One of the most puzzling discoveries in the last 50 years is the idea that the universe is not “locally real.” In simple terms, “real” means objects have fixed attributes that exist independently of being observed—like an apple being red whether someone is looking or not. “Local” suggests that objects are only influenced by their immediate surroundings, and nothing can travel faster than light. However, discoveries in quantum physics show these two concepts can’t both be true. Instead, the evidence suggests that objects might lack fixed properties until they’re observed and can somehow be influenced by things far away. This challenges the way we understand reality. Albert Einstein once joked about this, asking, “Do you really believe the moon isn’t there when you’re not looking at it?”
This idea seems completely against how we experience the world daily. As science fiction writer Douglas Adams might say, it’s the kind of discovery that has made many people angry and confused.
The Nobel Prize in Physics in 2022 was awarded to three scientists—John Clauser, Alain Aspect, and Anton Zeilinger—for experiments that helped prove the strange nature of quantum reality. These experiments confirmed that local realism doesn’t work in quantum physics. They showed that particles can become “entangled,” meaning their states are linked even when far apart. This entanglement defies classical ideas about how objects should behave. The work of these three scientists builds on theories first proposed by physicist John Stewart Bell in the 1960s. Bell had created a framework for testing whether the world works according to local realism or the strange rules of quantum mechanics.
For decades, ideas about quantum entanglement and non-locality were treated as more philosophy than science. From the 1940s to the 1990s, most physicists avoided the topic, dismissing it as speculative. Publishing papers on quantum foundations was difficult, and finding a job in the field was nearly impossible. Sandu Popescu, a physicist, recalls his advisor warning him not to pursue this area because it might be interesting for a few years but could leave him jobless.
Today, quantum mechanics has become one of the most exciting and influential areas of physics. It has practical applications in quantum computing, sensors, and materials science. For example, understanding entanglement has been crucial to developing quantum computers. These machines operate on principles that seem impossible according to classical physics but are made possible by quantum mechanics.
The journey to understanding quantum entanglement began with the famous “EPR paradox” proposed by Einstein, Boris Podolsky, and Nathan Rosen in 1935. They suggested that quantum mechanics was incomplete and should be replaced with a theory that restored local realism. They imagined a scenario where two particles are sent in opposite directions. If one particle’s spin is measured, the result instantly determines the spin of the other particle, even though they are far apart. This “spooky action at a distance,” as Einstein called it, seemed absurd. He believed there must be hidden variables—unknown factors influencing the particles—keeping reality local and predictable.
John Bell revisited this question in the 1960s. He realized that hidden-variable theories and quantum mechanics could lead to different experimental outcomes. This meant the two ideas could be tested in the real world. Bell created a mathematical inequality, now called “Bell’s inequality,” to determine whether local realism or quantum mechanics was correct.
The first experimental test of Bell’s ideas came in the 1970s when John Clauser, a graduate student at the time, conducted an experiment. Using simple and improvised equipment, he and his colleague Stuart Freedman measured entangled photons. Their results showed that local realism could not explain the observed behavior of particles. However, the experiment had some loopholes, such as the possibility of hidden communication between the detectors.
In the 1980s, Alain Aspect, a French physicist, improved these experiments. He used advanced techniques to eliminate some of the loopholes. His results further confirmed the predictions of quantum mechanics, making it increasingly difficult to hold on to the idea of local realism.
Anton Zeilinger, an Austrian physicist, carried this work forward in the 1990s and 2000s. He conducted experiments over much larger distances, reducing the possibility of hidden influences. Zeilinger’s team even used cosmic sources, like starlight, to ensure the independence of their measurements. These efforts confirmed the predictions of quantum mechanics with even greater precision.
The work of Clauser, Aspect, and Zeilinger has not only deepened our understanding of the universe but has also paved the way for new technologies. Their experiments showed that the strange and seemingly impossible predictions of quantum mechanics are real and can be tested. While the implications of these findings are still difficult to grasp, they remind us that the universe operates in ways far beyond our everyday intuition.
The Nobel Prize awarded to these scientists is a recognition of their groundbreaking work in challenging how we think about reality. It celebrates their persistence in asking difficult questions, even when the answers seemed too strange to believe.
