I cannot understand how there are “larger infinities than others” no matter how hard I try.

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I have watched many videos on YouTube about it from people like vsauce, veratasium and others and even my math tutor a few years ago but still don’t understand.

Infinity is just infinity it doesn’t end so how can there be larger than that.

It’s like saying there are 4s greater than 4 which I don’t know what that means. If they both equal and are four how is one four larger.

In: Mathematics

34 Answers

Anonymous 0 Comments

So from your question it seems like you are conceptualising infinity as a number. In this case, we want to be thinking about infinite sets, i.e collections of numbers following a definition that contain infinite members.

When comparing the size of infinite sets, we look for a bi directional function that can take any member from one set and map it to the other set.

For example, using the sets of all positive integers, and the set of all integers, we can come up with a formula that maps all even integers to the positive integers, and all odd integers to native integers in such a way that every item in each set is mapped to a single item in the other set. This means that the set of infinity are the same size.

If we now take the two sets of “all of the fractions between 0 and 1, and all numbers between 0 and 1”. We can map every fraction to a number between 0 and 1 by just writing it out as a decimal, but there are plenty of numbers that cannot be mapped to a fraction (i.e pi/3). So because every fraction has a corresponding element in all numbers, but not all numbers have a corresponding fraction, we can say the set of all numbers is bigger than the set of fractions, even though both are infinite

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