Why John Stewart Bell has haunted quantum mechanics for decades

Some people think they have a poltergeist in their ceiling, others say they have ghosts on dark nights – I have John Stewart Bell. The physicist’s research and his enormous heritage have been haunted me for years.

I assume I should not be surprised. Do you all think about how much of what we experience, like reality, is actually objective, unequivocally real? I must, or I could not write about the nature of space and time, and the intrigate goongs-on in Quantum Realm. Bell also loved to consider things and his work changed forever how we understand them.

He was born in Belfast in 1928 and was in any case an unusually curious and bright child. He locked in early physics and landed his first concert as a laboratory technician when he was 16 years old. He was trained in both theoretical and experimental physics and built much of his career in the world of particle accelerators, where he worked with calculations so complex that we super -compaulr. But what really kept Bell up at night were the cracks he could see in the basis of quantum theory.

Today this is an established physics field and many of its athletes have been shown on the sides of New scientist – Modern physics is not unfriendly to those who ask questions that sit at the border with physics, mathematics and philosophy. But when Bell came up as a researcher, physicists were still taken by the debate between quantum theory’s first waves – people like Niels Bohr and Albert Einstein – and either consider them resident or thought it was philosophy rather than physics.

So Bell only worked on them after hours, almost like a hobby. That changed in 1963, when he and his wife, also a skilled physicist, took a Sabbath day from their accelerator work, and Bell spent that time to parlay his hobby for a few sperm cities. Although they were received with fanfare and we are far overlooked for years, their meaning cannot be exaggerated.

Bell took a line of this philosophical question and made it something that could be investigated in a laboratory. That in the middle of the idea of ​​”hidden variables” in quantum mechanics.

When it was developed by Bohr and his colleagues in the 1920s and 30s, quantum mechanics are no friend of specific or determinism. Notorious you can say very little of definitely about a Quantum Objen Ultil, you interact with it. You can predict what properties it may have when measuring, but only likely. For example, you may know that an electron has a 98 per day. A hundred chance of having a specific energy when you measure it, and one 2 per. A hundred chance of having a different energy, but which it will news is completely random.

How to charge nature what energy randomly earns up to you? One explanation is that it is actually not coincidence for games here, but that some speeds – some variables – are hidden from scientists. If they could just determine what these hidden variable is, physicists could bring absolute predictability to quantum theory.

Bell devised a test that would eliminate a large cut of hidden-variable theories from competition to compensation or at least change quantum theory. This test requires two experiments, typically called Alice and Bob. The Peers of Start -Ups party is repeatedly produced, then a party in each peer smell for Alice, while its party species goes to Bob at a distant laboratory. After receiving their particles, Alice and Bob each select to measure a particular feature. For example, Alice can measure her particle spin.

The competent also makes Bob measurements and chooses how to do them, but Alice and Bob do not communicate the experience. At the end, they connect their respective data to an equation that Bell derived in 1964. This “inequality” equation tests the data to correct Alice’s and Bob’s measurements. Even without quantum effects, some contexts may arise in luck. But Bell determined a correlation level that shows that something else is going on: the particles are correct in a way found only in quantum physics and cannot exist if there is a local hidden variable.

In this way, Bell’s tests fees more than diagnosing quantum theory as a better description of our reality than these deterministic, hidden-variable theories-it also zeros on the unequal feature of “non-locality” as something that seems to be a bisarr by our reality. Non-locality means that quantum objects can maintain a connection and that their behavior can remain inerticublicch corrected, look out how far they are. Einstein was a huge critical of this, partly it was uncomfortably close to immediate communication between objects, which is strictly prohibited by his theory of special relativity.

Bell was something of an acolyte of Einsteins, but the vagaries of physical reality led to him ultimately wrong from his idol. His test tilted a firm finger against our world that was quantum, something that scientists still struggle with today, espetili when it comes to the seemingly unbreakable gap between quantum theory and our best understanding of gravity as developed by Einstein.

I couldn’t find any mention of Bell that actually worked with experimentation implementations of his test himself, and it turned out to be technologically difficult. While the first such experiment was completed in 1972, until 2015, it took a test free of LOPHoles-as strict as possible to put the last stitch in the coffin of local hidden-variable theories. By 2022, physicists Alain Aspect, John F. Clauser and Anton Zeilinger were jointly awarded the Nobel Prize in physics in their decades of working with this experience.

So why do I still see John Stewart Bell everywhere I turn? Have I been exposed to a quantum sweat?

The short answer is that his work and all the experience that tested it opened almost as many questions about quantum physics and the nature of the physical reality to answer. Although many physicists agree that our world is simple to non-room, some, for example, still try to find that the physical mechanism underlies non-locality. Others are working to develop new hidden-variable theories that cannot stemmet by Bell’s testing. Even others, others carefully reveal any and all mathematical tar bells made in his papers of the 1960s. All of them seem to believe that finding a new angle on Bell’s work, or some overlooked entry within it, may be a skeleton key to push interpretations of quantum theory beyond its current state and maybe even construct an evyer theory about everything.

The Rippel Puits from Bell’s work are everywhere in quantum physics. In fact, we are better at the start -Up -party by just trying to do bell tests over the past 50 years. But that’s just the start. A few weeks ago I spent plenty of time talking to physicists who found a way to take advantage of Bell’s work quantity test for the free will can be partial, ie. Where our freedom of choice can be limited cosmically in some cases, but not others. Then I came on the phone with another team of researchers, presumably to discuss gravity and nature of space and time, but ended up talking about Bell once again. These physicists we were inspired by his approach and wanted to test similar to his, but for gravitational traits of reality rather than quantum practice.

This too, I am part of why I can escape Bell – his ability to transform philosophically from into concrete tests of reality reflects the pace of the core of physics. The promise of physics is that it can help us to chip away by the world’s most confidential mysteries through experiment, and Bell’s test is an incredibly elegant embodiment of this promise.

If I have to be a lot of something, I honestly couldn’t ask for a better ghost.