What may this year's Nobel Prizes in Physics mean?

 

What may this year's Nobel Prizes in Physics mean?

 

Who and why were they awarded?

Have you heard? The 2022 Nobel Prize in Physics was awarded jointly to Alain Aspect, John F. Clauser and Anton Zeilinger.

 

All three laureates received the prize because of their fundamental contributions to quantum mechanics, relating to experiments with entangled/coupled, photons. These experiments showed that information can be transmitted directly over infinite distances, known as quantum teleportation.

 

What is Bell's theorem?

The prize winners' experiments follow what is known as Bell's theorem. In simple terms, according to this theorem, what is attempted is to measure whether quantum mechanics approximates Newtonian mechanics, which is based on events that occur on a local scale (e.g. two balls colliding, after the collision they only affect each other) or whether, for example, the particles used in an experiment can be influenced by other particles that may be located at extremely large distances.

 

Bell's theorem argues that if certain predictions of quantum theory are correct, then our world is non-local. "Non-local" means that there are interactions between events that are far apart in space and very close together in time. What does this mean? Quite simply it means that if the quantum approximation is correct then events are connected even by signals moving at the speed of light. This theorem was proved in 1964 by John Stewart Bell and over the last few decades has been the subject of extensive analysis, debate and development by both experimental and theoretical physicists. The relevant predictions of quantum theory were first convincingly confirmed by the experiment of Aspect and his collaborators in 1982. Since then they have been confirmed many times. In the context of the predictions of Bell's theorem, the experiments prove that our world is non-local. This conclusion is very surprising, given that non-locality seems - without being 100% sure - not to be predicted by Einstein's theory ofrelativity.

 

Is quantum non-locality incompatible with Einstein's relativity?

Here is an important issue, then! Is non-locality incompatible with fundamental relativity? To attempt to answer this question one has to face a significant difficulty: What does it mean that a theory can be characterized as fundamentally relativistic? It may seem strange that such a difficulty exists for scientists today. For example, one might think that Maxwell's Einsteinian electromagnetism is a fundamentally relativistic theory, whereas Newtonian mechanics is not. Obviously, for many theories of physics it is indeed straightforward to label them as fundamentally relativistic or not. However, there is a way to show that it is not easy to precisely formulate the notion of a "fundamentally relativistic theory", and as far as theories of quantum phenomena are concerned things are not clear; no scientist today seems to know what a fundamentally relativistic theory should look like in the quantum world.

 

Conclusion

We may summarily say that it remains unclear exactly what "fundamental relativity" means or requires. Therefore, whether Bell's theorem and related experiments can be compatible with fundamental relativity remains largely an open question and no one, even after this year's Nobel Prizes in Physics, could say with certainty that non-locality is incompatible with Einsteinian relativity.