I had an idea last night before going to bed, that was still in my head on the way to work (usually a good sign!), for a possible science fiction novel. What if there was a pseudo-humanoid race that “saw” using gravitons (i.e. gravity) instead of light (i.e. electromagnetism)?
Small physics lesson, for background: there are four fundamental forces – in order from weakest to strongest, they are Gravitational, Weak, Electromagnetic, Strong. All of them except gravity have to do with interactions at the atomic scale; gravity is the only one that, due to some of its special properties, has major effects at the macroscopic level. If electricity and magnetism didn’t have opposites (like positive and negative charge) it would have a far greater effect macroscopically — gravity only attracts, and has infinite range, and can’t be shielded against, so it has the largest impact at the macro level.
We interact with the world using our eyes primarily, and then less so through our other senses. But our eyes, as amazing and complex as they are, are really only capable of observing a small portion of the electromagnetic spectrum. I’m no expert on how eyes work, but essentially photons (the carrier of EM) are reflected off of objects and then absorbed by our retinas. In this way, we form a picture of our surroundings – quite a detailed picture!
So what about a story in which this hypothetical g-human race had “eyes” that sensed gravitational force? I imagine the beings form sort of a 3-d “sonar” map of their surroundings, based on the raw attractive power of objects near them. They’d have to be hypersensitve (gravity is a literal hojillion times weaker than EM), and they’d probably develop “microgravity” to differentiate themselves from each other — like plumage, but due to very dense spots in their physical makeup.
One of the major challenges with writing this story will be how hard it is to SHOW things – it would take a great deal of effort to immerse a human reader in the g-human world. Also, what would the story be about? I don’t think it’s a good idea to have a human meet a g-human; I think the story is more interesting if it is entirely within the context of this gravity-sense world. Maybe there’s a fundamental problem that this species had “solved for them” by happenstance – think of their “sun” as a black hole, and that their planet is somehow in a stable orbit around it due to (some reason), that they took for granted for a loooong time. And now, it’s becoming undone and they have to figure out why their planet is sliding into the “sun” and how to stop it!
#1 by Jesse P. on 2010/01/20 - 1:07 PM
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You should read ‘Starmaker’ by Olaf Stapledon. (text is available on the web). About 3/4 of the way through, he talks about sentient stars for whom gravity forms the main sensation and the basis of their moral code.
#2 by Kelly on 2010/01/20 - 9:12 PM
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Ah, I am fascinated by this sort of thing.
The first thing that came to my mind was something you pointed out later in the post: the hypersensitivity required to discern human-scale details using gravity. I wonder how this g-sense would avoid being completely overwhelmed by the gravitational pull of their planet. The ground would obviously “look” immensely dense; perhaps that would be perceived as opacity, vs. the relative ghostliness of smaller objects? If these sensors are sensitive enough to work out relative density differences within parts of another individual (I like that, by the way), would the black hole they orbit (also a very good idea) register to their senses at all? How “bright” would it be? What about distant stars? (This seems to me like a math problem–work out what you need their resolution to be and do the math for immensely heavy distant objects using the same resolution. That’s… That’s easy, right?)
Unless you’re positing something like an eye that can detect gravitons (?), I think this would be more like a mass detector–and thus, I think it has to be omnidirectional. Would there be any reason for these people to have any concept of front and back? Might they be radially symmetrical? Can you tell a sensible story about a race that is radially symmetrical?
I also wonder whether they’d be able to tell the difference between a big far thing and a small close thing, and if so, how. They might perceive the world as a set of gravitational attractions of varying strength radiating out from themselves. That would mean that rather than being fully 3D, they might be confused by a heavy far thing behind a close light thing. Probably they could learn to see very fine distinctions in those patterns, and could discern distance based on prior experience plus clues from other senses. Or perhaps whatever system they use could exist in multiples to discern distance, analogous to binocular vision.
As far as physical structure, I can imagine it being a series of nested sensors–a big one to be pulled down instead of up, and increasingly sensitive ones nested within that sensor to detect minute local variations. I can also imagine how this could evolve from a simple “down vs. up” detector not too different from our own cochlear system, in much the same way that our insanely complex vision evolved from a simple “light vs. dark” detector.
Hm… Now I’m reading up on gravitational waves (http://en.wikipedia.org/wiki/Gravitational_wave), and I can’t tell whether it’s reasonable to imagine a “lens” that could focus them, or whether a device to detect them could possibly fit inside a humanoid body.
It might be a helpful exercise to imagine that you have no idea what sight is and try to describe it in terms of other senses and derive its properties from what you know about electromagnetic radiation.
To me, the interesting questions here are how their lives would be different from ours. What things could they perceive that we can’t? Well, they can directly see how heavy something is, which is actually pretty huge. They can discern internal densities in objects, and probably see in three dimensions in every direction out to some combination of range and mass. What things would they be blind to that we can perceive easily? As I said, it’s likely they wouldn’t be able to see the stars, or anything about the sky except (maybe) the black hole and moon(s). They would be able to smell smoke or fog, but they probably couldn’t see it.
This would certainly affect their science and technology. Their writing system could be 3D–imagine something like a woven brick, laid down layer by layer using material of varying densities. On the other hand, I would think they would need a pretty complicated setup to make anything like a computer screen. Would some scientific advances come much more naturally to them, like working out a theory of gravitation? Would others come less naturally? Like what? How would being unable to see the sky affect a culture’s development, from mythology to the idea of space travel?
Answering those questions should help with specific story ideas–what things they know about their universe, what things they might discover, how they would perceive (say) a growing instability in their orbit or the black hole itself.