Re: why can't we erase information?

2006-05-04 Thread Jesse Mazer

Tom Caylor wrote:


Actually, in reviewing the definition of Turing machine (it's been over
2 decades since I studied it) I agree with you.  The Turing machine
leaves behind a memory of its past through its writes to the tape.
Maybe I don't understand what Wei Dai was saying with his setting of
the head back to the start of the tape.  In order to get back to the
exact beginning *state* the Turing Machine would have to be instructed
to do an inverse of all of the writes it has done and then go back to
the start of the tape.

But there is not always a unique inverse. There may be two distinct previous 
states A and B which would lead to the same state C on the next step--in 
this case the dynamics are not reversible.

Jesse



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Re: why can't we erase information?

2006-05-04 Thread Bruno Marchal


Le 03-mai-06, à 16:34, Tom Caylor a écrit :


 I am beside myself  ;)  Perhaps the interactive step-by-step approach
 that you've used in the past would be easier for you and more
 profitable for us.


Thanks for the suggestion. I will give it a try asap.






 Speaking of impasse with myself and diagonalization, a thought
 occurred to me that an instruction that erases information, like a
 Turing machine goto statement (e.g. Wei Dai's go to the beginning 
 of
 the tape instruction)


 ? Why a goto should erase anything ?


 Actually, in reviewing the definition of Turing machine (it's been over
 2 decades since I studied it) I agree with you.  The Turing machine
 leaves behind a memory of its past through its writes to the tape.
 Maybe I don't understand what Wei Dai was saying with his setting of
 the head back to the start of the tape.  In order to get back to the
 exact beginning *state* the Turing Machine would have to be instructed
 to do an inverse of all of the writes it has done and then go back to
 the start of the tape.


OK. Then it is not just a goto, it is a complete application of a 
reversible process. This will work only if you are using a reversible 
turing machine in the first place (like the one discover first by Hao 
Wang, Interesting work are those of Fredkin and Toffoli, and then the 
entire field of quantum computing).





 I believe that in the meta system, being open requires a paradigm
 shift in the meaning of understanding.


This is not entirely clear for me.



 If we just stick to our
 reductionist meaning of understanding, then we are still closed and we
 haven't really gone out of the system.  This new sense of understanding
 is what allows us to not go into an infinite or circular regress.  It
 is what allows us to assign *true* meaning in the first place.


I propose we come back on this after I (try to) explain a little bit 
more on diagonalization. I have a problem with the word reductionism. 
For some people number or machine are reductionist concepts, but I 
think that this opinion stems from a reductionist conception of number 
or machine.
Surely some new understanding of machine or number is needed.




 But now, I must confess (!) that I am discovering that if the Riemann
 critical zeros really describe a spectrum related to a quasi (?)
 classical chaotic regime---as it can be suspected from experimental
 (but still purely mathematical!) evidences---then I could imagine that
 the prime numbers could eventually describe not only a Universal Wave
 Function (even if only by pieces but the first person doesn't care as
 far as those pieces have a positive density) but would also describe a
 sort of universal wave reduction like if an absolutely external
 observer was included freely in the number's gift !
 So, recursion theory (computer science) allows internal metas, but
 primes, by their so much irregular behavior could still provide an
 apparent reduction justifying some external metas. Weird. I tend not 
 to
 believe in it, though.

 Who did invite the primes to the banquet?

 Just thinking aloud. Perhaps my Spring Riemann fever ...


 Wishful, but good, thinking in my view.  I take your I tend not to
 believe in it, though as saying that you don't think it's worth
 investing a lot of your resources in pursuing it.




I didn't say that. But we still don't know if Riemann hyp. is true and 
the field is technical. Clearly something happens there.






  I tend to think that
 pursuing anything is worth it if it allows us to see in a new way why
 it is closer or further away from reality.  The theory is that we can
 use these experiences to formulate a viewpoint of reality that is
 closer and closer to reality.


Maybe.




  Believing in this theory is actually an
 act of faith in the goodness of reality that goes beyond what evolution
 can explain.  I use the word goodness over and above
 understandability.  If reality is understandable *by us* in any way
 close to the aspirations of the Everything List, then I feel pulled to
 express this as, Someone out there is truly being good to us.


Plotinus says so but (from a 3 person point of view) I am not yet 
convinced. There are some evidences but we must try to be cold on 
this and to beware wishful thinking, and then we should also not to 
exaggerate in the opposite direction.
We can have doubt when seeing kind people suffering a lot, and remember 
that the Platonists link evil with matter, and this question is not 
entirely clear from the comp or lobian discussion.
We will not answer all this today, for sure.

Bruno




http://iridia.ulb.ac.be/~marchal/


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Re: why can't we erase information?

2006-05-04 Thread John M

Russell,
thanks for your fime and effort to reply. 3 things:

1. You picked my Hawkng typo, I have many more. I do
recall that post and it gives me while writing, the
subconscious vacillation: which version is the right
and which the left? Very rarely do I wright his name.

2. You use usable (used) physics views in a topic way
away from classical physics views, puting a systems
talk into space-time measuring with a morphology I
cannot (don't want to) follow in this thread. 

3. In your last par you said it: isolated from the
rest of the unkiverse exactly the singularity I DO
identify with Tom's description of a closed system. 

And 2Qs: 
Yours:
 What is an unknowable closed system?
If nothing (including information) comes out it must
be pretty unknowable. In that ballgame ou suppose:
it turns open from c;osed and then again closed,
I assume it disappears from our observation. I see no
indication that it keeps the same coordinates when
dissappeared as we found kit at when it was open.
The coordunates you want to find it at dissipate as
well.
Not to mention the changes or world ujndergoes to...
Mine:
RSt: Usually because it doesn't move :) Consider
 something inside a shielded container in a
vacuum...
How is move identified in connection with (my
version of) closed system (singularity) with no
interconnection in space lor time of OUR habiturl
system? Assigning coordinates to no-info sounds
funny. And the shielded vacuum container is Physics
101. 

 I am on a different track...

Regards

John M

--- Russell Standish [EMAIL PROTECTED] wrote:

 
 On Tue, May 02, 2006 at 01:33:37PM -0700, John M
 wrote:
  
  Russell, you 'opem' and 'close' a system? Why
 woulod
  you close it, once it is already open? and how
 would
  you find it again, when it is closed?
 
 Usually because it doesn't move :) Consider
 something inside a
 shielded container in a vacuum - many physics
 experiments are like
 this.
 
 Closedness, of course is an idealisation of the real
 system.
 
  
  And how do you assess those closed system laws,
 if
  no info goes in or out? (need an intelligent
 design?)
  
 
 As I said - by measuring the system at two points,
 in between which
 the system is closed. How the system evolves between
 those points in
 time will be closed system evolution.
 
  Is OUR time-scale valid to the inside of an
 unknowable
  closed system? You decide as you need - see below,
 
 What is an unknowable closed system?
 
  
  I segregated the black-hole type phantasms which
 allow
  action INTO them - and Hawkins had to make
 allowance
 
 Caution - misspelling Stephen Hawkings' name is
 considered a sure sign
 of a crank (I can't seem to lay my hands on the ref
 here...)
 
  even for them to 'release' SOME information as I
  understand. Well, these things are our
 brainchildren,
  not 'ntaure's' so we identify them as we need it.
  
  John M 
  
 
 Are you saying black holes are meant to be closed
 systems? I would
 have thought otherwise, unless it is isolated from
 the rest of the
 universe in some way.
 
 -- 


 A/Prof Russell Standish  Phone 8308
 3119 (mobile)
 Mathematics  0425
 253119 ()
 UNSW SYDNEY 2052  
 [EMAIL PROTECTED] 
 Australia   
 http://parallel.hpc.unsw.edu.au/rks
 International prefix  +612, Interstate
 prefix 02


 

 
 


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