On the other hand, if the wave function doesn’t collapse at the slotted-barrier, so that it can go through both slits simultaneously (as inexplicably shown on most diagrams of the experiment,) it should also reflect from the surface area between the slits and thus continue in the reverse direction back toward the source. If this reflected wave is a probability wave as well and is a continuation of the original wave, if a rear barrier-detector exists at the source, and is located at less distance from the slits than the forward barrier-detector on the other side of the slits, will the first wave function collapse at the rear detector prevent any photons from being recorded on the forward detector?

Doug

WE should, still worry?

Here is an example regarding the position of a particle:

Traditional realistic viewpoint - Things are where they are regardless of any measurment or measuring device.

Copenhagen (standard) Interpretation of QM - Things are where we measure them to be.

Information Theoretic version of Reality - Things are where they “tell us” they are. QM effects are due to the fact that reality does not have infinite bandwidth to give us information about itself. If it did it would require infinite energy. So reality is bandwidth limited.

I could be wrong. But I don’t worry about it anymore

Elliot

AS a “observer” you need a place from which to do that? Is it really outside of the 3+1 that we know and love?

While one talks about a “decay process” you might be engaging in mathematical realms that seem very far away, yet are really under our nose? :)It’s a way of how we look at our surroundings?

It seems so easy in a visual sense, yet it has move to asbtract mathematical thinking? Would we say that these people who have these same questions in this thread have been removed from reality?

Dissident:”Knowing the probability of an event is not the same as knowing when or even that it will occur within a certain amount of time.” What does this mean?
1.If I measure a nucleus, the nucleus goes to either |decay> or |undecayed>.
2.”The probability that a nucleus would decay within 1 hour is 1/2.”
Does that mean these two are different? But the experiment uses nucleus…, with a detector waiting for emitted particle.

The reason that I want to replace an unstable nucleus with an excited atom is that: Physicists are more familiar with an atom emitting a photon. Right? At least to me:-)

If Schroedinger really wanted to entangle nucleus with a big cat, I guess detector must not be included. If there’s detector, what are entangled are a nucleus and a microscopic detector, not a cat. If he’d say “detector and cat are also entangled.”…

What if the state of the nucleus is this?:
|unstable nucleus> = |decay(ground)> + |not decayed1(first excited)> + |not decayed2(second excited)> +…
Then the situation becomes different, right? I hope I’m not starting to become nuisance.

Is the histories of the path taken, still intact? The screen becomes “something else” then would it not if given some new way in which to look at this??

E and B fields would be considered “real” and “existing” according to classical EM because they are objects of dynamical (Maxwell’s) equations. So, these fields are partially what the world is made of according to this theory. Doesn’t sound too bad.

Could we extend this viewpoint all the way back to classical mechanics? For example, suppose a particle is moving in one dimension (x-axis) under the influence of a known force. It’s trajectory x(t) would be an “object” that obeys a dynamical equation (Newton’s 2nd law). And so this function x(t) would “exist” and x(t) would be part of what the world is made of? x(t) would be just as “real” as the particle itself? I can use x(t) to predict where the particle will be a some instant of time - similar to using the wavefunction to determine the probability of finding the particle in a region of the x-axis at some time.

OK, I’m being a nuisance so I’ll quit. But I do find all of this interesting to ponder and thanks in advance for any further comments.

What if I use an electron with spin, instead of the unstable nucleus. And then measure spin up/down.
The trigger will act as soon as the electron passes the detector.
What if I use an excited atom and a photon detector. The experiment is still valid?
What is the operator for the eigenstates {|dead>,|alive>}? Uh…I need some device and description of acting. What is operator for {|decay>,|not decayed>}?

I guess the wavefuction for {neucleus and environment) is very different in each cases. The case when I include a detector or not. When I put the neucleus in a small containment or not, to prevent the cat detecting the radiation. And even the size of containment matters when gamma particle(photon) is emitted.
I guess my these questions can be answered without any interpretation. Very physical questions(?)… Hmm…Are they nonsense questions?

Decoherence ultimately doesn’t explain anything; that’s the problem. If you want to claim that it’s QM all the way up, the ultimate question is then turned into, ‘why do we only perceive one branch of the wavefunction’ which is fuzzy enough to make me run away.

Is this because we’re working with an ensemble of decohering environments rather than a specific one? That is, the result of decoherence is a multi-branch wavefunction because it is an ensemble average across decohering environments. If we could follow a particular case, we’d always end up with one branch? (we wouldn’t be happy with a measuring apparatus that didn’t do this).

A Fifth Force?

Often times model changes help perspective, where previously idealization will be contained. Moving beyond the “experimental grasp” for new ways in which to interpret, require a mode and offensive into producing “new variations of ole things held in context”?

In the Schrödinger’s Cat gedankenexperiment, this uncertainty is put to good (?) use by closing the box with the Cat in it and then refraining from looking inside for a while. Did that radioactive atom decay (thereby triggering the Cat-killer apparatus) or not? Until we open the box and look inside, we don’t know; we only know the probability.

And this is where the interpretational issue arises: deos this mean that until we open the box and look inside, the Cat is in a superposition state of |dead> and |alive>? And if so, what does that mean?

I read wikipedia for the Schroedinger’s cat. Maybe I was wrong…
The problem of the cat was that:
“When the cat will die?”

If there’s quite amount of radioactive material, I can apply the half-life time. And can predict that the cat will die within half-life.

But, if there’s only one or several radioactive nuclei, we can’t predict when it will decay. In turn can’t predict when the cat will die. If the cat is very lucky, it can survive forever.

This is why I mentioned about quantity and exposure time. And the gibberish, “decaying itself is measurement.” I was forgetting…

Is the wavefucntion of nucleus different from the wavefuction of (an atom plus a photon)? I mean qualitatively(?). I don’t know what this means.: The probability that a nucleus would decay within 1 hour is 1/2.

Really, if there’s only one nucleus, the cat may survive for long time, even though half-life is just an hour.
Where am I wrong? Anybody, any comment?