1 "#DEEPAK MOHAN#" Schrodinger's Cat Paradox?? Mon, 28 Apr 2003 11:06:18 2 Richard Re: Schrodinger's Cat Paradox?? Sun, 27 Apr 2003 22:52:59 3 Uncle Al Re: Schrodinger's Cat Paradox?? Mon, 28 Apr 2003 07:53:09 4 "Dirk Van de moortel" Re: Schrodinger's Cat Paradox?? Mon, 28 Apr 2003 18:01:39 5 "Nicolaas Vroom" Re: Schrodinger's Cat Paradox?? Fri, 02 May 2003 18:40:55

Van: "#DEEPAK MOHAN#"
Datum: Mon, 28 Apr 2003 11:06:18

Hi, Can anyone put in simple terms what the "paradox" in Schrödingers cat Paradox is.

The Schrödingers cat consists of a cat in a box. The Schrödingers cat paradox is based around two events and a state. The first event is a random event. This is the release of a poisonous gas by a radioactive particle, which will kill the cat. The second event is an observer who will look inside the box. The state considered is the state of the cat: live or dead. The paradox is: the cat is only in a particular state after "you" have opened the box and looked inside. Before that moment the cat is not in one or the other state.

A paradox is "An assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises". This is a dictionary definition from somewhere.
In this case, Schrödingers cat", I cant understand what the paradox is. If anyone knows anything please giv me some feedback? thanks d

Van: Richard
Datum: Sun, 27 Apr 2003 22:52:59

#DEEPAK MOHAN# wrote:
 > Hi, Can anyone put in simple terms what the "paradox" in Schrödingers cat Paradox is. The Schrödingers cat consists of a cat in a box. The Schrödingers cat paradox is based around two events and a state. The first event is a random event. This is the release of a poisonous gas by a radioactive particle, which will kill the cat. The second event is an observer who will look inside the box. The state considered is the state of the cat: live or dead. The paradox is: the cat is only in a particular state after "you" have opened the box and looked inside. Before that moment the cat is not in one or the other state. A paradox is "An assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises". This is a dictionary definition from somewhere. In this case, Schrödingers cat", I cant understand what the paradox is. If anyone knows anything please giv me some feedback? thanks d

This paradox was presented as a thought experiment designed to show that states are independent of the act of observation, i.e. it is obviously absurd to think that the state of the cat is not already determined before observation of it. There were those at the time of the conception of this experiment that were swearing stupidly that reality was observer created. Perhaps he would have made more of an impact if he had reported that school to the mental health authorities. They were obviously completely detached from reality and thus were a danger to themselves and others. Just imagine one of these guys veering into your lane thinking "if I keep my eyes closed neither I nor they will be dead until I open them." If OTOH he died in the crash, thus never able to observe the outcome, then your state would suspended in eternal flux:)

--

Richard Perry http://www.cswnet.com/~rper

Van: Uncle Al
Datum: Mon, 28 Apr 2003 07:53:09

#DEEPAK MOHAN# wrote:
 > Hi, Can anyone put in simple terms what the "paradox" in Schrödingers cat Paradox is.
[snip]

A superposition of quantum states doe not collapse into an observable until you look. "It ain't a strike or a ball 'til the ump makes a call." There is no fundamental truth; physical reality is not pre-determined.

 > A paradox is "An assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises". This is a dictionary definition from somewhere. In this case, Schrödingers cat", I cant understand what the paradox is. If anyone knows anything please giv me some feedback?

The paradox is that the cat is simultaneously alive and dead (a superposition of states weighed by their probabilties). The macroscopic example is obviously defective, but it serves to illustrate the point. Microscopic examples abound, and they play by Shroedinger's rules.

Example: If you have an atomic transition decay that proceeds through a forbidden virtual state and you optically saturate "the state that is not there," the excited state becomes indefinitely stable. As long as you "look" it can't sneak through riding a footnote.

-- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) "Quis custodiet ipsos custodes?" The Net!

Van: "Dirk Van de moortel"
Datum: Mon, 28 Apr 2003 18:01:39

"#DEEPAK MOHAN#" wrote in message news:7E6B0136648F5648A644FFE4CA90424C205CD6@exchnews2.main.ntu.edu.sg...

 > Hi, Can anyone put in simple terms what the "paradox" in Schrödingers cat Paradox is. The Schrödingers cat consists of a cat in a box. The Schrödingers cat paradox is based around two events and a state. The first event is a random event. This is the release of a poisonous gas by a radioactive particle, which will kill the cat. The second event is an observer who will look inside the box. The state considered is the state of the cat: live or dead. The paradox is: the cat is only in a particular state after "you" have opened the box and looked inside. Before that moment the cat is not in one or the other state. A paradox is "An assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises". This is a dictionary definition from somewhere. In this case, Schrödingers cat", I cant understand what the paradox is. If anyone knows anything please giv me some feedback? thanks d

The cat is alive or dead. We don't know until we look. When we look, we know whether the cat is alive or dead. [ If the cat is smart enough, it knows that it is alive as long as it is alive ;-) ]
The "wave function" and "state" are merely mathematical constructs that we can use to *describe* our uncertainty of the situation and - in more complicated, less trivial cases - to calculate probabilities of outcomes of experiments. Before we look, all we can do is use a wave function that tells us that the two outcomes each have a 50% probability. When we have looked, we can write another, rather trivial wave function that tells us that the probability of whatever we found, is 100%.
This is sometimes called the "collapse of the wave function", an i.m.o. rather silly expression.

By the way, according to www.webster.com, a paradox is merely a *seemingly* contradictory statement.

Dirk Vdm

Van: "Nicolaas Vroom"
Datum: Fri, 02 May 2003 18:40:55

"#DEEPAK MOHAN#" schreef in bericht news:7E6B0136648F5648A644FFE4CA90424C205CD6@exchnews2.main.ntu.edu.sg...

 > Can anyone put in simple terms what the "paradox" in Schrödingers cat Paradox is. The Schrödingers cat paradox is based around two events and a state. The first event is a random event. This is the release of a poisonous gas by a radioactive particle, which will kill the cat. The second event is an observer who will look inside the box. The state considered is the state of the cat: live or dead. The paradox is: the cat is only in a particular state after "you" have opened the box and looked inside. Before that moment the cat is not in one or the other state.

Science has all to do with experiments, many experiments.

Start with a piece of radioactive material and call this state0 With a Geiger Muller Counter and a StopWatch you write down the time when the first particle is emitted. This is state1 You do the same with the second particle. This is state2 Finally with the n'th particle. Now you are in state n. What you are left with is a sheet with the time of n events.

You can repeat the same experiment. The result will be a second sheet with the time of n events.

Those two sheets should be approximate the same. That means the total time of n events should be the same.

But it is not always the case. Suppose you start point is a piece of Uranium or Element 92. The interesting aspect of Uranium is that it comes in two types or isotopes: Uranium 235 and Uranium 238. (U235 and U238) U235 is stable and only U238 is radioactive.

Generally speaking if you have two "identical" pieces of Uranium but the second one contains twice as much U238 than the second piece will transmit twice as much particles.

If you know that you can make identical pieces of Uranium which contain the same percantage of Uranium and when you repeat the above experiment you will see that the final time on each sheet after n events will be identical within a certain spread.

Now you can also test under other different conditions. You can perform the experiment with or without an Observer close to the experiment. The time of the n events will be identical. That means that if there is an Observer available has no influence on the experiment i.e. radioactive decay.

You can also repeat the experiments but now with or without a cat. Again the result will be that cats have no influence.

In the above example I have called the initial state of the piece state0 and the state after the detection of the first particle state1 In the Schrödinger Cat experiment those two states are equivalent with: the cat is alive and the cat is dead.

In the Schrödinger Cat experiment there is also something else this is called a superposition of both the cat is alive and the cat is dead. This is the state in which the cat is before you have looked in side the box.

Suppose I perform the whole experiment including the Geiger Muller Counter is in a closed laboratory and I run the experiment for the same average period as the n events. I open the laboratory and I look on the Geiger Muller Counter and I read n. Does that mean that before I looked the GMC was in a superposition of state0, state1, state2 until state n ?

Ofcourse I can say that but what does it (physical) mean?

There are two things that I know First I know that when I read value n on my GMC that the piece of radioactive Uranium has emitted n particles. Secondly I know that, after the average time of n events, the longer time I wait with reading my GMC, the higher is the chance that I will read the value n or higher on my GMC. In the Schrödinger Cat experiment this is equivalent with that the cat is dead.

That is all what I know. No more. No less

A follow up problem is if you can use the concept of superposition in order to build or explain the functioning of a certain device.

For example can you use the concept of superposition in order to explain the functioning of a Quantum Computer.

In above discussion I have used the radioactive element Uranium in order to discuss and explain (?) the concept of superposition.

So my first question is are the basic building of Quantum Computer (the Qubits) built with radio active elements.

How do you built then Quantum Registers consisting of two Qubits ? The problem is if you built a Register of two Qubits using a radio active element the initial state will be 00 (No particle emitted) than 10 or 01 (One particle emitted) and finally 11 (Both qubits have a paricle emitted)

The problem is you can not go back. Go back to state 00.

In the schrodinger cat environment the state 00 is equivalent with both cats alive and the state 11 is equivalent with both cats dead.

IMO it is very difficult to make a Quantum Computer where the Qubits are made from radio active elements.

Suppose the answer is No. i.e. the Qubits do not use radioactivity.

If you did not use a radioactive element what is than what did you use and what is the definition of superposition ?

In electronics you have what are called oscillators. An oscillator switches continuous between a state of zero and one but an oscillator is either in the state 0 or state 1 but never in both. You can make a register out of two oscillators and you can give each oscillator a different frequency. Your register goes than continuous through the 4 states:

00, 01, 11, 10, 00, 01, 11, 10 and 00 etc etc.
Each time your register is always in a particular state and there is no superposition involved.

You can use electronics to built a Computer but you can not use such a Computer a Quantum Computer if the definition of what is a QC is not clear. For example: that a QC should incorporate superposition when what you mean by superposition is not clear.

My point is that you can only learn by performing experiments and not by performing thought experiments. Secondly if you use certain terminology in order to explain something then it must be clear what you mean. To claim that a piece of uranium before it has emitted 3 particles is already in a superposition state of those three particles is "nice" but explains nothing. Also concepts like collapse of a wave function, describing what happens when you perform a measurement, are not clear and or explain nothing.

My prediction is that the importance of Schrödinger Cat Paradox will diminish in due time.

Created: 26 September 2001