Dark Phenomena

• Black Hole

• An object in space that has almost no volume and infinite density. Its gravity is so strong that within a certain distance from it, nothing, not even light, can escape. A black hole is formed when a star more than 10 times as massive as our Sun collapses and explodes as a supernova. A super massive black hole with the mass of a million or more stars is thought to reside at the centre of most galaxies. Speculated by inference only.

This is all conjecture and unproven, though accepted by the scientific community as 'fact'.

• Dark Energy

• A hypothetical and speculative form of energy that permeates all space and is thought to increase the rate of expansion of the universe. The Cosmological Constant And Dark Energy. Dark Energy is the leading explanation accounting for the recent observation that the universe appears to be expanding at an accelerating rate. This is a consequence of observation of Type 1a Supernovae. Dark Energy currently accounts for 74% of the total mass-energy of the ('known') universe.

• Dark Matter

• Matter that cannot be observed because it does not emit electromagnetic radiation. Its existence is inferred (fits the paradigm) by its gravitational influence in galaxy clusters and galactic halos as well as the warping of space measured by gravitational lensing.
  

The three concepts of the Black Hole, Dark Energy and Dark Matter constitute speculation to attempt the explanation of observed phenomena. Mostly gravitational affects. Nothing can be seen, all blackness or invisible, and so none of it can be examined. Only the inferences. This by itself should create wariness about the entire topic of speculation. The centre of any galaxy is proposed to contain a Black Hole, yet most images show a brilliant light source. Should such a massively high gravitational entity exist, the light escaping from this location is in conflict with the idea that even light cannot outrun its pull. The centre of a (spiral) galaxy should be empty blackness. No light.

The Local Group is the name given to the 36 or so galaxy groups that span an estimated 6 million light years across. This region is a (presumed) small part of the universe though how small or large cannot ever be determined. Perhaps containing over a trillion Suns that are assumed to be similar, though varying in magnitude and size to The Sun at the centre of our solar system [8 planets (excluding Pluto)], the Milky Way ('home' galaxy) is at the edge of a Local Supercluster. More speculation suggests that there might be a Dark Galaxy, a clump of hydrogen and Dark Matter that has yet to form stars. Highly speculative. Through collisions and mergers of small galaxies and star clusters, order has evolved from chaos and larger galaxies have been created from the aggregation of many smaller ones. This blending of galaxies has been described as being like a gigantic food mixer: the Cosmic Cuisinart. Contrails a hundred million light-years long exist made up of the wispy streams of stars generated from the ripped-apart galaxies and shine as the halo of The Milky Way (Spiral galaxy). This halo is possibly populated by older stars that formed in the Local Group billions of years ago.

Dwarf galaxies are fragile and show disruption as they venture close to the gravitational centre of The Milky Way. They currently represent the best model for the birth of a galaxy in the early universe and predict an invisible form of matter known only by its gravitational force. This is known as Dark Matter since it has no light. After the Big Bang, Dark Matter was able to attract ordinary matter in the form of vast clouds of gas. The most dense clouds contracted to form stars and galaxies and the dwarf galaxies were the first to emerge.