Joe says  
I've recently read some papers on quantum cosmology and they all leave me with one question on my mind. If we describe the universe as a quantum system, then no outside observer can "collapse our wave function." Why, then, is the distribution of matter not mostly constant? Instead it is all grouped together into galaxies and even further into stars. Any thoughts? 

Total Topic Karma: 3   More by this Author 
jared.nance says 


i haven't read much on quantum cosmology, but why can't an outside observer collapse the wavefunction of the universe?  
 29 January, 2007 
Joe says 


From what I understand, making an observation collapses the wave function. And apparently you can't observe a system if you're a part of it.  
 29 January, 2007 
Dhruv Sharma says 


hey joe ur proposition looks very paradoxical but it has one very big problem. You havent specified in which state the wavefunction is basically in? you havent specified whether the wavefunction is in the momentum state or the position state. let me explain it to you a bit more. Well the collapse of the wavefunction is more specifically known as the StateVector Reduction and physicists usually know it as the Evolution Procedure "R". Impicit in the description of the timedevelopment of a wave packet is Schroedinger's Equation, which tells us how the wavefunction tractually evolves in time. in effect, what the equation tells us is that if we decompose psi(wavefunction) into momentum states then each of these individual components with a speed that is (c)squared divided by the speed of the classical particle having the momentum in question. i suggest you first clear your doubts conmcerning the Wavefunction and acquaint yourself with schrodinger's equation and then think about your question. 

 30 January, 2007 
Dhruv Sharma says 


This link shall surely clarify all your doubts http://www.damtp.cam.ac.uk/user/gr/public/qg_qc.html 

 30 January, 2007 
Dhruv Sharma says 


well your proposition was wrong in the first place. This is because the wave function does not collapse on an observation. Rather it collapses when you want to make a calculation and in simpler words, magnify it to the classical world. It is only and only the evolution procedure "R" that induces probabilities into QM.  
 31 January, 2007 
says 


Well here is  
 10 February, 2007 
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my proposition:  
 10 February, 2007 
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its not really a proposition  
 10 February, 2007 
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more like a question for you guys:  
 10 February, 2007 
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Huh.... I forgot what i was gonna say.  
 10 February, 2007 
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Anyways....  
 10 February, 2007 
says 


if yer reading my comments,  
 10 February, 2007 
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give me karma, and feel  
 10 February, 2007 
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free to post  
 10 February, 2007 
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comments.  
 10 February, 2007 
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clik on all of the karma stars.  
 10 February, 2007 
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thx. KARMA!!!  
 10 February, 2007 
