Quantum physics

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Does anyone here know a lot about quantum physics?

I have recently become interested in it, and have started off by reading popular introductions to the subject, before I start trying university level texts or original papers. This can be a bit frustrating because they tend to leave out the maths (and my maths probably isnt good enough to understand it anyway yet), but there was a certain point that hit me yesterday and I couldn't work out why they had made the conclusions they had.

Apparently there was an important paper published by Einstein, Podolsky and Rosen where they tried to show that particles must have determined properties (position, velocity and spin etc) and the failure of quantum mechanics was in not being able to determine all these properties at the same time (position can be determined, but this means velocity cannot and vice versa).

John Bell then came up with an experiment which showed that E, P & R were wrong - he said that if the spin was measured from two identically generated particles (having oppositely identical properties) - spin being either clockwise or anticlockwise, then there is a certain percentage of obtaining opposite results (i.e. one clockwise and one anticlockwise) that indicates that particles have predetermined properties, and less than this precentage indicates that particles are not determined but random, and that determination occurs upon measurement and measurement of one particle determines that the other particle will give the same (opposite) measurement when measured in the same way. He used spin measured on different axes.

The experiment was done, and it was found that the spin seemed to be random rather than predetermined, which meant that the fact that the two particles were always found to have identical (opposite) spin if measured in the same axis meant that there was some sort of 'faster than light' communication between the particles, or quantum linkage such that they can be considered as a single entity, despite being far apart.

Now, maybe this book ('The fabric of the cosmos' by Brian Green) just doesnt go into detail enough and maybe my knowledge of quantum physics is so poor that what I am about to suggest is not viable, but it seems to me that there is a simpler explanation than this strange sort of quantum linkage that so disturbed Einstein and disturbs me also.

We already know that measurement itself disturbs properties of particles and this makes sense. If three possible axes are considered - X, Y and Z, then if X is measured on the first particle it will always be equally opposite to that measured on its sister particle. But (as I said above), random measurement of axes leads to results that suggest the measurements are not always correlated and that there is randomness before measurement. What I am wondering is whether the measurement at one axis is affecting the potential (but unmeasureable) results at other axes.

If the particle is measured at the X axis, then it may be predetermined to have clockwise spin at X axis, anticlockwise spin at Y axis and clockwise spin at Z axis (even though the other two axes cannot be measured). However, if measured at the Y axis this could alter the values such that the Y measurement is now clockwise (and the X determined also as clockwise and the Z as anticlockwise perhaps).

What this would mean is that the particles can be predetermined and do not have a quantum connection, but just equal and opposite predetermined qualities, that can be affected by measurement, thus giving the impression of randomness when measured at different axes, but identity when measured at the same axis.

Does this make sense? I can't do the maths and maybe it wouldnt work - maybe there is a perfectly good explanation why this is no good and maybe it has been discussed and refuted previously. I am sure with more reading I could find out the answer, but this could take years with my current limits on free time, so I thought asking any potential quantum physicists out there would be a better idea.

I don't know...I gave up when I couldn't figure out if I opened the box whether the cat would be alive or dead...

if i were you id be getting a good grounding in basic physics, maths and chemistry. dont know if you studied it at high school (even if you find it boringly simple like i did) but thats where you should start. then move up. i began reading the descriptions of different physics fields like reletivity, quantum mechanics, etc. in encyclopedia articles. This was when i was about 14 so that was ok to understand, however, i hadnt yet learned the basics so when i began reading papers, some of it was above me. Then try to find a uni curriculum for physics. it will tell you what students learn in the 3 or 4 years there. follow that in depth.

I simply dont have the time to begin studying it again, work and other aspects of life take precidence now. But i do read the odd scientific magazine trying to keep up with it. One day, if i have the time, i'll restart in the manner i just described and go all the way. I really wouldnt mind going to University and earning an astrophysics degree. If you like, post up here some of what youve been thinking about the subject and id be happy to discuss it with you. some others here might join in too.

For other discussions, try the www.space.com forums. there are a number of physics academics who regularly put their two cents in there. you just have to sift through some of the amatuer crap.

If you understand the Schrödinger's Cat in a box situation and the Particle-Wave duality, then wuantum physics shoul not be that much of a challenge contrary to popular belief.

I have studied physics up to A level (end of high school), plus maths and further maths and chemistry and I was good at all of them. However, this was a long time ago and we didnt learn a huge amount about quantum physics. This is why I think I can start at university level (although maths needs some refreshing). I am a biologist and have become interested in quantum physics through the possibility that it could be involved in a non-trivial way in biological processes (i.e. not simply just in how molecules are held together at the micro level, but in a more fundamental way - for example in the origin of life or consciousness). I don't know if these theories are any good, basically because I don't know enough about the potential of quantum physics.

I don't have a problem with things being counterintuitive, if there is good evidence for them. Its just that from what I have read it often seems as though there are other possible explanations for things. I also have a huge problem with chance - I am not sure there even is such a thing, or whether it is a word we use because we cannot understand the cause and effect properly. I am starting to think that there is something fundamentally wrong with quantum theory, but I don't know whether that is possible or whether it is just a case of me not knowing enough about it yet. Maybe our current theories fit the experimental data, but this doesn't mean they are the only possible theories.

If you want to really really continue with this study keep in mind that you can't always believe everything you read in books, no matter how brilliant the author is said to be. You also need a certain level of instinctive intuition about the things around you so you can discern which paths to follow and which to abandon. Understanding quanta is a bit like understanding Zen in that both require a somewhat blank internal slate in order for the process to proceed unimpeded.
Contraty to popular myth many of the leading ground breakers of the past were not smart people but they just didn't give up easily.

From http://math.ucr.edu/home/baez/physics/Q ... ality.html

• J. Bell: "On the Einstein Podolsky Rosen paradox" Physics 1 #3, 195 (1964).
• J. Bell: "On the problem of hidden variables in quantum mechanics" Reviews of Modern Physics 38 #3, 447 (July 1966).

Well I thought it looked more like algebra than physics.

Sorry to have wasted your time sir.
But then I rather think you enjoyed pointing out how ignorant I am of the things that I asked.

While I have taken QM classes, I can't tell you much of anything about it, a combination of me having a crappy teacher for the subject (he knew it damn well, just couldn't teach it) and it not being the focus of my degree (and therefore promptly forgotten for the most part when I was studying more important things for my degree). However, I can tell you, it isn't just simple algebra, there's a lot of complex differential equations (it's a junior-level class for a reason) and usage of non-real numbers for the proofs behind a lot of the theories. For the most part, the equations we used weren't about specific values, but about what has the highest probability density (such as molecular orbitals).

One useful quote from the professor, though:
"Don't try to visualize this, no one can. It will only make the material harder for you to learn."

I never really studied quantum mechanics, but I seem to recall there was quite a bit of "algebra" from what I recall...