We don't have a fully general method for solving all classes of partial differential equations.
open
Global / Unspecified, Global
These equations describe everything from heat flow to fluid movement, but many types still lack a general, reliable solving method. Progress here would ripple into physics, engineering, and climate modeling.
Citation ID: WS00355
Title: We don't have a fully general method for solving all classes of partial differential equations.
URL: https://worldsolve.org/index.php?api=problem&id=355
We haven't proven the exact conditions under which certain infinite series converge to a finite value.
open
Global / Unspecified, Global
Some mathematical series behave predictably, while others sit in ambiguous territory where convergence is difficult to prove definitively. Fully resolving these cases remains an active area of mathematical research.
Citation ID: WS00354
Title: We haven't proven the exact conditions under which certain infinite series converge to a finite value.
URL: https://worldsolve.org/index.php?api=problem&id=354
We haven't proven a rigorous, complete theory explaining turbulence in fluids mathematically.
open
Global / Unspecified, Global
Turbulent flow, like water rushing through a pipe or air moving over a wing, is notoriously hard to describe with exact mathematics. A complete theory would improve everything from weather prediction to aircraft design.
Citation ID: WS00295
Title: We haven't proven a rigorous, complete theory explaining turbulence in fluids mathematically.
URL: https://worldsolve.org/index.php?api=problem&id=295
We don't have a general formula predicting exactly how many prime numbers exist below any given number.
open
Global / Unspecified, Global
We have very good approximations, but no exact formula exists that perfectly predicts the count of primes below a chosen number. Improving this approximation remains an active and important area of research.
Citation ID: WS00294
Title: We don't have a general formula predicting exactly how many prime numbers exist below any given number.
URL: https://worldsolve.org/index.php?api=problem&id=294
We haven't settled whether every sufficiently large even number can always be written as the sum of two prime numbers.
open
Global / Unspecified, Global
This idea, part of an old and famous conjecture, has held true in every case checked so far but has never been proven true for all numbers without exception.
Citation ID: WS00293
Title: We haven't settled whether every sufficiently large even number can always be written as the sum of two prime numbers.
URL: https://worldsolve.org/index.php?api=problem&id=293
We don't have a complete solution to the traveling salesman problem for very large numbers of locations.
open
Global / Unspecified, Global
Finding the shortest possible route visiting a long list of locations becomes exponentially harder as the list grows, and no fully efficient general solution exists. Logistics, chip design, and delivery networks all run into this limit.
Citation ID: WS00292
Title: We don't have a complete solution to the traveling salesman problem for very large numbers of locations.
URL: https://worldsolve.org/index.php?api=problem&id=292
We haven't proven whether there are infinitely many twin prime numbers.
open
Global / Unspecified, Global
Twin primes are pairs of prime numbers that differ by only two, and mathematicians strongly suspect there are infinitely many, but nobody has proven it. This remains one of number theory's oldest open questions.
Citation ID: WS00291
Title: We haven't proven whether there are infinitely many twin prime numbers.
URL: https://worldsolve.org/index.php?api=problem&id=291
We don't know whether P equals NP, or whether some problems are fundamentally harder to solve than to check.
open
Global / Unspecified, Global
If P equaled NP, countless hard problems in logistics, cryptography, and optimization could be solved efficiently, but most computer scientists suspect they can't. This remains the most famous open question in computer science.
whether
problems
know
equals
some
mathematics-logic
Citation ID: WS01229
Title: We don't know whether P equals NP, or whether some problems are fundamentally harder to solve than to check.
URL: https://worldsolve.org/index.php?api=problem&id=1229
We haven't proven the Riemann Hypothesis, which predicts exactly where the building blocks of prime numbers hide.
open
Global / Unspecified, Global
This conjecture about the zeros of a specific complex function would, if proven, tighten our understanding of how primes are distributed among all integers. It's considered one of the most important unsolved problems in mathematics.
proven
haven
riemann
hypothesis
predicts
mathematics-logic
Citation ID: WS01230
Title: We haven't proven the Riemann Hypothesis, which predicts exactly where the building blocks of prime numbers hide.
URL: https://worldsolve.org/index.php?api=problem&id=1230
We still don't know if every mathematical statement that seems true can eventually be proven within a single consistent system.
open
Global / Unspecified, Global
Gödel's incompleteness theorems already showed some truths escape any fixed formal system, but the full boundary between provable and unprovable truths remains an active area of exploration. This shapes how we understand the limits of formal reasoning itself.
system
know
every
mathematical
statement
mathematics-logic
Citation ID: WS01231
Title: We still don't know if every mathematical statement that seems true can eventually be proven within a single consistent system.
URL: https://worldsolve.org/index.php?api=problem&id=1231
We haven't determined whether the number of solutions to certain simple equations in whole numbers is always finite or sometimes infinite.
open
Global / Unspecified, Global
Many Diophantine equations, which ask for whole-number solutions, resist any general method for predicting how many solutions exist. Solving specific cases has taken decades and earned major mathematical prizes.
solutions
number
equations
whole
haven
mathematics-logic
Citation ID: WS01232
Title: We haven't determined whether the number of solutions to certain simple equations in whole numbers is always finite or sometimes infinite.
URL: https://worldsolve.org/index.php?api=problem&id=1232
We don't know whether every sufficiently large even number can be reached by adding two numbers that are each a prime or one more than a prime.
open
Global / Unspecified, Global
This weaker cousin of Goldbach's Conjecture illustrates how even modest-sounding claims about primes can remain unproven for centuries. It highlights how little we still understand about the raw arithmetic of prime numbers.
prime
numbers
know
whether
every
mathematics-logic
Citation ID: WS01233
Title: We don't know whether every sufficiently large even number can be reached by adding two numbers that are each a prime or one more than a prime.
URL: https://worldsolve.org/index.php?api=problem&id=1233
We still haven't proven whether there are infinitely many prime numbers of the form found in Mersenne's sequence.
open
Global / Unspecified, Global
Mersenne primes, of the form two raised to a power minus one, are the largest primes ever discovered, but no one has proven that the list never ends. Finding new ones remains an active computational hunt.
proven
form
mersenne
haven
whether
mathematics-logic
Citation ID: WS01234
Title: We still haven't proven whether there are infinitely many prime numbers of the form found in Mersenne's sequence.
URL: https://worldsolve.org/index.php?api=problem&id=1234
We haven't resolved whether the digits of pi contain every possible finite sequence of numbers somewhere within them.
open
Global / Unspecified, Global
If pi is what mathematicians call 'normal,' every string of digits, including your birthday or an entire book encoded in numbers, would appear infinitely often. No proof exists either way, despite pi's digits being computed to trillions of places.
digits
every
numbers
haven
resolved
mathematics-logic
Citation ID: WS01235
Title: We haven't resolved whether the digits of pi contain every possible finite sequence of numbers somewhere within them.
URL: https://worldsolve.org/index.php?api=problem&id=1235
We don't know how to efficiently factor extremely large numbers into their prime components.
open
Global / Unspecified, Global
This difficulty is exactly what keeps most modern encryption secure, since multiplying primes together is easy but reversing the process is not. If an efficient method were found, it could upend the security of the internet as we know it.
know
efficiently
factor
extremely
large
mathematics-logic
Citation ID: WS01236
Title: We don't know how to efficiently factor extremely large numbers into their prime components.
URL: https://worldsolve.org/index.php?api=problem&id=1236
We still haven't determined the exact boundary of how densely objects can be packed into higher-dimensional spaces.
open
Global / Unspecified, Global
Sphere-packing problems are solved for a few specific dimensions, but the general pattern across all possible dimensions remains unknown. This affects fields ranging from error-correcting codes to theoretical physics.
haven
determined
exact
boundary
densely
mathematics-logic
Citation ID: WS01237
Title: We still haven't determined the exact boundary of how densely objects can be packed into higher-dimensional spaces.
URL: https://worldsolve.org/index.php?api=problem&id=1237
We haven't proven whether chess, in principle, always has a guaranteed winning or drawing strategy for one side from the starting position.
open
Global / Unspecified, Global
Despite chess being fully deterministic with no hidden information, its complexity is so vast that no one has proven who truly holds the advantage under perfect play. Solving smaller games has offered clues, but full chess remains unresolved.
chess
proven
one
haven
whether
mathematics-logic
Citation ID: WS01238
Title: We haven't proven whether chess, in principle, always has a guaranteed winning or drawing strategy for one side from the starting position.
URL: https://worldsolve.org/index.php?api=problem&id=1238
We don't know whether every knot can be told apart from every other knot using a simple, efficient test.
open
Global / Unspecified, Global
Mathematicians have many tools for distinguishing knots, but no single method works perfectly and efficiently for every possible case. This unsolved problem sits at the heart of the mathematical field of knot theory.
every
knot
know
whether
told
mathematics-logic
Citation ID: WS01239
Title: We don't know whether every knot can be told apart from every other knot using a simple, efficient test.
URL: https://worldsolve.org/index.php?api=problem&id=1239
We still haven't proven the Collatz Conjecture, a strikingly simple rule that seems to always lead back to one.
open
Global / Unspecified, Global
Starting from any positive number and repeatedly applying a basic rule always seems to eventually reach the number one, but no proof confirms this holds for every possible starting point. Its simplicity contrasted with its difficulty has made it famous among mathematicians and hobbyists alike.
rule
seems
always
one
haven
mathematics-logic
Citation ID: WS01240
Title: We still haven't proven the Collatz Conjecture, a strikingly simple rule that seems to always lead back to one.
URL: https://worldsolve.org/index.php?api=problem&id=1240
We haven't resolved how many unit squares are needed, at minimum, to tile a square of a given odd size without overlaps or gaps.
open
Global / Unspecified, Global
Certain simple-sounding tiling and packing puzzles remain surprisingly resistant to a complete general solution. These problems test the limits of combinatorics and geometric reasoning.
haven
resolved
many
unit
squares
mathematics-logic
Citation ID: WS01241
Title: We haven't resolved how many unit squares are needed, at minimum, to tile a square of a given odd size without overlaps or gaps.
URL: https://worldsolve.org/index.php?api=problem&id=1241