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Nongeometric approach to gravity impossible? 
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#37
Feb2812, 05:42 PM

P: 381

Why didn't you answer this question "2. Can Loop Quantum Gravity be formulated as spin2field in flat spacetime? Or does LQG stay valid only if spacetime is actually curved?" anyone else knows the answer? 


#38
Feb2812, 06:12 PM

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#39
Feb2812, 06:22 PM

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#40
Feb2812, 06:59 PM

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#41
Feb2812, 07:03 PM

P: 381

"Graviton propagator in loop quantum gravity" If you have read it already before, please comment on it on the important issues related to our discussions. Thanks. 


#42
Feb2812, 07:05 PM

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#43
Feb2812, 11:23 PM

P: 381

btw.. how do you model Big Bang Expansion using spin2 field on flat spacetime? Anyone got an idea?



#44
Feb2812, 11:27 PM

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Weinberg exhibits harmonic coordinates for the FRW universe in his text book.
I'm not sure whether the positive cosmological constant changes things. 


#45
Feb2812, 11:51 PM

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#46
Feb2912, 12:10 AM

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There's a famous rewrite of the Minkowski metric as expanding space called the Milne universe. It's not relevant to our universe, since it has no matter (in GR, flat spacetime has no matter).
The FRW universe is expanding space with matter, and corresponds to curved spacetime. 


#47
Feb2912, 12:14 AM

P: 381

if flat spacetime has no matter, then how does the spin2 field in flat spacetime expand with matter? I can't find anything in the internet from goggling "expanding flat spacetime". Hope you have some references. 


#48
Feb2912, 12:18 AM

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#49
Feb2912, 12:25 AM

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#50
Feb2912, 12:33 AM

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#51
Mar112, 12:11 AM

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#52
Mar112, 12:32 AM

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#53
Mar112, 12:34 AM

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#54
Mar112, 12:40 AM

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