Our Finite or Infinite Universe?

[garyegray]

I believe energy permeates throughout infinitely. The observable Universe from our vantage point, I believe, is a subset on an infinitely larger set. Also, you can find infinity within the finite, for example, you can divide any number in half, an infinite number of times - it never reaches zero and it never produces an error, you can literally keep dividing in half the result of the previous division, forever. Is the same true for energy? I tend to think it is as I do not see how you could have the smallest possible anything. We know atoms are made up of smaller forms of energy, and these smaller forms of energy are made up of even smaller forms, and so on.

Matter is made from energy and energy is composed of what Einstein called "Space/Time". We are all therefore walking and breathing "space-time".

There is no end to the Universe, only a continuation of energy in some form. Do we understand what forms this energy takes or can take? No, we do not. Some of this may be the dark energy physicists talk about, and there are probably even more exotic forms of energy that we have not begun to imagine yet.

 

[Amegioa71]

There is no such thing as "infinite". There is a set, quantifiable amount of mass/energy in the universe that was created in the Big Bang. And since neither mass nor energy can be destroyed, only transformed, then the same amount of mass/energy that existed then, exists now. Is there a boundary at the 'edge' of the universe? Unlikely. Two objects, say galaxies, are moving apart because the universe is expanding. They're not shooting outward like debris from an explosion. The space between the two objects is expanding, it is the space moving, not the objects (though all things in the universe are in motion, but I speak of the general expansion of the universe).

If there was a 'boundary'. It could never be verified. The space expanding between us and it would never allow us to get there. It'd be like walking the wrong way on one of those escalator walkways in the airports except that the escalator is speeding up, ever so slowly, constantly over time and the destination is billions of light years away. Eventually our ability to move forward would be overwhelmed by the speed of the escalator and even at a full run, we'd still be moving away from the destination.

 

[mjr150]

The human mind tells us that infinity can't exist. Probably because we can't comprehend it. When you look at a black hole for example, to my understanding, when matter falls into it, the event horizon contains all of the 3 dimensional space matter in the form of a 2 dimensional sphere. I can't comprehend that either, so maybe the universe is infinite.

When you think of a balloon, the surface is 2 dimensional but limited. We can't imagine in our minds 3 dimensional space that wraps itself into a finite bubble, but it can be expressed it mathematically. In other words, if you where to send and ant into a specific direction on a balloon, it would walk around it returning back to where it started.

Similarly if you shoot a photon into a specific direction into a bubble type 3 dimensional space, it would eventually return back to where it started. I like to believe this is the universe we live in.

 

[adharr]

Very cool discussion and I appreciate all the contributions. However dear "jeenius", I do not appreciate the "put down" and am not on this discussion board to try to make myself look smarter than everyone else. The preponderance of the discussion has been just what I was looking for as an intellegent, open discussion of alternative viewpoints with people who have similar interests.

I am familiiar with set theory and find that concept very applicable to my original points actually. The problem is that while you made fun of my ignorance of such things and claimed it was all really very "simple", you also described your sets as distinguishable by "all that is not forbidden" and "everything that is possible" in the universe. So, my friend, you have gotten back to my original question as to how we can apply "finite" terms of measurement to what appears to be an "infinite" universe? What I'm asking is for you to give me a scientifically discernable definition of what you in your infinite wisdom are "forbidding" and what you are "including" in your set. If we are able to do that it would seem to me, then and only then, would we have any hope of applying "finite" terms and measurements to something that we otherwise seem to label as "infinite".

Additionally, I am not trying to "prove" anything. I am just throwing-out a proposal for one alternative way that to me provides some scientifically based attempt at giving some kind of tangible meaning to what now seems to be a totally undefined term. While I'm not trying to change the world and no matter what any of us might propose in this forum, the real purpose of this string is mostly just a little enjoyable intellectual exercise.

 

[ZenDraken]

Infinite, duh....
A finite universe is literally impossible.

You can have a "bounded" infinite universe.

Think of the video game "Asteroids". (For those of you not born in the Jurassic-era: In Asteroids, you flew a little spaceship around the screen, blowing up asteroids.)

In Asteroids, if you flew past the edge of the screen, you'd reappear at the opposite edge. So while the Asteroids "universe" was completely shown by a finite screen, it was also infinite in the sense that you could travel in one direction forever. Of course, you would eventually return to your starting point, but the effect was that you were flying in an infinite universe.

There are some theories that say our universe is like this, that if you flew in one direction long enough, you'd end up back at your starting point. So the universe would have a finite volume, but be infinite in extent. There would be only so much universe out there, but it would not have any real "edge".

The surface of the Earth is similar: It has a finite surface area, but you can walk in one direction forever.

Hope that's some food for thought...

 

[Couerl]

The surface of the Earth is similar: It has a finite surface area, but you can walk in one direction forever.

Hope that's some food for thought...

Well I was thinking something analogous to that. Since space itself is expanding it's almost like a mid-oceanic ridge where new crust is churned up and the sea floor literally expands and yet the islands and continents remain virtually unaffected and float merrily along right on top of it.

 

[Paul_L_Smith]

Is the universe finite or infinite?

Will it expand forever or collapse into the "big crunch" ?

Latest observations point to the fact that the universe is not just expanding but the expansion is accelerating. If there was enough mass, then the expansion would be slowing down and the universe would eventually collapse into another singularity.

Another way to phrase it, is the universe "open" (expand forever) or "closed" (will collapse eventually).

In a closed universe, a "geodesic" or straight line is actually a "great circle" (non-euclidean elliptical geometry). Light bends because of the curvature of space time and if there is enough mass in the universe to prevent light from escaping then the universe is closed and we are all by definition living inside the event horizon of a universe sized black hole. Therefore, a finite universe.

In an open universe, a "geodesic" is an infinite line but it bends with the curvature of space-time. (think of a saddle shape) This is the other branch of non-euclidean geometry, hyperbolic geometry. IN this case, there is not enough mass to prevent light from escaping or being bent back on itself, so it would go on forever. An infinite universe.

Current observations point to the open/infinite universe due to the acceleration of the expansion and the fact that we can find enough matter (light or dark) to hold it together.

 

[gborchardt]

As many responders indicate, the current assumption is that the universe is finite. But what if we assume just the opposite? The result is Infinite Universe Theory, which solves many of the paradoxes of the Big Bang Theory. See:
http://scientificphilosophy.com/Downloads/IUT.pdf

Glenn Borchardt

 

[Jerromy]

My two cents... that's all need to be concerned about for this line of logic. The entire universe is simply two cents, and whether they can move away from each other and continue to seperate or at some point they would reach any type of boundary where they would be considered approaching is irrelevant... they could continue their relative motions through an infinite amount of the concept we label as time. If everything in the universe (there can be nothing more than everything) were to cease to exist and never again would exist, then the only real proof of a finite universe would be the lack of anything everywhere.

I can easily conceptualize an area of space being completely devoid of energy and matter and with nothing in any given boundary to vibrate the temperature as we define it would be absolute zero. With new concepts emerging in quantum physics there could theoretically be a negative kelvin temperature where matter or energy could be "sucked" out of existence and "pop" into existence somewhere else through "quantum foam". It could explain how my things disappear and reappear when my budding scientists claim they don't know how it happened... :lol:

Final note: the proposed "big bang" assumes everything that exists now also existed then as "space itself" began to expand... was it done contracting at that point? ... was this the first and only time space "started" expanding? This theory states nothing more than "This is the beginning of what we observe and understand in our narrow little view of infinity!"

 

[SpeedFreek]

SpeedFreek yes, of course I was referring to the observable universe, as I have responded in my previous post. Hopefully you have understood that if you read it in its entirety

Which previous post? The post I quoted from, which was your first in this thread, talks of the observable universe being absorbed into other surrounding universes (a very strange notion!), rather than the whole universe expanding and us only being able to see a small part of the whole universe.

 

[adharr]

The difficulty I have is how virtually all of us seem to accept the scientific assertion that the universe is 14.3 billion years old or whatever number you want to identify when by accepting that statement, it seems to inherently imply some understood "boundaries" to the "set" we are calling the universe. All I want to know is exactly WHAT is 14.3 billion years old? What is meant by that statement? It obviously implies that "something" is 14.3 billion years old and that it cannot be boundless. For if it was boundless and therefore infinite, how can we attach an age to it?

 

[MeteorWayne]

Aha, you have by your own standard proved the Universe is finite, since the evidence it is 13.7 billion years old is overwhelming.

But of course, it's infinite as well

 

[SpeedFreek]

The difficulty I have is how virtually all of us seem to accept the scientific assertion that the universe is 14.3 billion years old or whatever number you want to identify when by accepting that statement, it seems to inherently imply some understood "boundaries" to the "set" we are calling the universe.

The figure our current "best model" provides is around 13.7 billion years, and it is a boundary in time and space that marks the time, relative to today, when all the space in the observable universe, and everything within that space, was contained within such a small volume that our current laws of physics break down, so our notions of time and space can reach back no further. It is where time and space disappear, to our current laws of physics, 13.7 billion years ago.

All I want to know is exactly WHAT is 14.3 billion years old? What is meant by that statement? It obviously implies that "something" is 14.3 billion years old and that it cannot be boundless. For if it was boundless and therefore infinite, how can we attach an age to it?

The universe, which seems to have a finite age, might be infinite in distance.

There might today be galaxies in space from here all the way towards infinity, that are all part of a universe that is only 13.7 billion years old. We can only see a certain distance, because light has only had 13.7 billion years to travel.

When we use the currently understood laws of physics to make predictions about the universe in the past, the universe is found to get more and more dense, as everything was closer together. It gets hotter, and at a certain point we reach the stage when atoms cannot form anymore. So we predict that, during the early stages of the universe, it was so hot and dense and energetic that there were no atoms yet, and as the universe expanded and cooled, atoms formed. (This is a highly simplified explanation, don't take it word for word!)

At that time, the universe was full of light, able to move freely for the first time since the universe began. When the conditions were right, light could move freely without continually banging into things as the universe was so hot, dense and energetic! :lol:

The laws of physics predict that we should still be able to detect that light today, coming in from all directions, but that light has been stretched into microwaves due to the expansion of the universe for the last 13.7 billion years. We detect that cosmic microwave background radiation, coming in from all directions, which is thought to have been emitted 13.66 billion years ago, only 400,000 years after the universe "began".

 

[SAntczak]

The idea of a cosmological horizon is an interesting one and fits into the multiverse concept pretty neatly. It's also fun to imagine what the existence between the universes that make up a multiverse might be like.

Perhaps that existence, which is in effect what I like to call potential universe, since that's what our universe may be expanding into, maintains quantum mechanical zero-point energy: "Because of the uncertainty principle all physical systems, even at absolute zero temperature, have a zero-point energy that is greater than zero."

That could totally mean that whatever exists between the various universes that make up the multiverse does indeed have a temperature of absolute zero, and in fact could be the ONLY place that the temperature of absolute zero exists.

Also, this still makes our universe effectively infinite, since you could never actually observe, or travel, beyond the edge of our universe

I think it's a cool idea.

Of course, I could be wrong. I'm no scientist, nor do I even play one on TV.

 

[a_lost_packet_]

I am familiiar with set theory and find that concept very applicable to my original points actually.

That's why I mentioned it. It simply seemed to be a rehash of something that is already understood.

The problem is that while you made fun of my ignorance of such things and claimed it was all really very "simple", you also described your sets as distinguishable by "all that is not forbidden" and "everything that is possible" in the universe.

So, my friend, you have gotten back to my original question as to how we can apply "finite" terms of measurement to what appears to be an "infinite" universe? What I'm asking is for you to give me a scientifically discernable definition of what you in your infinite wisdom are "forbidding" and what you are "including" in your set. If we are able to do that it would seem to me, then and only then, would we have any hope of applying "finite" terms and measurements to something that we otherwise seem to label as "infinite".

"All that is not forbidden" refers to the Totalitarian Principle. In a nutshell, that which is not forbidden is compulsory. Given your background in nuclear physics, I thought the statement would have been crystal clear with that reference, especially in a discussion about cosmology and an infinite Universe.

A very surprised cat wearing a pinstripe suit could suddenly appear floating in space, in complete vacuum, somewhere in our, possibly, infinite Universe. There is nothing that expressly forbids that. It may be highly unlikely at any given time, but it is not forbidden. However, because of the way our Universe appears to work, he could not travel at the speed of light through normal space. That is forbidden.

Outside of the set of compulsory possibilities resides the area in which your platonic "zero K" measurement takes place.

In any complete set of "everything" there must exist a set of that which is possible and a set of that which is not. A is possible. A' is not.

Simply because you have listed something as "impossible" does not mean it has any special relevance as the set A' includes all the other impossible things as well. If you offer it as evidence for what is "outside" of our Universe (A), than anything which is impossible can also be included. Granted, giant pace hamsters and unicorns are possible within our Universe, so they really wouldn't be included in that set. I took a bit of literary license there.

Additionally, I am not trying to "prove" anything. I am just throwing-out a proposal for one alternative way that to me provides some scientifically based attempt at giving some kind of tangible meaning to what now seems to be a totally undefined term. While I'm not trying to change the world and no matter what any of us might propose in this forum, the real purpose of this string is mostly just a little enjoyable intellectual exercise.

I understand. I agree such topics can be interesting to discuss. But, when you make a claim of a very strong nuclear physics background, I have to wonder what the level of discussion is. The evidence offered thus far doesn't seem to support that claim. I don't make such a claim and even I, neophyte to nuclear physics that I am, see what should be obviously identifiable errors for someone with such knowledge. Maybe you had a rough night, I don't know. If so, my apologies for reacting a bit strongly to such a claim. I've had my fair share of foot-in-mouth posts as well. If that is the case, please elucidate further on the significance of Absolute Zero being the condition of "outside" of the Universe due to its impossibility within it and I will be happy to discuss it meaningfully if I am able.

But, simply offering "nothing" as proof, when any bit of nothing will do, isn't really evidence of anything, is it? I don't know what to do with "nothing." But, "something" - That I know what to do with.

 

[a_lost_packet_]

..Think of the video game "Asteroids". (For those of you not born in the Jurassic-era: In Asteroids, you flew a little spaceship around the screen, blowing up asteroids.)

In Asteroids, if you flew past the edge of the screen, you'd reappear at the opposite edge. So while the Asteroids "universe" was completely shown by a finite screen, it was also infinite in the sense that you could travel in one direction forever. Of course, you would eventually return to your starting point, but the effect was that you were flying in an infinite universe....

And, under certain conditions, it's also considered one possible way to travel back in time.. if you could move fast enough, that is.

 

[NotLifeAsWeKnowIt]

A very simple comment on a tiny portion of this discussion:

Absolute zero might be the same as infinitely hot, as far as reaching it is concerned. Really cold might be 10^-6 K, but there's always 10^-7 K that's even colder. Using Real numbers, 10^-(infinity) is required to get to "absolute zero". Just as reaching (infinity) degrees isn't going to happen, reaching 10^-(infinity) is hard.

I say absolute zero "might be" like infinitely hot because quantum mechanics is weird and poorly understood by me. Perhaps there is a way to get really cold then emit a quantum of heat to reach absolute zero. I'm not qualified to discuss that, but I nevertheless wanted to pretend I was contributing to the conversation.

 

[ndelange74]

Adharr, your solution is not acceptable, because it offers an answer that can only ever be theoretical.

A much better, and fully practical, solution would be to define the limits of the universe as being the age of the universe, since space and time are the same concepts. Thus, the amount of time that has passed since the birth of our universe will be identical to the distance that our universe has expanded since its birth.

As such, we can therefore state quite clearly that the universe is unquestionably finite in scope. Of course, we do not know what lies BEYOND the first moment of our universe's existence - both with regards to space (what medium, if any, existed before our universe was born, and into which it was born) and time (whether there was a time before time).

 

[postman1]

So, here is my question:
Accepted theory now says that everything is accelerating as it moves away from the big bang. If this is the case, and we run things backwards to find the beginning, we would have to move everything slower and slower, the farther back we went. How then do we ever get to a beginning? It seems that we could never quite reach that point, but what do I know. Can anyone explain this for me?

 

[terranspace]

matter is finite but energy is infinite. I guess it is how you want to look at the universe, as something tangible or something more than what meets the eye. I think that as long as our universe has matter it will be argued as having some sort of bound but with space time ever expanding into what ever lies beyond our reality and current understanding it will be argued that it is without boundaries.

 

[state_of_wa]

Maybe time can change??

So, here is my question:
Accepted theory now says that everything is accelerating as it moves away from the big bang. If this is the case, and we run things backwards to find the beginning, we would have to move everything slower and slower, the farther back we went. How then do we ever get to a beginning? It seems that we could never quite reach that point, but what do I know. Can anyone explain this for me?

I have no answer for it. Makes sense but I wonder if time itself could change to account for it? It is a constant now but in the strange conditions that some try to descibe for the first milliseconds of a big bang event could time slow down or speed up?

 

[state_of_wa]

So, if absolute zero cannot exist within our universe, I think we can say that it could theoretically only exist OUTSIDE of our universe. Therefore, that would seem to me to imply a clearly definable "theoretical" boundary for ascribing the limits of our universe. In other words, a place beyond where any matter or energy as we know it exists.

Now, if that is the case, then just as our attempts to achieve absolute zero here on earth find the goal to be infinitely far away, then that would also seem to hold true at the boundaries of the universe. In other words, there can be no finite boundary and the universe can only be said to be infinite.

A valid question to which I do not know the answer - Do electrons cease to move about the nucleus of an atom at absolute zero? Isn't temperature a means to measure energy released by moving matter? It seems to me that if electrons do move at absoute zero then it is not something that can ever be achieved. But this is not my field so I am going by gut instinct.

However, with this in mind and if I am correct, if we can assume that there is a place inside of an infinte void into which our universe has expanded then outside of this limit there is no matter. Without matter would not this be a place of absolute zero even though it could never be measured? Would our laws even apply here or do the laws only apply to that place into which our universe has occupied? I am not drawing a different conclusion than you I am just wondering if a temperature measurement is the right question to ask even though in doing so you have reached a supposition that I am not disagreeing with (although I don't know) that there is no real boundary and thus the unverse is infinite. But is is a fun exercise you've embarked on just the same.

 

[Andor]

Because we Humans cannot understand infinity! Why? because for us everything has a beginning and end.
How can we discuss this as we still don't know what Time.Gravity. Strong and weak atomic forces are?
If we were all blind, would we still measure in light years?
For me discussion ends.

 

[normalthinker]

The universe cannot be infinite in size as there was a Big Bang. The thing about an infinite number is that if you divide it by any other number, including infinity, the answer will always be infinity. During the Big Bang and the the tiniest fractions of a second after the Universe was microscopic in size (smaller than an atom and definitely not infinite), until inflation kicked in and almost instantaneously expanded it.

The universe, in my thinking is a finite (vastly enormous) but unbounded volume. Unbounded means that there is no centre and no edge. Yes this is hard to get your head around such a concept but it is easier to imagine if you consider this analogy:

Imagine you are a microbe living on a large and totally smooth planet. To you, your universe appears to be "flat" and 2 dimensional. You can move left, right, backwards, forwards or any combination of these, but up and down have no meaning. Now, imagine you set off on a long journey moving in a straight line. What will eventually happen? You will end up arriving at the location you set off, having never met an edge or a centre. This is because your 2D universe is curved in the 3rd dimension (I.e. the surface of a sphere).

Scaling this up to the real universe, we could set off, going straight up, on a hyper-long journey from the north pole of the Earth, moving in straight line, and eventually you would arrive at the South pole, having never met an edge or centre. Our 3D universe is curved in the 4th spacial dimension. (i.e. it is a hypersphere).

What is infinite is not our individual universe, but the multiverse of which universe is a member of.

 

[Space_from_Earth]

It is really depending on how you define the term "universe".

If you define it as a finite system (nomatter whatever huge it is), it is finite.
If you define it as some system covering everything, it is infinite.