Dark Energy

What is dark energy and how it behaves

Our universe is composed of matter, dark matter, and dark energy. Matter forms about 5% of the universe while dark matter accounted for 28% and dark energy is responsible for 67% of the universe.

How dark energy comes into picture

In 1929, Edwin Hubble discovered that the universe is expanding. Since then various scientists did experiments to find out how much expansion slowed down over time. As scientists believed that gravity which binds galaxies together by attractive force would slow the expansion over time.

But in 1990, two different teams observed that the rate of expansion of galaxies is accelerating instead of deaccelerating. Scientists discovered that it is happening due to repulsive force and called it a “dark energy.”

It is described as ‘Cosmological constant’ in Einstein’s ‘General Theory of Relativity.’ It represents non-zero energy in the empty state or vacuum state. The more empty state you have the more dark energy density you have. Einstein added this constant in his theory of relativity to structure the universe. Later he removed it from the equation when Edwin Hubble discovered that the universe is expanding.

What is Dark Energy

It is a form of energy that exerts a repulsive pressure and acts as an opposite to gravity. It is supposed to be created from a not yet discovered exotic matter which has a negative mass. Albert Einstein defined it as a property of space. As space stretches, dark energy created. More space means, more dark energy, and more energy means more acceleration of the expansion of the universe.

How dark energy created

One theory is that it is created by an exotic matter with negative mass in a quantum vacuum. Scientists believe that in the empty state virtual particles appear and disappear continuously. These particles repel each other so it expands the space. The more particles get created, the more space gets stretched. This never-ending positive loop is responsible for the creation of energy.

But the problem with this theory is that the number of virtual particles (leptons, quark, fermions) present in the universe, will create so much space that atoms will separate from too much distance and it wouldn’t be possible for them to form the stars and galaxies. So scientists disregard this theory.

Scientists across the world still working out to find the source of this mysterious energy.