On 09-Sep-02, Bruno Marchal wrote:
> Jesse Mazer wrote:
>> Bruno Marchal wrote:
>> Jesse Mazer wrote
>> Ok, I think I see where my mistake was. I was thinking
>> that "decoherence" just referred to interactions between a
>> system and the external environment, but what you seem to
>>
Jesse Mazer wrote:
>Bruno Marchal wrote:
>
>>
>>
>>
>>Jesse Mazer wrote
>>
>>
>>
>>>
>>>Ok, I think I see where my mistake was. I was thinking that
>>>"decoherence" just referred to interactions between a system and
>>>the external environment, but what you seem to be saying is that
>>>it
Bruno Marchal wrote:
>
>
>
>Jesse Mazer wrote
>
>
>
>
>>
>>Ok, I think I see where my mistake was. I was thinking that "decoherence"
>>just referred to interactions between a system and the external
>>environment, but what you seem to be saying is that it can also refer to
>>an internal effect
Jesse Mazer wrote
>
>Ok, I think I see where my mistake was. I was thinking that
>"decoherence" just referred to interactions between a system and the
>external environment, but what you seem to be saying is that it can
>also refer to an internal effect where interactions among the
>comp
Brent Meeker wrote:
>OK, consider a single excited hydrogen atom in a perfectly
>reflecting box. Has it emitted a photon or not? QM will
>predict a superposition of photon+H and H-excited in which
>the amplitude for H-excited decays exponentially with time.
> But the exponential decay is only a
J. Mazer:
> But can decoherence really "forbid" macroscopic superpositions in principle,
> or only in practice?
Well, experiments have been done many times, showing
the effect of decoherence on (macroscopic) quantum superpositions
http://physicsweb.org/article/world/13/8/3/1
http://physicsweb.org
J. Mazer [about Wigner and consciousness]
> Did Wigner only believe this until his change of opinion in 1983, or did he
> continue to think this way afterwards?
Wigner wrote (Nov. 18, 1978) ...
" ... as far as living organism of any complexity are concerned, the same
initial state hardly can b
Jesse Mazer wrote:
> But can decoherence really "forbid" macroscopic superpositions in principle,
> or only in practice? To build quantum computers, people have to figure out
> clever tricks to keep fairly large systems in quantum coherence, even though
> under normal circumstances decoherence
scerir wrote:
>Wigner later (1983) changed opinion and wrote
>that decoherence forbids superposition of states like
> c1 |s 1> |friend 1> + c2 |s 2> |friend 2>
>After that in QM the "conscious" being - i.e. the "friend"
>who tells that he already "knows" whether the outcome is
>|s 1> or |s
> Yes, this is similar to the "Wigner's friend" thought-experiment.
Wigner later (1983) changed opinion and wrote
that decoherence forbids superposition of states like
c1 |s 1> |friend 1> + c2 |s 2> |friend 2>
After that in QM the "conscious" being - i.e. the "friend"
who tells th
Brent Meeker wrote:
>On 04-Sep-02, Tim May wrote:
>
> > By the way, issues of observers and measurements are
> > obviously fraught with "Chinese boxes" types of problems.
> > In the Schrodinger's Cat pedantic example, if the "cat
> > alive or cat dead" measurement is made at the end of one
> > ho
On 04-Sep-02, Tim May wrote:
> On Wednesday, September 4, 2002, at 02:44 PM, Hal Finney
> wrote:
>> Tim May wrote:
>> In weaker forms of the MWI, where it's the early state
>> of the Big Bang (for example) which are splitting off
>> into N universes, De Witt and others have speculated (as
>> ea
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