Comments on: No reasonable definition of reality could be expected to permit this

By: Doug

Doug — Wed, 04 Jan 2006 21:15:29 +0000

I would like to ask a question that someone reading this blog is likely to be able to answer: In the case of the double-slit experiment, in the one photon-at-a-time mode, why doesn’t the space between the slits cause the wave function to collapse at the slotted barrier? If the slotted barrier consists of photographic film, then the wave function of all photons impacting it should collapse to some point on the slotted-barrier and be recorded, and, since some of these points will be located at the slits, the photon impacting at that point will not be absorbed by the emulsion when the wave function collapses. However, the collapsed wave function must then re-expand, when the photon emerges from the slit, right? But how can that happen?

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

By: anonymous

anonymous — Tue, 03 Jan 2006 05:19:19 +0000

“it’s generic probability theory.”
I got it. How slow I am…

By: Plato

Plato — Sat, 31 Dec 2005 14:55:44 +0000

Here’s a fast forward from Bell.

WE should, still worry?

By: Elliot

Elliot — Sat, 31 Dec 2005 03:11:47 +0000

I used to worry a lot about what QM means. I finally came to the conclusion that the only “reasonable” interpretation resolving the reality vs. locality question was to define “reality” in information theoretic terms. I can then preserve the “common sense” definition of locality while redefining reality as such:

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

By: Plato

Plato — Fri, 30 Dec 2005 18:17:26 +0000

Maybe the examples are then in how we use the math models for apprehension of what is taking place in our universe?

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?

By: Thomas Larsson

Thomas Larsson — Fri, 30 Dec 2005 10:28:58 +0000

One problem with the interpretation of QM is that the formalism implicitly assumes a macroscopic classical observer. Namely, the Hamiltonian formalism assumes a foliation of spacetime, i.e. an immutable time function. But to observe a system we need to interact with it. This interaction will transfer momentum to the observer, making her undergo a Lorentz transformation, and change the definition of time (if we define time as the ticks of the observerÂ´s clock). By assuming that time is independent of observation we ignore this effect, which seems to me a serious flaw in principle, although unimportant in practice.

By: Cat

Cat — Fri, 30 Dec 2005 08:41:08 +0000

PS: uh, I want to change the word “entangled” to some other word.

By: Cat

Cat — Fri, 30 Dec 2005 07:59:42 +0000

Paul Valletta:”that the probability of observing an ‘event’, decreases with the number of Photons.” In a little bit easy words or with example…?

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.

By: Plato

Plato — Fri, 30 Dec 2005 06:11:46 +0000

Maybe the question above can be put in context of "Which way"? 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??

By: Paul Valletta

Paul Valletta — Fri, 30 Dec 2005 04:09:41 +0000

What occurs in QM and in GR, is that the probability of observing an ‘event’, decreases with the number of Photons. Being that photons are the energy needed for observation by ‘observers’, what happens to a system when the limit of observation is at a minimum ie single photons?