Here, I’ll be talking about some questions and possible answers about Schrödinger’s thought experiment, wave function collapse, and whether consciousness causing wave function collapse is a better explanation than measurement causing the collapse.
These questions and answers refer to quantum theories, but this text is intended to be neither comprehensive nor scientific about those theories. This is a philosophical inquiry after reading “The Collapse of the Wave Function” pages 80–85 and “Does Consciousness Cause Quantum Collapse” by Kelvin McQueen. You can refer to those readings, read the articles first, and read this article to clarify some thoughts and ideas.
What is the Schrödinger thought experiment?
Schrödinger’s cat thought experiment is devised by Schrödinger to make us think about superposition in an everyday situation. It says that if we put a cat and a bomb (or a poison), with %50 chance of exploding in a box and look inside the box to see whether the cat died. We cannot know if the cat is dead or alive if we don’t look, but when we do, it can be either dead or alive, not both. From a quantum mechanical perspective, Schrödinger says, until the second that we look, the cat is in a superposition of being both dead and alive in equal part at the same time.
Schrödinger’s equation determines how the wave function of a system evolves under almost all circumstances, and it is in the heart of quantum mechanics.
Why might someone take this experiment to show that there’s a tension between our ordinary experience of the world and the predictions of quantum mechanics without the addition of a collapse postulate?
The equation implies that the majority of physical states will evolve into a superposition of a wide range of states. However, the problem is that this is not our everyday experience in the world. When we measure a particle’s position, we find a definite value, not a wave-like result, or the predictions of the Schrödinger equation. There lies the need for something else, another theory, or an equation for the time that we do the measurement, therefore comes the collapse postulate. The Copenhagen interpretation says under specific circumstances (when we observe), the Schrödinger equation does not apply, and the wave function collapses into a more definite form. So, the quantum system remains in superposition until the outside world observes it. Schrödinger proposed the cat scenario to show if the Copenhagen interpretation was accurate, then it would imply the cat to be both dead and alive at the same time. He didn’t believe this, and the thought experiment was intended to showcase its absurdity.
If our observation causes collapse, then the cat’s reality of dying or being alive depends on our looking. We experience one single concrete reality in our everyday life. This thought experiment implies that before observation, everything is in a superposition. However, it’s counterintuitive because we experience a concrete reality, which causes the tension between quantum interpretations and our everyday experience.
Why is “Consciousness triggers wave function collapse” is an improved theory rather than the traditional claim “Measurement triggers wave function collapse”?
The first problem is that measurement is ill-defined and very vague. It is too unclear to appear in a fundamental physical theory. Second, a measurement device is itself also a physical object made up of fundamental stuff, so new physical laws shouldn’t govern it. Third, measurement requires an observer, a conscious (and probably sapient) being. We expect physics to explain the universe before humans and other conscious beings existed on Earth. These are some of the measurement problems.
Some people support the view that consciousness causes collapse. They argue that consciousness is a better proposal than measurement to explain when the collapse occurs. Wigner says consciousness is what collapses the wave function. To accept this view, we must accept a specific sort of theory of consciousness, such as the Integrated Information Theory. Integrated Information Theory (IIT) says systems have different consciousness levels regarding the physical system’s integrated information. If we accept the IIT, we accept that even an atom or an electron has small levels of consciousness. This theory dissolves the problem of the necessity of an observer for quantum to collapse to occur because electrons and atoms have been in the universe for all of universe’s history.
Also, the people who believe in the Standard Model (who don’t believe in ‘consciousness collapses the wave function’) came up with different theories to resolve the measurement problem. McQueen says these theories, such as the many-worlds theory is ontologically extravagant, and that consciousness causes collapse is much more elegant and straightforward.
What are the three objections McQueen considers?
“Objection 1: The notion of ‘consciousness’ is poorly defined. The hypothesis cannot solve the measurement problem since ‘consciousness’ is as poorly defined as ‘measurement’. Accordingly, it cannot offer any new testable predictions.
Objection 2: Physical descriptions should not vary according to who the observer is. This is especially so in light of the fact that observers are relatively new to the universe — it took billions of years for the first animal to appear on Earth. This hypothesis violates that requirement.
Objection 3: The hypothesis is not consistent with physicalism, the reigning foundational assumption in philosophy. It instead requires some sort of obsolete mind-body dualism that has been refuted by philosophers.”
Describe the strongest objection and McQueen’s reply.
I take the first objection to be the strongest because there still isn’t one theory of consciousness that can fully explain the phenomenon with all the aspects that need to be considered. Each theory has its strengths and weaknesses, so basing important questions that will have implications on the nature of reality, such as what causes collapse or at what specific point particle collapse happens on a not-so-strong (not objection-proof) theory can be problematic. In his response, McQueen says, ‘consciousness causes collapse’ is a hypothesis of Integrated Information Theory. He says it makes sense to accept the theory since it can be calculated mathematically, and at some point in time in the future, we can hopefully do experiments to test it. I don’t think his reply eliminates the objection since IIT isn’t a fully formed objection-proof theory, and it’s not even one of the more accepted, leading theories of consciousness, so it still holds that consciousness isn’t more clear or precise than measurement. However, there are still other questions to answer, such as why a phenomenon such as ‘consciousness causes collapse’ would accompany the precise and beautiful Schrödinger’s equation in telling us the nature of reality. There might be even more problems that are in discussion about consciousness than measurement. I think it’s a positive aspect that there are already numerous people working on consciousness, so if ‘consciousness causes collapse’ is true, we will have a lot of ideas and theories already on the table. Also, McQueen does make a point in saying that it’s a mathematical measure, so a possible experiment’s availability makes it worthwhile. It should be interesting to see such experiments by accepting this view. Overall, I think ‘consciousness causes collapse’ is a strong hypothesis and should be taken seriously.