Scientists are trying to figure out the existence of dark matter.
It's a mysterious particle that has many uses, but is currently inconspicuous. It can be divided into cold, warm, and hot categories based on its velocity. The difference in these categories comes from the different types of particles that have been proposed as dark matter. For example, the hot dark matter particle has been thought of as a neutrino, but its existence has yet to be verified.
It is non-baryonic
The observable universe is composed of both baryonic and non-baryonic matter. The former is often divided into Hot Dark Matter (HDM) and Cold Dark Matter (CDM). In the Special Theory of Relativity, nearly massless particles move at c. As they would have relativistic velocities, they would tend to smooth fluctuations in matter density. Despite this, some scientists believe dark matter is the missing link in the puzzle of our universe.
It is made up of subatomic particles
The dark matter of our universe is a mysterious substance with no apparent mass. Various theories suggest that it is made up of subatomic particles. Axions are one of the most promising candidates. These particles should have a mass of 50 to 1500 micro-electronvolts, and be ten billion times lighter than electrons. The density of axions in the universe should be approximately a trillion times that of the Milky Way. The presence of dark matter is not confirmed by current experiments, but the researchers are convinced that there is dark matter.
It interacts with ordinary baryonic matter
We know that dark matter exists, but what exactly is its density? The most widely accepted estimate is about four percent of the critical mass of the universe, or CMB, which was reached during the big bang, about 13.8 billion years ago. Other estimates have been much more conservative, with dark matter ranging anywhere from 0.0015% of CMB to 0.0001% of CMB. The CMB measurement yields an independent baryon density, which is consistent with nucleosynthesis.
It is expanding faster than the distant Universe
A new study has found that the distant Universe is expanding at a faster rate than light. Observations from the Planck mission, which was active from 2009 to 2013, suggest that the expansion rate of the universe is much faster than previously thought. This new finding confirms the previous research that gravity does not reign over the expansion of the universe. This means that the Universe will double in size within the next 10 billion years.
Dark matter interacts gravitationally with ordinary matter, releasing energy and heat into exoplanets. Scientists are studying whether these planets might have captured dark matter. If they have, dark matter would likely cluster around the cores of these exoplanets. Researchers also think that super-Jupiters may have dark matter because of their large mass and well-known temperatures. But it's not clear how much of this mysterious material is actually present in these exoplanets.
It has complex time behaviour
The search for dark matter is a highly complex one. It requires the extension of the basic knowledge of particle physics and cosmology. If dark matter is real, it may suggest some sort of cosmological modification in gravity. Its discovery is led by experiments for direct detection and indirect detection. Scientists have mapped out a few ways to detect it. Below are some of them. Each of them will reveal some aspect of dark matter's time behaviour.