How advanced could a sub-glacial civilization get before being aware of outerspace?

Question

In a world with deep subglacial seas and access to a rocky core rich in minerals with a large size (this world is a "super Europa" in orbit of a brown dwarf) a ancient, extremely biodiverse ecosystem has developed (for reasons akin to the biodiversity you see in say, rainforests; the inhabitable parts of the world are extremely populated in chemotrophic "trees" that without concern for gravity sprout from each other in a maze-like web that covers the deep surface of this world).

In this web-like forest of tubular plants, vibrant and diverse life forms who live in kilometers deep oceans exist in a environment where there is no light from the sun. Outside influences come only from the worlds around the planet in the form of tidal stress and the extremely rare comet that penetrates the shell (that would only happen on geolgical time scales).

A sapient species develops a form of advanced aquaculture, makes complex social structures and very recognizable civilizations on this world over thousands of years, developing to ever further levels of advancement down paths alien to our own. The environment is simply too different for them to develop in a way that is anything like Earth's. For example their tech would find methods of using vents and body heat to meld complex devices and various sorts of cellular systems that fill a computer-like niche. I am not sure how plausible any of this is. The premise is predicated on there being A. organic material in great abundance (due to having a ancient and complex biosphere) and B, a strong hydrothermal energy source with a mineral rich core to mine.

I believe it'd be unlikely that they'd become space faring simply because of the barriers a 12 km deep shell, radiation poisoning and frigid space have. It'd be a harder barrier to cross for them than going to space is for us because they live in much denser media than we do and we have to deal with a fair amount less radiation that they would. (Van Allen belts around dense gas giants are a pain from my understanding)

However, could these natives in spite of all that potentially be aware of their place in the universe through some other means, even if they can't get direct observation? How advanced could a sub-glacial alien civilization get until they get aware of outer space and attempt to explore it for other habitable worlds? What technological threshold may cause this and would such threshold need to be crossed in order for them not to be technologically outmatched by a human-like society?

I ask this question since I ideally want to have a situation where a interstellar society with less advanced technology opens a pandora's box by making a ancient, technologically superior but world-bound species aware of a whole universe far vaster than anything they ever imagined before and all the chaos that would ensue from that. Problem is I'm not too sure if there is any potential technologies they may develop along the way that would make them very aware of the outside universe and eventually have a culture that decides to see what's out there.

Culture is not being taken into account as much since this technology might not nessecarily be a technology dilliberately looking for anything outside their world, the discovery could be a completely unintentional result of said technology, for whatever reason it was developed. For instance in the cold war pulsar stars were discovered completely by accident.

Answer 1

Assuming they have a means of technology, then yes they could. In their world nothing would directly suggest they cannot learn about physics, maths, and develop knowledge on these to the levels we have - gravity may be hard to discover (gravity inside a sphere etc) but chemistry, technology, thermodynamics, optics, quantum theory (and eventually quantum field theory), are accessible.

So they should discover the other 3 fundamental forces we know of - namely the 3 gauge forces of the standard model - and other phenomenas such as subatomic particles, neutrinos, and fairly quickly, high energy cosmic rays. They may discover gravity by means of delicate work with masses in the lab (as we can) which would still work inside a spherical hollow world.

What this means is, although they don't have sight of the outside, they do have what they need to make equivalent discoveries . One thing they would discover would be that there are a range of waves and particles that they can detect and prove (from repeated parallax tests) must come from millions of miles or more outside their known world. Multiple detectors far apart showing that particles arrive simultaneously at all of them but not detectably converging, would show a non-close point source whose minimum distance could be estimated ("magical thinking" answers would probably be ruled out if they had a decent level of science.) Equally other particles from their sun will show parallax, although millions of miles away. So they will see multiple sources, some too far for parallax and some not, a provocative finding.

We used light to estimate how far the stars were, but they could do the same with any convenient gamma ray or other high energy source, or even their own star if their orbit was eccentric or their instruments sensitive, to tell how far the sources of these objects must be at minimum.

They would discover their world has subtle changes in heating and magnetic/electric fields, and perhaps incoming particles/electromagnetic waves, which may also prime the ground for speculating that something(s) beyond it might be responsible, and would allow them to notice regular patterns and correlations. They would also notice shielding effects of these, much as we can notice lensing around massive stars and changes in earths magnetic field. They would be able to tell that these regular changes arose outside their world.

They would also know from subatomic physics that it seems many particles have no electric charge (neutrons, neutrinos etc) and/or no mass or very small mass (photons), therefore near-infinite (or much larger than known world) range, and that they don't "fade" in travelling across their world, so they would be able to wonder where these come from and go to, beyond their known world.

They might even be able to create in some isolated area, a magnetic field strong enough to focus particles in a circle miles deep, and notice they change behaviour around 12 km deep, much as we detect the inner core by changed physical properties of signals passing through it.

They also have the ability to detect and create seismic shock waves much as we do - the reflections might be strong proof of the shape of their world and that it has a finite crust, with waves reflected continually by a curved boundary with vacuum.

They would also be able to drill better than we could - if their world is ice covered, then ice is an easier subject to affect (laser/high temperature "drill"/microwave emitter) than many other materials and they may decide to probe it. 12 km ice is a lot easier than the same depth of rock.

Core samples (well, exterior ice drilling samples) would add evidence. A core sample a few km deep isn't unreasonable and these people would find that as they get deeper, they start to find evidence of impact shock in the ice structure, dust clearly "seeded" by and associated with these will have unusual elements/isotopes, and other evidence of a violent external environment very different to the internal one.

The natural step of taking further/multiple samples will show the shock surfaces are concave (seen from "beyond") hence they represented an external event or impact of some kind. They will be able to study impact structures in ice easily (as we can) and therefore realise these imply from their features and sheer size, numerous events of very high energies not existing within and therefore the impression of high velocity external impact and the presence of some kind of outer shell.

Geometry will also play a part. Timing of electromagnetic waves will also show they live on the interior surface of a spherical shaped shell, even if they can't see it directly due to haze/distance/conditions. This will make sense in light of other discoveries.

Once they realise "something in nature other than ice" is "down" there (as opposed to mythological places or endless ice forever), and that's it is complex and intriguing, the question how to determine what it is will arise.

So if technology reaches ours, they could well be able to prove it from all these kinds of evidence all painting a consistent picture.

After that - well, even without space faring, a curious species is likely to work towards getting probes through the ice, and even a small probe will be enough to show the wider universe.

So overall, it wouldn't be hard. The main barrier isn't the ice, or the living on the interior. Its the difficulty of conceiving there could be an outside some distance below the "ground", and it might be a bigger/different/real place. Once that's challenged and evidence starts to pile up then its all but game over. I wouldn't like to be their Galileo though.....

Answer 2

If they have absolutely no pressing need to observe or interact with space, they could get fairly advanced. Depending upon how deep underwater they are, they may have issues even getting close enough to the surface to see the comet-holes, and they may need special pressurized vehicles to go in higher-up water. Technological advancement can't always be thought of as fully ordered. They could lack even basic rocket technology, but have quantum computers. Don't ask what technology they would develop based on what they have, ask what technology they would develop based on what they need.

Even if they had advanced mathematics and actively observed the stars with telescopes, the fact that they can only place telescopes in comet-struck holes in the ice means that they can't develop particularly advanced astronomy. They'd be able to dispell heliocentricism fairly quickly simply by observing the orbital periods of nearby planets. But if they have no reason to explore space, they have no reason to explore space.

Personally, I don't think it would be a technological threshold that inspires them to explore space, it's more about giving them a compelling reason to do so. On Earth, we had the space race, but that's for a species that has had pretty constant ability to stare up at the night sky. For this subglacial race, space is even more alien, simply because there is no ready way to look at it. It could potentially bear either a lot more or a lot less cultural value: on one hand, it's more of an unknown, so exploring it is cooler. On the other hand, it's more unknown, so fewer people care.

So what could space do that compels your species to explore it? If your species has telescopes looking up from comet-holes, they could see a massive comet headed for their planet, which could motivate them to invent rocketry to deal with that. I think a cooler option would be for a satellite or other nonthreatening unmanned piece of alien technology breaking through a very large piece of ice. The ice breakage could be large enough to draw a lot of attention to the debris, without being so catastrophically huge that it has significant environmental consequences.

Answer 3

Frankly, I see no reason why they would develop vision at all. Without the default condition of sunlight, there is no obvious reason why they would produce any organ which responds to EM radiation.

So, no eyes and no telescopes. Impact holes in the ice would simply be local catastrophes. Although they would probably come to an awareness of the "the top of the universe", the infrequent opportunities to explore would be handicapped by their sensoria. For mobile organisms I'd expect sonar to be the dominant sensory mode. Such sonar, optimized for the liquid environment, would be ineffective above the surface of the sub-ice liquid. Could a race overcome these handicaps? I really don't know.