Humanity has come up with some pretty interesting theories over the years.

Some are definitely more interesting than others.

Some of them are just downright terrifying.


Redditor Comprehensive-Note31 asked:

"What is the scariest theory known to man?"

Dual Consciousness Theory

"The dual consciousness theory disturbed me when I read about it."

"Basically (in my limited, layman understanding), a corpus callosotomy is a procedure that is sometimes used to treat conditions like epilepsy, where the connection between the two halves of the brain is severed."

"People can survive this and continue to live semi normally, but usually with some cognitive impairments. Both halves of the brain continue to be 'alive', but there is little to no communication between the two sides."

"People who undergo the procedure can also exhibit some strange phenomena like alien hand syndrome, where the patient feels like some of their limbs will move on their own accord. They can also have difficulty controlling their non-dominant hand, trouble speaking, and issues with certain parts of their vision."

"The dual consciousness theory posits that both halves of the brain retain a consciousness after this procedure. Essentially, you become two people sharing the same body, completely unaware of each other."

"One variation of the theory is that one half of the brain is dominant, controlling most bodily functions, while the other half is basically cut off from most external stimuli, unable to communicate with the outside world, for their rest of their life."

"Obviously this is only a theory and may not be correct. Also, even with the concerns around the operation I can totally understand parents choosing this for their kids - epilepsy can be a debilitating disease and this could be the only option."

"My sister had epilepsy and thankfully she got over it with medication, but it is brutal. Not everyone who has this operation has the side effects that I described, many of them lead normal lives."

"I'm not disturbed by people who have had this operation, just by the implications the theory could have for consciousness in general."

-anemonegemini

​The Great Filter

"The great filter. The idea that we see no other civilizations out in space because they hit some wall that made them go extinct."

"Whatever it may be, it could be the reason we see no intelligent life out there, the question is, are we past the filter, or is the worst still to come?"

-_Filter

"Good news, then"

"The Great Filter doesn't take into account that the Universe has only been liveable for an EXTREMELY short amount of time, and, in all likelihood, we are one of, if not the very, first advanced civilizations."

"Basically, the Great Filter doesn't say it's impossible for civilizations to get to the Expansionist and Grabby stages, just hard."

"And because it's just hard, that means that if there were advanced civilizations before our own, we would see the Grabby results of them."

"But we don't, which is not a confirmation of the Great Filter, but more an indication that we are very, very, very early in the timeline of this Universe's 'liveable' stage, & for expanding & becoming Grabby ourselves."

"So the Great Filter is more a cautionary hypothesis than it is a death sentence law of nature."

-emillang1000

Cold, Cold Death

"Cold Death of the universe. That the speed at which the universe is expanding is to the point where gravity will never pull it back."

"Matter will spread out and cool down and decay until everything, everywhere, just stops. forever."

-fdsdfg

We'd Never Know

​"The fact that it would take 8 minutes for earth to know that the sun exploded and it could have exploded 7 minutes ago"

-My-name-is-jef56

Proton Decay

"​The theory of proton decay, where every single bit of baryonic matter will eventually just spontaneously dissolve into radiation and fundamental particles, guaranteeing that there will be no survivors at the end of the universe is... yeah terrible"

-KentoKeiHayama

"Genuinely asking here; isn't the impending (but incomprehensibly far in the future) heat death of the universe a fairly widely-shared, well-grounded theory at this point? I'm not sure if the two are actually interchangeable so maybe this is a moot point. I don't know sh*t about sh*t so please feel free to ignore me."

-JamesSFordESQ

"There would still be matter with heat death - just cold and no interaction. The idea though is that, given enough time, it may be that protons decay too. If that is the case, then not only would the heat death occur, there would be no matter, either. From bleak to bleaker, really."

-WolfySpice

Uncanny Valley

"The idea that the Uncanny Valley is because of the ancient hominids we used to interact with during the Pleistocene. Sure, there were interbreeding events, but imagine if you had no idea what a Neanderthal or a Denisovan were and saw one for the first time."

"You and your family have been traveling far from home and seek refuge in a cave for the night. You get a fire going, everyone starts to relax."

"Then out of nowhere, this 'almost human' looking being walks up. You all panic and run. Reacting with fear was probably the easiest way to make it out of an encounter like that alive."

-Bromelia_and_Bismuth

Is It Just Me?

"Solipsism. Basically There's no way to prove that anyone other than yourself actually exists. You can dive deeper if you like its actually pretty interesting."

-CasualBiceps

"My dad's friend believes this. He's essentially seen enough therapists that he just finds it easier to 'go with the illusion'."

"He has a wife. He loves her. He 100% believes she's not real."

"She's aware of this, and for some reason takes him as he is. He's a really nice guy."

"He seems incredibly content. Like if this is what the matrix is giving him, he may as well find joy in it."

-A_Is_For_Azathoth

What Is Consciousness?

​"That our consciousness doesn't actually direct our actions, but just makes up stories to explain our actions to itself. Consciousness might not even be useful to our evolution, it could just be a weird phenomena that came about as our brains became more complex and developed more self-monitoring systems."

-anemonegemini

False Vacuum Decay

False vacuum decay

"In quantum field theory, a false vacuum is a hypothetical vacuum that is stable, but not in the most stable state possible (it is metastable). It may last for a very long time in that state, but could eventually decay to the more stable state, an event known as false vacuum decay."

"The most common suggestion of how such a decay might happen in our universe is called bubble nucleation – if a small region of the universe by chance reached a more stable vacuum, this 'bubble' (also called 'bounce')would spread."

-pradeep23

​We Literally Can't Know

"​What if our understandings of physics and science, what we base out whole lives around, is just wrong. A man born without eyes cannot see, what if we are missing a huge chunk of reality, simply due to an inability to detect it?"

-LucarioKing0

"This seems incredibly likely to me. Our senses evolved for survival, not necessarily for accurate perception of reality."

-fwonkas

Not all theories are scary, but some of these ones are getting into existential dread territory.

Remember, though, they're just theories—not facts.

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