Re: Understanding Schrodinger's cat.

On Jul 14, 2:55 pm, "Nicolaas Vroom" <nicolaas.vr...@xxxxxxxxxx>
wrote:
"Nicolaas Vroom" <nicolaas.vr...@xxxxxxxxxx> schreef in berichtnews:Spqii.1841$u77.95326@xxxxxxxxxxxxxxxxxxxxxxxx





"Igor" <thoov...@xxxxxxxxxx> schreef in bericht
news:1183398328.634913.103190@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jul 2, 12:20 pm, "Nicolaas Vroom" <nicolaas.vr...@xxxxxxxxxx>
wrote:

Why do you call this effect a superposition ?

Because that's how it is defined. According to the Copenhagen
interpretation, all possible solutions to the appropriate quantum wave
equations are in full linear combination, or superposition, until an
observation is made. Once an observation has been made, one
particular state is realized.

Suppose I shuffle a card deck,
I place them face down in front of you
and I point my finger to one of them
and I ask you is that card red or black
Before YOU look is that card also in
a superposition of states red vs black ?

The whole idea behind this remark is to
define the concept of superposition
i.e. to define in what type of processes
we can speak of superposition
en when not.
If there is always superposition in volved
then what is the value of such a concept.

For example IMO it does not make sense
to define the cat in a superposition of
state of both alive and dead before you look
in the box if you know that in the experiment
no poison (and no radio active decay) is involved.
That means the cat is always alive when you open the box.

The same if you put the cat in a box already filled
with poison.
That means the cat is always dead when you open the box.

For the card deck example I have the same problem.
What is the physical significance to define
superposition related to the state of cards in a card deck.

In Nature of 5 July 2007 there are three articles
related to quantum physics.

At page 24 we read:
"According to quantum theory a card parefectly balanced
on its edge will fall down in what is known as a superposition
- the card really is in two places at once.
If a gambler bets money on the quenn landing face up,
the gambler's own state changes to become a superposition
of two possible outcomes - winning or losing the bet."

This is based on Everett's theory. "
At page 23 we read:.
"The theory can be summed up by saying that the
schrodinger equation applies at all times; in other words,
that the wavefunction of the Universe never collapses."

I have great problems with all of this.
Accordingly to Everett's theory before you open the box
the cat is always in a superposition of states
of both dead and alive even if there is no poison
involved.

What is the physical significance of all of this ?

What wories me the most how can you use
such a vaque concept to build a Quantum Computer.

At page 24 the following pressing question is raised:
if everett's theory is science or philosophy.
IMO the question is more if it is science
with a big S or a small s.

Nicolaas Vroomhttp://users.pandora.be/nicvroom/- Hide quoted text -

- Show quoted text -

Particles are always in a superposition state, even if it is a trivial
one. For example, a given cat could be in a superpositon state c1 |
dead_function> + c2 |alive_function>, where
|dead_function> is an eigenfunction with eigenvalue "Dead", and
|alive_function> is an eigenfunction with eigenvalue "Alive", and
and c1^2 + c2^2 =1.

Maybe we could call the relevant operator the Life operator. Both |
dead_function> and }alive_function> are eigenfunctions of the Life
operator, but the superpositon state c1|dead_function> + c2|
alive_function> isn't.

The probability of finding the cat "Alive" is c1^2, and the
probability of finding the cat "Dead" is c2^2. One could set up the
experiment in such a way that either c1 or c2 is exactly zero. That
make the wavefunction of the cat somewhat trivially a superposition
state.

The importance of superposition is that the eigenfunctions of an
operator form a "Complete set", which means that form a complete basis
for ANY function. You can write any function as a linear combination
of these eignefunctions.

I hope that answers your question.

.

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