The 6 Greatest Unsolved Mysteries of the Universe

Science has come a long way, but we still have a lot to learn about the universe, and even ourselves.

The 6 Greatest Unsolved Mysteries of the Universe
Source: Pixabay

Humans have made a staggering amount of scientific and technological progress over the past century.

We’ve created gadgets that have transformed our society; scientific advances have helped us answer fundamental questions about who we are and the world that we inhabit.

And yet, despite all of this development to our collective human knowledge, mysteries still persist.

Our world is shaped by all sorts of unseen forces that we don’t fully understand. Spooky phenomena occurring on every scale from the quantum to the cosmic that we have yet to elucidate.


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People have debated these basic questions of humanity and the universe for decades — sometimes centuries.

Fortunately, our unfaltering will to uncover the world’s mysteries has brought us closer to some of the answers we seek than ever before.

Close… but still with quite a ways to go. On that note, here are six of the biggest as of yet unsolved mysteries of the universe that still keep scientists up at night.

1. Why do we sleep:

The 6 Greatest Unsolved Mysteries of the Universe
Source: Minot Air Force Base

This may seem like a straightforward question, but there have been countless attempts to find a definitive reason as to why humans need to sleep every night, and scientists are still unable to offer a single, definitive answer.

Theories of course abound. The simplest of them is purely that sleep is “energy saving”, based on the fact that nature values inactivity and storing energy for when it is not needed; animals that use a lot of energy are not going to survive.

The problem is, humans are very different from most animals, and our big, complex brains may use sleep differently than other organisms.

Another popular theory is that sleep allows the brain to purge itself of unnecessary information, or in other words: sleep is the price we pay for learning.

The idea here is based on recent research the suggests that sleep allows the strong neural connections we form when learning to become pliable enough to fit in with the rest of the information stored inside our head.


However, while we know that is how long-term memory works, no one has been able to prove that sleep is actually necessary for the process to work.

Whatever the case one thing remains clear: we have to sleep.

Without it, out attention starts to lapse, our intelligence plummets, our body starts to ache, and eventually… we die. If only we had the slightest idea of WHY!

2. Origin of the universe:

You are probably under the impression that we’ve already solved this one, at least to some extent. And you shouldn’t be faulted for thinking that.

Perhaps the best-known proposal as to the beginning of the universe is the Big Bang theory, in which the universe expanded from an extremely hot and dense singularity around 13.8 billion years ago.

But this is often misunderstood; matter didn’t simply explode into being from nothing, the Big Bang happened everywhere in the universe simultaneously—it’s not an explosion in space but an explosion of space.


Yet, the exact process of what caused this (and of course, what was there beforehand) remains unknown.

We are inching closer to piecing together the earliest moments of the universe, but its true origin is still a mystery, and any theories or models of ‘creation’ are incredibly speculative at this point.

While we have some idea of the universe when it was only 300,000 years old, scientists are still speculating about the extreme forces at play during the universe’s first moments.

Like all good mysteries, this seems simple to answer but instead yields more questions that must be solved before we can answer the initial question.

Ultimately, we’re prevented from knowing what happened in the very earliest moments (like, less than 10^-40 seconds) because we don’t fully comprehend the quantum aspects of gravity.

To fully understand the creation of our universe, we will need to have a comprehensive understanding of the laws of physics that govern matter and antimatter.


This is a bit of a problem though, as the Standard Model of particle physics doesn’t actually account for the majority of the matter that the Big Bang produced.

Of course, even if we turn the model on its head and manage to understand the nature of matter and antimatter’s interactions, we still won’t have a final answer to how the universe came into being.

But we will at least be one step closer to understanding it.

3. Why is ASMR a thing:

The 6 Greatest Unsolved Mysteries of the Universe

Let’s go from the universal scale to something more personal. ASMR stands for “autonomous sensory meridian response”.

It’s something you may have heard of recently or even encountered on YouTube: thousands of videos narrated in hushed voices and accompanied by soft sounds recorded on specialized microphones, like massaging a textured piece of fabric or the faint hum of a hair clipper.

For some people, the sound creates the sensation of a scalp massage. Not really just “some people” though, studies suggest as much as 90% of the population experience a relaxing, tingling sensation in the brain when exposed to ASMR.


But why this happens, and why it doesn’t work for everyone, is still completely unknown.

Admittedly, this may not be the “biggest” mystery our species faces, but it is a relatively new development born out of modern technology that has been exceedingly good at avoiding even the most basic understanding of how it works.

We are at the very beginning of unraveling the science behind ASMR.

While past biological studies have shown that functional connectivity—regions of the brain that light up on a fMRI—is different in brains that experience ASMR than in those that don’t, researchers have yet to determine what that actually means.

Theories abound; some have suggested the common video formats create a sense of “non-standard intimacy” that produces unique pleasure for those with strong connections to visual media.

Others say the research points to the idea that ASMR activates brain regions that are used during social bonding and musical frisson (I.E. when good music gives you goosebumps), suggesting that extroverts and the musically inclined may be more likely to feel the effects.


Still, others choose to ignore the “why” of ASMR and instead focus on its potential as a therapeutic on par with meditation and suggest that it can have a huge impact on improving mood and pain symptoms.

Ultimately, wherever the research may lead us, many scientists agree at least that ASMR is a supremely complex and deeply personal phenomenon, and don’t think there will ever be one explanation for it that satisfies everyone.

4. Where is the intelligent alien life:

The 6 Greatest Unsolved Mysteries of the Universe
Source: NASA

The universe is billions of years old and contains trillions of stars surrounded by diverse planetary systems.

Considering the age and sheer vastness of our cosmos, it’s hard to comprehend why we haven’t found other signs of intelligent life, or for that matter, any life at all.

Basic probability indicates that we should have found extraterrestrials by now, so where are they?

Astronomers and physicists have put forth many theories in their attempts to explain.


One theory known as “the great filter” suggests there is a great cataclysmic event or insurmountable evolutionary barrier that stops any civilization from ever advancing to the point of making contact.

Another proposes that perhaps most intelligent life remains hidden because there are consequences to being found that we aren’t yet aware of… though perhaps that is a little too far into the realm of science fiction than reality.

Life as we know it is complicated, but in theory, it should be able to exist wherever water, heat energy, and organic compounds can be found together—which fits the bill for many of the moons and exoplanets we can observe.

But we have yet to find signs of even the most basic microbial life elsewhere in the cosmos, let alone intelligent ones.

Could it be that life is far more unlikely than we ever thought it was? Is Earth really that special? Or, is it simply that our view of what life is is too narrow.

Looking for familiar carbon-based life forms that use water as life support might limit us in our quest to find alien life.

Furthermore, if intelligent life is reaching out to the universe as we are, scientists must be able to fully distinguish alien messages from all the other noise in space — and even that is far from simple.

What if their message is indistinguishable from other frequencies? Or what if their technology is far more or less advanced than our own, meaning the problem is as simple a matter as a mismatched transponder and receiver?

In any case, the search is far from over. In fact, it’s only really just begun.

5. Does a Grand Unified Theory exist:

A “Grand Unified Theory” is the idea that all of the basic universal forces are actually part of the same overall force playing out at different energy levels. Confused? Me too. Let’s go into some background:

The universe experiences four fundamental forces: electromagnetism, the strong nuclear force, the weak nuclear force, and gravity.

Physicists know that if you turn up the energy enough— for example, inside a particle accelerator— three of those forces "unify" and become a single force.

Physicists have unified the electromagnetic and weak nuclear forces, and at higher energies, the same thing should happen with the strong nuclear force and gravity.

But even though theories say that should happen, nature has a funny way of not giving up its secrets without a fight.

No particle accelerator has reached energies high enough to unify the strong force with electromagnetism and the weak force, let alone with gravity.

It isn't clear whether scientists could even build one that powerful; the Large Hadron Collider can send particles crashing into each other with energies in the trillions of electron volts, but to reach grand unification energies, particles would need at least a trillion times as much as that!

Besides the issue of energies, Grand Unified Theories are also plagued by predicting certain observations that so far haven't panned out.

There are several promising theories that say protons, over immense spans of time, should turn into other particles. But this has never been observed, so either protons last much longer than anyone thought or they really are stable forever.

Another prediction some theories point to is the existence of magnetic monopoles—"north" or "south" poles of a magnet isolated from the other— but nobody has seen one of those, either.

It's possible we just don't have a powerful enough particle accelerator… or maybe that we are completely wrong about how the universe works. 

6. Dark Matter:

The 6 Greatest Unsolved Mysteries of the Universe
Source: Pixabay

We don’t know what it looks like. We can’t see it. But it makes up more than 26 percent of the matter in the known universe.

We have come to know it exists because of how it interacts with the matter we can observe, but dark matter is still mysteriously invisible to us. (As is its theoretically much more abundant cousin, Dark Energy… a subject for another article.)

Most of the matter that’s visible to us is made of neutrons, protons, and electrons. But dark matter—somehow—is not.

It’s made up of different types of particles we haven’t yet been able to categorize and that interact with light and matter in a completely different way.

Dark matter does not absorb, reflect, or emit light, hence its “dark”-ness, but its gravitational influence does bend light as it passes nearby, which is the only reason we can be sure it exists.

Researchers have been studying this phenomenon, trying to unravel its mysteries, almost since it was first hypothesized in 1922 with relatively little success.

More recently, the Large Hadron Collider at CERN has brought us closer to actually doing so. Additionally, recent advancements in gravitational wave detectors could allow us to “see” dark matter for the first time.

But the truth of the matter—or rather, the DARK matter—is that we still have no clue whatsoever about the makeup of one of the most abundant entities in our universe.

If we can’t even figure that out, just imagine all of the mysteries we haven’t even discovered yet…