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.

A still from the film "We Became Fragments" by Luisa Conlon , Lacy Roberts and Hanna Miller, part of the Global Oneness Project library.

Photo: Luisa Conlon , Lacy Roberts and Hanna Miller / Global Oneness Project
Sponsored by Charles Koch Foundation
  • Stories are at the heart of learning, writes Cleary Vaughan-Lee, Executive Director for the Global Oneness Project. They have always challenged us to think beyond ourselves, expanding our experience and revealing deep truths.
  • Vaughan-Lee explains 6 ways that storytelling can foster empathy and deliver powerful learning experiences.
  • Global Oneness Project is a free library of stories—containing short documentaries, photo essays, and essays—that each contain a companion lesson plan and learning activities for students so they can expand their experience of the world.
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

New simulations show how supermassive black holes form

Researchers from Japan add a new wrinkle to a popular theory and set the stage for the formation of monstrous black holes.

Snapshot of new simulation of supermassive black-hole formation

Image source: Sunmyon Chon/National Institutes Of Natural Sciences, Japan
Surprising Science
  • A new theory takes the direct-collapse theory explaining the creation of supermassive black holes around which galaxies turn ones step further.
  • The advance is made possible by a super-powerful computer, ATERUI II.
  • The new theory is the first that accounts for the likely assortment of heavy elements in early-universe gas clouds.

It seems that pretty much every galaxy we see is spinning around a supermassive black hole. When we say "supermassive," we mean BIG: Each is about 100,000 to tens of billions times the mass of our Sun. Serving as the loci around which our galaxies twirl, they're clearly important to maintaining the universal structures we see. It would be nice to know how they form. We have a pretty good idea how normally-huge-but-not-massive black holes form, but as for the supermassive larger versions, not so much. It's a supermassive missing piece of the universe puzzle.

Now, in research published in Monthly Notices of the Astronomical Society, astrophysicists at Tohoku University in Japan reveal that they may have solved the riddle, supported by new computer simulations that show how supermassive black holes come to be.

The direct collapse theories

Glowing gas and dark dust within the Large Magellanic Cloud

Image source: ESA/Hubble and NASA

The favored theory about the birth of supermassive black holes up to now has been the "direct-collapse" theory. The theory proposes a solution to a cosmic riddle: Supermassive black holes seem to have been born a mere 690 million years after the Big Bang, not nearly long enough for the standard normal black hole genesis scenario to have played out, and on such a large scale. There are two versions of the direct-collapse theory.

One version proposes that if enough gas comes together in a supermassive gravitationally bound cloud, it can eventually collapse into a black hole, which, thanks the cosmic background-radiation-free nature of the very early universe, could then quickly pull in enough matter to go supermassive in a relatively short period of time.

According to astrophysicist Shantanu Basu of Western University in London, Ontario, this would only have been possible in the first 800 million years or so of the universe. "The black holes are formed over a duration of only about 150 million years and grow rapidly during this time," Basu told Live Science in the summer of 2019. "The ones that form in the early part of the 150-million-year time window can increase their mass by a factor of 10 thousand." Basu was lead author of research published last summer in Astrophysical Journal Letters that presented computer models showing this version of direct-collapse is possible.

Another version of the theory suggests that the giant gas cloud collapses into a supermassive star first, which then collapses into a black hole, which then — presumably again thanks to the state of the early universe — sucks up enough matter to go supermassive quickly.

There's a problem with either direct-collapse theory, however, beyond its relatively narrow time window. Previous models show it working only with pristine gas clouds comprised of hydrogen and helium. Other, heavier elements — carbon and oxygen, for example — break the models, causing the giant gas cloud to break up into smaller gas clouds that eventually form separate stars, end of story. No supermassive black hole, and not even a supermassive star for the second flavor of the direct-collapse theory.

A new model

ATERUI II

Image source: NAOJ

Japan's National Astronomical Observatory has a supercomputer named "ATERUI II" that was commissioned in 2018. The Tohoku University research team, led by postdoctoral fellow Sunmyon Chon, used ATERUI II to run high-resolution, 3D, long-term simulations to verify a new version of the direct-collapse idea that makes sense even with gas clouds containing heavy elements.

Chon and his team propose that, yes, supermassive gas clouds with heavy elements do break up into smaller gas clouds that wind up forming smaller stars. However, they assert that's not the end of the story.

The scientists say that post-explosion, there remains a tremendous inward pull toward the center of the ex-cloud that drags in all those smaller stars, eventually causing them to grow into a single supermassive star, 10,000 times larger than the Sun. This is a star big enough to produce the supermassive black holes we see when it finally collapses in on itself.

"This is the first time that we have shown the formation of such a large black hole precursor in clouds enriched in heavy-elements," says Chon, adding, "We believe that the giant star thus formed will continue to grow and evolve into a giant black hole."

Modeling the behavior of an expanded number of elements within the cloud while faithfully carrying forward those models through the violent breakup of the cloud and its aftermath requires such high computational overhead that only a computer as advanced as ATERUI II could pull off.

Being able to develop a theory that takes into account, for the first time, the likely complexity of early-universe gas clouds makes the Tohoku University idea the most complete, plausible explanation of the universe's mysterious supermassive black holes. Kazuyuki Omukai, also of Tohoku University says, "Our new model is able to explain the origin of more black holes than the previous studies, and this result leads to a unified understanding of the origin of supermassive black holes."

5 charts reveal key racial inequality gaps in the US

The inequalities impact everything from education to health.

ANGELA WEISS/AFP via Getty Images
Politics & Current Affairs

America is experiencing some of its most widespread civil unrest in years following the death of George Floyd.

Keep reading Show less
Scroll down to load more…