What do you understand by dark matter and dark energy and How important is their contribution in the formation of the universe?

You must have seen and heard a lot about dark matter or dark energy

Many Hollywood movies have also been produced on this mysterious word. But at present, it remains the basis of important scientific research.

However, this term is not at all new. It was first detected in the 1920s

The origin of the term dark energy is believed to be from Einstein's theory of 'General Relativity'.

It has been proved from astronomical studies that about 25% of the universe is dark matter while 70% is dark energy. 

Therefore, both dark matter and dark energy are considered to be big players of the universe. 

According to one estimate, what we can see or touch is only 5 percent of the universe. 

The remaining 95 percent of the universe is made up from dark matter and dark energy. Hence their importance increases from this point of view.

After all, what is dark matter and dark energy that is so important astronomically?

Dark Matter

According to astronomers, 'this is the invisible force providing energy to the galaxies located in our universe'. 

But astronomical studies are still far from better understanding about dark matter.

Researchers say that it is not affected by any kind of radiation, but the force of gravity affects the dark matter immediately.

Horst Fischer, researcher at the CAST (CERN Axion Solar Telescope) experiment at CERN, says that 'dark matter is quite mysterious and until its discovery we have no clue what it might be'.

We know that galaxies rotate, and physics tells us that stars farther away from the center of the galaxy move slower.

But the galaxies that astronomers study do not obey this law of physics. Because the outer stars move as fast as they get closer. 

At the same rate as they spin, the external mass flows out into space. The main reason for this is the instability of the orbit.

Thus, other arguments and beliefs about dark matter also prevail. 

Light is bent due to the strong gravitational force. By what distance is light displaced by galaxies?  

No exact guess has been made about this so far. But astronomers believe it may be much more than what we anticipate through telescopes.

Even galaxy clusters require a dark matter web around them to explain their formation. 

Most astronomers around the world accept the existence of dark matter, but what is it made of? No one has the answer yet.

In this regard, Professor Fischer conjectures that 'In about 3 cubic centimeters you will have the mass of dark matter equal to the mass of a proton'.

So it is very dense and amazing in nature.  Till now the existence of dark matter is considered only in theories. Exploring it in practical terms remains a far cry.

Candidates for this mysterious substance are supersymmetric particles, such as weekly interacting massive particles or other hypothetical particles such as xenons or sterile neutrinos.

None of these have been discovered yet. But theoretically they have properties that closely match those of dark matter.

A recent study theorizes that 'dark matter 'changes shape' between phases at a variety of size scales, from particles to superfluids, and this is the main reason why it is so difficult to detect.

Despite strong evidence in favor of dark matter, several alternative theories also exist that often require the introduction of drastic modifications to general relativity to explain the observations.

Dark Energy

The mysterious matter that creates tension in space is called dark energy. 

Dark matter may sound a bit scary, but there is nothing like dark energy. 

It is through dark energy that the expansion of the universe continues to accelerate. 

Due to this the universe is continuously expanding rapidly.

Gravity is an attractive force, and with mass dotted throughout space, many scientists initially assumed that the universe would eventually stop expanding under the gravitational pull exerted by massive objects.

However, in the late 1990s, a supernova observation showed the opposite – it showed that the universe was expanding at a much faster rate than previously thought.  

This suggests that a strange effect is in action. Which can be called dark energy.

There is a great deal of diversity in the theories of dark energy. 

But in this context Einstein's cosmological constant theory is universal.

It was included in the theory of general relativity to balance gravity and maintain a stable universe (one that is neither expanding nor shrinking). 

But Einstein abandoned it when the American astronomer Edwin  Hubble found that the universe is expanding.

As a candidate for dark energy, the cosmological constant is a constant energy field that fills space evenly, but does not match the observational model.

Quantum field theory predicts a vacuum energy that may be equal to the cosmological constant.

Some researchers believe that dark energy changes over time and is not a constant effect. 

This dark energy field is sometimes referred to as a 'quintense' and may be a lighter relative of the Higgs boson.

This theory, depending on how the 'quintessence' develops, can predict how the universe will end. 

Hypotheses trying to exclude dark energy often rely on modified theories of gravity.

Some theories also hold that the acceleration of expansion is an illusion due to relative motion in our local galaxy cluster or the low density of space.

"Normally, we use the term dark energy a lot, but we don't even really know whether dark energy is accelerating the universe," says Professor Freeman.

It may be that we don't understand gravity. That something happens to the gravity of the universe's mass that changes its behavior, and this may be what gives rise to cosmic acceleration.

Are we wandering to understand dark matter and dark energy?

There is still a lot of work to do to fully understand dark matter and dark energy. 

However, these two are discussed as separate substances. 

Researchers are trying to understand the possible relationship between these two.

It can also happen that dark matter turns into dark energy or both have the same method of origin. 

They may also be manifestations of brighter-than-light particles called tachyons. 

Dark matter can tell us how the universe began and its fate can be decided by dark energy.