What the definition of dark energy?
Energy that humans cannot observe directly
Energy that has a small effect on the universe
Energy characterized by black and dark gray colors
Energy that is only emitted by glowing nebulae.
The first option, "Energy that humans cannot observe directly," is the closest definition of dark energy. Dark energy refers to a hypothetical form of energy that is believed to make up the majority of the energy content of the universe. It is currently not directly observable or detectable but is inferred through its gravitational effects on the expansion of the universe.
Dark energy is energy that humans cannot observe directly.
The definition of dark energy is energy that has a small effect on the universe and is not directly observable by humans. It is important to note that dark energy is not characterized by black and dark gray colors, nor is it emitted only by glowing nebulae.
To arrive at the accurate definition, we need to explain the process of discovering dark energy. Dark energy is a theoretical concept introduced to explain the observed accelerated expansion of the universe. In the late 1990s, astronomers studying distant supernovae (exploding stars) made a surprising discovery that the expansion of the universe was accelerating rather than slowing down as expected. This suggested the existence of a mysterious force that counteracted gravity and pushed galaxies apart.
Further studies and observations of cosmic microwave background radiation, galaxy clustering, and large-scale structure all provided evidence supporting the presence of dark energy. However, unlike everyday energy or matter, dark energy does not interact with electromagnetic radiation or other forces apart from gravity. This lack of interaction makes it challenging to directly observe or measure dark energy.
Therefore, dark energy is defined as a form of energy that is believed to pervade all space and exerts a repulsive force, causing the universe's expansion to accelerate. It constitutes about 68% of the total energy content of the universe. Although it is not directly observable, its existence is inferred through its effects on the expansion of the universe and the large-scale distribution of galaxies.