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Number theory · Concept hubDeep story

Prime Numbers

300 BCE (approx.)Ancient Greece (Euclid)

As numbers grow, do primes fade away—or reveal a hidden order?

Where two intuitions collide

The next prime appears irregularly, yet the density of primes becomes remarkably predictable from afar.

This voyage is an editorial path for understanding, not a claim of direct historical influence or sole invention.

Understand it in one breath

Numbers greater than one divisible only by 1 and themselves — 2, 3, 5, 7, 11, 13, … The multiplicative atoms of the integers. RSA relies on the apparent classical difficulty of factoring large composites, while internet security combines many cryptographic methods, protocols, and implementations.

At a glance

The first 25 prime numbers

2, 3, 5, 7, 11

13, 17, 19, 23, 29

31, 37, 41, 43, 47

53, 59, 61, 67, 71

73, 79, 83, 89, 97

The atoms of the integers, easily found with the Sieve of Eratosthenes.

Concept

Integers greater than 1 divisible only by 1 and themselves — the multiplicative atoms of whole numbers. Euclid proved there are infinitely many; primes also support several, but not all, modern cryptographic systems.

Key formula

pP    p>1    (dp,  d=1d=p)p \in \mathbb{P} \iff p > 1 \;\land\; (\forall d \mid p,\; d = 1 \lor d = p)

Worked examples

  1. 1

    Q.Is 6 prime?

  2. 2

    Q.Is 13 prime?

Ports in time

This concept was not invented in one instant

Follow the scenes to see problems, notation, standards of proof, and applications changing across different times and places.

1
BC 300Scene 1 / 4Continue through the world of this year

Euclid proves there are infinitely many primes

Book IX of the Elements gives an elegant contradiction proof that primes never run out — one of the earliest landmarks of pure mathematics.

No reliable place is given, so time continues without an invented pin

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2
BC 240Scene 2 / 4Alexandria

The sieve of Eratosthenes

A procedure traditionally attributed to Eratosthenes crosses out successive multiples to leave primes. Later evidence preserves the attribution, not an exact ancient implementation identical to modern code.

The recorded place matches a canonical map anchor

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3
AD 1859Scene 3 / 4Continue through the world of this year

The Riemann hypothesis appears

Riemann connected prime distribution to zeros of the zeta function, opening a problem that remains one of the Millennium Prize Problems.

No reliable place is given, so time continues without an invented pin

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4
AD 1977Scene 4 / 4Continue through the world of this year

RSA — primes secure digital communication

Rivest, Shamir, and Adleman created public-key cryptography from the asymmetry between multiplying large primes and factoring their product.

No reliable place is given, so time continues without an invented pin

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Modern applications

RSA and several other constructions use arithmetic built from large primes or finite fields. Internet security also depends on elliptic curves, symmetric ciphers, hashes, protocols, implementations, and key management; primes are important, not the whole system.

Beyond MathVoyage

Curated sources and problems. Bring one discovery back from OEIS, Project Euler, MathOverflow, or arXiv.

No concept belongs to one person

Follow people who played different roles

These are not inventor credits. They are different ports: opening a problem, sharpening a language, or carrying it into another world.

Number lenses

A concept looks different when its world of numbers changes

These numbers are editorial lenses for the voyage, not required prerequisites.

Concept genealogy

What supports it, and what does it open?

Concepts arriving from before

No direct prerequisite port is curated yet.

Current port

Prime Numbers

Only direct editorial links are shown; this is not a complete learning order or historical influence line.