Objective reality may not exist, European researchers say

A new experiment shows that two observers can experience divergent realities (if they go subatomic).

Photo credit: Georgia O'Callaghan via Getty Images
  • 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.

Yug, age 7, and Alia, age 10, both entered Let Grow's "Independence Challenge" essay contest.

Photos: Courtesy of Let Grow
Sponsored by Charles Koch Foundation
  • The coronavirus pandemic may have a silver lining: It shows how insanely resourceful kids really are.
  • Let Grow, a non-profit promoting independence as a critical part of childhood, ran an "Independence Challenge" essay contest for kids. Here are a few of the amazing essays that came in.
  • Download Let Grow's free Independence Kit with ideas for kids.
Keep reading Show less

Four philosophers who realized they were completely wrong about things

Philosophers like to present their works as if everything before it was wrong. Sometimes, they even say they have ended the need for more philosophy. So, what happens when somebody realizes they were mistaken?

Sartre and Wittgenstein realize they were mistaken. (Getty Images)
Culture & Religion

Sometimes philosophers are wrong and admitting that you could be wrong is a big part of being a real philosopher. While most philosophers make minor adjustments to their arguments to correct for mistakes, others make large shifts in their thinking. Here, we have four philosophers who went back on what they said earlier in often radical ways. 

Keep reading Show less

What should schools teach? Now is the moment to ask.

The future of learning will be different, and now is the time to lay the groundwork.

What should schools teach? Now is the moment to ask. | Caroline ...
Future of Learning
  • The coronavirus pandemic has left many at an interesting crossroads in terms of mapping out the future of their respective fields and industries. For schools, that may mean a total shift not only in how educators teach, but what they teach.
  • One important strategy moving forward, thought leader Caroline Hill says, is to push back against the idea that getting ahead is more important than getting along. "The opportunity that education has in this moment to really push students and think about what is the right way to live, how do we do it and how do we do it in a way that doesn't hurt or rob the dignity of other people?"
  • Hill also argues that now is the time for bigger swings and for removing the barriers that limit education. The online space is boundary free and provides educators with new opportunities to connect with students around the world.

Keep reading Show less

Here are 3 things white people can do right now to help #BLM

Remaining silent is being complicit.

Demonstrators pause for a moment of silence during a protest over the killing of George Floyd by a Minneapolis Police officer, in McCarren Park in the borough of Brooklyn on June 3, 2020 in New York City.

Photo by Scott Heins/Getty Images
Politics & Current Affairs
  • Protests around the world are demanding an end to police discrimination and violence against black citizens in America.
  • Author and activist Dax-Devlon Ross offers advice on how white people can help during this moment.
  • Ross's suggestions include thinking and voting locally, supporting black-owned businesses, and practicing self-reflection.
Keep reading Show less
Scroll down to load more…