Top 10 Unanswered Questions: Mysteries No One Has Solved

Science has explained a lot of things down to the tiniest detail… but some questions still keep spinning around in our heads like endless riddles. These are the kind of mysteries that have been around for centuries — and while we’ve got plenty of theories, we’re still missing solid answers. Why do we dream? What’s beyond the stars? Why do we get that weird empty feeling when someone yawns and we yawn too?
Here are 10 big questions we still can’t answer for sure — but they’ll definitely get you thinking (or at least give you something interesting to drop in a conversation).

1. Why do we really dream?

Dreams are like stepping into a strange movie where anything can happen — you fly, fall, see people who aren’t around anymore, or find yourself in places that don’t exist. But… why do we dream? Some say it’s how the brain processes memories. Others claim it helps release stress or lets us “practice” tough situations. But no single theory fully explains it.

What about lucid dreams? Or those times when you dream about someone you haven’t seen in years? Science keeps digging, but we still don’t have a clear, universal explanation. This one lives somewhere between biology and the spiritual world.

2. Why do we yawn — and why is it contagious?

Yawning is automatic. Most of the time, you can’t help it. But the weird part? Once you see someone else yawn, you probably yawn too. That domino effect is still a mystery. Some researchers say it helps cool down the brain. Others think it’s an old-school form of empathy.

Even dogs have been known to “copy” their owners’ yawns. Something so small and seemingly meaningless still has science scratching its head. Is it social bonding? A glitch in our system? No one really knows.

3. What’s hiding at the bottom of the ocean?

Less than 10% of the ocean has been explored. Seriously — we know more about Mars than about what’s going on deep down on our own planet. Down there, it’s pitch black, freezing cold, and full of bizarre creatures that glow, crawl, or survive without ever seeing sunlight.

Some places are so deep and pressurized that humans can’t go without special submarines. So… what’s down there? Ruins? Alien-like ecosystems? Giant sea monsters? No one can say for sure. And that’s what makes it even more fascinating.

4. What existed before the Big Bang?

Now we’re in mind-blowing territory. The Big Bang is the leading theory for how our universe started. But… what came before it? Was there another universe? Was there absolutely nothing? Another dimension?

Short answer: we don’t know. There are theories about infinite cycles, parallel realities, or a total void. But human brains aren’t great at imagining “nothing,” and that’s when the existential crisis hits. If the universe began at one moment… who pressed start?

5. Why do we experience déjà vu?

That weird moment when everything feels oddly familiar — even though you know it’s your first time living it. Déjà vu is like a mental glitch. Some scientists think it’s a short-term memory hiccup: your brain misfiles the present as a memory. Others say it’s an “echo” from another reality… or linked to dreams.

Could it be proof we’re living in a simulation? Or a hint that time isn’t as straight as we think? Neuroscience is still on the case — but déjà vu keeps being one of those everyday mysteries that makes you question everything for a second.

6. Why do we age?

Seems like a simple question: because that’s just life. But when you think about it… why can’t our bodies stay young forever? Some species live way longer than we do. Others barely seem to age at all.

At the cellular level, we know that cells can only divide a certain number of times before they stop regenerating. But why is that built-in limit there? Is it a flaw? Or a feature? Scientists are working hard to slow aging — but they still don’t fully understand why it happens in the first place.

7. Why does evil exist?

A classic, eternal question. If good, compassion, and empathy exist… why do some people hurt others for pleasure? Some blame biology: instincts, trauma, survival. Others look to society, culture, or even spirituality.

Religions and philosophies have tried to explain the roots of evil for centuries. Is it necessary for balance? A byproduct of free will? One thing’s clear: evil isn’t as black-and-white as “good vs. bad” — and we still don’t have a one-size-fits-all answer.

8. Are we alone in the universe?

Probably the biggest question of our time. There are billions of planets out there. Could we really be the only ones with consciousness? Science is searching for signals — sounds, radio waves, microbes on Mars — but so far, radio silence.

What if alien life is nothing like we imagine? What if they’ve already come and gone? Or worse… what if civilizations always destroy themselves before they can connect? This one’s wide open — and more than a little unsettling.

9. What really happens when we die?

The one thing we’re all guaranteed — and the one thing we still can’t fully explain. Do we shut off like a light switch? Go to another realm? Get reincarnated? Depends on who you ask — science, religion, and personal belief all have their say.

We’ve studied near-death experiences, but nothing is 100% conclusive. Death scares us, sure — but it’s also what makes life so precious. And the not-knowing might be part of the point.

10. Why is it so hard to be happy?

We live in the most comfortable era in history — and yet stress, anxiety, and burnout are everywhere. Why is that? Is it about expectations? Constant comparison? The pressure to always feel good?

Happiness seems less like a permanent state and more like a process. But even when we have everything “we need,” something often feels missing. Maybe it’s not a question with one clear answer — and maybe that’s why we keep chasing it.