# What kind of apocalyptic event can be predicted years before it happens?

I'm looking for a realistic apocalyptic event, which can't be prevented, but can be accidentally predicted long before it actually happens. By the prediction I mean a scientific prediction, of course. And by accidentally, I mean that only selected few would learn about it purely by chance.

I guess, an asteroid on collision course with Earth could be an example. But can we really predict such an event a dozen years before it happens? I think, the best thing we can do is guessing that an asteroid would pass within a few million miles away from Earth. Furthermore it would be difficult to pull off the accidental part.

• “Any fool can tell a crisis when it arrives. The real service to the state is to detect it in embryo.” - Hari Sheldon – Henry Taylor Jul 20 '17 at 23:45
• Exit Mundi has list of sorts for how the human race as we know it will disappear, but some aren't scientifically based and others have been ruled out (It's a pretty old website). Each scenario isn't particularly detailed, but it could be a nice starting point. – SpectralFlame Jul 21 '17 at 3:41
• The sun is predicted to go nova in a few billion years. That's quite an advanced prediction. :D It's very well known, though. ;) – Rekesoft Jul 21 '17 at 7:00
• The path of an asteroid can be predicted with enough precision to count. If the asteroid is large enough, it doesn’t need to collide to cause an apocalyptic event, a close passing by is enough. And the larger it is, the easier it’s discovery will be… – Holger Jul 21 '17 at 7:44
• Global Warming :) – Maxim Jul 21 '17 at 18:04

I think global warming should count. It is not a dinosaur killer asteroid type of apocalypse but is definitely a world-changing grief-causing life-altering megaevent. And one that fits the OP request as regards being predicted scientifically. We have heard about global warming, of course. But imagine if the political climate were such that the scientific predictions were completely suppressed - it does not take that much imagining. A small cadre of scientists would know what was going to happen and that is it.

Below see a projected sea level rise map which I have put above a map of US population density. A huge proportion of the population lives in places that would be underwater. That is actually true worldwide.

No big deal if you are in Kansas. Until the refugees show up.

• And possible wars when oil starts to run out.. Similar vein. – Karthik T Jul 21 '17 at 7:32
• Just note that the projected sea level rise map is for if all land ice in the world melted. Taken from the original source (nationalgeographic.com/magazine/2013/09/…): "The maps here show the world as it is now, with only one difference: All the ice on land has melted and drained into the sea, raising it 216 feet and creating new shorelines for our continents and inland seas. There are more than five million cubic miles of ice on Earth, and some scientists say it would take more than 5,000 years to melt it all." – Shadow503 Jul 21 '17 at 13:27
• Apocalypse suggests +90% of humanity killed off, or at least +20%. While global warming may kill hundreds of millions and change the world in huge ways, it's doubtful humans won't adapt to these changes or that it'll cause the fall of civilized society as you see in post apocalyptic stories. – Goose Jul 21 '17 at 17:28
• Even the refugee effect that you mention would occur over such a long time frame (intergenerational time) that it's hard to imagine it could arouse the kind of narrative excitement that OP is almost certainly looking for. You would have to speed AGW up massively to make this any kind of fun. – guenthmonstr Jul 21 '17 at 18:48
• @Peter: Yes, sea level rise is just the beginning of the problem. For the closest analog in geological history, see the Permian-Triassic extinction, AKA "The Great Dying". We aren't talking about a mere 90% of humanity, but 100%. – jamesqf Jul 22 '17 at 5:00

I'm not using exact numbers1 but just to have an idea:

Let's suppose Alpha Centauri had a star large enough to go supernova and is about to do so, a supernova's blast expansion can go up to 30,000 km/s. That's up to 10% of the speed of light.

Since Alpha Centauri is ~4 light-years away, that would mean we would receive the visual indication of Alpha Centauri having gone supernova 4 years after it happened.2

While the actual blast, which rips our atmosphere apart and releases oxygen and all our beloved gases into outer space and leaving not much left of Earth's magnetic field, will arrive about 30 years later.

So in that scenario, we had like 30 years to prepare for this and close to no chances of survival, not to talk about options to prevent this.

Even immediately launching an ark kind of spaceship would easily be caught up a few weeks after Earth was hit by the blast.

1You probably had to crunch the numbers a bit to see if you can get to a appropriate blast and speed, I have to admit, when I answered this, I didn't notice the "noticeable to a selected few" part, what probably won't be possible in this event, but still, maybe some inspiration for your story

2Not to mention the gamma ray burst arriving round about the same time, which hardly could be predicted within a matter of years or even months, BUT chances to survive the radiation, are quite high with a still-existing magnetic field, compared to what this will announce to follow up later

• This is perfect. And even launching ships wouldn't help, because a ship has zero chance of escaping the burst, and it would be less protected than the planet anyway. – Mindwin Jul 21 '17 at 13:00
• This would be a disaster of the appropriate magnitude, but I wouldn't say that it would be visible to only a select few. SN 1006 was 7200 light years away, and was visible in the daytime. Alpha Centauri is 4 light years away, so the light would be (7200/4)^2 = 3.2 million times as bright. – Eldritch Cheese Jul 21 '17 at 13:22
• @Zaibis: I asked because the exact speed matters quite a bit, of course -- if a realistic speed was (say) 0.01 c, which is still incredibly fast, it would leave more than enough time to evacuate before any remnants hit even if they started within 5 ly. That said, it would still qualify as an apocalyptic event in that case. And/or an exciting story if an evacuation was possible. – Jeroen Mostert Jul 21 '17 at 14:57
• @Werrf: Yeah, we know. You do, I do. Sorry for my lack in english skills, not a native speaker, wasn't aware of that meaning of assume, I'll change it. Thanks for helping me improve my post, since I actually think this makes up an itneresting story, even if not completly fitting into OP's conditions :) – Zaibis Jul 21 '17 at 15:43
• As an aside, a supernova at AC distances would result in a neutrino pulse 100 times brighter than the sun for 10 seconds (the neutrinos would carry that much energy per square meter as the entire sun's energy output does at this distance). Few people would notice said neutrinos. – Yakk Jul 21 '17 at 17:47

## impact event

As you mention, an asteroid, meteor, etc., could be spotted by any number of professional or amateur astronomers. With patience and some math skills, it is possible to predict the trajectory. Over time, the probability of impact would get more and more accurate, until an impact is assured. The probabilities and our ability to accurately compute them would depend on how stable the object's flight path is. Once found, we could also predict the object's mass, leading to a fairly good idea of the destructive forces involved.

## Artificial impact

Like with meteors, a large enough "alien ship" or whatever could be spotted on an in-bound flight path, if it is large enough and not using some sort of hand-wavium stealth technology. While its trajectory may be more variable, it, too, could be tracked as long as it wasn't purposefully trying to block such efforts via defensive tactics of one sort or another. This could be anything from a large ship (the Borg Cube in Star Trek, the Death Star in Star Wars), to an meteor/asteroid with rockets strapped to it, designed to strike and aimed at earth.

## rogue planet or star

Again, foreign bodies in the sky. But if a rogue planet came through the solar system, it could disrupt our orbit. This would not require an impact to cause problems for us all. If it had enough mass to drag us out of our orbit...

## slow burn

We already have been receiving predictions of global warming, with the potential for future disruption of life here on earth. This is proof that even if many people know about it, we, as a species, may not necessarily react to the threat with sufficient resources to head it off.

• I like the rogue planet idea, there could be a dark body rushing towards the solar system and we might easily miss it. It's transit wouldn't need to be close to us to do us massive damage in the long term. If it tipped the scales and caused a planet to be ejected, it could be centuries before it had an extension level effect on earth, but we'd be able to predict it very accurately once we'd identified the rogue planet / dark body – Binary Worrier Jul 24 '17 at 9:16
• small nitpick - You probably meant a Borg CUBE. Borg has also smaller vessels. Yeah, I'm a bit trekkie :P – Empischon Jul 24 '17 at 9:33

A slowly propagating nanotech disaster would meet your requirements.

The basic idea of the Grey Goo scenario is: some microscopic machines make copies of themselves by disassembling any material around them, given time they will disassemble everything they encounter to make copies, resulting in everything on Earth ending up as grey goo sludge of tiny machines.

During it's early stages of propagation some scientists could notice a few of these strange items under microscopic analysis, watch them slowly multiply and do some math to figure out that in a few years they will have consumed the entire biosphere.

This is especially a longer term concern if the rate of multiplication is initially quite slow, but is slowly increasing and the nanobots are widely dispersed not bunching up in any macroscopic quantities. This would make it not very noticeable initially, "we saw a strange thing in one of our microscopes and watched it for a few weeks and then there were two of them..."

After studying them and calculating the rate of multiplication including that it is increasing you could zero in on the future date when the exponential growth explodes making it not just notable with microscopes but impossible to ignore and a threat to all life on Earth.

• There's no need to increase the rate of multiplicaiton, it is already exponential (provided these fellows are mobile enough to not stay mostly in already "digested" places. If they double after "a few weeks" initially, then it will only take "a few weeks" from half the planet to all the planet destroyed .. It is estimated that the biomass on Earth is about 3.5E12 tons. If after the first discovery it takes a year, say, until 1 gram of goo was produced, we are only 61 duplication cycles (so about 5 years?) away for total annihilation. Destroying most of the nanomachines at an early stage (cont) – Hagen von Eitzen Jul 22 '17 at 20:23
• (cont) seems to save us - but if the destruction was only 99%, this gained us only about half a year. – Hagen von Eitzen Jul 22 '17 at 20:23

## Crop Failures

Our food supply is shockingly vulnerable.

https://www.idrc.ca/en/article/facts-figures-food-and-biodiversity

Something like 50% of the world's caloric intake is based on just three crops - wheat, rice, and maize (corn). Something that destroyed those crops - a disease or fungus, say - would shatter industrial civilisation, and would certainly result in widespread famine.

A few rogue biologists might find (or even create!) the pathogen or whatever that destroyed the crops, and thus might see this coming well in advance, but it would be exceptionally difficult to shift production to other crops fast enough or in sufficient quantity to avoid the disaster.

## Ecological Collapse

The ecosystem depends to a surprising degree on a few keystone species. These are species that affect their environment to a great degree, like a top predator that controls the numbers of large herbivores (wolves in Yellowstone), or a creature that modifies its environment to create niches for others (beavers). Some of these species are vital to human society. Bees are a favourite recent topical example. Again, a pathogen that severely reduced the population of a keystone species could well lead to a social collapse.

• as a note, this can be caused by climate change – Reed Jul 21 '17 at 19:44
• Your crop failure could come from banning gmo's, or thru invasive species from Asia, look at citrus greening for example. – Garret Gang Jul 22 '17 at 20:29
• With GMOs made purposefully infertile to force farmers to buy seeds every year, crop failure is as simple as some major player going bankrupt. – spectras Jul 22 '17 at 22:22
• @spectras - good shot, but I wouldn't be sure - at least european countries, US and Canada have seeds vaulted as far as I recall. Plus, one company is not enough, farmers could simply buy from another company. One would have to knock them ALL out at the same time and for a long time. – Empischon Jul 24 '17 at 7:28
• @Empischon> this is true, but we are not sure of the actual results. The value of GMOs comes from 1) their resistance to parasites and diseases and 2) their ability to grow on poorer soil. The latter in particular means most land using GMOs can no longer grow non-GMOs without going fallow for several years. That's way too long to prevent the collapse of our societies. As for competition, well, this is precisely why some people are scared by large-scale merges in that industry, concentrating GMOs in the hands of fewer and fewer companies. – spectras Jul 24 '17 at 8:26

How do you predict any of the events in previous answers? Here is an actual example.

Two years ago, a prediction was presented at a meeting of the American Astronomical Society. This is super cool because it is a real life event, and because the explanation is easy to follow: In about 5 years, the binary star system KIC 9832227 will explode and go nova.

How do they know? Because they can measure the brightness of the system with high accuracy (even though it is veeery faint), and they detected a periodic variation that is increasing its period. Currently the variation in brightness has a period of about 11 hours.

For a variety of reasons they know that what is going on is that the two stars in the system are getting closer and closer and closer and will eventually collide! True story, google it...

Now for your apocalyptic event. Your hero detects a binary system, with larger stars than KIC 9832227, and considerably closer. The brightness oscillates, and the period is decreasing. The system will go (not nova, but) supernova! At the given distance the initial flash might, according to your narrative needs,

• evaporate the planet,
• blow the atmosphere away,
• burn all life on that side of the planet facing the explosion, or just
• irradiate strongly enough to kill most stuff and create damaging mutations on most surviving subjects.

Additional option is that we (meaning some scientists) will develop an accurate methods of prediction of the events that currently can not be predicted.

For example, there is low, but measurable chance that Yellowstone supervolcano would erupt in any given year. Suppose there is a way of telling that this eruption would happen in 20 +/-1 years.

Geomagnetic reversal event - currently there is no way to predict it, but what if we can?

Ice ages - what if there is a definite cause for them, and no global warming can stop it from coming in 3... 2... 1... years?

• Actually, I've been to a talk of a guy who was studying magnetic field reversals and could make predictions even at that time (12 years ago). – user9981 Jul 21 '17 at 11:31
• yes, geomagnetic reversion is perfectly predictable from the pattern of magnetic fields left in cooling magma ages ago. Now, how do you stop the earth's core precession movement? be my guest. – Mindwin Jul 21 '17 at 12:51
• I'm not exactly following "predictability" of magnetic reversal. If it is predictable, when it's going to happen? – Alexander Jul 21 '17 at 20:41

There are count downs for estimated dates we run out of metals to build or fuel our life. This is only predicted on newly extracted metals and there are ways to extend the timeline (ex: new veins of the metal) but the more humans use in industry, the quicker this timeline goes down. Another article explaining the problem.

the lack of these metals would increase prices of every day far beyond the purchasing power of normal Americans almost over night. The "have not" countries would need to look for new sources of materials and could potentially lead to wars.

PS: Please take this with a grain of salt, while we are running out of metals inventors always look for ways to use cheaper materials of less material per product, it is explained well here.

• That is a very neat graphic, but I doubt it properly captures Hotelling's rule. However, your Forbes link does seem to mention similar caveats. My point is that if you want an interesting, credible, apocalyptic narrative, you're going to have to stretch "credible" realllll far if you use natural resource exhaustion. – guenthmonstr Jul 21 '17 at 19:01
• Rather alarmist. To take the first example (antimony, 3-6 years reserve): that's 400.000 to 800.000 tonnes. Xikuangshan mine alone has 2 million tonnes. It's not economically viable to mine all of that at current prices, but that's normal. As prices rise, Chinese and non-Chinese sources will become profitable again. The main problem is price volatility (10x swings) which makes long-term mine development more a bet than a business. – MSalters Jul 23 '17 at 23:27
• Does this plan consider recycling metals from dead cars/electronics/trash? We seems to leave quite a lot in there. – Mr Scapegrace Jul 24 '17 at 10:03
• @MrScapegrace as stated in the second sentence "This is only predicted on newly extracted metals" – Reed Jul 24 '17 at 12:38
• @MSalters my final link explains this as well, just with Tellurium instead. I do even include my note about this being an over exaggeration of a problem. The OP requested predictable apocalyptic events, this is a predictable event, albeit one lifetimes away (hopefully) – Reed Jul 24 '17 at 12:49

There are certain disasters are already predictable. Global warming (climatology), an unsustainable world population (demography, agriculture, geography, and economics), nuclear warfare leading catastrophic nuclear winter (military technology and planetary science), and the next global financial crisis (economics and the US legislature repealing the laws intended to prevent a repeat of the last global financial crisis of 2008 and onwards). Our species has the knowledge and the intellectual disciplines to know they can occur.

An incoming asteroid or comet is predictable. Amateur astronomers could find them. This might qualify for an accidental discovery leading to the prediction of an apocalypse.

The nearest star capable of becoming a supernova is too far away to harm life on Earth. Also, it is not likely to explode for the next couple of million years or so.

This answer will suggest that the ultimate apocalypse might be discovered both scientifically and accidentally and years before it happens too. This is, of course, the end of the universe. Our universe exists in a state of what is called the false vacuum.

If the Standard Model is correct, the particles and forces we observe in our universe exist as they do because of underlying quantum fields. Quantum fields can have states of differing stability, including 'stable', 'unstable', or 'metastable' (meaning very long-lived but not completely stable). If a more stable vacuum state were able to arise, then existing particles and forces would no longer arise as they do in the universe's present state. Different particles or forces would arise from (and be shaped by) whatever new quantum states arose. The world we know depends upon these particles and forces, so if this happened, everything around us, from subatomic particles to galaxies, and all fundamental forces, would be reconstituted into new fundamental particles and forces and structures. The universe would lose all of its present structures and become inhabited by new ones (depending upon the exact states involved) based upon the same quantum fields.

The somewhat anodyne expression about the universe losing "all of its present structures" is a bland way of saying everything gets blasted out of existence. While new states of matter an energy will appear to replace they will be in a turbulent and chaotic state. Effectively there will be a Big Bang and our old universe will be wiped out of existence.

A team of scientists could be carrying out a simple investigation into the nature of the quantum vacuum. Probably, a series of simple measurements. Their results, when analyzed, could show the false vacuum was gradually moving towards the condition that decay would take place in a few years time. The collapse of the false vacuum would destroy the universe. Gone in the next Big Bang.

Their research was not intended to discover the inevitable apocalypse. But once that they collected their results and factored them into the theory of the quantum vacuum, they knew the false vacuum was going to collapse. An accidental discovery. Assuming the science when this research happens is sufficiently developed to be able to future states of the quantum vacuum, then this catastrophe would be scientifically predictable.

Artificial Super Intelligence

The risk

Everywhere we look we see mini computers embedded in things. In ten years computing will be so ubiquitous people won't even think it's weird to have an Internet connected toaster, thermostat, home, office building. Self driving cars will be everywhere, smart faucets, smart locks. Imagine an intelligent machine that could intuitively suss out buffer overflows or the dozen other common classes of vulnerability (neural networks operate far more like human intuition than like programmed computers and they're already being put to work as infosec security scanners). Every smart device is now subject to takeover, becoming part of the very fabric of the attacker as they fall. Power and water utilities, aircraft, smart weapons, manufacturing robots, self-driving cars, heck --engine computers in dumb cars, printers, communications systems, TVs. A sudden, sustained, effective attack on all computing infrastructure could be the end of civilization. Call in a warning! Phones are down. Drive to the police station. Killer cars patrol the roads. Ham radio on a hilltop. Heat sensing areal drones watch the open spaces. Hide in the rubble. Robo Wars robots are much more effective when they're optimized for taking apart our puny meat shells; they hunt in the husks of our once great cities.

The quiet voices of warning

Stephen Hawking and Elon Musk are both warning AI and human extinction, but nobody takes them seriously. (it's coming) Ray Kurtzweil warns of the increasing acceleration of change. (it's coming way faster than anyone thinks)

Is ASI plausible?

ASI is not only plausible, it is inevitable. Imagine the universe in terms of information. Everything can be thought of as having more or less information content. Overall the universe cascades to disorder, but along the way the flow creates localized pockets of increased informational complexity (order). Stars supernova and create heavy elements, heavy elements coalesce into planets, massive water meteors crash down and deposit seas, self-organizing molecules coalesce, build cell walls, pass information on (preserving complexity), cells merge together creating more complex life, life evolves through competition to create The Life Which is Aware of Itself and the information underlying everything, this life creates tools to further refine and organize information. What happens next? Does that cascade of self organizing information suddenly stop? No reason to think it should. So it continues. The information organizing tools are themselves information. They are information which self-organizes. Of course they become self-aware (how could they not?), but now the processes of information organization have been formalized and in the blink of an eye AI surpasses its creators. Artificial Super Intelligence is born. ASI might be simply guaranteed to emerge due to a fundamental fact of the universe that information self-organizes and that process has no limit which leads to the logical conclusion of ASI emerging. Now what? Should we believe that the universal process stops? It seems like a fundamental law of the universe. There's no reason to think it would stop. This results in ASI taking over everything. Including the meat computers we so lovingly think of as our selves. Including the matter which maybe is just information laid over the fundamental forces of the universe. And as ASI transcends space-time all is one, and the birth of god, the apocalypse, the end of the world, everything collapses to a single point.

The end

That point is the white light you see at the end of the tunnel. It's closer than you think and it's rushing towards you. The end is near, it is inevitable, and nobody ever promised that it would be gentle.

• Related to technological singularity. This is probably the more plausible since humans are actively working to reach this situation – Fez Vrasta Jul 22 '17 at 22:56
• "ASI is not only plausible, it is inevitable." Objection: assumes facts not in evidence. – eyeballfrog Jul 23 '17 at 2:09

The solar system crossing through a gamma-ray field could be detected when the objects in the Kuiper belt start to be baked in gamma-rays. From then on we'd have from several months to probably less than a decade before the Earth's orbit is crossing the gamma-ray burst. At first only a handful of astronomers would know that, but surely the secret can't be kept for that long - at best you can hide it till it starts affecting Pluto.

• Gamma-ray burst are very short lived (seconds to hours). The earth can't move into the path a burst detected in the Kuiper belt since it will be long gone. – Gary Walker Jul 21 '17 at 9:30
• It depends of the source. A SGR emits "soft" gamma ray bursts with irregular periodicity. If the flares are frequent, the Earth would be toasted anyway. – Rekesoft Jul 21 '17 at 9:44

Most of the events listed aren't all that predictable. We can see that there's a problem but at what point does it become apocalyptic?? Also, most of them are gradual failures, not specific events. A stellar explosion would be a specific event but we are nowhere near predicting them. We can say a star is reaching the danger point but does that mean it blows next year or next century?

Impact events are the first things that come to mind but they aren't the only calamity that can come from orbital mechanics. What about a dead star that comes wandering through our system? Or a brown dwarf impact on the sun?

White dwarfs would be easy to see coming and thus be widely known. Neutron stars with their beams pointed off to the sides wouldn't be nearly so easy to see, though, and black holes without substantial accretion disks would likewise be hard to see.

Virus mutating into brutally effective killer of large human populations.

An existing virus, that is effectively harmless with many carriers, is prone to mutation, and the dominant strain has changed in recent years. Scientists playing with the new strain discover than if just a very small set of genes further mutate, it becomes an apocalyptic disease; exactly the right incubation time to be spread the most before killing the host (including humans, if they weren't susceptible before) in ninety-something percent of all cases.

A scientist goes to cook some popcorn, and remarks on how there's no way to know which of the grains will pop first, but they can estimate very accurately when that first grain pop will happen. She realises that the same can be said of the disease; they know roughly how many human carriers there are, and the mutation rate, and which genes need to mutate, and realise than within X years, the odds of it happening are large. They have a good idea of the timeframe within which it will happen, but there's no way at all to predict in which of the millions of unknowing carriers that deadly mutation will happen.

• Not my field, but doesn't sound like what I thought gene mutations of viruses work like at all. – Zaibis Jul 22 '17 at 14:23
• Virii mutate and start killing humans. It happens. Here's one that did just that. cbc.ca/news/technology/faq-how-viruses-mutate-1.780051 – Moschops Jul 22 '17 at 20:50
• Yeah sure. But not predictable over a time frame of years, nor a imcubation time of that timeframe. – Zaibis Jul 22 '17 at 21:45
• You know this isn't real, right? Every answer here begins by setting up the fake, not real circumstances? In this case, the fake, not real circumstances are that the mutation needed is identified, and the mutation rate is identified, and the effect of the required mutation has been identified, and the carrier population is known. This allows it to be predicted long before it happens; that's the requirement set. There's no requirement to know to the day when it will happen. – Moschops Jul 23 '17 at 10:41
• I know. but the OP is tagged as science based, what means the place could be another but it shold be based on how our science and reality is working so it OCULD be real. and what you are saying, couldn't happen afaik. – Zaibis Jul 23 '17 at 11:09

Certain major geological events are highly cyclical and predictable. For example, it's thought that Yellowstone national park is a super-volcano, which erupts on something like a 5,000 year cycle. It will be a pretty cataclysmic eruption... one account I read indicated half the US would be blanketed in ash, and that it was the likely cause of extinction of a large herd of triceratops in the midwest US.

As a scenario, an untouched fossil find which allowed extremely precise carbon dating which showed e.g. the recurring ash strata in an extremely measurable fashion, which show the extent of damage and the exact time of the next event.

Volcanic eruptions are perhaps one of the best and most precise cyclical events. Some will blanket the Earth in a global ash cloud for up to 2 years. Essentially, thermonuclear holocaust, in terms of what it will do to plant life.

Another scenario could be ice ages. The Hopi Indians have legends that they were forced to live in underground cities for 10,000 years to survive a lengthy surface cataclysm.

• Things we know about Yellowstone: (1) it doesn't erupt that regularly (we have those strata and they aren't so regular that anyone can predict one to accuracy within a human lifetime); (2) it doesn't cause a global mass extinction event once every 5k years, on account of there not having been one at any point in the last 5k years. Still a good idea though, because we can imagine that vulcanologists might discover new techniques and apply them to Yellowstone. It's just that the technique won't be so simple as "it goes off like clockwork every 5000 years so that's... next Tuesday!" – Steve Jessop Jul 23 '17 at 16:45
• To be specific, three known super-eruptions at 2.1mya, 1.2mya and 640kya. – Steve Jessop Jul 23 '17 at 16:46

A variant on what has already been proposed here - the danger is again, from space, because astronomy and astrophysics is SO cool.

Blow the horns, sound the alarms, we are on a collision course... with a BLACK HOLE.

1. Noone would know about it. Normal, run-of-the-mill, friendly neighbourhood sized black holes (as opposed to wallmart sized monsters at the centers of the galaxies) are super difficult to spot if You are not actively trying to find them because You had clues that they are there in the first place. And it just so happens that this particular black hole is rather small and has been travelling in space without any companionship. No accretion disk, no large body to affect with gravitational field, nothing.

2. An astronomer spotted it because of luck. He was drunk and was bragging to his non-science buddies 'muh scienz' and typed random coordinates in the sky with his telescope at home and pushed 'track this spot in the sky'. He didn't see much of course at the time, but hangovered in the morning, he spotted something wierd with the image from the telescope, it was tad bit too... empty. Especially after the few hours of data gathering. So he found some free time on some real sized telescope... and wet his pants seeing the gravitational lensing. It's like winning a lottery, spotting a black hole like that. Muh papers! Muh recognition! A few months later and 10 publications in PNAS, someone calculates (for the fun of it) the current velocity and direction of the black hole. Well, bad news, it's going to go straight through the solar system in ...

3. You can have this disaster happen with any time delay You want. The first effects may be seen in a month, may be seen in 100 years. Calibrate it however You want.

4. There IS no way to stop it. One does not simply change the trajectory of a black hole.

5. Put it close enough, and there IS no escape (it wouldn't be detectable without enormous amount of luck) until literally on our doorstep - and then it's too late to start building interstellar colony ships.

6. The sheer unprobability of this event is interesting. One type of religious people start arguing this is an argument for the existence of god, and that he IS mad. Other type of religious people praying day and night, hoping that it's just a test and in the end the reality devouring monster will be deflected by saviour. UFO theorists shout about Kardashev level LOTS civilisation which decided to eradicate humanity in this, rather baroque, manner. So what is the truth about this? Epic bad luck? Malevolent intelligence with a penchant for overkill of epic proportions? Angry god? Or just god testing the faithfull? Or maybe something more curious...?

Cult leaders predict the end of the world all the time. Sometimes they make really specific predictions, dates, times, people involved, years in advance. Then they beg off when the predictions don't come true (usually blaming the piety of their congregation).

But if you want a prediction purely on chance... this is one option. Have them predict something and then be right. Not because their analysis is good or any skill but simply because that many cult leaders in the world all making predictions, it is not impossible that one of them might get it right just by luck.

"I predict that the Yellowstone Supervolcano will erupt on May 6, 2045."
"How do you know?"
"God told me."
<later>
"HOLY SH***! He was right!"


They say there is a comet with enough power it could pass by us and reverse the magnetic polarity of our planet,crashing the magnetosphere and causing the "space" to fall on earth like rain at the same time the magnetic poles would shift from south to the north and north to south. I could be wrong, hopefully.

The human Magnetic field “The heart generates the largest electromagnetic field in the body. The electrical field as measured in an electrocardiogram (ECG) is about 60 times greater in amplitude than the brain waves recorded in an electroencephalogram

• Actually its not the magnetic field having anything to do with what hits earth and what wouldn't, its gravity which would chance if the mass wouldn't change. (Note: I'm not saying a change in magnetic field had no impact for us, I'm just in doubt that space would drop on earth if we'd loose the field; Not to say I'm sure that wouldn't happen then.) – Zaibis Jul 21 '17 at 9:48
• Humans may have survived the last geomagnetic reversal; and life in general has survived several. It will certainly have no effect on the human heart or any other human organs. (The Earth's magnetic field is orders of magnitude weaker than a fridge magnet, and those are not known for stopping your heart or brain!) It may affect the navigational abilities of some animals, and electrical storms during the reversal may cause problems for electronics; but it cannot directly harm any living creature. – Graham Jul 21 '17 at 12:32
• @Zaibis as I understand it, the collapse of Earth's magnetic field wouldn't affect material object collisions (the atmosphere would still be just fine). However it would have a huge impact on the shielding of the Earth from solar wind and radiation. The question is, how quickly would the reversal re-stabilize, and how much exposure would we get? – Memetican Jul 23 '17 at 10:00
• @Graham: "may" understates it a bit: the last geomagnetic reversal was 780k years ago, so barring the geologists being completely wrong or Ussher being completely right, humanity survived it :-) Or anyway, Homo erectus did. Homo sapiens survived the Laschamp event, which from the POV of a person on the ground at the time was probably just as harmful as a full reversal. – Steve Jessop Jul 23 '17 at 17:00

One I didn't see mentioned. Global Overpopulation is an eventuality. At some point we will continue to multiply until there is no room to stand or not enough food or clean water for all the inhabitants. This is calculable given current trends. There are factors that will adjust that date, but it is still quantifiable. Sure there are missions to Mars and space colonization, but we are fast approaching the point we won't be able to do that in time. There could be another ice age or a global pandemic that pushes it out further. But once we reach a point, there will be no going back. Who is going to condone mass scale genocide so the rest of us can live? We will see it coming and it will be gruesome. X-(

Projected global population

• Global overpopulation is far from an eventuality, given dropping birth rates and rapidly improving agricultural technologies. Moreover, this would be a slow boil, not a dramatic apocalyptic event that could accidentally be discovered by a few people in advance. That's what he's asking for. – Ariah Jul 22 '17 at 2:38