The Action Lab - Cloud Chambers and the Mott Problem

This starts at both ends of the spectrum: the phenomenon and the theory. See The wave mechanics of ∝-Ray tracks by Nevill Francis Mott:

The wave mechanics unaided ought to be able to predict the possible results of any observation that we could make on a system, without invoking, until the moment at which the observation is made, the classical particle-like properties of the electrons or α-particles forming that system. If we consider the ∝-ray alone as the system under consideration, then the gas of the Wilson chamber must be considered as the means by which we observe the particle; so in this case we must consider the ∝-ray as α-particle as soon as it is outside the nucleus, because that is the moment at which the observation is made. If, however, we consider the α-particle and the gas together as one system, then it is ionised atoms that we observe; interpreting the wave function should give us simply the probability that such and such an atom is ionised. Until this final interpretation is made, no mention should be made of the ∝-ray being a particle at all. The difficulty that we have in picturing how it is that a spherical wave can produce a straight track arises from our tendency to picture the wave as existing in ordinary three dimensional space, whereas we are really dealing with wave functions in the multi-space formed by the co-ordinates both of the α-particle and of every atom in the Wilson chamber. See Assumptions of Physics - Reading the Book.

In between these lies the experiment, which is what you need to do in order to create the necessary conditions under which the phenomenon is observed. It turns out they're quite specific: you need a super-saturated vapour, and it needs to be distributed fairly uniformly through the space where you expect to the radiation to pass. See the Wikipedia entry for Wilson chamber:

 A cloud chamber consists of a sealed environment containing a supersaturated vapor of water or alcohol. An energetic charged particle (for example, an alpha or beta particle) interacts with the gaseous mixture by knocking electrons off gas molecules via electrostatic forces during collisions, resulting in a trail of ionized gas particles. The resulting ions act as condensation centers around which a mist-like trail of small droplets form if the gas mixture is at the point of condensation. These droplets are visible as a "cloud" track that persists for several seconds while the droplets fall through the vapor.

 

These same conditions also produce other phenomena:

He also did another video related to this, about coupled oscillators and superposition of modes. This is an analogue of what is supposed to be happening in the wave-function of the phase space of the whole system in the cloud chamber.

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You can do it without dry-ice, but you still need a freezer:

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A few weeks ago The Action Lab commented on Mithuna's video: 

This is what he wrote:

In your quantum computer example, a true "measurement" isn't made until the readout stage. So a quantum computer doesn't disagree with the Copenhagen interpretation. However, I agree with you that there should be more focus on the fact that the measurement problem is unsolved. The MWI doesn't solve the measurement problem because the universe still needs to "know" when to split. Also, Bohmian mechanics has recently been shown to contradict experimental evidence (See Nature's "Energy–speed relationship of quantum particles challenges Bohmian mechanics" published this year). I personally like Henry Stapp's Quantum Interactive Dualism interpretation. Apparatuses and environments can become entangled and decohere but that’s not a true “selection” of a single outcome until the result is brought into awareness. It is more metaphysical, but I feel this is the right direction. As you clearly showed, the measurement problem cannot be solved unless there is some entity that is not part of the entangled system that can break "Von-Neuman's chain."

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