Objective reality may not exist, European researchers say
A new experiment shows that two observers can experience divergent realities (if they go subatomic).
- In 1961, Nobel Prize-winning physicist Eugene Wigner proposed a thought experiment by which the reality of two observers can diverge by measuring a single photon.
- Researchers recently tested Wigner's thought experiment and concluded that realities can be made irreconcilable.
- Do these results put the entire scientific method at risk? Let's not get ahead of ourselves.
Objective reality cannot be known. It's the kind of statement you expect to hear from a sophomore postmodernist or nihilists after they've torched your car. Not a group of scientists.
Yet that is the result of a recent study published in the preprint journal arXiv. Basing their investigation on a famous thought experiment developed by Nobel Prize-winning physicist Eugene Wigner in 1961, the study's researchers devised a way for observers to measure a photon's state differently, despite each measurement being equally valid.
A more human Schrodinger's cat
Wigner's friend experiment re-imagines the Schrodinger's cat thought experiment in a more humane, and ultimately testable, way. Image source: Jie Qi / Flickr
Most thought experiments read like they were devised by the Joker during an extra sadistic brainstorm — it takes either a supervillain or an ethical philosopher to rig a trolley like that! While Wigner's friend experiment is certainly a more humane Schrodinger's cat, it is no less mind-bending. Here's the simple version:
Wigner's friend, a physicist, is alone inside her laboratory measuring whether a photon sports a horizontal or vertical polarization. Before she measures it, the photon exists in a state of "superposition" — that is, its polarization is both horizontal and vertical at once. After she measures it, she receives an answer. The photon's polarization is either horizontal or vertical, not both. The superposition collapses.
As far as quantum mechanics go, that's simple. But Wigner is standing outside the laboratory at the moment. He doesn't know if his friend measured a photon or what that result would be. From his outside perspective, the photon and the record remain in a state of superposition.
For Wigner, the superposition stands; for Wigner's friend, it has collapsed to a definite state. Their realities have diverged, yet both realities remain equally valid. This led Eugene Wigner to argue that a quantum measurement could not exist without a conscious observer.
"[I]t was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness," he wrote in Symmetries and Reflections. "[I]t will remain remarkable, in whatever way our future concepts may develop, that the very study of the external world led to the conclusion that the content of the consciousness is an ultimate reality."
Breaking down objective reality
No, Donny, these men are quantum physicists, there's nothing to be afraid of. Photo credit: Working Title Films
Most thought experiments remain puzzles we can only untangle with our minds. No ethics board would ever allow a team to test Schrodinger's cat. But advances in physics and technology have granted researchers the ability to test Winger's Friend. They did exactly that while doubling down.
The researchers created two laboratories that were introduced to entangled photons so that an affect on one photon must have an affect on the other. Inside each laboratory was a friend and outside were two observers named Alice and Bob (not actual people but apparatuses in the experimental setup).
The friends measured a photon in the entangled pair to determine the photon's polarized state. As with Wigner's friend, this collapsed the superposition. Then the researchers had Alice and Bob perform a nonclassical interference experiment. If the photon had chosen a state, the interference experiment would give Alice and Bob one pattern. If they hadn't, Alice and Bob would receive another pattern.
The results showed that Alice and Bob could arrive at conclusions different than their friends, while still being correct and verifiable.
"It seems that, in contrast to classical physics, measurement results cannot be considered absolute truth but must be understood relative to the observer who performed the measurement," Martin Ringbauer, a postdoctoral researcher at the University of Innsbruck, and one of the study's co-authors, told Live Science.
As the researchers point out, their experiment raises interesting questions for science, particularly in physics but also for the scientific method in general. Science relies on facts that can be established through observation and measurement, and these should not be beholden to the observer. Another observer should be able to verify them independently. But if such measurements are observer-dependent, then the scientific enterprise may have some soul searching in its future.
The researchers conclude, "This choice, however, requires us to embrace the possibility that different observers irreconcilably disagree about what happened in an experiment."
It's objectively subjective
To assuage any existential crises, it's worth noting that arXiv is a preprint journal. That means this study has not, to this writer's knowledge, been peer-reviewed as of publication. It's possible that upon review, others in the field may see omissions or derive other conclusions from the data. Debate is a part of the scientific method, too.
This can be especially true in quantum mechanics. Polls have shown that opinions vary widely among physicists on what quantum mechanics tell us about reality and what its foundational issues are. In fact, the idea of measuring superpositions and measurements proved so controversial that Albert Einstein refused to accept it — apparently, he was disturbed by the implications.
And, of course, the reality of a subatomic particle is weird and doesn't necessarily tell us how reality will work in the macro. Journalists must still adhere to facts. Scientists will still need to seek out ground truth to support their conclusions. And philosophers will still argue whether it even makes sense to talk of objective reality, whether one or many. If social media ever goes subatomic, then we should worry.
- Ancient Atomic Logic Shows Reality Is Relational, Not Objective. ›
- Neuroscience Confirms Your Subconscious Shapes Your Reality ... ›
Research in plant neurobiology shows that plants have senses, intelligence and emotions.
- The field of plant neurobiology studies the complex behavior of plants.
- Plants were found to have 15-20 senses, including many like humans.
- Some argue that plants may have awareness and intelligence, while detractors persist.
Most people think human extinction would be bad. These people aren't philosophers.
- A new opinion piece in The New York Times argues that humanity is so horrible to other forms of life that our extinction wouldn't be all that bad, morally speaking.
- The author, Dr. Todd May, is a philosopher who is known for advising the writers of The Good Place.
- The idea of human extinction is a big one, with lots of disagreement on its moral value.
Since the idea of locality is dead, space itself may not be an aloof vacuum: Something welds things together, even at great distances.
- Realists believe that there is an exactly understandable way the world is — one that describes processes independent of our intervention. Anti-realists, however, believe realism is too ambitious — too hard. They believe we pragmatically describe our interactions with nature — not truths that are independent of us.
- In nature, properties of Particle B may be depend on what we choose to measure or manipulate with Particle A, even at great distances.
- In quantum mechanics, there is no explanation for this. "It just comes out that way," says Smolin. Realists struggle with this because it would imply certain things can travel faster than light, which still seems improbable.