Where Does Space End? It Must End Somewhere!

[David Levy]

The extra heat is distributed over a greater volume.

 

Please study the following entry thermodynamic formula.

 

[latex]pV=nRt[/latex]

 

p=pressure

V=volume

N number of moles (particles)

t =temperature.

R is the ideal, or universal, gas constant, equal to the product of the Boltzmann constant and the Avogadro constant.

 

Until you understand This equation there is no point in explaining how it works for an adiabatic fluid.

Here is a half decent coverage.

 

http://www.google.ca/url?q=http://authors.library.caltech.edu/25050/4/Chapter_03.pdf&sa=U&ved=0ahUKEwjJu-iE44DMAhUQ72MKHQB4D3AQFggRMAA&usg=AFQjCNGBdw9SjCUJw0FFlrOYC-hyANKbhg

 

As the Volume increases BOTH the temperature and pressure drops

The universe is modelled as an adiabatic and isentropic fluid.

 

Meaning there is no net outflow of energy. The isentropic term refers to adiabatic and reversible.

 

With regards to that formula:

 

We take it for granted that there is no change in - N number of moles (particles)

 

In this case, it is clear that:

 

As the Volume increases BOTH the temperature and pressure drops

 

However, if we assume that the N number of moles (particles) is not constant.

 

Then, theoretically, we can claim that:

 

As the Volume increases, the number of moles (particles) increases.

 

If it is equally balanced, then there is no need to set any change in BOTH the temperature and pressure.

 

If this is correct, it could supports the Idea that new mass is created while the universe expands to the infinity without any negative impact on temp and pressure.

 

[Strange]

If this is correct, it could supports the Idea that new mass is created while the universe expands to the infinity without any negative impact on temp and pressure.

 

This sounds like a version of Hoyle's quasi-steady state theory.

 

It doesn't fit the evidence (of an early hot universe). And there is no evidence that mass is, or can be, created at the required rate.

[David Levy]

 

This sounds like a version of Hoyle's quasi-steady state theory.

 

It doesn't fit the evidence (of an early hot universe). And there is no evidence that mass is, or can be, created at the required rate.

 

We can verify it quite easily by the CMB level.

 

If there is no change in the CMB level (in the next 1 million/billion year), than this is correct.

 

If there is a change in the CMB in the future, then it is clear that As the Volume increases BOTH the temperature and pressure drops.

 

[Strange]

If there is no change in the CMB level (in the next 1 million/billion year), than this is correct.

 

Whether it changes or not is not the point. Its existence is evidence for the cooling universe and against the steady state model.

 

But you have had this explained to you very many times. Please stop pretending that you don't know this.

[David Levy]

Question:

Based on our current understanding about the Universe -

Do we expect to see any change in the CMB level in the Future? (1 Million, One Billion or even one trillion years from now)

In the same token, what was the expected CMB level one billion or 10 Billions years ago?

Edited April 9, 2016 by David Levy

[Strange]

Question:

Based on our current understanding about the Universe -

Do we expect to see any change in the CMB level in the Future? (1 Million, One Billion or even one trillion years from now)

In the same token, what was the expected CMB level one billion or 10 Billions years ago?

 

You have had an entire thread about this. Have you forgotten already? The temperature of the universe (as reflected by the CMB) decreases (roughly) linearly with time.

[Airbrush]

However infinity can increase in size

There is no limit to infinity.

 

You know more about this subject than I do. Most of what I know about cosmology just comes from documentaries on TV.

 

So I'd like to hear how something infinite in size can increase in size.

[Delta1212]

 

You know more about this subject than I do. Most of what I know about cosmology just comes from documentaries on TV.

 

So I'd like to hear how something infinite in size can increase in size.

It was already linked in the thread, but I'll link it again since you may have missed it:

 

https://en.m.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel

[David Levy]

 

The temperature of the universe (as reflected by the CMB) decreases (roughly) linearly with time.

Thanks

 

So the CMB level should decrease linearly with time.

 

Technically, based on our sensitive and advanced detectors, I assume that we should discover minor decrease even in a range of our life time.

This should proof that our current theories (BBT) are fully correct.

However, if it will be discovered that even after quite significant time, there is no change in that CMB level.

 

Don't you think that there is a meaning for that?

 

I'm not asking about steady state.

 

I just wonder if it is feasible that the Universe expands to the infinity without any change with its pressure and temp.

[Strange]

Technically, based on our sensitive and advanced detectors, I assume that we should discover minor decrease even in a range of our life time.

 

As you have been told before, any such change will not be measurable in our lifetime.

 

This should proof that our current theories (BBT) are fully correct.

 

Science never proves anything fully correct. (As I am sure you have been told before.)

 

I just wonder if it is feasible that the Universe expands to the infinity without any change with its pressure and temp.

 

You can wonder all sorts of things. But without evidence it is just science fiction.

[Mordred]

Just to add some details. When you study particle physics in great detail. One comes to understand that particles are "Excitations in a field".

 

So in point of detail from the classical formula I posted above, when you get into the quantum aspects, you start to learn that the number density of bosons and fermions can be calculated in any blackbody temperature.

 

If you ever get into the Advanced formulas, the two main formulas is the Bose-Einstein statistics and the Fermi-Dirac statistics.

These collectively can be combined into the Maxwell-Boltzmann statistics which is more practical in a blackbody where all known particles have dropped out of thermal equilibrium.

 

Armed with the above and using particle physics one can then start calculating the % of elements that we can easily detect.

 

For example, hydrogen, helium, lithium etc.

 

These elements we can identify and measure with spectrography.

 

Through These methods and numerous others we can TEST whether or not the number of particles are roughly the same.

 

A reduction through nucleosynthesis and spectrography can be detectable.

Another key evidence that there is no net outflow of energy, is that nucleosynthesis was able to predict the % of hydrogen, helium, lithium etc to a rather high degree of accuracy based upon the above prior to being able to measure those percentages.

( not too many people fully understand the significance of predicting those percentages as accurately as the LCDM model did)

 

 

Even more incredible, is that the only method to average the number density of particles prior to being able to measure the CMB was by "Counting Stars" study a region and average that mass density to the Volume of the Universe.

 

Yet even this seemingly inaccurate method allowed us to predict the correct values.

[Strange]

Just found this excellent summary of the CMB: http://www.cv.nrao.edu/course/astr534/CMB.html

Edited April 9, 2016 by Strange

[Mordred]

Not a bad link, it covers all the basic aspects. Without going too in-depth

Edited April 9, 2016 by Mordred

[Airbrush]

It was already linked in the thread, but I'll link it again since you may have missed it:

 

https://en.m.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel

 

Very interesting about the Grand Hotel Paradox. Thanks for posting that. Too bad it doesn't mention a universe that has an infinite diameter and how it can grow any larger. Can anyone think of another model comparable to the Grand Hotel Paradox to explain how the big bang could produce a universe that has an infinite diameter and yet keeps growing? That is beyond my ability to grasp using geometry of 3 dimensions: x, y, and z axes. Are you saying infinity is a quantity that you can add numbers to? That seems like cheating to me, infinity is already infinite. Adding a finite number to infinity is comparable to dividing a real number by zero.

 

"...Choosing a Cartesian coordinate system for a three-dimensional space means choosing an ordered triplet of lines (axes) that are pair-wise perpendicular, have a single unit of length for all three axes and have an orientation for each axis. As in the two-dimensional case, each axis becomes a number line."

 

https://en.wikipedia.org/wiki/Axis_(mathematics)

Edited April 10, 2016 by Airbrush

[David Levy]

You tend to keep mixing The (Entire) Universe with The Observable Universe.

Try this for visualisation:

Currently our Observable Universe seems to be this big:

--> O

But from evidence (see previous in this thread) it's been expanding, and previously was this big:

--> .

(i.e. the Observable Universe went from "." to "O").

However, we don't expect that The Observable Universe (O) is The (Entire) Universe. From the evidence (see previous in this thread) it's probably many times bigger:

--> OOOOOOOOOO

Which would mean it was probably once like:--> ..........

 

Thanks for the explanation

However, I assume that there is a small problem with the CMB blackbody radiation.

http://www.cv.nrao.edu/course/astr534/CMB.html

 

"How does the blackbody CMB evolve as the universe expands? The universe is spatially homogenous and isotropic, so the properties of the CMB can be calculated by considering what happens to blackbody radiation in a small cube whose side length a(t)slowly grows with time t since the big bang. "Small" here means only much smaller than the Hubble distancecH0300105 km s−173 km s−1 Mpc−141103 Mpc so that relativistic effects can be ignored."

 

If I understand it correctly, the Universe should be quite small in order to create that kind of blackbody radiation.

 

But, The Universe might actually be infinite:

--> --- OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ---

Which expanded from an infinite:

--> --- .................................................. ---

... and how an infinite dense thing can expand to an infinite less-dense thing, see Hilbert Hotel (previous in this thread).

 

However, if the Universe expands from Infinite, than it can't be considered as "small".

In this case, how could it have a CMB blackbody radiation?

Edited April 10, 2016 by David Levy

[Strange]

Very interesting about the Grand Hotel Paradox. Thanks for posting that. Too bad it doesn't mention a universe that has an infinite diameter and how it can grow any larger. Can anyone think of another model comparable to the Grand Hotel Paradox to explain how the big bang could produce a universe that has an infinite diameter and yet keeps growing?

 

Imagine you are looking at an infinitely long ruler (like the number line). With markings every cm (or inch, if you are stuck in the 19th century). Now, imagine the ruler stretches so all the marking are twice as far apart. The ruler is still infinitely long, but it has scaled by a factor of 2. (Or the "density" of the marks has fallen by half).

 

Does that help?

 

If I understand it correctly, the Universe should be quite small in order to create that kind of blackbody radiation.

 

We can, as always, safely assume that you don't understand.

 

Nowhere does it say that the universe should be small to create black body radiation. All it says is that it is easier to analyse what happens by just looking at one small volume. All the rest of the universe is made up of similar volumes and so whatever we deduce for that one volume applies to the rest of the universe.

 

However, if the Universe expands from Infinite, than it can't be considered as "small".

 

Indeed. However it was denser - and therefore hotter. (Do you begin to see a pattern here).

 

In this case, how could it have a CMB blackbody radiation?

 

Because it was initially too hot and dense for light to travel any distance. Then it cooled enough for the electrons and protons to form atoms of hydrogen, at which point the universe became transparent.

[Airbrush]

 

Imagine you are looking at an infinitely long ruler (like the number line). With markings every cm (or inch, if you are stuck in the 19th century). Now, imagine the ruler stretches so all the marking are twice as far apart. The ruler is still infinitely long, but it has scaled by a factor of 2. (Or the "density" of the marks has fallen by half).

 

Does that help?

 

Yes, that's a better example, thank you. But still something about this infinitely long ruler bothers me. It reminds me of the light speed limit on the universe. Infinity could be the distance limit on the universe. To say you can have infinity times 2 or 3 means the same as infinity. I have this suspicion that when it comes to distance, infinities of all sorts are equivalent. For example, it may be that if: INF = Infinity and N = Any Number, then INF x N = INF. I've never heard this before so it's pure speculation and thanks for listening.

Edited April 10, 2016 by Airbrush

[Strange]

To say you can have infinity times 2 or 3 means the same as infinity. I have this suspicion that when it comes to distance, infinities of all sorts are equivalent. For example, it may be that if: INF = Infinity and N = Any Number, then INF x N = INF.

 

That is basically correct. (Although complicated by the fact that there are different infinities. In fact, an infinite number of them ...)

[David Levy]

How could it be that an infinite Universe would be created out of nothing?

 

In the following article it is stated:

http://arxiv.org/pdf/1404.1207v1.pdf

"Spontaneous creation of the universe from nothing"

So, if the current universe is as follow:

Try this for visualisation:
Currently our Observable Universe seems to be this big:--> O

 

Then this theory might be applicable for the following starting point of the Universe:

 

But from evidence (see previous in this thread) it's been expanding, and previously was this big:--> .

 

However, if the Universe is infinite:

But, The Universe might actually be infinite:
--> --- OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ---

 

 

Then, how could it be that an infinite starting point of the universe would be created out of nothing?

Which expanded from an infinite:
--> --- .................................................. ---

 

 

[Mordred]

Although this is a good article, this particular model conjecture doesn't imply an infinite universe.

 

The main reason is it requires rapid inflation from a Planck length.

 

Universe from nothing models though theoretically plausible, are typically finite. In many ways this model is a quantum variation of Bubble universe creation. Very similar to chaotic eternal inflation.

 

 

I personally know of no universe from nothing model that is considered infinite. Doesn't necessarily mean there isn't any.

I honestly can't see how the mechanism in this paper could be used for an infinite universe.

[Strange]

How could it be that an infinite Universe would be created out of nothing?

 

Note that no one is saying that the universe IS infinite, just that it could be.

Also, no one is saying that the universe WAS created from nothing, only that it could be. (And note that "nothing" in this case has the rather special, technical meaning of "false vacuum state". So not really nothing.)

[David Levy]

Thanks

 

Note that no one is saying that the universe IS infinite, just that it could be.

Also, no one is saying that the universe WAS created from nothing, only that it could be. (And note that "nothing" in this case has the rather special, technical meaning of "false vacuum state". So not really nothing.)

 

What do you mean by "false vacuum state"?

However, if the Universe is Infinite:

 

I personally know of no universe from nothing model that is considered infinite. Doesn't necessarily mean there isn't any.
I honestly can't see how the mechanism in this paper could be used for an infinite universe.

 

Does it mean that our current Theories don't cover this option?

So, do we need to "invent the wheel" - (Ignore the current mainstream Theories including the BBT), or we just need to find (as usual) a new patch to close the gape.

[pzkpfw]

... So, do we need to "invent the wheel" - (Ignore the current mainstream Theories including the BBT), or we just need to find (as usual) a new patch to close the gape.

Remember, the BBT doesn't cover the origin of the Universe. What it does cover, is pretty rock solid.

 

(It's like the difference between evolution and abiogenesis. People often confuse or combine the two. Evolution is very well known, the exact specific origin of life is much less certain.)

 

Note that my earlier visualisation post wasn't about the origin of the Universe.

[Strange]

What do you mean by "false vacuum state"?

 

It means that universe could be (or could have been) in an unstable state that was not the lowest energy state. If you imagine energy as the slope of a hill, then a ball will tend to roll all the way down to the lowest (ground) level. But there could be a ledge or plateau halfway down where things get stuck: they seem to be at ground level, but are not. That is equivalent to the false vacuum. A small push will send the ball rolling down to the true ground level. Similarly a small push (quantum fluctuation) could push the universe to a lower energy state. This would release a large amount of energy.

 

http://www.askamathematician.com/2012/07/q-what-is-the-false-vacuum-and-are-we-living-in-it/

https://en.wikipedia.org/wiki/False_vacuum

 

 

However, if the Universe is Infinite:

 

Does it mean that our current Theories don't cover this option?

 

No, it just means that Mordred is not aware of any theories that cover this option.

(Neither am I. But I have heard experts in the area say there is no reason why there couldn't be such a theory.)

 

So, do we need to "invent the wheel" - (Ignore the current mainstream Theories including the BBT), or we just need to find (as usual) a new patch to close the gape.

 

No. We don't have to have a theory for every combination of options. Some of them might not be possible. So, here you have the options:

 

(1a) The universe was created from nothing OR (1b) the universe was not created from nothing

(2a) The universe is finite OR (2b) the universe is infinite.

 

(Note that none of these are part of the big bang theory, currently)

 

So you have seen a theory that describes 1a + 2a.

There are also theories for 1b + 2a and 1b + 2b.

There may or may not be a theory for 1a + 2b. And maybe we don't need one.

Edited April 13, 2016 by Strange

[Mordred]

At least infinite theory theory using false vacuum related metrics.

 

The closest possibility would be the zero energy universe model. That particular variant may allow the possibility.

 

The metrics however require potential vs kinetic energy in a geometry. Curvature requires the use of pseudo tensors which GR advocates tend to frown upon.

 

http://www.google.ca/url?q=http://arxiv.org/pdf/gr-qc/0605063&sa=U&ved=0ahUKEwj598fEoIvMAhVUzWMKHeuPC-kQFggRMAA&usg=AFQjCNETzVlkxJseEroHw2ZaZsxV-vHoOg

 

It is another variant of universe from nothing. Though seems similar to the David posted there are differences in the actual metrics.

 

Least this is the closest possibility I've run across.

Edited April 13, 2016 by Mordred