In my last post on Helgoland by Carlo Rovelli, I said that the Quantum entanglement and relational interpretation of the quantum mechanics need their own posts. This is the post on Quantum entanglement. However, this is not only about entanglement, but also about coherence.

I first heard about quantum entanglement in a talk by Sadhguru. That was on a podcast while driving to work. I heard it, it registered and what also registered was that Sadhguru said that the physicists call it entanglement, while actually it is coherence. But then I reached work and the thought remained there in my memory. When I encountered it again in Rovelli’s book, I decided to look at it properly.

Let’s start with the phenomenon of entanglement as it is defined by the physicists. For that we need to first tackle superposition. The inhabitants of the quantum world are described by waves. However, these waves are not something like waves that we see as ripples on a pond. The peaks and troughs of these waves represent the probability of a quantum property like position or energy. For example, let us take two electrons and describe them as waves. When the two waves meet, a new wave emerges. This new wave changes the probability of finding an electron at a certain place and it can affect physical properties of an atom.

We can say that the electron has two energies at the same time or the electron is likely to occur at many different places at the same time. This is the phenomenon of quantum superposition. Where two different and maybe contradictory properties can exist at the same time. In my opinion, this article at quantumatlas is the most lucid explanation of this phenomenon.

As I mentioned in the last post, the most famous example of superposition is the thought experiment of Schrodinger’s cat. The experiment is simple. In a box, there is a cat and an implement that holds poisonous gas. There is a quantum phenomenon of happening with one in two probability. If it happens, the implement activates and releases the poison and the cat dies. If it doesn’t then the cat lives.

The “psi” wave of the cat, according to quantum theory, is in a quantum superposition of “cat-alive” and “cat-dead”; and it remains so until we actually see the cat. So, the cat is in a “quantum superposition” of “cat-alive” and “cat-dead”.

This is different from saying I do not know whether the cat is alive or dead. There is a quantum interference active between the states of “cat alive” and “cat dead”. Schrodinger’s experiment is a thought experiment. However, the phenomenon of quantum superposition is not something that can be observed directly. What we can observe is the quantum interference. In Rovelli’s book he explains the observation of quantum interference in an experiment done by Anton Zeilinger.

Now let’s look at entanglement. Rovelli introduces entanglement with –

As he says, it is the strangest of all strange quantum phenomena. Imagine, two balls in quantum entanglement. These balls are in a quantum superposition of “ball-red” and “ball-blue”. When you observe any of them, you either see them in red or blue color. Now imagine that one of these balls is in Delhi and the other one is in New York.

When you observe the one in Delhi, you find that it is red. If you observe the one in New York at the same time, that will also be red. As if they can speak to each other and decide to be red at the same time. Similarly, they can be blue at the same time. However, due to their entanglement they cannot be red at one place and blue at the other at the same instant of observation.

The phenomenon of entanglement is very well explained in this article through illustrations.

As I mentioned at the start of this post, I first heard about this phenomenon in a talk by Sadhguru. You can see him speaking about this in this video.

And you can read about it here – https://innerengineering.sadhguru.org/online/blog/what-yoga-says-about-quantum-physics-sadhguru

Sadhguru says –

“Actually, they’re trying to define Yoga, but in the scientific parlance, they’re calling it as quantum entanglement. Quantum entanglement means, there is one subatomic particle here, there’s another one somewhere a million light-years away. You can’t imagine what that is, but that far away, but these two are connected. They have no explanation why, all right? The word Yoga means just this. It is just that we wouldn’t call it entanglement; there is a quantum coherence. The universe, or creation, or cosmos, is entirely coherent. Nothing here is happening unconnected. If you find coherence, suddenly, you have certain mastery over things.”

He then says that in Yoga, we call this Pragna (Prajna). And this Prajna is everywhere. It need not travel anywhere, because it is everywhere. Everywhere is the only reality, somewhere is an illusion. But right now “somewhere” is the only reality that we have. And thus “Everywhere” and “Nowhere” look like an illusion to us.

The Aitareya Upanishad says – All that exist, all phenomena cosmic and psychical, are rooted in Prajna.

“Tatpragnanetram prajnane pratisthitam prajnanetro lokah prajnanam brahman.”

Here Prajna is taken to be consciousness, the basis of all phenomena, And that consciousness is Brahman.

Rovelli shares an experience from his good friend Lee, after Lee had studied entanglement. Lee recounts that he lay on his bed for hours on end staring at the ceiling, thinking.

“He was thinking about how each atom in his body must have interacted in some distant past with so many other atoms in the universe. Every atom in his body had to be entangled with billions of atoms dispersed throughout the galaxy…. He felt a connectedness with the cosmos.”

This feeling, when it comes into your experience, is the beginning of true wisdom. And at this stage you proclaim “All is one”, “Tat tvam asi”, “Know thyself”. You know the one, you know all.

In the next post, we will take a look at the relational interpretation of the quantum mechanics and will meet a 2^nd century Philosopher from India.