1. The human form of mad cow disease may cause thousands of deaths

“vCJD, the human form of mad cow disease, may have a decades long incubation period and cause thousands of deaths in the future.

In cattle the incubation period can be up to 5 years but we have no idea whether or not it could be longer in humans, and there’s no routine method to detect the prion which causes it. Almost half a million infected cows entered the food chain but only a few hundred cases have been reported. Essentially anyone who ate British beef in the 90s could be at risk of a horrible death, with no way to predict or prevent it.” — buttwarm

2. People with split brains exist — and don’t even realize it

“You can split a person’s brain down the middle, entirely severing the connection between the hemispheres. By showing things to different parts of the visual field, you can give information to the hemispheres separately – so one hemisphere can know things that the other does not. As far as we can tell, both hemispheres are conscious beings with hopes and dreams. Usually one hemisphere can’t speak, but from non-verbal indications we can clearly see it has a very human level intelligence. Other times, both hemispheres can speak.

Split brain patients don’t notice nor particularly care that they are split brained. Neither hemisphere seems perturbed by the separation. Verbally, split brain patients say they can’t even tell. And, as far as we can tell, it’s not like the non-verbal hemisphere is screaming quietly or anything. The splitting process just… doesn’t seem to impact people very much, although I did see some reports of people’s left hands doing actions that their verbal hemisphere didn’t seem to agree with. (Unbuttoning shirts they didn’t like, etc)

What does it mean, that we can cut our minds in half and not even notice? What does that mean about our everyday existence? What does that mean of our perception of ourselves as a coherent consciousness? Do we really communicate so little with ourselves that we wouldn’t feel the sudden separation of half of us? What else about ourselves might we not even notice? On the other hand, I guess it’s also kind of inspiring that somehow, everything still more or less works!” — ishaan123

3. One eruption could kill thousands of people

“How Yellowstone National Park is a super volcano that could potentially wipe out a huge chunk of the United States in one eruption.” — Sh3pWr3ck3d

4. A particle the size of a helium atom could end life as we know it at any second

“A strangelet is a hypothetical particle that is composed of up, down, and strange quarks. (For comparison, a proton is composed of two up quarks and a down quark, and a neutron is composed of an up quark and two down quarks.) Some physicists have theorized that strange matter – matter which is made up of strangelets – might actually be what composes dark matter. If that’s true, then 85% of the matter in the universe could be strange matter.

On its own, the theory just sounds mildly interesting.

In fact, it’s utterly terrifying in its implications.

See, due to the way that subatomic particles interact, large collections of strange matter are thought to be more stable than smaller ones. The bigger a given strange mass is, the hardier it is, so to speak. As such, all it would take to completely doom the planet is a strangelet the size of a helium atom… because when baryonic matter – atoms made up of protons and neutrons – comes into contact with strange matter, it gets converted into strange matter. The chain reaction would reduce the Earth to a huge, hot, homogeneous “strange star,” and there would be absolutely nothing we could do about it.

It gets worse, though.

Remember how I mentioned some physicists theorize that strange matter makes up dark matter?

Well, have you heard of The Great Attractor?

This is a region of space that seems to contain an unfathomably large mass, which is pulling all of the galaxies around us – including our own – toward it. We have very little idea what it actually is, but we can see its effects. There are numerous theories on the anomaly, with some being a little bit more reasonable than others. (Don’t say “Cthulhu.”) One idea that’s popular with laymen, however, is that The Great Attractor is composed entirely of dark matter… or as we discussed earlier, strange matter.

In other words, it might only be a matter of time before the entire universe is converted.

Wouldn’t that be strange?” — RamsesThePigeon

5. The Fermi Paradox is absolutely horrifying

“Fermi, anthill highway: ant hill in the middle of a forest and right next to that ant hill we are building a highway, would the ants be able to understand what a highway is? Probably not. So if there was life out there somewhere it could be that they are so advanced we would never understand what they are trying to do, meaning they would never stop to make contact.” — Skeletonman420

6. Dying of Huntington’s disease is beyond painful

“Huntington’s disease is a degenerative disorder of the central nervous system. Think Alzheimer’s but way worse. It’s basically a genetic disorder that causes rapidly progressing dementia. It usually presents after age 50. This is after childbearing age, so it’s basically immune to natural selection against it. It usually runs in families, but doesn’t have to. Anyone reading this could have it and not realize.

Dying of Hintington’s or similar diseases is also miserable. The parts of the brain controlling vital bodily functions are eventually destroyed, but only after your personality and memories. People asphyxiate because they forget how to breathe.” — bunks_things

7. A solar superflare would destroy the ozone layer

“Solar Superflares…

basically, it is a huge solar flare that probably hasn’t happened in our Solar System. But we have observed stars that have weaker magnetic fields than the Sun that exhibit superflares. The largest solar flare that we have recorded was the carrington event. It happened in 1859 and was so strong, it could be seen with the naked eye and even set telegraph systems on fire.

That was only 1/10,000 the energy of the largest known superflares. If one were to happen, the effects are pretty grim.

• airline passengers would receive high-doses of radiation

• all satellites would be damaged, but probably broken

• the ozone layer would be fucked

• loss of most radio communications
• and for a strong one, the Sun’s luminosity increase could cause ice to melt as far as the moons of Jupiter.” — intersecting_lines

8. Astroids hit the planet a lot more than you realize

“Many people don’t realize how relatively common asteroids entering our atmosphere are. I’m talking about 0.1 – 1000’s of kiloton explosions. Dozens each year. Most explode high up in the atmosphere and are harmless. Some explode a bit lower and shatter windows (remember Chelyabinsk)

And once in a while there is an event like the Tunguska event which leveled 2000 km² of forest.

Imagine something like that happening in a modern metropole.

And we have no way of stopping it.” — Bananedraad

9. The cold death of the universe is spooky

“Cold death of the universe theory always spooks me.

It’s the idea that the universe will eventually expand so far that it will become too cold to support life it’ll just kinda go dark.

It’s eerie and depressing.” — Monochrome_Cosmonaut

10. There might be a comet about to collide with Earth that we cannot see

“We can usually only see comets when they are inside of the frost line (roughly the asteroid belt) because they are bright and begin to sublimate and a tail is produced. Comets have very eccentric orbits, so they spend a majority of the time outside of the frost line, and out of our view. Since they are so difficult to detect, we have only found around a couple thousand of them. There are most likely hundreds of millions if not billions of comets in our solar system. It is very possible that there is a comet on a collision course with Earth, and we would not be able to see it until it crosses the frost line. By then, it would be about 6 months out from impacting us. There is absolutely nothing we could do to stop it in 6 months. Also since comets have very eccentric orbits, their relative velocity to Earth is much higher than an asteroid, so it would cause much more damage. I’m talking global climate change and possible extinction of our species. A comet impact would be vastly more devastating than the impact that wiped out the dinosaurs.” — OsamaBinLolling

11. There is a theory about Quantum Suicide

“Quantum Suicide/Quantum Immortality. The idea that we never really die in our perspective. Every time we encounter a situation where we may die, we continue on in a parallel universe where something happens that prevents our death. But we die in the original universe. In a sense, our consciousness lives on by transferring itself to a parallel universe where we continue to exist.” — BarbaraCripps

12. If the universe is under a false vacuum, we could be in trouble

“It has been hypothesized that our universe is under a false vacuum, meaning that zero energy isn’t actually zero energy, the whole universe could go lower, but for some reason it isn’t, like a marble on the second last step. If something nudges it off at any point in space, the laws of physics there completely change as the university rearranges itself fundamentally. This knocks the adjacent space down with it. The resulting chain reaction completely resets the universe, it happens at the speed of light, and we can’t do anything about it.” — Tethalamin

13. One machine could cause all of our deaths

“Grey goo.

This is somewhat similar to the strange matter mentioned elsewhere in the thread, but technological. A microscopic machine that is programmed to break down matter and reorganize it into copies of itself. A sufficiently advanced machine could replicate itself from common materials and multiply at an exponential rate. A single machine could begin to multiply exponentially, consuming all useful matter around it, until the entire crust of a planet is either converted into machines or piled into heaps of useless waste products.

This could happen accidentally. A scientist in the future could make a nanobot with a nasty software bug. A hostile alien race could use it to wipe out human civilization safely and quickly. Maybe this catastrophe has befallen other planets, and the nano machines are able to spread from planet to planet, being plucked from the upper atmosphere by solar wind, destroying everything wherever they make planetfall. Given enough time, goo could travel interstellar or even intergalactic distances.

And all it takes is one to doom every living thing on the planet.” — bunks_things

14. We could all be part of a simulation

“That our universe is just a simulation that has been left on overnight and sometime we’ll just be switched off.” — HitchikersPie

15. The calthrate gun hypothesis is pretty scary

“Once calthrate rock starts releasing methane, global warming becomes as unstoppable and irreversible as a bullet fired from a gun. Some theorize based on geological historical data it causes global extinction in the space of a single human lifetime.

You remember those massive holes in the ground in siberia that turned out to be methane vents? The methane gasing up from the arctic ocean which led a climatonolist to literally say we’re fucked? and the melting permafrost also releasing a bunch of methane as well as ancient diseases?

yeah. We’re in fucking trouble guys.” — usernumber36

16. A sound could kill us all

“A sound with a volume of over 1100 decibels will form a black hole larger than the observable universe. Although it’s unlikely considering the scale is logarithmic, boy that’s spooky.” — Smiis

17. The many worlds theory means there are unlimited parallel universes

“The many world’s theory. Basically whenever something happens, whatever happened stays in this world, but at that moment another time line is made where that thing didn’t happen. So with that theory, there is basically an infinite amount of parallel universes.” — shoodpawoop9900

18. You aren’t actually touching the things you feel

“Everything is 99.999999999%* nothing.

That couch you’re laying down on that you can physically ‘feel’ is actually not touching you at all. What you’re feeling is the magnetic repulsion of the electrons, naturally they’re all negative and same sign magnets repel.

If you were to truly touch something you’d set off an atomic explosion.” — OMA_

19. Some scientists believe in the universe collusion theory

“That one where the world is going to end by smashing into a mirror of itself. So the last thing you see before your die will be your own terrified face.” — cold_toast_n_butter

21. Aliens might be avoiding us on purpose

“One theory as to why we haven’t made contact with aliens is because they fear some other dominant alien species. Essentially, no one wants to challenge the dominant species by furthering themselves because they would risk getting wiped out. Right now aliens could be telling us to shut up while this oh so powerful species is getting ready to annihilate us.” — romeo_the_wolf

22. Generic engineering could cause a silent plague

“Genetic engineering now is getting good. Like, really good. CRISPR is a new technique that is a great way to edit the DNA of microorganisms. Scientists can breed bacteria to produce certain useful substances, like antibodies or insulin. They can also theoretically produce viruses that could edit the DNA of human cells. Imagine an out of control infectious agent that changes our DNA in unpredictable ways. Basically super cancer. There are dozens of other ethical problems, from designer babies to socio-economics.

Also, rememeber Mendel and his pea plants and squares? Well, genetics don’t quite work that way. There are ways to favor a certain trait over another when reproducing, and scientists are figuring out how to do it. There’s already discussion about introducing a gene into African mosquitoes that will eventually render the whole population sterile and, inevitably, extinct. Some bioengineers figure that they can irradiate mosquitoes within five years of initial introduction.

That’s great, right? No more malaria or west Nile.

But what if someone did the same to us?

Program a gene into a virus, infect some poor unsuspecting fellow changing his DNA, and allow it to spread like a silent plague. It won’t take that many generations for most of humanity to be infected. Nigh unstoppable genocide.” — bunks_things

23. There is a philosophy called Determinism

“This is more a philosophical theory than scientific, but well… Determinism.

What if every single decision you and everyone else ever made was exclusively the result of the chemical reactions inside your head/around you.

Personality? Choice? Free will? Illusions, my friend, everything is decided by the atoms, and we have no control at all. If determinism is true, the future is set in stone, and our conscience is but an unintentional side effect of the atoms that compose us doing their tasks.” — SephyJR

24. There are reversible forms of psychosis

“Some people in psych hospitals may have a reversible form of psychosis ( like from autoimmune encephalitis).

Should clarify. Autoimmune encephalitis like your body’s immune system attacking your brain and some cases cause just psychosis. So patients are taken to psychiatric hospitals and put on antipsychotic medications. But actually need different types of medication to return basically back to normal functioning (non psychotic) person.” — lolcatloljk

25. In the future, no one will know about different galaxies

“Hubble’s Law: Simple really, our universe is expanding every second, and with that the galaxies within our universe are (generally) moving relative to this expansion. Meaning, over an inconceivable amount of time, galaxies will be so incredibly far away from each other that the existence of other galaxies will be unknown to any other future intelligent life forms. In other words, if we (humans) instead existed in a time and place extremely far ahead in the future, where the expansion is already present, we would have no evidence showing us that different galaxies even exist; our galaxy would instead be our universe.” — TheMillionthSam

Holly Riordan is the author of
Severe(d), A Creepy Poetry Collection.
Pre-order your copy here.