Thank you for visiting this site. This article presents a guided list of the famous unsolved problems of mathematics and science.
âUnsolved problemsâ may conjure discussions meaningful only to specialists. In fact, several of mathematicsâ famous open problems have statements a schoolchild can understand. Can every even number be written as two primes? Does the game of tripling and adding one always come back to 1? The rules are as simple as play â yet the worldâs geniuses have attacked them for centuries, and not one person has produced a proof. That gap, I think, is this genreâs greatest attraction.
Nor are these mere brain-teasers. Some carry a one-million-dollar bounty per problem, and the list includes questions wired straight into modern societyâs foundations â the security of internet encryption, and the limits of what computers can do.
This article organizes the famous unsolved problems into 4 genres and 15 problems: âprimes and integers,â âsimple rules and computation,â âshapes and equations,â and âphysics and the cosmos.â All seven âMillennium Prize Problemsâ â mathematicsâ most important questions, at a million dollars each â are included. Every problem has its own full article.
The Conjectures That Challenge Primes and Integers
The first genre: the unsolved problems of primes and integers, the royalty of mathematics. That the primes 2, 3, 5, 7, 11⊠continue forever has been known for 2,300 years â yet when it comes to their âarrangement,â even modern mathematics has not reached the core. Each problemâs statement fits in a line.
| Problem | In one line |
|---|---|
| The Riemann hypothesis | Do the âzeta zerosâ that govern the primes all lie on one straight line? |
| The Goldbach conjecture | Is every even number from 4 up a sum of two primes? |
| The twin prime conjecture | Are there infinitely many prime pairs differing by 2? |
| Odd perfect numbers | Does an odd number equal to the sum of its divisors exist? |
| The ABC conjecture | A law linking addition and multiplication â its âproofâ divides mathematics |
The Riemann hypothesis has stood unsolved since 1859 â over 160 years; Goldbach, since 1742 â over 280. Computer verification finds Goldbach counterexample-free out to the staggering figure of four quintillion. And still, in the world of mathematics, no pile of examples ever proves âtrue for all numbers.â
The Mysteries of Simple Rules and Computation
The next genre concerns âoperationsâ and âcomputation.â The Collatz conjecture is a bottomless mystery born of a playthingâs rule. P vs NP is a question with computer scienceâs very existence staked on it â and one of the million-dollar Millennium problems.
| Problem | In one line |
|---|---|
| The Collatz conjecture | Does âhalve if even, triple-plus-one if oddâ always return to 1? |
| P vs NP | If an answer is fast to check, is it also fast to find? |
Collatz is the problem that made the genius ErdĆs say âmathematics is not yet ready for such problems.â If P vs NP resolves in the affirmative, much of internet encryption collapses on paper. The gap between innocent appearance and monumental consequence is best savored in the full articles.
The Mysteries of Physics and the Cosmos
The third genre leaps out of mathematics into the real universe itself. Flowing water, orbiting bodies, the contents of the cosmos â all utterly commonplace, all with gaping holes at the center of our understanding. The NavierâStokes problem is a Millennium Prize Problem, with a million dollars of its own.
| Problem | In one line |
|---|---|
| The NavierâStokes equations | The fluid equations carry no guarantee their solutions keep existing |
| The three-body problem | With three bodies, the general solution vanishes and chaos is born |
| Dark matter | The âinvisible somethingâ that is 27% of the universe â identity unknown |
Physical mysteries have a flavor mathematical conjectures lack: the âanswer keyâ can arrive suddenly, by experiment or observation. The chance that tomorrowâs experiment unmasks dark matter or dark energy is not zero â and if it happens, the textbooks are rewritten overnight. YangâMills is a Millennium problem; dark energy is dark matterâs counterpart and the largest mystery in the universe.
| Problem | In one line |
|---|---|
| Dark energy | The unknown force that is 68% of the universe and accelerating its expansion |
| YangâMills and the mass gap | Works in physics, but the mathematical foundation is unfinished |
The Mysteries of Shapes and Equations
The fourth genre: problems abstract yet central to mathematics, hiding deep within shapes and equations. Honestly, this is the seriesâ most technical territory â even catching the atmosphere takes effort. Still, the PoincarĂ© conjecture has the tactile pull of telling the universeâs shape, and BSD offers a surprise entrance through a thousand-year-old right-triangle riddle. All three are Millennium Prize Problems (PoincarĂ© being the lone solved one).
| Problem | In one line |
|---|---|
| The PoincarĂ© conjecture | Telling a universeâs shape by loops. The solver refused honor and money alike |
| The BSD conjecture | Whether an equationâs answers are finite is foretold by a different formula |
| The Hodge conjecture | Said to be the hardest to explain â a bridge between shapes and equations |
All Seven Millennium Prize Problems, Collected
This series has a specialty the other knowledge series lack: prize money.
In 2000, the Clay Mathematics Institute in the United States selected mathematicsâ seven most important problems as the âMillennium Prize Problems,â staking one million dollars on each. This series provides a full article for every one of the seven: the Riemann hypothesis, P vs NP, NavierâStokes, PoincarĂ©, BSD, YangâMills, and Hodge, all introduced above. Of the seven, exactly one is solved â the PoincarĂ© conjecture, proven by the Russian mathematician Perelman. Who then declined the money.
Why does a mathematics institute â not a corporation, not a government â stack up that kind of cash? Because these problems are pressure points where the map of mathematics redraws itself the instant they fall. An unsolved problemâs value lies less in the answer than in the new tools born along the way. Fermatâs Last Theorem took 360 years, falling in 1995 â and the campaignâs by-products became the principal machinery of modern number theory. âThe problems that canât be solved are what move mathematics forwardâ â that paradox is the fun of this genre.
Summary
This article introduced mathematicsâ famous unsolved problems in one guided list.
A one-line problem statement, and no one can solve it. That gap teaches us that humanity still stands at the barest threshold of the world of numbers. Each full article pushes to the frontier of âwhat is known, and what is notâ â start with whichever problem hooked you.
This site also publishes companion collections in the same format: the intuition-defying âlogic and probability puzzlesâ and the âparadoxes of the world.â After tasting the vastness of unsolvable problems, returning to the catharsis of solvable ones is highly recommended.
There are also the âcognitive bias guideâ on the quirks of thinking, and the âthought experimentsâ collection of laboratory-of-the-mind classics â companions for an intellectual pub crawl.
Unsolved mysteries live outside mathematics too. For undeciphered books and vanished people, examined with a fact-checking eye, see the âworld mysteriesâ collection.
Thank you for reading. We hope to see you in the next article.
đ Series: Unsolved Problems in Math & Science (1/16)


















