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Sitaram · Site Admin Joined: 14 Sep 2005 Posts: 1079

Date: Sat Sep 20, 2003 6:03 pm
Subject: Schroedinger's Cat: Wanted, Dead AND Alive om_namah_shi...

http://sulekha.com/chpost.asp?for...ilosophy&show=0&cid=72743

I am fascinated by topics regarding Schroedinger's cat and quantum.

But when I quickly read your post, off the top of my head, I suspect
that you possibly mistated the problem.

As I remeber, there is a certain quantum phenomenon which somehow
only takes place (or is decided) AT THE MOMENT THAT THE OBSERVERS
CHOOSES TO OBSERVE the results of the experiment.

Shroedinger posits a situation in which the resulting state of the
quantum phenomenon could causally effect the opening of the cyanide
capsule, and result in the cat's death.

HE THEN went on to state that the cat would not die UNTIL the moment
that the observer observes.

Now I know that this is extremely hard to fathom, and I do not
pretend to have ever understood it precisely. It may be involved
with Bell's theorem, but I must now go and consult google.com.

I do distincly remember that it was not a simple matter of whether
the capsule might break as we toss it in the box and close the lid.
The entire point of the cat metaphor was to illustrate an odd
situation in which the cat is NEITHER ALIVE NOR DEAD (or rather is BOTH ALIVE
AND DEAD) until the moment that the observer observes.

My apologies to all, if my poor old memory has failed me on this
matter.

And now, off to google.com to see what this cat is really all about!

- Sitaram

====

http://www.emr.hibu.no/lars/eng/cat/Default.htm

One can even set up quite ridiculous cases. A cat is penned up in a
steel chamber, along with the following device (which must be secured
against direct interference by the cat): in a Geiger counter there is
a tiny bit of radioactive substance, so small, that perhaps in the
course of the hour one of the atoms decays, but also, with equal
probability, perhaps none; if it happens, the counter tube discharges
and through a relay releases a hammer which shatters a small flask of
hydrocyanic acid. If one has left this entire system to itself for an
hour, one would say that the cat still lives if meanwhile no atom has
decayed. The psi-function of the entire system would express this by
having in it the living and dead cat (pardon the expression) mixed or
smeared out in equal parts.

http://www.telp.com/philosophy/qw2.htm

Schroedinger's Cat

The Role of the Observer

Measurement operations on a quantum system always give some definite
answer, informing us that the system is in one of the definite states
detectable by the measuring device. For example, an exposed grain of
photographic film testifies that the electron was there and no where
else when it deposited its energy in the detector. All subsequent
observations will be consistent with the first. So, for example, if
an electron is actually observed traversing slit 1, any future
observations made on it will show it behaving as a small pellet that
has gone through that slit, not as part of a superposition of slit-1
and slit-2 waves. The measurement observation changes the state of
the system, replacing a superposition with a definite state.

What is it about the act of observation that causes such a change?
Quantum systems are microscopic, simple, and have only small amounts
of energy. Energy must be transferred to the measuring device if the
quantum is to be detected at all, and that energy will be a
significant amount of the total available, so it is obvious that
measurement will be disruptive. But how is it that superpositions
never survive an act of measurement? And what kind of interaction
does it take to remove a superposition and put a quantum system in a
definite state? Many attempts to probe these questions have centered
around Erwin Schroedinger's famous thought experiment involving a cat
in a box.

So What's the Problem?

It might seem as if the process of decoherence can dispel these
questions of the role of the observer in quantum mechanics.
Decoherence through amplification is, after all, a purely physical
process. No consciousness is required to make it happen. Our choice
to look in the box has no effect on the subsequent behavior of the
system; it only effects our state of knowledge about it.

In the Copenhagen Interpretation, all unobserved states
(superpositions and mixtures both) are viewed very much alike from a
philosophical standpoint. Because no observation has yet been made on
them, they are not considered objectively real (since objectivity
implies that different persons have a shared experience of the
phenomenon, and before observation there is no experience to share!).
Some of these unobserved states (the coherent ones) have interference
terms in their descriptions, others do not. Either way, our
description incorporates the incompleteness of our knowledge--
knowledge that can only become complete through actual observation.
With this philosophical orientation, one would indeed say that the
cat is neither alive nor dead as a matter of objective reality until
an observation is made.

From a philosophical orientation that is more metaphysical and less
epistemological, there is no great difference between a pre-
observation mixture and a post-observation single state. From this
perspective, the objective reality of the cat's condition does not
change on opening the box. If the cat is objectively dead, it became
so the instant the flask broke, not at some later time when the box
was opened. These two philosophical viewpoints are equally consistent
with the facts; there is no experiment that can distinguish between
them. It is more a matter of preference than of science.

The transition from superposition to mixture, and hence the
transition for quantum weirdness to classical normalness, can indeed
happen long before any human observes the system. In fact, it usually
does. But this fact alone is not enough to completely separate the
process of conscious observation from the behavior of quantum
systems. Although we can have mixtures without observation, we still
cannot have superpositions with observation. We can only directly
observe states that are no longer in superposition. The coherence can
be lost long before the observation, or it can be lost at the moment
of observation, but it cannot be lost after the observation. Whenever
we look we see something--something definite, the system in a well-
defined state. In classical physics, we are free to assume that the
system was in that state all along, before we bothered to look. In
quantum mechanics, this assumption is sometimes possible (if we are
observing a mixture), but soemtimes not (if we are observing a state
that was in superposition).

Observation on a mixture state has no physical consequences, and so
we are free to endulge either an epistemological or a metaphysical
view of reality when it comes to mixtures; it makes no difference.
But if you follow the metaphysical perspective, you enter a nightmare
world when you try to extend your picture of reality to encompass the
superposition states too. A dead cat and a live cat do not interfere
with each other, but an electron going through slit 1 and an electron
going through slit 2 do. Accounting for the interference and
maintaing a picture of a single, localized, objectively real electron
traversing the experimental apparatus is impossible. It is this
impossibility that is demonstrated and put into experimentally
testable terms by Bell's inequality.

In no case, however, should one think of consciousness as physically
producing a change in the state of a system, either forcing a
superposition into a mixture or forcing a mixture into a single
state. Observing the cat does not kill the cat. It is very
unfortunate that many popular writers on quantum mechanics have given
this impression of the role of the observer. It is inconsistent with
both the epistemological philosophy of the Copenhagen Interpretation
and the metaphysical philosophy of hidden-variable approaches such as
Bohm's.

http://www.telp.com/philosophy/qw3.htm

http://www.phobe.com/s_cat/s_cat.html

http://www.sciam.com/article.cfm?articleID=000AAB4F-7BC2-1C76-
9B81809EC588EF21

Schroedinger devised the cat experiment to illustrate just how
radically the quantum realm differs from the macroscopic, everyday
world that we inhabit. He himself had shown that a particle such as
an electron exists in a number of possible states, the probability of
each of which is incorporated into an equation known as the wave
function. In the case of an atom of radioactive material, for
example, the atom has a certain probability of decaying over a given
period of time.

Based on our "classical" intuition, we would assume that there are
only two possibilities: either the atom has decayed, or it has not.
According to quantum physics, however, the atom inhabits both states
simultaneously. It is only when an observer actually tries to
determine the state of the atom by measuring it that the wave
function "collapses," and the atom assumes just one of its possible
states: decayed or undecayed.

Schroedinger reasoned that such probabilistic behavior could exist in
the macroscopic world as well, even if we are rarely aware of it. He
imagined a box containing an atom having a 50 percent likelihood of
decaying in an hour, a radiation detector, a flask containing poison
gas and a cat. When or if the atom decays, the Geiger counter will
trigger a switch that causes a hammer to smash the flask, releasing
the gas and killing the cat. When the experimenter opens the lid of
the box and peers inside after an hour has passed, he or she will
find the atom either intact or decayed and the cat either alive or
dead. But according to quantum mechanics, during the period before
the lid is opened, the cat exists in two superposed states: both dead
and alive.

During the 1980s, the late theorist John Bell suggested a more
palatable version of Schroedinger's experiment, one in which the
decay of the atom causes a bottle of milk to spill onto the floor;
the superposed cat is thus hungry or full rather than alive or dead.
But either version seems weirdly nonsensical: the outcome seems
logical from a quantum physics viewpoint, but common sense tells us
that a cat cannot be alive and dead (or hungry and full) at the same
time.

The paradox of Schroedinger's cat has provoked a great deal of debate
among theoretical physicists and philosophers. Although some thinkers
have argued that the cat actually does exist in two superposed
states, most contend that superposition only occurs when a quantum
system is isolated from the rest of its environment. Various
explanations have been advanced to account for this paradox--
including the idea that the cat, or simply the animal's physical
environment, can act as an observer.

The question is, at what point, or scale, do the probabilistic rules
of the quantum realm give way to the deterministic laws that govern
the macroscopic world? This question has been brought into vivid
relief by the recent work done by the NIST team, which includes
Christopher Monroe, Dawn Meekhof, Brian King and Dave Wineland. The
group confined a charged beryllium atom in a tiny electromagnetic
cage and then cooled it with a laser to its lowest energy state. In
this state the position of the atom and its "spin" (a quantum
property that is only metaphorically analogous to spin in the
ordinary sense) could be ascertained to within a very high degree of
accuracy, limited by Heisenberg's uncertainty principle.

http://www.ravenblack.net/thoughts/multiverse.html

I find Multiverse theory to be aesthetically pleasing as well as
quite compatible with many other disputed theories. My particular
favourite flavour of Multiverse is also fun for its sheer
ungraspability. Everything that could possibly happen does, each
branching into a new universe (or a new 'verse', I suppose). Each
infinitesimal fraction of a second, there's near enough an infinite
number of possible things that could happen (which way is that
electron going to vibrate?). Picture a multiverse branching so many
times. Not easy.

The thing I like most about such a system is that both
predetermination and free will are fully functional. The whole
incomprehensible infinite-squared thing (mathematicians say that
there's a difference between infinity and infinity-squared) is
predetermined. Nothing you do can make another possibility possible.
But which 'verse' your consciousness follows is free will.

This works with Quantum Mechanics and the 'everything affects
everything else' theory. For Quantum Mechanics I shall use the old
favourite, much misquoted, and entirely unserious Schroedinger's Cat
example, which states approximately:

"Shut a cat in a box with a poison capsule which has a fifty percent
chance of releasing its poison (using the decay of a radioactive
isotope for the 'random' factor). The cat enters a quantum state in
which it is 'both alive and dead'. When the box is opened and the cat
observed, the state collapses into one of the two possibilities."

Attaching that to my Multiverse theory, the cat is always both alive
and dead. The opening of the box is the point at which it is decided
which of the 'verses' your perception has followed. Whether you've
followed a branch before the box is opened is debatable, much in the
same way as Schroedinger's example is often debated.

This multiverse, then, is already mind-bogglingly huge (and some
people have trouble with the concept of the size of a mere universe).
Think, then, consider that time since 'The Big Bang' mightn't be the
start of the multiverse, but merely a branch, relatively tiny given
that there's a similar sized branch a fraction of a second earlier,
one later, ad infinitum.

Does magic work in the multiverse? Are horoscopes true? Of course.
Also no. If your perception decides to follow one of the routes
described by your horoscope then it's (to you) true. Perhaps your
perception might decide to follow a route where your horoscope is
true for a whole twelfth of the population. The same goes for magic.
You perform some psychic act and bend a spoon. Well done, you've
entered a 'verse' where the spoon bends. All the sceptics watching
probably took a different branch (at least those consciousnesses
which wanted to carry on not believing).

In terms of dimensions, this huge hypothetical thing requires only
five. The three we perceive ordinarily, time (which some consider to
be a fourth already, some argue otherwise), and a fifth, 'branch'. Of
course, branching might work in more than one dimension, much as
movement.

Time travel is also quite compatible with the multiverse. Going back
twenty minutes, you bump into yourself. It's one of you who followed
a branch in which they meet themselves coming back in time. You might
or might not have met yourself at that time, depends which branch you
were in. Then you can 'change the future', except you don't, you
merely take a peek at a different one. You kill your father,
depriving a branch of yourself (except, of course, it was already
without yourself, because you do go back in time and kill your
father, somebranch).

The Nature of Time

http://www.ravenblack.net/thoughts/time.html

The speed of light... Much of the science based around the speed of
light is thanks to Einstein. e=mc2, for example, energy is equal to
mass times the square of the speed of light in a vacuum (c stands
for 'constant', here).

An interesting point about that - if 'c' is a constant, 'c2' is also
a constant. So the equation would be less misleading if it
read "e=mc". After much thought on the subject, I consider that it is
for clarity that the number is squared.

Presumably there has been some derivation through what are accepted
to be the three measures, distance, time and mass. Speed being
distance/time, that would mean energy is measured in (mass *
(distance/time)2), which would be kgm2s-2. (kilogram metres squared
per second squared). I don't know if that's what a Joule is, and
don't feel like looking it up. If it's not then there's something
even more dodgy in Physics than I thought.

On to the next dodgy point, relativity. Time is relative, says
Einstein. Motion is relative, says Newton. Both are accepted as fact.

Time being relative to motion is Einstein's point; as one approaches
the speed of light, time slows down. If one could exceed the speed of
light (which it is usually assumed one can't) they would go backwards
in time. The catch is, apparently, that if one were to travel at the
speed of light away from Earth for a light year, then back again, the
time on your watch would match the time on Earth because your travel
has been accelerated out and decelerated in (or some such). However
(this bit makes no sense to me), it is also said that if one flew in
a circle at the speed of light, the clock you have would not match
the stationary clock on Earth, but be a short time behind.

Accepting this as fact, for no good reason but argument, I then go on
to apply Newton. Motion is relative. So, as far as the moving clock
is concerned, it was the other clock that was moving. So it's the
other clock that's a short time behind.

So, what's going on here? Clock A looks at clock B and says "You're
two seconds behind, mate."

Clock B looks at clock A and says "Nonsense, you're the one that's
two seconds behind."
I think not.

People have suggested to me that it's because of acceleration. This
doesn't help at all - acceleration being a motion/time comparison,
and motion being relative, clock A says clock B is accelerating, and
vice versa, just as with moving.

How to explain this discrepancy? I have two ideas. Reject the time is
relative proposal (which at face value looks to be the less likely),
or reject the motion is relative proposal. If one were to do the
latter, then motion needs something to be compared against. A
control, as it were.

The argument in favour of this is that if one were to reject relative
time, travelling faster than the speed of light would be possible.
Consider in relative motion without time dilation, object A travels
west at two thirds of the speed of light, while object B travels east
likewise. Relative to each other they would be travelling at one-and-
a-half times the speed of light.

How about if it were possible to travel faster than the speed of
light, and time dilation occurs, such that one goes back in time?
Paradox becomes the order of the day, what happens if I go back and
stop myself building the time machine? What happens if I go back and
stop myself being born? The whole idea of time travel is preposterous
unless there's some way to sort this out. Two ways spring to mind for
me. Multiple time lines, as explored vaguely in Back To The Future 2,
meaning that all you do is create or travel to a different branch of
the 'universe' , or linear fourth-dimensional predestination-filled
time, wherein you obviously can't go back and stop yourself being
born because you didn't. Whatever you might try won't work, and you
know this because it didn't work, because you were born. You can go
back and affect things, but you can't change things. Any changes you
make go to make the world the way it already is.

On to another tack, along the same lines. If time is a fourth
dimension, what amount of time is the equivalent of a metre? Picture
some primitive four-dimensional shapes... How about the pyrasphere, a
sphere that shrinks slowly into nothing. I think of this being to a
cone what a pyramid is to a square. Try to picture it with the fourth
dimension being something other than time. Just another form of
distance. If you can see that then you should be able to manage to
ponder a five-dimensional shape. Get the pyrasphere and shrink it.
About there it starts to get tricky to picture, for me. With a little
effort I can go as far as imagining a six-dimensional form without
using time.

If you managed the relatively simple task of imagining the pyrasphere
using time as your fourth dimension, try rotating it ninety degrees
through the dimensions. Time becomes up, up becomes right, right
becomes back and back becomes time. What does the pyrasphere look
like now? Tricky, isn't it? I may write a program to do such
tranformations, because I'd like to see a person moving the wrong way
through the dimensions.

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