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 he was 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.

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New fossils suggest human ancestors evolved in Europe, not Africa

Experts argue the jaws of an ancient European ape reveal a key human ancestor.

Surprising Science
  • The jaw bones of an 8-million-year-old ape were discovered at Nikiti, Greece, in the '90s.
  • Researchers speculate it could be a previously unknown species and one of humanity's earliest evolutionary ancestors.
  • These fossils may change how we view the evolution of our species.

Homo sapiens have been on earth for 200,000 years — give or take a few ten-thousand-year stretches. Much of that time is shrouded in the fog of prehistory. What we do know has been pieced together by deciphering the fossil record through the principles of evolutionary theory. Yet new discoveries contain the potential to refashion that knowledge and lead scientists to new, previously unconsidered conclusions.

A set of 8-million-year-old teeth may have done just that. Researchers recently inspected the upper and lower jaw of an ancient European ape. Their conclusions suggest that humanity's forebearers may have arisen in Europe before migrating to Africa, potentially upending a scientific consensus that has stood since Darwin's day.

Rethinking humanity's origin story

The frontispiece of Thomas Huxley's Evidence as to Man's Place in Nature (1863) sketched by natural history artist Benjamin Waterhouse Hawkins. (Photo: Wikimedia Commons)

As reported in New Scientist, the 8- to 9-million-year-old hominin jaw bones were found at Nikiti, northern Greece, in the '90s. Scientists originally pegged the chompers as belonging to a member of Ouranopithecus, an genus of extinct Eurasian ape.

David Begun, an anthropologist at the University of Toronto, and his team recently reexamined the jaw bones. They argue that the original identification was incorrect. Based on the fossil's hominin-like canines and premolar roots, they identify that the ape belongs to a previously unknown proto-hominin.

The researchers hypothesize that these proto-hominins were the evolutionary ancestors of another European great ape Graecopithecus, which the same team tentatively identified as an early hominin in 2017. Graecopithecus lived in south-east Europe 7.2 million years ago. If the premise is correct, these hominins would have migrated to Africa 7 million years ago, after undergoing much of their evolutionary development in Europe.

Begun points out that south-east Europe was once occupied by the ancestors of animals like the giraffe and rhino, too. "It's widely agreed that this was the found fauna of most of what we see in Africa today," he told New Scientists. "If the antelopes and giraffes could get into Africa 7 million years ago, why not the apes?"

He recently outlined this idea at a conference of the American Association of Physical Anthropologists.

It's worth noting that Begun has made similar hypotheses before. Writing for the Journal of Human Evolution in 2002, Begun and Elmar Heizmann of the Natural history Museum of Stuttgart discussed a great ape fossil found in Germany that they argued could be the ancestor (broadly speaking) of all living great apes and humans.

"Found in Germany 20 years ago, this specimen is about 16.5 million years old, some 1.5 million years older than similar species from East Africa," Begun said in a statement then. "It suggests that the great ape and human lineage first appeared in Eurasia and not Africa."

Migrating out of Africa

In the Descent of Man, Charles Darwin proposed that hominins descended out of Africa. Considering the relatively few fossils available at the time, it is a testament to Darwin's astuteness that his hypothesis remains the leading theory.

Since Darwin's time, we have unearthed many more fossils and discovered new evidence in genetics. As such, our African-origin story has undergone many updates and revisions since 1871. Today, it has splintered into two theories: the "out of Africa" theory and the "multi-regional" theory.

The out of Africa theory suggests that the cradle of all humanity was Africa. Homo sapiens evolved exclusively and recently on that continent. At some point in prehistory, our ancestors migrated from Africa to Eurasia and replaced other subspecies of the genus Homo, such as Neanderthals. This is the dominant theory among scientists, and current evidence seems to support it best — though, say that in some circles and be prepared for a late-night debate that goes well past last call.

The multi-regional theory suggests that humans evolved in parallel across various regions. According to this model, the hominins Homo erectus left Africa to settle across Eurasia and (maybe) Australia. These disparate populations eventually evolved into modern humans thanks to a helping dollop of gene flow.

Of course, there are the broad strokes of very nuanced models, and we're leaving a lot of discussion out. There is, for example, a debate as to whether African Homo erectus fossils should be considered alongside Asian ones or should be labeled as a different subspecies, Homo ergaster.

Proponents of the out-of-Africa model aren't sure whether non-African humans descended from a single migration out of Africa or at least two major waves of migration followed by a lot of interbreeding.

Did we head east or south of Eden?

Not all anthropologists agree with Begun and his team's conclusions. As noted by New Scientist, it is possible that the Nikiti ape is not related to hominins at all. It may have evolved similar features independently, developing teeth to eat similar foods or chew in a similar manner as early hominins.

Ultimately, Nikiti ape alone doesn't offer enough evidence to upend the out of Africa model, which is supported by a more robust fossil record and DNA evidence. But additional evidence may be uncovered to lend further credence to Begun's hypothesis or lead us to yet unconsidered ideas about humanity's evolution.