How can the universe be infinite in size?

[Airbrush]

If the entire universe really was smaller than a proton when it started expanding, and it has been expending at a finite rate. Even if explansion during inflation was a number of times faster than light speed, the expansion rate was a finite number. Then how can it reach an infinite size in a finite period of time?

 

Therefore, it appear that the size of the universe is finite.

Edited December 17, 2012 by Airbrush

[Delta1212]

That would be correct.

[timo]

My guess would be that the source you got the size of a proton from actually said "size of the visible universe" (which actually is considered finite). Otherwise, the source would make quite an extraordinary claim (or be a confused newspaper editor).

[JohnStu]

Yeah whether it's infinite or finite is up to debate still

[EWyatt]

If the entire universe really was smaller than a proton when it started expanding, and it has been expending at a finite rate. Even if explansion during inflation was a number of times faster than light speed, the expansion rate was a finite number. Then how can it reach an infinite size in a finite period of time?

 

Therefore, it appear that the size of the universe is finite.

Be wary of any "expert" that uses the word "infinite" when dealing with anything material. It is so pathetic to hear from these "experts" on how the core of any black hole is an "infinitesimal" small singularity. Or that the Big Bang began from an infinitesimal point, etc. Bottom line: when you deal with matter, nothing is infinite!

[Airbrush]

The key word here is "observable universe" which is huge but finite. Maybe the "experts" that I hear on popular science programs, when they say "universe" they really mean "observable universe"?

[Arjun Artro]

Infinity is just a word to cover up or hide all the loopholes these "experts " make when making theories. The Big Bang is an assumption. As no one is able to "prove " it wrong, it has taken its place in science to a very big extent. Nothing observable by our senses can be finite. In other words, we make these scales and we measure it. What if we're wrong somewhere? We humans never admit it. .

[PeterJ]

I would not expect physics to answer the question about the size of the universe. It is a question for metaphysics, as are all questions that ask about fundamentals.and absolutes. When we examine this question we find it gives rise to a paradox. It makes no sense to our intellect that the universe is finite or infinite. Physics is helpless in this situation and must resort to logical analysis. Or this is my view at present.

 

. .

[ZVBXRPL]

If the entire universe really was smaller than a proton when it started expanding, and it has been expending at a finite rate. Even if explansion during inflation was a number of times faster than light speed, the expansion rate was a finite number. Then how can it reach an infinite size in a finite period of time?

 

Therefore, it appear that the size of the universe is finite.

How can the Universe be Infinite?

 

It was never smaller than a proton. It never expanded. It is not expanding.

 

Suppose for a moment those 3 statements are actually correct.

 

Now it is easier to imagine an infinite universe

 

Surely in the world of Science, the first thing any SCIENTIST should do is accept the possibility that some theories maybe proven incorrect at a future date

 

This happens throughout history of science correct?

 

Do not all the great scientists themselves say that there is the possibility of even their own theories being incorrect?

 

Theory is not Law.

[swansont]

Surely in the world of Science, the first thing any SCIENTIST should do is accept the possibility that some theories maybe proven incorrect at a future date

 

This happens throughout history of science correct?

 

Do not all the great scientists themselves say that there is the possibility of even their own theories being incorrect?

 

Theory is not Law.

 

!

Moderator Note

Regardless, that's not the topic of this thread. Please don't hijack the discussion. This can be brought up in a new thread, if you wish.

[Arch2008]

When we observe something, the laws of physics explain how what we observe happens. We cannot observe the whole universe. The observable universe is finite. However, when it is taken as an example of the whole universe, what we can see almost acts as if the whole universe were also finite, but not completely. So the possibility that the whole universe may have been infinite right from the beginning cannot yet be ruled out.

[Airbrush]

When we observe something, the laws of physics explain how what we observe happens. We cannot observe the whole universe. The observable universe is finite. However, when it is taken as an example of the whole universe, what we can see almost acts as if the whole universe were also finite, but not completely. So the possibility that the whole universe may have been infinite right from the beginning cannot yet be ruled out.

So do you believe that the observable universe began smaller than a proton?

 

[michel123456]

My guess would be that the source you got the size of a proton from actually said "size of the visible universe" (which actually is considered finite). Otherwise, the source would make quite an extraordinary claim (or be a confused newspaper editor).

The OP syllogism looks correct to me.

The premise "size of a proton" does not produce an infinite universe in finite time. Only an infinite size at the beginning can produce an infinite universe in finite time .

 

As Arch2008 wrote: "the possibility that the whole universe may have been infinite right from the beginning cannot yet be ruled out." although "infinite right from the beginning" is a very hard concept to grasp.

That is not what i call simply a beginning, it is an apparition.

 

[Arch2008]

Today, as posted, the observable universe is expanding at 70km per megaparsec, which causes distant parts of the whole universe to recede faster than the speed of light. At a fraction of a second after the Big Bang, inflation caused the observable universe to expand faster than the speed of light. So more distant parts may have expanded much faster, perhaps infinitely faster.

 

The evidence indicates that the universe started out smaller than a proton as a singularity that present physics cannot describe.

[alpha2cen]

The evidence indicates that the universe started out smaller than a proton as a singularity that present physics cannot describe.

From the calculated reslts the expansion rate is very high near the beginning.

The shape of the expansion curve is very steep.

This result is calculted from the space expansion model.

Data --> simple model --> result

Other factors are eliminated.

http://blogs.scienceforums.net/alpha2cen/2012/12/24/space-expansion-model-universe-expansion-graph/

[moth]

I wonder if the concept of area-filling curves could be relevant?

In the same way an infinitely long line can be folded into a finite area, maybe an infinite volume can fit in a finite 4-d hyper-volume.

[Airbrush]

"As Arch2008 wrote: "the possibility that the whole universe may have been infinite right from the beginning cannot yet be ruled out." although "infinite right from the beginning" is a very hard concept to grasp.

That is not what i call simply a beginning, it is an apparition."

What makes scientists so sure that the observable universe had to originate from a region with a size smaller than a proton? Why not suppose the universe originated from a region of indeterminable size? If 2 branes collide, in string theory, the branes would make contact over a substantial area, maybe Billions of light years across, maybe infinite.

[proximity1]

For reasons which stem from a strict application of logic, I agree with Michael123456 @ post N° 13 and with Delta1212 @ post N° 2. No one has been able to explain how the problem as stated here:

 

"Even if explansion during inflation was a number of times faster than light speed, the expansion rate was a finite number. Then how can it reach an infinite size in a finite period of time?"

 

is escaped by word-play in which, at one point, it's objected that "universe" must (for reasons that remain mysterious to me) refer necessarily to "observable universe".

 

It isn't difficult to re-state the OP and specify that by "universe" what is meant is not "merely" the "observable universe" but anything and everything else included, "observable" or not.

 

Put that way, how is it possible to dispense with the logical problem of an "infinite space" having somehow "occurred" within what seems to me must be veiwed as a finite time-span? Unless we are now going to (again?) rework the meaning of time and its relation to space, we have a problem reconciling infinitely-expanded space within finite expansion-time, don't we?

 

As for "distant parts" of the universe (visible or not) having somehow expanded (for a 'while'?) infinitely quickly--vis: Arch2008 @ post N° 14 : ..." So more distant parts may have expanded much faster, perhaps infinitely faster." ...

 

I think the conceptual difficulty should be obvious there. Between "expanded much faster" and "perhaps infinitely faster" is a chasm that I defy any human consciousness to bridge. As applied here, "expansion" is necessarily a time-and-space relationship. That is, to "expand" we mean, inescapably, it seems to me, that in some physically real sense an area (that in which the expansion is taking place) is involved, or concerned, directly with a duration --in post N° 14 we are invited to imagine this duration as "infinitely faster"--(which, I add, happens already to imply a comparison somewhere: "faster" than what, exactly?) ---
but, again, in the OP, we are before a logical problem, just as it's expressed in the OP: an "infinitely fast" duration over a finitely limited area?

 

The implication of "infinitely faster" would seem to me to be that this speed "never ceased in its increased acceleration"--that is, its acceleration was infinite. So, in what sense does the term "was" apply there? An infinitely fast acceleration "ceased" at some point? When? When it "ran out time"? Or when it became "fast enough"?

 

I think the problem as stated is still right where the OP left it.

 

_________

 

appended: in fact, come to think of it, isn't "infinitely faster" simply a logical contradiction in terms--i.e. self-contradictory?

 

"Speed" implies a rate, and a rate would necessarily imply something finite, wouldn't it? So, infinite speed is an apparent logical contradiction. That which is infinite cannot be "rated", clocked, timed, or, indeed, subjected to any sort of humanely-conceived measurement, can it?

Edited January 3, 2013 by proximity1

[Arch2008]

http://map.gsfc.nasa.gov/universe/uni_shape.html

 

Apparently the humans at NASA have a pretty good consciousness.

 

"We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe." (my italics)

 

As I posted, the physics of the finite observable universe does not leave out the possibility that the whole universe is infinite. If this is the case, then an infinite universe with a finite age must have inflated at an infinite rate. That seems like a pretty short bridge to me.

[proximity1]

http://map.gsfc.nasa.gov/universe/uni_shape.html

 

Apparently the humans at NASA have a pretty good consciousness.

 

"We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe." (my italics)

 

As I posted, the physics of the finite observable universe does not leave out the possibility that the whole universe is infinite. If this is the case, then an infinite universe with a finite age must have inflated at an infinite rate. That seems like a pretty short bridge to me.

 

I'll offer as a logical exercise this variation on your assertions:

 

If I take your reasoning chain as is, we have, first, a premise, namely "the physics of the finite observable universe does not leave out the possibility that the whole universe is infinite."

 

that is the premise, which, in abstract form can be stated as "A does not preclude the possibility of B."

 

Next, we have the following "conclusion," drawn, apparently, from the preceeding premise: " If this is the case, then an infinite universe with a finite age must have inflated at an infinite rate."

 

Using the very same syllogisms, we may state, by the same logic, the following:

 

 

Exp. " The physics of the finite observable universe does not leave out the possibility that the whole universe is made of expanding-Pink-Elephants (revised). If this is the case, then an expanding universe of Pink Elephants with a finite age must have inflated at an infinite rate."

 

But, reading the conclusion, the reader is left to interpret the referent of "this" in ..."if this is the case, then"... (my emphasis added).

 

But to what exactly does 'this' refer?

 

Is it: "If this (i.e. "the possibility that the whole universe is infinite) is the case..(i.e. "the possibility that the whole universe is infinite)..then, an infinite universe with a finite age must have inflated at an infinite rate."

 

or, is it, rather, "If this (i.e. "the whole universe is infinite ) then, an infinite universe with a finite age must have inflated at an infinite rate."..

 

As at least some should notice, the one (assumed as true), does not logically imply the other--the other being: "an infinite universe with a finite age must have inflated at an infinite rate."

 

No one has yet explained how the logic of the OP is faulty. Instead, that logic has been persistently ignored by those who are disputing it here.

 

First, the expansion theory itself is not yet a given. So, it could well be posited--as indeed, prior to the first hypothesis of an expansionary universe (whether that is interpreted as only "visible universe" or not,) it surely was posited--that there was no expansion process. The universe formed in certain unknown dimensions and since is (or is not) expanding at the present (or at any time past).

 

Second, nowhere does any of Arch2008 post demonstrate how we may simply conclude that the universe is infinite. We're simply offered that it must be, because, apparently, since it may not be excluded "that the whole universe is infinite" then, an infinite universe with a finite age must have inflated at an infinite rate."

 

This is at once circular reasoning and, as such, a form of petitio principii.

 

That doesn't follow. And, logically, is false--no matter what the very smart people at NASA may actually believe or contend about the subject. Here, in this thread, the argument, its logic, is false and falls flat.

 

The question posed in the OP is still unanswered (and still ignored) here.

Edited January 3, 2013 by proximity1

[Arch2008]

You mean the assertions of the crew at NASA?

If a universe with finite age is infinite as indicated by the WMAP results, then it must have inflated at an infinite rate.

Pink elephants aside, what part of that doesn't answer the OP?

[alpha2cen]

For reasons which stem from a strict application of logic, I agree with Michael123456 @ post N° 13 and with Delta1212 @ post N° 2. No one has been able to explain how the problem as stated here:

 

"Even if explansion during inflation was a number of times faster than light speed, the expansion rate was a finite number. Then how can it reach an infinite size in a finite period of time?"

At the viewpoint of relativity theory we explain why it spent very small time during the Inflation.

How about this Figure?

[michel123456]

You mean the assertions of the crew at NASA?

If a universe with finite age is infinite as indicated by the WMAP results, then it must have inflated at an infinite rate.

Pink elephants aside, what part of that doesn't answer the OP?

 

(bolded mine)

 

"inflated at an infinite rate" is the modern wording for "apparition".

 

All this conversation reminds me the middle ages.

 

----------------

(edit)

 

To me the only healthy way to reach the question is the following: take as granted ONLY what we evidence shows and build a theory afterwards. Not cherry picking in order to match evidence with existing theory.

 

What we (think we) know is:

1. The Observable Universe is finite in space & in time.

2. The O. U. is flat.

3. The O.U. is expanding.

4. We can assume that the O.U. is NOT the Whole Universe but is a good sample of the W.U.

 

Point 2 combined with point 4 suggests that the W.U. is infinite.

 

IOW we are supposed to be actually observing from the inside a finite "bubble" part of an infinite W.U.

 

SO IMHO it is wiser to first understand roughly but correctly the bubble we are living in before jumping into wild speculations on how an infinite W.U. could have been "created", if that is even imaginable.

[timo]

Despite proximity1's repeated claims that the OP had been ignored, I disagree. As I said in post #3, Airbrush's conceptual problem is due to incorrect premises - owing to leaving out or over-reading the important word "visible" (which may not the fault of Airbrush but possibly of his source). Hinting to this important point completely answers the original question.

 

For the related question how a finite expansion rate can lead to something infinite arising from something of size zero, see this thread: http://www.scienceforums.net/topic/69359-infinity/

 

However, while this may seem a similar question, it is in fact something completely different: No one would claims that a finite expansion rate can result into an object the size of a proton expanding to infinite size in finite time.

 

For the record: Even though good manners would dictate it, I did not read all of the posts here (in fact I ignored most). I did not feel they really added to this rather simple issue. So sorry if I missed the point (but I did read the OP, at least )

Edited January 4, 2013 by timo

[proximity1]

I contend that as terms, and as concepts, by any reasonable notion of "infinite" (i.e. "limitless" "unbounded", ) and any reasonable notion of "rate" and "speed" (speed is implied in "expansion" over any given area, defined or undefined but existing in our accepted ideas of the physical cosmos (Yes, that includes NASA's views of that), these cannot logically combine in a sentence as asserted above,

 

"inflated at an infinite rate"

 

Infinite, as it is unbounded, without limit, cannot logically modify the term "rate," which necessarily implies a limit; whether known or unknown, that limit is, by necessity less than infinite since infinity is falsified by limits per se.

 

But, there is another so far unmentioned logical error in the assertions of "inflated at an infinite rate" when this is intended to explain and justify a theory of an infinite universe ( stipulated as including both observable and beyond what we are able to observe ):

 

again, as a logical necessity, an "infinite" universe cannot expand--ever. Neither "once upon a time," nor "in the present" nor in any finite period, continuous or discontinuous, in the past. This is apparently not immediately obvious but, upon reflection, we should be able to reason that, if universal space (including space-time as an inseparably unified conception) is infinite, it can not be "partial", now, or at any previous time. Infinite space necessarily precludes any expansion to that state of being for a simple reason that logic requires: infinity is not susceptible to "development" as it cannot be severable, partial, reducible. It is at once "limitless" in scope. Indeed, "scope" is itself inapt as a modifier of the term "infinite". Basically, our language, trapped in limits which are an inherent feature of our own physical size and mental constructions, is inadequate to properly comprehend what is infinite.

 

An infinite space cannot have ever experienced "enlargement"--- "expansion".

 

Further, the tone of some participants here, in repeating their erroneous reasoning as if they were defending what they are apparently so far unable to grasp about their own reasoning errors--the tone is very close to insulting. As Michael123456 writes in post N° 23, the discussion resembles something from the Middle Ages, where church authority brooked no dissenting views even as it imposed and enforced a world of conceptions which were patent nonsense.

 

 

You mean the assertions of the crew at NASA?

If a universe with finite age is infinite as indicated by the WMAP results, then it must have inflated at an infinite rate.

Pink elephants aside, what part of that doesn't answer the OP?

 

 

 

And, by the same token,

 

If a universe with finite age is not infinite as indicated by the WMAP results, then it need not have inflated at an infinite rate.

 

You are insistently begging the question. And so I have to wonder if you even understand what that means.

Edited January 4, 2013 by proximity1