Does infinity exist?

It's interesting to think about it - we talk about infinity quite a lot, especially when discussing some of the bigger scientific theories. But does it actually exist?

Note that when I talk about infinity, I'm talking about actual/physical infinities (as Aristotle would put it), and not potential/countable infinities.

Actual infinities not existing wouldn't pose much of a problem for mathematics (as mathematics is an abstraction and deals with countable infinities), but it could pose a problem for major theories in physics.

Anyways, I'll try my best to play Devil's Advocate, unless I'm overly convinced. Discuss!

 

Well, the closest thing to compare infinity with is the universe itself.

And what our telescope can see is just the observable part of the universe. There's a whole lot of unseen and unexplored regions out there and it could really be infinite.


Until we find the edge of the universe (If it even exist) then I would strongly stand and say that infinity does exist for now.

 

Simply put no. The universe, according to commonly accepted theory, cannot by definition be infinite. To be completely honest though it all depends on what you believe the universe is shaped like. A universe with curved or spherical topology then it cannot be infinite, but a universe with flat topology can be infinite. I am fairly certain, and correct me if I am wrong here but it is commonly expected that the universe is curved that was one of those things that the acceptance of relativity brought on. Then assuming to cannot contain an infinity in a finite system then it would be impossible for any kind of physical infinity to exist, assuming the universe isn't infinite then there can be no other infinite in it.

Physics generally stay away from infinite number sets when working with theories, but they have found that some are impossible to avoid.

 

potentially the length of a coastline is infinite.
http://en.wikipedia.org/wiki/Coastline_paradox
Using smaller and smaller 'rulers' gives you are larger and larger result. There is no limit to how small you can go, even at the atomic level there could be things smaller than strings.

 

Technically infinity is not a quantifiable number but if the universe expands forever then yes, infinity would exist.

 

Pretty sure that's what OP meant by "counting" infinity. Such as the limit of a function as it approaches zero.

 

It's just a very difficult concept to wrap your mind around. It is literally impossible to comprehend the true meaning of infinite.

 

Okay, so for now it's infinity just because we haven't found otherwise? Just because we don't know what's out there?

Yes, that is correct - if actual infinities exists, the universe must be infinite.

Yes, exactly - in some cases, physicists refer to infinity, such as the universe having infinite mass/energy at the point of the Big Bang.

Yes, someone has already addressed this - this is simply a countable infinity.

Ok.

True, yet I do believe we talk about it comfortably, especially in regards to many scientific theories, such as the multiverse theory.

 

I like to view infinity as limited infinity and whole infinity. To me limited infinity is the space between an dimension, for example theres infinite fractions between 1 and 2. 1.111111..... and goes on. An apple you can go all the way to quarks and still do 1/4 of a quark.... and goes on.

To me whole infinity includes everything, all of the dimension numbers and goes on. I am pretty certain that the universe is not infinite due to a example I have of time, lets say there is a whole infinite string(at some shape that we cannot interpret), if you mark 2 points on the string, there would be technically be a infinite space between the 2 points. If there is a infinite past of time, then time would never reach the point we are in right now.

 

Theoretical physicist's Are working on this now actually, As for the question. I would have to believe yes for the time being, as stated above for the sole fact that there is no real determination at this time.

 

Wrong infinity, sorry!

 

And the reason for this is because it is generally accepted that we cannot fully understand or comprehend it.

 

If you think space and time is linear.

 

No, the distance between the two points has nothing to do with how far the string extends beyond those two points. You've simply marked off a measurable section of something that goes on forever.

 

It is impossible for infinity to exist in the sense that infinity divided results in infinity
If the universe is infinite no finite section of it would also be finite. That directly contradicts the existence of finite objects such as planets, stars or people.
However I will say the universe is a finite set of the infinitely random, so that a good portion of random phenomena such as life should occur

 

Okay, interesting way to put it. But don't forget - numbers are an abstraction of reality. They cannot be an 'actual' infinity, only a countable one.

The definition of infinity is to be boundless. If you were to mark two points on said string, you are going against the definition of infinity. It's like me taking the set of integers (an infinite number), and selecting the range of integers from 50-100. It no longer becomes infinite, but it doesn't mean that if the sample I took is finite, then the entire set (the integers) are finite as well. Kill dank has replied to this:

Don't worry about it

I'm not understanding - you're saying that in an infinite universe, no finite objects can exist?

 

infinity is time.

 

But time began at the Big Bang at t = 0, therefore it isn't infinite.

 

Correct me if I'm wrong, but I don't think it matters. It's like saying the set of positive integers isn't infinite because it has a starting point (when in reality, it is infinite). The set of positive integers has a starting point in its range (one) and is boundless on the other side (positive infinity). Of course, this is a countable infinity, but you get the point.

 

In our eyes, yes - In reality, probably not.