One great problem, three kinds of immersion

From a story to your own conjecture

Problem stories open curiosity. The problem workshop is the next place, where curiosity becomes a testable idea.

  1. 1 · DiscoverYou are hereMeet the questionLearn when it appeared and why it still holds people’s attention.
  2. 2 · ChallengeTest one caseMake your first observation in five minutes with a drawing, calculation, or colors.
  3. 3 · DevelopBuild on ideasPublish an observation and grow it through comparisons, conjectures, and counterexamples.
Open1859

Riemann Hypothesis — The Enduring Question in a Six-Page Manuscript

Do all nontrivial zeros of the zeta function have real part one-half? In a six-page manuscript of 1859, Riemann wrote that after a few unsuccessful attempts he had set aside the search for a rigorous proof. The short claim became a vast programme for measuring irregularity among the primes.

Challenge passport
First posed
1859
Time it held mathematicians
167 years open · as of 2026
Starting level
Research frontier

Small experiments are possible, but a complete proof sits at the frontier of modern mathematics.

The starting level measures how easily you can understand and test small cases. It is not the difficulty of a complete proof.

Jump to your first five minutes

Clay Mathematics Institute — $1 million (one of the seven Millennium Problems)

Increase N and watch the zeros sharpen — Riemann sandbox

Explore |ζ_N(½ + it)| through the alternating eta-series approximation. As N grows, residuals shrink at the known true zeros marked by pink dashed lines. Compare sharper approximation with its added computation cost.

0124t=0t=10t=20t=30t=40t=50Known zeros (true ζ)

An approximation of |ζ_N(½ + it)| using the alternating eta series, which converges on the critical line. As N grows, residuals shrink at the pink dashed lines marking known true zeros.

Cutoff N
200
Zeros detected
10 zeros
Mean zero residual
0.0187
Computations
72,000 ops
Notable N

Problem statement

If ζ(s) = 0 and s is a non-trivial zero, then Re(s) = 1/2. The trivial zeros are at negative even integers; the question is whether all others lie on the critical line.

The story of this puzzle

In 1859 Bernhard Riemann published a paper in the Berlin Academy proceedings connecting the count of primes with zeros of the zeta function. Its surviving manuscript is only six pages, yet it shifted attention from the average density of primes to their deviation from that average.

Why it matters: the prime number theorem gives the average trend; the Riemann hypothesis would place a strong bound on the fluctuations around it. A counterexample would not instantly break cryptography or erase number theory, but many conditional bounds would need revision. The Clay Mathematics Institute reports that the first ten trillion zeros have been checked on the critical line. This is powerful evidence, not proof about infinitely many zeros.

A human aside: the atheist G. H. Hardy is said to have mailed a postcard claiming a proof before a stormy boat trip, joking that God would not let him die and leave a false theorem. It is best enjoyed as mathematical humour, not as evidence that the problem destroys minds.

Try it yourself

Mini challenge

Compare finite evidence with proof. Plot |ζ(1/2 + it)| near t ≈ 14.135, 21.022, 25.011, and 30.425 and locate the dips toward zero. What logical gap remains between checking four, a million, or ten trillion cases and proving a claim about every case?

Beyond MathVoyage

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