You could easily have a bioengineered weapon that could kill off an entire planet. Given the level of tech on display here, there is no reason it couldn’t be something with a long incubation period before symptoms occur, or allow for it to spread worldwide before it self triggers a lethal change like releasing some cytotoxic proteins that result in sudden death. From a biological point of view it’s actually easier to consider the feasibility of something like this ; something 100x more contagious than measles, lethal as rabies, spreads while asymptomatic etc. the idea of a virus that can instantly takeover a brain(there needs to be some latency period for it to multiply or something at least , if we are trying to be realistic ) and somehow transmit signals across radio waves is of course silly.
I think the reason they didn’t go that route is that isn’t the narrative gilligan is trying to create , it’s a completely different show at that point. Call me out if I’m wrong later but I think he is uninterested in the origins of this thing, and I doubt he will ever explore that other than dropping a few vague /indirect hints. He seems much more focused on carols character and how she approaches this situation as opposed to the black dude and others
First off yeah I agree I don't think the point of the show is to discover any of that, but it certainly is a large portion, if not the primary purpose of discussing the show on forums on the internet. This isn't lifetime we aren't going to start a knitting circle and start discussing how carol feels about being so alone.
second, we've all played plague inc on our cell phones 10-15 years ago or whenever it came out, we know the drill, and no, i posit that this type of virus, a super pacifist hivemind, is perhaps the most effective world ending virus there is. Certainly more effective than any other type of just normal "lay dormant then kill everyone later" type.
You have the problem of escaping containment, which no "lay dormant until X and then kill" virus escapes, ever. They monitored the test animals, if nothing happens, then they destroyed the animals. Either you lay dormant too long and you are destroyed when the animals were, or you killed the animals in which case, nobody starts injecting people with it. It's a total non-starter.
But ignoring that, lets say you did manage to magically escape containment. If you are completely asymptomatic you have incredibly low transmissions rates, like only sexual contact or direct skin to skin/fluids transmissions? In that case, you never get a chance to infect the whole world before you start killing. You could have an incubation time of 10 years and still not infect even half the planet if you have no lines of transmission. So no matter how long you lay dormant, once you start killing, you don't kill everyone and society keeps going or starts over. Or you have some symptoms, sniffles, a cough, a rash that people scratch, etc something to increase you infectivity vector, which increases the rate that you spread but also increases the chances that you are detected and cured before you kill.
Either way, you aren't ever going to get greenland, the space station, submarines, etc. Then you've got the tens of thousands of humans who are part of uncontacted tribes throughout the amazon, parts of africa, north sentinel islands, etc. More than once humanity has been brought to the brink of extinction in our history, in the past we've had as few as 1,280 individual humans left and here we are, a few thousand years and 8 billion people later. You have to infect everyone. The only thing that is doing that is a virus that can think, which this is scifi so yeah, a hivemind. There's 2 types. crazy zombie murder machines, borg, you will be assimilated, etc which instantly all non-infected are hostile too and start murdering all the infected, or super sneaky helpful friendly non-threat like the one this show uses which was able to infect and spread throughout a military base for 2 months before it was detected, which was long enough for it to have escaped and spread throughout the world before the military could stop it.
Also keep in mind the progenitor of the virus as a bioweapon had no idea how effective it was going to be, how long the hivemind would be able to perfect transmissions before they were discovered, etc. It could have only infected half the planet and the other half could have ended up immune, for example. Only the super helpful friendly servant style hive mind is sympathetic enough for the immunes not to round them up and contain/exterminate/etc. If they were a hostile hivemind they would of just been shot. This way they have a chance to continue to modify the virus to try and assimilate the immunes and complete their task of infecting everyone.