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In astrophysics and cosmology, dark fluid is a theory proposed by Drs. HongSheng Zhao and Baojiu Li, which would supersede and combine the theories of Dark Matter and Dark Energy. Dr. Zhao is at the University of St. Andrews in Scotland; Dr. Li is at Cambridge in England.
To recap, Dark Matter is the much widely-accepted theory that the galaxies of the universe are filled up with a mysterious exotic invisible form of matter that doesn't interact with common everyday matter except by gravitational attraction. The gravity from this dark matter is said to be what holds the stars in the galaxies together, more so than the gravity of the stars themselves. This makes the gravity within each galaxy extra strong, and strong enough to retain all of their stars without having the stars at the outer edges drift away from their galaxy.
Dark Energy, on the other hand, is the even more mysterious discovery that the universe is expanding at an ever-more accelerating rate. In order for anything to accelerate, you need to add energy, and so since no one knows what the source of the energy is causing the universe to accelerate, they call it Dark Energy. It was understood that the universe was expanding, but until Dark Energy was discovered scientists believed the universe was decelerating due to gravity and would eventually stop and then begin to contract. Dark Energy thus acts like an anti-gravity force. Dark Energy is even stronger as a repulsive force than the added gravity that Dark Matter brings to galaxies, by a factor of 3:1.
Dark Fluid basically gets rid of Dark Matter, and states instead that the same effect that cause Dark Energy in the universe. The same energy that makes the universe expand faster, will also work in the opposite way inside galaxies by making the effect of gravity stronger. The Dark Fluid name comes from the fact that this energy flows around the universe like a fluid. This fluid is more specifically like an atmospheric weather system, such as on Earth. An atmosphere will usually try to expand out as much as possible, except in certain places where there is dust particles it will condense to form clouds and rain, etc. In this case the dust is actually what we'd call the galaxies. The Dark Fluid condenses around the galaxies thus making them seem even bulkier, but everywhere else it just keeps expanding. The Dark Fluid model also comes up with a ratio of 3:1 for expansion vs. contraction, which is the ratio observed between Dark Energy vs. Dark Matter.
[edit] External Links
- [1]Dark Fluid: Towards a unification of empirical theories of galaxy rotation, Inflation and Dark Energy
