Understanding the True Bottom of Space: The Concept of the Celestial Hemisphere

In the vast expanse of the universe, the concept of 'bottom' as we understand it on Earth becomes obsolete. Space, as we know it, doesn't have a definitive bottom or top. This is a fundamental aspect of our understanding of the cosmos, particularly through the lens of general relativity and quantum mechanics. However, in navigating the celestial sphere, we can still find useful frameworks to understand the vastness around us.

The Celestial Hemisphere: Northern and Southern Skies

When we talk about the 'bottom' in space, we often refer to the southern hemisphere of the celestial sphere, which is typically dominated by constellations like Hydra and Aquarius. In the context of Earth, the southern sky above Antarctica is considered as the area below the observer. Similarly, the northern sky, centered around the North Star Polaris, represents what we conventionally consider 'above.' However, it's important to note that these terms are relative and change throughout the year, as the Earth's axis of rotation shifts.

Before Polaris became our current northern star, we had other guiding stars like Beta Ursa Minor and Gamma Ursa Minor. This shift in the pole star over thousands of years demonstrates the dynamic nature of the Earth's rotation and its impact on our celestial navigation.

No Bottom or Top in Space: The 5D Tesseract

The concept of 'down' in space is further complicated by the depiction in Interstellar, particularly the scene involving a tesseract or a 5-dimensional object. In the movie, the tesseract represents a 5th-dimensional space that exceeds our 3D understanding. While the tesseract is a work of pure fiction, it helps to visualize the complex nature of space and time in higher dimensions.

One central idea to grasp is that in space-time, there is no true bottom or top. The space-time fabric is continuous and unbroken, forming a 4-dimensional grid-like structure, with the added complexity of time as another dimension. This understanding aligns more closely with the principles of general relativity and quantum mechanics.

General Relativity and Quantum Foam

General relativity, a cornerstone of our understanding of gravity, tells us that the fabric of space-time can bend and twist. This bending and twisting create the phenomena we observe as gravity. However, at the smallest scales, beyond the confines of our everyday experience, the space-time fabric becomes even more complex. The theoretical concept of quantum foam suggests that space-time at the Planck scale is filled with microscopic bubbles of space-time that continually form and vanish.

Imagining the space-time fabric as a grid-like structure with time as the fourth dimension can help us visualize the embedding of objects within this framework. Just as objects are meshed within a 3D Cartesian coordinate system, we can think of space-time as a more complex, wavy, and dynamic structure that influences and is influenced by the objects within it.

Conclusion: Embracing the Infinite

The true bottom of space, as we understand it in the context of our current scientific knowledge, does not exist. Instead, we have the celestial hemisphere, the northern and southern skies, and the complex fabric of space-time that is both beautiful and infinitely intriguing. The concepts of general relativity and quantum mechanics continue to provide fascinating insights into the nature of the universe, reminding us of the endless possibilities and mysteries that lie within the cosmos.