The Infinities
No discussion of zero is complete without discussing its distant
cousins - infinity and infinitesimal. Infinity is the term we commonly use
for uncountable things or immeasurably large quantities. Infinitesimal is
the inverse - infinitely small but greater than zero.
There are at least three distinct types of infinities, although they
are commonly treated indiscriminately. To differentiate between these
let's call them Type 1, Type 2 and Type 3.
Our "Type 1" infinity is simply an unbounded quantity with
any value other than zero. We can define "infinitesimal" to be
as arbitrarily large or as small as required, as long as it is not equal
to zero. This is the same whether zero is viewed as { 0 } or { }.
Example:
1 / infinitesimal = infinity
Our "Type 2" infinity is generated only when zero is viewed
as { 0 }. It is generated by division by zero and only by division by
zero.
Example:
1 / 0 = infinity
The logic behind it is this: Subtract zero from one, then if the result
is not zero, repeat.
The "Type 3" infinity can be best described as "the set
of never-ending things". Never-ending distances and infinite loops
also fall into this category. This is much the same whether zero is viewed
as { 0 } or { }.
Example:
The number of odd integers = infinity
The Same but Different
The various types of infinities have many things in common and some
subtle differences. For example, here we differentiate Types 1 and 2,
which are the result of division, from Type 3 which can be described as a
simple endless loop.
Also, contrast a Type 1 infinity with a Type 2 infinity. A Type 2
infinity is infinitely larger than a Type 1 infinity, as zero is
infinitely smaller than infinitesimal.
In calculations, Type 1 and Type 3 infinities can generally be replaced
with the words "any number". Type 2 infinities do not follow
this rule - they are the results of a division by zero.
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