Biggest Mysteries of the Universe

To start 2025, I’m going big. I’m consolidating the biggest mysteries of the universe into a blog post! These five top biggest mysteries in science remain unanswered science questions to date.

BIGGEST MYSTERIES OF THE UNIVERSE

Louie next to a mammoth
Size of Louie compared to mammoth

Louie thinks we should talk about using CRISPR to resurrect a mammoth. (For more on what CRISPR is, here’s a great resource)

While CRISPR is cool & amazing with fantastic potential applications to help man, & scientists reconstructed the 3D structure of all 28 of the mammoth’s chromosomes, that no longer qualifies as one of the top biggest mysteries in science.

Plus, I’m surprised that Louie wants to talk about mammoths, considering how large they are.

I have a topic that does qualify as one of the biggest mysteries of the universe.

Dark Matter & Dark Energy. What the heck are they?

Dark matter and dark energy are unsolved mysteries in science.

UNSOLVED MYSTERIES IN SCIENCE : DARK MATTER AND DARK ENERGY

Everything we can observe in the universe, from people to planets, is made of matter. “dark matter’ has matter in its name. 

What is matter?

Matter is defined as any substance that has mass and occupies space.

 

Ian with sunglasses
So we can see dark matter, even with sunglasses on?

Well, no.

We call it ​dark” because we can’t see it.

Like ordinary matter, dark matter takes up space and holds mass. But it doesn’t reflect, absorb, or radiate light – at least not enough for us to detect yet.

Dark matter only interacts interacts with other matter through gravity. 

We know where it should be, but nothing is there when we look. It’s like seeing ripples in a pond, but not being able to see what caused them.

There’s more to the universe than the matter we can see. This is why dark matter and dark energy qualify as unsolved mysteries in science. 

It wasn't until the 1970s that astronomer Vera Rubin confirmed the existence of dark matter
Vera Rubin biography
She studied how galaxies rotate.
She & her colleagues found that individual galaxies may contain invisible mass made of dark matter.
virtual googles
I'll try these and maybe I can see dark matter!

Obviously, that isn’t going to work. 

Dark matter and dark energy are puzzling substances that affect and shape the cosmos. Scientists are still trying to figure them out!

According to NASA scientists, normal matter comprises less than 5% of the total universe!

Scientists have measured that dark matter makes up about 27% of the cosmos....

But they’re not sure what dark matter even is!

Dark Matter for kids

As of the writing on this post, scientists speculate that dark matter exists in a vast, web-like structure that winds through the whole universe – a gravitational scaffold that attracts most of the cosmos’ normal matter.

That sounds more like a spider’s web to me.

No wonder dark matter remains an unanswered science question!

They’ve determined that dark matter isn’t composed of known particles of matter because the universe would look very different if it were. The search for what makes up dark matter continues and qualifies as one of the biggest mysteries of the universe.

pie chart of matter in the universe
courtesy NASA
people at conference with whiteboard
WHAT A MINUTE! That pie chart has dark energy on it!

Yes! I’m getting to that.

Dark energy may compose roughly 68% of the universe, but scientists know even less about it than they do about dark matter.

We can wrap dark energy up with dark matter as one of the top biggest mysteries in science.

Scientist's theorize that something like dark energy must exist to explain the universe’s accelerating expansion
Expansion of the universe
In the 1920's astronomer Edwin Hubble & others discovered that the Universe is expanding.
Hubble Expansion
They showed that most galaxies are receding from our Milky Way
and the farther away they are, the faster they are receding.
In the 1990s, observations of distant star explosions- supernovae-showed that the universe expanded more slowly in the past than it does now.
The leading explanation is that the universe contains something that has a repulsive gravitational effect

This 'something' pushes the universe apart instead of pulling it back together.

This phenomenon is called dark energy.

alex and a whiteboard
Way to make sense of one of the greatest unsolved mysteries of the universe
men at breakfast tables.
You make it so easy, Sue!

Where did this energy come from? And how did matter become life?

Unsolved mysteries in science_Louie the boxer sitting
GREAT QUESTIONS

The origin of life on Earth stands as one of the biggest mysteries of the universe.

The origin of life on Earth ranks as one of the biggest mysteries of the universe

I did a deep dive into theories and came up with my own conclusion.

Scientists are clueless.

Okay, that’s a little harsh. But this is why the origin of life ranks as one of our still unanswered science questions.

And in the interest of trying to dip a toe into the mystery waters, various answers have been proposed, all of which remain unverified. 

To find out if we are alone in the galaxy, we will need to better understand what geochemical conditions nurtured the first life forms.

To summarize:

pool of potential life blossoming
Geothermal pool

The great unanswered science question about the origin of life is :

How did non-living chemical compounds transition into self-replicating, living organisms?

Today, life covers every inch of the planet, from the highest mountains to the deepest sea. How did our planet’s barren rocks, sand, and chemicals give rise to life?

EArth viewed from space
One key question that needs answering is how complex essential molecules like RNA & DNA first formed from simpler compounds.
Another mystery is how these molecules then organized into the first primitive cells.
Despite many theories & experiments, the exact sequence of events and conditions that sparked life on Earth remains unknown.
Because life arose in the largely unknown surface conditions of Earth’s early history, answering these and other questions remains a challenge.

Scientists disagree about which chemical components of life came first, which of life’s processes came first, and where on Earth life first arose.

Even the timing of life on earth is an unanswered science question.

Earth is about 4.5 billion years old. The oldest known fossils, however, are only 3.7 billion years old. So all we know for sure is that something happened during that 600-million-year window!

family members
Logical conclusion!
Most theories assume that cells are too complex to have formed all at once
So life must have started with just one component that survived and somehow created the others around it.
When put into practice in the lab, however, these ideas don’t produce anything particularly lifelike.
It is, some researchers are starting to realize, like trying to build a car by making a chassis and hoping wheels and an engine will spontaneously appear.

A few origin of life theories that do not yet solve this greatest unsolved mystery of the universe

Life emerged from a primordial soup
Odds of getting a functional protein of modest length (150 amino acids) by drawing a compound of that size from a prebiotic soup is no better than 1 in 10164.
Absurd primordial soup
Life on Earth was seeded by comets or meteors
meteorites do contain diverse soluble organic compounds
Life from comets
RNA World Theory
States that evolution of living systems was composed entirely of RNA
RNA world theory
Blob Theory
Tiny specks called biomolecular condensates are leading to a new understanding of the cell
Blob, uh, biomolecular condensate theory
These little blobs inside living cells now appear to feature across all domains of the living world and are connected to just about every aspect of cellular function.
Metabolism First
Ugh.
metbolism first debunked

Biomolecular condensates are the subject of intense interest in cell biology right now.

Not one of these ideas has gained widespread acceptance…yet. How can we know? There is no concrete evidence.

We weren’t even there!

boys outside being silly Science Blog Susan Berk Koch
Maybe we were there!

Let’s move away from the vast unsolved mysteries of the universe yet stay with our top biggest mysteries in science, while focusing on …us!

people at the pier with Louie
GO US!

The ‘Hard Problem’ of Consciousness

One of the intriguing and biggest mysteries of the universe is the problem of explaining the connection between the phenomena of subjective reality & brain processes.

This is called the “Hard Problem of Consciousness.”

Mindfulness based cognitive therapy _lotus flower

We can define consciousness, or the nature of being aware. What consciousness is, how it arises, and why it exists, remains one of the most profound unsolved mysteries in science.

Louie wants me to add that this subjective experience is probably not limited to humans.

 

He’s correct. The evidence from neurobiology & behavior of animals and the famous mirror test implies that animals are aware of themselves.

Louie is not an angry bird
Of course I'm aware. Who cares about a mirror test.
Consciousness is a fundamentally important neurological capacity which is also of great relevance to ethical thinking and decision-making.
Studying conciousness
The scientific basis of consciousness, & the philosophical questions raised by scientific discoveries about consciousness, have attracted intense interest over recent decades.
In humans, conscious perception & cognition relies upon the thalamocortical complex, which supports perception, explicit cognition, memory, language, planning, &strategic control.
Thalamus a& cortex
When parts of the thalamocortical circuitry is damaged or stimulated, corresponding effects are found on conscious contents & state, as assessed by reliable reports.
Damage of TC
Brain diagram of thalamus and cortical pathways
Thalamocortical circuits
Despite advances in neuroscience & cognitive psychology, the unanswered science question of how subjective experiences emerge from the complex interactions of neurons in the brain remains.

Let’s stay with the human brain.

I find the placebo effect a puzzling phenomenon & to date, remains one of the unsolved mysteries in science.

Don’t stop reading, but below are a few scientifically proven articles to improve your brain health! (Plus I wanted to try this widget out…) 

how to keep your brain in shape : Read!

THE PLACEBO EFFECT

The placebo effect is a well-documented phenomenon and is defined as :

Improvement in the condition of a patient that occurs in response to treatment but cannot be considered due to the specific treatment used.

Patients experience real improvements in their health after receiving a treatment with no active ingredients, simply because they believe the treatment is effective.

Placebos actually change a patient’s brain chemistry!

kevin sue Ange at table smiling
That's amazing!
Reseachers believe there are a myriad of placebo effects
Today, the study of the placebo effect can be viewed as a melting pot of concepts and ideas for neuroscience.
Placebos & brain chemistry
Brain mechanisms of expectation, anxiety, & reward are all involved, as well as a variety of learning phenomena.
Neurobiological mechanisms of the placebo effect
The placebo effect sparked a revolution to try to understand one of the top biggest mysteries in science: the mind’s role in healing.
Mind and healing

My initial query on a science article website brought 110,430 results!

 

 I did not read 100K articles, but after several, it is clear that our mind’s role in healing aka the placebo effect remains one of the greatest unsolved mysteries of the universe.  

Dessert on a big screen w Alex
Maybe we should unravel why dessert is so delicious

Desserts? That mystery has been solved!

Unraveling this top biggest mystery in science means deciphering the complex interplay between psychology, biology, biochemistry, & the power of belief.

Doing so could have profound implications for medicine and healthcare.

Within the realms of the fascinating psychological phenomenon called the placebo effect lies its darker counterpart.

The nocebo effect.

 

Louie close up
Do you mean those little bugs on the beach?

THE NOCEBO EFFECT

No, Louie. But the nocebo effect is just as vexing.

The placebo effect occurs when a substance that isn’t actual medicine makes you feel better or improves your symptoms.

The nocebo effect, on the other hand, happens when a placebo makes you feel worse.

Just as the mind can convince the body of positive outcomes with a mere placebo, it also has the capacity to evoke negative consequences through a phenomenon known as the “nocebo effect.”
This intriguing and somewhat ominous aspect of the mind-body connection is now the focus of psychologists seeking to unravel this unsolved science mystery
Nocebo effect
The underlying mechanisms of the nocebo effect are, on one hand, psychological (conditioning and negative expectations) and, on the other hand, neurobiological (role of cholecystokinin, endogenous opioids and dopamine)
nocebo effect's negative role
Nocebo effects can be triggered by verbal suggestions, prior negative experiences, observation of others experiencing negative outcomes, and other contextual & environmental factors.

Experts are looking at the nocebo effect and placebo effect to better understand how positive or negative thinking can impact a person’s physical health. Wrapped together, they remain among the top biggest mysteries in science.

The last of the unanswered science questions in this post today is the enigma of time.

REsidents in didactics in front of a whiteboard
Time is flying because this topic is amazing!

THE ENIGMA OF TIME

Time is an interesting concept that we don’t completely understand. One of the most fascinating aspects of time is time dilation, which occurs when time passes at different rates in different places.

Kevin making a face
No way!

Yes, way!

Time dilation is the slowing of time as perceived by one observer compared with another. This is dependent on the observers’ relative motion or positions in a gravitational field.
Sir Isaac Newton thought time was constant.
He gave us the idea of a "clockwork universe", in which it would be possible to know not only all the past but the future if only we could say where every particle was, in what direction each particle was moving and at what speed.
This model assumed, not unreasonably, that time flows at an ever-constant rate.
But Issac Newton was wrong.
alex holding a stick
Time? It's time to vacuum!

Who was correct about time not being a constant?

Mindfulness based cognitive therapy_Louie blackboard
I was correct!
Perhaps you were correct about time not being a constant, Louie!
But in 1905, Albert Einstein beat you to it.
Special Relativity Theory
Space-Time
Time is not a single constantly flowing entity, but part of a much more complex system, linked with space itself.
Because space and time are part of the same entity it's impossible to move in space without moving in time.
Simply put, moving clocks run slower
One of the most startling consequences of special relativity is that any moving clock slows down relative to a stationary observer.
The portrayal of time dilation was fairly accurate in the sci fi movie Interstellar.
Interstellar movie

FUN FACT:

Astronauts who have spent extended periods in space have experienced time dilation!
They return to Earth slightly younger (okay milliseconds but still younger!) than they would have been if they had stayed on Earth

Another enigma of time, making it one of the biggest mysteries in the universe, is that it only goes forwards, not backwards!

people doing headstands
We can go forwards, backwards, & upsidedown. We must not be time.
The arrow of time, refers to the direction in which time flows
Time only seems to move forward, which is why we remember the past but not the future.
Arrow of time
Certain events in the real world always happen in the same order
Example: you can turn an egg into an omelet, but not an omelet into an egg.
The principle underlying irreversible processes is summed up in the second law of thermodynamics: the entropy of an isolated system either remains constant or increases with time
2nd law of thermodynamics
But....
In classical mechanics & most other branches of physics, the laws are time-reversible, meaning that they remain valid when time is reversed.
The distinction between the fixedness of the past & the malleability of the future is nowhere to be found in the known laws of physics.
The relationship between entropy & time’s asymmetry becomes even more intriguing when considering quantum mechanics.
Shrodinger's Cat
Meaning that we still don’t have a final answer to this unanswered science question for why the universe exhibits such a profound asymmetry in time.

In summary, this is an unanswered science question : why does the universe exhibit such a profound asymmetry in time.

Dali clocks
courtesy Alex Koch, Esq.

There you have it : Five of the biggest mysteries of the universe. 

Which of these five unsolved science questions do you think will be solved first? Which one do you think will never be solved?

 

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Alyssa
Alyssa
January 26, 2025 8:17 am

I don’t think they’ll ever figure out how life began. Even if it’s from comets, where did THAT life begin? It sounds impossible, and cool. Thanks for a great post. You consolidated a lot of info here.

Ami
Ami
January 26, 2025 8:22 am

I doubt they’ll ever really know how our minds can affect our physiology. But I find it endlessly amazing what our minds can do so I wish they’d figure it out. Great post, thanks, Sue and Louie.

Eileen
Eileen
January 27, 2025 8:47 am

So much fascinating stuff here! “Another enigma of time, making it one of the biggest mysteries in the universe, is that it only goes forwards, not backwards!” Unless you write time travel stories.. 🙂 Thanks for a great mind-expanding post!

Unwanted Life
January 28, 2025 5:08 am

A string of chemicals going from not being alive to being alive is one of the hardest things for everyday people to wrap their heads around. It also reminds me of the issue of whether viruses are alive or not. What exactly is life?

Fadima Mooneira
Fadima Mooneira
January 28, 2025 8:56 am

There’s always new discovery every year, every decades. These mysteries made the world around us interesting. Thank you for sharing.

Savannah
Savannah
January 28, 2025 1:24 pm

Great post! This was a fun read and covered SO much ground, and I loved getting sucked into theories and ideas. I also learned about the nocebo effect—so interesting! Thank you for sharing.

Susan Berk Koch author

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