Science a GoGo's Home Page Forums General Discussion Physics Forum Is the physical world real?

B.S. You seem to have some problem grasping the meaning of infinite. It simply means that something cannot be counted, even in principle. There is absolutely no reason you cannot count a subset of an infinite group. Infinity is a mathematical principle, but then a whole lot of other things that are mathematical principles have physical interpretations. So infinity can be used just as well for physical interpretations as 1 + 1 = 2. Maybe you should see if you can find a copy of George Gamow's book "1, 2, 3 ... Infinity". It has a fairly decent discussion of infinity in it.

In the meantime you might just accept the fact that infinity in a physical terms doesn't mean much. If the universe is infinite in time and/or space all that means is that it is uncountably large. But we don't really have to handle the full extent all at once. We just have to handle the subset that we can observe and that part is a countable subset of the whole universe.

As an example. Suppose out in my back yard I have an infinitely large pile of rocks. I decide to build a wall to hide the pile, so I go out and select 200 rocks out of the pile to use in building the wall. The pile is still infinitely large, but I can certainly work with the pile one rock at a time.

Bill Gill

Perhaps we just have to agree to differ. From my perspective it seems that you have a problem grasping the difference between mathematical and physical infinities. Of course, many mathematical truths equate to physical truths, but not necessarily all.

One trouble with just agreeing to differ is that it would leave both of us looking at the other, thinking "He doesn't get it".

Your example of the infinite pile of rocks in your back yard illustrates my point, to some extent. Although this presents a perfectly good hypothetical example, it won’t work in practice, because you cannot have an infinite pile of anything. Your pile of rocks is not an infinite pile, so, of course there is no problem dealing with individual parts.

Interesting discussion but:


...one is tempted to differ in the light of certain other threads on the forum.

Valid point there, Rede, even I will not argue with that.

I know I have asked this question before, but response tends to be sparse: does anyone believe that something finite can become infinite?

See I do believe in the science of observation, so how do we age and die :-)

Given your response above we must die based upon genetic termination or tragedy a common view even among scientists.

I have a problem with that if it was a simple effect we should have seen a truncation of it by now given our population numbers. The genetics scientists should have also seen something by now.

So you either believe aging and death is like Asimovs 3 robots law its programmed into our core and can't be truncated or there is an unseen not understood effect at play. I am actually working with a QM group on the later but its way off thread here so if you are interested Bill S lets take it to another thread under the reference of quantum biology (http://en.wikipedia.org/wiki/Quantum_biology) a reasonable layman background (http://www.anti-agingfirewalls.com/2011/05/23/quantum-biology/). Genetics goes at the problem (http://medicalxpress.com/news/2011-10-secrets-life-sought-dna-elderly.html)

My final comment is to look at the honey fungus (http://en.wikipedia.org/wiki/Armillaria)



Given enough time and food how big do you think this guy can get and yes it is one of the things the group is studying :-)

I do, so long as I can change something :-)

Anyone who buys conventional big bang theory has to believe it as well.

Rede been a while since I read Brian Greenes book, I know you have recently, but it had the calculation in it for exactly how much matter you needed to start big bang. I had not actually seen that anywhere else it was one of those weird facts only Brian Greene would know :-)

I am repeating the same question: Can we have an infinite number of finite things? Will it not be illogical to say 'YES'?. IMO, there can be limit to the number of finite things, but the limit is arbitrary. Bill S says in such cases, we can call it just unbounded or 'boundless'.

So I think it would be logical to have a 'physical infinity' termed as 'boundless' to represent a physical limit that can be arbitrary.

I am clearly missing something in english translation here

You and some seem to be getting hung up on =>
"Can we have an infinite number of finite things"

To me thats a complete consistant statement because you haven't put a context around it or as you would call it a bound, you have made an open statement.

Can we have an infinite number of finite things in a defined range or bound .... NO.

The only reason this comes up is in the context of the universe being infinite.

The universe is an enigma it is both finite and infinite depending how you look at it. You can play all the word games you like you can't get around that reality.

To put it in perspective I will ask you a much simpler interpretation is your ability to think infinite or finite.
See here is the same problem in a much more constrained and easy to understand realm.

The answer is both, you only have finite nuerons so you can only store a discretely finite maximum number but that number is huge. You can also recycle and erase or drop thoughts and that rate is alot faster than you save them so the answer is also infinite.

You need to be entirely sure of the context you are asking the question as to know which of those answers to give.

I have seen wordplays around that same thing with human memory but realize they are wordplays you need context to give the answer and that is not unusual.

Does a ball fall down if I drop it ... not if I am in a centrifuge.

Any statement or question requires context ... all the wordplay I have seen revolves around context not actuality.

To most scientists the universe is both finite and infinite we need context to decide which answer to give you and it's the not giving context that creates the ambiguity.

Regarding the difference between mathematical and physical infinities, I agree with you. Mathematics and physics are two independent domains. Mathematics is a toll that we can use in physics. We cannot replace 'physical concepts' with 'mathematical concepts'.

In my opinion (based on my theory), the quantum nature and finiteness are related. An entity that is made up of identical fundamental particles can be regarded as quantized. The fundamental particles will have finite qualities and so the entity will be finite. An entity that have no such basic units is not quantized, and so will be infinite.

Space and time are not quantized, and so are infinite. Space and time without matter represents the reality of nothingness - we can even say there is no physical world. When matter comes into into the arena, there is something that exists in the space; existence is something connected with time.

Unlike space and time, matter is a quantized entity; so any system made up of matter is finite, and we have a finite universe. Can there be an infinite number of finite universes? It is illogical to say 'Yes'. But there is no theoretical limit; you say then it can be called 'boundless'. Does 'boundless' also mean infinity? 'Boundless', I think, should be defined as a physical infinity, thus distinguishing it from the mathematical infinity.

It is an open question. It is a basic question. Before we try to answer what the universe is, I think, we have to answer this question. The question is put independent of the nature of the universe.

In a defined range, it would be finite (always?). Your statement "You can also recycle and erase or drop thoughts and that rate is alot faster than you save them so the answer is also infinite" is incorrect. The number of times you do these (erase, recycle and drop thoughts) will be very very large but will be finite.

Regarding the universe, what you have pointed out is correct. Some aspects may be finite but some other may be infinite. However, IMO, there is ambiguity in the present concepts even when the contexts are given.

In a defined range the answer is most certainly finite of anything there is a mathematical proof which for the life of me I can't think of for the moment ... arg finite memory :-)

Euclid in 300BC actually proved there infinite number of prime numbers it's remarkably simple (http://aleph0.clarku.edu/~djoyce/java/elements/bookIX/propIX20.html)



Incorrect turn it to a simple physical test.

Make a hole in a bucket allow water to flow out faster than you are filling it ergo you can never fill the bucket ... QED

Your brain memory works like that in this mode ... in the bucket you can have mini containers which remember things you choose (our permanent memory).

Thats the key point we haven't stated you have to remember permanetly said thought ... see context.




Give me context and I can give you what I would call a reasonable answer. Sure I can't be absolutely certain but I can give you an answer consistant with observations and really thats all that matters. Anything beyond that is philosophical or religious not scientific.

Enormous! but it will never be infinite. That would require infinite time. In other words; it would never get there.

Can you explain to me how, in your understanding, something finite actually becomes infinite?

No word games; just a straightforward, physical explanation that even a "hitch-hiker" can understand.

Absolutely right, but the process cannot be physically infinite, because you can never reach a point where you can say "I have done this for an infinite period of time". Boundless, yes; because there is no point at which you can say "I can go no further with this". Infinite, no; because you never reach a point at which you can say "this is infinity, I have reached it".

I don't think I will reply to any particular post. I will just put out some comments that I think are pertinent.

As far as boundless and infinite are concerned. Boundless and infinite cannot, without some context, be used interchangeably. The surface of a sphere is boundless, but certainly not infinite, since it can in principle be measured to any desired accuracy. Mathematically and physically boundless just means that you can't find a boundary. Infinite on the other hand means that in principle you can always find more of something, no matter how much of it you have already found. The normal example is of course the integers. Name any integer and I can find a bigger one.

B.S. you don't like my pile of rocks. Ok, let's assume an infinite universe. Then there are an infinite number of atoms in the universe. But I can still take out atoms individually or in clumps, such as the clumps making up the rocks in my rock pile, or in my body.

Back to the integers. They are just a way to figure out how many of something there are. If you have a pile of apples and a pile of oranges and you want to know which you have more of you can just start picking them up one at a time. One apple, one orange, one apple, one orange... and so on. Sooner or late you will run out of either apples or oranges. Then you know that you have more of which pile still has some fruit in it. And integers are just a short way of comparing 2 piles. You can count the apples, 1, 2, 3...n, then the oranges 1, 2, 3...m. Then compare the numbers, which ever number is bigger is represents the pile that has more fruit. In principle I could have an infinitely large pile of apples and/or oranges. Then I could never run out when I started either matching or counting them. But I could keep on counting forever. And at any time I could stop and I would know how many I had counted, without ever having reached infinity. So there is no reason at all not to be able to work with a countable subset of an infinite space.

As to whether something finite can become infinite. I have been avoiding that question. However, I generally feel that a finite set cannot become infinite. However, that still doesn't keep me from working with a finite subset of an infinite set.

I keep using things like set and subset to represent anything you want them to represent, because that is more general. When talking about an infinite quantity of something you can be talking about an infinite quantity of almost anything, apples, numbers, atoms, space, whatever. But the rules apply to whatever you are talking about. Using words like set and subset allow you to discuss them without specific reference to any particular set.

Bill Gill

Agree, absolutely!



Of course, but you can never show me an infinite number of integers, so the concept can never become a physical reality. It remains an idea in your mind, which probably is not infinite.

A question I must ask is: How do you know when (if) you have an infinite number of apples, or bananas?

here you go 3 lines of c code that go infinite

while {
// Do soemthing in loop
};


Take a laser point into space turn it on ... turn it off. The laser beam will go on infinitely.

There are many things that are finite but will go in infinite unless you define a condition. Infinite loops are common in programming if your dont correctly terminate the condition the same is true in nature.

But see there you go you provided a context or condition.

Okay I think I get what you are asking is there anything that can be infinite with real world conditions, so real world conditions is the context.

The answer is most definitely no.

Even the universe from big bang point of view is most definitely finite if you view it like that. Infact you cant do Big Bang calculations without making it finite :-)

It has to be because at the start there is a distinct compaction of plank distance you cant exceed.So one plank unit of time after the big bang singularity the universe size is finite and defined and therefore it is forever after when you use this context.

The problem is noone is ever going to experience space like that it's simply a thought experiment and a useful thing for doing calculations on big bang but you will never see that context it's probably impossible.

So in unconstrained context you want as given by the big bang the universe is most definitely finite.

The problem is we live in the universe and for us it is most definitely infinite. Its infinite because of context we are in it and there is no escaping that.

In the same way you may ask what is the universe expanding into. The answer is again contextual. I would say nothing because you will never see it experience it or know what but of coarse the real answer is into something which will forever remain a mystery to us call it un-space or mystic ether or whatever you like ... what does it matter you and I will never experience it. The universe space is our prison and what lies outside the walls well we leave that to religion and philosophy.