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How do we know space is not infinite? 
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#55
Sep2611, 04:46 PM

PF Gold
P: 6,325

[QUOTE=Tanelorn;3524331] ... I think that the observable universe is small compared to the whole universe because the CMBR is so flat in every direction implying homogeneity.QUOTE]
I too think I now get what Chris is saying (and agree w/ him that it is unlikely), but I do NOT get the statement above. Why does homogeneity limit his suggestion in any way, or suggest that the U is much bigger than the OU ? 


#56
Sep2611, 05:46 PM

P: 727

Phinds, ever since reading Penrose's estimate that the observable universe is just ~1031 the size of the whole universe, I have been trying to build a mental picture of such a system.
It is pretty funny to think that the entire observable universe is an insignificant part of the whole universe. 


#57
Sep2611, 08:32 PM

PF Gold
P: 6,325

I'm still interested in hearing your answer to my question of why you think the CMB homogeniaty implies anything about the size of the U beyond the OU. 


#58
Sep2711, 02:21 AM

P: 38




#59
Sep2711, 05:55 AM

Mentor
P: 11,869




#60
Sep2711, 08:45 AM

P: 727




#61
Sep2711, 09:14 AM

PF Gold
P: 6,325




#62
Sep2711, 09:17 AM

P: 727

ok glad to help. Lots of if and buts there and a cynic might say that it still needs to be proved.
The only truth that counts is the one that can be scientifically proved. 


#63
Sep2811, 01:38 AM

P: 59

Infinity, in and of itself, is not a number. There are finite numbers (ordinals), and transfinite ordinals. There are finite sets, and infinite sets. The first transfinite ordinal is omega "w"...which can be considered the next larger number after ALL the Natural numbers. It is the order type of the Set of all numbers preceding it, which is the Set of Natural numbers. In accordance with Cantor's ordinal arithmetic, w + 1 = w is NOT true. w + 1 is the next ordinal which succeeds w. On the other hand 1 + w = w IS true. So, a well ordered listing of ordinals that include the Naturals and extend to the first three transfinite ordinals would be: { 0, 1, 2, 3,..., w, w+1, w+2 } 


#64
Sep2911, 09:19 PM

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#65
Sep3011, 12:37 PM

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#66
Sep3011, 01:23 PM

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#67
Oct111, 12:14 AM

P: 186

Maybe spacetime’s a compact Lorentzian manifold



#68
Oct811, 05:22 AM

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#69
Oct811, 05:53 AM

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#70
Oct811, 07:55 AM

PF Gold
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#71
Oct811, 10:05 AM

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#72
Oct811, 02:07 PM

P: 191

IF our universe is infinite, would that rule out the possibility that other universes exist?



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