Is our universe a closed system?

[Jig]

The title of this thread is pretty much my question. I've also made this a poll to see what people in this forum think in general.

What are the proofs that our universe is a closed system?

I'd also like to hear more on the proofs that are used to show our universe had a beginning.

Thanks.

 

[h2whoa]

The universe? Possibly. I don't know much about multiverses, interesting as they are. If one universe is all there is then I would imagine, by definition, that the answer is yes.

Our planet on the other hand? Nope. Not a closed system.

 

[Dragar]

Edit: Actually, I don't think it's sensible to talk about the energy of the whole universe. The words 'closed system' aren't defined for this case.

 

[Chalnoth]

Nope, not a closed system. It's kind of hard for it to be a closed system when it is, for all intents and purposes, infinite in extent.

 

[Meiri]

Not to mention if the multiverse theory is true and it's possible to open wormholes between our universe and others...

About the universe having a beginning, the big bang isn't necessarily the beginning of the universe, we use it as a reference point because we don't know what came before it.

 

[Jig]

Nope, not a closed system. It's kind of hard for it to be a closed system when it is, for all intents and purposes, infinite in extent.

If our universe is not a closed systemin itself, then it has to be part of a closed system, no?

As for it being infinite, are you saying the our universe is eternal? Do you also think 'time' is eternal? It is my understanding that if there was an infinite amount of 'time' before today...today would have never come.

 

[Chalnoth]

If our universe is not a closed systemin itself, then it has to be part of a closed system, no?

Not in the least. Why would you think that?

As for it being infinite, are you saying the our universe is eternal?

Well, we don't really know. But it does seem that our universe as we know it will be able to support life for something like 70 billion years. Will things change before then? Well, we don't really know. But since the universe has been stable for the past 13.7 billion years, it's unlikely that we have to worry about any drastic changes, even if such changes are possible.

By infinite, I meant infinite in extent. At the very least, the universe as a whole must be vastly larger than the part of it which we can see, for the simple reason that we can see no edge: the universe appears to be uniform out as far as we can see (provided you take the consideration that looking far away is looking into the past into account). And because we won't ever be able to communicate with the universe past what we can see today, there is no reason to worry much about the extent of the universe in terms of what it means to us today.

Do you also think 'time' is eternal? It is my understanding that if there was an infinite amount of 'time' before today...today would have never come.

Well, that we also don't know. We can only see so far back into the past (13.7 billion years), so we may never have anything more than speculation as to how things truly started. Today we have a number of ideas, but don't yet have much of a way of testing them. Now, I don't want to say that we can't ever discover how existence got started, or whether it's always existed, but right now we don't know. The best we can be sure that we can find out about is the beginning of our own, visible bubble of the universe. There are a number of experiments going on now to find out about the origins of our own little bubble. Where will this lead us? Well, we don't know, and that's what makes it so exciting!

 

[Jig]

Not in the least. Why would you think that?

Since non-existence doesn't exist (obviously), there is nothing outside of existence. Therefore, existence itself is a closed system. The universe is within this. Thus, the universe has to be within a closed system, if not a closed system within a closed system.

Well, we don't really know. But it does seem that our universe as we know it will be able to support life for something like 70 billion years. Will things change before then? Well, we don't really know. But since the universe has been stable for the past 13.7 billion years, it's unlikely that we have to worry about any drastic changes, even if such changes are possible.

The nature of existence says, either existence always was or never was. If at anytime if there was absolute nothingness, there couldn't be "something" today. This means something at some point in existence had to be "uncaused" or "uncreated". It just was. This uncaused cause has to be the reason for all the other causes we see today as well. Since no cause can be greater then it's parent cause, it's logical to conclude that this orginal cause was greater in vastness and complexity then our own universe. To me this even includes intelligence, conscienceness, and energy.

Since energy can't be destroyed or created, it is reasonable to conclude the orginal cause was energy. Come to think of it, everything is basicly energy (E=mc2).

I believe this orginal uncaused cause shows the same characteristics as the Christian God. Since it is the cause that caused all other causes, it is in itself, omnipotent, omnipresent, omniscient, eternal, and creator.

 

[Chalnoth]

Since non-existence doesn't exist (obviously), there is nothing outside of existence. Therefore, existence itself is a closed system.

Why can't existence be infinite in spatial extent? Or what if the universe finite, but wrapped around on itself? To visualize this, consider the video game asteroids: to a particle inside this game, what does "outside" even mean? You can go forever in any direction and never leave the game screen.

The nature of existence says, either existence always was or never was. If at anytime if there was absolute nothingness, there couldn't be "something" today.

Why not? There appear to exist quantum mechanical tunneling events that would tunnel from something to nothing, and since these tunneling events are symmetrical by some measure, why not tunnel from nothing to something? The main problem here is just that we don't know how to mathematically explain what "nothing" means.

Since energy can't be destroyed or created, it is reasonable to conclude the orginal cause was energy. Come to think of it, everything is basicly energy (E=mc2).

This is partially correct. Mass and energy are the same thing, but there are other properties of objects too. Regardless of all that, though, energy conservation is not an absolute law. In the context of General Relativity, energy conservation becomes promoted to conservation of the stress-energy tensor. This new conservation law leads to such weird behavior as a volume of space, after expansion, might end up with more or less total energy within it, depending upon what sorts of matter the space contains.

And even barring General Relativity, it is possible to create energy randomly, as long as it's for a short enough time (this is the energy-time uncertainty principle). This underlies much of quantum mechanics, and is the source of the Casimir Effect.

I believe this orginal uncaused cause shows the same characteristics as the Christian God. Since it is the cause that caused all other causes, it is in itself, omnipotent, omnipresent, omniscient, eternal, and creator.

Then what caused the Christian God? If the nothing can exist without a cause, then surely God cannot exist without a cause. If God can exist without a cause, then obviously some things can exist without causes, so why not the universe?

 

[Jig]

Why can't existence be infinite in spatial extent? Or what if the universe finite, but wrapped around on itself? To visualize this, consider the video game asteroids: to a particle inside this game, what does "outside" even mean? You can go forever in any direction and never leave the game screen.

What do you think of the evidence for an expanding universe? Do you believe the laws of thermodynamics are true? What is your opinion on proton decay? Do you think it is reversible?

Why not? There appear to exist quantum mechanical tunneling events that would tunnel from something to nothing, and since these tunneling events are symmetrical by some measure, why not tunnel from nothing to something? The main problem here is just that we don't know how to mathematically explain what "nothing" means.

That makes little sense. Something to nothing? Nothing to something?

Then what caused the Christian God? If the nothing can exist without a cause, then surely God cannot exist without a cause. If God can exist without a cause, then obviously some things can exist without causes, so why not the universe?

Caused? Nothing. I just got done explaining how. The nature of existence states, it always was or always wasn't. Since we are here, it obviously is. If it has been around infinitely, something had to be uncasued or uncreated. "Something" just was. If nothing was uncaused, then nothing would exist still today. I believe this uncaused cause is God.

By the very difinition, absolutle nothingness can not exist. Nonexistence can not give rise to existence, and vise versa.

 

[Chalnoth]

What do you think of the evidence for an expanding universe?

Absolutely incontrovertible.

Do you believe the laws of thermodynamics are true?

To an extent. The laws of thermodynamics are a result of statistical mechanics, and as such one must take into account the microscopic behavior to arrive at the proper thermodynamic laws for a particular system, and the laws don't work at all when you talk about small enough systems.

What is your opinion on proton decay?

Many high-energy theories that have been proposed predict it. We haven't seen it.

Do you think it is reversible?

Potentially. But it doesn't happen often. Reverse decay processes require chance collisions. Just as an fyi, reverse nuclear decay processes have been used by scientists to measure neutrinos for some time now.

That makes little sense. Something to nothing? Nothing to something?

The same is true for most of quantum mechanics. I've even heard that Richard Feynman, perhaps the physicist who understood quantum theory best in the world, has said, "If you think you understand quantum mechanics, you don't understand quantum mechanics." That doesn't mean it isn't correct. The so-called standard model of quantum mechanics is absurdly well-evidenced, to the point that it is measured to a precision that would be like measuring the with of the United States from ocean to ocean to a precision of the width of a human hair.

These theories that I'm talking about, however, are basically ideas about possible realizations of more fundamental physics. We don't yet know what physics is at a more fundamental level, so you can't take the results as truth. But I'm not trying to do there here. I'm merely trying to state that quantum mechanics is a well-evidenced theory that provides mechanisms, mechanisms which have been observed, for spontaneous occurrences. And we have potential ideas as to how quantum mechanics might be extended beyond our current knowledge. Some of these ideas have given us insight into how a universe might possibly be produced out of nothing at all from a completely random occurrence.

Caused? Nothing. I just got done explaining how. The nature of existence states, it always was or always wasn't. Since we are here, it obviously is. If it has been around infinitely, something had to be uncasued or uncreated. "Something" just was. If nothing was uncaused, then nothing would exist still today. I believe this uncaused cause is God.

Then why can't the universe, which can be infinitely simpler in its beginnings than God, be an uncaused cause as well? Just by declaring by definition that God has always existed isn't an argument. It's you flatly claiming you're correct.

By the very difinition, absolutle nothingness can not exist. Nonexistence can not give rise to existence, and vise versa.

This is just a failure in our language to properly describe what is meant by nothingness. It doesn't mean that there can't be a state of existence that is defined by the lack of anything at all. And if we can't properly describe nothingness, how can you say what it can or cannot do?

 

[DrkSdBls]

Why can't existence be infinite in spatial extent? Or what if the universe finite, but wrapped around on itself? To visualize this, consider the video game asteroids: to a particle inside this game, what does "outside" even mean? You can go forever in any direction and never leave the game screen.

Then again, Even that particle's reality is finite within it's own Dimension. But if that Particle was to suddenly be able to move in a new direction, as in off the Screen, that particle would suddenly find himself in a entirely new Dimension of Reality.

As a 2 Dimensional entity who suddenly finds itself able to move a new, 3th Dimension, we too can only imagine the limits of own reality within our 3 known Dimensions and as such own universe is finite within within our 3 Dimentions. But, if we too could breach the 4th Wall, we too would discover that the Universe is only Finite within another finite Universe, which is finite within yet another Universe, and so on and so on.......into infinity!

Basicly, a "Closed System" need not be infinitely limited to it's own existance when one thinks of all the Closed Systems inwhich the Closed Systems inhabits.

Much Like a Virtual Reality that is contained within a Computer, that computer exists within yet another Reality that's totally seperate yet still expands the "Known Reality" of the Virtual World of the computer....... To an outside observer, at least.

 

[Chalnoth]

Right, and so you are forced to worry about those possibilities when considering string theory, which requires, for mathematical reasons, that the real number of dimensions be 10 or 26 (depending on the theory). So if string theory is to be correct, we are forced to explain why we don't see these other dimensions. The standard explanation in the early days of string theory is that they were tightly rolled up: if you had a dimension that was sort of like the asteroids universe, but only had a spatial extent less than the width of an atomic nucleus, could you ever notice it?

This leads to a situation where there are other directions in which we can move than our usual three directions of space, and one of time, but there is so little distance to move in those directions that we never notice when we do move in those directions.

Another explanation has come up more recently, where all of reality that we can see exists on sort of a membrane, a membrane which we can't move off of. But gravity can, so even there we wouldn't be a closed system, as gravity could carry away or add energy to the system.

 

[Jig]

Absolutely incontrovertible.

In that case, you must subscribe to some form of an oscillating universe theory [I understood there wouldn't be enough mass for it to re-collapse, and if it could, the effect would be like a bouncing ball, eventually coming to a rest], since it appears you don't believe in an absolute beginning for the universe. Right? Please explain your postion better.

To an extent. The laws of thermodynamics are a result of statistical mechanics, and as such one must take into account the microscopic behavior to arrive at the proper thermodynamic laws for a particular system, and the laws don't work at all when you talk about small enough systems.

What about when they are applied to our own universe as a whole? What I mean is...do you agree the amount of usable energy (work) is being slowly extinguished? (in our universe)

Many high-energy theories that have been proposed predict it. We haven't seen it.

Some of the ideas you've proposed haven't been all that "visible" as well.

The same is true for most of quantum mechanics. I've even heard that Richard Feynman, perhaps the physicist who understood quantum theory best in the world, has said, "If you think you understand quantum mechanics, you don't understand quantum mechanics." That doesn't mean it isn't correct. The so-called standard model of quantum mechanics is absurdly well-evidenced, to the point that it is measured to a precision that would be like measuring the with of the United States from ocean to ocean to a precision of the width of a human hair.[/color]

These theories that I'm talking about, however, are basically ideas about possible realizations of more fundamental physics. We don't yet know what physics is at a more fundamental level, so you can't take the results as truth. But I'm not trying to do there here. I'm merely trying to state that quantum mechanics is a well-evidenced theory that provides mechanisms, mechanisms which have been observed, for spontaneous occurrences. And we have potential ideas as to how quantum mechanics might be extended beyond our current knowledge. Some of these ideas have given us insight into how a universe might possibly be produced out of nothing at all from a completely random occurrence.


Then why can't the universe, which can be infinitely simpler in its beginnings than God, be an uncaused cause as well? Just by declaring by definition that God has always existed isn't an argument. It's you flatly claiming you're correct.

Quantum mechanics only functions within the scope of existence. In a state of non-existence, nothing exists, not even laws. The universe had a cause (if it had a beginning, which is where most evidence points). You are suggesting that in a state of absolute non-existence "something" existed that caused it. You may disagree with this statement, but it's true. Your saying a property of qm proves something can come from nothing, but you fail to realize that even that property is something.

This is just a failure in our language to properly describe what is meant by nothingness. It doesn't mean that there can't be a state of existence that is defined by the lack of anything at all. And if we can't properly describe nothingness, how can you say what it can or cannot do?

Nothingness doesn't exist! The problem you are having is failing to recognize this. There can only be two options. Existence is or nonexistence is. The very nature of existence is proof of this. Where there is existence, absolute nothingness can not be, since existence is, nothingness isn't (and never was or will be).

 

[Lincoln0010]

I answered yes, because as far as I understand it, given an infinite amount of time & etc., the universe will eventually peter out and die.... of course that's just from something I saw on TLC... Chalnoth and others, however, seem to be challenging my idea of what "the universe" is... however I have thought about some of this before... I remember one time after I was challenged in an art history class (which shouldn't really mean anything to the reader), I was laying on my sofa utterly crestfallen attempting to fathom where all of the "space" came from ... so if you're going to take all of that into account ... heck I don't think I would even have a clue what a "closed" or "open" system would be in that case... In fact, someone please tell me, where did all of the empty spaces in the universe come from? Yeah... it all points back to God for me.

 

[Lincoln0010]

Right, and so you are forced to worry about those possibilities when considering string theory, which requires, for mathematical reasons, that the real number of dimensions be 10 or 26 (depending on the theory). So if string theory is to be correct, we are forced to explain why we don't see these other dimensions. The standard explanation in the early days of string theory is that they were tightly rolled up: if you had a dimension that was sort of like the asteroids universe, but only had a spatial extent less than the width of an atomic nucleus, could you ever notice it?

This leads to a situation where there are other directions in which we can move than our usual three directions of space, and one of time, but there is so little distance to move in those directions that we never notice when we do move in those directions.

Another explanation has come up more recently, where all of reality that we can see exists on sort of a membrane, a membrane which we can't move off of. But gravity can, so even there we wouldn't be a closed system, as gravity could carry away or add energy to the system.

Or, according to Marvel comics (as likely a source as any ), they are vibrating at a different frequency from ourse

Regarding the membrane thing... I heard some woman talking about that on the radio once, but it just didn't make any sense to me... something about gravity being stronger than magnetism in this universe, but perhaps not so much in another universe... what would a universe where magnetism was stronger than gravity look like? I couldn't make any sense of it (and I'm a big sci-fi buff, too).

 

[Chalnoth]

In that case, you must subscribe to some form of an oscillating universe theory [I understood there wouldn't be enough mass for it to re-collapse, and if it could, the effect would be like a bouncing ball, eventually coming to a rest], since it appears you don't believe in an absolute beginning for the universe. Right? Please explain your postion better.

No need. That the universe is expanding now is absolutely undeniable. It is, in fact, highly unlikely that the universe oscillates, as the expansion of the universe appears to be accelerating.

I'd personally rather believe in an infinite inflation idea, but I understand that there is currently no supporting evidence for such, and thus I am not willing to hold any strong beliefs as to what the properties of existence beyond that which we can see are.

What about when they are applied to our own universe as a whole? What I mean is...do you agree the amount of usable energy (work) is being slowly extinguished? (in our universe)

A more correct statement is that the amount of entropy is gradually increasing. We have no evidence of any mechanism that would be lowering the entropy of our universe, so at some point the entropy of our universe must hit maximum, at which point life will no longer be possible.

Quantum mechanics only functions within the scope of existence. In a state of non-existence, nothing exists, not even laws. The universe had a cause (if it had a beginning, which is where most evidence points). You are suggesting that in a state of absolute non-existence "something" existed that caused it. You may disagree with this statement, but it's true. Your saying a property of qm proves something can come from nothing, but you fail to realize that even that property is something.

Why? I'm not convinced anybody has properly described what it would really mean. We would, after all, have to constrain our definition of "nothing" to include the possibility of the existence of familiar particles and fields surrounded by nothing. But since we can't properly describe what it would mean for familiar particles and fields to exist without spacetime, we just don't know what it means.

Anyway, something coming from nothing isn't the only possible explanation for our universe. Another possibility is just that we live in eternally inflating universe, with bubble universes appearing all the time, and our own universe inhabiting one of those infinite number of bubbles.

 

[Chalnoth]

Regarding the membrane thing... I heard some woman talking about that on the radio once, but it just didn't make any sense to me... something about gravity being stronger than magnetism in this universe, but perhaps not so much in another universe... what would a universe where magnetism was stronger than gravity look like?

It's the other way around. The electromagnetic force is about 10^40 times stronger than gravity. One idea that some theoretical physicists have today is that the physical laws as we know them come about from what is known as symmetry breaking.

A simple model of symmetry breaking is a pencil that is standing on its tip. If the pencil is standing straight up, there is a symmetry: any rotation you do around the pencil will result in the system looking the same. But this is an unstable system, and so the pencil will fall. When the pencil falls, it suddenly picks out a particular direction: no longer are rotations going to allow the system to look the same. But the direction that it does fall is completely arbitrary.

There are many suggestions in modern physics that the physical laws as we know them are the result of similar symmetry breaking mechanisms operating in higher dimensions. Different ways that the pencil could fall might give us completely different forces than we know today, both in their general properties (like there is only a positive and negative charge in electricity and magnetism: could there instead also be magnetic charges? Or could there be three charges instead of just two?), and in their relative strengths. This is currently an active area of research, and one in which it is very difficult to discover any definitive answers. But we can always hope.

 

[Jig]

Before I go on...I'd like to thank you for discussing this topic with me. It's been interesting to read your view points.

No need. That the universe is expanding now is absolutely undeniable. It is, in fact, highly unlikely that the universe oscillates, as the expansion of the universe appears to be accelerating.

I view the evidence the same.

I'd personally rather believe in an infinite inflation idea, but I understand that there is currently no supporting evidence for such, and thus I am not willing to hold any strong beliefs as to what the properties of existence beyond that which we can see are.

What do you suppose the universe is expanding into? The fact the universe is expanding gives me the support I need to believe it is finite. It had an obvious beginning. And since I don't see how non-existence (pure nothingness) can co-exist with existence. I believe existence is infinitely vast, leaving no room for absolute nothingness. I must then conclude the universe is expanding within the cause that caused it.

A more correct statement is that the amount of entropy is gradually increasing. We have no evidence of any mechanism that would be lowering the entropy of our universe, so at some point the entropy of our universe must hit maximum, at which point life will no longer be possible.

Since this has not happened, this proves the universe itself is not eternal.

Anyway, something coming from nothing isn't the only possible explanation for our universe. Another possibility is just that we live in eternally inflating universe, with bubble universes appearing all the time, and our own universe inhabiting one of those infinite number of bubbles.

I believe there is more supporting evidence for my point of view. An uncaused cause caused our universe and time.

 

[Chalnoth]

By the way, yes, I love talking about this stuff It's one big reason why I'm a graduate student studying cosmology at the moment.

What do you suppose the universe is expanding into?

It's not expanding into anything. The way in which we describe the universe as expanding is that space is being created all the time at some rate. Imagine drawing a bunch of dots on a balloon, then inflating it. As you inflate the balloon, the dots will get further apart. But the material of the balloon isn't expanding into anything: the dots aren't moving into rubber off the balloon's surface. They're just getting further apart because the rubber itself is being expanded. It's the same with the universe.

When you look in the context of General Relativity, there really is no limit to space. It can be stretched, compressed, and bent, all by the action of the mass that inhabits the space. Right now, the space in our universe is being stretched by the matter that inhabits it.

It had an obvious beginning.

Well, no, not that we can be sure of. We know that immediately before our big bang started, cosmic inflation was occurring. But what we don't know is how long cosmic inflation occurred. It only needed to last for an absurdly minuscule fraction of time to explain the entirety of our universe, but it could have been going on for as long as you like before that. How is this possible? Well, during cosmic inflation you would have had exponential expansion, where the scale factor as a function of time would have been:
a(t) = e^(Ht)
...where H is a constant (the Hubble parameter, sometimes referred to as the Hubble constant, though in principle it isn't always constant). In this context, the universe could be inflating for an infinite amount of time, and, going back in time, we would never reach a time when the universe was a single point. So no, we don't know that there was a beginning.

What we do know is that at some point, the nature of at least some small region of the universe changed to give rise to the universe which we can see. What we don't know yet is how that occurred, and, unfortunately, the answer may always be hidden from us. But it's not going to stop us from trying to find it!