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seen Jul 22 at 7:51

Aug
25
comment How can new interpretations of QM help?
@RonMaimon: Not an existing one. Any interpretation that could be found in the future. However, if there is no practical problem to solve, even a new interpretation wouldn't provide new value. Btw, is the work of Hooft considered serious? Did he have any concrete results?
Jun
5
comment Adding 3 electron spins
Thanks. I tried a brute force approach diagonalizing the 8x8 matrix for total angular momentum. The result was img31.imageshack.us/img31/6228/3spins.png. The cyclic operator turned out to be nice and also works for 4 spins. I need to study your approach - I forgot the basics :) A bit surprising that there is no easy answer.
Jun
5
comment Show quantum entanglement to a classical thinker
I'll have to study that paper. Then just a last question. Has there been absolutely no objection to the set up? Because the CHSH inequality should (apart from statistics) allow for a statement no matter what physically happens unexpectedly. Unless there are additional assumptions about physical measurements needed. Of course you do not need 100% correlation but only above a limit.
Jun
5
comment Show quantum entanglement to a classical thinker
Thanks, talks exactly about this question. The answer of Frédéric describes it a bit more, too.
Jun
4
comment Show quantum entanglement to a classical thinker
This is pretty good answer to the question :) Does that mean there is an experiment which is close to 100% winning? It could be an objection if the required state is not realizable. How can I find that experimental test?
Jun
4
comment Show quantum entanglement to a classical thinker
Thanks! This looks quite promising and I have to study this closer! I read the CHSH inequality, but havent got a deeper grasp on it. When a layman asked me what I'm trying to understand, I knew which way I wanted to answer, but wasn't sure how to frame the CHSH this way.
Jun
4
comment Adding 3 electron spins
I cannot access the paper :( [EDIT: link fixed but I'd have to be in the institutite :)] So to get my results (in terms of spins up/down for each particle) I can take the direct sum of them. Then I will get j/jz states on the RHS and I rearrange for them. The basis j/jz is not complete and will give degeneracies once I try to rearrange for terms on the RHS? Is that the part I was missing? Which other quantum number should I use to distinguish between degeneracies?
Jun
4
comment Adding 3 electron spins
I'm not sure if I understand what you describe. Is that example for 3 spins? Eigenstates should consist of a sum of $|xyz>$ combinations where x,y,z are spin up/down?! If you use total momentum and and z-part you will need an additional quantum number. Can you post an answer deriving at least the total spin 1/2 states for 3 electrons? I can asure you many theorists in the department got stuck there.
Jun
4
comment Adding 3 electron spins
@Emilio: I'll keep that as a reference. Supposedly that book offers a solution, but I don't have it and only wanted to know a short outline :)
Jun
4
comment Adding 3 electron spins
@qoqosz: That comment is quite unhelpful. Read the whole question where I already write some objections, that puzzled other theorists who thought "it is straighforward".
Jun
2
comment Deriving Statistical Mechanics laws from Quantum Mechanics?
True, that's what I meant by "presuppositions". You can apply the methods of statmech to anything where (micro)states have equal probability. Entropy laws follow from that. You could equally apply statmech to a set of cards or anything abstract.
May
7
comment why people choose condense matter physics the most in 2007 and 2008 for their phd? And what are they studying and what is application in this subject?
At university we learned that with logic, proper analysis and error analysis every smart person should arrive at the same conclusions. Why are experiments seem to "proof" completely opposite views at the same time? By "more real world applications" I thought that surely discoveries in more practical sciences like engineering are more often useful?! There were very few usable result in CMP in relation to the amount of papers published? Anyway, I hope this answer provides a complementary view from someone who doesn't regret that he quit the academic path for a reason :)
May
4
comment Which new insight did $E=mc^2$ give us?
The moon has simple binding energy to the earth which was way before Einstein. And you could knock out an orbiting object and get energy back. Is binding energy in particular isn't the difference.
Apr
27
comment Which new insight did $E=mc^2$ give us?
You helped me find the answer. In my opinion you just don't get to the point and the "in-depth/fundamental" part was missing. That's as much as I can say. Thanks.
Apr
26
comment When does a pot not spill?
I've found an article to the walking spill problem: pre.aps.org/abstract/PRE/v85/i4/e046117
Apr
26
comment Which new insight did $E=mc^2$ give us?
It's certainly true. Let me try to draw a conclusion which is more the "fundamental insight" part that I was looking for. That splitting nuclei emits energy isn't surprising either due to the known concept of binding energy. But maybe the actual key point is that binding energy can be measure by the gravitational force? The conclusion I see is that kinetic energy can be converted to real particles. Is that the essence?
Apr
20
comment Did they find a new particle with CMP?
Thanks! So it's similar to magnetic monopol discovery. How boring :)
Apr
16
comment Macroscopic laws which haven't been derived from microscopic laws
Very good point! In fact I'm exactly refering to something like "more is different" and asking where such a high level law has been found, which was inaccessible from microscopic ones.
Apr
7
comment When does a pot not spill?
Sharp edges could be part of the answer. I also see different shapes and angles. Moreover it seemed to me an elliptic container drips less from the flatter side. What about the material? And why the fancy shapes of teapots openings?
Apr
7
comment When does a pot not spill?
If you have questions about details just ask. After you have poured the liquid there are often drops dripping. Some cans do that. Some don't.