On 15 Dec 2017, at 03:47, [email protected] wrote:
On Friday, December 15, 2017 at 2:27:46 AM UTC, Jason wrote:
On Thu, Dec 14, 2017 at 8:20 PM, <[email protected]> wrote:
On Thursday, December 14, 2017 at 2:54:01 PM UTC, Jason wrote:
The solution was proposed by Everett in 1957, collapse is a
subjective illusion. The dead cat and its history of decomposing
for the previous hour does not materialize out of nothing from the
mere act of looking at it.
No measurement is made of the cat, the Geiger counter, or the atom,
by anyone outside the isolated system of the box, so according to
the Copenhagen Interpretation the superposition does not collapse.
The cat is both alive and dead. That is, until someone opens the
door to peek inside. In that instant, the wave function collapses
and the system randomly “decides” whether the cat is alive or dead.
If the state collapses to that of the dead cat, what happens to the
experiences of the cat who was in the superposition of being alive
and dead over the past hour? Do they suddenly vanish as if they
never happened at all? Perhaps they never existed in the first
place, as Bohr’s anti-realist approach would answer. But this leads
to another problem: if the cat is observed to be alive, do all of
its memories and experiences over the past hour suddenly pop into
existence? Is the cat’s experience of 15 minutes ago ever experienced?
It is one thing to believe that microscopic particles might be in
two different states at once, but quite another to believe the same
for a large and complex system, such as a cat. The CI implies that a
living, breathing cat, with a consistent history and memories of the
previous hour, can instantly materialize from the simple act of
observation.
Schrödinger's experiment has also been extended to highlight other
problems. The mathematical physicist Eugene Wigner discussed a
thought experiment known as Wigner’s friend. In it, Wigner’s friend
is in a room that is sealed off from the rest of the world and in
that room is a box containing Schrödinger's cat. The friend opens
the box after an hour and notices whether or not the cat is alive.
Sometime later, Wigner opens the door to the room to check on his
friend. When does the wave function collapse, when the friend checks
on the cat, or when Wigner checks on his friend? If it is when the
friend checks on the cat, then the isolated system, unobserved by
Wigner, has already collapsed (in contradiction to the CI). Yet, if
it does not collapse for the friend checking on the cat, this is
another contradiction, for he has made an observation of a system in
a superposition. The CI seems to have difficulties handling multiple
observers. mea
I don't see how Wigner's friend presents a problem for Copenhagen.
According to the CI, the wf collapses when the system measured,
which is when the box is opened. What am I missing? The issue of the
cat's memory is a different matter, problematic IMO. AG
The problem is according to the CI, an isolated system evolves
according to the Shrodinger equation, and therefore does not
collapse. But it also says observation causes collapse. So when you
have a conscious observer who is himself part of an isolated system,
from the point of view of another conscious observer, which rule wins?
If the system isn't isolated, it cannot be in a superposition of
states. So including the observer as part of the system is self
defeating if one wants to do a quantum experiment. The existence of
an observer doesn't contradict isolation of the system if the
observer is an instrument recording the result. AG
What is the difference you make between an instrument recording the
result and an observer? Consciousness? But that is what "Wigner's
friend" shows difficult to admit, and besides, I thought we all agree
that it is better that QM is the same for conscious and non conscious
beings?
Later you might understand that there is no "universe" at all. Only
long histories making people relatively rare, yet with a local measure
of one, which can stabilize the mundane type of consciousness. We need
only to assume one universal machinery (and elementary arithmetic that
everyone know is already such a system).
Eventually "physics" is explained by the bio-psycho-theo-logy of the
universal machine, itself reducible in arithmetic (but not just on its
computable part).
Bruno
Jason
If one takes the stance that the first conscious entity to
experience the result of a measurement causes collapse, whether
isolated or not, this still leaves the problem of large macroscopic
systems with complex histories popping into existence through
observation. If we replace the cat with some unconscious device,
like a sensor that prints off a receipt with the result of whether
or not the poison was released, then a conscious observer opening
the box causes the instantaneous appearance of the print out, oddly,
with ink that has long-since dried. It has a consistent history
seemingly invented at once.
Einstein was most impressed with Schrödinger's paper, and in 1950
wrote Schrödinger a letter of praise, saying “You are the only
contemporary physicist, besides Laue, who sees that one cannot get
around the assumption of reality, if only one is honest. Most of
them simply do not see what sort of risky game they are playing with
reality—reality as something independent of what is experimentally
established. Their interpretation is, however, refuted most
elegantly by your system of radioactive atom + amplifier + charge of
gunpowder + cat in a box, in which the psi- function of the system
contains both the cat alive and blown to bits. Nobody really doubts
that the presence or absence of the cat is something independent of
the act of observation.”
Einstein never accepted the quantum mechanics as a complete theory.
To the end of his life he searched for a theory that better fit his
ideals of realism, causality and determinism. But the answer he
sought was there all along: in the equations of quantum mechanics.
Consciously or unconsciously, however, the answer was simply too
strange for anyone to consider, even for a moment. It was not until
1957, more than three decades after quantum mechanics was
formulated, that anyone was bold enough to point out the answer that
was staring everyone in the face. That person was Hugh Everett III.
Jason
On Tue, Dec 12, 2017 at 3:04 PM, <[email protected]> wrote:
Not every superposition of states implies interference. Connect the
dots. AG
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