@DavidZaslavsky: Is it considered poor form to nag people about accepting answers?

@user1504 It's fine to leave a comment saying something like "If you think this answer was the most helpful, you can accept it by clicking the green checkmark"

But saying "Please accept my answer" is not okay

And repeatedly reminding someone to accept is also frowned upon

I wasn't intending to advocate accepting my own answer. I noticed a question with a good unaccepted answer, then noticed that the OP asks a lot of good questions and gets a lot of good answers, but has an accept rate in the single digits.

Oh, I see. Well the same rules more or less apply in that case, in that leaving an isolated reminder or two is fine

but don't repeatedly bug someone

And also the thing about making sure it's a reminder, not an order

Honestly, it's not something we (mods) are likely to care about unless you do it a lot

Shouldn't be a problem. I'm usually not all that aggressive in my comments.

Yeah, I wouldn't worry about it if I were you.

@annav Does light reflecting off the "particle" affect it, collapsing the "wave"? If so, then I wonder how people used to say the quackery they'd say about looking at it affecting it. How could they have believed that? Since surely, if the lights were on in the room, then even if they weren't looking at it, it'd affect it, wouldn't it?

@ChrisWhite then wouldn't they have found that looking at it doesn't necessarily collapse it? Why did people used to say that looking at it collapses it? I mean, sure they didn't know the cause of the collapse, but how could they even have made that mistake, if it in that situation - looking at it - it wouldn't necessary collapse. so sometimes they'd have looked at it and it'd have given an interference pattern

I mean, they'd have seen that it'd have given an interference pattern in some cases. So how could they have even made the mistake of saying that looking at it causes the wave function to collapse? if sometimes they'd have looked at it and it not collapse?

@ChrisWhite I have ever avoiding the final year labs by choosing mathematical physics.

Certainly, there are more interesting courses out there. But the main reason is that I have problem to work on experiments that I dont understand.

Usually, you know nothing about the experiment before you actually do that. You spend hours to fix the problems because you dont know what you are working on is very frustrating. And after the lab, you may still know nothing about what you are working on.

It is particular true for those upper undergraduate lab.

@barlop You should peruse the article on quantum decoherence en.wikipedia.org/wiki/Decoherence . In principle, theoretically, since we are all composed by elementary particles, and since there exist quantum mechanical solutions for all that exists,

one could write a humongous matrix , where at each instant ( we are ignoring relativities here) all the values of the matrix elements would be written, one series of functions on the side, the same on the top, defining the matrix, and in the matrix the squared probability. Where functions are entangled there

will be nXn regions on this matrix showing the probabilities for measuring them there. The thing is that the numbers are so humongous, 10^23 paricles per mole, that what you would see macroscopically, i,e, including huge swaths of these columns and

rows, would be the diagonal, which would have the value of 1(summing the tiny nXn) sub matrices statistically. That is the way the transition from quantum to classical happens, statistically due to the enormous numbers involved

Every interaction affects the particle and changes probability values. The amount of change will depend on the interaction. As the modified slit experiments show one can construct experiments where interaction is minimal and the intererence pattern in space appears. But as one should know by experience, and not only by the law of entropy, it is easier to disorder things rather than create or retain order

@ChrisWhite Playing equipment is fun, but fail to finish a lab is not ;)

BTW, I just find that a high value of bounty does not necessary attracted more attention and better answers to a question. Probably I should use a small bounty next time...

@annav ok, but macro aside. Chris said " looking at the particle is in some cases the best determining factor for whether or not collapse happens" If this is so then it means sometimes you can look and get an interference pattern. I don't quibble with that. But what I then ask, Didn't the quantum theorists used to think that observation was always disturbing it enough to collapse the wave function? That is also how the quantum theorists used to know it was being disturbed.

the wave function collapsed

and they thought it was inevitable when looking at it or observing it

So my question is how could they have thought that, if as Chris says, "looking at the particle is in some cases the best determining factor for whether or not collapse happens""

When dealing with quantum mechanics one has to deal with several meta levels. If you do not know the concept of "meta level" look at en.wikipedia.org/wiki/Meta . There exists the original level, lets say proton photon scattering. That is described completely by quantum mechanical solutions.

How do we study it, though? We use detectors, where secondary products of the scattering leave a trace which traces a computer reads, which data a student forms in a historgram which then is fitted to the quantum mechanical solutions. In the beginning of quantum mechanics study there were not many experiments and not much thought /study was spent on thinking about the transitions between levels.

The first rough two slit experiments which due to the size of the slits that had to be comparable to the wavelength made the uncertainty relation the determinant of trying to study the interference pattern. Later experiments went on another level, studying secondary interactions which could intervene as a level still keeping a quantum mechanical wavefunction intact, though a more complicated one

In the proton photon scattering for example, it is evident that collapse has happened, i.e. the proton has a probability of 1 to follow the track after scatter, if you look at some bubble chamber pictures. In interference experiments with electrons

as seen in the link I gave you, the particles statistically show that the probabilities in space were still distinct. In this bubble chamber imglib.lbl.gov/ImgLib/COLLECTIONS/BERKELEY-LAB/… all the observed particles have "collapsed" in classical trajectories. The meta levels are the ions which are disturbed

and create tracks, the photographic equipment and then the obesver.

that was for @barlop

@DavidZaslavsky @Manishearth Would you guys consider a question asking for journal references in a particular sub-field to be on-topic? Things like impact factor alone don't help because they often are split into very narrow fields and I'm having trouble finding consistently high quality journals for this field

You mean something like "what are the good journals in this field?" I would consider that off topic, but I don't think it's ever been explicitly discussed

Yes, something like that...

For example, if somebody asked what the most important journals are in fluid dynamics, that answer is different than computational fluid dynamics, or experimental fluid dynamics

Even though impact factors don't make that distinction, so it can be hard to find good information on sub-fields unless you are in them

Which makes it an "expert" kind of question I suppose

Not that I'm asking about fluid dynamics, I know those journals :)

Would I be better off asking on Meta first?

You can always ask on meta, nothing wrong with that

I can't predict what the community would say, but IMO that falls in kind of the same category as book recommendations

Fluids is similar

Depending on which sub-field you are interested in of course

The "big" ones are all the same, but the half-dozen other useful ones change

Posted, we'll see what folks say

@annav Would you say that there is a mathematical wave probability distribution, once the proton is fired and for the amount of time it takes for a proton to reach the screen and make the pattern of 2 waves interfering with each other. But once time for a proton to hit the screen elapses, then the mathematical wave becomes a real wave at the point where the screen is thus causing the pattern?

I phrased that "would you say that" badly, 'cos you most probably wouldn't say that.. But what I mean is, what's wrong with my formulation there?