Is Infinity a Concept or a Number?

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Discussion Overview

The discussion centers around the nature of infinity, questioning whether it is a concept or an actual number. Participants explore this topic through various lenses, including set theory, mathematical definitions, and philosophical implications.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants argue that infinity is a concept, particularly in the context of traditional number systems where no element can be reasonably called "infinite."
  • Others propose that infinity can be treated as a number within certain constructed number systems, such as surreal and hyperreal numbers.
  • One participant highlights the complexity of infinity, noting that it can behave both as a number and as a concept, depending on the context.
  • Different forms of infinity are mentioned, including cardinality, limits, and various mathematical structures like one-point compactification and ordinals.
  • There is a suggestion that the original question may be misleading, as there are multiple interpretations and forms of infinity rather than a singular definition.

Areas of Agreement / Disagreement

Participants express differing views on the nature of infinity, with no consensus reached. The discussion reflects a range of interpretations and applications of infinity, indicating that multiple competing views remain.

Contextual Notes

The discussion reveals limitations in understanding infinity, particularly regarding the definitions and operations associated with different number systems. The complexity of infinity's behavior in various mathematical contexts is acknowledged but not resolved.

romsofia
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Hey, is infinity a concept or an actual number?

This is a discussion with someone, I say it's a concept but then he brought up set theory, and I have no set theory knowledge whatsoever.
 
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Infinity does not behave according to ur laws of arithmetic(usual number)...

1/0 = inf
1= inf * 0
1= inf*(0+0)
1=2 (contradiction)
 
What is a number?
Answer:
An element of a particular number system.

A number system is a set, where you have defined some operations, i.e, "stuff" you can "do" with your elements. For example, you might pick any two elements, and according to some specified procedure associate a third element to your picked pair of elements.
Typical examples of such operations are "addition" and "multiplication" (Pick two numbers, add them, and gain a third number).

Now, in our "ordinary" number systems, there is no element that reasonably could be called "infinite". Thus, within these number systems, infinity is not a number.

However, it is perfectly possible to construct number systems in which infinity is a number as well.
 
Well, the most disturbing thing about infinity is that there are many different forms of it. Sometimes it behaves as a number, sometimes as a concept...

Infinity as a number:
- Surreal numbers
- Hyperreal numbers
(in the real numbers, infinity is certainly not a number!)

Infinity as concept:
- cardinality
- limits

Infinity as "points in the space":
- one-point compactification
- ordinals and cardinals
- projective space

So there are many different flavours of infinity. So the original question is actually not correct, since there is no one thing called infinity. There are many different object which are all called infinity...
 
micromass said:
Well, the most disturbing thing about infinity is that there are many different forms of it. Sometimes it behaves as a number, sometimes as a concept...

Infinity as a number:
- Surreal numbers
- Hyperreal numbers
(in the real numbers, infinity is certainly not a number!)

Infinity as concept:
- cardinality
- limits

Infinity as "points in the space":
- one-point compactification
- ordinals and cardinals
- projective space

So there are many different flavours of infinity. So the original question is actually not correct, since there is no one thing called infinity. There are many different object which are all called infinity...

Wow I have been trying to explain what you just said!
 

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