The Decoherence of Measurement


By Sam Vaknin
Author of "Malignant Self Love - Narcissism Revisited"

Arguably the most intractable philosophical question attached to Quantum
Mechanics (QM) is that of Measurement. The accepted (a.k.a. Copenhagen)
Interpretation of QM says that the very act of sentient measurement
determines the outcome of the measurement in the quantum (microcosmic)
realm. The wave function (which describes the co-existing, superpositioned,
states of the system) "collapses" following an act of measurement.

It seems that just by knowing the results of a measurement we determine its
outcome, determine the state of the system and, by implication, the state of
the Universe as a whole. This notion is so counter-intuitive that it
fostered a raging debate which has been on going for more than 7 decades
now.

But, can we turn the question (and, inevitably, the answer) on its head? Is
it the measurement that brings about the collapse - or, maybe, we are
capable of measuring only collapsed results? Maybe our very ability to
measure, to design measurement methods and instrumentation, to conceptualize
and formalize the act of measurement and so on - are thus limited and
"designed" as to yield only the "collapsible" solutions of the wave function
which are macrocosmically stable and "objective" (known as the "pointer
states")? Indeed, pointer States are reminiscent of the "strange attractors"
of chaos theory!

Most measurements are indirect - they tally the effects of the system on a
minute segment of its environment. Wojciech Zurek and others proved that
even partial and roundabout measurements are sufficient to induce
einselection (or environment-induced superselection). In other words, even
the most rudimentary act of measurement is likely to probe pointer states.

Superpositions are notoriously unstable. Even in the quantum realm they last
an infinitesimal moment of time. Our measurement apparatus is not
sufficiently sensitive to capture superpositions. By contrast, collapsed (or
pointer) states are relatively stable and lasting and, thus, can be observed
and measured. This is why we measure only collapsed states.

But in which sense (excluding their longevity) are collapsed states
measurable, what makes them so? Collapse events are not necessarily the most
highly probable - some of them are associated with low probabilities, yet
they still they occur and are measured.

By definition, the more probable states tend to occur and be measured more
often (the wave function collapses more frequently into high probability
states). But this does not exclude the less probable states of the quantum
system from materializing upon measurement.

Pointer states are carefully "selected" for some purpose, within a certain
pattern and in a certain sequence. What could that purpose be? Probably, the
extension and enhancement of order in the Universe. That this is so can be
easily substantiated by the fact that it is so. Order increases all the
time.

The anthropocentric (and anthropic) view of the Copenhagen Interpretation
(conscious, intelligent observers determine the outcomes of measurements in
the quantum realm) associates humans with negentropy (the decrease of
entropy and the increase of order).

This is not to say that entropy cannot increase locally (and order decreased
or low energy states attained). But it is to say that low energy states and
local entropy increases are perturbations and that overall order in the
Universe tends to increase even as local pockets of disorder are created.
The overall increase of order in the Universe should be introduced,
therefore, as a constraint into any QM formalism.

Yet, surely we cannot attribute an inevitable and invariable increase in
order to each and every measurement (collapse). To say that a given collapse
event contributed to an increase in order (as an extensive parameter) in the
Universe - we must assume the existence of some "Grand Design" within which
this statement would make sense.

Such a Grand Design (a mechanism) must be able to gauge the level of
orderliness at any given moment (for instance, before and after the
collapse). It must have "at its disposal" sensors of increasing or
decreasing local and nonlocal order. Human observers are such
order-sensitive instruments.

Still, even assuming that quantum states are naturally selected for their
robustness and stability (in other words, for their orderliness), how does
the quantum system "know" about the Grand Design and about its place within
it? How does it "know" to select the pointer states time an again? How does
the quantum realm give rise to the world as we know it - objective, stable,
certain, robust, predictable, and intuitive?

If the quantum system has no a-priori "awareness" of how it fits into an
ever more ordered Universe - how is the information transferred from the
Universe to the entangled quantum system and measurement system at the
moment of measurement?

Such information must be communicated superluminally (at a speed greater
than the speed of light). Quantum "decisions" are instantaneous and
simultaneous - while the information about the quantum system's environment
emanates from near and far.

But, what are the transmission and reception mechanisms and channels? Which
is the receiver, where is the transmitter, what is the form of the
information, what is its carrier (we will probably have to postulate yet
another particle to account for this last one...)?

Another, no less crucial, question relates to the apparent arbitrariness of
the selection process. All the "parts" of a superposition constitute
potential collapse events and, therefore, can, in principle, be measured.
Why is only one event measured in any given measurement? How is it
"selected" to be the collapse event? Why does it retain a privileged status
versus the measurement apparatus or act?

It seems that preferred states have to do with the inexorable process of the
increase in the overall amount of order in the Universe. If other states
were to have been selected, order would have diminished. The proof is again
in the pudding: order does increase all the time - therefore, measurable
collapse events and pointer states tend to increase order. There is a
process of negative, order-orientated, selection: collapse events and states
which tend to increase entropy are filtered out and statistically "avoided".
They are measured less.

There seems to be a guiding principle (that of the statistical increase of
order in the Universe). This guiding principle cannot be communicated to
quantum systems with each and every measurement because such communication
would have to be superluminal. The only logical conclusion is that all the
information relevant to the decrease of entropy and to the increase of order
in the Universe is stored in each and every part of the Universe, no matter
how minuscule and how fundamental.

It is safe to assume that, very much like in living organisms, all the
relevant information regarding the preferred (order-favoring) quantum states
is stored in a kind of Physical DNA (PDNA). The unfolding of this PDNA takes
place in the physical world, during interactions between physical systems
(one of which is the measurement apparatus).

The Biological DNA contains all the information about the living organism
and is replicated trillions of times over, stored in the basic units of the
organism, the cell. What reason is there to assume that nature deviated from
this (very pragmatic) principle in other realms of existence? Why not repeat
this winning design in quarks?

The Biological variant of DNA requires a biochemical context (environment)
to translate itself into an organism - an environment made up of amino
acids, etc. The PDNA probably also requires some type of context: the
physical world as revealed through the act of measurement.

The information stored in the physical particle is structural because order
has to do with structure. Very much like a fractal (or a hologram), every
particle reflects the whole Universe accurately and the same laws of nature
apply to both. Consider the startling similarities between the formalisms
and the laws that pertain to subatomic particles and black holes.

Moreover, the distinction between functional (operational) and structural
information is superfluous and artificial. There is a magnitude bias here:
being creatures of the macrocosm, form and function look to us distinct. But
if we accept that "function" is merely what we call an increase in order
then the distinction is cancelled because the only way to measure the
increase in order is structurally. We measure functioning (=the increase in
order) using structural methods (the alignment or arrangement of
instruments).

Still, the information contained in each particle should encompass, at
least, the relevant (close, non-negligible and non-cancelable) parts of the
Universe. This is a tremendous amount of data. How is it stored in tiny
corpuscles?

Either utilizing methods and processes which we are far even from guessing -
or else the relevant information is infinitesimally (almost vanishingly)
small.

The extent of necessary information contained in each and every physical
particle could be somehow linked to (even equal to) the number of possible
quantum states, to the superposition itself, or to the collapse event. It
may well be that the whole Universe can be adequately encompassed in an
unbelievably minute, negligibly tiny, amount of data which is incorporated
in those quantum supercomputers that today, for lack of better
understanding, we call "particles".

Technical Note

Our Universe can be mathematically described as a "matched" or PLL filter
whose properties let through the collapsed outcomes of wave functions (when
measured) - or the "signal". The rest of the superposition (or the other
"Universes" in a Multiverse) can be represented as "noise". Our Universe,
therefore, enhances the signal-to-noise ratio through acts of measurement (a
generalization of the anthropic principle).

     References
       1.. Ollivier H., Poulin D. & Zurek W. H. Phys. Rev. Lett., 93.
220401 (2004). | Article | PubMed | ChemPort |
       2.. Zurek W. H. Arxiv, Preprint
http://www.arxiv.org/abs/quant-ph/0105127 (2004).



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AUTHOR BIO (must be included with the article)



Sam Vaknin ( http://samvak.tripod.com ) is the author of Malignant Self
Love - Narcissism Revisited and After the Rain - How the West Lost the East.
He served as a columnist for Global Politician, Central Europe Review,
PopMatters, Bellaonline, and eBookWeb, a United Press International (UPI)
Senior Business Correspondent, and the editor of mental health and Central
East Europe categories in The Open Directory and Suite101.

Visit Sam's Web site at http://samvak.tripod.com