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The Universe  infinite or not ? 
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#37
May1111, 01:07 AM

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infinity loses meaning nestled amongst a multiverse of infinities, imo  aside from the fact the concept of infinity is unmeaningful to begin with. Everything in nature has relational meaning.



#38
May1111, 05:08 PM

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Infinity does not exist.
Let me phrase it the right way, to humans infinity can not exist for any physical reality, because of our sensory systems. 


#39
May1111, 05:24 PM

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FAQ: Is the universe finite, or is it infinite?
Standard cosmological models come in two flavors, open and closed. The open type has negative spatial curvature and infinite spatial volume. The closed one has positive curvature and finite spatial volume; spatially, it is the threedimensional analog of a sphere. Since both types are mathematically selfconsistent solutions to the Einstein field equations, the finiteness or infiniteness of the universe is something that cannot be determined by solely logic but only by observation. Current observations of the cosmic microwave background's anisotropy show that our universe is very nearly spatially flat (on the cosmological scale). If it is exactly flat, then it is a special case lying between the more general open and closed cases. The flat case has infinite volume. However, the range of uncertainty in the curvature is wide enough to be consistent with either positive or negative curvature, so right now the finiteness or infiniteness of the universe is an open question. Sometimes people use the word "universe" when they really mean "observable universe." The observable universe is finite in volume because light has only had a finite time to travel since the Big Bang. 


#40
May1111, 10:36 PM

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Good summary, bcrowell. An FAQ would be useful with a decent index.



#41
May1111, 10:50 PM

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The European Space Agency (ESA) Science and Technology: Glossary



#42
May1211, 04:30 AM

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#43
May1211, 08:23 AM

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This question may be the final unanswerable  obviously the OU is finite and measurable, anything outside of our OU can never be quantified. Assuming the Universe is spacially flat and homogeneous then cosmological models dictate an infinite size along its x,y,z axis.
However does time factor into this? As the second law of thermodynamics dictates the arrow of time moves only forwards then when the universe approaches the end of its life  as I understand it once matter and energy becomes seperated and diffuse to the point the universe is in final heat death? Is this plausable given infinite energy and matter states? If something expands inifinitely then while it is not infinite at any given moment it will expand to an an infinite size over infinite time but is this relevant as cosmo models indicate the final end of the universe will be a heat death? 


#44
May1611, 12:33 AM

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Olber's paradox refutes the infinitely old, spacious and star filled universe idea. The CMB refutes the old wives tale of infinite age all on its own.



#45
May1611, 12:50 AM

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#46
May1611, 03:34 AM

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How can anything outside the observable universe ever be quantified? I strongly disagree. Perhaps the source of our disagreement resides in the definition of what constitutes 'observable'.



#47
May1611, 12:22 PM

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Mutsi brought up Dark Matter. I'd like to present the lastest about it. April 14, 2011 from the Weizmann Institute of Science:



#48
May1611, 04:04 PM

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Also while we can measure spatial curvature the degree of error still lends to pos,neg or flat curvature. 


#49
May1711, 07:30 AM

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Infinity question: If we headed directly into space traveling at many times the speed of light (ignoring for a moment that you can't travel that fast), maintaining exactly the same course for the whole trip, would or could we eventually find ourselves heading back to Earth?



#50
May1711, 08:28 AM

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If U was an nsphere then yes. I am sure someone can elaborate further but as this is off topic you may be better starting a fresh thread. 


#51
May1711, 08:35 AM

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#52
May1711, 01:52 PM

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#53
May1711, 05:53 PM

P: 366

Is this incorrect? A little more explanation would be nice. Thanks 


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