Question: What are some explicit examples of major mathematical results understandable by an intelligent lay person ?
Here are few I managed to google:
Euclid - infinitude of primes.
Cantor - the real numbers are uncountable.
Question: What are some explicit examples of major mathematical results understandable by an intelligent lay person ?
Here are few I managed to google:
Euclid - infinitude of primes.
Cantor - the real numbers are uncountable.
As in the comment by Yuriy S, trivial is not the word we want to use.
That said, the proof that $\sqrt{2}$ is irrational is easily understandable and had profound implications. It was thought that all numbers could be expressed as the ratio of two integers yet this one could n0t. This is profound because we knew that the diagonal of a unit square has a length equal to $\sqrt{2}$ and yet this number couldn't exist under the assumptions of the day.
This lead to the concept of an irrational number and eventually, the real numbers.