Dark energy is a theoretical concept in physics used to explain the observed accelerated expansion of the universe. It is not directly related to empty space but is thought to be an intrinsic property of space itself.
According to the prevailing cosmological model, known as the Lambda-CDM model, dark energy is considered a form of energy that fills the entire universe uniformly. It is postulated to have negative pressure, which generates a repulsive gravitational effect, leading to the accelerated expansion of the universe.
The term "empty space" typically refers to the absence of matter and energy, where no particles or fields are present. However, even in the absence of matter and radiation, space can still possess properties and characteristics. In the context of dark energy, empty space is not completely devoid of energy. It is postulated that there exists a non-zero energy density associated with empty space, often referred to as the vacuum energy or cosmological constant.
The nature of dark energy and its connection to the properties of space are still subjects of active research and investigation in cosmology and theoretical physics. Its existence and effects have been inferred through observational data, such as measurements of the cosmic microwave background radiation and the large-scale structure of the universe. However, the fundamental origin and precise nature of dark energy remain open questions in physics.