[LottiFurmann]

On the other hand, the unmeasured photon is still entangled with the measured photon + measuring device system.

I was just trying to scribe a similar thing. I seem to be jumping between abstract hilbert space where superpositions can only exist and classical space where objective properties of objects can only exist. In my mind, and from prior discussions with you I can only objectify a photon in the classical realm when a measurement is undertaken and that property is only derived from the extraction of the properties the measuring device dictates from the original superposition. It seems to me that the measuring device is controlling things here and simply extracting what it wants and not necessarily recording accurately what it detects. It is not a passive player. I could extract a photon from a walrus in this manner if I was simply directing what information to take from the system.....anyway it's time for my pills :-))

[HedgeYourBets]

I was just trying to scribe a similar thing. I seem to be jumping between abstract hilbert space where superpositions can only exist and classical space where objective properties of objects can only exist. In my mind, and from prior discussions with you I can only objectify a photon in the classical realm when a measurement is undertaken and that property is only derived from the extraction of the properties the measuring device dictates from the original superposition. It seems to me that the measuring device is controlling things here and simply extracting what it wants and not necessarily recording accurately what it detects. I could extract a photon from a walrus in this manner if I was simply directing what information to take from the system.....anyway it's time for my pills :-))

By definition, a position measuring device is a macroscopic system whose state depends on the position eigenstates of the quantum system. Likewise, a momentum measuring device is a macroscopic system whose state depends on the momentum eigenstates of the quantum system. And the same is true for all other measurement variables. In other words, a measuring device selects the basis vectors simply because it is those basis vectors that lead to different macroscopic states.

[radikal]

The point is that it is the entire quantum state that interacts with the measurement device and the decomposition of the quantum state into a basis of eigenstates is merely a description of how the quantum state interacts with the particular device. There are no "bad" measurements. A measuring device simply measures what it measures.

[Lillie_Steins]

This illustrates an aspect about the maths of quantum mechanics: one normally doesn't include the measuring device into the description of a quantum mechanical system being measured. In the case of quantum decoherence, the irreversible nature of wavefunction collapse is the result of not including the measuring device in the description, while including the measuring device leads to unitary evolution of the total system wavefunction.

This effectively mirrors my logic in constructing this thread. This and other aspects force me to consider the nature of physical measurement as essentially spatially oriented, where measurement of time related components are examined and interpreted in a spatial context, not within it's own context. Though a thorough examination may possibly still provide a plausible Panspermia mechanism, the focus of this thread would appear to mostly concern the nature of time and the relevance of it's interpretation within measurement. Thanks for the feedback KJW.

[softy54534]

In the many-worlds interpretation, there is no loss of information when a quantum system is measured. When the quantum state interacts with the macroscopic state, there is a one-to-one correspondence between the superposition of macroscopic states and the quantum state (the superposition of its basis eigenstates). It is only because we only see one of the eigenstates of the macroscopic state corresponding to one of the eigenstates of the quantum states that the information associated with the other eigenstates that we don't see is lost. We don't see the other eigenstates because they are orthogonal and do not interfere with the eigenstate that we do see.

Note that quantum mechanics is linear:

If y ® Y and f ® F, then:

ay + bf ® aY + bF

[radikal]

Note that quantum mechanics is linear:

It is this dependence on sequence that I see an issue with in evaluating and interpreting various global phenomena. At this point I am considering if time in a global sense should be considered to develop 'future first', so the observable progression and development of matter therefore can be seen as the balancing of possible momenta rather than a development of it.

[HedgeYourBets]

This effectively mirrors my logic in constructing this thread. This and other aspects force me to consider the nature of physical measurement as essentially spatially oriented, where measurement of time related components are examined and interpreted in a spatial context, not within it's own context. Though a thorough examination may possibly still provide a plausible Panspermia mechanism, the focus of this thread would appear to mostly concern the nature of time and the relevance of it's interpretation within measurement. Thanks for the feedback KJW.

The way I see it, there can only be one possible quantum multiverse, which contains everything that can possibly happen. I tentatively believe the universe started from a pure state of zero entropy, and through self-interaction, decohered to the many possible universes that exist today, but only one of which we can observe. The decoherence continues, increasing the entropy of any particular universe.

[PhillipHer]

The way I see it, there can only be one possible quantum multiverse, which contains everything that can possibly happen. I tentatively believe the universe started from a pure state of zero entropy, and through self-interaction, decohered to the many possible universes that exist today, but only one of which we can observe. The decoherence continues, increasing the entropy of any particular universe.

Might take a little consideration to figure out if I am constructing the same device or a modification.

[softy54534]

The way I see it, there can only be one possible quantum multiverse, which contains everything that can possibly happen. I tentatively believe the universe started from a pure state of zero entropy, and through self-interaction, decohered to the many possible universes that exist today, but only one of which we can observe. The decoherence continues, increasing the entropy of any particular universe.

Can't we explain this without invoking a multiverse?

For example, surely this increase in entropy arises from measurement itself which is designed to 'extract objective information' from the quantum system. If we assume for one moment that when a measuring device is used to determine the 'which way path' of an electron, that the quantum state of the measuring device is looking for a particular objective property attributed to what we call an electron (in our classical realm), then the measuring device will deliberately be configured by conscious observers to possess a specific set of orthogonal basis states that can be attributed to this objective property. As a result, if the quantum state possesses this set of orthogonal basis states they won't interfere with the set of basis states of the interrogating measuring device and lo and behold a classical state will result defining an objective property of this electron.

When the quantum state of the measuring device interacts with the quantum state of the original superposition, a new entangled superposition is created in the quantum world which is expressed in our classical world by the information we extract (the orthogonal basis states) from the original superposition (eg. break the original symmetry) to ascribe an objective state in our classical universe. In our classical reality of course we do not observe the new entangled superposition that remains from the interaction of the measurement as this stays in the quantum realm until we prod it with a new measurement, but what we deduce from the original mathematical superposition is a broken symmetry between the previous state in the quantum realm and the classical realm. We have acquired information about the quantum state and have permanently preserved it in our classical realm. I can see an arrow of time emerging, increasing entropy etc. but this is just a notional 'objective reality' in our classical realm that ultimately can be attributed to conscious observers and the information they wish to extract. The symmetry still exists in the quantum realm as no such decoherence actually occurs. Our classical universe is therefore the 'myth' which has had properties attributed to it by measurement by conscious observers. A grand superposition of 'everything' is still retained in the quantum realm. Rather than using a multiverse proposition then, our classical universe could therefore be interpreted as a conscious observer universe (a bit like a hubble volume) which is a subspace of a greater abstract space. :-))

Edit: An interesting paper here KJW :

The engine that powers quantum cryptography is the principle that there are no physical means
for gathering information about the identity of a quantum system’s state (when it is known to be
prepared in one of a set of nonorthogonal states) without disturbing the system in a statistically
detectable way. This situation is often mistakenly described as a consequence of the “Heisenberg
uncertainty principle.” A more accurate account is that it is a unique feature of quantum phenomena
that rests ultimately on the Hilbert space structure of the theory along with the fact that time
evolutions for isolated systems are unitary. In this paper we shall explore several aspects of the
information–disturbance principle in an attempt to make it firmly quantitative and flesh out its
significance for quantum theory as a whole.

[brraverishhh]

I can't provide an immediate response to your reasoning Copernicus, but this thread is definitely going in the direction I intended.

[NeroASERCH]

Our classical universe is therefore the 'myth' which has had properties attributed to it by measurement by conscious observers. A grand superposition of 'everything' is still retained in the quantum realm. Rather than using a multiverse proposition then, our classical universe could therefore be interpreted as a conscious observer universe (a bit like a hubble volume) which is a subspace of a greater abstract space.

There is a variant of the many-worlds interpretation known as the "many-minds interpretation" in which conscious observers play an essential but passive role in the apparent collapse of the wavefunction. I find it difficult to dismiss this interpretation as the question of why we only observe a single eigenstate does not appear to me to be fully answered by the orthogonality produced by decoherence.

[Lillie_Steins]

There is a variant of the many-worlds interpretation known as the "many-minds interpretation" in which conscious observers play an essential but passive role in the apparent collapse of the wavefunction. I find it difficult to dismiss this interpretation as the question of why we only observe a single eigenstate does not appear to me to be fully answered by the orthogonality produced by decoherence.

Ouch. I am just looking it up now. It is going to take some time to absorb. :-))

[Drugmachine]

The symmetry still exists in the quantum realm as no such decoherence actually occurs.

Decoherence occurs when there is self-interaction within the macroscopic system. It is a consequence of the high-dimensionality of the Hilbert space of a macroscopic system, leading to the orthogonality (as quantum eigenstates) of classical states. The orthogonality of these states is objective, and therefore there is no subjectivity as to what are the classical states, given the quantum state of the macroscopic system.

[Peptobismol]

I should point out that by "self-interaction", I mean interactions such as electromagnetic forces, etc, and not wavefuction interference. Unlike quantum mechanics, these interactions are non-linear.

[tgs]

I think I am very close to being on your wavelength KJW but your 'standpoint' in this demands classical confirmation as though the classical state is the reality. I can't quite get there as yet as the classical state appears to be whatever agrees with the measuring device and that state which the measuring device is intending to detect is an artificial construct or a frame of reference (if you like) from a conscious observer. :-))

[Lillie_Steins]

I think I am very close to being on your wavelength KJW but your 'standpoint' in this demands classical confirmation as though the classical state is the reality. I can't quite get there as yet as the classical state appears to be whatever agrees with the measuring device and that state which the measuring device is intending to detect is an artificial construct or a frame of reference (if you like) from a conscious observer. :-))

The point that I was making earlier is that it isn't just the devices that we design for measurement purposes that produce the appearence of wavefunction collapse. Wavefunction collapse can be regarded as having occurred whenever any process increases the entropy of the universe.

[Paul Bunyan]

There is a variant of the many-worlds interpretation known as the "many-minds interpretation" in which conscious observers play an essential but passive role in the apparent collapse of the wavefunction. I find it difficult to dismiss this interpretation as the question of why we only observe a single eigenstate does not appear to me to be fully answered by the orthogonality produced by decoherence.

This would be very close to the direction I am taking. I think at this point I am questioning whether the observers role being passive is defined by entropy.

[MannoFr]

The point that I was making earlier is that it isn't just the devices that we design for measurement purposes that produce the appearence of wavefunction collapse. Wavefunction collapse can be regarded as having occurred whenever any process increases the entropy of the universe.

I have to mull on that KJW. I am now in a forest and there are trees falling but I can't see them..../tic . I will return for enlightenment. :-))

[Slonopotam845]

This would be very close to the direction I am taking. I think at this point I am questioning whether the observers role being passive is defined by entropy.

I think the difference between the many-worlds interpretation and the many-minds interpretation is that in the many-worlds interpretation, classicalisation occurs when the quantum state becomes entangled with the measuring device, whereas in the many-minds interpretation, classicalisation occurs when the quantum state becomes entangled with the brain of the observer when the readout of the measuring device is observed (the observer becomes entangled with the measuring device).

[NeroASERCH]

I think the difference between the many-worlds interpretation and the many-minds interpretation is that in the many-worlds interpretation, classicalisation occurs when the quantum state becomes entangled with the measuring device, whereas in the many-minds interpretation, classicalisation occurs when the quantum state becomes entangled with the brain of the observer when the readout of the measuring device is observed (the observer becomes entangled with the measuring device).

Still trying to define it properly, but there may be a hybrid option.