Dear Dr. Diosi,

I'd like to comment on your recent "Anomalies of weakened decoherence criteria for quantum histories", quant-ph/0310181 of Thu, 30 Oct 2003 18:00:56 GMT. You wrote:

"Deriving testable statistical predictions from a given quantum state  [p]  is possible via decoherent histories (DH's) [1, 2, 3, 4, 5], without invoking von Neumann's concept [7] of quantum measurement and state reduction."

If this was possible, the interference terms would be *exactly* zero (no "coarse-grained" blurring, please!), and we would be able, at least in principle, to chain those histories along a time parameter read by a physical clock, and then solve the problem of covariant reduction, which inevitably requires the notion of some non-contextual quantum reality 'out there', just like the Sun,

http://members.aon.at/chakalov/Willem.html

It is not surprising to me that you examined a wrong idea and proved it wrong. More at

http://members.aon.at/chakalov/white_paper.html

A variation on DH's theme can be found in TwoTimes.doc from

http://members.aon.at/chakalov/TwoTimes.zip

Please see there the discussion of C.J. Isham and K.N. Savvidou, "Quantising the Foliation in History Quantum Field Theory", quant-ph/0110161, and of the "quasi-temporal type of dynamical evolution" in Chris Isham's "Quantum logic and the histories approach to quantum theory", gr-qc/9308006.

I believe Fotini can elaborate on the alleged 'quasi-temporal type of dynamical evolution' in great details, since she was Ph.D. student of Chris Isham and knows the subtleties of the continuous analogue of a tensor product, and subsequently its history group presentation.

I regret that you didn't comment on Robert Griffiths' quant-ph/0207015, "Consistent Resolution of Some Relativistic Quantum Paradoxes", in which one can read about a "coarse-grained but fully quantum mechanical description in which particles move along trajectories". The devil is in the coarse-grained details, as you might have guessed. More at

http://members.aon.at/chakalov/Frasca.html#3

I will appreciate your feedback, as well as the professional comments from your colleagues. I will keep them strictly private and confidential.

Sincerely,

Dimi Chakalov
http://members.aon.at/chakalov
--
So one of my missions in life is to get people to see that if they want to talk about the problems of quantum mechanics -- the real problems of quantum mechanics -- they must be talking about Lorentz invariance.

John S. Bell

===

Subject: Re: Consistent decoherent illusions?
Date: Mon, 03 Nov 2003 15:20:55 +0200
From: Dimi Chakalov <dchakalov@surfeu.at>
To: Lajos Diosi <diosi@rmki.kfki.hu>
CC: fotini@perimeterinstitute.ca, k.savvidou@ic.ac.uk,
     C.Anastopoulos@phys.uu.nl, d.brody@ic.ac.uk, i.raptis@ic.ac.uk,
     j.halliwell@ic.ac.uk, j.thorwart@ic.ac.uk,
     Roland.Omnes@th.u-psud.fr, rgrif@andrew.cmu.edu,
     oldstein@math.rutgers.edu, W.M.d.Muynck@tue.nl,
     hartle@big-g.physics.ucsb.edu, hartle@physics.ucsb.edu,
     bassi@ictp.trieste.it, ghirardi@ts.infn.it
 

P.S. I forgot to add that a continuous nondemolition measurement cannot be performed with any inanimate device. With the human brain -- maybe, but what we "measure" is UNspeakable,

http://members.aon.at/chakalov/Vecchi.html

D.C.