So yeah, in my intro post I said I was into QM this year.  Why at 61 try to understand this theory, which even many smart, smart scientists canât wrap their heads around?  Well it was because there was a news release recently about quantum entanglement (see http://www.cnet.com/news/physicists-prove-einsteins-spooky-quantum-entanglement/ or The Economist: http://www.economist.com/news/science-and-technology/21676733-one-weirdest-bits-physics-proved-beyond-doubt-almost-hidden-no-more ) and how loopholes regarding FTL action at a distance were closed.  This is astounding stuff!  So I tried to read the actual paper.  Was able to actually find a free version following a link (which I canât find now).  (The paywall version is located at http://www.nature.com/nature/journal/v526/n7575/full/nature15759.html .) I couldnât make heads or tails of what they were doing and realized I needed to learn at least the jargon if not the theory to have a better chance at understanding what they were up to.  After all the implications of FTL information transfer are enormous -- they have been well investigated by the Sci-fi community for many years.  But suppose you can quantum entangle some electrons say at Palo Alto, embed them in the iPhone, and then also change state of one while detecting this change remotely.  This is instantaneous information transfer and would eliminate EM radiation as the predominant info transfer medium.  It would mean you no longer need a carrier.  It would break causality, since modern physics defines causality by the light cone.  Was it even possible that the researchers broke the current notion of causality? Â
So then I started researching QM.  Thought I had a good DOVER paperback (love these books; the typesetting of the math is a thing of beauty) on QM, but alas came up short on that.  (Altho I did find the Dover book on Mathematical Physics by Menzel, which is helping refresh and expand my maths, so i can begin to understand some QM.)  However, synchronicity came to the rescue and my COURSERA notices showed the Ludwig-Maximilians-Universität Mßnchen (LMU) was doing a course on quantum optics so I signed up to audit same.
One interesting side note, this course assumed some fairly deep prereqâs, including Maxwellâs Eqâs, wave theory, and beginning QM. Â So I was jumping in without enough background. Â The first lecture totally threw me when they showed this notation: <E|, |H>, Â and similarly <E|H> . Â What the hell did this mean? Â Well of course I turned to Google to try to find this. Â Try finding this using Google! Â Even downloading compendiums of mathematical notation was no help. Eventually though through a very long process of searching I came to understand this was Dirac notation for the bra and ket vectors and the inner product (a generalization of the dot product) of the two. Â (youâll get some very good Wikipedia entries explaining this if you search for Dirac notation.) Â In fact now I have an e-book on loan for Kindle which is going into great detail on this and helping me understand vector spaces and inner products much better than I had before.Â
Right now I am contemplating buying a QM textbook (have my eye on another Dover paperback) but trying to work through what Iâve got first and of course finish the QM optics course. Â
What does this all mean and where does it lead? Â Hard to say at this moment, but just starting to understand how different is the QM world and when you realize it underlies reality, should make your perception of reality quite different, when you think about it. Â Again this issue has been explored in Sci-fi as well as modern philosophy, and indeed if I want to write that Sci-fi book one theme option is how a complete understanding of the core basis of reality enables certain powers to manifest. Â Sort of a compounding of QM with the Buddhist mindset that reality is not what it seems on the surface and a Dharma exists that if understood (to the enlightened) opens up immense possibilities. Â Â
BTW, back to the Delft experiment claiming instantaneous action at distance. Â After a re-read of the press releases it is not clear that they are actually transmitting information, they seem to be just reading the spin state, not changing it and then reading it. Â So if the former, then information is still not being transmitted FTL. Â And from what I recall of the original paper, the spin state entanglement was induced by laser from a central location. Â Which still means the spin state information is traveling at light speed to both locations. Â If just the detection information actually occurs FTL, this really doesnât break causality as I understand it. Â If there is a reader of this who knows better how this experiment worked, I would love to get input / correction on this!