Each year, The Nobel Prize in Physics laureates scientists and research, bringing to light the nature of our world and making our universe more comprehensible. However, one of the craziest quantum mechanics theories is this year’s winner.
The 2022 award recognizes the work of three physicists that have challenged the status quo by seeking the secrets of the world in the tiniest particles. Aspect’s, Clauser’s, and Zeilinger’s endeavours have proven quantum mechanics are real and Einstein’s wrong (an extraordinary landmark per se). But, most importantly, they have evidenced the universe is weirder than we thought.
An unsettling science
Quantum mechanics is an insane branch of physics studying reality on an atomic and subatomic level. It is a sphere where the ‘classical laws’ of nature do not function anymore; indeed, incredible things, such as a single particle existing in different places simultaneously or a seemingly ‘telepathy’ between objects, can occur. And now, it also states our universe is not real locally, but we will try to break that down later on.
The unsettling realities quantum mechanics put forth have created major distrust and debates ever since physics became a blooming area in the 20th century. This reason renders this year’s Nobel Award remarkably meaningful, as it proves theories against all odds and traditional logic.
The quantum explanation of the universe
Understanding our system on a bitsy scale can seem over-technical and awfully conceptual —particularly if we consider our perception and experience do not help in this realm— yet a simple ‘experiment’ can provide an essential insight into the world of quantum.
Well, imagine you have two balls; one black, one white. With your eyes closed, you shuffle them and place them in two identical boxes. Following, you send one of the boxes halfway across the world while you keep the other. At this point, there is a fifty-fifty chance that your box will contain the white or the black ball. The same applies to the other box. However, the moment you open your package, you immediately know with a hundred per cent accuracy what ball is contained in the other box.
In this case, the information about the balls’ colours was always there with them. So you simply discovered which is which. But let’s imagine these are quantum balls with quantum entanglement.
Under quantum mechanics, now, you can only know the colour of the balls after opening the box. Moreover, that colour is undefined, meaning each ball is in a could-be-black could-be-white superposition state until you observe one of them. By opening a package, you force the ball to choose a colour state, consequently causing the other ball to acquire the opposite.
Suppose you change those balls to any molecular scale particle and the entanglement property to spin or momentum instead of colour. Just like that, you get a grasp on quantum mechanics and its interpretation of nature.
A battle for reality
Even the most simplistic overview of quantum’s approach to the universe is quite puzzling. How is it possible for an object to potentially have several states concurrently? Why is a particle’s state only specified the moment we study it? And, how can two linked particles ‘communicate’ faster than the speed of light?
Quantum mechanics are certainly counterintuitive. Hence, relevant voices have opposed this universe’s description since the advent of quantic studies.
Einstein was one of those voices refusing to accept such a theory as correct. For him, quantum mechanics were, practically, blasphemy, as a quantic universe ostensibly violates the principle of locality —the idea that only the immediate surroundings of an object can influence it— and the theory of relativity —stating nothing is faster than the speed of light—. Because of this, he tried to debunk the thesis by explaining it was incomplete as hidden elements not considered had to exist to justify such rarity.
Resolving the quantum entanglement enigma
Regardless of Einstein’s efforts to refute this thesis and the complexity of the matter itself, quantum physics enticed many researchers after Bohr’s and Heisenberg’s Copenhagen Interpretation collected their views on this topic.
The first approximation
Until the early ’60s, quantum mechanics weren’t more than a disputed hypothesis. Nevertheless, it all changed when John Stewart Bell developed an experiment that tested the theory of quantum mechanics in relation to Einstein’s local realism concept.
Through his experiment, he could reveal if those hidden pieces of information we were allegedly missing existed without measuring them. The test, known as Bell inequalities, has been one of the most significant contributions to the quantum world.
John F. Clauser performs the experiment
As brilliant as it is, the test was, of course, hard to perform because it required the production of atoms with entangled states and their necessary measurement and manipulation.
But here is where our first laureate appears. Clauser managed to carry out the experiment with a beam of calcium and an arc of light that produced photons. While the investigation still presented some problems that impeded denying the presence of hidden variables entirely, it proved the violation of Bell inequalities. So then, quantum physics was correct.
Alain Aspect confirms the theory
Some decades after, Aspect repeated and improved the experiment by developing a way to randomize measurement directions without any equipment movement, which helped close some loopholes.
His studies continued to reveal the same results as the previous ones; Bell inequalities were always violated in the expected amount of times according to quantum statistics. Ergo, hidden variables were again proved wrong.
The final step leading to modern quantum mechanics
By the beginning of the 21st century, quantum mechanics was an accepted truth whose study was evolving from theory to practice. Unlike the other laureates, Anton Zeilinger endeavoured his efforts towards the practical applications of quantum entanglements.
The Austrian physicist demonstrated ‘quantum teleportation’, moving a quantum state from one particle to one at a distance. As a result, he set the ground for future technologies like quantum computing.
Quantum mechanics are real. What about the universe?
Now that we have addressed the fundamentals of quantum mechanics and its history until being proven a reality, you might be wondering: what about that claim ‘the universe is not locally real’?
As aforementioned, quantum physics involve a series of bizarre, complex, and even unsettling set of rules determining the nature of the universe on an atomic level (but also as a whole). Thereupon, with the demonstration of quantum entanglement being real, we have to accept the uncomfortable fact that the universe does not work as traditionally thought.
The universe is not locally real. What is that supposed to mean? In a nutshell, our cosmos cannot be both local and real. At least one of those two properties has to be false.
Our universe cannot be real, meaning that not a single one of its properties was assigned from creation. Instead, it is in a constant superposition state (like the balls in our example) until we interact with it.
Likewise, the universe cannot be local. Being local means only the surrounding spatial and temporal neighbourhoods of a given particle can affect them. Yet, quantum proves long-distance interactions are possible.
That being said, we still don’t know which of those properties is actually false or even if both are. All we know is they can’t simultaneously be true.
A bright future
Quantum mechanics not only provide us with a new approach towards us as observers and the universe. It is indeed a large field of research that will improve our future through its applications on computers, networks and cryptography, making the technological and communicational processes of the future faster, more massive and more reliable.
I was wondering, what if there were two people looking simultaneously into the box, what would be the protocol for them to see the same color ball? Are they saying that the person makes the choice on what color ball it will be when they open the box? What leads them to make that choice?