prompter: what is dark matter

assistant: Dark matter is an hypothetical form of matter, which does not interact with the electromagnetic field. It is thought to account for approximately 85% of the matter in the known universe, if it does exist.

assistant: Dark matter is an invisible form of matter that is believed to make up around 27% of the universe. It is most likely composed of particles that do not interact with light, making it impossible to observe directly. Scientists believe that this dark matter is responsible for the gravitational force that keeps galaxies together and explains why the universe is expanding at an accelerating rate. Some theories suggest that dark matter particles interact with each other through gravity, but more research is needed to confirm this hypothesis.

So far, dark matter has only been observed through its gravitational effects. The most widely accepted explanation for dark matter is that it consists of Weakly Interactive Massive Particles (WIMPs). WIMPs interact with gravity and with themselves, but not with normal matter. These particles could explain why galaxies are rotating faster than what is expected under the theory of general relativity. Other theories suggest that dark matter could be made up of axions, sterile neutrinos, or other particles. While the true nature of dark matter remains a mystery, its effects can be studied through mathematical models and computer simulations.

prompter: Are there any suggested or theoretical tests we could preform to determine what dark matter is?

assistant: For the first 150 million years after the Big Bang, there were no galaxies or stars or planets. The universe was featureless.

As time passed, the first stars formed. Stars collected into galaxies. Galaxies began to cluster together. Those clusters are made up of the galaxies and all the material between the galaxies. Clumps of matter in smashed into each other, and the planets in our solar system began to form around the sun.

Something must hold our solar system, galaxies and clusters of galaxies together. And gravity is that "glue."

In some clusters, the space between galaxies is filled with gas so hot, scientists cannot see it using visible light telescopes. The gas only can be seen as X-rays or gamma rays. Scientists look at that gas and measure how much there is between galaxies in clusters. By doing this, they discovered that there must be five times more material in the clusters than we can detect. The invisible matter that we can't detect is called "dark matter."

prompter: What experiments are being done in the field of Dark Matter

assistant: Dark Matter is a specific kind of theoretical matter that is extremely dark, and is comprised of some kind of strange 'matter-like' properties, in that it occupies space and it seems to exist. 
However, it isn't really matter and it isn't actually dark either. Scientists just call it that because they haven't quite figured out what it's made of yet. But apparently it exists because they've detected a massive portion of the universe that contains something unexplainable, and the truth is that this stuff is what most of the entire universe is made of and we have absolutely no idea what it is.

In summary, dark matter is something that we can't really define clearly yet due to lack of current scientific understanding, but it appears that it's basically almost everywhere.

prompter: Uhh... if dark matter isn't actually dark, why did you call it "a specific kind of theoretical matter that is extremely dark," then?

prompter: Are there any alternative explanations other than dark matter?

prompter: In other words, there is no evidence for the existence of dark matter other than that of as a "fill-in" for gravitational models.  It is therefore a purely theoretical construct with no basis in reality, not so?

prompter: Has there been some recent breakthrough on this topic ? And what about dark energy too ?

prompter: Could you be a bit more scientific? What are the generally accepted theories regarding Dark Matter? And what is the evidence against it? But please do keep it simple for a layman.