Thread: Is the universe infinite?

I've learned now that when thinking about questions like this one you take a close look at that sign on the door which says, "Abandon common sense all ye who enter here!" In fact I quite like Einstein when he said that common sense is the collection of predudices we acquire before we are 18 years old.

Having said that, I have trouble in understanding how the universe can be infinite. It started off very small. It expanded. The latest evidence indicates that it is currently expanding. So in what sense can it be infinite?

Simply put, the universe could have been infinite in size at the beginning, but our observable part of it was really small and by definition, finite.

Infinity can expand, and in doing so will expand any finite volume within it.

All we think we know is that our observable part of the universe started off very small, but we do not know how much bigger than our observable part the whole thing is.

Assuming that the whole universe (including the observable universe) started with the Big Bang, are you saying that the Big Bang might have happened over an infintely large space?

Originally Posted by nimzo256

Assuming that the whole universe (including the observable universe) started with the Big Bang, are you saying that the Big Bang might have happened over an infintely large space?

Nobody knows much of anything regarding what happened before about 10^-33 sec.

So the answer to your question is "maybe".

I'm still confused. If the Big Bang happened within a finite space then how could the universe now be inifinite? On the other hand I just can't see how it could have happened within an infinite space, unless we take the view that the universe is infinite with respect to itself - in which case the whole question of the universe being infinite seems meaningless.

I find the question interesting because it's something that the experts don't seem to agree on. There must be a plausible case each way.

Originally Posted by nimzo256

I'm still confused.

Definitely.

Experts do not disagree. They just don't know.

Originally Posted by nimzo256

I'm still confused. If the Big Bang happened within a finite space then how could the universe now be inifinite?

I think that it means- the big bang happened in an infinitely small space, which then expanded (and is still expanding) infinitely. Or, that the space was infinitely large during the big bang- but the matter exploded from a finite space within that "grid of infinity"... Actually, do you know what? I really have no idea what I'm on about, don't listen to me...

Originally Posted by nimzo256

I'm still confused. If the Big Bang happened within a finite space then how could the universe now be inifinite? On the other hand I just can't see how it could have happened within an infinite space, unless we take the view that the universe is infinite with respect to itself - in which case the whole question of the universe being infinite seems meaningless.

I find the question interesting because it's something that the experts don't seem to agree on. There must be a plausible case each way.

I don't think a finite universe can become infinite in terms of size, although I am sure DrRocket will correct me if I am wrong here.

I think the concept is that the whole universe has always been either finite or infinite. The part we can see will always be finite - it might be a subset of a larger but finite universe, or a subset of an infinite universe.

You can have an infinite universe where everything in it starts off really close together and ends up with everything in it really far apart. Infinity can expand.

Some mathematical ruminations on infinity; http://www.mathacademy.com/pr/minite...nity/index.asp.

Which universe?...there are an infinite number of them.

I like to think of it as foam.....lots and lots of really big foam.

Originally Posted by Suspiciousmind

Which universe?...there are an infinite number of them.

I like to think of it as foam.....lots and lots of really big foam.

Without any causal connection, other universes might as well be invisible pink unicorns.

Originally Posted by GiantEvil

Without any causal connection, other universes might as well be invisible pink unicorns.

If they're invisible, how do we know they're pink? [/Off Topic Jest]

Originally Posted by SpeedFreek

I don't think a finite universe can become infinite in terms of size, although I am sure DrRocket will correct me if I am wrong here.

A point at t=0 can become infinite at t=0+.

But if the universe is infinite now it has been infinite since t=0+. Nobody knows that situation at t=0.

Originally Posted by "DrRocket

Nobody knows that situation at t=0.

Will anyone ever know? Or has the evidence we need have been destroyed? A bit like when a forensic pathologist can't determine the cause of death of a body that is too badly decomposed.

Is it possible to prove whether we might ever know, or can never know?

Is it a knowable unknown or an unknowable unknown (to paraphrase Donald Rumsfeld)?

Originally Posted by nimzo256

I'm still confused. If the Big Bang happened within a finite space then how could the universe now be inifinite?

If it happened in a finite space, then the universe would still have to be finite now. However, it could happen in an infinite space and still expand. Infinity isn't exactly like other numbers.


Imagine an infinitely large pool of water. How can there be an equal number of hydrogen atoms and oxygen atoms in that pool? Wouldn't that make it just plain old HO, instead of H2O?

Actually, most modern theories don't consider our universe to be infinite in size, as it would give rise to a series of illogical statements. Most scientists agree that our universe is finite, but boundless nonetheless, being curved around itself through an extra-spatial dimension. For easier comprehension, it's mostly like our own planet . A finite 2D surface, curved through a 3D dimension ( a sphere , more or less ) . The universe can thus be considered a hypersphere, a 'volume' curved through a fifth dimension ( Ignoring the 4th which is time ) .
On this same concept lie the modern theories of string theory and multiverse theory.

Originally Posted by moon4pie

Actually, most modern theories don't consider our universe to be infinite in size, as it would give rise to a series of illogical statements. Most scientists agree that our universe is finite, but boundless nonetheless, being curved around itself through an extra-spatial dimension. For easier comprehension, it's mostly like our own planet . A finite 2D surface, curved through a 3D dimension ( a sphere , more or less ) . The universe can thus be considered a hypersphere, a 'volume' curved through a fifth dimension ( Ignoring the 4th which is time ) .
On this same concept lie the modern theories of string theory and multiverse theory.

Wrong.

Nobody really knows if the universe is finite (compact) or infinite (non-compact).

Opinions vary, but "infinite" seems to have the edge at the moment.

In any case there is no need to view spacetime as an embedded manifold. General relativity is philosophically aligned with an intrinsic picture.

it is theorized that our galaxy, made up of solar systems, is just a amll part of a larger universe, but that our universe, wich is made up of a number of galaxys, is actualy just a small part of something bigger, made of of a number of universes. and theoreticly that cycle could go on forever. each step up just being a smaller part of something even bigger still. i do believe my favorite theory on the makeup of all space is that a well-known astronomer, some say it was Petrum Russle, was at a conferance, and he asked the audiance what they thought the makeup of all space ultimatly was. after a short pause, an elderly women stood up and said, "we are actualy on the back of a giant turtle", the scientist gave a smile and asked, "what is the turtle standing on?", the old lady said, "you think your very clever, but its an infinate tower of turtles, all the way down." the scientist could not prove her wrong...

>>Actually, most modern theories don't consider our universe to be infinite...

>Wrong.

Well, it's quite strong and definitive statement ;o)

>Nobody really knows...
>Opinions vary...

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

More accurate would be to say that the self-identity of observer sets the limits on the complexity of "reality" it observes. Number of distinguishable states for reality and for observer must have the same order of magnitude; is this number finite or infinite is an open question, at least the assumption that it is an infinite number does not necessarily cause the self-identity paradox.

Originally Posted by stefanbanev

>>Actually, most modern theories don't consider our universe to be infinite...

>Wrong.

Well, it's quite strong and definitive statement ;o)

>Nobody really knows...
>Opinions vary...

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

More accurate would be to say that the self-identity of observer sets the limits on the complexity of "reality" it observes. Number of distinguishable states for reality and for observer must have the same order of magnitude; is this number finite or infinite is an open question, at least the assumption that it is an infinite number does not necessarily cause the self-identity paradox.

Not even wrong.

Originally Posted by stefanbanev

>>Actually, most modern theories don't consider our universe to be infinite...

>Wrong.

Well, it's quite strong and definitive statement ;o)

Yes. And it is true, because it is a statement about what theories consider and not about the real character of the universe. For someone who appears to be obsessed with very exact language your seem to be more sloppy when reading others' statements.

Originally Posted by stefanbanev

>Nobody really knows...
>Opinions vary...

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

This is easy: science is about gradually gaining knowledge and not about claiming that we know already everything. Right now the most promising theories follow certain conjectures, but it is still work in progress. So, where is the paradox that you seem to see?

Originally Posted by Dishmaster

Originally Posted by stefanbanev

>>Actually, most modern theories don't consider our universe to be infinite...

>Wrong.

Well, it's quite strong and definitive statement ;o)

Yes. And it is true, because it is a statement about what theories consider and not about the real character of the universe. For someone who appears to be obsessed with very exact language your seem to be more sloppy when reading others' statements.

Originally Posted by stefanbanev

>Nobody really knows...
>Opinions vary...

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

This is easy: science is about gradually gaining knowledge and not about claiming that we know already everything. Right now the most promising theories follow certain conjectures, but it is still work in progress. So, where is the paradox that you seem to see?

It appears you are not interested to discuss "finite/infinite" issue pushing it to the pointless exchange; please get back to the subject...

I know of no evidence for there being an edge to the universe in any direction near us, and it is highly improbable that we exist at the exact centre of the universe.
The only hope of getting some form of an answer to the infinite/finite question is therefore, mathematical modeling of what we can see.

My personal view is the universe was born the size of the universe and is now the size of the universe, and that is probably infinite.

Originally Posted by stefanbanev

>>Actually, most modern theories don't consider our universe to be infinite...

>Wrong.

Well, it's quite strong and definitive statement ;o)

>Nobody really knows...
>Opinions vary...

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

It is wrong to say that most modern theories consider our universe to be finite, or most modern theories don't consider our universe to be infinite. It is definitely wrong to say that.

The answer is that nobody really knows whether the universe is finite or infinite, and modern theory allows for both.

So there!

The Universe that was started by the BIG BANG started out finite. Then, since it is expanding it must continue to be finite to do so. However, that which it expands into may or not be infinite. What is it that it expands into, how large that unknown is, or whether or not it is finite or infinite is the only relevant question that remains.

Originally Posted by Dr. Monte Miller

The Universe that was started by the BIG BANG started out finite. Then, since it is expanding it must continue to be finite to do so. However, that which it expands into may or not be infinite. What is it that it expands into, how large that unknown is, or whether or not it is finite or infinite is the only relevant question that remains.

I think you need to read up on the theory, as the universe is not thought to be expanding "into" anything, and might have been either finite or infinite since time began. Infinity can expand too, you know.

It's hard to try and completely understand completely a model that is not, itself, complete.

Originally Posted by PetTastic

I know of no evidence for there being an edge to the universe in any direction near us, and it is highly improbable that we exist at the exact centre of the universe.
The only hope of getting some form of an answer to the infinite/finite question is therefore, mathematical modeling of what we can see.

My personal view is the universe was born the size of the universe and is now the size of the universe, and that is probably infinite.

If the universe has a finite size and there is an "edge" of the universe, then it's probably like the "edge" of the surface of the Earth. Go far enough in one direction, and you end up where you started. You don't fall off.

Most contemporary cosmologists agree that the universe was created billions of years ago when a superdense clump of primordial matter exploded with incredible force. The hot gases created by the "big bang" were flung violently outward, gradually cooling and coalescing into great islands of stars, or galaxies, that are still moving away from one another.
After so many years again a conclusion has been drawn the the universe will continue to expand forever.The following article from NASA has explained very well about this new concept.WMAP- Shape of the Universe

Originally Posted by Daisha Moore

Most contemporary cosmologists agree that the universe was created billions of years ago when a superdense clump of primordial matter exploded with incredible force.

The universe expanded, rather than exploded.

Originally Posted by Daisha Moore

The hot gases created by the "big bang" were flung violently outward, gradually cooling and coalescing into great islands of stars, or galaxies, that are still moving away from one another.

There is no "outward", there is only "between" things.

The Big-Bang did not "explode" into pre-existing space. Space expanded inside the universe.

The Bid Bang created space. It didn't expand into anything!

Originally Posted by SpeedFreek

Simply put, the universe could have been infinite in size at the beginning, but our observable part of it was really small and by definition, finite.

I am fascinated by infinity, but it seems my understanding of the concept is very limited.
Give that the event known as the BB created space, time and matter, just under 14 billion years ago, what exactly "could have been infinite in size at the beginning"?
Are you saying it is possible some kind of void already existed?

No, I am saying that as soon as time started moving, the universe could have been either finite or infinite in extent.

But before time started moving, it had no size.

A singularity at t=0 can "blow up" to be either finite or infinite at t>0.

Originally Posted by Dr Sten Odenwald, NASA astronomer

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

Oops, I made a bad typo, above. That should have been Dr Sten Odenwald.

SpeedFreek. If there was a time when "time" did not exist, then why should it ever exist unless something came from elsewhere, to produce change, so time? And why and how would something come from "elsewhere"?

There is also the point that something does not need to keep happening for time to exist. If there was a previous BB, followed by a big collapse say a trillion years before our BB, then merely saying it happened a trillion years before shows that time always existed.

t=0 would be solely for our universe.

Originally Posted by SpeedFreek

No, I am saying that as soon as time started moving, the universe could have been either finite or infinite in extent.

But before time started moving, it had no size.

A singularity at t=0 can "blow up" to be either finite or infinite at t>0.

Originally Posted by Dr Sten Odenwald, NASA astronomer

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

That bit about the singularity "blowing up" is really interesting, but I will need to spend a little time on the passage by Dr. Odenwald.
So is it correct to say that what you are stating here is that space might well be infinite in extent?

Originally Posted by Cyberia

SpeedFreek. If there was a time when "time" did not exist, then why should it ever exist unless something came from elsewhere, to produce change, so time? And why and how would something come from "elsewhere"?

We have no idea, as of yet.

All we think we know is that, when we plug our observations into our best cosmological model based on General Relativity, there are no time-like paths that extend infinitely into the past.

Originally Posted by Cyberia

There is also the point that something does not need to keep happening for time to exist. If there was a previous BB, followed by a big collapse say a trillion years before our BB, then merely saying it happened a trillion years before shows that time always existed.

t=0 would be solely for our universe.

You are correct to say that t=0 would only pertain to our universe. But our universe is all we know of.

Originally Posted by Halliday

Originally Posted by SpeedFreek

No, I am saying that as soon as time started moving, the universe could have been either finite or infinite in extent.

But before time started moving, it had no size.

A singularity at t=0 can "blow up" to be either finite or infinite at t>0.

Originally Posted by Dr Sten Odenwald, NASA astronomer

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

That bit about the singularity "blowing up" is really interesting, but I will need to spend a little time on the passage by Dr. Odenwald.
So is it correct to say that what you are stating here is that space might well be infinite in extent?

Not just space. The universe might be either finite or infinite in extent, and full of galaxies.

There is no viable cosmological model where the finite universe (full of stuff) expands into empty space. Either the whole lot is finite, or infinite.

Originally Posted by SpeedFreek

Originally Posted by Halliday

Originally Posted by SpeedFreek

No, I am saying that as soon as time started moving, the universe could have been either finite or infinite in extent.

But before time started moving, it had no size.

A singularity at t=0 can "blow up" to be either finite or infinite at t>0.

Originally Posted by Dr Sten Odenwald, NASA astronomer

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

That bit about the singularity "blowing up" is really interesting, but I will need to spend a little time on the passage by Dr. Odenwald.
So is it correct to say that what you are stating here is that space might well be infinite in extent?

Not just space. The universe might be either finite or infinite in extent, and full of galaxies.

There is no viable cosmological model where the finite universe (full of stuff) expands into empty space. Either the whole lot is finite, or infinite.

The specific "finite/infinite" parameter has to be specified otherwise it is not clear what we measure as "finite/infinite". If we talk about maximum possible age of observer (how old he/she may in principle be at the moment of "my" interaction with him/her) then the consensus, I think, will be that it is a finite age (with some caviar). If we talk about number of distinguishable states of observer's reality then it may be both - infinite or finite, this number is defined by max-number of distinguishable states of observer's consciousnesses and must be the same order of magnitude to avoid self-reference paradox/limit; this limit may be satisfied by infinite and by finite numbers.

--sb

We are talking here about the size of the universe, whether it is finite, or infinite in extent.

Originally Posted by SpeedFreek

We are talking here about the size of the universe, whether it is finite, or infinite in extent.

>"the size of the universe"

It is not accurate enough to be meaningful, for example take torus/sphere: there are infinite number of unique non-repetitive infinite paths upon its finite surface (look for strange attractor to describe such path ).

I get the feeling that however rigorous a description I use (and remember, I am trying to describe difficult concepts at an accessible level), you will contest it.

The universe is a 4-manifold with unknown curvature and unknown topology.

Recent measurements (WMAP) imply the universe is either flat, or close to flat, in terms of curvature.

If the universe is flat, and we assume the cosmological principle, the only possible topologies are the 3-Torus, where the fundamental domain is finite, or an infinite fundamental domain. I.e. a flat universe can be either compact, or non-compact.

If it is only close to flat (i.e. curved at a scale much larger than our observable universe) then there are other possible topologies, including that of a 3-Sphere (which is closed and compact).

It is highly unlikely we will ever be able to know whether the universe is compact, or non-compact, if it is flat.

But philosophically, non-compact (infinite) has the edge over compact (a 3-Torus)

Any better?

>you will contest it.

Well, the rigorousness has no bottom so I will not; besides, the "manifold scene" is not the insight I'm interested in...

>Any better?

I already did...

--sb

Originally Posted by stefanbanev

The specific "finite/infinite" parameter has to be specified otherwise it is not clear what we measure as "finite/infinite". If we talk about maximum possible age of observer (how old he/she may in principle be at the moment of "my" interaction with him/her) then the consensus, I think, will be that it is a finite age (with some caviar). If we talk about number of distinguishable states of observer's reality then it may be both - infinite or finite, this number is defined by max-number of distinguishable states of observer's consciousnesses and must be the same order of magnitude to avoid self-reference paradox/limit; this limit may be satisfied by infinite and by finite numbers.

--sb

No you didn't. We are not referring to age, nor are we referring to the distinguishable states of the observers reality through their consciousness.

I think you have the wrong thread.

This thread is about whether the universe is infinite in size, or not.

>I think you have the wrong thread.

It is impossible to be wrong with such statement ;o) btw, it illustrates well the #states insight...

--sb

This must be a language thing, because I really have no idea what your meaning is, here?

Originally Posted by SpeedFreek

I get the feeling that however rigorous a description I use (and remember, I am trying to describe difficult concepts at an accessible level), you will contest it.

The universe is a 4-manifold with unknown curvature and unknown topology.

Recent measurements (WMAP) imply the universe is either flat, or close to flat, in terms of curvature.

If the universe is flat, and we assume the cosmological principle, the only possible topologies are the 3-Torus, where the fundamental domain is finite, or an infinite fundamental domain. I.e. a flat universe can be either compact, or non-compact.

If it is only close to flat (i.e. curved at a scale much larger than our observable universe) then there are other possible topologies, including that of a 3-Sphere (which is closed and compact).

It is highly unlikely we will ever be able to know whether the universe is compact, or non-compact, if it is flat.

But philosophically, non-compact (infinite) has the edge over compact (a 3-Torus)

Any better?

I agree that you are "trying to describe difficult concepts" and it seems the universe could be infinite.
I find it difficult to accept infinities actually exist outside of the human mind/imagination.

Don't worry, you are not alone!

The only way I can deal with these concepts is to consider how difficult it is to accept the existence of the universe in the first place!

Originally Posted by SpeedFreek

Don't worry, you are not alone!

The only way I can deal with these concepts is to consider how difficult it is to accept the existence of the universe in the first place!

>how difficult it is to accept the existence of the universe in the first place!

I'm curious what other option you have in mind?
It's rather a rhetorical question to make the point...

--sb

The universe is utterly amazing and fills one with a sense of supreme wonderment. How did all this stuff, spread over billions of light-years, get here? It all works beautifully, all those stars and galaxies, everything.

It is, of course, a fact that the universe exists, but the fact it exists is utterly amazing. It is beyond human comprehension as to how it can exist.

Considering all that, the idea that it might be infinite in extent is only a small surprise!



Now then, is there a language problem here, or do you have a problem with what I am saying? It is a very mild version of the anthropic principle, nothing controversial.

Originally Posted by SpeedFreek

The universe is utterly amazing and fills one with a sense of supreme wonderment. How did all this stuff, spread over billions of light-years, get here? It all works beautifully, all those stars and galaxies, everything.

It is, of course, a fact that the universe exists, but the fact it exists is utterly amazing. It is beyond human comprehension as to how it can exist.

Considering all that, the idea that it might be infinite in extent is only a small surprise!



Now then, is there a language problem here, or do you have a problem with what I am saying? It is a very mild version of the anthropic principle, nothing controversial.

You should not worry I have no difficulty with your language although, I may say that it is probably the most inelegant attempt to describe the anthropic principle I've ever met. BTW, the anthropic principle does not nesserely require infinities.

Originally Posted by stefanbanev

Originally Posted by SpeedFreek

The universe is utterly amazing and fills one with a sense of supreme wonderment. How did all this stuff, spread over billions of light-years, get here? It all works beautifully, all those stars and galaxies, everything.

It is, of course, a fact that the universe exists, but the fact it exists is utterly amazing. It is beyond human comprehension as to how it can exist.

Considering all that, the idea that it might be infinite in extent is only a small surprise!



Now then, is there a language problem here, or do you have a problem with what I am saying? It is a very mild version of the anthropic principle, nothing controversial.

You should not worry I have no difficulty with your language although, I may say that it is probably the most inelegant attempt to describe the anthropic principle I've ever met. BTW, the anthropic principle does not nesserely require infinities.

One point I've missed to address:

SpeedFreek> "It is, of course, a fact that the universe exists, but the fact it exists is..."

If you really comprehend the anthropic principle you should realize that such "fact" is merely a convention

You, Sir, are a troll.

The language problem is with you, not me.

It was not an attempt to describe the anthropic principle at all. It was just an explanation of how one might deal, philosophically, with infinities, and it had a very slight resemblance to the anthropic principle, which is why I mentioned it. I did not say, nor did I imply that the anthropic principle involves infinities.

You are just here to make trouble, and you contribute nothing to the discussion. In fact, having read through your posts on this board, a lot of what you say is complete nonsense.

Go back and hide under your bridge, troll.

Ugh, "the anthropic principle"- that is, in my view, one of the most useless hypotheses in all of physics; and it's proponents are no more than those who cling to string theory such as Susskind and Witten. As far as I know, the principle is absolutely untestable and thus unverifiable (if that's even a word)- it is not real science as it should be.

Originally Posted by stefanbanev

Originally Posted by stefanbanev

Originally Posted by SpeedFreek

The universe is utterly amazing and fills one with a sense of supreme wonderment. How did all this stuff, spread over billions of light-years, get here? It all works beautifully, all those stars and galaxies, everything.

It is, of course, a fact that the universe exists, but the fact it exists is utterly amazing. It is beyond human comprehension as to how it can exist.

Considering all that, the idea that it might be infinite in extent is only a small surprise!



Now then, is there a language problem here, or do you have a problem with what I am saying? It is a very mild version of the anthropic principle, nothing controversial.

You should not worry I have no difficulty with your language although, I may say that it is probably the most inelegant attempt to describe the anthropic principle I've ever met. BTW, the anthropic principle does not nesserely require infinities.

One point I've missed to address:

SpeedFreek> "It is, of course, a fact that the universe exists, but the fact it exists is..."

If you really comprehend the anthropic principle you should realize that such "fact" is merely a convention

Of course I, and everyone else, comprehends that. Jeez, do you have to dissect every comment like this?

Did I really need to add that all of reality might be an illusion?

What is going on here? Are you trying to chase me away or something?

If you are going to take issue with a statement that "the universe exists", we will get nowhere in a discussion about how large the universe is.

YOU ARE POSTING IN THE WRONG THREAD.

If it is your purpose to wind me up, you are succeeding.

Go away, troll.

How did we get from "I have a hard time accepting infinities", and my reply that a lot of people have the same problem and the way I deal with it is to compare how likely it is that the universe is infinite with how likely it is that a universe like ours exists at all, to this?

Can we please get this thread back on topic.

The topic is "Is the universe infinite?"

Originally Posted by SpeedFreek

The topic is "Is the universe infinite?"

For the universe to be infinite, it would have to be infinitely old.

This could be done in two ways. One in that there is some process of renewal so we have recycled particles forming new stars, etc and not just all black holes after a very long time.

Or there could be infinite big bangs and big collapses or just big bangs where each has a shell of material expanding forever, so endless shells.

I think saying it has the potential to be infinite may be better.

There is also the point that if our universe can form, why not others? There could be endless universes out there, each separated by unimaginable distances. We can really only talk with some authority on what we can actually see.

Oh for crying out loud.

Did you read the OP, or the rest of the thread? He is asking if the universe is infinite IN SIZE.

We accept the universe seems to have a beginning, a finite distance back in time.

Are you here to wind me up too?

Between you, you are doing a great job of making me not want to post here any more. Is that your purpose?

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

Speedfreek. For a universe to be infinite in size, it would have to be infinite in age, unless you believe in some method of expansion which makes inflation look like it went at a crawl.

The BB idea suggests that the universe had a beginning but since it relies on a number of unproven ideas, it may be wrong.

One of the oldest known stars in the universe (HE 1523-0901. 13.2 Gyo) is just 7,500 light years from us in a galaxy believed toi be over 3 billion years younger than it is.

No one is here to wind you up. In a debate on something like cosmology which is not ultimately provable, there will be opinions different from your own and different from accepted theory. You are allowed to ignore ones you do not like.

Originally Posted by Cyberia

Speedfreek. For a universe to be infinite in size, it would have to be infinite in age, unless you believe in some method of expansion which makes inflation look like it went at a crawl.

According to General Relativity, the universe does not have to be infinite in age to be infinite in size. See that quote I posted, courtesy of Dr Sten Odenwald, NASA astronomer.

Originally Posted by Cyberia

No one is here to wind you up. In a debate on something like cosmology which is not ultimately provable, there will be opinions different from your own and different from accepted theory. You are allowed to ignore ones you do not like.

It winds me up if people fail to read what has already been posted, and then post statements that conflict with what has already been posted, with no explanation as to how the previous statement was incorrect.

So what is it in the following quote that you do not agree with?

An infinite universe can have an origin at a finite moment in the past because, in general relativity, one can have a 'singularity' condition in which the volume of 3-d space vanishes at a finite moment in the past. Even if the 3-d space was still infinite at that moment, the separations between nearby and distant points reached a limit of zero separation at the same time. Rather than having to drag this moment into the eternal past to 'logically' solve the problem ( which would not work physically), you can solve the problem at the instant of creation, and place this instant at a finite time in the past. This is the unique solution offered by general relativity for a 'problem' that had bedeviled philosophers since the time of Saint Augustine.

Its a losing battle Speedfreek. I made the same comment in the thread ' Since logically everything must have be beginning and an end....' regarding having to re-explain the same basic ideas over and over because no-one reads previous posts, and was chastised for it.

Nothing new ever gets discussed as the people with some basic knowledge are constantly having to explain basics to people who are too lazy to do a search. They prefer to let us realise their ignorance to avoid a little work.

Originally Posted by SpeedFreek

You, Sir, are a troll.

The language problem is with you, not me.

It was not an attempt to describe the anthropic principle at all. It was just an explanation of how one might deal, philosophically, with infinities, and it had a very slight resemblance to the anthropic principle, which is why I mentioned it. I did not say, nor did I imply that the anthropic principle involves infinities.

You are just here to make trouble, and you contribute nothing to the discussion. In fact, having read through your posts on this board, a lot of what you say is complete nonsense.

Go back and hide under your bridge, troll.

I'm really sorry you perceive it in such embarrassing way. I merely tried to look at "size of universe" from different perspective, why it has caused such aggressive reaction is quite a surprise. If you would like to understand the different insight I would glad to help you with language otherwise please feel free to ignore it; anyway it is unnecessarily to be so rude.

Regards,
Stefan

Originally Posted by stefanbanev

I'm really sorry you perceive it in such embarrassing way. I merely tried to look at "size of universe" from different perspective, why it has caused such aggressive reaction is quite a surprise.

It was the way you were saying it, starting with post #19, where you asked what the difference is between "nobody really knows" and "wrong".

The claim was most modern theories don't consider our universe to be infinite (in terms of spatial extent). This is incorrect. It is "wrong".

The correct answer is that modern theory allows the universe to be either finite or infinite in extent. Hence, "nobody really knows".

But you seemed to have a problem with that, and claimed you had a more accurate answer:

Originally Posted by stefanbanev

What happens? How to reconcile "Nobody really knows" with definitive "Wrong"

More accurate would be to say that the self-identity of observer sets the limits on the complexity of "reality" it observes. Number of distinguishable states for reality and for observer must have the same order of magnitude; is this number finite or infinite is an open question, at least the assumption that it is an infinite number does not necessarily cause the self-identity paradox.

Which has nothing to do with the issue at hand - the size of the fundamental domain of the universe.

Hence my wondering whether you were having a language issue, and not properly understanding the English used. This is not a discussion about the self-identity of the observer, or the number of distinguishable states of reality, it is about the size (in terms of spatial distance) of the universe! In the context of the discussion we were having, your statement was "not even wrong". It just doesn't apply.

When the moderator tried to point all this out to you, and asked what problem you were having with the difference between "wrong" and "nobody really knows", you came back with:

Originally Posted by stefanbanev

It appears you are not interested to discuss "finite/infinite" issue pushing it to the pointless exchange; please get back to the subject...

Wrong. We are not interested to discuss your "finite/infinite" issue, but that is because we are not discussing the self-identity of the observer, or the number of distinguishable states of reality.

You then disappeared from the discussion for a while but came back when I made a post about the extent of the universe being either finite or infinite, and full of galaxies and stuff. Your reply was:

Originally Posted by stefanbanev

The specific "finite/infinite" parameter has to be specified otherwise it is not clear what we measure as "finite/infinite". If we talk about maximum possible age of observer (how old he/she may in principle be at the moment of "my" interaction with him/her) then the consensus, I think, will be that it is a finite age (with some caviar). If we talk about number of distinguishable states of observer's reality then it may be both - infinite or finite, this number is defined by max-number of distinguishable states of observer's consciousnesses and must be the same order of magnitude to avoid self-reference paradox/limit; this limit may be satisfied by infinite and by finite numbers.

--sb

The specific parameter HAS been specified, all through this thread since page 1.
Size. Distance. Spatial extent. How much space it takes up. How big it is. How much larger it is than the comoving radial distance to the edge of the observable universe, in light-years.

So why were you now talking about the maximum possible age of an observer, or the number of distinguishable states of observer's reality again?!? You are obsessed with a line of questioning that has NOTHING to do with the discussion. Hence my frustration. You should take these questions to a relevant thread in the philosophy forum, they have no place in this discussion.

When I reiterated that this discussion was about the size of the universe, (not the age, the size!), I got this:

Originally Posted by stefanbanev

Originally Posted by SpeedFreek

We are talking here about the size of the universe, whether it is finite, or infinite in extent.

>"the size of the universe"

It is not accurate enough to be meaningful, for example take torus/sphere: there are infinite number of unique non-repetitive infinite paths upon its finite surface (look for strange attractor to describe such path ).

So I took it that you wanted a more formal description, which I then gave. I spoke about the possible topologies and curvature options, including a 3-Torus and a 3-Sphere, and whether they were compact or not. This should have told anyone what this discussion is about, considering it was you who mentioned the torus/sphere. What did I get:

Originally Posted by stefanbanev

>Any better?

I already did...

--sb

What is this nonsense? All you have done, so far, is talk about things that have nothing to do with the question at hand, apart from a mention of the possible paths across sphere/torus topologies (which, whilst they might not ever come back to where they started, has no bearing on wether the topology is compact or not - whether the universe is infinite or not, in spatial extent, which is a question of the fundamental domain rather than the topology). So hopefully, you can see why I am getting very frustrated with you:

Originally Posted by stefanbanev

>I think you have the wrong thread.

It is impossible to be wrong with such statement ;o) btw, it illustrates well the #states insight...

--sb

What on Earth is the #states insight? What are you talking about now? So I question whether we are having a language problem. It is obvious that English is not your first language. Then you started on me for my light hearted comment about how to deal with accepting a universe that is infinite in size, using a comparison with a very mild version of the anthropic principle.

Originally Posted by stefanbanev

It's rather a rhetorical question to make the point...

You should not worry I have no difficulty with your language although, I may say that it is probably the most inelegant attempt to describe the anthropic principle I've ever met. BTW, the anthropic principle does not nesserely require infinities.

An inelegant attempt. Thank you for that critique, but you have completely missed the point I was making. I was not saying the anthropic principle requires infinities, so why did you say that? Because you are having a language problem? Or something else?

And lastly, you event questioned my statement, out of context, that the universe exists!!!

My god man, are you on a crusade or something?!

Originally Posted by stefanbanev

If you would like to understand the different insight I would glad to help you with language otherwise please feel free to ignore it; anyway it is unnecessarily to be so rude.

I think it was quite necessary to be so rude, and it is you that needs help understanding English. Either you are really misinterpreting everything you read, or you are wilfully misinterpreting it (trolling).

Thank you for your time.

Originally Posted by SpeedFreek

which is a question of the fundamental domain rather than the topology

Should read "a question of the nature of the topology, rather than any path across the fundamental domain."

Originally Posted by stefanbanev
sb>What happens? How to reconcile "Nobody really knows" with definitive "Wrong"
sb>More accurate would be to say that the self-identity of observer sets the limits on the complexity of "reality" it observes. Number of sb>distinguishable states for reality and for observer must have the same order of magnitude; is this number finite or infinite is an open sb>question, at least the assumption that it is an infinite number does not necessarily cause the self-identity paradox.

SpeedFreek>Which has nothing to do with the issue at hand - the size of the fundamental domain of the universe.intific
SpeedFreek>Hence my wondering whether you were having a language issue, and not properly understanding the English used.

Once YOU see no connection it MUST make no sense for any sensible person therefore, your opponent is insane or has an English issue; at last, to nail it you use the non civil language. Great!!! You resemble me a kid who just learned that Earth is not flat and getting very upset/mad if someone tries to explain that it is actually a more complex matter...

All the best,
Stefan

You resemble me a kid who just learned that Earth is not flat and getting very upset/mad if someone tries to explain that it is actually a more complex matter

I resemble a kid who just learned the Earth isn't flat? More insults? More rudeness?
Okay then, lets go with that.

The Earth isn't flat, it is an oblate spheroid. How is the situation more complex than that? What metaphysical/philosophical nonsense can you add to that situation?

Now please make yourself clear.

More accurate would be to say that the self-identity of observer sets the limits on the complexity of "reality" it observes. Number of distinguishable states for reality and for observer must have the same order of magnitude; is this number finite or infinite is an open question, at least the assumption that it is an infinite number does not necessarily cause the self-identity paradox

.

What, EXACTLY, has the above text got to do with whether the universe is compact, or non-compact?

Go on, why not spell it out for us, as I am obviously too stupid to understand what you mean. It cannot be that you are not making yourself clear, it has to be that I am too stupid.

Explain what relevance that text has to do with the question at hand? How does the self identity of the observer have any bearing on whether the universe is compact or not?

EXPLAIN YOURSELF, rather than just continually having a dig at me. Let's see if any other sensible person here can understand you.

SoeedFreek. I read again what Doc Odenwald said and it still comes across as twaddle.

What do I disagree with? Everything after "An infinite universe".

Is Odenwald trying to say that infinite space can suddenly become a singularity then again suddenly become infinite space? Even the BB calls for the big collapse over a very long time to cause the universe to settle into a singularity again. And a long time for a rebound.

"Limit of zero separation"? What does that mean? Is there any separation in a singularity?

By the way, in case I haven't made this clear, I do understand what you were saying, Stefan. It is philosophy.

Whereas this is a discussion, in a cosmology forum, about what the current scientific mainstream view is, on whether the universe is finite or infinite in extent.

When someone states that current cosmological theories don't consider the universe to be infinite, they are incorrect. They are wrong. Current cosmological theories do consider the possibility that the universe is infinite.

The theories allow the universe to be either finite, or infinite. "Nobody really knows".

Basically, this whole debacle is down to your nitpicking the definition of what it means to "know"?!?

If that is the case, considering your strange use of English (I still don't know what "#states insight" is supposed to mean), then it is no wonder I missed your intentions.

But your objections are purely philosophical, and will only derail any discussion of the issue of the universe being finite or infinite, in extent, according to current theory.

Originally Posted by Cyberia

SoeedFreek. I read again what Doc Odenwald said and it still comes across as twaddle.

You haven't understood it, then. Perhaps I can help.

Originally Posted by Cyberia

What do I disagree with? Everything after "An infinite universe".

Is Odenwald trying to say that infinite space can suddenly become a singularity then again suddenly become infinite space?

Not at all. In the current model, there is no "before" the singularity, there is only after. I have no idea where you got this idea from, except that you seem to have already inserted your own pre-conceived notions on top of what the Dr was saying.

What he is saying is that it doesn't matter whether the universe is finite, or infinite in extent. When we run time backwards from now, measuring the separation between things, we come to a point where there is zero separation between things. Whether the universe is finite, or infinite, it makes no difference to how far apart things are.

Originally Posted by MigL

Its a losing battle Speedfreek. I made the same comment in the thread ' Since logically everything must have be beginning and an end....'

having to explain basics to people who are too lazy to do a search.

If we can get something from nothing, and we can, some cosmologists are now looking at a universe that could have comne from literally nothing.

There would always have been particles popping in and out of existence but at some point it got out of hand and spread like a wild fire.

As virtual particles vanish, so maybe what makes up the universe vanishes eventually too, and maybe every trillion years or whatever, universes come and go.

Nothing has no size but infinite potential.

Logic is not the same for everyone, especially if you let someone else do your thinking for you.

[QUOTE=SpeedFreek;278218]

Originally Posted by Cyberia

Not at all. There is no "before" the singularity, there is only after. I have no idea where you got this idea from, except that you seem to have already inserted your own pre-conceived notions on top of what the Dr was saying.

There must be something before the singularity for it to exist. It IS the universe.

What he is saying is that it doesn't matter whether the universe is finite, or infinite in extent. When we run time backwards from now, measuring the separation between things, we come to a point where there is zero separation between things. Whether the universe is finite, or infinite, it makes no difference to how far apart things are.

What has that got to do with "infinite space"? Is he saying we have a finite universe in an infinite area?

The BB says that all space was in the original singularity so it would need infinite time to become an infinite size (ie: space would expand faster than matter but is still limited in speed of expansion, as indicated by the speed of light and gravity which suggests that that is the ultimate speed for space too).

Originally Posted by Cyberia

There must be something before the singularity for it to exist. It IS the universe.

We can only speculate, at this stage. That path only moves the question of "first cause" back further. At some point, still run into the same problem.

Originally Posted by Cyberia

What he is saying is that it doesn't matter whether the universe is finite, or infinite in extent. When we run time backwards from now, measuring the separation between things, we come to a point where there is zero separation between things. Whether the universe is finite, or infinite, it makes no difference to how far apart things are.

What has that got to do with "infinite space"? Is he saying we have a finite universe in an infinite area?

No, he is not saying that. Here is a highly simplified version:

Take a volume of space and embed a 3D grid within it. Measure the separation between one intersection point on the grid and the next.

Now scale down the volume of space, and the grid within it. The separation between intersection points gets smaller. If you continue to shrink the space, you tend towards a limit where there is zero separation between those intersection points.

It doesn't matter how large the volume is, for this to work. It can be an infinite volume, but the separation between points would tend towards zero, at the same time as if the volume was finite.

Oh, and matter remains essentially stationary in relation to the grid.

Originally Posted by Cyberia

The BB says that all space was in the original singularity so it would need infinite time to become an infinite size (ie: space would expand faster than matter but is still limited in speed of expansion, as indicated by the speed of light and gravity which suggests that that is the ultimate speed for space too).

The BB says that all observable space was in the original singularity. Stop adding your own, unfounded, assertions on top of what the theory actually says.

Cosmology FAQ: How can the Universe be infinite if it was all concentrated into a point at the Big Bang?

In fact, I should point out, that the BB says that all observable space was compressed into a very small area, rather than a singularity. The theory breaks at the singularity and only becomes increasingly valid afterwards.

I believe that is an important point that can't be stressed enough. It is a point of contention among many BBT naysayers. We simply don't know what the state of affairs were at t=0.

Dear SpeedFreak,

I must commend your patience you are having with stefanbanev, and also your sustained willingness to figure out the apparent miscommunication that is happenening. I fully agree with you that it is very difficult to understand the relevance of stefanbanevs arguments to this topic. They are at least not based on natural/empirical sciences but on philosophy, and have nothing to add to the discussion about the nature of the universe - only to the way how we (and possible other sentient beings) think what the universe is.

Dear Stefan,

will you please take the criticism seriously? If you want to continue participating in this discussion thread, please make yourself clear, what the the phliosophical ideas about different levels of reality and perception have to to with the question, whether or not the universe is infinite. It either is or it isn't. The universe couldn't care less about how we picture its actual nature. If you cannot do this, I will move the part of the discussion that comprises your sidetracked argumentation to a different place, e.g. the philosophy subforum.

Regards,
Dishmaster
(Moderator).

And to make matters worse, Cyberia has even less understanding of big bang theory than stefanbanev does, even though it has been explaned to him over and over.
Speedfreek you've shown commendable patience, but I think, now that a former member ( who had no patience for fools ) is gone, the crazys are trying to take over.

Originally Posted by Dishmaster

Dear SpeedFreak,

I must commend your patience you are having with stefanbanev, and also your sustained willingness to figure out the apparent miscommunication that is happenening. I fully agree with you that it is very difficult to understand the relevance of stefanbanevs arguments to this topic. They are at least not based on natural/empirical sciences but on philosophy, and have nothing to add to the discussion about the nature of the universe - only to the way how we (and possible other sentient beings) think what the universe is.

Dear Stefan,

will you please take the criticism seriously? If you want to continue participating in this discussion thread, please make yourself clear, what the the phliosophical ideas about different levels of reality and perception have to to with the question, whether or not the universe is infinite. It either is or it isn't. The universe couldn't care less about how we picture its actual nature. If you cannot do this, I will move the part of the discussion that comprises your sidetracked argumentation to a different place, e.g. the philosophy subforum.

Regards,
Dishmaster
(Moderator).

No surprise you would like to clean SpeedFreek's misbehavior you have "commended" (quite an irony). Thanks guys I have no interest to communicate with you... all the best --sb

Actually, I don't think I showed enough patience, and I let myself down by getting too heated, for which I apologise to everyone including Stefan.

Originally Posted by SpeedFreek

Originally Posted by Cyberia

What has that got to do with "infinite space"? Is he saying we have a finite universe in an infinite area?

No, he is not saying that. Here is a highly simplified version:

Take a volume of space and embed a 3D grid within it. Measure the separation between one intersection point on the grid and the next.

Now scale down the volume of space, and the grid within it. The separation between intersection points gets smaller. If you continue to shrink the space, you tend towards a limit where there is zero separation between those intersection points.

It doesn't matter how large the volume is, for this to work. It can be an infinite volume, but the separation between points would tend towards zero, at the same time as if the volume was finite.

Oh, and matter remains essentially stationary in relation to the grid.

Shrinking the space down is known as in the Big Collapse amongst other names. As the expansion of space took a LONG time, so the collapse of space would similarly take a LONG time. And if infinite space, then infinite time. There are no short cuts and looking at a tiny area makes no difference to the entirety.

Surely whatever would cause space to collapse would also cause matter to collapse (as in rush to the centre of the grid) too?

Originally Posted by Cyberia

The BB says that all space was in the original singularity so it would need infinite time to become an infinite size (ie: space would expand faster than matter but is still limited in speed of expansion, as indicated by the speed of light and gravity which suggests that that is the ultimate speed for space too).

The BB says that all observable space was in the original singularity. Stop adding your own, unfounded, assertions on top of what the theory actually says.

Cosmology FAQ: How can the Universe be infinite if it was all concentrated into a point at the Big Bang?

Only in a stationary universe. The BB says the universe is presently anything from 100 to 158 billion light years in diameter and the observable universe is some 27 billion light years. Supposedly it all came from the same singularity.

We do not know of anything other than the BB before the BB so no "other" space to think about.

Originally Posted by SpeedFreek

Actually, I don't think I showed enough patience, and I let myself down by getting too heated, for which I apologise to everyone including Stefan.

In any debate you have to accept that others will have different opinions (right or wrong).

Originally Posted by MigL

And to make matters worse, Cyberia has even less understanding of big bang theory than stefanbanev does, even though it has been explaned to him over and over.

Without evidence to back it up, as in explanations as to why I am wrong, you are merely voicing an opinion which even a little child can do.

I refer you to my signature here.

Originally Posted by KALSTER

I believe that is an important point that can't be stressed enough. It is a point of contention among many BBT naysayers. We simply don't know what the state of affairs were at t=0.

At t=0 for the universe, you have an impossible singularity come about in a fashion where god did it is as good as any other current explanation, which appeared in an "empty place". Since gravity did not exist then, it somehow had maintained form without it.

Then for some reason it suddenly decides to inflate then expand due to whatever reason you might think likely, but which surely must have been an internal force, though there were no forces at the time.

Originally Posted by Cyberia

Originally Posted by KALSTER

I believe that is an important point that can't be stressed enough. It is a point of contention among many BBT naysayers. We simply don't know what the state of affairs were at t=0.

At t=0 for the universe, you have an impossible singularity come about in a fashion where god did it is as good as any other current explanation, which appeared in an "empty place". Since gravity did not exist then, it somehow had maintained form without it.

Then for some reason it suddenly decides to inflate then expand due to whatever reason you might think likely, but which surely must have been an internal force, though there were no forces at the time.

Please acknowledge that this singularity is not part of the Big Bang theory but a result of the maths involved that break down at this point in time. This only shows that the current theory does include t=0. It does not say that there actually was a singularity from which the universe emerged.

Originally Posted by MigL

Speedfreek you've shown commendable patience, but I think, now that a former member ( who had no patience for fools ) is gone, the crazys are trying to take over.

Not that I am adding much to the thread but I agree completely.

Very well Cyberia, I'll provide some theory by Alan Guth and Edward Witten, but I'll paraphrase.

In Newton's interpretation of gravity the force is dependant only on separation and mass.

Einstein re-defined gravity as a curvature of space/time dependant on mass, energy and pressure.
Now mass is easy to understand, and so is energy because it can be shown to be equivalent to mass, but actually increasing the temperature of a solid by about 10 degrees increases its mass by a miniscule amount ( don't want to do the calculation but probably about a trillionth of a gram ) and so the gravitational 'force' it exerts. Similarily pressure, a potential energy, increases the energy content of a mass, making it more 'massive' and generating a greater gravitatinal force. In effect compressing a spring, increases its mass and the gravitational force it exerts. Negative pressure would, by analogy, decreases potential energy, mass, and therefore gravitational force.

I believe it was Alan Guth, when he came up with inflation, who postulated the energy of the universe to have hung at a false vacuum state. Picture a U shaped curve with a bump in the middle, or a sombrero shape or the mold for a bundt cake. If the energy is hung on the central bump of the curve, the hat part of the sombrero if you will, before rolling down into the brim part, it can be shown using GR that this is negative pressure condition. If this negative pressure is large enough it will overcome the gravitational attraction of the universe and lead to inflation. This is the Higgs mechanism since it involves a spontaneous break in symmetry ( the top of the hat is perectly symmetric, but once it rolls down into the brim, symmetry is lost ), and the Higgs particle in this case is called an inflaton to distinguish it from the electroweak Higgs particle or the GUT particle.

Guth ( I believe, as its been a while since I read his stuff ) estimated that in the time it took for energy to roll down into the 'rim', about 10^-35 sec. the size of the universe increased by 10^30 to 10^100 in size ( depending on certain conditions ). This could still be happening on a much smaller scale, to account for the 'new cosmological constant', or the increase in expansion rate of the universe.

Witten, I believe, has speculated on a vacuum fluctuation in a space ( say right beside you) which 'borrows' energy for a short period of time and on the way to re-paying the loan, gets hung up of this false vauum energy level, leading to new universes being created wherever the negative pressure is sufficient to overcome gravity. These new universes are causally disconnected because of the large expansion rate, and its called chaotic inflationary theory.

Notice that Guth's inflationary theory doesn't deal with time t=0, but Witten's chaotic inflationary theory does, since its still happening and pre-supposes an endless regressin backwards ( although time for each universe still begins at time t=0 ). The other 'chaotic' univeses are however causaly disconnected and can therefore never be detected, so the theory can never be proven ( just like any other multiverse theory ).

And as for your signature...

You don't just memorise what's in books and regurgitate it. But you must have an understanding of what the books say in order to have a valid opinion. Otherwise YOU are just spouting gibberish.

Originally Posted by MigL

Very well Cyberia, I'll provide some theory by Alan Guth and Edward Witten, but I'll paraphrase.

In Newton's interpretation of gravity the force is dependant only on separation and mass.

Einstein re-defined gravity as a curvature of space/time dependant on mass, energy and pressure.
Now mass is easy to understand, and so is energy because it can be shown to be equivalent to mass, but actually increasing the temperature of a solid by about 10 degrees increases its mass by a miniscule amount ( don't want to do the calculation but probably about a trillionth of a gram ) and so the gravitational 'force' it exerts. Similarily pressure, a potential energy, increases the energy content of a mass, making it more 'massive' and generating a greater gravitatinal force. In effect compressing a spring, increases its mass and the gravitational force it exerts. Negative pressure would, by analogy, decreases potential energy, mass, and therefore gravitational force.

Sure you have e=mc2 so more energy must equal more mass, except that the "e" is the energy holding matter together and not matter itself. There is no comparison between the states of matter and energy as physics tells us and the belief that one can somehow change into the other is dogma. If you annihilate matter, what happens is you still have the fundamental particles left but without energy so they cannot be detected by detectors which rely on the energy of particles.

Adding energy to something merely increases the molecular motion so the force it can exert if confined or "weighed".

The only kind of negative pressure I know about is a vacuum and the BB tells us that there was literally nothing outside of the original singularity, so no vacuum as in no negative pressure.

I believe it was Alan Guth, when he came up with inflation, who postulated the energy of the universe to have hung at a false vacuum state. Picture a U shaped curve with a bump in the middle, or a sombrero shape or the mold for a bundt cake. If the energy is hung on the central bump of the curve, the hat part of the sombrero if you will, before rolling down into the brim part, it can be shown using GR that this is negative pressure condition. If this negative pressure is large enough it will overcome the gravitational attraction of the universe and lead to inflation. This is the Higgs mechanism since it involves a spontaneous break in symmetry ( the top of the hat is perectly symmetric, but once it rolls down into the brim, symmetry is lost ), and the Higgs particle in this case is called an inflaton to distinguish it from the electroweak Higgs particle or the GUT particle.

What would cause such a shape? There was no gravity or any other force originally. When gravity appeared it would have been helpless under inflation since that happened far faster than the speed of gravity (or light)., so no effect.

Guth ( I believe, as its been a while since I read his stuff ) estimated that in the time it took for energy to roll down into the 'rim', about 10^-35 sec. the size of the universe increased by 10^30 to 10^100 in size ( depending on certain conditions ). This could still be happening on a much smaller scale, to account for the 'new cosmological constant', or the increase in expansion rate of the universe.

Maths unfortunately in some cases just produces a better class of idiot as they build their castles on clouds. This is an IDEA and nothing more.

Witten, I believe, has speculated on a vacuum fluctuation in a space ( say right beside you) which 'borrows' energy for a short period of time and on the way to re-paying the loan, gets hung up of this false vauum energy level, leading to new universes being created wherever the negative pressure is sufficient to overcome gravity. These new universes are causally disconnected because of the large expansion rate, and its called chaotic inflationary theory.

Would you not have the possibility of endless universes encroaching on each other as they expanded if this were so?

Notice that Guth's inflationary theory doesn't deal with time t=0, but Witten's chaotic inflationary theory does, since its still happening and pre-supposes an endless regressin backwards ( although time for each universe still begins at time t=0 ). The other 'chaotic' univeses are however causaly disconnected and can therefore never be detected, so the theory can never be proven ( just like any other multiverse theory ).

Some now do think the universe may have came from literally nothing but this would have been more like a wildfire of particles appearing rather than something of ultimate density somehow forming.

Originally Posted by MigL

And as for your signature...

You don't just memorise what's in books and regurgitate it. But you must have an understanding of what the books say in order to have a valid opinion. Otherwise YOU are just spouting gibberish.

And I do understand and I have problems with their speculations.

You on the other hand have just regurgitated authors without any valid opinion on what they say other than the belief that they are right.

Originally Posted by Cyberia

Originally Posted by SpeedFreek

Actually, I don't think I showed enough patience, and I let myself down by getting too heated, for which I apologise to everyone including Stefan.

In any debate you have to accept that others will have different opinions (right or wrong).

Oh, I completely accept that other may have different opinions (right or wrong) about the subject at hand. It is when they are not even talking about the subject at hand, or fail to make clear how their input was relevant to the subject, that problems can occur.

Originally Posted by Cyberia

And I do understand and I have problems with their speculations.

You on the other hand have just regurgitated authors without any valid opinion on what they say other than the belief that they are right.

Unfortunately, one can only have a valid opinion on what they say, if one understands what they are saying, which requires at the very least an understanding of how General Relativity deals with space-time using an FLRW metric.

So, unless one is prepared to go through the rigours of learning General Relativity, one has to take the word of the experts in the subject.

Cyberia, are you arguing wth me or with Alan Guth and Edward Witten ??

You didn't even understand the ( very much ) simplified versions of their speculative theories that I posted, never mind the full versions, judging by your comments. Things like the difference between binding energy and mass/energy equivalence ( ever hear of pair creation and annihilation ??? ), or making the absurd leap from negative pressure to an outside to the universe, or even your ignorance of an energy well which can have such a shape for supercooled liquids or the magnetic domains in a simple magnet. Maybe you should do a little more reading and understand what's in those books before you post and demonstrate your ignorance.

While Guth's and Witten's theories cannot be proved yet, if ever, Tthey are at least mathematically self-consistant, while everything you state makes no mathematical sense at all.

Get a clue before you get an opinion.

Infinite extent of universe only means that however far you go, you will find matter bodies. Extent of our universe is limited by our ability to gain information from far. Extent of universe is identical in all directions from an observer. On a large scale, matter bodies are evenly distributed.

MigL. As intolerant as ever to those who do not parrot science books. I am arguing with your parrotings of those two people. I refer you again to my signature.

Here's some more points you can't answer but hand waving will make you if no one else, think you can:

"Mass energy equivalence is the concept that the mass of a body is a measure of it's energy content."

So we have protons which 2% mass and 98% energy. This explains it how?

Pair creation takes a lot of energy which is then lost in annihilation. What part of the word "energy" do you not understand?


If you have negative pressure from inside, it is going to struggle to stop expansion as in a vacuum stopping air from being released.

You then start blathering about energy as though you have something to say and are talking while you think of what it is.

If you base mathematical theories on conclusions and then base maths on those theories by simply moving figures about, though you will get correct answers, your conclusions may have an unsound cause so a completely wrong interpretation.

I always thought "theory" in a scientific context meant it had some firm basis in fact but you admit that they are no more than ideas which may never be proved.

Do you think your hand waving and parroting what you obviously don't understand fools anyone?

Why do you feel it necessary to insult what you do not understand?

Originally Posted by matterdoc

Infinite extent of universe only means that however far you go, you will find matter bodies. Extent of our universe is limited by our ability to gain information from far. Extent of universe is identical in all directions from an observer. On a large scale, matter bodies are evenly distributed.

If you take the big bang, while matter undergoing expansion would have expanded at a very slow rate; light, space and gravity would all have moved away from it's origin point at light speed so left the "matter universe" far behind.

However this applies for a 3D universe, but if you have expansion via a 4D hypersphere (which best suits expansion) instead then light is trapped into a "slowly" expanding universe, so it would ever criss-cross sections of the universe.

ie: In one second, light moves 186,282 miles, but in one second, a section of space one light second long is going to expand about the width of a hydrogen atom.

Originally Posted by SpeedFreek

Unfortunately, one can only have a valid opinion on what they say, if one understands what they are saying, which requires at the very least an understanding of how General Relativity deals with space-time using an FLRW metric.

So, unless one is prepared to go through the rigours of learning General Relativity, one has to take the word of the experts in the subject.

You either do not understand what the FLRW metric is about or you are just trying to dazzle us in the hope that no one will question you and so will think you have proved me wrong by uttering a buzz-phrase.

IF the BB had worked according to the FLRW metric, and it should have since it was expanding without bias into literally nothing, then we would have had a naturally homogenous and isotropic universe without any need for inflation.

However the universe is clearly neither, with a two billion solar mass black hole forming just 770 million years after the BB, with voids up to 3.5 billion light years across and with walls of hundreds of millions of galaxies.

Talking of tiny perturbations in the BB causing these is just mindless babble.

Originally Posted by Cyberia

"Mass energy equivalence is the concept that the mass of a body is a measure of it's energy content."

So we have protons which 2% mass and 98% energy.

Would you care to explain what this means? A proton is 100% mass and 100% energy, depending on how you see it. A proton and an anti-proton annihilate each other completely producing photons with the corresponding energy. What subsequently is produced from these photons is a totally different thing. Is your opinion different?

Originally Posted by Dishmaster

Originally Posted by Cyberia

"Mass energy equivalence is the concept that the mass of a body is a measure of it's energy content."

So we have protons which 2% mass and 98% energy.

Would you care to explain what this means? A proton is 100% mass and 100% energy, depending on how you see it. A proton and an anti-proton annihilate each other completely producing photons with the corresponding energy. What subsequently is produced from these photons is a totally different thing. Is your opinion different?

As I understand it, the quarks account for just 2% of the energy in a proton and the rest is.....?

An energy release produces photons. So?

Originally Posted by Cyberia

Originally Posted by SpeedFreek

Unfortunately, one can only have a valid opinion on what they say, if one understands what they are saying, which requires at the very least an understanding of how General Relativity deals with space-time using an FLRW metric.

So, unless one is prepared to go through the rigours of learning General Relativity, one has to take the word of the experts in the subject.

You either do not understand what the FLRW metric is about or you are just trying to dazzle us in the hope that no one will question you and so will think you have proved me wrong by uttering a buzz-phrase.

I do understand what the metric is about, and how it applies to the statements I quoted.

Originally Posted by Cyberia

IF the BB had worked according to the FLRW metric, and it should have since it was expanding without bias into literally nothing,{SNIP}

Excuse me? Expanding into "literally nothing"? It isn't expanding "into" anything, according to the model, as the expansion is intrinsic. Is this perhaps what you meant? Your comment could be taken either way - do expanding into "literally nothing" and not expanding into anything mean the same thing?

Originally Posted by Cyberia

then we would have had a naturally homogenous and isotropic universe without any need for inflation.

You could try explaining why.

Originally Posted by Cyberia

However the universe is clearly neither, with a two billion solar mass black hole forming just 770 million years after the BB, with voids up to 3.5 billion light years across and with walls of hundreds of millions of galaxies.

Talking of tiny perturbations in the BB causing these is just mindless babble.

Again, it would be nice if you explained why.

Oh, and I should add:

If you are merely ignoring what can be found in any science book, you are adding nothing to the debate. This is a science forum, after all.

I admit I may have been mistaken Cyberia, Chaotic Inflation may have been developed by Linde not Witten.

But as to my so called hand waving ( I think anything you don't understand, you call hand waving ), yes quark mass inside a nucleon like the proton may only be 2% of a proton's rest mass ( I won't bother to look up the rest mass of two up quarks and one down quark, I'll take your word for it ), but obviously you've never heard of binding energy. This is simply the energy that is converted from the mass difference of a Helium nucleus from two neutrons and two Hydrogen nuclei, and is the process which powers the Sun to give life on Earth ..., as an example.
For quarks the binding energy is even more formidable. I' m sure you've heard that free quarks cannot be produced because if you try to pull two of them apart, the energy expended in pulling will just produce two more bound quarks. In effect the binding energy is equivalent to the mass of two more quarks. So binding energy can account for quite a lot of mass.

Do you see where I'm going with this or don't you understand my 'hand waving' ???

Originally Posted by nimzo256

I have trouble in understanding how the universe can be infinite. It started off very small. It expanded.

Everything in the Universe now, must have been in it at the beginning. So I guess that it's infinite mass/energy was unchanged/ The volume at the beginning was infinite (actually a singularity, which doesn't mean a point, only that it was undetermined), after which it expanded.

[QUOTE=MigL;279987]I admit I may have been mistaken Cyberia, Chaotic Inflation may have been developed by Linde not Witten.[QUOTE]

It does not matter who developed it. I don't agree with it. Inflation is an explanation for a believed effect that we have no evidence for and I would need evidence before I can accept it.

But as to my so called hand waving ( I think anything you don't understand, you call hand waving ),

If I do not agree with something, it does not mean I do not understand it. That is a common assumption by any BB believer, that they cannot accept that there are any relevant possibilities other than their own.

yes quark mass inside a nucleon like the proton may only be 2% of a proton's rest mass ( I won't bother to look up the rest mass of two up quarks and one down quark, I'll take your word for it ), but obviously you've never heard of binding energy. This is simply the energy that is converted from the mass difference of a Helium nucleus from two neutrons and two Hydrogen nuclei, and is the process which powers the Sun to give life on Earth ..., as an example.

A prime example. 4 atoms of hydrogen produce one atom of helium by nuclear fusion with the byproduct being heat and light, so the sun. I got that as a kid at school.

A hydrogen nuclei. That would be a proton.

For quarks the binding energy is even more formidable. I' m sure you've heard that free quarks cannot be produced because if you try to pull two of them apart, the energy expended in pulling will just produce two more bound quarks. In effect the binding energy is equivalent to the mass of two more quarks. So binding energy can account for quite a lot of mass.

Quarks were only discovered fairly recently when high enough energies meant we split the proton (and neutron). Not exactly rocket science. The more energy necessary to split something, the more binding energy it has. Nearly as hard as 1+1.

Do you see where I'm going with this or don't you understand my 'hand waving' ???

You are making a big thing out of nothing. I call that "hand waving". You may have another name for it.