For the first time in more than 25 years, mathematicians have proven a new way to identify prime numbers, and in doing so developed a toolkit that could allow further advances in number theory.

Prime numbers, which can only be divided by themselves or one, are the mathematical building blocks of whole numbers, and mathematicians have explored how they can be found and combined for hundreds of years. “New results about primes don’t come along that often, so whenever we get some new development, it feels worthwhile,” says Benjamin Green…