What is dark matter?

• Dark Matter refers to the hypothetical matter that scientists have not been able to locate in the universe – either through telescopes or using any other technological method. 
• Dark matter works like an attractive force — a kind of cosmic cement that holds our universe together. 
• Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot. 
• In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter. 
• In the 1930s, astronomer Fritz Zwicky speculated about the presence of “dark matter” for the first time.

What is Dark energy?

• Dark energy is a repulsive force — a sort of anti-gravity — hypothesised to be responsible for the accelerated expansion of the Universe. 
• Like Dark Matter, Dark Energy is not directly observed, but rather inferred from observations of gravitational interactions between astronomical objects.
• It is distributed evenly throughout the universe, not only in space but also in time – in other words, its effect is not diluted as the universe expands. 
• The even distribution means that dark energy does not have any local gravitational effects, but rather a global effect on the universe as a whole. This leads to a repulsive force, which tends to accelerate the expansion of the universe. 
• Dark energy is the far more dominant force of the two, accounting for roughly 68 percent of the universe’s total mass and energy. Dark matter makes up 27 percent. And the rest — a measly 5 percent — is all the regular matter we see and interact with every day. 
• Current hypotheses propose dark energy might emerge from the bubbling of empty space, a small effect that is also widespread, making it powerful enough to drag apart clusters of galaxies without ripping them apart from within.