eli5 What does ‘Aleph Null’ mean in mathematics?

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I’m trying to get to grips with what this term means. I’m interested in mysticism, philosophy etc and it seems like a fascinating idea especially considering the symbolism of the Aleph.

I have absolutely no maths knowledge… Just a GCSE in maths and some mental arithmetic.

Edit; thanks everyone for your useful responses!!

In: Mathematics

10 Answers

Anonymous 0 Comments

It’s the smallest infinite cardinal, by definition.

Cardinal numbers measure “how many things” are in a set (broadly speaking), aleph null describes the size of any set whose elements can be assigned a positive whole number in a 1-to-1 manner. Such sets are also called “countably infinite”.

Take the set of even numbers for example

* 1 -> 2
* 2 -> 4
* 3 -> 6
* and so on and so forth.

Every even number can be assigned to exactly one positive whole number, so we say the cardinality of the set of even numbers is aleph-null.

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