Consider the following: When we see the color red, smell a pine tree, or sense anything distinctive in our surroundings. How is it that we tend to agree with one another about those observations? There are certainly arguments brought about because of disagreements in our perceptions, but in general, everyone we know would be able to identify a ‘chair’ if you asked them to point one out. One theory suggests we are all sensing the same, objective reality, but can differ in opinion because our senses are imperfect. This is what we call observer-independent reality — it doesn’t matter if you can see it, it’ll be there all the same. The other theory is that the universe doesn’t actually exist until we witness it. Our observations are inextricably linked to our tools for observing them. Observer-dependent reality. Given that these two theories are at odds with each other, how would you go about proving one over the other?
Researchers at Heriot-Watt University made a remarkable discovery back in February of 2019. They created an experimental set-up to a thought experiment that could answer the question of observer dependent or independent reality. They used the Wigner’s Friend Thought Experiment — an oversimplification of quantum states, conceived by Eugene Wigner in 1961 — to show us theoretically how two observers can accurately and truthfully record different versions of reality.
To begin — the thought experiment relies upon a singular photon, which can have two polarization directions. These polarization directions are measured by observer interference patterns. To understand the point made by the experiment, it is not actually necessary to understand what interference patterns are, what polarization is, or why exactly there can only be two. However, it is important to understand that until this polarization itself is measured, our singular photon will actually exhibit a detection pattern of both polarizations at the same time. This is called being in the superposition of the two polarizations, which might remind you of the famous Schrodinger’s cat scenario. The cat is actually both alive and dead inside the box until you look and see for yourself. Once measured, our photon is determined to be in either of the states of polarization, and exhibits the detection pattern of that singular polarization. This much is well-established in quantum physics.
The Wigner’s Friend Thought Experiment is about the addition of another independent observer — Wigner’s friend, who is also studying the same photon. One of the two observers, let’s say Wigner’s friend, records the polarization, which collapses the superposition state the photon began in (exhibiting both polarizations) into one of the two polarizations. This means that if Wigner’s friend were to look for the specific interference pattern of this photon, they would no longer see the pattern of a superposition, they would see the pattern of the polarization they measured. The other observer, Wigner, does not make the measurement and does not know the measurement his friend has recorded. If Wigner were to look for the interference pattern of the same photon without consulting his friend’s measurement, what would he see?
When first conceived, the thought experiment had two potential outcomes, and it remained that way for many years, until the team at Heriot-Watt University managed to create an experimental procedure to determine which of the two it could be. The first possibility was that Wigner would see the interference pattern of the photon in its collapsed polarization — the same way that Wigner’s measuring friend saw it. Since Wigner’s observations would be in accordance with his friend’s, this outcome would imply that there is an objective universe all observers could agree on.
The second possibility is that Wigner perceives, according to the prediction of quantum theory, the photon still in the superposition pattern, despite his friend’s measurement of the polarization. This, barring experimental instrument error, would mean that Wigner and his friend are both accurately measuring reality, but that their versions of reality are irreconcilably different. In essence, their measured reality is observer-dependent, not objective. This is the solution that quantum theory actually predicts, as counterintuitive as it may seem.
The researchers at Heriot-Watt used entangled photons to show that when a measurement of the polarization of one entangled photon is observed, the photon entangled with it (which is subject to all the phenomena of its entangled partner) can be observed by a different observer that is not communicating with the first observer. The first observer collapses the superposition of the entangled photons in their measurement, then the second observer checks for the interference pattern of the entangled photon. If the second observer sees the interference pattern of a singular polarization — reality at the quantum level should be observer-independent. If they see the interference pattern of the superposition, reality at the quantum level is observer-dependent. Their results? The first observer saw the singular polarization and the second observer saw a superposition interference pattern.
This, they believe, breaks the assumption that there is an observer-independent, or ‘objective,’ reality. Of course, there is still much research to be done, and many more labs will need to independently verify these results before they are accepted. But if their conclusion holds true, why is it important? And what does it mean for us?
The results imply some form of inescapable connection between our ability to perceive the universe, and the universe itself. What is it about our minds that connects us to our surroundings? Take a second to consider your beliefs about your own consciousness. It seems that many people believe our ‘conscious mind’ arises from the innumerable interactions between neurons constantly firing in our brains. Intuition, logic, and observation arise as emergent properties of our neural networks. It’s a compelling argument — our other internal organs are built of smaller parts that add up to functional wholes. Different tissue types, muscle, tendon, bone, etc, form a superstructure that carries the rest of our cells through space. Is it the same with consciousness?
If we were to provide the necessary nutrients, blood-flow, and heat to the brain of a recently dead person, they would not wake up. Coma patients, for instance, are provided with the necessary biological components that they need for cerebral functioning — yet many are unable to wake up, even with functional neurons. Our digital networks and supercomputers process and interact with themselves and each other faster than the neurons in the human brain, yet these computers do not display the intellectual capacity of the human mind. Given how little we currently understand about the functional biology of the brain (check out this link to see how far away we currently are), it would be difficult to positively conclude that the matter in the brain is all there is. The truth is we do not know where consciousness comes from.
The presence of supra-biological phenomena that are somehow fundamental in our display of consciousness is far from a foregone conclusion, and readers should form their own beliefs on the nature of consciousness. However, the question remains — if reality is truly dependent on an observer to witness it, how does that change your beliefs on the nature of your own observations? How would it change your belief about where consciousness, the ability to think through decisions and process those observations, originates from?
The concept of a ‘soul’ or a ‘spirit’ sounds silly from a materialist perspective. There are, as of yet, no studies to conduct or measurements to be taken that can prove anything about the existence of some such piece of our being. Modernists similarly agree with the materialists that just because ancient cultures and texts claim there are extra-sensory beings or parts of us, it is because these stories were created (inadequately, they might add) to explain the complex natural phenomena our ancestors witnessed. To many, our scientific pursuits provide a much more accurate representation of the world we live in. The power of materialist philosophy is all around you, making your life easier at every turn. Do you like your car? Your refrigerator? Your cell phone? These were brought to you by scientists and engineers that worked under the assumptions that there were fundamental laws for all the matter in it. The successes that technology has brought reinforce the authority with which we treat materialist and modernist arguments.
The study from Heriot-Watt University counteracts some of that momentum — it brings up questions about the nature of observation itself. It shows us that there is something entangling our perceptions with the world we perceive. It ends the narrative that there is an objective universe, separate from humanity’s observations, that we can study without interference.
An end to the separation of humans from their environment creates possibilities about future narratives. What does it mean that our senses irreversibly alter phenomena they sense just by sensing them? What is it about our brain, our body, our senses, our language, that allows us to make observations? And why can they be, at least at the quantum level, irreconcilably different?
Keep in mind, however, that just because our quantum realities might be irreconcilably observer-dependent, human-scale reality is not subject to the same uncertainty. In fact, for this experiment to work with a baseball-sized object substituted for the photon, the researchers would need an experimental test chamber the size of the known universe and more time than has ever passed in the history of the universe to conduct it. You, for all intents and purposes, see the baseball the same way any other observer sees it.
Great expectations are placed on quantum mechanics in the hopes that by observing the smallest and most fundamental constructs of the universe we will be able to properly understand our scaled-up reality. There is still a very long road ahead for physicists to travel, but they continue to raise important and interesting philosophical questions about our place in reality. If actual reality is entangled with or constructed by our senses, what does that mean about collective human experiences? And where the hell does consciousness actually come from?
The Study: https://arxiv.org/pdf/1902.05080.pdf
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