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Here's a neverending discussion.

Here we can post (fun)facts, happenings at the moment, last developments, personal opinions about the mysterious universe... anything that comes to your mind... it's endless!

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7 hours ago, Dude_wheresmycarbs said:

Here's a neverending discussion.

Here we can post (fun)facts, happenings at the moment, last developments, personal opinions about the mysterious universe... anything that comes to your mind... it's endless!

Ok here goes (I'm a Physics guy by education)

According to General Relativity, if the universe is 'flat' it must be infinite.  Recent measurements seem to indicate that the universe is indeed flat with about 99.5% probability.  This wasn't the case in my Uni days.  Back then the finite, unbounded idea seemed to be most popular IIRC.  Like the surface of the earth, finite but no edge, except with more dimensions.

So now though it looks like the universe is flat and infinite according to our current understanding.  If this is the case, then it's a mathematical certainty there is another YOU somewhere else in the universe - seriously.  Mind = blown.

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My issue with infinite is we know the universe started from the "big bang"  we also know it expanded from there and continues to expand.  Based on that logic it would be impossible to call it infinite as it would be larger today than yesterday thus yesterday when we called it infinite we would be incorrect.

T

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18 minutes ago, tedtrushbodyathletica said:

My issue with infinite is we know the universe started from the "big bang"  we also know it expanded from there and continues to expand.  Based on that logic it would be impossible to call it infinite as it would be larger today than yesterday thus yesterday when we called it infinite we would be incorrect.

T

Ok, admittedly, I really digging deep into the memory archives here...

The concept of infinity in and of itself is a difficult concept.  For example (IIRC) the number of points on a line between say 1 and 2 is infinite.  Also the number of points on a line between 1 and 10 is also infinite.  Is the second one larger than the first?  Actually no it isn't - go figure.  That being said, some infinities are larger than others (ones that include irrational numbers I think is one example).  Messes with the mind.

The screwy thing about the expanding universe is that it doesn't really fit the model of the big bang starting from a point in traditional 3-D space, then 'stuff' just spreading out.  It's actually space itself that's expanding, not just that things are moving further apart.  Every point in space 'appears' to be the centre of expansion - which makes sense if it's actually space that's expanding.  We do see a universe 'size', but this is just the observable universe.  Theoretically, if we transported to the most distant galaxy we can see now, we'd see a similar observable universe, but with 'other' stuff that we can't see from here - and on and on to infinity.

Brain hurts thinking about it.

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12 hours ago, tedtrushbodyathletica said:

My issue with infinite is we know the universe started from the "big bang"  we also know it expanded from there and continues to expand.  Based on that logic it would be impossible to call it infinite as it would be larger today than yesterday thus yesterday when we called it infinite we would be incorrect.

T

To take this thought a bit further...

Everything is constantly expanding.  So tomorrow is bigger than today etc.  But that technically applies to the matter spreading out.  What exactly is it spreading out into?  Matterless universe.  

Or, nothing exists until the universe expands into it.  In which case there is an outer limit.  Therefore not infinite because it can be defined.

 

 

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5 hours ago, KetoMuscles said:

To take this thought a bit further...

Everything is constantly expanding.  So tomorrow is bigger than today etc.  But that technically applies to the matter spreading out.  What exactly is it spreading out into?  Matterless universe.  

Or, nothing exists until the universe expands into it.  In which case there is an outer limit.  Therefore not infinite because it can be defined.

 

 

Allegedly there is nothing to expand into, the celestial bodies are just moving further away from each other. This doesnt make any sense to me honestly because if they are moving away from each other the space between them is getting bigger and bigger and for that more space is needed... so I'm confused 🤔🤨 @BobTheOldLifter psysics guy?!

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2 hours ago, Dude_wheresmycarbs said:

Allegedly there is nothing to expand into, the celestial bodies are just moving further away from each other. This doesnt make any sense to me honestly because if they are moving away from each other the space between them is getting bigger and bigger and for that more space is needed... so I'm confused 🤔🤨 @BobTheOldLifter psysics guy?!

That's right.  It's space itself that is expanding everywhere.  A 2D example would be an inflating ball where points on the surface continue to spread out.

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12 hours ago, KetoMuscles said:

 But that technically applies to the matter spreading out.  What exactly is it spreading out into?  Matterless universe.  

It doesn't quite work that way.

The idea (as impossible or screwy as it sounds) is that the universe was always infinite - at least since an instant after the big bang.  What's been happening after the big bang is that space itself is expanding (and the universe becoming less dense), which is different (but tough to imagine) than things just flying away from each other in 3 dimensions into empty space.

So, if the universe was always infinite, but it's getting bigger?? WTF??

Yes...

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On 8/9/2019 at 10:53 AM, Pump_And_Hump said:

The most important question is what is happening behind that end...

Nothing... according to science. If the universe is getting bigger and stars and planets are moving further away from eachother then there must be something outside... something like a baloon in a box.

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1 hour ago, Dude_wheresmycarbs said:

Nothing... according to science. If the universe is getting bigger and stars and planets are moving further away from eachother then there must be something outside... something like a baloon in a box.

No, not quite.  The galaxies seem to be moving away from each other because space itself is expanding, not because they're moving away from each other inside a fixed space - sounds like it's the same thing, but it's not.  I believe the current view (although I'm sure it's not unanimous) according to the evidence we have is that the universe is infinite.  By definition, there is no 'outside'.  Kinda like asking where the end of the earth is.  The question doesn't make sense b/c there is no end to the surface of a sphere, and it's not that there is 'nothingness' outside of the universe, it's that there is no outside.

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On 8/13/2019 at 6:19 PM, BobTheOldLifter said:

No, not quite.  The galaxies seem to be moving away from each other because space itself is expanding, not because they're moving away from each other inside a fixed space - sounds like it's the same thing, but it's not.  I believe the current view (although I'm sure it's not unanimous) according to the evidence we have is that the universe is infinite.  By definition, there is no 'outside'.  Kinda like asking where the end of the earth is.  The question doesn't make sense b/c there is no end to the surface of a sphere, and it's not that there is 'nothingness' outside of the universe, it's that there is no outside.

but it is very confusing.... what is infinity? there must be an end point somewhere...

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Yeah, one idea was that the universe was closed but unbounded.   I think that is the correct terminology.  Where three dimensional space is wrapped around a fourth so if you travelled far enough in one direction you'd end up back where you started.  Similar to the surface of the earth (2D) wrapped around a 3D sphere.  Not infinite,  but unbounded (no edge). This makes sense to me,  but as I understand it,  current evidence points to infinite with an apparent high degree of certainty. 

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Hahaha.  Like arguing with a woman.  You think you're getting somewhere but the further you travel the more you realize you're back where you started.  And their capacity to carry on a 2 dimensional argument is infinite.

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1 hour ago, KetoMuscles said:

Hahaha.  Like arguing with a woman.  You think you're getting somewhere but the further you travel the more you realize you're back where you started.  And their capacity to carry on a 2 dimensional argument is infinite.

Lol! Never thought of it that way!

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