The Marvelous Ability of Your Brain to Comprehend Space and Time

Sam episodes #4

Physics and our brains share the common goal of unraveling the secrets of the universe. However, at times, physics can clash with our ingrained notions of reality, such as the tangible existence of space and time. How do we ascertain the truth? Are time and space truly objective entities or are they merely figments of human imagination?

The history of physics is rife with surprising revelations that have shaken the very foundations of our understanding. And now, we seem to be on the brink of yet another mind-boggling breakthrough that could turn our worldview upside down.

Physicists are daring to entertain the idea that our fundamental comprehension of space and time may be flawed.

Imagine that!

It’s the kind of realization that could make your head spin, and it has the potential to shift the course of human understanding forever.

How can we buckle up for such a monumental shift in our understanding of reality?

Our understanding of space and time has undergone a transformation throughout history. Newton was all about the “Absolute” space and time, but that concept was challenged by the likes of philosophers Leibnitz and Descartes, who argued that space and time were relational.

Immanuel Kant even went a step further, suggesting that space and time were constructs of the mind rather than tangible entities.

And then came Einstein, who turned everything on its head, viewing space and time as mere concepts created by human intelligence to connect experiences. (Remember relativity?)

It is important to clarify that Einstein did not suggest that the external world is not real. He held the belief that the universe exists independently of our existence, but that the space and time that we observe are conceptualized in our brains.

Hmmm, we don’t just believe Einstein because he’s Einstein. Whether space and time are absolute and fundamental or relational and conceptual, the question remains.

These were the musings in my head when Sameera in her usual curious demeanor asked, “Have you ever wondered how instinctively you can tell the distance you’ve to reach to grab that cup of coffee?”

We were taking a break in a coffee shop during the evening.

“And not just that, you are able to discern the distance ‘I’ need to reach for my own cup. It’s fascinating, isn’t it, to ponder how our minds perform these calculations?” She added.

It is.

To be spatially capable organisms, we need our brains to do two things. Tell us —

1) Where things are in relation to us (allocentric modeling), and

2) Where everything is in relation to each other in space (egocentric modeling).

“In order to traverse our surroundings, it appears that our brains create a mental depiction of the environment,” she said.

“This process is commonly referred to as the ‘cognitive map’,” I chimed in.

In 1971, two neuroscientists named John O’Keefe and Jonothon Dostrovsky made a groundbreaking discovery while observing the brain activity of rats as they explored their surroundings.

They noticed that a specific neuron in a particular area of the rat’s hippocampus would become highly active every time the rat entered a certain region. As the rat moved to a different region, a different neuron would activate and so on.

These neurons were later identified as “place cells,” which some researchers believe to be a representation of our internal map.

In a given environment, each place-cell corresponds to a specific location, and these neurons remain fixed on those locations until the rat enters a new environment.

However, the question remains: how do these cells know where the rat is in the environment?

In 2005, Edvard and May-Britt Moser discovered a group of neurons located adjacent to the hippocampus, in an area known as the entorhinal cortex. These neurons exhibit similar behavior to place cells, firing when an experimental rat traverses a specific location in its physical environment.

However, unlike place cells, a single grid cell fires when the rat enters several other locations equidistant from each other, creating a hexagonal grid that spans the entire current environment.

These grid cells essentially divide the current space into multiple grids of different orientations and scales, with each grid tile being represented by an individual grid cell. Although each new environment is tiled differently, the grid cells provide a fixed scale, like a rigid ruler, that offers metric information at varying resolutions.

“Imagine, as you walk across a room, specific neurons in your brain’s entorhinal cortex fire at different intervals. One neuron might fire every meter, while another fires every 5 meters, and yet another fire every 10 meters. These firing patterns create a unique map of your surroundings, as each location in the space activates a distinct set of “firing grid cells,” which then trigger the activation of specific place cells”, I explained, “in other words, your brain creates a personalized cognitive map of the environment based on the firing patterns of different neurons.”

“But how do these firing grid cells stimulate the place cell?” She asked.

“One perspective is that the brain performs an inverse Fourier transform, where a combination of signals from these various grid cells come together to stimulate specific place cells in a localized manner,” I said. “We are not sure yet. The combination of grid cells and place cells appears to be a crucial component of the cognitive mechanism underlying our perception and understanding of the surrounding physical environment.”

“It appears that the mechanism involves the use of a coordinate grid, which raises the question of whether it represents a Newtonian view of space — one where the coordinates are fixed to the current environment, regardless of our location within it, and independent of the objects and elements within that environment,” she inquired, “this makes space feel absolute rather than relational.”

“You may recall that in the relational view, space is conceptualized as a network of distance relationships between objects, which is not necessarily reflected in the function of grid cells. However, our spatial processing capabilities are far more complex and multifaceted than this, with grid cells representing just one aspect of this intricate cognitive machinery,” I explained.

During our discussion, we explored the complex mechanisms behind our spatial cognition. It became apparent that our understanding of space is not only influenced by absolute measures, but also by contextual factors. Our cognitive mapping of space involves both allocentric and egocentric processes.

While allocentric processing constructs an absolute and objective model of space, egocentric processing contextualizes our understanding of the surrounding space in relation to ourselves. This contextualization involves using depth perception to construct the coordinate grid and our internal sense of velocity and direction of motion to update our position on the grid.

By utilizing these relational distance measures, we are able to build and update our cognitive mapping of space. This allows us to form a sense of space that is not centered on ourselves or any particular object, but rather an objective understanding of the environment around us.

Our hippocampus and entorhinal systems appear to be wired to represent space in this manner, which may explain why both Isaac Newton and many modern-day individuals have developed an intuition of space as an absolute entity that is independent of its contents.

As we began our walk back to my home office Sam began to slowly disappear. It was as if she was here one moment, and then suddenly, she wasn’t. But her voice lingered a little longer before she was all gone.

“I’m not saying that space is not absolute. The truth is, we don’t have concrete evidence to prove whether the universe exists in the way it does independently of our observations,” I explained.

But she wasn’t there.

No matter how many times it happens, the way in which Sam disappears from my sight still manages to break my heart as if it were the very first time. My brain struggles to accept the fact that she is not real.

But what is real, anyway?

As we had just discussed, space can be merely conceptual. Something our brain creates for us to navigate through the world.

So can be time, but that’s a story for another time.

Sam isn’t real. But she is as real as anyone else is, to me.

If it is true that without my existence, Sam ceases to exist as well, then what does that mean for the rest of the universe?

If there is no life to experience it, does the universe even exist at all?