if the universe and space was created at the moment of the big bang where did the big bang happen At the instan before the event there was nowhere a?

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Unfortunately just because it's possible to frame a question does not mean that a meaningful answer must exist. For example: what is the colour of prayer? What is north of the North Pole?

What was before the big bang is probably a similar type of question.
 
Unfortunately just because it's possible to frame a question does not mean that a meaningful answer must exist. For example: what is the colour of prayer? What is north of the North Pole?

What was before the big bang is probably a similar type of question.
They seem to be meaningless questions to start with. Is it possible to ask a meaningful question which doesn't have a meaningful answer?

Anyway, the first law of thermodynamics, which says matter/energy can't be created or destroyed, implies that existence is eternal, so therefore there was something before the Big Bang! :)
 
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IG, Sorry if there is a misunderstanding. Cyclic does not mean repetitive. It is like (I am not saying is) starting with a black hole, being compressed - not totally to a singularity - and emerging through the nexus as a BB into another phase. No information survives passage through the nexus (as would happen if it were repetitive).

Cat :) :)
If no information passes through the Nexus does that mean your new bubble / pocket universe starts with either a blank slate or a random mess? If so, how do you get get all the order and structure you see in our universe today from either of those starting positions?

At what point in your theory does cause and effect breakdown and therefore the loss of information occur? :)

P.S. Your Nexus is much better than a singularity, though. :)
 
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Catastrophe

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D-J-F "
At what point in your theory does cause and effect breakdown and therefore the loss of information occur? :)"

Approaching BH = Nexus.I don't know.

"My" idea does not prohibit intermediate branching i.e., intermediate BHs leading to BBs but does not require them either. Networking.

"P.S. Your Nexus is much better than a singularity, though. :)"

Thank you.

Cat :)
 
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Is it possible to ask a meaningful question which doesn't have a meaningful answer?
Good question. No, because even, “Nobody knows” can be meaningful.

Anyway, the first law of thermodynamics, which says matter/energy can't be created or destroyed, implies that existence is eternal, so therefore there was something before the Big Bang! :)
But the thermo laws require initial conditions, as does all of physics. Some argue that many laws fail if applied to all the universe as a whole.
 
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Catastrophe

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if the universe and space was created at the moment of the big bang where did the big bang happen At the instan before the event there was nowhere a?

This question has really had a lot of answers, considering it does not really fit well with "reality".
If they were created at a time, where did it happen? If the BB were the start, how could there be a "where" already existing where it happened. We have had "before the BB", now we have "where before the BB".

Don't worry, I am not serious. If we can all mix up our definitions, even in the same sentence, then anything can mean anything, and we can all be happy.

Cat ;) ;) ;)
 
Good question. No, because even, “Nobody knows” can be meaningful.

But the thermo laws require initial conditions, as does all of physics. Some argue that many laws fail if applied to all the universe as a whole.
But the thermo laws require initial conditions,
I did not know that, all I can say is they must be wrong :)The first law seems pretty rock solid, if that required initial conditions it would contradict itself and it would require that something came from nothing, so I'll hold the first law is rock solid for now.

So, according to the first law existence is eternal. One of the interpretations of the second is that entropy always increases and according to the Big Bang Theory the universe will expand indefinitely and there will be a heat death. If entropy had always been increasing in an eternal universe there would already be nothing now, but because we are here proves there is a recycling mechanism in the universe.

So f the first law is true, the second law can't be, it needs fixing. Let me suggest Franks's amended second law of thermodynamics:):):) This states that there is an average value of entropy throughout The Infinite' (my word for the universe until Catastrophe told us otherwise) -

Franks's average entropy of The Infinite:):):).

In an infinite universe with an infinite number of Big Bangs at various stages in their cycle, a bigbang can only expand until it meets up with the rest of matter in the universe and therefore can only reach a certain level of entropy, ie the average entropy of the rest of the universe. It cannot expand forever, therefore no heat death.

Every time a big bang expands entropy increases. When gravity collapses matter to form a hot dense patch ready for the next big bang entropy decreases, ready to start a new fully feature-packed big bang.

This all belongs to what I call the 'Steady State of The Infinite' my name for my personal theory of the universe.

PS, I meant to say that in an eternal universe there are no initial conditions.
 
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David,
"In an infinite universe with an infinite number of Big Bangs at various stages in their cycle"
Without encouraging the word infinite ;) I have also posted an idea that BHs can collapse from 'branches' of 'The Universe' which branches can expand via BBs so producing a tree-like structure with branches which, however, can re-enter larger branches or even the tree trunk. All analogy, but another perspective on a cyclic model. There is little new under the Sun, so I expect someone has already had the same idea.

Cat :)
 
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"What was before the big bang is probably a similar type of question."

There are two views on this. The first, as you suspect, is that it is a non question. If, according to one point of view, the BB was the beginning of the Universe, then there is no time before t=0. The BB would be seen as a combination of space and time, or spacetime, and before this began would be seen as meaningless.

There is another, more difficult point of view, that the Universe did not begin with the BB, but that the BB was actually a nexus between one phase of the Universe and another. Instead of a singularity which is supposed to be a point of infinite density and infinite temperature, there would be a narrow channel through which energy rushed from a black hole in the previous phase to the new phase, which experienced it as "the" BB. This is a comparatively unorthodox point of view but has some support.

There is detailed information available in threads found under Forum Feedback titled "Agreed terms help sensible discussion" further titled Universe, Big Bang and Singularity. These provide extracts from various sources including a variety of points of view. I hope you find these helpful. If you wish, you can put further questions there, or, if you prefer, bring your questions back here.

Best wushes,

Cat :)
 
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So, according to the first law existence is eternal. One of the interpretations of the second is that entropy always increases and according to the Big Bang Theory the universe will expand indefinitely and there will be a heat death.
Since we want to be specific about what the BBT says, the BBT doesn't predict the actual shape (e.g. "Flat") of the Universe, so it can make no prediction on its future. I think most assumed the expansion was slowing and might eventually collapse, hence the cyclical universe ideas emerged. The discovery of an accelerating universe was a big surprise, in 1995, IIRC.

If entropy had always been increasing in an eternal universe there would already be nothing now, but because we are here proves there is a recycling mechanism in the universe.
The Steady State theory predicted something similar, especially the emergence of hydrogen in space, somehow, to replenish stars to continue fueling the universe.

Stars can "burn" for over a trillion years -- not the big ones -- and new stars are still forming, but not as prolific as in the past. Until they all fizzle out, there will still be an increase in entropy. But with accelerated expansion, if it continues, we won't have "heat death" but a cold one.

Franks's average entropy of The Infinite:):):).
That's an interesting idea... on average. ;) Perhaps there's a given rate of entropy production that may apply.

Every time a big bang expands entropy increases.
I'm unclear if this idea is correct. With expansion comes a universe that becomes a cooler heat sink, which increases the delta T, which is a form of negative entropy, but I'm very rusty with this so I could be missing something.

When gravity collapses matter to form a hot dense patch ready for the next big bang entropy decreases, ready to start a new fully feature-packed big bang.
How does collapsing produce negative entropy?

PS, I meant to say that in an eternal universe there are no initial conditions.
That goes to the heart of the problem in physics -- no initial conditions, no physics. This is another reason why it helps to use today's set as the "initial conditions" and work backwards till the "wheels fly off the wagon". :)
 

Catastrophe

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Re: entropy.
Expansion goes hand in hand with increasing entropy. Consider salt (NaCl) crystals dissolved in water. As they dissolve they have greater freedom of movement, and distribute evenly (statistically) into the increasing volume of water. Correspondingly, with expansion of the Universe, all matter has greater freedom of movement ('choice') - hence increasing entropy. If the situation is reversed, freedom is reduced and entropy reduces with it. That, imho, says reduction in concentration ('options, choices') makes reduction in entropy 'the way' of the Universe. That's just my take.

Now, something VERY important. We have the word Universe defined as 'absolutely all there is', 'the totality'. Then our experience widened. We started thinking of 'objects' with properties which we associated with our 'Universe', so we called the 'universe' as well. This is wrong! We need two different words to describe these two different concepts. At the moment we use 'U' for the total Universe, and 'u' for these new universes.
This is not working. It is completely confusing, especially to those who do not even know that there is a distinction. Who is going to sort this out? My guess is no one. We just have to try to spread the idea ourselves.

Cat :)
 
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Since we want to be specific about what the BBT says, the BBT doesn't predict the actual shape (e.g. "Flat") of the Universe, so it can make no prediction on its future. I think most assumed the expansion was slowing and might eventually collapse, hence the cyclical universe ideas emerged. The discovery of an accelerating universe was a big surprise, in 1995, IIRC.

The Steady State theory predicted something similar, especially the emergence of hydrogen in space, somehow, to replenish stars to continue fueling the universe.

Stars can "burn" for over a trillion years -- not the big ones -- and new stars are still forming, but not as prolific as in the past. Until they all fizzle out, there will still be an increase in entropy. But with accelerated expansion, if it continues, we won't have "heat death" but a cold one.


That's an interesting idea... on average. ;) Perhaps there's a given rate of entropy production that may apply.

I'm unclear if this idea is correct. With expansion comes a universe that becomes a cooler heat sink, which increases the delta T, which is a form of negative entropy, but I'm very rusty with this so I could be missing something.

How does collapsing produce negative entropy?

That goes to the heart of the problem in physics -- no initial conditions, no physics. This is another reason why it helps to use today's set as the "initial conditions" and work backwards till the "wheels fly off the wagon". :)
The discovery of an accelerating universe was a big surprise, in 1995, IIRC.
I Guess That's Why Why everyone thinks there's going to be a heat death of the universe. I think it is still is the majority opinion that this is what's going to happen, maybe you could ask Dr Joe.
The Steady State theory predicted something similar, especially the emergence of hydrogen in space, somehow, to replenish stars to continue fueling the universe.
A little similar, except my theory replenishes big bangs rather than stars. Mine is infinite, but I think the Steady state Theory was infinite as well, I'm not sure.
Stars can "burn" for over a trillion years -- not the big ones -- and new stars are still forming, but not as prolific as in the past. Until they all fizzle out, there will still be an increase in entropy. But with accelerated expansion, if it continues, we won't have "heat death" but a cold one.
OK, a cold death then, were the universe keeps expanding until there's no heat left in it. This absurd idea requires that there is only one big bang in existence and that there is an infinite void around it into which it can keep expanding indefinitely.

Having an infinite universe with infinite number of big bangs in it solves this problem, because, as mentioned earlier the expansion of one big bang will come to an end when it meets the rest on the matter and other big bang in the universe. So no cold death, more like a warm ending for that particular big bang :) the entropy in that particular big bang will then have become Frank's average entropy of The Infinite.

One main difference between my theory and the Big Bang Theory is that in The Big Bang Theory, it is an open system, in other words the universe can keep expanding and heat and energy and matter can keep dispersing indefinitely. Whereas, in my 'The Infinite'' which is full of stuff, and other big bangs, there is no nowhere for things to keep expanding, it can be regarded as a closed system, so all the matter, energy, entropy, gravitational field and information per cubic Lightyear is constant on average throughout 'The Infinite'.

So now, once again being arrogant:) I have introduced

Frank's average matter/energy density of The Infinite

And

Franks's average gravitational field of The Infinite

It's possible that that particular expanding big bang might overshoot when it meets up with the rest of the matter in The Infinite and so temporarily, it's entropy will increase above the average entropy value. Gravity should contract it so it comes back to the average entropy value.
That's an interesting idea... on average. ;) Perhaps there's a given rate of entropy production that may apply.
No, there can't be an indefinite increase of entropy in an infinite eternal universe. It behaves like a closed system. the amount of entropy stays the same on average throughout. All the parameters of an infinite eternal universe must on average remain the same, hence my name - Steady State of the Infinite

Once again if entropy were allowed to keep increasing in an Infinite eternal universe there would be nothing by now.
I'm unclear if this idea is correct. With expansion comes a universe that becomes a cooler heat sink, which increases the delta T, which is a form of negative entropy, but I'm very rusty with this so I could be missing something.
I don't think there's such thing as negative entropy, just high and low. I think at the start of the big bang it was 0 and it is now increasing towards 1. I think 1 is the maximum value but I'm not sure what scale they use. The current thinking is that the contents of the Big Bang are expanding indefinitely and therefore the entropy is increasing towards complete disorder and heat death or cold death as you put it.

We are in a big bang and entropy is increasing at the moment, but scientists are too short-sighted to see that there must be a mechanism to end expansion sometime so they assume it will carry on forever expanding. Absurd in my opinion
How does collapsing produce negative entropy?
Simple, gravitational collapse of a low entropy gas cloud - to solar system - to you and me, low entropy and a highly ordered world.

It's not negative entropy it goes to, its lower entropy, or a negative change if you like.

When gravity collapses something entropy decreases and when something expands entropy increases. When when matter collapses back into a hot dense patch ready for a new big bang its entropy will have gone back to zero.
That goes to the heart of the problem in physics -- no initial conditions, no physics. This is another reason why it helps to use today's set as the "initial conditions" and work backwards till the "wheels fly off the wagon". :)
but we are in an eternal universe and there are no initial conditions and yet we still have some physics.

The big bang was not the start of anything it was a point of maximum compression it was part of a continuous recycling process. There isn't a point in it where you can say physics started or stoped anywhere, if there's physics now then there is always been some physics. The big bang wasn't a disconnection from the rest of reality it was a continuation of it.:)
 
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A little similar, except my theory replenishes big bangs rather than stars. Mine is infinite, but I think the Steady state Theory was infinite as well, I'm not sure.
Yes, because the standard view of the cosmos prior to BBT was the Static model, namely the universe was ageless and infinite, likely. But this introduces that element of bias that greatly tripped Einstein, else he would have introduced the BBT, not Lemaitre. He even got a push from Friedman to think seriously about it, but he muffed it.

OK, a cold death then, were the universe keeps expanding until there's no heat left in it. This absurd idea requires that there is only one big bang in existence and that there is an infinite void around it into which it can keep expanding indefinitely.
Yep, just not absurd and there is no science for what is outside the Universe, just pseudoscience. :)

Having an infinite universe with infinite number of big bangs in it solves this problem, because, as mentioned earlier the expansion of one big bang will come to an end when it meets the rest on the matter and other big bang in the universe. So no cold death, more like a warm ending for that particular big bang :) the entropy in that particular big bang will then have become Frank's average entropy of The Infinite.
Yeah, well it's funny how infinite stuff makes everything look average. Another reason I'm not fond of infinities. ;)

One main difference between my theory and the Big Bang Theory is that in The Big Bang Theory, it is an open system, in other words the universe can keep expanding and heat and energy and matter can keep dispersing indefinitely. Whereas, in my 'The Infinite'' which is full of stuff, and other big bangs, there is no nowhere for things to keep expanding, it can be regarded as a closed system, so all the matter, energy, entropy, gravitational field and information per cubic Lightyear is constant on average throughout 'The Infinite'.
Ok, but remember that a scientific theory isn't the same as suppositional ideas.

No, there can't be an indefinite increase of entropy in an infinite eternal universe. It behaves like a closed system. the amount of entropy stays the same on average throughout. All the parameters of an infinite eternal universe must on average remain the same, hence my name - Steady State of the Infinite
But in a steady closed system, increasing entropy must be compensated with decreasing entropy. So where will that come from? "Heat won't flow from a cooler to a hotter. You can try if you like, but you far better noter!"

I don't think there's such thing as negative entropy, just high and low.
Entropy changes and is formulated by heat transfer -- energy per unit time. So entropy can either increase or decrease. A refrigerator is a common example of a closed system with negative entropy. Those thermo equations will tell you how fast things will cool inside. But the bigger picture shows it uses a heat sink (the Universe) to accomplish this cooling, hence the net energy result produces an overall entropy increase.

It's not negative entropy it goes to, its lower entropy, or a negative change if you like.
Yes, the overall entropy of the Universe is the ultimate question. Either it goes up or goes down. Only local events can present a negative entropy result, meaning there is negative heat flow along an isotherm.

When gravity collapses something entropy decreases...
When does that work? If an asteroid, for example, converts its gravitational energy to melting Earth upon impact, that's an entropy increase we need to avoid.
 
Re: entropy.
Expansion goes hand in hand with increasing entropy. Consider salt (NaCl) crystals dissolved in water. As they dissolve they have greater freedom of movement, and distribute evenly (statistically) into the increasing volume of water. Correspondingly, with expansion of the Universe, all matter has greater freedom of movement ('choice') - hence increasing entropy. If the situation is reversed, freedom is reduced and entropy reduces with it. That, imho, says reduction in concentration ('options, choices') makes reduction in entropy 'the way' of the Universe. That's just my take.

Now, something VERY important. We have the word Universe defined as 'absolutely all there is', 'the totality'. Then our experience widened. We started thinking of 'objects' with properties which we associated with our 'Universe', so we called the 'universe' as well. This is wrong! We need two different words to describe these two different concepts. At the moment we use 'U' for the total Universe, and 'u' for these new universes.
This is not working. It is completely confusing, especially to those who do not even know that there is a distinction. Who is going to sort this out? My guess is no one. We just have to try to spread the idea ourselves.

Cat :)
Re: entropy.
Expansion goes hand in hand with increasing entropy. Consider salt (NaCl) crystals dissolved in water. As they dissolve they have greater freedom of movement, and distribute evenly (statistically) into the increasing volume of water. Correspondingly, with expansion of the Universe, all matter has greater freedom of movement ('choice') - hence increasing entropy. If the situation is reversed, freedom is reduced and entropy reduces with it. That, imho, says reduction in concentration ('options, choices') makes reduction in entropy 'the way' of the Universe. That's just my take.
I totally agree with that. I was writing the reply to helio when your post came.in, I didn't bother to read it as I carried on writing my post. it took me 2-hours fiddling about on my smartphone. So, having recovered from that I can now reply to this post.

Don't worry I'm still on the case of the Universe. I've already written a draught for it, I'll post it soon. It should sought absolutely everything out :) :):)
 
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Yes, because the standard view of the cosmos prior to BBT was the Static model, namely the universe was ageless and infinite, likely. But this introduces that element of bias that greatly tripped Einstein, else he would have introduced the BBT, not Lemaitre. He even got a push from Friedman to think seriously about it, but he muffed it.

Yep, just not absurd and there is no science for what is outside the Universe, just pseudoscience. :)

Yeah, well it's funny how infinite stuff makes everything look average. Another reason I'm not fond of infinities. ;)

Ok, but remember that a scientific theory isn't the same as suppositional ideas.

But in a steady closed system, increasing entropy must be compensated with decreasing entropy. So where will that come from? "Heat won't flow from a cooler to a hotter. You can try if you like, but you far better noter!"

Entropy changes and is formulated by heat transfer -- energy per unit time. So entropy can either increase or decrease. A refrigerator is a common example of a closed system with negative entropy. Those thermo equations will tell you how fast things will cool inside. But the bigger picture shows it uses a heat sink (the Universe) to accomplish this cooling, hence the net energy result produces an overall entropy increase.

Yes, the overall entropy of the Universe is the ultimate question. Either it goes up or goes down. Only local events can present a negative entropy result, meaning there is negative heat flow along an isotherm.

When does that work? If an asteroid, for example, converts its gravitational energy to melting Earth upon impact, that's an entropy increase we need to avoid.
I made a mistake in my above post, I too fell victim to the misconception that the Big Bang created the universe. How many times have you seen in the Press where scientists say the universe started with the big bang or the big bang was the beginning of the universe. We have been brainwashed into thinking the Big Bang is the universe.

If you use the proper definition of universe that now reads as the big bang was the creation of everything that exists. This is completely ridiculous and there is absolutely no reason to assume this, especially since that everything that exist is unknowable. I don't know who said it the first place.

I think it's safe to assume the big bang is not the Universe.

So if I could now ask you you to substitute contents of Big Bang for every where you saw me use the word universe with small u. For example when I said universe expanding that should read contents of Big Bang expanding I hope that makes more sense. The Universe cannot expand as has already been discussed many times as there is nowhere for it to expand it is already everything that exists.
Yep, just not absurd and there is no science for what is outside the Universe, just pseudoscience. :)
I will stand by saying the indefinite expansion of the universe (common popular meaning, ie contents of the Big Bang) is absurd.

The first law means existence is eternal. If nature only allowed a one-way expansion without any recycling there would be nothing now. No science is needed for what is beyond the Big Bang because if anyone is claiming it is going to expand indefinitely that automatically implies there is an infinite amount of empty space for it to do so. If you don't know what is beyond the big bang then you can't claim it is going to expand indefinitely!!!
Yeah, well it's funny how infinite stuff makes everything look average. Another reason I'm not fond of infinities. ;)
Seriously, it does solve a lot of problems everything does have to be average. If the laws of physics are the same throughout The Infinite (Universe) then whatever gives rise to stuff in one location must apply to any other location, so it will all be similar, there can't be a reason for something to be drastically different one side of the Universe than the other. There is a common connection throughout The Infinite, both with the laws of physics and probably space is full of all the same quantum field throughout as well. Any imbalances would even out after an infinite amount time. I know that's a crude way of putting it, in other words and imbalance can't exist.

Also scientists love symmetry, the infinite is symmetrical on average in all directions and from all places it is also symmetric from past to future.

If you don't like infinities, then a finite Universe brings all those problems of what is beyond it and what's it expanding into excetera.
Ok, but remember that a scientific theory isn't the same as suppositional ideas.
Ok, the universe (contents of Big Bang) is expanding, that's science, but there is no evidence to suggest that it will expand forever i.e. there is no evidence of an infinite void for it to do so, so that part of the theory is suppositional, so I am entitled to say that it won't expand forever, equally without any evidence, the only difference is mine is based on logic and is more sensible. :)

I'm not denying the Big Bang I am including it in my theory. I have given it a before a beyond an after and a place to reside, hopefully giving people something to think about instead of being completely left in the dark.
But in a steady closed system, increasing entropy must be compensated with decreasing entropy. So where will that come from? "Heat won't flow from a cooler to a hotter. You can try if you like, but you far better noter!"
Yes it will, in nature, you can get from cold to hot, when a cold gas cloud collapses into a hot star.

Yes the star formation is a local decrease of entropy and overall entropy will still increase in the whole contents of the Big Bang. The Big Bang Theory is an open system so the entropy will keep increasing. However, don't forget in my theory a big bang will reside in The Infinite, so a big bang is now a local event so so it can have a low entropy when it first formed, just as the star did, due to the gravitational collapse of the matter that went to form the first initial hot dense patch for that big bang.

And because The Infinite behaves as a closed system no heat is permanently dispersed there is nowhere for it to go. Entropy will still stabilize at Frank's average entropy of The Infinite:)
Entropy changes and is formulated by heat transfer -- energy per unit time. So entropy can either increase or decrease. A refrigerator is a common example of a closed system with negative entropy. Those thermo equations will tell you how fast things will cool inside. But the bigger picture shows it uses a heat sink (the Universe) to accomplish this cooling, hence the net energy result produces an overall entropy increase.
There can no overall heat transfer in an infinite Universe, so entropy will stay at an average value, it will fluctuate up and down but always come back to an average value.

Yes heatwise your man-made fridge example is good example similar to the star example, except the star is a natural phenomenon so hopefully more relevant.

In a one-off big bang universe which is expanding the heat from the fridge is permanently lost but where a big bang resides in The Infinite there is no overall heat lost, there is nowhere for it to go. It's a different situation altogether.

Sorry to nitpick, but once again I think you'll find there's no such thing as negative entropy there's only positive or negative entropy change. The most highly ordered state of something is assigned an entropy of 0 and it can only increase positively from there or reverse from an already positive value as with your fridge example.
When does that work? If an asteroid, for example, converts its gravitational energy to melting Earth upon impact, that's an entropy increase we need to avoid.
I gave you an example, star system formation. It must work or we wouldn't be here.:)
 
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"Sorry to nitpick, but once again I think you'll find there's no such thing as negative entropy "

In an expanding Universe.

Would you find negative entropy in a contracting Universe?

Granted that we have no experience of that.

Cat :)
 
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The Universe cannot expand as has already been discussed many times as there is nowhere for it to expand it is already everything that exists.
All the evidence points to an expanding Universe. There is no BBT without expansion.

I will stand by saying the indefinite expansion of the universe (common popular meaning, ie contents of the Big Bang) is absurd.
You're entitled to this opinion especially since it isn't a question science can answer.

The first law means existence is eternal.
It is based upon what we see after things were created, so only from some point on or after the beginning (t=0) does this law, and ALL the others, take effect. The creation included the stuff needed to make it all work, essentially, in a near-perfect (ie finely-tuned) way.

... if anyone is claiming it is going to expand indefinitely that automatically implies there is an infinite amount of empty space for it to do so.
"Empty space" outside of space demonstrates how confusing metaphysics can get.

If you don't know what is beyond the big bang then you can't claim it is going to expand indefinitely!!!
Agreed. I think most are just referring to a likely scenario over, say, the next 20 billion years. The acceleration of spacetime argues this point. But we don't know what DE is, so how do we know it, or something related, won't do something funky in, say, 50 billion years?

... there can't be a reason for something to be drastically different one side of the Universe than the other.
Right, the BBT argues for an isotropic and homogenous universe (cosmological principle).

Also scientists love symmetry, the infinite is symmetrical on average in all directions and from all places it is also symmetric from past to future.
How do we test for symmetry where the ends can't be found to flip it for that test?

Ok, the universe (contents of Big Bang) is expanding, that's science, but there is no evidence to suggest that it will expand forever i.e. there is no evidence of an infinite void for it to do so, so that part of the theory is suppositional,
Agreed.

so I am entitled to say that it won't expand forever, equally without any evidence, the only difference is mine is based on logic and is more sensible. :)
We have no testable premises to make one view more better than annuder. ;)

Yes heatwise your man-made fridge example is good example similar to the star example, except the star is a natural phenomenon so hopefully more relevant.
The analogy is to emphasize that even when entropy decreases (in one spot) the overall entropy for the Universe increases. Stars are losing their available energy every second, thus entropy is increasing.

In a one-off big bang universe which is expanding the heat from the fridge is permanently lost ...
The lowest state of entropy was during the beginning. Hydrogen gives us the best known energy production so its creation required the lowest entropy state, thus at the beginning. Fusion ever since has increased entropy.

Sorry to nitpick, but once again I think you'll find there's no such thing as negative entropy there's only positive or negative entropy change.
Entropy is defined as heat flow along an isotherm, so yes, it is a difference in two states. Some just use the "negative entropy" as a way to state a direction a process is going between two states.
 
"Sorry to nitpick, but once again I think you'll find there's no such thing as negative entropy "

In an expanding Universe.

Would you find negative entropy in a contracting Universe?

Granted that we have no experience of that.

Cat :)
No you would not find negative entropy in a contracting universe. There is no such thing as negative entropy. The lowest entropy can get is 0 and this represents the most highly ordered arrangement possible. You cannot go below 0 entropy to negative entropy.

What you find in a contracting universe is negative entropy change. It still always remains a positive value above 0, but it is going in a negative direction to a lower positive value.
 
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Catastrophe

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David, there are two (other) ways of looking at negative entropy. I would start by saying that if entropy is an increase in disorder, then, in a contracting Universe (granted this is supposition) the particles get closer and closer together and are forced into some sort of increasing order. Am I wrong in suggesting this would be negative entropy (not localised decrease in entropy, but overall increase in order?

The clincher for me is, in this model (supposition) there is a cyclic process so order must return to maximum (closest proximity) and entropy to minimum. After all, with the BBM do we start with minimum entropy followed by increasing entropy, and do we not return to this state (or a close approximation)?

This either supports or destroys the cyclic model(s).

Cat :)
 
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Catastrophe

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IG, Do you remember the flatlander analogy?

(n + 1) simply means a higher dimension than is available to (n). I am suggesting (not by way of proof, but as supposition) that one is asking an impossible question, for the (n) dimensional being to understand..

A flatlander cannot understand expansion of 'his' universe, beyond the surface of the sphere. The (n + 1) being, in this case, us, can perceive an additional meaning or cause of expansion, which is increasing radius.

In this model, there is no suggestion of more than one Universe. What differs is the perception of that Universe. The universe (as perceived by the flatlander) is not a different Universe, it is a different slice, a different perception of the Universe. Obviously there are as many universes (as perceived by a flatlander) as there are spheres with surfaces. There can be no communication between these universes except and unless any of these spheres touch. What happens then, I am not sure.

As far as we are concerned, and this is entirely supposition based on analogy, it may be (and probably is) the case that what we perceive as expansion of the Universe is just expansion of one perceived universe, viz limited by our perceptions as governed by our senses (and artificial extensions of our senses such as telescopes).
On this basis I would agree (with reservations) that there could/might be any number of perceived universes, but they would be slices of the Universe as defined by our perceptions.

Cat :)
 
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