What is dark matter and is it true that 90% of our universe is made up of it?

Question

I've heard that somewhere.

Just wondering if there is any truth to it. (And what, exactly, dark matter is.)

Answer 1

first of all dark matter is makes up 25% of the universe and 70% of the universe is dark energy. Dark matter is something that doesnt react with the electromagnetic field. We can see existence of dark matter just like we see the existence of a black hole which is by looking at its gravitational attraction. it is unclear of the particles inside dark matter or energy. finding this out and understanding it is a big thing for cosmologists.

Answer 2

In physics and cosmology, dark matter is matter that does not interact with the electromagnetic force, but whose presence can be inferred from gravitational effects on visible matter. According to present observations of structures larger than galaxies, as well as Big Bang cosmology, dark matter accounts for the vast majority of mass in the observable universe. The observed phenomena which imply the presence of dark matter include the rotational speeds of galaxies, orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies. Dark matter also plays a central role in structure formation and galaxy evolution, and has measurable effects on the anisotropy of the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the "dark matter component."

The dark matter component has vastly more mass than the "visible" component of the universe. At present, the density of ordinary baryons and radiation in the universe is estimated to be equivalent to about one hydrogen atom per cubic meter of space. Only about 4% of the total energy density in the universe (as inferred from gravitational effects) can be seen directly. About 22% is thought to be composed of dark matter. The remaining 74% is thought to consist of dark energy, an even stranger component, distributed diffusely in space. Some hard-to-detect baryonic matter makes a contribution to dark matter but constitutes only a small portion. Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics. It has been noted that the names "dark matter" and "dark energy" serve mainly as expressions of human ignorance, much as the marking of early maps with "terra incognita."

Answer 3

What does the word dark connote to you? The word dark connotes not visible, hence not seen, hence not known. Dark matter refers to observed phenomena that cannot be explained yet which is nevertheless given a name. That is what the very word dark means. Yes, it is true that far and away most of the universe is an unknown. Rather than calling it unknown, some people now use the word dark. Your statement above asks if it is true that 90% of the universe cannot be seen and so must be assumed to exist even though not observed. The answer is yes.

Answer 4

Estimated mass of Universe doesn't fit the Observed speed of expanding of the Universe.

So the dark matter is supposed to be the remaining mass (difference between what we observe and those required to fit the the equations).

Dark matter can be neutrinos, for example. These particles (almost) do not interact with other matter.

Answer 5

For one hundred years science believed that 97% of the mass of the universe consisted of dark matter, but they have never been able to detect it. Nobody can describe what it is, or where it is. This dark matter was supposed to have enough gravitational force to slow down the expansion of the universe, but present evidence shows that the universe continues to expand. A proposal that dark energy must exist, causing the expansion, does not seem to be credible to me. In my opinion, neither of these nebulous entities exist, the reason for the expansion can be due to the inertia stored in the matter by the rapid expansion of the singularity of the big bang. I believe the universe is a closed system an it expand itself out of existence.