How deep is the rabbit hole?

23 min readAug 27, 2024

What defines reality? How can we be certain that what we perceive is truly real?

In exploring just how deep the rabbit hole goes, we will dive into Vedantic Philosophies, Neuroscience, and Quantum Physics, essentially unlocking the gateway to a profound journey of discovery.

**Albert Einstein (Relativity), Adi Shankara (Advaita Vedanta), Max Planck (Quantum Physics)**

Advaita Vedanta and Dvaita Vedanta are two of Hinduism's most influential philosophical schools, each offering distinct perspectives on the nature of reality, the self, and the divine. Both schools are based on the Vedas, particularly the Upanishads, but they differ significantly in their interpretation of key metaphysical concepts.

Advaita Vedanta is a non-dualistic (Advaita means “not two”) school of Vedanta philosophy. It was primarily developed and systematized by the philosopher Adi Shankaracharya (8th century CE, born in Kalady, Kerala, India — 140 km away from my hometown). The core concept of Advaita Vedanta is that Brahman (the ultimate reality or absolute) is the only reality, and everything else, including the individual self (Atman) and the world (Jagat), is ultimately an illusion (Maya).

Dvaita Vedanta (Dvaita means “dualism”) is a dualistic school of Vedanta philosophy founded by Madhvacharya (13th century CE). Unlike Advaita Vedanta, Dvaita Vedanta posits a fundamental distinction between the individual self (Atman) and the supreme being (Brahman or Vishnu).

Advaita Vedanta and Dvaita Vedanta offer two contrasting philosophical views on the nature of reality, the self, and the divine. Advaita emphasizes non-duality and the illusion of individuality, proposing that realizing one’s oneness with Brahman leads to liberation. In contrast, Dvaita maintains a dualistic approach, emphasizing the eternal distinction between the individual soul and God, with liberation achieved through devotion and surrender to a personal deity. Both philosophies have profoundly shaped Hindu thought and continue influencing spiritual and philosophical discussions today.

With this understanding in mind, let’s explore some case studies in neuroscience. This blog builds upon an article I originally wrote on Google Blogspot on September 22, 2005, under the same title — “How deep is the rabbit hole?”, delving into intriguing experiments in neuroscience and the quantum nature of reality.

Neuroscience — Interesting Case Studies

Dr. V.S. Ramachandran is a renowned Indian-American neuroscientist, best known for his pioneering research in the fields of behavioral neurology and visual psychophysics. He is currently a professor at the University of California, San Diego, and serves as the Director of the Center for Brain and Cognition. Dr. Ramachandran has made significant contributions to our understanding of the brain, particularly in areas related to phantom limb syndrome, synesthesia, body image disorders, and the nature of human consciousness.

Dr. VS Ramachandran — aka Marco Polo of Neuroscience: Tedx Talk: Embodied Brains and Disembodied Minds

Phantom Limbs refer to the sensation that an amputated or missing limb is still attached to the body and can even experience pain, itching, or other sensations. This phenomenon occurs because the brain continues to receive signals from the nerves that were once associated with the missing limb. These signals are interpreted by the brain as coming from the limb itself, leading to the sensation that the limb is still present.

Synesthesia is a neurological condition in which stimulation of one sensory pathway leads to automatic, involuntary experiences in a second sensory modality. For example, someone with synesthesia might see specific colors when they hear certain sounds or associate particular tastes with certain words.

The Angular Gyrus (AG), located at the junction of the parietal, occipital, and temporal lobes, plays a significant role in language, reasoning, mathematical cognition and number processing. Several studies have highlighted its involvement in various aspects of numerical and mathematical understanding

In the TEDx talk above, V.S. Ramachandran presents fascinating case studies on phantom limbs, or what could be termed illusory limbs (or “Maya limbs”), and draws intriguing parallels with synesthesia.

In last week’s (Aug 16, 2024) blog titled “Nature, Consciousness, and Mathematics,” I discussed how mathematics sets us apart from other species. Let’s now explore this topic from a neuroscience perspective, examining how evolution has enabled humans to excel in mathematics.

Cerebrum

The cerebrum is the largest part of the brain and is divided into two hemispheres (left and right), each controlling opposite sides of the body. It is further divided into four main lobes: frontal, parietal, temporal, and occipital lobes. Source: Teach Anatomy

Source: Cleveland Clinic — Limbic System — Amygdala

The limbic system is a group of interconnected structures located deep within the brain, often associated with emotions, behavior, and memory. Key components include the amygdala, hippocampus, hypothalamus, and thalamus.

Amygdala: Involved in processing emotions, particularly fear and pleasure responses. Feeling fear when encountering a threat, like seeing a snake or hearing a sudden loud noise. Experiencing pleasure and reward, such as when eating your favorite food.
Hippocampus: Plays a crucial role in forming new memories and connecting emotions to these memories. Remembering a happy event from your childhood, like your first day at school. Learning new information, such as remembering facts for an exam.
Hypothalamus: Regulates autonomic functions, such as hunger, thirst, temperature, and circadian rhythms; links the nervous system to the endocrine system via the pituitary gland. Feeling hungry or thirsty and initiating behaviors to satisfy these needs. Regulating body temperature, such as sweating when it’s hot or shivering when it’s cold. Regulating sleep and wakefulness by controlling the flow of information to the cortex.
Thalamus: Acts as a relay station for sensory and motor signals to the cerebral cortex; involved in consciousness and sleep. Filtering and relaying sensory information from the eyes, ears, and skin to the appropriate areas of the brain for processing.

Parietal Lobe

The parietal lobe (Primary Sensory Cortex, Superior and Inferior Parietal Lobule) of your brain plays a crucial role in how you perceive and interpret the world around you. It processes your sense of touch and integrates information from your other senses into a coherent, usable form. Additionally, the parietal lobe helps you comprehend your spatial relationship to the various stimuli your senses detect.

The Superior Parietal Lobule (SPL) is located towards the upper part of the parietal lobe, near the top of the head. It is primarily involved in integrating sensory information from different modalities to help us understand our body in space and to guide our movements.

The Inferior Parietal Lobule (IPL), located in the parietal lobe of the human brain, plays a crucial role in various cognitive functions, including sensory integration, spatial awareness, language, mathematics, and tool use. The evolution of the IPL is particularly significant when discussing the transition from Australopithecus to Homo sapiens, where it underwent substantial expansion and specialization.

Evolutionary Expansion of the Inferior Parietal Lobule (IPL)

During human evolution, the Inferior Parietal Lobule underwent a significant enlargement, estimated to have increased by about 6 to 7 times compared to earlier hominids like Australopithecus. This expansion is thought to be one of the key neuroanatomical changes that contributed to the development of advanced cognitive abilities in humans, distinguishing Homo sapiens from their ancestors and other primates.

Factors Influencing IPL Expansion:

Enhanced Cognitive Abilities: The enlargement of the IPL is linked to the evolution of higher-order cognitive functions such as language, mathematics, spatial reasoning, and social cognition. As human ancestors developed more complex behaviors, including tool use, hunting strategies, and social interactions, there was increased selective pressure for a more developed IPL.
Structural Differentiation: The expansion was not just a matter of size but also involved a differentiation of the IPL into more specialized subregions, enhancing its functionality.

Division of the Inferior Parietal Lobule

Supramarginal Gyrus (SMG): This region is involved in phonological processing and is critical for language comprehension and production. It also plays a role in empathy and emotion recognition by understanding others’ intentions and emotions.
Angular Gyrus (AG): This region is involved in multiple functions, including language, number processing, spatial cognition, memory retrieval, attention, and theory of mind (the ability to attribute mental states to oneself and others).

Role of the Angular Gyrus in Mathematics

Numerical Cognition: The Angular Gyrus is heavily involved in tasks that require numerical processing, such as simple arithmetic calculations, estimation, and comparison of quantities. It helps integrate different types of information (visual, auditory, and spatial) to facilitate numerical understanding.
Mathematical Reasoning: The AG is associated with more complex mathematical reasoning, such as problem-solving and abstract mathematical thinking. It supports understanding relationships between numbers and the manipulation of numerical concepts.
Retrieval of Arithmetic Facts: It plays a crucial role in the retrieval of arithmetic facts (e.g., addition, subtraction tables) stored in memory. This is especially important when solving mathematical problems quickly and efficiently without needing to calculate each time.
Conceptual Understanding of Numbers: The AG helps in the conceptual understanding of numbers and their relationships. It is particularly active when understanding more abstract mathematical concepts, such as algebra, geometry, and calculus.
Integration of Multimodal Information: The AG helps integrate different forms of sensory information (visual, auditory, and tactile) to aid in problem-solving and mathematical reasoning. For example, visualizing numbers, imagining spatial relationships, or understanding word problems in mathematics involves the AG.
Language and Mathematics Overlap: There is considerable overlap in the brain areas involved in language and mathematical processing. The AG plays a dual role in processing language-related tasks (such as reading and comprehension) and mathematical tasks, highlighting its importance in abstract thinking.

Both phantom limb sensations and synesthesia demonstrate the brain’s remarkable capacity for creating sensory experiences that are not directly tied to current physical reality. These phenomena provide valuable insights into how the brain processes sensory information, maintains body representations, and how neural pathways can become interconnected in unusual ways. The Angular Gyrus (AG), situated at the intersection of the parietal, occipital, and temporal lobes, is crucial for language, reasoning, mathematical cognition and number processing. From an evolutionary standpoint, the size of the Angular Gyrus (Inferior Parietal Lobule) in Homo sapiens has increased six to seven times. While vision is essential to how we perceive the world, Advaita Vedanta suggests that all perception is merely Maya (illusion).

Let’s explore this concept of vision from a neuroscience perspective, diving into a fascinating area that centers on perception, memory, and neural representation.

Consider the following experiment.

When a person is shown an apple (or any other object) and their neural activity is monitored, distinct patterns of neural activation are triggered by the visual stimulus.

Later, if the individual is asked to recall the image of the apple, similar neural patterns are likely to be reactivated. This observation indicates that the brain’s mechanisms for perception and memory rely on overlapping neural circuits. Research has shown that there is a significant overlap in the neural patterns associated with perceiving an object and recalling that object from memory. This overlap primarily occurs in sensory areas of the brain, such as the visual cortex, and in regions involved in memory, such as the hippocampus.

Stephen M Kosslyn et al. (2001) Neural foundations of imagery: Research on mental imagery, such as studies by Kosslyn et al. (2001), also supports this finding. When subjects are asked to visualize an object, the visual cortex, especially the primary visual areas (V1, V2), shows activity patterns similar to when the subjects actually see the object. This suggests that memory recall and mental imagery engage similar neural substrates as perception. Source: Nature: Neural foundations of imagery. Sept 1, 2001
Stephanie A Harrison & Frank Tong (2009) Study: A notable study by Stephen A. Harrison and Frank Tong in 2009 used fMRI to investigate whether visual memories (specifically visual short-term memory) are represented in early visual areas of the brain, such as the primary visual cortex (V1). They found that when subjects recalled visual patterns, the activation in the visual cortex was similar to the activation observed when they first viewed the patterns. This study provided strong evidence that memory recall can indeed involve reactivation of the neural patterns associated with initial perception. Source: Nature: Decoding reveals the contents of visual working memory in early visual areas February 18, 2009
Atsuko Takashima et al. (2009) Study: Another important study by Takashima and colleagues found evidence for the “neural reinstatement” hypothesis. They used fMRI to show that recalling an image (like a face or a scene) involves reinstating the activity patterns in the same sensory regions that were activated during initial viewing. This was particularly evident in the early visual cortex and the medial temporal lobe (which includes the hippocampus). Source: Journal of Neuroscience: Shift from Hippocampal to Neocortical Centered Retrieval Network with Consolidation. August 12, 2009

Yes, the neural activity associated with perceiving an object and recalling it from memory can show similar patterns. This phenomenon is supported by numerous studies (mentioned above) using neuroimaging techniques such as fMRI and EEG, which have demonstrated overlapping neural activations during perception and memory recall. This overlap is due to the brain’s mechanism of neural reinstatement, where recalling a memory involves reactivating the neural circuits that were initially engaged during perception

The most intriguing aspect of this case is that neural activity is identical whether you visually perceive an object or recall it from memory (this similarity in neural patterns even extends to remembering the object in dreams).

So, what purpose do the eyes serve? Why does neural activity remain consistent when the input is derived from two distinct sources?

The brain interprets the electromagnetic signals it receives, regardless of their source. In the experiment mentioned, the brain processes signals from the eyes in the same way it does those from the internal memory regions. It suggests that we are, in a sense, “jacked into the matrix.”

The brain processes billions of bits of information every second, yet we are only consciously aware of a few thousand of those bits. This means that the brain filters out the majority of the information, often without us even realizing it.

Does this suggest that we are incapable of perceiving things our brain decides to overlook or obscures from our awareness?

Does the brain filter information from visual input?

If the answer to the above question is yes, are we truly perceiving objective reality, or are we merely seeing what our brain wants us to see? Let’s delve deeper into this with some case studies from neuroscience.

The brain does not process and represent everything captured through visual input. Instead, it filters out a significant amount of information, focusing on what is deemed most relevant or necessary for the task at hand. This selective filtering and processing are crucial for managing the overwhelming amount of sensory information that our eyes continuously capture. The brain employs several mechanisms, such as attention, perceptual biases, and predictive coding to filter and prioritize visual information.

Key Concepts: Visual Filtering and Attention

Selective Attention: The brain uses selective attention to focus on specific aspects of the visual field while ignoring others. This mechanism allows us to concentrate on relevant stimuli (like a moving car when crossing the street) while filtering out irrelevant background details.

**Selective Attention: Ignoring the crowd to identify a known person**

Perceptual Biases: Refer to the brain’s tendency to perceive certain aspects of a visual stimulus in a particular way, often influenced by previous experiences, expectations, and context. These biases help the brain make quick decisions but can also lead to errors in perception.

Predictive Coding: The brain also employs predictive coding, where it uses prior knowledge and expectations to interpret incoming sensory information. This approach helps the brain quickly process relevant information and disregard what is considered redundant or unnecessary.

**Predictive Coding: Kanizsa Triangle illusion**

Examples: Attention in Visual Filtering

Visual Search Tasks: Imagine you’re at a busy airport looking for a friend. Despite the crowd, your attention is focused on identifying your friend’s unique features, like their face or the color of their clothing. Here, attention filters out irrelevant details (other people, advertisements, etc.) and prioritizes visual input that matches the characteristics of your friend.
Cocktail Party Effect: In a noisy environment, like a party, you can focus on a conversation with one person while ignoring other conversations happening around you. Visually, if you are looking at your friend while talking, your attention will filter out other faces and movements around you, allowing you to focus on the person you are conversing with.

Examples: Perceptual Biases in Visual Filtering

Size-Weight Illusion: If you are given two boxes that are visually identical but of different weights, your brain may perceive the lighter box as heavier if you are told it contains something heavy and the heavier box as lighter if you are told it contains something lighter. This bias is influenced by your expectations about the contents based on weight.
Face Perception: Humans are biased to see faces even in inanimate objects (like seeing a face in the front of a car or in a cloud formation). This perceptual bias, known as pareidolia, is believed to stem from the brain’s tendency to prioritize and recognize faces quickly, given their importance in social interaction and survival.
Context Effects in Perception: When reading words in a sentence, the brain uses the surrounding context to predict what words will come next, allowing for faster reading and comprehension. For instance, in the sentence “The cat chased the ___,” most people automatically fill in “mouse” due to context, even if the blank is not filled. This shows a perceptual bias towards predicting familiar and contextually appropriate outcomes.

Examples: Predictive Coding in Visual Filtering

Reading in Noisy Environments: When reading a book in a noisy café, your brain uses predictive coding to anticipate what the next word or sentence will be based on the context of what you have read so far. This helps you focus on the text even if background noise briefly distracts you, as the brain fills in gaps with predicted information.
Perceptual Filling-In: When you look at a partially obscured object, like a car partially hidden behind a wall, your brain uses previous knowledge of car shapes to “fill in” the hidden parts, allowing you to perceive the car as a whole even though you cannot see the entire object.
Visual Illusions: Predictive coding is often involved in visual illusions. For example, in the Kanizsa Triangle illusion, where a triangle appears to be formed by “missing” parts in a series of shapes, the brain predicts the presence of a triangle because it prefers a simpler, more familiar interpretation. Even though no explicit triangle is drawn, the brain “fills in” the gaps based on prior experience and the expectation of continuity.

Testing Predictive Coding: Perceptual Filling-In

Here is a test to check out the Predictive Coding: Perceptual Filling-In based on the book ‘Phantoms in the Brain” by Dr. VS Ramachandran. When a person looks directly at the center of the grid, the dark spot may become less noticeable or even disappear from perception over time.

Source: Phantoms in the Brain, by Dr. V.S Ramachandran — Perception Filling-In Test

1. Focus Your Gaze:

Hold the grid at a comfortable viewing distance from your eyes — about 12 to 18 inches away.
Close one eye. This step is crucial because binocular vision (using both eyes) might prevent the filling-in effect due to the brain’s ability to compare the input from both eyes.
With your open eye, focus your gaze on the center of the grid — but do not look directly at the dark spot. Instead, look slightly off to one side of the dark spot or directly at one of the squares adjacent to the center.
OR With your open eye, focus on the right side of the grid (assuming your right eye is closed) and slowly move the grid (or image) back and forth until the black spot vanishes.

2. Maintain a Steady Gaze:

Keep your gaze fixed on this spot without moving your eye for several seconds to a minute. This steady, unblinking gaze allows your visual system to adapt and the surrounding area of your retina to stop responding to the unchanging dark spot.
Try to keep your eye relaxed and avoid blinking too much. Blinking or moving your eye will reset the filling-in process

3. Perceptual Filling-In:

After a few seconds, you should begin to notice that the dark spot starts to fade or blend in with the surrounding grid squares. The brain, due to lack of new or varying information about the dark spot, “fills in” the dark area with the surrounding white or lighter color of the grid.
Eventually, the dark spot may seem to completely disappear, becoming indistinguishable from the grid’s background.

Why This Works

Monocular Vision: Closing one eye helps because when you look with both eyes, your brain uses slightly different images from each eye to construct depth and clarity. When using one eye, the brain relies more on pattern recognition and is more likely to “fill in” a consistent background, ignoring the dark spot.
Retinal Adaptation: The steady fixation on a single point causes certain retinal cells (photoreceptors) to become less responsive to an unchanging stimulus. This process, called retinal adaptation, makes the dark spot less perceptible over time as the brain overrides it with surrounding information.
Contextual Inference: The brain is a master at contextual inference; it fills in missing or ambiguous information based on the surrounding context, creating a smooth, coherent visual field.

Dr. V.S. Ramachandran uses this example to illustrate how the brain doesn’t always process visual information in a straightforward, literal way. Instead, it often “fills in” or interpolates information to create a coherent visual experience.

Does this imply that we are unable to perceive what our brain chooses to ignore or blinds us to?

The three types of visual filtering described above obscure the true reality from you, allowing your brain to determine what you perceive.
Doesn’t this align with the concept of Advaita Vedanta?
According to Advaita Vedanta philosophy, one should understand that nature is an illusion (‘Maya’), with Brahman being the creator of that illusion.

To explore different types of biases, take a look at my blog titled “Confirmation Bias.” This blog mainly discusses how to avoid confirmation bias, particularly in today’s world, where algorithms are constantly shaping and influencing our thought processes.

Now, let’s delve into the subatomic realm of quantum physics to uncover what nature reveals at its most fundamental level.

Quantum Physics

The branch of science that deals with the behavior of very tiny particles, like atoms and the particles inside them (such as electrons, protons, and neutrons). At these incredibly small scales, the rules that govern how things work are very different from the everyday rules we are used to.

Albert Einstein and Max Planck were two of the most significant figures in the development of quantum physics. Their contributions laid the groundwork for what would become one of the most revolutionary fields in science, fundamentally changing our understanding of the nature of light, energy, and matter.

Max Planck is often referred to as the father of quantum theory. His work on blackbody radiation and the quantization of energy set the stage for the development of quantum mechanics.
Albert Einstein is best known for his work on relativity, but he also made groundbreaking contributions to quantum mechanics. Einstein’s work on the photoelectric effect and his insights into wave-particle duality were crucial in the early development of quantum theory.

The Copenhagen interpretation of quantum physics is one of the most famous and widely taught explanations for how the quantum world works. It was developed in the 1920s by physicists Niels Bohr and Werner Heisenberg in Copenhagen, Denmark.

**Niels Bohr and Werner Heisenberg (1930s)**

Interpretation of Quantum Physics

According to Copenhagen’s view of quantum physics, a system does not occupy a definite state or location until it is observed; it exists anywhere in space, and you have a set of probabilities to find the place.
According to Roger Penrose, gravity collapses all these states into a single state, which we observe.
Parallel Universe interpretation proposes that all the probabilities exist in parallel universes, which means one possibility per universe, which constrains us to see two states in a single (this) universe.

The Solvay Conference in October 1927 where the world’s most famous physicists met to discuss the new quantum theory. Of the 29 participants, 17 were or became Nobel Prize winners.

Key Concepts of Quantum Physics

Particles Can Act Like Waves: In the quantum world, particles like electrons don’t just act like little balls. Instead, they can also behave like waves. This means they don’t have a definite position until you measure them — they exist in a sort of cloud of possibilities.
Uncertainty is Fundamental: One of the most famous ideas in quantum physics is the Heisenberg Uncertainty Principle, which says that you can’t know everything about a particle at once. For example, you can’t precisely know where an electron is and how fast it moves. This is not because of a lack of technology, but because that’s just how nature works at a quantum level.
Particles Can Be in Two Places at Once: Quantum physics suggests that particles can exist in multiple states or places at the same time, a concept known as superposition. It’s as if a cat in a box could be both dead and alive until you open the box to check — this is the famous Schrödinger’s cat thought experiment.
Things Can Be Connected Across Space (Quantum Entanglement): Particles can become “entangled,” meaning their properties are linked, even when they are far apart. If you measure one entangled particle, you instantly know something about the other, no matter how distant it is. This strange connection, which Albert Einstein called “spooky action at a distance,” has been experimentally confirmed.
Observation Changes Reality: In the quantum world, the act of measuring or observing something actually affects what happens. Before you observe a particle, it exists in all possible states simultaneously. When you observe it, it “collapses” into one specific state. This is part of what’s known as the Copenhagen Interpretation of quantum mechanics.
The Quantum World is Probabilistic, Not Deterministic: Unlike in classical physics, where outcomes are predictable if you know all the conditions, quantum physics deals with probabilities. We can calculate the likelihood of where a particle might be or what state it might be in, but only with certainty once we measure it.
Quantum Tunneling: Particles in the quantum world can do something called “tunnelling,” where they pass through barriers that they seemingly shouldn’t be able to. It’s like a ball rolling up a hill and magically appearing on the other side without ever going over it. This phenomenon is critical in technologies like semiconductors and explains some processes in nature, like nuclear fusion in stars.

Now, let us understand the Copenhagen Interpretation of Quantum Physics using the famous Schrödinger’s cat example.

**Erwin Schrödinger, Wolfgang Pauli (1930s)**

Schrödinger’s cat

To illustrate this idea, physicist Erwin Schrödinger came up with a famous thought experiment called Schrödinger’s Cat. Here’s how it goes:

1. The Setup:

Inside the sealed box, there’s a cat, a vial of poison, and a locked compartment with a breakable mechanism.
The mechanism is connected to a timer that, after a certain period, has a 50% chance of unlocking and breaking open, releasing the poison.

2. The Quantum Twist:

According to the Copenhagen interpretation, before you open the outer box to observe what’s happened, the mechanism inside is in a superposition state. It is both unlocked and broken open (releasing the poison) and still locked (keeping the poison sealed).

3. The Cat’s Situation:

Because of this superposition, the cat is also in a state of superposition. The cat is simultaneously both dead and alive — it is in two possible states at once: one where the mechanism has broken open, and the poison is released, and another where it remains sealed and safe.

4. Observation and Reality:

The moment you open the outer box and observe what happened, the superposition collapses. You force the system to “choose” one reality. Either:
The mechanism has broken open, the poison is released, and the cat is dead.
Or the mechanism remains locked, the poison is not released, and the cat is alive.

Key points from the above Example

Superposition: Until you open the outer box to check, the mechanism’s state (and thus the cat’s fate) exists in all possible states simultaneously — both locked and unlocked, both broken and intact.
Wave function Collapse: The act of opening the outer box (observing) causes the collapse of the quantum superposition. The situation resolves into a single, definite outcome: either the cat is alive or dead, but not both.
Observer Effect: The outcome isn’t determined until you observe (or measure) it. The mere act of looking inside the box changes the state from being uncertain (both possibilities existing at once) to certain (one definite outcome).

The example above may indeed sound like science fiction or even pure fiction. However, the reality is that it’s based on fact, and modern technology is grounded in these principles of quantum physics. Nature is not as it appears!

Quantum physics isn’t just a weird theory; it has practical applications. It’s the foundation of many modern technologies like lasers, MRI machines, transistors, and quantum computers. Understanding quantum physics also helps us explore deeper questions about the nature of reality, the universe, and the fundamental forces that govern it.

Reality

From neuroscience, we’ve learned about phenomena like phantom limbs, where the brain convinces you that an amputated body part still exists. Similarly, synesthesia provides a different sensory perspective, such as seeing numbers in specific colors. Visual filtering, which includes selective attention, perceptual bias, and predictive coding, creates an alternate version of reality. Meanwhile, quantum physics introduces concepts that sound utterly bizarre — such as the idea of being in Boston and Bengaluru simultaneously (quantum superposition), or the notion that reality only materializes when observed (or measured). And then there’s Einstein’s “spooky action at a distance,” which adds another layer of mystery to our understanding.

This compels us to reconsider our understanding of reality.

What is reality, truly?
Is it merely what we perceive through our eyes, or
is it a construct that our brain convinces us to accept?

I can show you the path, but you need to walk through it. — Buddha

Some of the following phrases may not directly translate into verses from the Upanishads, Bible, or Quran, but consider them as metaphors to help grasp the underlying concepts.

“One should know that nature is an illusion (‘Maya’), and Brahman is the creator of that illusion.” — Brihadaranyaka Upanishad (2.5.19), Shvetashvatara Upanishad (4.10)

“The mustard seed is larger than the kingdom of heaven.” — Bible: Matthew 13:31–32, Mark 4:30–32, Luke 13:18–19

“We were separated many thousands of kalpas ago, yet we have never truly been apart, not even for a moment.” — Chandogya Upanishad (6.8.7) Tat Tvam Asi” (That Thou Art)

“What is the life of this world but amusement and play? but verily the Home in the Hereafter,- that is life indeed, if they but knew.” — Quran: Surah Al-Ankabut (29:64)

Neuroscientist Anil Seth — Is Reality Real?

and the Journey begins… Enjoy!!!

Part 1: Nature, Consciousness and Mathematics.
Part 2: How deep is the Rabbit Hole? (This article)
Part 2.1: Confirmation Bias — Social Media Whirlpool
Part 3: Consciousness and the Origin of Self
Part 4: Consciousness, Who am I?
Part 5: Consciousness, an Emergent Property (Coming soon)

Acknowledgements

A special thanks to Dr. Titto Idicula, a US-trained neurologist based in Norway who writes on politics, culture, economy, and medicine, for his thorough review and for meticulously correcting the technical errors in the neuroscience sections of this article.