ELI5: Explain Like I'm 5

Cantor's paradox

Imagine you had a toy box with different kinds of blocks. Let's say you have some red blocks, blue blocks, and green blocks. You count them and you have three of each color, so there are 9 blocks in total.

Now, let's say you wanted to check if there were more red blocks or blocks in total. To do this, you would need to count how many red blocks there are and how many blocks there are in total.

But what if you had an infinite number of blocks and colors? It would be impossible to count every block and every color. This is where Cantor's Paradox comes in.

Cantor's Paradox is a mathematical idea that shows how trying to count infinite sets can lead to strange and unexpected results.

To understand Cantor's Paradox, pretend you have an infinite set of whole numbers, like 1, 2, 3, 4, 5... and so on. This is an infinite set because you can keep counting higher and higher numbers without ever reaching the end.

Now imagine you have another infinite set that only contains even numbers, like 2, 4, 6, 8... and so on. This set is also infinite because you can keep counting higher and higher even numbers without ever reaching the end.

You might think that since both sets are infinite, they must have the same number of elements. But Cantor's Paradox proves that they don't.

To show this, you can try to match up the numbers in each set like this:

1 to 2
2 to 4
3 to 6
4 to 8
5 to 10
and so on...

By doing this, you are pairing each number in the first set with a number in the second set. But you will quickly run into a problem. You will reach a point where you can't make any more pairs, because there are infinite numbers in the first set that don't have a corresponding number in the second set.

This means that the set of whole numbers is actually bigger than the set of even numbers, even though they are both infinite. And this is the weird and unexpected result of Cantor's Paradox.

So, in summary, Cantor's Paradox is a math concept that shows how trying to count infinite sets can lead to strange and unexpected results, such as one set being bigger than another even though they are both infinite.