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Understanding Galactic Rotation through Fluid Dynamics.

The study of fluid dynamics, commonly associated with liquids and gases on Earth, can provide insights into cosmic phenomena.

Fluid dynamics plays a crucial role in cosmology, the study of the origin, evolution, and structure of the universe. It helps us understand the large-scale motions of matter and energy in the cosmos, providing insights into the formation of galaxies, stars, and the cosmic microwave background radiation.

Whirlpool as an analogy for Galaxy Rotation

Consider the analogy of a whirlpool, a swirling vortex of water; its influence extends far beyond its immediate vicinity, affecting the surrounding water currents and even objects at a distance. This analogy not only sheds light on the mechanism behind galactic rotation but also prompts questions about the interconnectedness of the cosmos.

The rotation of galaxies is not uniform, however. The stars and gas in the outer regions of a galaxy rotate more slowly than those in the inner regions. This is because the gravitational pull of the black hole is strongest at the centre of the galaxy.

A gif of a whirlpool as an analogy for galaxy rotation

The analogy of a whirlpool can again be helpful in understanding this. The water at the edge of a whirlpool rotates more slowly than the water at the centre. This is because the water at the edge is further away from the centre of rotation, and therefore experiences a weaker "gravitational pull".

Conceptualizing spacetime, the fabric of the universe, as a fluid, opens up an entirely different perspective on celestial interactions.

Just as water can flow around obstacles and create turbulent eddies, spacetime can bend and twist around massive objects like stars and galaxies. This bending and twisting of spacetime is gravity.

Due to the curvature of spacetime, gravity is a consequence.

Of course, this is nothing new, but using fluid dynamics analogies to explain spacetime can help us visualize it.

Spacetime: A Physical thing, Not an Abstract Concept

Spacetime is often treated as some abstract concept, a mathematical construct that describes the relationship between space and time. However, this perspective may limit our understanding of gravity and the cosmos.

A more productive approach is to view spacetime as a physical entity, like a fluid or a trampoline.

spacetime in 3D

Just as a bowling ball placed on a trampoline creates a curvature in the surface, massive objects like stars and planets warp spacetime. This curvature is what we experience as gravity. The more massive an object is, the greater the curvature it produces.

Imagine the Sun as the bowling ball and spacetime as the trampoline. The Sun's immense mass causes a deep indentation in spacetime, much like the bowling ball sinks into the trampoline. This indentation guides the motion of other objects, including planets, like marbles rolling around the curved surface of the trampoline.

Viewing spacetime as a physical substance rather than an abstract concept provides a more tangible understanding of gravity. It allows us to visualize how mass directly affects the fabric of the universe, shaping the paths of objects and influencing the structure of spacetime itself., helping us see how gravity is a consquence.

Spacetime may be a superfluid.

Recent pondering has suggested that spacetime itself is a superfluid, so the whirlpool analogy of a galaxy also prompts thought-provoking questions about the interconnectedness of the cosmos. If spacetime is indeed a superfluid, then every celestial body, from the smallest asteroid to the largest quasar, is immersed in this cosmic medium.

Every movement, every interaction, every gravitational pull could send ripples through the fabric of spacetime, affecting distant objects in ways we are only beginning to understand.

The idea that spacetime might be a superfluid is fascinating and potentially groundbreaking. If true, it would have profound implications for our understanding of the universe and its workings.

A superfluid is a state of matter in which a fluid exhibits no viscosity and zero resistance to flow. This means that any motion within a superfluid is perfectly smooth and frictionless. Superfluids also can flow through extremely narrow channels without loss of energy.

If spacetime were a superfluid, it would mean that gravity, the force that governs the interactions between massive objects, could propagate through spacetime without any loss of energy. This would have a number of implications for our understanding of the universe.

For example, it would mean that gravitational waves, ripples in spacetime caused by the movement of massive objects, could travel through the universe without any loss of energy. This would allow us to detect gravitational waves from even the most distant objects in the cosmos, providing us with a new window into the universe's past.

Another analogy between gravitational waves and the ripples formed by a rock thrown into a pond can be drawn, which is helpful in understanding certain aspects of how gravitational waves propagate through space. When a rock is thrown into a pond, it creates ripples that spread outwards in all directions. Similarly, when massive objects accelerate or move in space, they can create ripples in the fabric of spacetime, which we perceive as gravitational waves.

It is still speculative whether spacetime might be a superfluid, but the topic is being actively researched. In recent years, there has been an increasing amount of evidence to support the idea that spacetime behaves like a superfluid. For example, observations of rapidly rotating stars have shown that they can drag spacetime around them in a way that is consistent with the properties of a superfluid.


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