Register to reply 
Nongeometric approach to gravity impossible? 
Share this thread: 
#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

Sci Advisor
P: 8,802




#39
Feb2812, 06:22 PM

P: 381




#40
Feb2812, 06:59 PM

Sci Advisor
P: 8,802




#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

Sci Advisor
P: 8,802




#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

Sci Advisor
P: 8,802

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

P: 381




#46
Feb2912, 12:10 AM

Sci Advisor
P: 8,802

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

Sci Advisor
P: 8,802




#49
Feb2912, 12:25 AM

P: 381




#50
Feb2912, 12:33 AM

Sci Advisor
P: 8,802




#51
Mar112, 12:11 AM

P: 381




#52
Mar112, 12:32 AM

Sci Advisor
P: 8,802




#53
Mar112, 12:34 AM

P: 381




#54
Mar112, 12:40 AM

Sci Advisor
P: 8,802




Register to reply 
Related Discussions  
A Geometric Approach to Differential Forms by David Bachman  Differential Geometry  175  
A Geometric Approach to the Riemann Hypothesis  Linear & Abstract Algebra  0  
Special Relativity  geometric approach?  Science & Math Textbooks  2  
A Geometric Approach to the Standard Model, Greg Trayling  High Energy, Nuclear, Particle Physics  0  
A New Approach in Quantum Gravity  Beyond the Standard Model  0 