plerza said:Awesome, thanks! I usually stray away from wiki, but if you say those pages are accurate then I'm all in.
Yes, do start with these. The forums here work best if you have specific questions. Please come back with any of those at any time.mathman said:http://en.wikipedia.org/wiki/Dark_matter
http://en.wikipedia.org/wiki/Dark_energy
These concepts cannot be explained in a few short sentences. The above should help.
a negative pressure dark energy is the same thing as a cosmological constant. The difference is that the curvature from the cosmological constant is intrinsic, it's just there. With a dark energy case, the negative pressure creates the curvature.
Dark energy (or the cosmological constant) is fundamentally different from the normal metric expansion. You can consider it to be a force exerted everywhere (Because it's a constant). Because of this, it has a slight effect within galaxies. That's why, as George Jones showed, it's factored in for gravitational interactions, although it is far too weak to have a meaningful effect.
...the cosmological constant reduces the attractive force of gravity by some small amount. For atoms, this would have the effect of making atoms ever so slightly larger than they otherwise would be (the difference really is utterly negligible, however).
Dark matter and dark energy are two of the biggest mysteries in modern astrophysics. Dark matter is a type of matter that does not interact with light or any other form of electromagnetic radiation, making it invisible to telescopes. Dark energy, on the other hand, is a hypothetical form of energy that is believed to be responsible for the accelerating expansion of the universe.
Scientists have not directly observed dark matter or dark energy, but their existence is inferred through their effects on the visible matter and the expansion of the universe. For example, the rotation curves of galaxies and the gravitational lensing of light from distant galaxies suggest the presence of dark matter. The accelerating expansion of the universe, on the other hand, can be explained by the existence of dark energy.
Dark matter and dark energy are fundamentally different. Dark matter is a type of matter that has mass and interacts with gravity, while dark energy is a form of energy that has negative pressure and is responsible for the expansion of the universe. They have different effects on the universe and are believed to make up about 85% and 68% of the total matter and energy in the universe, respectively.
There are several theories about the nature of dark matter and dark energy, but they are still largely unknown. Some theories propose that dark matter is made up of new, yet to be discovered particles, while others suggest that it could be modifications to the laws of gravity. For dark energy, the most commonly accepted theory is the cosmological constant, which suggests that dark energy is a constant energy density throughout space.
The study of dark matter and dark energy is crucial in understanding the evolution and structure of the universe. By studying their effects on the visible matter and the expansion of the universe, scientists can gain insight into the formation of galaxies and the overall composition of the universe. Furthermore, a better understanding of these mysterious phenomena could potentially lead to advancements in technology and our understanding of fundamental physics.