So is the cat dead or alive?

Factual Questions
41

Try In Search of Schrodinger’s Cat : Quantum Physics and Reality by John Gribbin. It’s an easy read, and he goes into the two-slit and cat-in-box experiments extensively. Then you can move on to the update, Schrodinger’s Kittens and the Search for Reality : Solving the Quantum Mysteries. I found my copy in the pet section of the bookstore, by the way. ::sigh::

“Happiness is nonetheless true happiness because it must come to an end, nor do thought and love lose their value because they are not everlasting.”

  • Bertrand Russell
42

People who take the cat paradox literally may as well take Noah and the Ark literally. They’re just stories told to make a point. I don’t think Schroedinger expected anyone to actually conduct such an experiment.

Those who do not learn from the past are condemned to relive it. Georges Santayana

43

Um, jab? Duh.

I’ll check out the books; thanks, guys.

44

Sorry.

What if you used an anesthetic gas instead of a poisonous one? Would the cat then be both awake and asleep?

Those who do not learn from the past are condemned to relive it. Georges Santayana

45

I think Jodih has a point. Why isn’t the answer neither dead nor alive? Cooper said the ‘observer’ didn’t have to be human, therefore the trigger is the observer because it is the point of interaction with the macro world. To trigger the gas it has to be in that specific state and the cat dies whether we know it or not. So to get to a point before the observation is made by the trigger mechanism, then actually the cat is alive, potentionally dead. Did that make sense?

46

Ok, you asked for it, more pop explanation.

We’ve established that:

  1. At the quantum level, a particle exists in all possible states (of position and momentum) which have varying degrees of probability.

  2. At the macro level, an object has a definite position and momentum.
    Question #1: How do we know that a quantum particle exists in all these simultaneous probability states?

Answer: The double slit experiment. When one and only one photon is released near a double slit and measured on the other side, it lands in an interference pattern suggesting that it went through both slits simultaneously. It interacted with itself (that is, a group of high probability states {going through slit A} interfered with another group of high probability states {going through slit B}).

So, to answer to the related question of:

Question #2: "Didn’t the particle have a definite position and momentum right before we measured it?"

Answer: No. When left to itself (without direct measurement) the particle follows quantum mechanics’ laws of probability states.

Now, here comes the real mind bender:

I’ve been talking about the probability wave collapsing once we measure a particle. That’s not entirely true. We never get a definite fix on a particle’s position and momentum. If we were to measure a particle that had a definite position, its momentum would be completely (and I mean completely) unknown.

And likewise, if we ever measured a particle’s definite momentum, it’s position would be completely unknown.

Sometimes we can measure a particle’s general position and momentum, but never, never, never, get a definite fix on both. This is as an inviolable rule (Heisenburg’s, actually) as is Einstein’s rule about the speed of light.

So, now, question #3: "So how can this quantum world of probability give rise to the macro world of definiteness?"

Answer: Flip a coin a billion, billion times, and you’re going to get so close to a 50-50 chance of heads or tails, that you might as well say that it definitely will be 50-50.

Sure, one of the electrons attached to the nucleus of a hydrogen atom within a water molecule in my eye may make a sudden quantum jump to the center of the moon, but the chances are so slim, that it just doesn’t happen.

The probabilities favor a very narrow and very predictable way of behaving. Sure, if you’re the size of an electron, the ‘probability cloud’ of an electron in an atom seems huge. And it would seem very non-Newtonian to ‘see’ the electron hop around that cloud blinking in and out of ‘sight’ (yeah, yeah, observing it forces position), but when you’re the size of us, that electron is like a solid ball. And when we observe it, we ‘see’ it as a point frozen in time in a particular place in orbit, though its probility wave causes it to exist as a cloudy shell.

Quantum mechanics is ordinarily ignored in everyday life. We pay attention to it when we have to deal with individual particles – as with one partical going through double slits; or quantum tunneling.

Peace.

47

For the record (Cecil, are you listening?) the Schroedinger’s cat column is my favorite EVER.
“No grease monkey I, but a Quantum Mechanic!”

It goes right up there with Stanislaw Lem’s epic poem “Love and Tensor Algebra”
(“Elipse of Bliss, converge, O lips divine/
the product of our scalars is defined”)

48

For those who are confirmed SF fans, Robert A. Heinlein wrote a book entitled The Cat Who Walked Through Walls that was a rather clever ploy on the Schrodinger’s Cat paradox, including characters who were (for reasons logical within the story) infuriated with 20th Century theoretical physicists. The title character, a orange kitten named Pixel, incidentally could do precisely as the title implies, apparently through controlled quantum tunneling. (SF is allowed one not-in-the-real-world postulate, as long as it stays logical within that postulate.)

49

Aw, fuck it. Just tell me how many angels can dance on the head of a pin.

LONESOME POLECAT

+++++++++++++
When the pin is pulled,
Mr. Grenade is no longer
our friend.

50

Polecat

Depends. If the angels are pair coupled, the probability is collapsed in only a binary quantum state. However, if they are line dancing, you can get as many as you want. Don’t even ask about mosh pits.

<p align=“center”>Tris</p>