Why might there be no communication between continents for centuries after a civilization collapse?

Question

Centuries ago, the world was locked in a three-way cold war scenario between three large empires with nukes. The tech level was roughly equivalent to 2000's technology in our world. Runaway climate change occurred as the three superpowers doubled down on fossil fueled development in an attempt to get an edge up on the others, various natural disasters and minor wars ended up escalating, and around 500 years ago, a large-scale nuclear war broke out, destroying all but minor remnants of the nations that fought it.

The rest of the world didn't fare much better -- the planet was ravaged by nuclear winter, agriculture could no longer support most of the remaining population, disease and conflict was rampant. Within 30 years, 95% of the population was dead, for one reason or another.

Things were tough for a while. But, as it nearly always does, life went on. Today, civilization has finally been restored to what it was before the fall. Technologically, think near future -- say (very roughly) 2050.

Okay, exposition over, here's the question.

There are basically two big landmasses on the planet. For illustration, imagine a huge continent like Africa + Eurasia together with the Americas glued alongside them, and then a smaller continent like Australia around where South America would be. So: huge diverse continent, and small, mostly desert continent, separated by huge stretches of ocean. The three empires inhabited the large continent. The small continent was mostly spared from the destruction simply by virtue of being a remote desert colony of one of the three powers that no one really cared about enough to nuke.

After the nuclear war, I want there to be almost no communication between the big and the small continent up until recently. Why might that be? Being spared from the war, the smaller continent recovered faster, so they were the first to launch a satellite after the apocalypse about 150 years ago. I want this to be a dramatic moment when people on the other side look up and see an unexpected sign of life, as well as advanced technology that they were quite far from recovering themselves. Problem is, presumably radio would have been reinvented before then, or they could simply build a ship. The desire to communicate was there on both sides, but it just was not possible for some reason. What reasons could there be?

Answer 1

Considering long wave radio transmission be pretty much 1910s, see Popov's experiments, and the fact that long wave radio signal can wrap Earth, it's pretty possible that if one side rediscovers radio, the other side would be technically able to receive those transmissions. Also the ability to transfer orders fast is what actually makes empires stand and not crumple under their own weight, thus reinventing radio communication is desired by all states, perhaps they could even coordinate research for the benefit of all sides, as this tech is pretty fundamental. The same applies to the leftover community on the other continent, so if both sides manage to initiate technological revolution, they are bound to eventually come into radio contact with each other.

The possibility is there that they have too differing languages to not being able to understand what does the other side transmit, yet locating the source of a strong radio signal is possible with a little advance past initial discovery (modified radars), thus in a matte4r of decades either side would find out that the source of transmissions they receive is off their charts, so an expedition would ensue by either side, whoever thinks that contact with the outsiders would benefit them.

Also you pretty much forget that there was an epoch of Great Geographical Discoveries, that sufficiently predates inventing radio. In case the re-emerging states would desire expansion, they will commence a task to their fleet together with local shore control, in order to find any lost artifacts in the ravaged wasteland elsewhere, those that would embark on an expeditions to seas unknown might hit the forgotten continent as they collect maritime data on currents, winds, islands left etc.

To answer your title question

You asked "Why might there be no communication between continents for centuries after a civilization collapse?" - the answer is pretty simple, it took more than centuries for the remaining population to reach medieval tech level, as people were concerned with survival primarily. Having electric artifacts left over from pre-war times doesn't help unless you've regained knowledge of electricity, yet the supply chain on any modern power plant (even solar, even water-based) would not survive the nuclear war, thus there will be only remnants of stuff that was using electricity, without means to power them. (Some machines would be reworked into being powered by horse etc, yet these deteriorate too, and most easily accessible resources would be excavated, leaving no easy access to copper/iron/coal/oil aka energy sources, thus eventually all artifacts would become dust)

Seeing a satellite launched? Likely won't be noticeable

There are quite a lot of satellites in orbit currently, and while those that are on LEO would descend by drag while the civs would recover from post-war apocalypse, those that are located on SSO, let alone on geosync, won't, and those on SSO are visible at night as moving star-like objects. So people would get accommodated to seeing some moving stars, perhaps would use them to measure time, provided they would differ one from another and there isn't too many of them, and seeing another moving star might well be missed, unless the satellite would go "beep beep" and trigger radio receive across the globe. Astronomers of the mainland might be able to detect a new satellite and initiate a global outrage of "HUMANITY IN SPACE ONCE AGAIN!", yet should the mainland still be in 1500s due to technilogical drop, they won't really bother.

Also a frame challenge

"Being spared from the war, the smaller continent recovered faster, so they were the first to launch a satellite after the apocalypse" - since the pre-war civ was at least at 2000 tech level, there have to be major levels of goods transfer, at least for the power that had that colony on the small continent. As colonies usually go, the high-level industry was moved off the colony, leaving them dependent on mainland's production, in order for them to not revolt and gain independence. There might be other methods of keeping the colony in line, but all involve inducing dependency on the mainland and transfer of goods and personnel both ways. Then the war boomed, the mainland gets bombed, the colony gets abandoned, and then nuclear winter struck, leaving people in the colony without tech support for whatever installments of high-tech (power plants, computer centers, energy grid) they had, making them too go black. And getting out of black would prove very hard, especially with reduced population and deteriorated agriculture and general nature crippling. Even spared by war actions, the colony might get extinct instead of remaining afloat and with electricity.

Answer 2

Typically, such reasons are made by people, not so much limited by technology. There is basically always a way to deliver a message if someone wants it badly enough. If communication was not blocked actively, the two continents would eventually be talking to each other in one way or another.

The major reasons why anyone would block it are: taboo and crime. They can coexist, and they can reinforce each other.

If it was crime to do anything with the enemy, and the other continent was an enemy, communication with them would be outlawed. If this practice continues long enough, even thinking about such communication can become outlawed.

Of course, there will always be people who break the laws and taboos, but that is another story.

Answer 3

Oi! Those limey bogans blew the bloody world to the dunny. We're cross as a frog in a sock at em 'cause we've had a gutful. What makes ye think we would yak with the mainland? Most of them carked or gone walkabout anyway. Who here wants a mob of crooks and nippers shipping in to get on the dole? I say rack off and Hooroo to you.

In all seriousness, a grudge could be held and become a cultural touchstone/taboo. Keep the radios quiet lest the jerks who blew up the world find out we (on the smaller continent) don't have it as bad.

Answer 4

civilization has finally been restored to what it was before the fall. Technologically, think near future -- say (very roughly) 2050

-- in which case the ability to sustain contact between distant landmasses depends on what technologies remain available in 2050, which cannot yet be known. It's 27 years away; enough time to discover as well as to lose quite a few technologies. You don't even need a world-shattering calamity for this to happen; all it would take is for them to become unaffordable for long enough to cause the supporting industries to go bankrupt, and the associated supply chains to be redirected to other parts of the economy (or go bankrupt too), and then they won't be coming back due to lack of both supply and demand.

So, perhaps the technological level of 2050 is lower than today's, and restoring only to that level is insufficient to establish contact with a distant landmass.

Answer 5

Decadence

China shortly after Zheng He expedition began to close and self isolate the country. That was pushed by the necessity to keep under control a big population while preserving a strong pyramidal hierarchy. In short a decadent society. Similar examples can be found in other decadent societies. The late Ottoman empire was not so much isolated because the push by its neighbours was too strong, but it was not so open after all. Europe began its expansion shortly before the beginning of the renaissance and that expansion boomed during the renaissance. The internal structures of a society has a strong effect on its otward looking attitude.

What happened after the war? The destruction took out the tools to rebuild the machinery, but not the memory of the past abundance. The sense of loss pushed the people to rely heavily and put all their trust on few leaders and the world society fragmented in many small groups with a strong hierarchy. This pushed the few with a free attitude to rebel and flee, forming pirate groups at the borders.

Mind you, decadence might slow down the technological development, but it won't stop it completely, especially if the old books keep alive, at least in part, the old scientific knowledge.

To resume a combination of inward looking societies further isolated by barriers of pirate lands redeveloping slowly the old technology will make a good reason for the isolation.

Answer 6

Main problem is that Your small continent is close to big one. If understand You correctly then less than 1000km water gap between. That can be sailed even by canoe. Can move Your continent more far avay? Like to point nemo? and remove all islands who are beetwen Australia and Asia? If can then have 10 000 km gap. it is a big problem for ship, even big one to sail and for planes - need big fuel tanks and big plane. It will be easier to fire satelite than go by ship or plane. Then most people on small continent think that on big one is no life at all - killed by nukes and then by radiation. Go there to empty land only to die from radiation - noone will spend a peny for that.

Another thing - distance can explain why not nuked - it is lots cheapier to make 5k km range rocket than 15k range one. And is much easier defence against rocket if have 2-3 hours to intercept than when have 15-30 minutes. Even can use orbital detonted nukes to stop them.

Then have nuclear fallout - big continent will be wiped but smal one - can even not be affected at all. Hardly, but in theory can make currents and winds that way. Ofc after years backround radiation will rise 2,3 even 10 times but not to deadly level. Next that can lead to almost no dop in population. And if that continent was mostly food suply one then have good start.

If can add no fossil fuels like oil and gas but give them carbon and You have reciepe for no combustion engines, only electric and steam ones, and no planes at all. Only trains and small electric cars in cities. If want - big steam trucks and farm equipment(if You are steampunk fan :))

Ice age can be hard on big continent due to continental climate. Will be harder and last longer. If have it then need good explanation how people even survived on big continent. And if survived then they maybe have simple telescopes when satelite was fired. Maybe not even that. Think more about medieval level there.

Answer 7

Autonomous hunter-killer marine drones, and radically different human languages.

Frankly, the scenario is pretty unlikely, but this might not require too much suspension of disbelief.

They don't attempt to cross the ocean because the previous war left behind large numbers of nuclear-powered marine attack drones. These were reprogrammed by some suicidal or nihilist commander in the dying days of the final war, to simply destroy anything that strayed out of sight of land. So in the past, mariners simply set out and were never seen again. Today, the technology to fight a way through once again exists, but there would be significant cost in lives as well as money to create an armoured and weapon-bearing fleet ... and what reason to go up against an unknown but deadly threat? Might it trigger some doomsday weapon to even try?

They don't communicate by radio because they have absolutely no idea what the people on the other side are saying. In an analogue in our world, the survivors in the Americas are now all speaking Navaho. A language with absolutely nothing in common with Eurasian languages, so much so that native speakers could be an effective "encryption" technique during WW2.

Also old wartime propaganda has mutated during the dark ages into religion and legend. The other side aren't human any more. They are demons, or cannibalistic mutants. Isolation, and radio silence, were seen as the best hope to avoid the fate that the large continent suffered for its sins.

The small continent may now have developed to the point that they use low-power frequency-agile microwave radio, which can't easily be distinguished from noise and which can't propagate far over the horizon. (This is omnipresent in our civilisation: mobile phones work this way!) Historically they avoided high power broadcast radio in favour of developing the "telegraph" and had something like an internet rather earlier in technological history than we did. (Maybe they also got steampunk computing: their "Babbage" worked out binary and logic using electromechanical relays).

The big continent for its part has most of the world accessible by land transport, and knowledge that "Australia" exists was simply lost in their dark ages. They have the same problem with the hunter-killer drones, and very little motivation to do anything involving the deep seas because there is still a huge amount of land at hand to explore and colonise.

Bear in mind that in our world, when the Chinese started building ocean-going ships, the perceived threat from the unknown and from other cultures was perceived as so great that a new Emperor ordered that the fleets be destroyed, and made navigating out of sight of the Chinese mainland a capital crime. So its not unbelievable that something similar has taken hold where there is far greater evidence of what may be a deadly threat.

Answer 8

Superstition? Possibly spread by those in power whose power depends on there not being contact because of some big THING they know, or fear, would happen if there were contact.

Possibly in the war there was some bioweapon that some victims had immunity to, and they were the ancestors of everyone on Other Continent now. So people on the other continent would give you a lethal disease, maybe even deliberately, the way smallpox was weaponised in early America.

The other continent people think that everyone on your land is dead, and the place is radioactive slag? So they don't want to risk coming, and dying. Or the "dead" people don't want to tip off the others that they're alive, in case they come over and start a war that "we" don't have the resources to win.

Worst case tear up some paper and chuck it in a bucket, and draw out ideas til it makes sense. Really think about what you get.

Answer 9

During the nuclear war someone launched satellites that scramble whole electromagnetic spectrum and they are still operational. No long range radio transmissions are possible.

Seas are heavily mined and too dangerous to cross.

Why noone explores with aircraft that's harder to explain.