The person credited with discovering (or inventing) the idea of different "levels" or "sizes" of infinity is Georg Cantor.

Cantor developed the theory of transfinite numbers, introducing the concept that some infinities (like the set of real numbers) are larger than others (like the set of natural numbers). This groundbreaking work in set theory revolutionized mathematics and established a deeper understanding of infinity.

Would you like to explore more about Cantor's contributions or the concept of different infinities?

Related Questions:

1. What is the difference between countable and uncountable infinity?
2. How did Georg Cantor's ideas impact modern mathematics?
3. What is the diagonalization argument used to show the difference in sizes of infinities?
4. Are there practical applications of Cantor's set theory in computer science or physics?
5. Who were some of Cantor's contemporaries, and how did they react to his work?

Tip: To understand different sizes of infinity, start by studying the relationship between natural numbers, integers, rational numbers, and real numbers.