitude peak.
   
2. "Trilled" -- two or more close-spaced amplitude peaks (not available in the high band)

And, in the low band only, a unique distinction between short peaks and long peaks.

So, now we can map out the complete set of distinctive segments that might exist--the alien IPA!

1. Low
1. slow, short, slow, tapped
2. slow, short, slow, trilled
3. slow, short, hard, tapped
4. slow, short, hard, trilled
5. slow, long, slow, tapped
6. slow, long, slow, trilled
7. slow, long, hard, tapped
8. slow, long, hard, trilled
9. hard, short, slow, tapped
10. hard, short, slow, trilled
11. hard, short, hard, tapped
12. hard, short, hard, trilled
13. hard, long, slow, tapped
14. hard, long, slow, trilled
15. hard, long, hard, tapped
16. hard, long, hard, trilled
2. Mid
1. slow, tapped
2. slow, trilled
3. hard, tapped
4. hard, trilled
3. High
1. slow attack
2. hard attack

And we could also have phonemic lengthening of the darkness following a hard decay for the tapped segments in the lower bands, which would give us an additional 10 possible segments, for a total of 32. Note that there's not really anything here that corresponds to "vowels". You might try to think of the low+long or low+slow-decay+trilled segments as vowels, or at least continuants, but they don't have the amplitude peaks that we would typically associate with human vowels as syllable nucleii. In fact, the whole basis of human syllable structure is missing! Instead, we might organize segments into larger units based on what kinds of segments can start or end those units--kind of like I did in Fysh A with initial and non-initial segments. The higher amplitude bands make it harder to follow up quickly with additional segments, so it would make sense if those are finals in larger, syllable-analogous units, and we end up with alien syllables that terminate in amplitude peaks rather than having them in the middle--kinda like all of their syllables are "CV" (but recall that we don't actually have a good analogy for vowels here!)

Now, with 32 different possible segments to choose from, with varying degrees of distinctiveness, not all languages in this phonetic space will use all of them, or choose exactly the same subset--just like human languages don't all use every possible human spoken phone! In particular, the low-band segments will be the most difficult to distinguish on average, due to being the "quiet"-est, so I would expect languages to vary significantly in exactly which low-band segments they utilize.

For purposes of this sketch, I'll select the following phonemes for maximal distinction:

1. Low
1. slow, short, slow, trilled - <w>
2. slow, long, slow, tapped - <r>
3. hard, long, slow, tapped - <t>
2. Mid
1. slow, tapped - <d>
2. slow, trilled - <rr>
3. hard, tapped - <k>
3. High
1. slow attack - <b>
2. hard attack - <p>

Plus long <tt> and <dd>, exploiting the geminated-darkness feature, giving us a total of 10 distinct phonemes. As in the canine phonology sketch, that's not a ton (actually less than occur even in Rotokas, with its famously small phonemic inventory), but if we look at organizing the language in terms of possible syllables rather than possible segments, things look better. If we specify that every syllable must have a rise from a dark segment to a bright segment, and terminates with the brightest segment, as soon as we see a drop, then we get the following possible syllable types:

L>M: 16 possible syllables
L>H: 8 possible syllables
L>M>H: 32 possible syllables
M>H: 8 possible syllables

For a total of 64--and that's without allowing multiple segments of a single type per syllable! If we allow clusters of low or mid segments, we get multiplicative gains. Again, different languages of this same theoretical species could vary in what kinds of clusters they allow, just as, e.g., Russian differs from Hawai'ian, so perhaps there are small-phonology languages that allow no clusters, but for convenience let's say that in this sketch we'll allow either two low segments or two mid segments per syllable; then we get:

LL>M: 64 possible syllables
L>MM: 64 possible syllables
MM>H: 32 possible syllables
LL>M>H: 128 possible syllables
L>MM>H: 128 possible syllables

And suddenly, it has become impractical to write with a syllabary!

After my LCC presentation, I had a conversation with Biblaridion in which he pointed out an aspect of all of these non-IPA-codable languages that's directly relevant to writing stories with them: who can perceive them, and who can produce them? Audio and visually-coded languages like the canine sketch, the cephalopod sketch, and Tjugem can all be perceived by humans, so we could in principle develop receptive multilingualism in them, even if we couldn't produce them (and in the case of languages like Tjugem, we can even learn to produce them, even though they don't use typicaly human phonemes). This "firefly" phonology falls into that class as well--if humans can learn to decode morse code, surely we could learn to understand a firefly phonology, but we couldn't reply in the same language, or at least not in the same modality, without technological assistance. Fysh A presents a more extreme case--if there were, say, some intelligent star-nosed moles with electroceptive noses inhabiting the Fysh's world, they could gain receptive competence while being mute, but humans can neither produce nor even perceive the language without technological assistance. This suggests a new pathway for developing alien creatures: decide what communicative barriers you need in place to drive the plot, pick a modality that makes that work, and design your creatures to make it plausible for them to communicate in that modality. In fact, on further reflection, this seems to be exactly what H. Beam Piper did for Little Fuzzy (and you thought I would get through this whole post without an affiliate link! ha!)--the Fuzzies do communicate with sound, but in a frequency range that humans can neither hear nor replicate!

Reactionless Drives & Over-Unity Devices

So, IVO Ltd is getting ready to launch the IVO Quantum Drive, based on the theory of Quantized Inertia, into space., as a fuel-less, pure-electric method of satelite propulsion. The company claims that this "is not a reactionless system" and that they can "move spacecraft without fuel and without violating Newton’s laws of motion", but... it's not at all obvious how those two things can both be true at the same time.

It certainly looks like it would violate conservation of energy, conservation of momentum, and conservation of angular momentum, so I fully expect it to not work. If it does work, it'll increase job security for a lot of physicists, and either overturn all the basic conservation laws, or require explanation of why it's not really violating them after all; maybe space is actually quantized in a way that breaks the assumptions underlying Noether's theorem; maybe it's dumping momentum somewhere else in place of dumping it into local reaction mass; maybe the total energy of the universe is zero, and extra energy produced by the thruster is balanced by negative energy in the gravitational field. [1]

But regardless of how that all shakes out, the claimed effect of an IVO Quantum Thruster is that you put a particular amount of electrical power in, and you get force out, in a fixed ratio, without expelling any reaction mass. And that has implications.

It turns out there is one kind of fuelless thruster that really exists: the photon rocket. Or in other words, the flashlight! Photons have momentum, and apply forces, and you can make them with nothing but electricity--no need to carry fuel. That's why solar sails work. But, flashlights produce extremely tiny amounts of thrust per watt--obviously, because you don't have to worry about recoil when turning on a flashlight! In fact, a flashlight (or anything else that produces light pointed mostly in one direction) only produces about 3.33 micronewtons of thrust per kilowatt--or, in other words, requires 299,792,458 watts to produce 1 newton of thrust! If that's a familiar-looking number to you, that's because, in SI units, a watt divided by a newton has the same units as velocity, and the number you get out for the ratio of power to thrust for a photon is, in fact, the speed of light! 299,792,458 W / 1 N =  299,792,458 m/s.

If your fuelless thruster produces that amount of thrust or less, you might as well just use a flashlight. And if you are getting the energy to power it from solar panels, as IVO is, then you might as well use a solar sail, to get double the momentum from the bounce! If you can produce a better power-to-thrust ratio than that, then either you have disproven relativity and established the existence of an absolute reference frame, with absolute motion altering the power requirements of your device... or, if you have a fixed power consumption and a device that respects Galilean relativity, you have a free energy machine. A perpetual motion machine of the first kind. An Over-Unity Device. Maybe it's stealing energy from elsewhere in the universe, maybe it's separating negative energy in the gravitational field, but however you resolve the problems it has with Newtonian mechanics, you've got a device that can output more energy than you put in, without fuel.

Why? Simply because, given constant acceleration under a constant force, the energy consumed by the device grows linearly, but the kinetic energy of the device grows quadratically! Thus, there exists some critical speed at which the curves will cross, and the next incremental increase in speed from activating the thruster will result in the device gaining more energy as kinetic energy than it took to power the thruster to produce that acceleration.

So, why can't you turn a flashlight into an over-unity device? Well, we can calculate the critical speed with some pretty basic Newtonian mechanics. The work done by a force is force over distance. If a particular force is applied over a particular distance over a period of time, we get power: work done per time. So we just need to find the speed--distance over time--such that a force applied at that speed produces the same amount of power going into kinetic energy as it takes to power the device. With a little algebra, we get:

E = F * D
E/t = F * D/t
P = F * V
V = P / F

In other words, the critical velocity is the per-newton power consumption, and as we saw above, for a photon rocket, that is the speed of light! A flashlight can't go faster than the speed of light, because nothing can go faster than the speed of light, so you can never meet the conditions to produce excess energy. But if thrust per watt goes up, then the critical speed goes down, and then you've got an over-unity device. [2]

So, if the IVO Quantum Thruster, or some other fuelless propulsion device, actually worked as advertised, how could we use it to engineer a practical power plant?

Let's start out by defining some useful variables and formulas:

Pi: the electrical power input to the thruster.
η: the ratio of force to power input, such that Pi*η gives the thrust.
Vo: the velocity of the thruster under power-producing operation.
Pk = Pi*η*Vo: the power delivered as kinetic energy to the thruster (and any supporting structures).
ε: the efficiency coefficient for converting kinetic energy back into electrical energy.
Pe = ε*Pk: the electrical power produced by the device.
Po = Pe - Pi: the usable output power of the device, after some electrical power is used to continue powering the thruster.
G = Po/Pi = ε*η*Vo - 1: the amplification gain factor, or ratio between input and output power.
Vg = (G + 1)/(ε*η): the velocity required to achieve a desired gain factor after accounting for inefficiencies in the equipment. When G = 0, this is the minimum operating velocity.

The IVO thruster is supposed to have a max η of 52 millinewtons / watt. That is a ridiculously huge value. The Rocketdyne F1 engines which powered the first stage of the Saturn V rocket had a thrust-to-power ratio of about 0.77 millinewtons / watt, less than 1/65th as much. That makes the IVO thruster about 15,616 times more performant than a flashlight, which should be the physical limit, according to currently-known-and-accepted physics. In other words, if these thrusters actually work, they would not just be useful for stationkeeping and orbit boosting of satelites--you could replace a rocket enginer withem, cut the fuel load by a factor of 65, run the remaining liquid hydrogen and oxygen through a fuel cell to produce electrical power to run a bank of quantum thrusters, and use that to launch an entire Saturn 5 into orbit. And if we can build a free-energy device, we don't even need the fuel cells, so continuing with that...

Mechanical-to-electrical conversion efficiencies for alternators can be pretty high--80% to 90%--so let's go ahead and set ε to 0.8. This gives us a minimum operating velocity (with zero gain) of just over 24 m/s. Not all that fast! 

So, suppose we set our operating velocity at 30m/s. That gives us a gain factor of just under 25%. If we design for 20 watts input power, producing just over 1 newton of thrust, we will thus generate just under 5 watts of excess power.

Now, 30m/s isn't ridiculously fast, but it is fast enough that building a linear track to shoot the thruster down would not be particularly convenient. Additionally, using a linear generator to recover excess energy would require pulsed operation, with time to reset the thruster at the beginning of the track after every run, or to slow down and reverse direction. So, let's just bend the thruster path into a circle! If we swing it around an arm with a 0.5 m radius, for a generator 1 meter in diameter, we get a radial acceleration of just under 184g. That might sound like a lot, but tiny benchtop laboratory centrifuges regularly get up to several tens of thousands of gs, and SpinLaunch is trying to build a centrifuge that can hold a small rocket under 10,000g. So, building a centrifuge that can hold a IVO Quantum Thruster under 184g seems very doable, and then it can just spin the shaft of an off-the-shelf alternator to produce power. 5 watts may not seem like very much, but suppose we increase the input wattage with the same gain factor? Stack up thrusters so that they can convert 800 W (about the power consumption of a typical microwave oven), and we'll get 198 W out. Increase Vo to 100 m/s, and the gain jumps to 3.16, corresponding to an output of 2528 W, and a load of only 2041g on the centrifuge. You'd want to armor the casing for this thing, but note that, unlike a flywheel battery, this thing isn't meant to store energy in rotation--so you'd want to make the centrifuge structure as light as possible, and minimize the danger of stored energy.

Bigger devices could operate at higher speeds and higher gain factors, and thus produce even higher wattages, because centripetal acceleration for a given tangential velocity goes down with radius. Suppose wanted to take this basic design and scale it up by a factor of 100: a 100-meter diameter municipal power station. At 30 m/s, that gives not-quite-2-gs of acceleration, but 100 meters is also the planned size of SpinLaunch's rocket centrifuge, so if we assume we can build for 10,000gs, that gives us an operating speed of just over 2,210 m/s, and a gain factor of 91. With space for a hundred times more thruster units around the rim, Pi goes up to 80kW, giving an output of ~7.28 megawatts--enough to power nearly 6,000 average American homes.

Now remember, these things wouldn't just violate conservation of energy--they violate conservation of angular momentum too, as a direct consequence of violating conservation of linear momentum. That introduces an entirely new sort of environmental hazard--it would take a long time, but a large number of these sorts of generators, if the fleet isn't properly balanced, would eventually start to have a noticeable impact on the rotation axis of the Earth! On shorter timescales, they would apply inconvenient continuous torques to any spaceships using them for power. Thus, you'd probably want to always build them in pairs, or build units with two counter-rotating coaxial centrifuges, to keep the accumulation of excess angular momentum at zero.

Now, suppose that the IVO thruster does end up failing, but you still want to use this idea for a science fictional device. Maybe you want to go with a less ridiculously aggressive efficiency for your fictional thruster--something comparable to a Rocketdyne F1, for example: η = .77 millinewtons / watt. Keeping our ε value of 0.8, that gives us a minimum operating velocity of 1626 m/s. A one-meter diameter centrifuge won't do in that case! You're looking strictly at larger-scale installations. Even a 100-meter centrifuge would already be operating at well over 5000g with a gain factor of 0! And handling higher gs is actually harder at larger sizes, since the larger centrifuge structure has to support itself under high accelerations as well as the constant-sized functional component--the thruster. If we go up to a 200-meter diameter installation,  we could get an effective operating speed of 2220 m/s, for a gain of ~0.37, and an output of 58.6kW for a 160kW power plant, with accelerations just over 5000g--doubling the size of the centrifuge arms, but halving the acceleration they are under.

For more engineering safety margin and higher gain factors, we have to go bigger, and then taking up all of the space inside a gigantic disk for centrifuge arms starts to seem inconvenient--not to mention the mass of the centrfiguge structure itself! You don't want to have to lug all that around in the middle of your spaceship! As assumed η values go lower, the minimum viable size of a power plant goes up, and we transition into a regime where fewer and fewer spaceships can make use of them at all, so you've got an excuse to keep spaceships using other power sources while ground-based facilities can use giant free energy power plants. But remember, we don't actually care about storing kinetic energy, so we want to cut down on mass anyway--and all of the over-unity power generation happens in the reactionless thrusters out on the edge. So what if we throw away most of the centrifuge, and just have a ring of thrusters spinning in a circular track? Now, we can build large, spindly ring-shaped power plants with a gigantic hole in the middle that you can fit the rest of a spaceship in! Or giant ground-based rings, several kilometers in diameter, with dirt-and-rock backed tracks holding back rings with thousands of gs, and a city built inside--if anything goes wrong, the ring will explode outward leaving the ship or the city in the middle unharmed. And with all that extra space to stack more thruster units, even a fairly small gain factor could get you gigawatts of power output. 

[1] It is generally believed that it should still be impossible to produce energy this way, even though it doesn't technically violate conservation, because if you can separate the vacuum into negative gravitational potential and positive useful energy, that would make the vacuum unstable, and that would be very bad for existence. But if the separation requires a macroscopic machine to achieve, and can't occur as a result of local single-particle interactions, we don't need to be as worried about triggering accidental vacuum decay.

[2] This paper (also linked previously) derives a value for the critical speed that's twice that big; that's because it is calculating a slightly different thing: the speed you have to accelerate to for the instaneous kinetic energy of the device to exceed the total energy used to accelerate it thus far. But, the point at which kinetic energy begins accumulating at a faster rate than energy is put in occurs significantly earlier.