user: I'm interested in learning about quantum entanglement. I recently learned that the presence of dark matter in the galaxy is expanding at consistent rates equally across our universe, but not all in the same places. Outer galaxies and the galaxy itself is actually too small to be affected, but dark matter is vastly present in the space between galaxies.

assistant: Quantum entanglement and dark matter are two distinct topics in physics. Let me briefly explain both to give you a better understanding of each.

## Quantum Entanglement

Quantum entanglement is a phenomenon in quantum mechanics where two or more particles become correlated in such a way that the state of one particle is dependent on the state of the other, regardless of the distance between them. As Einstein called it, this "spooky action at a distance" has been experimentally confirmed and is a fundamental aspect of quantum mechanics.

Entangled particles can be created in various ways, such as decaying a single particle into two or using specific interactions between particles. Once particles are entangled, the properties of one particle cannot be described independently of the other. When a measurement is made on one of the entangled particles, it instantly determines the properties of the other particle, even if vast distances separate them.

## Dark Matter

Dark matter is a mysterious form of matter that does not interact with electromagnetic radiation, which makes it invisible to our detection methods. It is estimated to account for about 85% of the total matter in the universe. The presence of dark matter was first inferred from its gravitational effects on visible matter, such as the motion of galaxies and the universe's large-scale structure.

Dark matter is thought to be responsible for the observed consistent rates of expansion of the universe and the formation of cosmic structures. Although the distribution of dark matter is not uniform, it is more concentrated around galaxy clusters and filaments, while the space between galaxies has less dark matter. Dark matter's influence on the cosmic structure is due to its gravitational attraction, which helps to keep galaxies and galaxy clusters together.

## Conclusion

To summarize, quantum entanglement is a phenomenon in quantum mechanics that deals with particle correlations. At the same time, dark matter is a form of invisible matter that affects the large-scale structure and expansion of the universe. These two topics are not directly related, but both are essential areas of study in modern physics.

user: What about dark energy? Are dark matter and dark energy related?

assistant: Yes, dark matter and dark energy are related concepts in cosmology, but they are distinct from each other. While dark matter is believed to be a form of matter that does not interact electromagnetically and is inferred from its gravitational effects on visible matter, dark energy is a hypothetical form of energy that is thought to be responsible for the accelerated expansion of the universe.

Dark energy was first proposed as a theoretical concept to explain the observations that the universe is expanding at an accelerating rate, based on studies of distant supernovae in the late 1990s. It is postulated to be a form of energy that permeates the universe and has negative pressure, driving the accelerated expansion of the universe by exerting a repulsive force that counteracts the gravitational attraction of matter.

Dark matter, on the other hand, is believed to make up a significant portion of the total mass in the universe, based on its gravitational effects on visible matter, such as the motion of galaxies and the large-scale structure of the universe. It is thought to be composed of a type of matter that does not interact electromagnetically and does not emit, absorb, or reflect any electromagnetic radiation, making it invisible and difficult to detect directly.

Dark matter and dark energy are often considered as two distinct components of the universe, with dark matter providing the gravitational scaffolding that helps galaxies and other cosmic structures form, while dark energy drives the accelerated expansion of the universe. They are believed to account for a large majority of the total mass-energy content of the universe, with ordinary matter, which makes up the visible stars, planets, and galaxies, comprising only a small fraction of the total.

While dark matter and dark energy are related in the sense that they are both hypothetical forms of matter and energy that are believed to exist to explain certain cosmological observations, they are distinct concepts with different properties and behaviors, and our understanding of them is still an active area of research and investigation in modern cosmology.