Interaction probability ; symmetry of the time direction
• One may consider that the wave does not completely describe the
physical process but only a kind of convolution between the sender's
offer and the receiver's “retroactive” demand, which would be filtered
in a global way by those symmetries of apparatus that are contained in
interaction hamiltonian.
Thus the fundamental property of a particle with respect to quantum
mechanics may be its interaction probability and not its presence
probability (the ambiguousness comes from the fact that in order to
detect the presence of a particle one must interact with it). But as we
know nothing of the world apart from interactions that we have with it,
the quantum description is sufficient for us to predict (statistically)
the results of all the measures.
This may cause some difficulties (or even impossibilities) for
experimental verification. The existence of free particles asymptotic
states may thus be questioned back : if the Universe would contain
some matter only “in one side” of a given particle sender,
who can say if this apparatus would emit symmetrically ? Do the
eventual
particles leaving the apparatus to the “empty” side and never
reinteracting
exist ?
A sender isolated in an “empty” space would it be able to emit a photon
(if it already “knows” where it is coming to as early as it starts,
where would it go ?) ? Then, if the sender does not emit, is it not
possible to consider that its “time” does not elapse ? All this may
lead to experimental situations showing new phenomena (similarly to
Casimir's effect [1]).
It would be necessary for that to be able to produce (as example) an
isolated atom in such an excited state that it could desexcite only by
emitting photons with a precise frequency (at a temperature necessarily
very close to 0 K), placed in a cavity “totally” anti-resonant for the
frequency in question, and then to test its ability to desexcite in
these conditions.
In practice, this kind of situation does not clearly appear since it is
certain that the particles involved in experiments are finally doomed
to
reinteract ; but nothing forbids to assert that if one sets a receiver
in a given configuration, one forces (through the wave and the
associated instantaneousness) the particles reaching this one to be in
some
states that it is able to detect. In the absence of any receiver, the
particles
going this way would not necessarily have been in one of these states,
but they would nevertheless have been in similar states since they
would necessarily travel within the course to another interaction.
Moreover, in the case of a Young's fringes experiment with
hyperboloid-shaped interference sheets, nothing forbids on principle
the particles to go through the dark regions without interacting (their
interaction probability vanishing with the wave) to reach an
interaction in a light region located behind. The knowledge that
we can have about particles trajectories thus becomes very hazy since
we only have access to the interaction probability (more especially as
some physicists even consider interaction in further space-time
dimensions).
• From another point of view, beside the sender-receiver
symmetry appears a
macroscopic dissymmetry between past and future : if one
places two identical sources of light in front of a receiver, this one
detects twice more photons,
whereas if one places two receivers in front of a source, the
source does not emit twice more.
But this may be explained, while keeping the microscopic influence of
the receiver on the source, by the fact that we live in a world where
energy is rare, bounded on the under side and not on the upper one. The
receivers demand is very large (every system able to interact behaves
as a receiver) and they
detect all that is offered to them, thus twice more if one
doubles the source (linear behavior). On the other hand, the sources
offer is very weak (little available energy) and they have a saturated
behavior, apparently
independent of the very large number of receivers
(nothing seems changed if one modifies a few
receivers among a very large number). This
dissymmetry is thus fully compatible with the microphysical
symmetry between sender and receiver.
Inversely (accordingly to the temporal symmetry for
interactions), some effects like induced absorption would they not be
considered (“inverse Laser” effect for which it might be considered the
phase coherence, but unlikely the amplification, according to the
previous remark) ? It may be considered for that to reinterpret in
reverse direction
(within the relativistic instantaneousness approach) the “usual”
diagrams, while being careful to respect the direction of interactions
; thus, it is usually considered that spontaneous absorption and
induced absorption are “naturally” proportional to the flow of incident
photons, therefore it is noticed that spontaneous emission is
independent of the incident flow, whereas it would be more consistent
to consider that it is proportional to the emitted flow (in the same
way as spontaneous absorption is independent to the emitted flow...),
and then to think about a possible effect of induced absorption,
proportional to the emitted flow (within hypothetical conditions where
there would not be “saturation” of emittors by limitation of the
available energy) [2].
If such effects don't appear in usual
situations, they might occur in extreme situations, as example in very
high energy ions collisions [3]. But moreover, it would seem rather
logic that this kind of effect might participate in the explanation of
photons coalescence.
In the case of two photons coming from two independent sources of
single photons and joining
together at the time of passing through a semi-reflecting plate : while
increasing the indiscernibility of the photons, one reduces the
relative probability for them to be accepted by uncorrelated detectors
and favours the induced absorption [4].
• Elsemore, through the permanent contact imposed by the generalized
instantness between senders and receivers, one can rejoin statistical
aspects assignable to a hidden thermodynamics for particles. As an
example, if a source of light is
confronted with the demand of many receivers, the state of some
receivers may be modified, among other things by the arrival of a
photon coming from another source. Thus, because of the large number of
the receivers, the demand is unceasingly fluctuating (although
stationary on an average) and one may consider that a train of waves is
nothing but the state which takes place between two
fluctuations ; the equations of quantum mechanics then representing a
kind of thermodynamical flow
between a hot source (sender) and a cold source
(receiver) [5].
• What does happen therefore in the experimental case of the
Einstein-Podolski-Rosen paradox ? Let us thus consider a source
S emitting correlated particles pairs in the
direction to two receivers R1 and R2 ; it may be
asked if the wave packet reduction allows a superluminary
communication between the receivers R1 and R2.
The answer is double. Yes in a certain way at the microphysical level,
since when modifying R1 one influences the
detection at the level of R2 ; no in any way at the
macrophysical level, since the modification of the only receiver R1
among the very large number able to interact with the source cannot
modify with appreciable change the global demand received by the
source, and thus cannot modify the statistical
detection at the level of R2.
__________________
References :
1. see as example :
“L'infiniment vide n'existe pas”,
T. Boyer,
Pour la Science n° 278, december 2000 ;
“La force qui vient du vide”, A.
Lambrecht, La Recherche n° 376, june 2004.
2. see as example :
“Du GPS au DVD”, P. Yam, Pour la
Science n° 326, december 2004 ;
“Les fluctuations d'Einstein”, S.
Reynaud, Pour la Science n° 326, december 2004.
3. see as example :
“Le big bang en laboratoire”, C. Roy,
La
Recherche n° 395, march 2006 ;
“Les premières microsecondes de l'Univers”, Pour la Science
n° 344, june 2006.
4. see as example : “Photons indiscernables : qui se ressemble
s'assemble”, I. Robert-Philip et al., Images de la Physique 2006, p.
106.
5. by this aspect, the quantum mechnics is perhaps not independent of
the methods used to describe the flows in production lines ; see as
example : “L'algèbre des sandwichs”, G. Cohen, S. Gaubert and
J.P. Quadrat, Pour la Science n° 328, february 2005.
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