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  Reply # 1621488 2-Sep-2016 16:01
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Rikkitic:

 

It seems to be generally accepted that the Universe is expanding. In that case I don't see how it can be infinite. I think what confuses people is that space is also expanding, not just the distances between stuff in it. The Universe is not expanding inside a larger volume,  like a container of some kind that it is filling up, but it is the expansion. This is hard to grasp. I still see this as the multi-dimensional balloon model, with the centre everywhere on the surface and nothing 'inside'. The reason you can't travel around the sphere and end up back where you started is that the expansion happens faster than you could move at the speed of light, so you would never be able to complete a circumnavigation.

 

 

 

 

Universe and space are different?  The Universe is supposed to be everything. Matter that we see, matter that we dont, and the void inbetween.

 

There cant be a larger volume as the Universe is everything.

 

If the balloon model is correct, the Universe is a plane, wrapped as an expanding shere with us on the outer thick surface

 

The expansion isnt at the speed of light, I recall some large number of planetary expansion, or the speed that matter is speeding away from the big bang point. If light is the expansion speed is the speed of light (you cant get faster) then is the overll void infinite and the universe is just where matter and light is?

 

 




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  Reply # 1621490 2-Sep-2016 16:07
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Paul1977:

 

tdgeek:

 

4th dimension. Hmmm. If the universe is that skin I guess the thickness of it is the distance between how far light has travelled for 13.8 billion years, and the inner skin is how far hard matter has travelled?

 

If so, the inner is part of the universe also, but its completely void as everything has travelled away from the big bang. and that shows the universe is not infinite. But it is IMO still the sheer except it is empty space, devoid of matter and light

 

 

By removing a dimension to represent the universe as the surface of the balloon it would have no thickness (if you mean the thickness of the rubber, which you may not). In the real world the rubber has depth, but for the purpose of the analogy it does not.

 

I'm not sure how you would represent how far light has traveled since the Big Bang. I guess it would be the circumference of the inflated balloon?

 

The air inside and outside the balloon would not be considered part of our 3 dimensional universe.

 

 

Depth yes. The outer of the plane, the furtherest expansion is where light has got to, the inner is where matter has got to as that cannot travel at the speed of light

 

The balloon inside that must be the universe, as empty space, a void, as everything has travelled out from there

 

Cannot be anything past the outer where light has got to, as the universe is expanding. Bit of a paradox there

 

To me the universe is all the balloon but only hard matter and light exist in the outer plane

 

 


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  Reply # 1621528 2-Sep-2016 17:11
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tdgeek:

 

Paul1977:

 

tdgeek:

 

4th dimension. Hmmm. If the universe is that skin I guess the thickness of it is the distance between how far light has travelled for 13.8 billion years, and the inner skin is how far hard matter has travelled?

 

If so, the inner is part of the universe also, but its completely void as everything has travelled away from the big bang. and that shows the universe is not infinite. But it is IMO still the sheer except it is empty space, devoid of matter and light

 

 

By removing a dimension to represent the universe as the surface of the balloon it would have no thickness (if you mean the thickness of the rubber, which you may not). In the real world the rubber has depth, but for the purpose of the analogy it does not.

 

I'm not sure how you would represent how far light has traveled since the Big Bang. I guess it would be the circumference of the inflated balloon?

 

The air inside and outside the balloon would not be considered part of our 3 dimensional universe.

 

 

Depth yes. The outer of the plane, the furtherest expansion is where light has got to, the inner is where matter has got to as that cannot travel at the speed of light

 

The balloon inside that must be the universe, as empty space, a void, as everything has travelled out from there

 

Cannot be anything past the outer where light has got to, as the universe is expanding. Bit of a paradox there

 

To me the universe is all the balloon but only hard matter and light exist in the outer plane

 

 

 

 

I think we are just defining "universe" differently. I think of the universe as the 3 dimensional universe that we are able to perceive. To me anything outside of our 3D universe must be in a higher dimension. It sounds like you define the universe as absolutely everything in every dimension. I don't know which is the generally excepted term.

 

But things can be infinite without taking up everything. Imagine a line that extends forever in both directions. It is surely infinite as it goes on forever, but it clearly does not take up all available space.

 

We may have also taken the balloon analogy further than it was intended. I don't know that it was meant to demonstrate anything other that the concept of equal expansion everywhere that has no centre. It becomes basically impossible to visualize when we add the extra dimension back, as we simply can't visualize the idea of a 4th physical dimension. It would be like a person who has only ever seen in black and white trying to visualize what colour was.


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  Reply # 1621547 2-Sep-2016 17:26
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MikeAqua:

 

How do you treat infinity in arithmetic?

 

Infinity - Infinity = what

 

Are two separate infinities the same size?

 

Can you even have two separate infinities? One infinity should spatially preclude a 2nd infinity existing?

 

Or can infinities nest like Russian dolls?

 

After all everything should fit in an infinity?

 

 

For the love of me I cannot recall the name of the book I read while I was at high school. I remember the cover is brown and it put forward arguments from Godel and others with regards to the concept of 'infinity'. You can try reading "Everything and More: A Compact History of Infinity" by David Foster Wallace. He attempted to explain infinity - but you will find that there are more questions than answers at the end. Unfortunately David committed suicide, so there will be no follow up series from him.

 

If we were to use logic - 'infinity' is absurd. Imagine this, the prime minister needs permission from his adviser A before he can approve the funding. The adviser A needs to ask adviser B for permission. Adviser B needs to ask Adviser C for permission. Adviser C needs to ask Adviser D for permission - and imagine if you have an infinite number of advisers, can the prime minister ever approve the funding? 

 

This is why in mathematics - infinity is usually used to denote unbounded limit or infinite series (not part of the calculation itself).








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  Reply # 1621679 2-Sep-2016 21:51
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Paul1977:

 

tdgeek:

 

Paul1977:

 

tdgeek:

 

4th dimension. Hmmm. If the universe is that skin I guess the thickness of it is the distance between how far light has travelled for 13.8 billion years, and the inner skin is how far hard matter has travelled?

 

If so, the inner is part of the universe also, but its completely void as everything has travelled away from the big bang. and that shows the universe is not infinite. But it is IMO still the sheer except it is empty space, devoid of matter and light

 

 

By removing a dimension to represent the universe as the surface of the balloon it would have no thickness (if you mean the thickness of the rubber, which you may not). In the real world the rubber has depth, but for the purpose of the analogy it does not.

 

I'm not sure how you would represent how far light has traveled since the Big Bang. I guess it would be the circumference of the inflated balloon?

 

The air inside and outside the balloon would not be considered part of our 3 dimensional universe.

 

 

Depth yes. The outer of the plane, the furtherest expansion is where light has got to, the inner is where matter has got to as that cannot travel at the speed of light

 

The balloon inside that must be the universe, as empty space, a void, as everything has travelled out from there

 

Cannot be anything past the outer where light has got to, as the universe is expanding. Bit of a paradox there

 

To me the universe is all the balloon but only hard matter and light exist in the outer plane

 

 

 

 

I think we are just defining "universe" differently. I think of the universe as the 3 dimensional universe that we are able to perceive. To me anything outside of our 3D universe must be in a higher dimension. It sounds like you define the universe as absolutely everything in every dimension. I don't know which is the generally excepted term.

 

But things can be infinite without taking up everything. Imagine a line that extends forever in both directions. It is surely infinite as it goes on forever, but it clearly does not take up all available space.

 

We may have also taken the balloon analogy further than it was intended. I don't know that it was meant to demonstrate anything other that the concept of equal expansion everywhere that has no centre. It becomes basically impossible to visualize when we add the extra dimension back, as we simply can't visualize the idea of a 4th physical dimension. It would be like a person who has only ever seen in black and white trying to visualize what colour was.

 

 

Ive okay seethe balloon ones, that was to explain how stars etc speed away from each other during expansion.

 

Lets take a breath. here is the dictionary meaning:

 

noun

 

 

 

     

  1.  

     

    1

     

     

     

    all existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light years in diameter and contains a vast number of galaxies; it has been expanding since its creation in the Big Bang about 13 billion years ago.

     

     

     

    The diameter is now 91 billion lightyears I read recently. 

     

     

     

     

     

    SHAPE.

     

    Its a sphere, a saddle or flat. The consensus seems to be flat. That dispels that I read it expands in all directions

     

     

     

     


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  Reply # 1621685 2-Sep-2016 22:06
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tdgeek:

 

SHAPE. Its a sphere, a saddle or flat. The consensus seems to be flat. That dispels that I read it expands in all directions

 

 

Isn't that kind of like saying it's black, or white, or green? Doesn't seem very definitive to me.

 

  





I reject your reality and substitute my own. - Adam Savage
 




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  Reply # 1621695 2-Sep-2016 22:20
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Rikkitic:

 

tdgeek:

 

SHAPE. Its a sphere, a saddle or flat. The consensus seems to be flat. That dispels that I read it expands in all directions

 

 

Isn't that kind of like saying it's black, or white, or green? Doesn't seem very definitive to me.

 

  

 

 

Talk to all scientists. Based on density, gravity and expansion momentum, these three shapes are the results of the three possible answers.

 

Sphere. Expansion will stop, and contract

 

Flat. Gravity and expansion are almost equal, expansion will stop in an infinite length of time, so it will expand forever

 

Saddle. Momentum exceeds gravity so expansion will continue forever.

 

http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question35.html

 

Representative of any search on the shape of the Universe.

 

 


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  Reply # 1621821 3-Sep-2016 09:51
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tdgeek:

Paul1977:


tdgeek:


Paul1977:


tdgeek:


4th dimension. Hmmm. If the universe is that skin I guess the thickness of it is the distance between how far light has travelled for 13.8 billion years, and the inner skin is how far hard matter has travelled?


If so, the inner is part of the universe also, but its completely void as everything has travelled away from the big bang. and that shows the universe is not infinite. But it is IMO still the sheer except it is empty space, devoid of matter and light



By removing a dimension to represent the universe as the surface of the balloon it would have no thickness (if you mean the thickness of the rubber, which you may not). In the real world the rubber has depth, but for the purpose of the analogy it does not.


I'm not sure how you would represent how far light has traveled since the Big Bang. I guess it would be the circumference of the inflated balloon?


The air inside and outside the balloon would not be considered part of our 3 dimensional universe.



Depth yes. The outer of the plane, the furtherest expansion is where light has got to, the inner is where matter has got to as that cannot travel at the speed of light


The balloon inside that must be the universe, as empty space, a void, as everything has travelled out from there


Cannot be anything past the outer where light has got to, as the universe is expanding. Bit of a paradox there


To me the universe is all the balloon but only hard matter and light exist in the outer plane


 



I think we are just defining "universe" differently. I think of the universe as the 3 dimensional universe that we are able to perceive. To me anything outside of our 3D universe must be in a higher dimension. It sounds like you define the universe as absolutely everything in every dimension. I don't know which is the generally excepted term.


But things can be infinite without taking up everything. Imagine a line that extends forever in both directions. It is surely infinite as it goes on forever, but it clearly does not take up all available space.


We may have also taken the balloon analogy further than it was intended. I don't know that it was meant to demonstrate anything other that the concept of equal expansion everywhere that has no centre. It becomes basically impossible to visualize when we add the extra dimension back, as we simply can't visualize the idea of a 4th physical dimension. It would be like a person who has only ever seen in black and white trying to visualize what colour was.



Ive okay seethe balloon ones, that was to explain how stars etc speed away from each other during expansion.


Lets take a breath. here is the dictionary meaning:


noun
 



  1. 1


    all existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light years in diameter and contains a vast number of galaxies; it has been expanding since its creation in the Big Bang about 13 billion years ago.
     
    The diameter is now 91 billion lightyears I read recently. 
     
     
    SHAPE.
    Its a sphere, a saddle or flat. The consensus seems to be flat. That dispels that I read it expands in all directions





You left he word observable off your 13 billion number. In physics, its the little words that have the most meaning :)




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  Reply # 1621896 3-Sep-2016 13:00
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TwoSeven:
You left he word observable off your 13 billion number. In physics, its the little words that have the most meaning :)

 

 

 

True, but at least I used billion, instead of million as I did earlier :-)


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  Reply # 1624389 6-Sep-2016 09:18
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I was watching some interesting material yesterday on empty space.  One of the consequences of quantum theory is that empty space contains huge amount of energy.  This is because quantum particles behave like waves that travel very long distances.  This dispersed energy is postulated as the reason the universe is  expanding and that expansion is accelerating.

 

Enough energy supposedly exists in space to boil all the matter in the universe.  But it doesn't.  There seem to be three main theories to explain why not.

 

1) Super symmetry: for very particle their is a mirror image s-particle. Waves of energy emitted by these particles cancel each other out

 

2) Dark energy: offsets regular energy

 

3) Space can exist in multiple states: space dropped into its current state from a higher energy state and will drop into an even lower energy state.  The kinds of particles we are made of can only exist in space's current state.  If super symmetry is true, then the current state of space will persist for 20B years.  If it doesn't we only have about 1B years left.  Scary stuff!





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  Reply # 1624430 6-Sep-2016 09:57
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I saw the same documentary. Considering we have only been around for about 2 million years, 1 billion sounds fairly generous. Of course that is assuming we are the only ones who care.

 

 





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  Reply # 1624556 6-Sep-2016 12:46
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Rikkitic:

 

I saw the same documentary. Considering we have only been around for about 2 million years, 1 billion sounds fairly generous. Of course that is assuming we are the only ones who care.

 

 

 

 

Humans are only 200,000 years old, Neanderthals about 600,00 years. We are quite young in the grand scheme of things


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  Reply # 1624614 6-Sep-2016 14:24
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tdgeek:

 

Rikkitic:

 

I saw the same documentary. Considering we have only been around for about 2 million years, 1 billion sounds fairly generous. Of course that is assuming we are the only ones who care.

 

 

 

 

Humans are only 200,000 years old, Neanderthals about 600,00 years. We are quite young in the grand scheme of things

 

 

He who always has to have the last word. I think the human evolutionary line is believed to have started around 2.5 million years ago, if I am not mistaken. Modern humans, as in Homo Sapiens, are indeed more recent but I was referring to humanity in general. 

 

 





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  Reply # 1624616 6-Sep-2016 14:28
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I stand corrected. Apparently human evolution is considered to have begun about 6 million years ago. I thought it was more recent.

 

 





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  Reply # 1624621 6-Sep-2016 14:39
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Rikkitic:

 

I stand corrected. Apparently human evolution is considered to have begun about 6 million years ago. I thought it was more recent.

 

 

 

 

If you want to be pedantic, you can go back eons before that. You mentioned humans

 

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