I read "Why Occam's Razor" tonight after posting my last response (despite having a Federal court brief begging for attention).  I didn't have time to wade through the technical parts  very thoroughly, but in general I found it a very good summary of many of the topics we have been frequently discussing on this list. 

I also re-read (skimmed) Nick Bostrom's "are you living in a simulation" paper tonight, and it occurs to me if you add his argument to MWI, you get the inevitable conclusion that we are simulated, which I guess is actually a similar concept to Marchal (though Marchal goes much further in attempting to derive QM, etc. from this).   One difference being that Marchal argues the UTM does not need to actually exist physically, but as you state in your paper if I read/remember correctly, the UTM would exist both as mathematical and physical structure.

This then leads back to questions about the differences between the mathematical and physical structure; if any.  With consideration that any given area of the multiverse is inevitably and eternally being simulated by another area, I thereby come full circle and see what Marchal is saying - there is no need to even consider what we refer to as the physical.  I wonder if, considering Godel, we are forever doomed to walk around in circles like this....

Danny Mayes



many seem to bend over backwards to say you do not actually have to have the UTM exist physically


Russell Standish wrote:
On Thu, May 12, 2005 at 12:40:10AM -0400, danny mayes wrote:
  
Russell,

When I stated in the original reply that pulling information out of 
other worlds in the MWI context was prohibited by physics, I was 
referring to information about those universes.  As I stated, obviously 
you can create a superposition to utilize  processing power in other 
universes, but you can't take from this information about the 
universes/worlds you are utilizing.  Therefore, the original concept of 
people "seeing" into other universes seems to be prohibited by the laws 
of physics.

As I understand it, the mathematics of Hilbert space prohibits 
inter-world communications because the attempt to remove information 
from Hilbert space causes decoherence, destroying reversibility.  "Any 
Hilbert space accessible from more than one world line must be a 
timeless place, in which we can leave no permanent mark." - Colin Bruce
    

Part of the problem is in assuming that all quantum worlds are
disjoint from each other, when it is clear this is not the case. Take
an example Multiverse that has one spin 1/2 particle in it. Clearly,
it consists of two worlds, one which has spin +1/2\hbar, the other
with spin -1/2\hbar in the z-direction. However, this Multiverse also
has another two worlds in it, one with spin +1/2\hbar and one with
-1/2\hbar, however this time in the x-direction. And so on. All these
worlds exist. By choosing to measure the particle in the x-direction,
I get information from both of the "+1/2-" and "-1/2 in the
z-direction" worlds, hence there is a form of information flow between
worlds.

Nevertheless, there is, as you say, no information flow between
decohered worlds.

  
Also, I'm interested in your TIME hypothesis.  Could you refer me to a 
source for information, or summarize for me? 

    

I initially raised it my paper "Why Occam's Razor", and have discussed
it a few times on the everything list. Try doing a search on
time+russell+standish on the everything list archive.

As a summary, it states that an observer must experience a time
dimension, within which e can process information, and bring disparate
facts together for comparison. About the only requirement of this time
object is that it must have topological dimension at least 1. I
usually assume that it is at least a "time scale" - see the Nohner and
Peterson's book:

@Book{Bohner-Peterson01,
  author =	 {Martin Bohner and Allan Peterson},
  title = 	 {Dynamic Equations on Time Scales},
  publisher = 	 {Birkh\"auser},
  year = 	 2001,
  address =	 {Boston}
}

Cheers


  
Danny Mayes

    

  

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