A Trade-off Between Simplicity & The Reality

In spite of being originated from medieval philosophy, the law of parsimony which famously goes as Ockham’s Razor still remains practical in the modern times of AI and the pursuit of artificial general intelligence. Ockham’s Razor asks to cut all the unnecessary things while understanding any system to reduce complexity. This idea is a part of creating efficient ML algorithms. The tool of parsimony has its limitations too and these limitations can create an objective fake picture of the reality, and can be used to twist the facts.
People most of the times miss the point of parsimony which is to make a realistic attempt to check how and why our understanding of things which we have and the real nature of things differ, how can we fill the gap between what we theorize, what we can test and what real there exists.
Context thus plays very important role in every pursuit of knowledge, even in the knowledge of the self. It is important to understand the boundary conditions of our knowledge. One should know where their beliefs (even if they are true) can be limited, can be challenged, can be difficult to prove. That is why parsimony in any pursuit of knowledge needs to be handled with utmost care while studying the real nature of things.

Medieval Idea of Ockham’s Razor For The Modern World

Craving for Simplicity

One of the key driving factors for humans is to have complete understanding of how things work. The reason behind this is to maximize the chances of survival. Now in modern times those odds have become better. The urge to understand the working of things has been evolved into improving the quality of the survival or the existence.

The key events in the quest to understand everything that is there could be summarized as follows:

  1. There is some unexpected event which causes pain, suffering, loss (it can be opposite too, like extreme favorable growth, happiness, high gains. But the human tendency is to be more concerned about uncertain losses.)

Curiosity actually emerges from the urge to control everything that can be controlled and identifying what cannot be controlled and then working towards how to control uncontrollable things by understanding them in depth.

This is how we try to assign meaning to life, our very existence.  

  1. Then we try to observe similar events associated with such experiences, record them. We try to recreate them until we have clarity on the factors which are responsible for such events. We experiment the events repeatedly so that we can have a proper theoretical understanding or a concrete reasoning behind such events.
  2. The key factor for the reasoning to be accepted as the practical one is its consistency with another unconnected or remotely connected events. There is some “universality” in that reason or that theory.

This is roughly how we try to understand the existence. If one asks why we are always on the quest of understanding the existence the answers are diverse.

The simple answer I think is that our brain prefers simplicity so that it can spend the saved energy to maximize its chances of survival. Our brain hates complexity because once the complexity is accepted the uncertainty has to be accepted and then the brain would start to invest its energy into those things which won’t even get materialized but could get materialized because of the non-zero probability.       

Our brain craves certainty of survival.

This trait of brain to prefer simplicity might not be the nature of the reality in which it exists and tries to survive but if doing so maximizes the chances of its existence then it is a pretty much the best way.

In epistemology, the philosophy – the theory of knowledge this trait is investigated in depth. We will try to see one dimension of this thought which goes popularly as the law of parsimony and even more famously as Ockham’s Razor   

William of Ockham and Ockham’s Razor

William of Ockham was an important medieval philosopher, theologian who brought the law of parsimony into the focus. Although the idea was already in existence from Aristotle.

Aristotle believed that nature always works in efficient ways possible and thus the explanation for the events in nature ought to be the efficient ones.

Although Medieval, Ockham’s razor is one crucial idea in the age of Artificial Intelligence and Machine Learning.

Ockham’s Razor emerges from his writing called “Summa Totius Logicae” exactly as:

“Pluralitas non est ponenda sine necessitate” meaning “Plurality should not be posited without necessity”.

In modern Science, philosophy, the idea “simply” goes like this:

“Do not mix unnecessary things”

OR

“All things being equal the simplest solution is the best.”

Consequences of Ockham’s Razor

The principle of parsimony (lex parsimoniae in Latin) thereby Ockham’s Razor helps us to not complicate things when we are investigating them. It is used as a thumb rule or heuristic to generate theories having better predictability. The moment we are saying that the preferences should be to ‘the simpler theory with better predictability’ is the moment when people most of the times misinterpret the Ockham’s razor. Razor implying that chopping off everything unnecessary, if not chopped would contribute to the increase in the complexity thereby compromising the predictability. We will see how Ockham’s Razor affects positively and negatively when we are trying to understand the things around us.

Good consequences:

Search for the theory of everything

Aristotle’s belief that nature always chooses the efficient route to decide the fate of anything reinforced the idea that the theories which would explain the nature are the best if they involve the least possible variables.

Einstein’s theory of relativity and the equation of energy connecting to the mass is the best example to explain this. An elegant equation with mere 1 inch length encompasses all the big secrets of the universe.

The theory of relativity is elegant in a way that it covers Newton’s understanding of motion and gravity and furthermore extends it to the understanding of the black holes where Newton’s same theory would become limited.

Quantum mechanics explains everything that atom can create. It justifies why the earlier models of atoms were perceived in those particular ways (like atom being a solid sphere, a plum pudding, a thing with nucleus at center and electrons in their orbits).

Quantum mechanics thus is the most efficient way to explain what we observed and why we interpreted those observations in a particular way. Please note that the goal is not to falsify something, prove something wrong; the goal of knowledge or science is to understand why we theorized something in wrong way and why it doesn’t align with the reality we are trying to observe and understand.

Efficient Machine Learning Models – Generalization Error

In the age of AI, the efficiency of Machine Learning Algorithms is one crucial decision maker of the investments to be made to evolve it further. The key goal of any Machine Learning algorithm is to create a mathematical equation (or layers of mathematical equations) which would understand the data provided, make sense of it and now predict the outcomes after understanding the data.

This sounds simple while establishing theoretically but the real-life data one provides ML algorithms is filled with variety of noises – unwanted, unconnected, irrelevant data points.

If the ML algorithm would try to fit the noise too, it would add too many variables in its mathematical equations. Now the model would fit each and every data point but at the same point it loses confidence to predict the outcomes because the noise is not really connected to the system one is trying to define.

That is why a complex ML algorithm fitting all the data points (R2=1) is an ideal situation – ideal meaning practically impossible because it is exposed to a very limited dataset. An ideal ML algorithm has a “generalized” idea of the data points on which it was not trained. Meaning that this ML algorithm has such an effective understanding of what is happening in the dataset with least number of equations that it is now able to understand what could happen if something is to be predicted outside of its training dataset (Q2 – algorithm’s ability to predict the unseen data – should be maximum). L1, L2 regularization techniques used in ML are example of that. Now the ML algorithm is not just interpolating proportionally the points in between, it has its own mathematical justifications to decide whether and how to interpolate aggressively or not – in order to predict the realistic outcome.

Ockham’s Razor thus proves to be important in the age of AI to select efficient algorithms, efficient algorithms ensure efficient use of power, resources thereby the investments.

Parsimony in Psychology – Morgan’s Canon

In very simple words, I would say three words to explain what this means – “Life of Pie”.

The movie Life of Pie has a moment when Pie’s father tells him that the emotions which Pie is seeing in the Tiger Richard Parker’s eyes are mere the reflection of how Pie feels the tiger would be feeling i.e., hungry in that specific case.

In animal psychology (Comparative Psychology) researches, Morgan’s Canon asks scientist to not over-attribute any human quality that humans possess to animals without any concrete basis.

“In no case is an animal activity to be interpreted in terms of higher psychological processes if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development.”

The scene from Life of Pie strongly resonates with Morgan’s canon.

There is a reason why Morgan established this idea. We humans have a tendency to see human form in everything that is not even human – this is anthropomorphism. While studying animals, these anthropomorphic tendencies would mislead each and every study because other animals and human share many common things. Unless there is no strong evidence to justify the human like intelligent behavior the simplest explanation should be selected to justify the behavior of the animal in their psychological studies.

These are some of the examples where Ockham’s razor proves to be very valuable.

Bad Consequences (limitations of Ockham’s Razor)

There is other side to simplification of things, we will now see how people misinterpret the principle of parsimony thereby Ockham’s Razor.

Universe might prefer complexity to exist

In the pursuit of the theory of everything, Einstein himself was confused that “how could God play the dices?” How can one bridge the gap that exists between the theory of relativity and the quantum mechanics. One explains the heavenly objects and the other explains what lies at the bottom of the bottom of particles which make the universe existent.

One will realize that there is more than what we are using in current theory which needs to be considered to explain the reality in a better way.

One reason why Einstein was genius of all times is because he knew that something was missing in his theory. He was not ashamed of the complexity the theory of everything may carry. Even while speaking about his elegant theory of relativity Einstein had this opinion:

Artificial General Intelligence (AGI)

Those who are actually working in the field of AI would explain this to you that how difficult it is to create an Artificial General Intelligence (AGI). Even though we have some of the greatest chat-bots, AI assistants, AI agents, they are experts in executing specific tasks only. They can immediately get biased, they can be fooled easily, bypassed easily.

The key reasons behind these shortcomings are many. The AI tools perform the best when they are designed to perform specific tasks, they lack common sense like the humans do, they lack the emotional dimension in the decision making (one of the important aspects of how humans generalize the understanding of their surrounding), they cannot directly build the bridges between their algorithms unless enough data is provided. AI doesn’t have intuition which humans have developed over the thousands of years of natural evolution.

It is also important to understand how greatly we underestimate the computation and decision-making capability of our brains and how much power it takes to replicate the same in machines. 

So, maybe complexity is prerequisite for AGI and thus the enormous number of resources that will be required to achieve it.

Human like intelligence in Animals

The story of Koko and Robin Williams could be good example to explain this. Koko – a female gorilla was trained in American Sign Language (ASL) by Francine “Penny” Patterson. Penny called this language as Gorilla Sign Language (GSL).

Penny with Koko

There is a very famous video of the meeting between the movie actor Robin Williams and Koko. Soon after the death of her gorilla friend Michael, Koko met Robin Williams and she laughed after a long time along with Robin, she played with him, she even recognized Robin from his movie cassette cover.

Robin Williams having fun with Koko

When the instructors of Koko told her about the death of Robin Williams, she expressed her grief by signaling the instructors if she could cry, her lips were trembling in grief. See the emotional depth she had just like normal humans do.

Dolphins are also one good example to demonstrate human like intelligence in animals.

This means that Ockham’s Razor, Principle of parsimony or Morgan’s canon are of no use. What is happening here? What goes missing during the oversimplification? What are we misunderstanding?    

What goes missing in simplification?

The main problem with Ockham’s razor or its any other equivalent philosophies is the convenience they bring. Just like by collecting a biased data you can actually prove anything wrong which in reality is right, in the same way people misinterpreted the principle of parsimony.

The key reason for William of Ockham to support the principle of parsimony was because he was a nominalist. “Nominalism” says that there is nothing common between anything and everything that is there in reality. Everything has its own individual nature and what we see common in many things collectively are just the ‘names’ given to them. The red which we see in blood and in rose is just the name of the color and there is nothing like red which actually exists on its own.

This means that the color which we see in things, there is no such thing as color in its absoluteness, it is just some signal our eyes generate to tell brain the difference between the light absorbed and light reflected or the temperature of the surface of the object.

So, William of Ockham posed that as everything has its own attributes individually, when you are trying to create a philosophy for a group of things, you should consider only those individual attributes which are necessary to create a theory.

(William of Ockham himself drifted away in his ideas of Parsimony and Nominalism; I will discuss that specifically in the Philosophy of Nominalism next time.)

What people still misinterpret today when they talk about Ockham’s razor is “to select the simplest explanation to things”. This is not what he meant actually.

Same is the story with Morgan’s Canon. Morgan’s main intent was to have a concrete justification when someone is explaining human-like behavior in animals. His idea was that the conclusions should be reasoning-based and not based on the observation that animals in the study had that specific type of intelligence. The idea was to observe without any preconditioning, prejudice or any impression or expectation.

I have already explained how Einstein was a genius; he was very well aware that during creating the very elegant understanding of the universe he might have missed something on the expense of simplification.

The standard mathematical model in particle physics looks like this (maybe sometime in future I will be able to appreciate and explain it to its core):

Context is everything

Now you will be able to appreciate why Ockham’s razor is a tool and not the final truth. People exploit Ockham’s Razor to demonstrate their philosophical grandeur and simplify the meaning to their favors consciously (sometimes unconsciously).

What people ignore is the purpose of the chopping unnecessary parts in any process to develop understanding, philosophy or theory. The goal was never to simplify things, the goal was to remove things which would interfere in the process of testing our hypotheses.

People most of the times miss the point of parsimony which is to make a realistic attempt to check how and why our understanding of things which we have and the real nature of things differ, how can we fill the gap between what we theorize, what we can test and what real there exists.

Context thus plays very important role in every pursuit of knowledge, even in the knowledge of the self. It is important to understand the boundary conditions of our knowledge. One should know where their beliefs (even if they are true) can be limited, can be challenged, can be difficult to prove because what we know is just a drop, what we cannot know is ocean.    

I think what people miss in simplification or parsimony is the context and context varies from situation to situation.

Scientifically, Newton’s laws of gravitation have no problem when we are talking about our solar system. In fact, they are so accurate that modern space missions still rely on these laws. There rarely is any need to use the science of black holes in most of such missions.

The context is the precision of deciding the trajectory of objects in solar system.

But, when it comes to Global Positioning System (GPS), the theory of relativity becomes important. The bending of space time due to earth’s mass and the slowing down of time for navigation satellites from it and the time adjustments for atomic clocks at these two points matters a lot. Newton’s laws cannot explain that.  

The context is how precise can the time be measured and how the difference in time can be connected to the understanding of the position of the object around the globe.

It is very easy to demonstrate how Ockham’s razor still remains important in scientific community and how scientists are aware of its limitations.

It becomes problematic when we try to understand and justify life with it.

The problem is that we get to decide the context (most of the times)

Call it a blessing because scientific community is always in the state of its own renewal because it relies on objective evidences, but it is still not immune to missing context or wishful context. (The falsified biased scientific studies published to create confusions are best example of that.)

The best example of losing context while still being scientific or unbiased is the Debates on News channels or any debate (sadly) that exists on popularity. Soon you will realize that the context of most of such debates is to entertain people, create controversies and not find the ultimate truth or facts.

In the very opening of this discussion, I had explained how our brains try to optimize processing to save energy for better tasks to guarantee better survival. The death of our own beliefs, our identity is also failure to survive. Psychological, ideological death is as equal as the actual death, maybe it is more painful than real death for almost all of us. Religion is one stream of such ideologies where people are ready to die physically just because the religious beliefs, they live for should remain alive. Most of the people are scared of mathematics not because it is too complicated, they fear math because it shows them the vulnerabilities in their process of step-wise thinking, same people can be expert dancers, master artists, master instrument players which involve rather more complicated mathematical manipulations – music in a simple way is manipulation of certain sound wave-forms. The music theory, harmony, color theory, physiological manipulation of body with the rhythm, and sound are all purely mathematical concepts. It’s just that we don’t want ourselves to remain in the states of vulnerabilities for longer times. It’s equivalent of exposing cover to our enemy thereby reducing our chances of survival.

The thing is that the tendency of nature to choose the path of least resistance gets reflected in our own nature too. Which is why simplification and Ockham’s Razor seems attractive. But at the same time, we forget that it is the same nature whose deliberate and continuous actions against the adversities made us who we are, made impossible things possible for us.

Daniel Kahneman has explained the two cognitive systems our brain uses in his book Thinking Fast and Slow.

System 1 is fast and intuitive good for repetitive tasks but bad at finding biases, errors, hostile to new and complicated scenarios.

System 2 is slow and deliberate for analytical and reasoning-based tasks but is not effective for routine tasks.

The people who exploit Ockham’s Razor (even William of Ockham himself! –  this story will show up in post on nominalism!) are oversimplifying things because the belief they have is justified through it. It will stand some limited tests but the moment it is exposed to universal tests they fail. And that is how religions, sects, faiths operate when they are blinding people from the real truths. I am not saying religion is bad, I am saying how objectivity in religion can be used to show its scientific nature and still fool the people. Same can happen in scientific communities, all of the pseudo-scientific concepts are one great examples of that.

Now you can see the problem. People want to create understanding of the surrounding not because they really want to understand it. They want to do it because it will feed the beliefs they already have and Ockham’s Razor or the principle of Parsimony is a great tool to facilitate that. In the end, it is just a tool. How it impacts the creation is solely based on the intent of the one who is using it.

That is exactly why when you are questioning something or are standing against something or supporting something ask yourself this one question:

Are you doing this for understanding the reality or to feed your own wishful picture of reality?

So, whenever you are trying to understand something make sure that your context is to really understand the thing and not expect it to be in certain thing you wish. Remember, you are the controller of the context and it is very easy to fool ourselves.

Further reading:

The Essence of Nominalism

Chasing The Hidden Nature of Reality

Bell’s Inequality and The Completeness of Quantum Mechanics

“The Nobel Prize in Physics for 2022 to Alain Aspect, John F. Clauser, Anton Zeilinger is important in the sense of how we understand the nature. The works of these three Nobel Laureates have confirmed that the fundamental things which make up the whole Universe follow the rules which are not consistent with the reality we experience”

“If you think you understand quantum mechanics, you don’t understand quantum mechanics.”

Richard Feynman

Ever since that damn apple fell off frw3om the tree on Newton’s head the world of science has exploded and expanded faster than maybe the Universe in which we are continuously questioning the nature of our existence, the nature of reality. Although if one really tries to understand how Newton worked out his ideas on the laws of motion, law of gravity, the calculus, they will know that it surely wasn’t the apple that did all the trick. (Given that “apples” have already contributed to change the course of the humanity in different ways)

Classical Mechanics

Sir Isaac Newton
The discovery of Gravity was not a coincidence

What made Newton’s work great is the predictability, structured-ness of the theories he developed. Newton described gravity as the force of attraction between each and every object in the universe. Higher the masses, closer the objects stronger will be the gravity. These theories make predictions which can be tested and then checked to be right or wrong. And for a long time, they were true. Then there came a time – the time. The time of Albert Einstein, where some people say that he proved Newton wrong. I will say Einstein found more generalized form for Newton’s theory of gravity. The ideas of Newton’s theory of gravity are a chunk of the bigger picture of Einstein’s theory of relativity. The theory of relativity considers the gravity not a force but rather curvature of the fabric of space-time. The mass of the object causes the space-time to curve around it hence causing the nearby objects to fall towards it. It’s like a trampoline where a heavy object is curving the elastic sheet around it wherein if other smaller objects are brought in this elastic sheet, they will be eventually pushed into the heavier objects. Newton thought of gravity as an attraction- a pull, whereas Einstein’s gravity pushes. Like Newton, the Einstein’s theory of general relativity makes predictions which can be tested by doing experiments and are proved to be right. Newton’s gravity could not predict the motion of planet Mercury around the Sun due to its limitations. Einstein’s theory of relativity predicted it accurately. Thereby proving it’s superiority.

Albert Einstein
Gravity is the bending of the fabric of Space-Time

The most important thing about Einstein’s theory of relativity is that it created the awareness of the fourth dimension and made it accessible to humanity in some indirect ways. Although, multiple dimensions are possible in abstract mathematics, but they were never accessible to humanity before the establishment of the theory of relativity. Einstein’s theory of relativity is still standing strong and predicting some of the wonders only universe can manifest.

But you know what, Einstein’s theory of relativity is not the generalized theory of our understanding of the universe. Einstein’s theory of relativity though fits for heavenly bodies, even to the grain of sand but it cannot explain the behavior of the subatomic particles making the atoms of the same grain of the sand. There are still some missing pieces in our understanding of the universe. Meaning that Einstein’s theory of relativity is applicable some special case of the reality we exist.    

Rise of Quantum Mechanics and the EPR Paper

Einstein’s attempt to formulate the theory of everything sets the Quantum mechanics in motion. The basic idea is that Newton’s and Einstein’s approaches were top-down approaches to understand the nature whereas the approaches of quantum mechanics are bottom up where the discussion starts from the subatomic particles and the fields responsible for the generation of the fundamental forces (Electromagnetic force, Strong force, Weak force) in nature. One must understand that gravity is still not explained by quantum mechanics. Which is what in a way was the point of concern for Einstein. The theory of relativity breaks at subatomic levels.

This is the part where the EPR paradox comes in picture.         

In order to understand the comments in the EPR Paper, one needs to understand some basic ideas in quantum mechanics.

The model of an atom has evolved greatly over time which also showcases how we improved our understanding of the universe.

John Dalton thought that matter on many divisions will end up in its smallest indivisible part called atom. Which established different elements will have their own characteristic atoms. This idea helped to establish the weight of an atom of each element. Combination of elements would give weight of the molecule made from that specific combination of atoms. With this idea one can exactly tell the molecular weight of product formed by the chemical reaction of two reactants.

J J Thomson in his experiments on Cathode Ray tube (exactly similar technology used in our old heavy box TVs) found out that if a high voltage is applied between two metal electrodes in a vacuum there is formation of a ray which gets attracted to the positively charged terminal thereby showing the negatively charged particles in this ray “The Cathode Ray”. Stronger the magnetic field stronger the cathode ray will deflect. And based on the relationship between the strength of magnetic field and the extent of deflection ray, Thomson found out that the weight of the particles in the Cathode Ray is very small compared to the weight the atoms. In this way the Dalton’s atomic model was revised to Plum Pudding. Where the electrons are scattered throughout the positively charged environment (Literally like the plum pieces randomly scattered in the pudding)

On further experimentation, Rutherford found out that there is vastly bigger space between the positively charged nucleus and the negatively charged electrons. This was a sort of weird plum pudding. The atom’s plum pudding has all the dough at center which positively charged and is the heaviest part of the atom. The plum pieces i.e., electrons are actually floating around this nucleus which are negatively charged. This devised the planetary model of an atom.

From here on now the real fun begins,

If the electrons are floating around the nucleus, how do they always remain in contact with their own nucleus. What makes them remain “attached” to their nucleus? If they are remaining attached to their own nucleus and are floating around it, after some time the tired light weight negative electron should get attracted towards the strong and dense positive nucleus, thereby becoming unstable. And this doesn’t happen in reality, otherwise nothing would exist from such atom as it will not hold itself longer. Technically, an accelerated electrically charged particle emits electromagnetic energy thereby losing its energy – getting “tired” and eventually falling into the nucleus. 

The Quantum Leap

Niels Bohr further sophisticated the model of Rutherford by assigning circular highways to the electrons around the nucleus. Each highway/freeway (autobahn!) has its speed limit which here in atomic model is the energy level. The difference between energy level of each highway is “quantized”. Meaning that there is no middle lane between each highway, no lane cutting/ lane crossing and no overtaking. The energy gap between each highway i.e., “orbit” is fixed. The change in highway is only possible when the electron gains or losses this fixed “quantized energy”. This jump of electron from on orbit to other coined the term the “Quantum Leap”.

Bohr’s idea was usable for simple atoms like hydrogen but it could not explain the behavior of heavier atoms and hence there was still something missing in the model of atom.

The Wave Particle Duality

Erwin Schrödinger formulated that the electrons don’t actually have discrete highways around the nucleus. Electrons are the particles that behave like a wave around the nucleus. This idea was inspired from the Louis de Broglie’s hypothesis that the subatomic particles like electron actually are the waves around the nucleus. Meaning that you cannot pinpoint the electron around the nucleus. The electron will be anywhere in the space around the nucleus, but it follows certain schedule/ timetable which is the famous Schrödinger Wave Equation.

The schedule of electron is always tightly packed. Electron is not that person who confirms his arrival to a party by immediately saying Yes or No. An electron is that friend in your group who will always has his plans and will ditch you at the last moment. To meet such type of an “electronic friend” i.e., the electron itself you have to study its behavior, its routine which is its waveform. The waveform will give you an idea where your electron hangs out the most. Such hangout places where you have largest chance of finding your electron are the “clouds of high probability” called the orbitals.     

This is where the real problems start to happen. You thought you knew everything about your dear “electronic friend”. The whole foundations of quantum mechanics are based on wave particle duality of subatomic particles.

Spin of an electron

Spin of an electron is actually term used to signify the angular momentum of an electron. Please note that spin of electron does establish that an electron is exactly a ball or a top which is spinning around the nucleus. Rather, spin only represents that there is some measurable angular momentum for an electron.  

Quantum measurements are never “Gentle”

The first and most important idea in quantum mechanics is that on subatomic levels the measurements disturb the state they are trying to measure.

The Heisenberg’s Uncertainty principle tells that if you go for the measurement of the spin of an electron the interaction between your measuring equipment and the electron will change its location. Same thing will happen when you go for the measurement of the position of an electron. The interaction between the equipment measuring the position will change the angular momentum of the electron.

Means, the effects we are trying to measure at such subatomic levels are so interaction sensitive that mere the interaction of measurement will disturb the state of the subatomic particle. Thus, you can either measure the momentum of an electron or position of an electron at a time.

The famous American physicist Leonard Susskind’s own words say,

“You can learn nothing about a quantum system without changing something else”

The quantum measurements are so interaction sensitive that they will change the state of the subatomic particle by merely interacting with the measuring equipment.

It’s like the measuring rotations of a ball in the air where you are physically flying with the ball with tachometer in hand in contact with the ball’s surface. The frictional interaction between tachometer and ball will either change the position or the rotation. Hence, you will only know about either the spin of ball or the position of the ball correctly at once. (I agree that it is one exhausting way to perform such measurements, but it serves the purpose here!)

Interaction during quantum measurements will change the state of the quantum particles

Einstein’s problem with the probabilistic nature of quantum mechanics

The wave nature of electron, the so called “fault” to measure the exact conditions of the subatomic particles all at once, the probabilistic nature of the quantum mechanics puzzled Einstein. Please note that the ideas discussed in quantum mechanics are not just some wild thoughts, these are legitimate mathematical proofs which are conceptually established in place. Einstein despised the idea of entanglement, which was not consistent with the reality he had already developed.

The entanglement- the bizarre child of an innocent mother

One bizarre concept born from an innocent concept is entanglement. As far as nature’s fundamental laws go- for creation of anything, something has to be invested in first place. This is called “conservation”. Law of conservation of energy says that the net energy of a system remains same, remains conserved always, it will change its forms but will always remain same in total. Conservation of mass says that one mass can change to other mass with totally different properties but the net mass of the system will always remain the same. Law of conservation of momentum says that if two objects of different momentum come in contact – collide, the total momentum before collision will be equal to the total momentum after collision.

In the same sense, angular momentum is also conserved in the natural phenomena.

So, now consider that two particles are generated from a particle with certain spin. In order to conserve the angular momentum of the system, the two particles will have exactly opposite spin of each other. This nullifying spin with the spin of the object they are created from will give the net constant spin to the system, thereby conserving the angular momentum of the system.

For any system the momentum is conserved

This type of connection between the new two particles from a system is called as the entanglement in quantum mechanics. (This may be, is the exact cinematic love that transcends all the barriers, all the dimensions in your favorite SCI-FI movies and fantasy movies!)   

God does not play dice

In quantum mechanics, when one tries to measure the state of a subatomic particle, the act of measurement gives a state of that particle, but this act of measurement for getting the information about that particle also fixes the state of another particle entangled with it.

Meaning that if you separate the two entangled particles at a distance and measure the spin of one particle then spin of another particle gets fixed at the moment of measurement. The question is that, how does the other particle get the information of the first particle being measured and its state? Einstein called this idea as “spooky action at a distance”.  

The EPR Paper

Einstein was so sure that there is something lacking in the theory of quantum mechanics that he published his idea about the incompleteness of quantum mechanics today famously known as the EPR Paper. Albert Einstein with Boris Podolsky and Nathan Rosen published the paper to explain why theory of quantum mechanics was still incomplete.

The abstract of this paper itself is intriguing:

“The EPR Paper”

Einstein debates that the reality is bound with all variables perfectly known. Hence, for a theory to be complete and to perfectly explain the reality there has to be one variable for each behavior. Hence, according to Einstein, as the quantum theory is completely based on wave function thereby becoming probabilistic (because wave function only gives the probability of measuring the information of the electron and does not pinpoint it) it is not giving the certain, definite, sure answers to the questions thrown at it. In simple words, if you ask a quantum physicist to pinpoint the electron around a nucleus, she/he won’t pinpoint the electron, instead they will tell that in this area there are high chances that you will find electron. As if, the quantum physicists have not studied the system completely, there is some unknown behavior that they haven’t identified yet which will complete the whole theory. Knowing this unknown variable will remove the tolerances in the theory, will remove the probabilistic nature of the theory.

Hence, Einstein puts the argument in two pieces:

First one attacks the lack of awareness of the all the variables in the quantum theory

The second one attacks on the reality, reality implying that the condition of having a definite state.

In short, either we don’t know completely about what is happening in quantum world or the quantum world does not have a real state.

Where the determinism and theory of relativity breaks

You have to understand the implications of the ideas put forth by Einstein and his colleagues in this paper. Einstein debated that the entangled particles when getting entangled secretly decide the state they are going to be. Hence, when one measures the information of the entangled particles, they seem to have been decided already. As if they have conspired about their states and our quantum theory is lacking to explain this conspiracy. The idea of fixing this state already established the concept of determinism. That every behavior in nature is already decided, it is only our lack of knowledge about nature which actually surprised us about the outcomes we experienced. If we have complete model of nature’s behavior we will not be surprised by the outcome, rather we will predict the outcome in advance. This was the heart of Einstein’s debate.   

One more reason for Einstein’s debate on incompleteness of quantum mechanics was his own theory of relativity. According to Einstein’s theory of relativity, nothing in the universe can travel faster than the speed of light. The clever trick quantum mechanics holds it that even after being separated at larger distance where the light will take significant time to travel from one particle to its entangled counterpart the information of the first particle being measured is instantaneously transferred to the another entangled one. If this is happening instantaneously, then the information of one particle being measured has to travel faster than light to the another entangled one. This was also one point of concern for Einstein.

The concept of locality becomes important here. According to the principle of locality, only the immediate surrounding can affect the state of an object thereby limiting the speed information lesser than the speed of light. But, in quantum mechanics the information transfer is instantaneous irrespective of the distance, meaning that the state of one object even after not being in immediate surrounding is affecting the state of its entangled counterpart. (Park this idea of “locality” for one interesting concept called Quantum Cryptography). This meant that quantum effects if are true then they are non-local. Which established the concept of “non-locality” – challenging and exposing the limits of Einstein’s theory of Relativity. That is why Einstein always argued about the incompleteness of Quantum Mechanics. There were some practical explanations to believe so.

The understanding of Einstein about the incompleteness of quantum mechanics was not just a random philosophical pursuit or some complicated thinking done in the air which was incomprehensible for comparatively dumb people of the times. His idea of reality was influenced by the famous mathematician of his time called Jon von Neumann who was obsessed with structuredness of the fundamental theories. Rather he was the one who defined the standards of a good fundamental theory.

Einstein was unsettled with the idea of the probabilistic nature of the quantum mechanics.

This is the only reason which got Einstein into formulating “The Theory of Everything”. A theory which will combine the gravity from his theory of relativity to the theory of generation of fundamental forces of nature from quantum mechanics (if proven right in his time). Even in his last moments of his life, Einstein was working on “The Theory of Everything”. Today String theory and Loop Quantum Gravity are two strongest contenders for theory of everything. Humanity’s most brilliant minds are working on these theories. The problem is that these theories are completely abstract, conceptual to date and still in incubation mode to design a measurable experiment to check and validate the predictions.

The Nobel Prize in Physics for year 2022 is actually awarded to the contributions made for the real- life experimentation done to prove the completeness of the Quantum Mechanics and its implementation in real world.       

The Nobel Pursuit- Bell’s Inequality

The EPR paper went in hibernation for years but, this actually became a reality in near future. The paper attracted the attention of one of the physicists at CERN called John Stewart Bell. Bell formulated a mathematical argument to explain the idea of hidden local variable in system. If this mathematical argument is proved to be right then this would also prove that Einstein was right all the time.

The Bell’s Paper where he established the inequality due to hidden variable

The beauty of Bell’s inequality is that that it gathers the intangible ideas and inspirations from EPR paper and probabilistic nature of quantum mechanics, wave function into a one definite, measurable and quantifiable equation. The equation given by Bell was testable in real world so that some concrete conclusions could be drawn about the completeness of quantum mechanics.

Bell developed a mathematical expression which was based on the assumption that the quantum mechanics has to be “Locally Real”. Where, Local means that the phenomena in quantum mechanics are not faster than the speed of light as explained and proven by theory of relativity; Real means that quantum mechanics is actually deterministic meaning that every measurement done in quantum mechanical system will give an exact answer, a definite value, a surety, it is only our lack of understanding of some hidden variables which cause the quantum mechanics to not be real.

Once the hidden variable/s in the quantum mechanics are identified, then theory will become consistent with the Classical Mechanics.

Smart thing about Bell’s equation is that it used the ideas of probability to show that quantum mechanics is not probabilistic.

Here is simplification of the idea explained by Bell:

We will set up an experiment where we will measure the spin of two entangled particles. You have to understand that in quantum mechanics the act of measurement itself changes the state of the quantum particle. So, when you are measuring the spin of a particle in say Z-direction, after measurement it spin value will no longer be the same as the measured value.

Now what we will do is that we will measure Z-direction component of the spin of one particle in Lab 1 and X-directional component of the spin of the another one which is entangled with the previous particle in Lab 2. Please note that the distance can be as large as possible on the condition that both labs receive undisturbed, un-interacted entangled quantum particles. The measurements will be exactly simultaneous.

So, the possible measurements we will get from the experiments where we only measure two variables are as follows:

The set of measurements when there are only two variables will be:

Here, M1, M2, M3, M4 are the measurements taken. Thus, for set of all measurements:

Now, the real game begins. According to EPR paper, if there are additional hidden variable/s in the model of quantum mechanics which we are not considering, the number of possible outcomes from the same experiment will increase. Say, if there is one hidden variable which we had not considered before while devising the Quantum theory called Q1, and now we are measuring this additional variable in the experiment then the number of possible states of entangled particles increase as follows:

When a new hidden variable is present in the system and if we measure that additional measurement as Q the number of possible combinations of measurement will increase. See below:

The set of measurements will be:

So, what will be the probability, the chance of getting Z directional spin positive and X-directional spin positive? i.e., What will be P (Z+, X+)?

Now, if there is one hidden variable and we are measuring that hidden variable then for the person who measures Z and Q the value of P (Z+,Q+) will be:

Similarly, for the person measuring X with hidden variable Q the value of P (X+,Q+) will be:

Now pay attention,

If we combine these three equations to establish the relation between them, the equation will be as follows:

Which is the Bell’s Inequality.

And is true, if we put the exact values,

In simple words, more variables driving the system, more will be the combinations of the measurements and thereby more complex the equation need to be to completely explain the system.

If there is hidden variable in the system, the number of possible combinations of measurements will be more than the system with lesser variables considered in the study. Which in turn will affect the balance of the possibilities of the events.

Now understand where does the quantum mechanics starts playing its tricks.

When we start to put the one-to-one values in this equation, we will realize what probabilistic nature can do. Due to the probabilistic nature of the quantum system, the measurements will not have a discrete value which lies on a straight line, rather it follows a sine wave, and if we substitute the values of the measurements from the sine wave function the inequality actually breaks.

The wave function in quantum mechanics actually tell what value it will have for measurement at certain angle. Which is indicated by the blue line in the graph below. The wave function only tells that what will the possibility that the spin will be +1 or the possibility that the spin will be – 1. The red line indicates that the measurements will be discrete (either up spin (+1) or down spin (-1)).  

Wave function does not give discrete values

For our example, if one makes a measurement of so-called hidden variable between Z- component and X-component i.e., along Q axis lying between 45 degrees from both Z and X axes the outcome will break the equality as follows:

The values for the Bell’s Inequality for quantum mechanical measurements is given by using the sine wave given in the graph above:

Hence, from the Wave Function in Quantum Mechanics:

Hence, for Bell’s Theorem in Quantum Mechanical System the inequality breaks as follows:

Which is not possible, indicating that Bell’s inequality does not hold true for quantum mechanics. Proving mathematically that there is no hidden variable in Quantum Mechanics. Quantum measurements are not discrete and give definite values, rather the measurements can take any value until we are measuring them, we can only give the probability of how the measurement will be.

This was a shock for those who considered reality as a very sophisticated and definite. The wave function of quantum mechanics does not follow the Bell’s Inequality. There was a strong need for devising an experiment to check and confirm what actually is true. But you must appreciate the power of mathematics and the intellectual level of human mind which can give such deep insight about the nature of reality.

John Stewart Bell
You can see that he has written the outcomes by classical way as 2 and by quantum way as 2 multiplied by square root of 2

The CHSH inequality

The first person with Nobel Prize in Physics of 2022 called Jon Clauser devised an actual experiment to check the Bell’s Theorem and to confirm whether there is any hidden variable in quantum mechanics. Jon Clauser, Michael Horne, Abner Shimony, and Richard Holt created the experiment and the CHSH inequality for the experiment from the Bell’s inequality.

The setup for experiment is as follows:

Two experimenter Alice and Bob (two important people in quantum cryptography. We will discuss about them in upcoming part) will receive a quantum particle simultaneously. The particles are entangled. Meaning that if Alice measures the Z-directional spin of her particle the spin will change in that direction so Bob again measuring the Z-directional spin of his particle which is entangled with Alice’s particle will give new and changed spin value in Z-direction thereby making the measurement meaningless.

Bell’s Test

So, what Bob will do is that he will measure the X – directional spin of his particle exactly when Alice measures the Z-directional spin of her particle. As the two particles are entangled with each other, we will know two states of the entangled quantum particles simultaneously (which seems like some type of cheating but is a pure possibility). The CHSH inequality for the system becomes as follows:

For any number of measurements, when spin of Alice’s particle in Z-direction indicates +1 then the Bob’s entangled one will have spin -1 in X-direction and vice versa. So, according the spin measurements, the maximum possible outcome of the equation is 2. When the experiment is repeated multiple times to converge to a fixed value, we get the statistical average of the measurements (remember that the wave function is probabilistic in nature, hence only statistical average of the measurements will yield a definite value for the equation)

Thus, for hidden variable in quantum mechanics,

Where the angular brackets indicate the statistical average of the measurements known as Dirac’s bracket notation.

But, from actual experiments done by John Clauser the CHSH inequality breaks. And the result is:

This proved that quantum mechanics does not follow the local realism as conventional classical mechanics do. Quantum mechanics does not have any hidden variable which are causing its probabilistic nature. Rather the reality is probabilistic instead of deterministic, predefined.

In the experiment done by John Clauser and his colleagues, they measured the polarization of entangled photons in two directions.

There was one loophole in the experiment of John Clauser. The angles of polarizers were preset or fixed before the entangled particles were sent out to observers from the source. This adds additional determinism in the experiment thereby making “Locally Real” to some extent, therefore the observations were to some extent discrete. I simple words, the experiment done by John Clauser and his colleagues proved a special case of for inconsistency of Bell’s inequality in Quantum Mechanics.

What Alain Prospect the second Nobel Laureate for Physics in 2022 did, that he closed this “loophole of locality”. Alain Prospect and his colleagues devised an experiment where it was possible to switch the detector settings after the entangled particles are released from the source. In simple words, Alain Aspect’s experiment increased the randomness of the combinations and the removed deterministic, predefined nature of measurement.     

Quantum Teleportation and Quantum Cryptography

So, now know that the quantum entanglement is real phenomena and not only mathematics but the experiments also follow the principles, it demands the value addition to the society. The third Nobel Laureate for Physics in 2022 – Anton Zeilinger used these principles for transfer of encrypted information.

It is now established that if one particle’s state is measured in a setup at that exact moment the state of the particle entangled with it gets fixed irrespective of the distance. It shows that the information of the first particle being measured is transferred with the speed faster than the speed of the light.

But there is one more catch,   

If we have to check the state of the second entangled particle to understand how the first particle behaved, we need to understand in what orientation of the equipment the first particle was measured. This information of the orientation of the equipment cannot be shared to the other end beyond the speed of light. But there is still use of this information. If only the people at both the ends measuring the entangled particles know the settings, orientation of measuring equipment, then only they can understand what the states of particle are.

If the entangled particles interact with some other particles or are intercepted by some enemy, there states will no longer remain the same. The information of the orientation of the equipment will show that.

Hence, the orientation of the equipment for measuring the state of entangled particles becomes a secret key for two observers- one of them is sender and another one is the receiver.

And this is exactly called as Quantum Cryptography. Quantum Teleportation refers to the transfer of information irrespective of the distances as the entanglement is instantaneous.

This implementation of quantum teleportation was done Anton Zeilinger and his colleagues using photons.

Alice will decide the equipment orientation while measuring the state
Bob will use the information of Alice’s equipment orientation for decryption
The one where someone tried to intercept

The name Alice and Bob- The “Power-couple of Quantum Cryptography” first appeared in a paper. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper “A Method for Obtaining Digital Signatures and Public-key Cryptosystems”.  Instead of using some boring name Machine A and Machine B they used Alice and Bob. (Some say that the secret message is Valentine’s Day Poem). The names became popular in no time and for any experiment in quantum mechanics you need to involve Alice and Bob. (Given that the love they have for each other!)

Philosophical implications of Bell’s inequality

The breaking of Bell’s Inequality shows that the quantum mechanical system has no hidden variables. Please note that the quantum mechanical systems are the most fundamental systems to date for the whole humanity’s understanding of the universe. This implies that even though the fundamental nature our reality is consistently changing, there are ways to completely understand. One can know the complete system without understanding it’s hidden variables.

The breaking of this inequality both theoretically and experimentally proves that the reality is not definite, predefined. This shows that nature is not deterministic. The idea that reality is mere superposition of infinite possibilities and the one of them becomes apparent only when you interact with them measure is really enlightening. The approach of your measuring equipment, the way you approach the things in nature is like the perspective you hold. The things will define their states their nature according to your perspective is such a humbling idea and learning from all these efforts of humanities greatest minds.   

References and Further Readings:

  1. Press release: The Nobel Prize in Physics 2022
  2. Three scientists share Nobel Prize in Physics for work in quantum mechanics
  3. Quantum Mechanics – The Theoretical Minimum by Leonard Susskind and Art Friedman
  4. The EPR Paper – Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? A. Einstein, B. Podolsky, and N. Rosen Phys. Rev. 47, 777 – Published 15 May 1935
  5. What exactly is the ‘spin’ of subatomic particles such as electrons and protons? – Scientific American
  6. The Universe Is Not Locally Real, and the Physics Nobel Prize Winners Proved It– Scientific American
  7. Is the Moon There When Nobody Looks? Reality and the Quantum Theory – N. David Mermin, Physics Today 38, 4, 38 (1985)
  8. Pioneering Quantum Physicists Win Nobel Prize in Physics – Quanta magazine
  9. Einstein’s ‘spooky action at a distance’ spotted in objects almost big enough to see – Science
  10. How Bell’s Theorem Proved ‘Spooky Action at a Distance’ Is Real – Quanta magazine
  11. Bell’s Theorem – Brilliant.org
  12. The EPR Paradox & Bell’s inequality explained simply by Arvin Ash – YouTube
  13. Local Reality and the CHSH Inequality – Qiskit
  14. The Experiment that Disproved Reality by Keystone Science – YouTube
  15. Security’s inseparable couple: Alice & Bob
  16. Poster Image of The History of the Atom – Theories and Models http://www.compoundchem.com/
  17. Images References: Alain Aspect | John F. Clauser | Anton Zeilinger | Sir Isaac Newton | Albert Einstein | John Stewart Bell