Reminder
Wigner argues that during a measurement on a quantum system, the result of which is one of the eigenstates, of the wave function with the associated probability [1], it is at the moment when the experimenter (a consciousness) becomes aware of the result of the measurement that the decoherence of the superposition state of the wave function occurs.
Recall that to obtain information by a measurement (which will produce one of the eigenstates with a certain probability see [1]) it implies a decoherence of the superposition of states of the quantum system to produce this eigenstate.
Comment
This proposal, which seems iconoclastic, which is not the one that is conventionally retained, nevertheless has the advantage,
- on the one hand, to include a human consciousness in the physical process under consideration, which is conceptually very important, because we must not forget that, on the one hand, science is a human activity and that we are not « outside » the universe because we are part of it and as such are intimately dependent on it (we ourselves are made up of atoms), even against our will and
- on the other hand, that a quantum device intended to carry out a measurement (an experiment) of a quantum effect is a human construction aimed at highlighting a property of physics, incorporating all the theoretical ingredients suitable for producing the desired effect [2].
- on the other hand, it also makes it possible to satisfy the principle of preservation of the information resulting from the measurement which, thus transferred to a consciousness, is not lost, whereas without transfer to this consciousness, the information related to this result, known to no one, would be lost….
- Indeed, as the Young’s slit experiment shows, for an experiment to produce information, the experimental design must produce information about the system under consideration [3]. But if this information is not transferred, in the end, to a human consciousness, it is lost, making experimentation sterile.
[1] See https://vous-avez-dit-bigbang.fr/wp-content/uploads/2022/02/Mecanique-quantique-1.pdf, in particular slides 95-100.
[2] Bachelard, in his book « The New Scientific Spirit » considers that an experiment is the materialization of one of the elements of a theory: there is a structural morphism between the theory and the measuring apparatus.
[3] To know whether the photon passes through one slit or the other, you need a detector attached to a slit. Note that if the photon passes through the other slit, the detector does not activate, but given the device, it is concluded that it has passed through the other, this can be verified by the « point » impacts on a screen behind the slits (no interference fringes). We have information.
In the absence of a detector, we obtain interference fringes and it is impossible to know through which slit the photon has passed, assuming that this makes sense: no information in this case.