Part 2/9:
Dark matter is hypothesized to make up about 27% of the universe, yet no direct evidence of it exists. It was introduced to explain discrepancies in the rotational speeds of galaxies, where the visible mass does not account for the gravitational effects observed. Similarly, dark energy, which comprises around 68% of the universe, was proposed to explain the observed acceleration in the expansion of the universe. This makes up the majority of the universe's composition, yet both remain mysterious.