In my view, this is one of three main differences. Another is the discreteness of space-time we have already referred to in previous posts. And the third is this:
In classical statistical mechanics (Boltzmann) there is no sharp limit to define irreversibility. Suppose an experimenter injects a gas into a box through an opening. During injection the concentration of gas molecules will be high in a little region around the opening. But once injection ends it will decrease and after a time become about the same all over the box. The probability P of having spontaneously all gas molecules around the opening again decreases with increasing number of molecules N: when N tends to infinity, P tends to 0. Nonetheless by putting work into the system the experimenter can revert the process (“play the movie backwards”) to concentrate again the gas around the opening, and eject it from the box.
By contrast, quantum mechanics assumes irreversibility and a sharp limit for defining it, although we don’t know today where this limit lays. This is the so called Measurement Problem, which is the big challenge unsolved to date.
This problem has many implications. One of them refers to the moment when the outcome of a quantum experiment happens and a result becomes available as detection.
Consider for instance single photons being detected in a photomultiplier: The absorption of the incoming photon by an electrode called cathode results in the emission of an electron, which then is multiplied by releasing further electrons in a chain of electrodes known as dynodes; the chain ends with an electrode called anode collecting a huge number of released electrons. So, this amplification triggers a current flowing from the anode that is capable of producing a registered result, i.e.: a count one can hear as a click or see in digital counter.
In this amplification chain there is a moment T when the process cannot longer be reverted by the experimenter to restore the original quantum state of the incoming photon. This moment T marks the time when the detection takes place.
John A. Wheeler has described this moment with the famous quotation:
“No elementary quantum phenomenon is a phenomenon until it is a registered (‘observed’, ‘indelibly recorded’) phenomenon, ‘brought to a close’ by ‘an irreversible act of amplification’.”
The Measurement Problem refers to the fact that today we cannot say when and why this moment T takes place.
There are two main different Answers to this question:
The irreversible registration takes place
at the moment when some experimenter observes and becomes aware of the outcome;
somewhere in the apparatus, but the conditions defining T are related to the processes that happen in our brain when we consciously perceive a signal entering our senses.
I endorse Answer 2.
My answer is NO, and it follows from what I have previously said:
Note that you are introducing the concept of “macroscopic events” without definition.
So, when can an event be called “macroscopic”? We meet here again the Measurement Problem.
Accordingly we can answer:
The apparent predictability of “macroscopic events” is the result of the very process by which quantum experiments produce irreversibly registered outcomes that are accessible to our senses. After irreversible registration, we human experimenters are no longer capable of reproducing the original state because we can only act upon the system by means of operations within space-time: The outcome becomes a visible thing (for instance a blackening in a photographic plate or a mark printed on paper) whose trajectory is apparently predictable for us, that is we can predict it with probability near 1 (but never 1).
Quantum irreversibility has the noteworthy (but often overlooked) implication that we human experimenters cannot produce quantum superposition of “macroscopic objects” as for instance “Schrödinger cats” or “the sun dancing at 2 pm in the sky”. The “quantum esoteric” hype owes much of its success to the “Schrödinger cats”. One overlooks that such phenomena are in fact “miracles”, which can only be produced by someone acting into the system from outside space-time.
In a sense quantum irreversibility at detection is similar to the irreversibility of death: Something happens beyond our capabilities to repair.
I hope this is helpful and will be pleased providing further clarifications.